Sample records for antarctic southern ocean

  1. Antarctic warming driven by internal Southern Ocean deep convection oscillations

    NASA Astrophysics Data System (ADS)

    Martin, Torge; Pedro, Joel B.; Steig, Eric J.; Jochum, Markus; Park, Wonsun; Rasmussen, Sune O.

    2016-04-01

    Simulations with the free-running, complex coupled Kiel Climate Model (KCM) show that heat release associated with recurring Southern Ocean deep convection can drive centennial-scale Antarctic temperature variations of 0.5-2.0 °C. We propose a mechanism connecting the intrinsic ocean variability with Antarctic warming that involves the following three steps: Preconditioning: heat supplied by the lower branch of the Atlantic Meridional Overturning Circulation (AMOC) accumulates at depth in the Southern Ocean, trapped by the Weddell Gyre circulation; Convection onset: wind and/or sea-ice changes tip the preconditioned, thermally unstable system into the convective state; Antarctic warming: fast sea-ice-albedo feedbacks (on annual to decadal timescales) and slower Southern Ocean frontal and sea-surface temperature adjustments to the convective heat release (on multi-decadal to centennial timescales), drive an increase in atmospheric heat and moisture transport towards Antarctica resulting in warming over the continent. Further, we discuss the potential role of this mechanism to explain climate variability observed in Antarctic ice-core records.

  2. Antarctic icebergs melt over the Southern Ocean : Climatology and impact on sea ice

    NASA Astrophysics Data System (ADS)

    Merino, Nacho; Le Sommer, Julien; Durand, Gael; Jourdain, Nicolas C.; Madec, Gurvan; Mathiot, Pierre; Tournadre, Jean

    2016-08-01

    Recent increase in Antarctic freshwater release to the Southern Ocean is suggested to contribute to change in water masses and sea ice. However, climate models differ in their representation of the freshwater sources. Recent improvements in altimetry-based detection of small icebergs and in estimates of the mass loss of Antarctica may help better constrain the values of Antarctic freshwater releases. We propose a model-based seasonal climatology of iceberg melt over the Southern Ocean using state-of-the-art observed glaciological estimates of the Antarctic mass loss. An improved version of a Lagrangian iceberg model is coupled with a global, eddy-permitting ocean/sea ice model and compared to small icebergs observations. Iceberg melt increases sea ice cover, about 10% in annual mean sea ice volume, and decreases sea surface temperature over most of the Southern Ocean, but with distinctive regional patterns. Our results underline the importance of improving the representation of Antarctic freshwater sources. This can be achieved by forcing ocean/sea ice models with a climatological iceberg fresh-water flux.

  3. Reorganization of Southern Ocean plankton ecosystem at the onset of Antarctic glaciation.

    PubMed

    Houben, Alexander J P; Bijl, Peter K; Pross, Jörg; Bohaty, Steven M; Passchier, Sandra; Stickley, Catherine E; Röhl, Ursula; Sugisaki, Saiko; Tauxe, Lisa; van de Flierdt, Tina; Olney, Matthew; Sangiorgi, Francesca; Sluijs, Appy; Escutia, Carlota; Brinkhuis, Henk; Dotti, Carlota Escutia; Klaus, Adam; Fehr, Annick; Williams, Trevor; Bendle, James A P; Carr, Stephanie A; Dunbar, Robert B; Flores, José-Abel; Gonzàlez, Jhon J; Hayden, Travis G; Iwai, Masao; Jimenez-Espejo, Francisco J; Katsuki, Kota; Kong, Gee Soo; McKay, Robert M; Nakai, Mutsumi; Pekar, Stephen F; Riesselman, Christina; Sakai, Toyosaburo; Salzmann, Ulrich; Shrivastava, Prakash K; Tuo, Shouting; Welsh, Kevin; Yamane, Masako

    2013-04-19

    The circum-Antarctic Southern Ocean is an important region for global marine food webs and carbon cycling because of sea-ice formation and its unique plankton ecosystem. However, the mechanisms underlying the installation of this distinct ecosystem and the geological timing of its development remain unknown. Here, we show, on the basis of fossil marine dinoflagellate cyst records, that a major restructuring of the Southern Ocean plankton ecosystem occurred abruptly and concomitant with the first major Antarctic glaciation in the earliest Oligocene (~33.6 million years ago). This turnover marks a regime shift in zooplankton-phytoplankton interactions and community structure, which indicates the appearance of eutrophic and seasonally productive environments on the Antarctic margin. We conclude that earliest Oligocene cooling, ice-sheet expansion, and subsequent sea-ice formation were important drivers of biotic evolution in the Southern Ocean.

  4. Antarctic and Southern Ocean influences on Late Pliocene global cooling

    USGS Publications Warehouse

    McKay, Robert; Naish, Tim; Carter, Lionel; Riesselman, Christina; Dunbar, Robert; Sjunneskog, Charlotte; Winter, Diane; Sangiorgi, Francesca; Warren, Courtney; Pagani, Mark; Schouten, Stefan; Willmott, Veronica; Levy, Richard; DeConto, Robert; Powell, Ross D.

    2012-01-01

    The influence of Antarctica and the Southern Ocean on Late Pliocene global climate reconstructions has remained ambiguous due to a lack of well-dated Antarctic-proximal, paleoenvironmental records. Here we present ice sheet, sea-surface temperature, and sea ice reconstructions from the ANDRILL AND-1B sediment core recovered from beneath the Ross Ice Shelf. We provide evidence for a major expansion of an ice sheet in the Ross Sea that began at ~3.3 Ma, followed by a coastal sea surface temperature cooling of ~2.5 °C, a stepwise expansion of sea ice, and polynya-style deep mixing in the Ross Sea between 3.3 and 2.5 Ma. The intensification of Antarctic cooling resulted in strengthened westerly winds and invigorated ocean circulation. The associated northward migration of Southern Ocean fronts has been linked with reduced Atlantic Meridional Overturning Circulation by restricting surface water connectivity between the ocean basins, with implications for heat transport to the high latitudes of the North Atlantic. While our results do not exclude low-latitude mechanisms as drivers for Pliocene cooling, they indicate an additional role played by southern high-latitude cooling during development of the bipolar world.

  5. The Effects of Interactive Stratospheric Chemistry on Antarctic and Southern Ocean Climate Change in an AOGCM

    NASA Technical Reports Server (NTRS)

    Li, Feng; Newman, Paul; Pawson, Steven; Waugh, Darryn

    2014-01-01

    Stratospheric ozone depletion has played a dominant role in driving Antarctic climate change in the last decades. In order to capture the stratospheric ozone forcing, many coupled atmosphere-ocean general circulation models (AOGCMs) prescribe the Antarctic ozone hole using monthly and zonally averaged ozone field. However, the prescribed ozone hole has a high ozone bias and lacks zonal asymmetry. The impacts of these biases on model simulations, particularly on Southern Ocean and the Antarctic sea ice, are not well understood. The purpose of this study is to determine the effects of using interactive stratospheric chemistry instead of prescribed ozone on Antarctic and Southern Ocean climate change in an AOGCM. We compare two sets of ensemble simulations for the 1960-2010 period using different versions of the Goddard Earth Observing System 5 - AOGCM: one with interactive stratospheric chemistry, and the other with prescribed monthly and zonally averaged ozone and 6 other stratospheric radiative species calculated from the interactive chemistry simulations. Consistent with previous studies using prescribed sea surface temperatures and sea ice concentrations, the interactive chemistry runs simulate a deeper Antarctic ozone hole and consistently larger changes in surface pressure and winds than the prescribed ozone runs. The use of a coupled atmosphere-ocean model in this study enables us to determine the impact of these surface changes on Southern Ocean circulation and Antarctic sea ice. The larger surface wind trends in the interactive chemistry case lead to larger Southern Ocean circulation trends with stronger changes in northerly and westerly surface flow near the Antarctica continent and stronger upwelling near 60S. Using interactive chemistry also simulates a larger decrease of sea ice concentrations. Our results highlight the importance of using interactive chemistry in order to correctly capture the influences of stratospheric ozone depletion on climate

  6. Antarctic and Southern Ocean influences on Late Pliocene global cooling

    PubMed Central

    McKay, Robert; Naish, Tim; Carter, Lionel; Riesselman, Christina; Dunbar, Robert; Sjunneskog, Charlotte; Winter, Diane; Sangiorgi, Francesca; Warren, Courtney; Pagani, Mark; Schouten, Stefan; Willmott, Veronica; Levy, Richard; DeConto, Robert; Powell, Ross D.

    2012-01-01

    The influence of Antarctica and the Southern Ocean on Late Pliocene global climate reconstructions has remained ambiguous due to a lack of well-dated Antarctic-proximal, paleoenvironmental records. Here we present ice sheet, sea-surface temperature, and sea ice reconstructions from the ANDRILL AND-1B sediment core recovered from beneath the Ross Ice Shelf. We provide evidence for a major expansion of an ice sheet in the Ross Sea that began at ∼3.3 Ma, followed by a coastal sea surface temperature cooling of ∼2.5 °C, a stepwise expansion of sea ice, and polynya-style deep mixing in the Ross Sea between 3.3 and 2.5 Ma. The intensification of Antarctic cooling resulted in strengthened westerly winds and invigorated ocean circulation. The associated northward migration of Southern Ocean fronts has been linked with reduced Atlantic Meridional Overturning Circulation by restricting surface water connectivity between the ocean basins, with implications for heat transport to the high latitudes of the North Atlantic. While our results do not exclude low-latitude mechanisms as drivers for Pliocene cooling, they indicate an additional role played by southern high-latitude cooling during development of the bipolar world. PMID:22496594

  7. Air-sea interaction regimes in the sub-Antarctic Southern Ocean and Antarctic marginal ice zone revealed by icebreaker measurements

    NASA Astrophysics Data System (ADS)

    Yu, Lisan; Jin, Xiangze; Schulz, Eric W.; Josey, Simon A.

    2017-08-01

    This study analyzed shipboard air-sea measurements acquired by the icebreaker Aurora Australis during its off-winter operation in December 2010 to May 2012. Mean conditions over 7 months (October-April) were compiled from a total of 22 ship tracks. The icebreaker traversed the water between Hobart, Tasmania, and the Antarctic continent, providing valuable in situ insight into two dynamically important, yet poorly sampled, regimes: the sub-Antarctic Southern Ocean and the Antarctic marginal ice zone (MIZ) in the Indian Ocean sector. The transition from the open water to the ice-covered surface creates sharp changes in albedo, surface roughness, and air temperature, leading to consequential effects on air-sea variables and fluxes. Major effort was made to estimate the air-sea fluxes in the MIZ using the bulk flux algorithms that are tuned specifically for the sea-ice effects, while computing the fluxes over the sub-Antarctic section using the COARE3.0 algorithm. The study evidenced strong sea-ice modulations on winds, with the southerly airflow showing deceleration (convergence) in the MIZ and acceleration (divergence) when moving away from the MIZ. Marked seasonal variations in heat exchanges between the atmosphere and the ice margin were noted. The monotonic increase in turbulent latent and sensible heat fluxes after summer turned the MIZ quickly into a heat loss regime, while at the same time the sub-Antarctic surface water continued to receive heat from the atmosphere. The drastic increase in turbulent heat loss in the MIZ contrasted sharply to the nonsignificant and seasonally invariant turbulent heat loss over the sub-Antarctic open water.Plain Language SummaryThe icebreaker Aurora Australis is a research and supply vessel that is regularly chartered by the Australian <span class="hlt">Antarctic</span> Division during the <span class="hlt">southern</span> summer to operate in waters between Hobart, Tasmania, and Antarctica. The vessel serves as the main lifeline to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PalOc..32..674H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PalOc..32..674H"><span><span class="hlt">Antarctic</span> climate, <span class="hlt">Southern</span> <span class="hlt">Ocean</span> circulation patterns, and deep water formation during the Eocene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huck, Claire E.; van de Flierdt, Tina; Bohaty, Steven M.; Hammond, Samantha J.</p> <p>2017-07-01</p> <p>We assess early-to-middle Eocene seawater neodymium (Nd) isotope records from seven <span class="hlt">Southern</span> <span class="hlt">Ocean</span> deep-sea drill sites to evaluate the role of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> circulation in long-term Cenozoic climate change. Our study sites are strategically located on either side of the Tasman Gateway and are positioned at a range of shallow (<500 m) to intermediate/deep ( 1000-2500 m) paleowater depths. Unradiogenic seawater Nd isotopic compositions, reconstructed from fish teeth at intermediate/deep Indian <span class="hlt">Ocean</span> pelagic sites (<span class="hlt">Ocean</span> Drilling Program (ODP) Sites 738 and 757 and Deep Sea Drilling Project (DSDP) Site 264), indicate a dominant <span class="hlt">Southern</span> <span class="hlt">Ocean</span>-sourced contribution to regional deep waters (ɛNd(t) = -9.3 ± 1.5). IODP Site U1356 off the coast of Adélie Land, a locus of modern-day <span class="hlt">Antarctic</span> Bottom Water production, is identified as a site of persistent deep water formation from the early Eocene to the Oligocene. East of the Tasman Gateway an additional local source of intermediate/deep water formation is inferred at ODP Site 277 in the SW Pacific <span class="hlt">Ocean</span> (ɛNd(t) = -8.7 ± 1.5). <span class="hlt">Antarctic</span>-proximal shelf sites (ODP Site 1171 and Site U1356) reveal a pronounced erosional event between 49 and 48 Ma, manifested by 2 ɛNd unit negative excursions in seawater chemistry toward the composition of bulk sediments at these sites. This erosional event coincides with the termination of peak global warmth following the Early Eocene Climatic Optimum and is associated with documented cooling across the study region and increased export of <span class="hlt">Antarctic</span> deep waters, highlighting the complexity and importance of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> circulation in the greenhouse climate of the Eocene.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1918401P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1918401P"><span>Drivers of <span class="hlt">Antarctic</span> sea-ice expansion and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> surface cooling over the past four decades</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Purich, Ariaan; England, Matthew</p> <p>2017-04-01</p> <p>Despite global warming, total <span class="hlt">Antarctic</span> sea-ice coverage has increased overall during the past four decades. In contrast, the majority of CMIP5 models simulate a decline. In addition, <span class="hlt">Southern</span> <span class="hlt">Ocean</span> surface waters have largely cooled, in stark contrast to almost all historical CMIP5 simulations. Subantarctic Surface Waters have cooled and freshened while waters to the north of the <span class="hlt">Antarctic</span> Circumpolar Current have warmed and increased in salinity. It remains unclear as to what extent the cooling and <span class="hlt">Antarctic</span> sea-ice expansion is due to natural variability versus anthropogenic forcing; due for example to changes in the <span class="hlt">Southern</span> Annular Mode (SAM). It is also unclear what the respective role of surface buoyancy fluxes is compared to internal <span class="hlt">ocean</span> circulation changes, and what the implications are for longer-term climate change in the region. In this presentation we will outline three distinct drivers of recent <span class="hlt">Southern</span> <span class="hlt">Ocean</span> surface trends that have each made a significant contribution to regional cooling: (1) wind-driven surface cooling and sea-ice expansion due to shifted westerly winds, (2) teleconnections of decadal variability from the tropical Pacific, and (3) surface cooling and ice expansion due to large-scale <span class="hlt">Southern</span> <span class="hlt">Ocean</span> freshening, most likely driven by SAM-related precipitation trends over the open <span class="hlt">ocean</span>. We will also outline the main reasons why climate models for the most part miss these <span class="hlt">Southern</span> <span class="hlt">Ocean</span> cooling trends, despite capturing overall trends in the SAM.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMPA32A..07K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMPA32A..07K"><span>A Roadmap for <span class="hlt">Antarctic</span> and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Science for the Next Two Decades and Beyond</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kennicutt, M. C., II</p> <p>2015-12-01</p> <p>Abstract: <span class="hlt">Antarctic</span> and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> science is vital to understanding natural variability, the processes that govern global change and the role of humans in the Earth and climate system. The potential for new knowledge to be gained from future <span class="hlt">Antarctic</span> science is substantial. Therefore, the international <span class="hlt">Antarctic</span> community came together to 'scan the horizon' to identify the highest priority scientific questions that researchers should aspire to answer in the next two decades and beyond. Wide consultation was a fundamental principle for the development of a collective, international view of the most important future directions in <span class="hlt">Antarctic</span> science. From the many possibilities, the horizon scan identified 80 key scientific questions through structured debate, discussion, revision and voting. Questions were clustered into seven topics: i) <span class="hlt">Antarctic</span> atmosphere and global connections, ii) <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and sea ice in a warming world, iii) ice sheet and sea level, iv) the dynamic Earth, v) life on the precipice, vi) near-Earth space and beyond, and vii) human presence in Antarctica. Answering the questions identified by the horizon scan will require innovative experimental designs, novel applications of technology, invention of next-generation field and laboratory approaches, and expanded observing systems and networks. Unbiased, non-contaminating procedures will be required to retrieve the requisite air, biota, sediment, rock, ice and water samples. Sustained year-round access to Antarctica and the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> will be essential to increase winter-time measurements. Improved models are needed that represent Antarctica and the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in the Earth System, and provide predictions at spatial and temporal resolutions useful for decision making. A co-ordinated portfolio of cross-disciplinary science, based on new models of international collaboration, will be essential as no scientist, programme or nation can realize these aspirations alone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25263015','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25263015"><span><span class="hlt">Antarctic</span> contribution to meltwater pulse 1A from reduced <span class="hlt">Southern</span> <span class="hlt">Ocean</span> overturning.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Golledge, N R; Menviel, L; Carter, L; Fogwill, C J; England, M H; Cortese, G; Levy, R H</p> <p>2014-09-29</p> <p>During the last glacial termination, the upwelling strength of the <span class="hlt">southern</span> polar limb of the Atlantic Meridional Overturning Circulation varied, changing the ventilation and stratification of the high-latitude <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. During the same period, at least two phases of abrupt global sea-level rise--meltwater pulses--took place. Although the timing and magnitude of these events have become better constrained, a causal link between <span class="hlt">ocean</span> stratification, the meltwater pulses and accelerated ice loss from Antarctica has not been proven. Here we simulate <span class="hlt">Antarctic</span> ice sheet evolution over the last 25 kyr using a data-constrained ice-sheet model forced by changes in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> temperature from an Earth system model. Results reveal several episodes of accelerated ice-sheet recession, the largest being coincident with meltwater pulse 1A. This resulted from reduced <span class="hlt">Southern</span> <span class="hlt">Ocean</span> overturning following Heinrich Event 1, when warmer subsurface water thermally eroded grounded marine-based ice and instigated a positive feedback that further accelerated ice-sheet retreat.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMOS41D..06F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMOS41D..06F"><span>Impact of <span class="hlt">Antarctic</span> Polar Front Variability on <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Biogeochemistry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Freeman, N. M.; Lovenduski, N. S.; Gent, P. R.</p> <p>2016-12-01</p> <p>The <span class="hlt">Antarctic</span> Polar Front (PF) is an important biogeochemical divide in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, often coinciding with sharp gradients in silicate and nitrate concentration at the surface. Variability in the PF has the potential to influence <span class="hlt">Southern</span> <span class="hlt">Ocean</span> biogeochemistry and biological productivity both locally and at the basin scale. Characterizing PF variability is important for contextualizing recent biogeochemical observations from ORCAS, SOCCOM, and the Drake Passage time-series, as well as for understanding how anthropogenic change is influencing <span class="hlt">Southern</span> <span class="hlt">Ocean</span> biogeochemistry. Here, we employ a suite of remote sensing observations and output from the Community Earth System Model (CESM) to better understand the relationship between the PF and local biogeochemistry in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Using microwave SST measurements spanning 2002-2014 that avoid cloud contamination, we show that the PF has shifted northward (southward) in the Pacific (Indian) sector and intensified at nearly all longitudes along its circumpolar path. We identify the PF in CESM at both coarse (1°x1°) and fine (0.1°x0.1°) horizontal resolutions using temperature and silicate gradient maxima, and quantify its spatial and temporal variability. We further investigate co-variance between the position and intensity of the PF and local phytoplankton community structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28761090','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28761090"><span>Restricted regions of enhanced growth of <span class="hlt">Antarctic</span> krill in the circumpolar <span class="hlt">Southern</span> <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Murphy, Eugene J; Thorpe, Sally E; Tarling, Geraint A; Watkins, Jonathan L; Fielding, Sophie; Underwood, Philip</p> <p>2017-07-31</p> <p>Food webs in high-latitude <span class="hlt">oceans</span> are dominated by relatively few species. Future <span class="hlt">ocean</span> and sea-ice changes affecting the distribution of such species will impact the structure and functioning of whole ecosystems. <span class="hlt">Antarctic</span> krill (Euphausia superba) is a key species in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> food webs, but there is little understanding of the factors influencing its success throughout much of the <span class="hlt">ocean</span>. The capacity of a habitat to maintain growth will be crucial and here we use an empirical relationship of growth rate to assess seasonal spatial variability. Over much of the <span class="hlt">ocean</span>, potential for growth is limited, with three restricted <span class="hlt">oceanic</span> regions where seasonal conditions permit high growth rates, and only a few areas around the Scotia Sea and <span class="hlt">Antarctic</span> Peninsula suitable for growth of the largest krill (>60 mm). Our study demonstrates that projections of impacts of future change need to account for spatial and seasonal variability of key ecological processes within <span class="hlt">ocean</span> ecosystems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170002562','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170002562"><span>Impacts of Interactive Stratospheric Chemistry on <span class="hlt">Antarctic</span> and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Climate Change in the Goddard Earth Observing System Version 5 (GEOS-5)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Li, Feng; Vikhliaev, Yury V.; Newman, Paul A.; Pawson, Steven; Perlwitz, Judith; Waugh, Darryn W.; Douglass, Anne R.</p> <p>2016-01-01</p> <p>Stratospheric ozone depletion plays a major role in driving climate change in the <span class="hlt">Southern</span> Hemisphere. To date, many climate models prescribe the stratospheric ozone layer's evolution using monthly and zonally averaged ozone fields. However, the prescribed ozone underestimates <span class="hlt">Antarctic</span> ozone depletion and lacks zonal asymmetries. In this study we investigate the impact of using interactive stratospheric chemistry instead of prescribed ozone on climate change simulations of the <span class="hlt">Antarctic</span> and <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Two sets of 1960-2010 ensemble transient simulations are conducted with the coupled <span class="hlt">ocean</span> version of the Goddard Earth Observing System Model, version 5: one with interactive stratospheric chemistry and the other with prescribed ozone derived from the same interactive simulations. The model's climatology is evaluated using observations and reanalysis. Comparison of the 1979-2010 climate trends between these two simulations reveals that interactive chemistry has important effects on climate change not only in the <span class="hlt">Antarctic</span> stratosphere, troposphere, and surface, but also in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and <span class="hlt">Antarctic</span> sea ice. Interactive chemistry causes stronger <span class="hlt">Antarctic</span> lower stratosphere cooling and circumpolar westerly acceleration during November-December-January. It enhances stratosphere-troposphere coupling and leads to significantly larger tropospheric and surface westerly changes. The significantly stronger surface wind stress trends cause larger increases of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Meridional Overturning Circulation, leading to year-round stronger <span class="hlt">ocean</span> warming near the surface and enhanced <span class="hlt">Antarctic</span> sea ice decrease.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMOS13A2019R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS13A2019R"><span>The Biogeochemical Role of <span class="hlt">Antarctic</span> Krill and Baleen Whales in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Nutrient Cycling.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ratnarajah, L.</p> <p>2015-12-01</p> <p>Iron limits primary productivity in large areas of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. It has been suggested that baleen whales form a crucial part of biogeochemical cycling processes through the consumption of nutrient-rich krill and subsequent defecation, but evidence on their contribution is scarce. We analysed the concentration of iron in <span class="hlt">Antarctic</span> krill and baleen whale faeces and muscle. Iron concentrations in <span class="hlt">Antarctic</span> krill were over 1 million times higher, and whale faecal matter were almost 10 million times higher than typical <span class="hlt">Southern</span> <span class="hlt">Ocean</span> High Nutrient Low Chlorophyll seawater concentrations. This suggests that <span class="hlt">Antarctic</span> krill act as a reservoir of in in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> surface waters, and that baleen whales play an important role in converting this fixed iron into a liquid form in their faeces. We developed an exploratory model to examine potential contribution of blue, fin and humpback whales to the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> iron cycle to explore the effect of the recovery of great whales to historical levels. Our results suggest that pre-exploitation populations of blue whales and, to a lesser extent fin and humpback whales, could have contributed to the more effective recycling of iron in surface waters, resulting in enhanced phytoplankton production. This enhanced primary productivity is estimated to be: 8.3 x 10-5 to 15 g C m-2 yr-1 (blue whales), 7 x 10-5 to 9 g C m-2 yr-1 (fin whales), and 10-5 to 1.7 g C m-2 yr-1 (humpback whales). To put these into perspective, current estimates of primary production in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> from remotely sensed <span class="hlt">ocean</span> colour are in the order of 57 g C m-2 yr-1 (south of 50°). The high degree of uncertainty around the magnitude of these increases in primary productivity is mainly due to our limited quantitative understanding of key biogeochemical processes including iron content in krill, krill consumption rates by whales, persistence of iron in the photic zone, bioavailability of retained iron, and carbon-to-iron ratio of phytoplankton</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2914006','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2914006"><span><span class="hlt">Antarctic</span> Marine Biodiversity – What Do We Know About the Distribution of Life in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>?</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Griffiths, Huw J.</p> <p>2010-01-01</p> <p>The remote and hostile <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is home to a diverse and rich community of life that thrives in an environment dominated by glaciations and strong currents. Marine biological studies in the region date back to the nineteenth century, but despite this long history of research, relatively little is known about the complex interactions between the highly seasonal physical environment and the species that inhabit the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Oceanographically, the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is a major driver of global <span class="hlt">ocean</span> circulation and plays a vital role in interacting with the deep water circulation in each of the Pacific, Atlantic, and Indian <span class="hlt">oceans</span>. The Census of <span class="hlt">Antarctic</span> Marine Life and the Scientific Committee on <span class="hlt">Antarctic</span> Research Marine Biodiversity Information Network (SCAR-MarBIN) have strived to coordinate and unify the available scientific expertise and biodiversity data to improve our understanding of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> biodiversity. Taxonomic lists for all marine species have been compiled to form the Register of <span class="hlt">Antarctic</span> Marine Species, which currently includes over 8,200 species. SCAR-MarBIN has brought together over 1 million distribution records for <span class="hlt">Southern</span> <span class="hlt">Ocean</span> species, forming a baseline against which future change can be judged. The sample locations and numbers of known species from different regions were mapped and the depth distributions of benthic samples plotted. Our knowledge of the biodiversity of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is largely determined by the relative inaccessibility of the region. Benthic sampling is largely restricted to the shelf; little is known about the fauna of the deep sea. The location of scientific bases heavily influences the distribution pattern of sample and observation data, and the logistical supply routes are the focus of much of the at-sea and pelagic work. Taxa such as mollusks and echinoderms are well represented within existing datasets with high numbers of georeferenced records. Other taxa, including the species-rich nematodes, are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24891389','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24891389"><span><span class="hlt">Ocean</span> processes at the <span class="hlt">Antarctic</span> continental slope.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Heywood, Karen J; Schmidtko, Sunke; Heuzé, Céline; Kaiser, Jan; Jickells, Timothy D; Queste, Bastien Y; Stevens, David P; Wadley, Martin; Thompson, Andrew F; Fielding, Sophie; Guihen, Damien; Creed, Elizabeth; Ridley, Jeff K; Smith, Walker</p> <p>2014-07-13</p> <p>The <span class="hlt">Antarctic</span> continental shelves and slopes occupy relatively small areas, but, nevertheless, are important for global climate, biogeochemical cycling and ecosystem functioning. Processes of water mass transformation through sea ice formation/melting and <span class="hlt">ocean</span>-atmosphere interaction are key to the formation of deep and bottom waters as well as determining the heat flux beneath ice shelves. Climate models, however, struggle to capture these physical processes and are unable to reproduce water mass properties of the region. Dynamics at the continental slope are key for correctly modelling climate, yet their small spatial scale presents challenges both for <span class="hlt">ocean</span> modelling and for observational studies. Cross-slope exchange processes are also vital for the flux of nutrients such as iron from the continental shelf into the mixed layer of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. An iron-cycling model embedded in an eddy-permitting <span class="hlt">ocean</span> model reveals the importance of sedimentary iron in fertilizing parts of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. <span class="hlt">Ocean</span> gliders play a key role in improving our ability to observe and understand these small-scale processes at the continental shelf break. The Gliders: Excellent New Tools for Observing the <span class="hlt">Ocean</span> (GENTOO) project deployed three Seagliders for up to two months in early 2012 to sample the water to the east of the <span class="hlt">Antarctic</span> Peninsula in unprecedented temporal and spatial detail. The glider data resolve small-scale exchange processes across the shelf-break front (the <span class="hlt">Antarctic</span> Slope Front) and the front's biogeochemical signature. GENTOO demonstrated the capability of <span class="hlt">ocean</span> gliders to play a key role in a future multi-disciplinary <span class="hlt">Southern</span> <span class="hlt">Ocean</span> observing system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5266476','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5266476"><span>Accelerated freshening of <span class="hlt">Antarctic</span> Bottom Water over the last decade in the <span class="hlt">Southern</span> Indian <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Menezes, Viviane V.; Macdonald, Alison M.; Schatzman, Courtney</p> <p>2017-01-01</p> <p><span class="hlt">Southern</span> <span class="hlt">Ocean</span> abyssal waters, in contact with the atmosphere at their formation sites around Antarctica, not only bring signals of a changing climate with them as they move around the globe but also contribute to that change through heat uptake and sea level rise. A repeat hydrographic line in the Indian sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, occupied three times in the last two decades (1994, 2007, and, most recently, 2016), reveals that <span class="hlt">Antarctic</span> Bottom Water (AABW) continues to become fresher (0.004 ± 0.001 kg/g decade−1), warmer (0.06° ± 0.01°C decade−1), and less dense (0.011 ± 0.002 kg/m3 decade−1). The most recent observations in the Australian-<span class="hlt">Antarctic</span> Basin show a particularly striking acceleration in AABW freshening between 2007 and 2016 (0.008 ± 0.001 kg/g decade−1) compared to the 0.002 ± 0.001 kg/g decade−1 seen between 1994 and 2007. Freshening is, in part, responsible for an overall shift of the mean temperature-salinity curve toward lower densities. The marked freshening may be linked to an abrupt iceberg-glacier collision and calving event that occurred in 2010 on the George V/Adélie Land Coast, the main source region of bottom waters for the Australian-<span class="hlt">Antarctic</span> Basin. Because AABW is a key component of the global overturning circulation, the persistent decrease in bottom water density and the associated increase in steric height that result from continued warming and freshening have important consequences beyond the <span class="hlt">Southern</span> Indian <span class="hlt">Ocean</span>. PMID:28138548</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28138548','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28138548"><span>Accelerated freshening of <span class="hlt">Antarctic</span> Bottom Water over the last decade in the <span class="hlt">Southern</span> Indian <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Menezes, Viviane V; Macdonald, Alison M; Schatzman, Courtney</p> <p>2017-01-01</p> <p><span class="hlt">Southern</span> <span class="hlt">Ocean</span> abyssal waters, in contact with the atmosphere at their formation sites around Antarctica, not only bring signals of a changing climate with them as they move around the globe but also contribute to that change through heat uptake and sea level rise. A repeat hydrographic line in the Indian sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, occupied three times in the last two decades (1994, 2007, and, most recently, 2016), reveals that <span class="hlt">Antarctic</span> Bottom Water (AABW) continues to become fresher (0.004 ± 0.001 kg/g decade -1 ), warmer (0.06° ± 0.01°C decade -1 ), and less dense (0.011 ± 0.002 kg/m 3 decade -1 ). The most recent observations in the Australian-<span class="hlt">Antarctic</span> Basin show a particularly striking acceleration in AABW freshening between 2007 and 2016 (0.008 ± 0.001 kg/g decade -1 ) compared to the 0.002 ± 0.001 kg/g decade -1 seen between 1994 and 2007. Freshening is, in part, responsible for an overall shift of the mean temperature-salinity curve toward lower densities. The marked freshening may be linked to an abrupt iceberg-glacier collision and calving event that occurred in 2010 on the George V/Adélie Land Coast, the main source region of bottom waters for the Australian-<span class="hlt">Antarctic</span> Basin. Because AABW is a key component of the global overturning circulation, the persistent decrease in bottom water density and the associated increase in steric height that result from continued warming and freshening have important consequences beyond the <span class="hlt">Southern</span> Indian <span class="hlt">Ocean</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4032510','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4032510"><span><span class="hlt">Ocean</span> processes at the <span class="hlt">Antarctic</span> continental slope</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Heywood, Karen J.; Schmidtko, Sunke; Heuzé, Céline; Kaiser, Jan; Jickells, Timothy D.; Queste, Bastien Y.; Stevens, David P.; Wadley, Martin; Thompson, Andrew F.; Fielding, Sophie; Guihen, Damien; Creed, Elizabeth; Ridley, Jeff K.; Smith, Walker</p> <p>2014-01-01</p> <p>The <span class="hlt">Antarctic</span> continental shelves and slopes occupy relatively small areas, but, nevertheless, are important for global climate, biogeochemical cycling and ecosystem functioning. Processes of water mass transformation through sea ice formation/melting and ocean–atmosphere interaction are key to the formation of deep and bottom waters as well as determining the heat flux beneath ice shelves. Climate models, however, struggle to capture these physical processes and are unable to reproduce water mass properties of the region. Dynamics at the continental slope are key for correctly modelling climate, yet their small spatial scale presents challenges both for <span class="hlt">ocean</span> modelling and for observational studies. Cross-slope exchange processes are also vital for the flux of nutrients such as iron from the continental shelf into the mixed layer of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. An iron-cycling model embedded in an eddy-permitting <span class="hlt">ocean</span> model reveals the importance of sedimentary iron in fertilizing parts of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. <span class="hlt">Ocean</span> gliders play a key role in improving our ability to observe and understand these small-scale processes at the continental shelf break. The Gliders: Excellent New Tools for Observing the <span class="hlt">Ocean</span> (GENTOO) project deployed three Seagliders for up to two months in early 2012 to sample the water to the east of the <span class="hlt">Antarctic</span> Peninsula in unprecedented temporal and spatial detail. The glider data resolve small-scale exchange processes across the shelf-break front (the <span class="hlt">Antarctic</span> Slope Front) and the front's biogeochemical signature. GENTOO demonstrated the capability of <span class="hlt">ocean</span> gliders to play a key role in a future multi-disciplinary <span class="hlt">Southern</span> <span class="hlt">Ocean</span> observing system. PMID:24891389</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li class="active"><span>1</span></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_1 --> <div id="page_2" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li class="active"><span>2</span></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="21"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013NatCC...3..843K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013NatCC...3..843K"><span>Risk maps for <span class="hlt">Antarctic</span> krill under projected <span class="hlt">Southern</span> <span class="hlt">Ocean</span> acidification</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kawaguchi, S.; Ishida, A.; King, R.; Raymond, B.; Waller, N.; Constable, A.; Nicol, S.; Wakita, M.; Ishimatsu, A.</p> <p>2013-09-01</p> <p>Marine ecosystems of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> are particularly vulnerable to <span class="hlt">ocean</span> acidification. <span class="hlt">Antarctic</span> krill (Euphausia superba; hereafter krill) is the key pelagic species of the region and its largest fishery resource. There is therefore concern about the combined effects of climate change, <span class="hlt">ocean</span> acidification and an expanding fishery on krill and ultimately, their dependent predators--whales, seals and penguins. However, little is known about the sensitivity of krill to <span class="hlt">ocean</span> acidification. Juvenile and adult krill are already exposed to variable seawater carbonate chemistry because they occupy a range of habitats and migrate both vertically and horizontally on a daily and seasonal basis. Moreover, krill eggs sink from the surface to hatch at 700-1,000m (ref. ), where the carbon dioxide partial pressure (pCO2) in sea water is already greater than it is in the atmosphere. Krill eggs sink passively and so cannot avoid these conditions. Here we describe the sensitivity of krill egg hatch rates to increased CO2, and present a circumpolar risk map of krill hatching success under projected pCO2 levels. We find that important krill habitats of the Weddell Sea and the Haakon VII Sea to the east are likely to become high-risk areas for krill recruitment within a century. Furthermore, unless CO2 emissions are mitigated, the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> krill population could collapse by 2300 with dire consequences for the entire ecosystem.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018OcMod.121...76M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018OcMod.121...76M"><span>Impact of increasing <span class="hlt">antarctic</span> glacial freshwater release on regional sea-ice cover in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Merino, Nacho; Jourdain, Nicolas C.; Le Sommer, Julien; Goosse, Hugues; Mathiot, Pierre; Durand, Gael</p> <p>2018-01-01</p> <p>The sensitivity of <span class="hlt">Antarctic</span> sea-ice to increasing glacial freshwater release into the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is studied in a series of 31-year <span class="hlt">ocean</span>/sea-ice/iceberg model simulations. Glaciological estimates of ice-shelf melting and iceberg calving are used to better constrain the spatial distribution and magnitude of freshwater forcing around Antarctica. Two scenarios of glacial freshwater forcing have been designed to account for a decadal perturbation in glacial freshwater release to the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. For the first time, this perturbation explicitly takes into consideration the spatial distribution of changes in the volume of <span class="hlt">Antarctic</span> ice shelves, which is found to be a key component of changes in freshwater release. In addition, glacial freshwater-induced changes in sea ice are compared to typical changes induced by the decadal evolution of atmospheric states. Our results show that, in general, the increase in glacial freshwater release increases <span class="hlt">Antarctic</span> sea ice extent. But the response is opposite in some regions like the coastal Amundsen Sea, implying that distinct physical mechanisms are involved in the response. We also show that changes in freshwater forcing may induce large changes in sea-ice thickness, explaining about one half of the total change due to the combination of atmospheric and freshwater changes. The regional contrasts in our results suggest a need for improving the representation of freshwater sources and their evolution in climate models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMPP23A1382H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMPP23A1382H"><span><span class="hlt">Ocean</span> export production and foraminiferal stable isotopes in the <span class="hlt">Antarctic</span> <span class="hlt">Southern</span> <span class="hlt">Ocean</span> across the mid-Pleistocene transition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hasenfratz, A. P.; Martinez-Garcia, A.; Jaccard, S.; Hodell, D. A.; Vance, D.; Bernasconi, S. M.; Greaves, M.; Haug, G. H.</p> <p>2014-12-01</p> <p>Changes in buoyancy forcing in the <span class="hlt">Antarctic</span> Zone (AZ) of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> are believed to play an instrumental role in modulating atmospheric CO2 concentrations during glacial cycles by regulating the transfer of carbon between the <span class="hlt">ocean</span> interior and the atmosphere. Indeed, a million-year-spanning high-resolution excess Barium record from the AZ of the South Atlantic (ODP 1094), which traces changes in export production, shows decreased export production during cold periods suggesting decreased overturning. Here, we extend this AZ export production record back to 1.6 Myr. In addition, we present new carbon and oxygen isotope records of benthic and planktic foraminifera from the same site, complemented by Mg/Ca measurements in some intervals. The interpretation of these new data in the context of other South Atlantic records contributes to a better understanding of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> hydrography and its role in modulating glacial/interglacial cycles over the past 1.6 Myr.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140010545','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140010545"><span>Impacts of Atmosphere-<span class="hlt">Ocean</span> Coupling on <span class="hlt">Southern</span> Hemisphere Climate Change</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Li, Feng; Newman, Paul; Pawson, Steven</p> <p>2013-01-01</p> <p>Climate in the <span class="hlt">Southern</span> Hemisphere (SH) has undergone significant changes in recent decades. These changes are closely linked to the shift of the <span class="hlt">Southern</span> Annular Mode (SAM) towards its positive polarity, which is driven primarily by <span class="hlt">Antarctic</span> ozone depletion. There is growing evidence that <span class="hlt">Antarctic</span> ozone depletion has significant impacts on <span class="hlt">Southern</span> <span class="hlt">Ocean</span> circulation change. However, it is poorly understood whether and how <span class="hlt">ocean</span> feedback might impact the SAM and climate change in the SH atmosphere. This outstanding science question is investigated using the Goddard Earth Observing System Coupled Atmosphere-<span class="hlt">Ocean</span>-Chemistry Climate Model(GEOS-AOCCM).We perform ensemble simulations of the recent past (1960-2010) with and without the interactive <span class="hlt">ocean</span>. For simulations without the interactive <span class="hlt">ocean</span>, we use sea surface temperatures and sea ice concentrations produced by the interactive <span class="hlt">ocean</span> simulations. The differences between these two ensemble simulations quantify the effects of atmosphere-<span class="hlt">ocean</span> coupling. We will investigate the impacts of atmosphere-<span class="hlt">ocean</span> coupling on stratospheric processes such as <span class="hlt">Antarctic</span> ozone depletion and <span class="hlt">Antarctic</span> polar vortex breakup. We will address whether <span class="hlt">ocean</span> feedback affects Rossby wave generation in the troposphere and wave propagation into the stratosphere. Another focuson this study is to assess how <span class="hlt">ocean</span> feedback might affect the tropospheric SAM response to <span class="hlt">Antarctic</span> ozone depletion</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3749108','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3749108"><span>Potential Climate Change Effects on the Habitat of <span class="hlt">Antarctic</span> Krill in the Weddell Quadrant of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hill, Simeon L.; Phillips, Tony; Atkinson, Angus</p> <p>2013-01-01</p> <p><span class="hlt">Antarctic</span> krill is a cold water species, an increasingly important fishery resource and a major prey item for many fish, birds and mammals in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. The fishery and the summer foraging sites of many of these predators are concentrated between 0° and 90°W. Parts of this quadrant have experienced recent localised sea surface warming of up to 0.2°C per decade, and projections suggest that further widespread warming of 0.27° to 1.08°C will occur by the late 21st century. We assessed the potential influence of this projected warming on <span class="hlt">Antarctic</span> krill habitat with a statistical model that links growth to temperature and chlorophyll concentration. The results divide the quadrant into two zones: a band around the <span class="hlt">Antarctic</span> Circumpolar Current in which habitat quality is particularly vulnerable to warming, and a <span class="hlt">southern</span> area which is relatively insensitive. Our analysis suggests that the direct effects of warming could reduce the area of growth habitat by up to 20%. The reduction in growth habitat within the range of predators, such as <span class="hlt">Antarctic</span> fur seals, that forage from breeding sites on South Georgia could be up to 55%, and the habitat’s ability to support <span class="hlt">Antarctic</span> krill biomass production within this range could be reduced by up to 68%. Sensitivity analysis suggests that the effects of a 50% change in summer chlorophyll concentration could be more significant than the direct effects of warming. A reduction in primary production could lead to further habitat degradation but, even if chlorophyll increased by 50%, projected warming would still cause some degradation of the habitat accessible to predators. While there is considerable uncertainty in these projections, they suggest that future climate change could have a significant negative effect on <span class="hlt">Antarctic</span> krill growth habitat and, consequently, on <span class="hlt">Southern</span> <span class="hlt">Ocean</span> biodiversity and ecosystem services. PMID:23991072</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23991072','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23991072"><span>Potential climate change effects on the habitat of <span class="hlt">antarctic</span> krill in the weddell quadrant of the <span class="hlt">southern</span> <span class="hlt">ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hill, Simeon L; Phillips, Tony; Atkinson, Angus</p> <p>2013-01-01</p> <p><span class="hlt">Antarctic</span> krill is a cold water species, an increasingly important fishery resource and a major prey item for many fish, birds and mammals in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. The fishery and the summer foraging sites of many of these predators are concentrated between 0° and 90°W. Parts of this quadrant have experienced recent localised sea surface warming of up to 0.2°C per decade, and projections suggest that further widespread warming of 0.27° to 1.08°C will occur by the late 21(st) century. We assessed the potential influence of this projected warming on <span class="hlt">Antarctic</span> krill habitat with a statistical model that links growth to temperature and chlorophyll concentration. The results divide the quadrant into two zones: a band around the <span class="hlt">Antarctic</span> Circumpolar Current in which habitat quality is particularly vulnerable to warming, and a <span class="hlt">southern</span> area which is relatively insensitive. Our analysis suggests that the direct effects of warming could reduce the area of growth habitat by up to 20%. The reduction in growth habitat within the range of predators, such as <span class="hlt">Antarctic</span> fur seals, that forage from breeding sites on South Georgia could be up to 55%, and the habitat's ability to support <span class="hlt">Antarctic</span> krill biomass production within this range could be reduced by up to 68%. Sensitivity analysis suggests that the effects of a 50% change in summer chlorophyll concentration could be more significant than the direct effects of warming. A reduction in primary production could lead to further habitat degradation but, even if chlorophyll increased by 50%, projected warming would still cause some degradation of the habitat accessible to predators. While there is considerable uncertainty in these projections, they suggest that future climate change could have a significant negative effect on <span class="hlt">Antarctic</span> krill growth habitat and, consequently, on <span class="hlt">Southern</span> <span class="hlt">Ocean</span> biodiversity and ecosystem services.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998Natur.392..708T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998Natur.392..708T"><span>Ecological importance of the <span class="hlt">Southern</span> Boundary of the <span class="hlt">Antarctic</span> Circumpolar Current</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tynan, Cynthia T.</p> <p>1998-04-01</p> <p>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> surrounds the <span class="hlt">Antarctic</span> continent and supports one of the most productive marine ecosystems. Migratory and endemic species of whales, seals and birds benefit from the high biomass of their principal prey, krill (Euphausia superba) and cephalopods, in this area. Most species of baleen whales and male sperm whales in the <span class="hlt">Southern</span> Hemisphere migrate between low-latitude breeding grounds in winter and highly productive <span class="hlt">Antarctic</span> feeding grounds in summer. Here I show the importance of the southernmost reaches of the strongest <span class="hlt">ocean</span> current, the <span class="hlt">Antarctic</span> Circumpolar Current (ACC), to a complex and predictable food web of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. The circumpolar distributions of blue, fin and humpback whales from spring to midsummer trace the non-uniform high-latitude penetration of shoaled, nutrient-rich Upper Circumpolar Deep Water, which is carried eastward by the ACC. The poleward extent of this water mass delineates the <span class="hlt">Southern</span> Boundary of the ACC and corresponds not only to the circumpolar distributions of baleen whales, but also to distributions of krill and to regions of high, seasonally averaged, phytoplankton biomass. Sperm whales, which feed on cephalopods, also congregate in highest densities near the <span class="hlt">Southern</span> Boundary. The association of primary production, Krill, and whales with the <span class="hlt">Southern</span> Boundary, suggests that it provides predictably productive foraging for many species, and is of critical importance to the function of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ecosystem.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4922175','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4922175"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> phytoplankton turnover in response to stepwise <span class="hlt">Antarctic</span> cooling over the past 15 million years</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Crampton, James S.; Cody, Rosie D.; Levy, Richard; Harwood, David; McKay, Robert; Naish, Tim R.</p> <p>2016-01-01</p> <p>It is not clear how <span class="hlt">Southern</span> <span class="hlt">Ocean</span> phytoplankton communities, which form the base of the marine food web and are a crucial element of the carbon cycle, respond to major environmental disturbance. Here, we use a new model ensemble reconstruction of diatom speciation and extinction rates to examine phytoplankton response to climate change in the <span class="hlt">southern</span> high latitudes over the past 15 My. We identify five major episodes of species turnover (origination rate plus extinction rate) that were coincident with times of cooling in <span class="hlt">southern</span> high-latitude climate, <span class="hlt">Antarctic</span> ice sheet growth across the continental shelves, and associated seasonal sea-ice expansion across the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. We infer that past plankton turnover occurred when a warmer-than-present climate was terminated by a major period of glaciation that resulted in loss of open-<span class="hlt">ocean</span> habitat south of the polar front, driving non-ice adapted diatoms to regional or global extinction. These findings suggest, therefore, that <span class="hlt">Southern</span> <span class="hlt">Ocean</span> phytoplankton communities tolerate “baseline” variability on glacial–interglacial timescales but are sensitive to large-scale changes in mean climate state driven by a combination of long-period variations in orbital forcing and atmospheric carbon dioxide perturbations. PMID:27274061</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PNAS..113.6868C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PNAS..113.6868C"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> phytoplankton turnover in response to stepwise <span class="hlt">Antarctic</span> cooling over the past 15 million years</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Crampton, James S.; Cody, Rosie D.; Levy, Richard; Harwood, David; McKay, Robert; Naish, Tim R.</p> <p>2016-06-01</p> <p>It is not clear how <span class="hlt">Southern</span> <span class="hlt">Ocean</span> phytoplankton communities, which form the base of the marine food web and are a crucial element of the carbon cycle, respond to major environmental disturbance. Here, we use a new model ensemble reconstruction of diatom speciation and extinction rates to examine phytoplankton response to climate change in the <span class="hlt">southern</span> high latitudes over the past 15 My. We identify five major episodes of species turnover (origination rate plus extinction rate) that were coincident with times of cooling in <span class="hlt">southern</span> high-latitude climate, <span class="hlt">Antarctic</span> ice sheet growth across the continental shelves, and associated seasonal sea-ice expansion across the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. We infer that past plankton turnover occurred when a warmer-than-present climate was terminated by a major period of glaciation that resulted in loss of open-<span class="hlt">ocean</span> habitat south of the polar front, driving non-ice adapted diatoms to regional or global extinction. These findings suggest, therefore, that <span class="hlt">Southern</span> <span class="hlt">Ocean</span> phytoplankton communities tolerate “baseline” variability on glacial-interglacial timescales but are sensitive to large-scale changes in mean climate state driven by a combination of long-period variations in orbital forcing and atmospheric carbon dioxide perturbations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.T31C0635S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.T31C0635S"><span>U-Series Disequilibria across the New <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Mantle Province, Australian-<span class="hlt">Antarctic</span> Ridge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scott, S. R.; Sims, K. W. W.; Park, S. H.; Langmuir, C. H.; Lin, J.; Kim, S. S.; Blichert-Toft, J.; Michael, P. J.; Choi, H.; Yang, Y. S.</p> <p>2017-12-01</p> <p>Mid-<span class="hlt">ocean</span> ridge basalts (MORB) provide a unique window into the temporal and spatial scales of mantle evolution. Long-lived radiogenic isotopes in MORB have demonstrated that the mantle contains many different chemical components or "flavors". U-series disequilibria in MORB have further shown that different chemical components/lithologies in the mantle contribute differently to mantle melting processes beneath mid-<span class="hlt">ocean</span> ridges. Recent Sr, Nd, Hf, and Pb isotopic analyses from newly collected basalts along the Australian-<span class="hlt">Antarctic</span> Ridge (AAR) have revealed that a large distinct mantle province exists between the Australian-<span class="hlt">Antarctic</span> Discordance and the Pacific-<span class="hlt">Antarctic</span> Ridge, extending from West Antarctica and Marie Byrd Land to New Zealand and Eastern Australia (Park et al., submitted). This <span class="hlt">southern</span> mantle province is located between the Indian-type mantle and the Pacific-type mantle domains. U-series measurements in the Southeast Indian Ridge and East Pacific Rise provinces show distinct signatures suggestive of differences in melting processes and source lithology. To examine whether the AAR mantle province also exhibits different U-series systematics we have measured U-Th-Ra disequilibria data on 38 basalts from the AAR sampled along 500 km of ridge axis from two segments that cross the newly discovered <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Mantle province. We compare the data to those from nearby ridge segments show that the AAR possesses unique U-series disequilibria, and are thus undergoing distinct mantle melting dynamics relative to the adjacent Pacific and Indian ridges. (230Th)/(238U) excesses in zero-age basalts (i.e., those with (226Ra)/(230Th) > 1.0) range from 1.3 to 1.7, while (226Ra)/(230Th) ranges from 1.0 to 2.3. (226Ra)/(230Th) and (230Th)/(238U) are negatively correlated, consistent with the model of mixing between deep and shallow melts. The AAR data show higher values of disequilibria compared to the Indian and Pacific Ridges, which can be explained by either</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMPP23A1373S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMPP23A1373S"><span><span class="hlt">Antarctic</span> <span class="hlt">Ocean</span> Nutrient Conditions During the Last Two Glacial Cycles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Studer, A.; Sigman, D. M.; Martinez-Garcia, A.; Benz, V.; Winckler, G.; Kuhn, G.; Esper, O.; Lamy, F.; Jaccard, S.; Wacker, L.; Oleynik, S.; Gersonde, R.; Haug, G. H.</p> <p>2014-12-01</p> <p>The high concentration of the major nutrients nitrate and phosphate in the <span class="hlt">Antarctic</span> Zone of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> dictates the nature of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ecosystems and permits these nutrients to be carried from the deep <span class="hlt">ocean</span> into the nutrient-limited low latitudes. Incomplete nutrient consumption in the <span class="hlt">Antarctic</span> also allows the leakage of deeply sequestered carbon dioxide (CO2) back to the atmosphere, and changes in this leakage may have driven glacial/interglacial cycles in atmospheric CO2. In a sediment core from the Pacific sector of the <span class="hlt">Antarctic</span> <span class="hlt">Ocean</span>, we report diatom-bound N isotope (δ15Ndb) records for total recoverable diatoms and two assemblages of diatom species. These data indicate tight coupling between the degree of nitrate consumption and <span class="hlt">Antarctic</span> climate across the last two glacial cycles, with δ15Ndb (and thus the degree of nitrate consumption) increasing at each major <span class="hlt">Antarctic</span> cooling event. Measurements in the same sediment core indicate that export production was reduced during ice ages, pointing to an ice age reduction in the supply of deep <span class="hlt">ocean</span>-sourced nitrate to the <span class="hlt">Antarctic</span> <span class="hlt">Ocean</span> surface. The reduced export production of peak ice ages also implies a weaker winter-to-summer decline (i.e. reduced seasonality) in mixed layer nitrate concentration, providing a plausible explanation for an observed reduction in the inter-assemblage δ15Ndb difference during these coldest times. Despite the weak summertime productivity, the reduction in wintertime nitrate supply from deep waters left the <span class="hlt">Antarctic</span> mixed layer with a low nitrate concentration, and this wintertime change also would have reduced the outgassing of CO2. Relief of light limitation fails to explain the intermediate degree of nitrate consumption that characterizes early glacial conditions, as improved light limitation coincident with reduced nitrate supply would drive nitrate consumption to completion. Thus, the data favor iron availability as the dominant control on annual <span class="hlt">Antarctic</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMPP34B..04H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMPP34B..04H"><span>Evolution of surface and deep water conditions in the <span class="hlt">Antarctic</span> <span class="hlt">Southern</span> <span class="hlt">Ocean</span> across the MPT</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hasenfratz, A. P.; Jaccard, S.; Martinez-Garcia, A.; Hodell, D. A.; Vance, D.; Bernasconi, S. M.; Kleiven, H. F.; Haug, G. H.</p> <p>2016-12-01</p> <p>The mid-Pleistocene transition (MPT; 1.25-0.7 Myr) marked a fundamental change in the periodicity of the climate cycles, shifting from a 41-kyr to a high-amplitude, asymmetric 100-kyr cycle without any noticeable change in orbital forcing. Hypotheses to explain the MPT involve non-linear responses to orbital forcing, changes in glacial dynamics and internal changes in the carbon cycle. Specifically, a decrease in pCO2 during peak ice age conditions and the associated global cooling has been proposed as one of the possible triggers for the MPT. Previous results have indicated that the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> provides a coherent two-part mechanism for the timing and amplitude of the glacial/interglacial pCO2 variations. However, there is still much uncertainty and debate regarding the response of the <span class="hlt">Antarctic</span> <span class="hlt">Southern</span> <span class="hlt">Ocean</span> biogeochemistry to changes invoked for the MPT, and its contribution to the proposed pCO2 variations. Here, we show 1.5 Myr-long records of export production, and planktonic (Neogloboquadrina pachyderma) and benthic (Melonis pompilioides) foraminiferal stable isotopes and trace metals from ODP Site 1094 retrieved from the Atlantic sector of the <span class="hlt">Antarctic</span> <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (53.2°S, 5.1°E, 2807m). While glacial planktonic δ18O increases across the MPT, glacial Mg/Ca-derived SST decrease later, around 700 ka, when glacial atmospheric pCO2 has already dropped. As glacial export production that is crucially related to micronutrients upwelled from the subsurface <span class="hlt">ocean</span> remains unchanged across the past 1.5 Myr, it seems that cooling of the glacial surface <span class="hlt">ocean</span> did not significantly alter the stability of the water column. Furthermore, paired measurements of benthic δ18O and Mg/Ca enables the determination of seawater δ18O of the deep <span class="hlt">ocean</span>, which allows us to estimate changes in the density gradient and the salinity of the deep water.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017DSRII.138....1S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017DSRII.138....1S"><span>Eddy-Pump: Pelagic carbon pump processes along the eddying <span class="hlt">Antarctic</span> Polar Front in the Atlantic Sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Strass, Volker H.; Wolf-Gladrow, Dieter; Pakhomov, Evgeny A.; Klaas, Christine</p> <p>2017-04-01</p> <p>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> influences earth's climate in many ways. It hosts the largest upwelling region of the world <span class="hlt">oceans</span> where 80% of deep waters resurface (Morrison et al., 2015). A prominent feature is the broad ring of cold water, the <span class="hlt">Antarctic</span> Circumpolar Current (ACC), which encircles the <span class="hlt">Antarctic</span> continent and connects all other <span class="hlt">oceans</span>. The ACC plays a major role in the global heat and freshwater transports and <span class="hlt">ocean</span>-wide cycles of chemical and biogenic elements, and harbours a series of unique and distinct ecosystems. Due to the upwelling of deep-water masses in the <span class="hlt">Antarctic</span> Divergence, there is high supply of natural CO2 as well as macronutrients, leading to the worldwide highest surface nutrient concentrations. Despite the ample macronutrients supply, phytoplankton concentration is generally low, limited either by low micronutrient (iron) availability, insufficient light due to deep wind-mixed layers or grazing by zooplankton, or by the combination of all, varying temporally and regionally.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21959188','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21959188"><span>Behavioural sensitivity of a key <span class="hlt">Southern</span> <span class="hlt">Ocean</span> species (<span class="hlt">Antarctic</span> krill, Euphausia superba) to p,p'-DDE exposure.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Poulsen, Anita H; Kawaguchi, So; King, Catherine K; King, Robert A; Bengtson Nash, Susan M</p> <p>2012-01-01</p> <p>Persistent organic pollutants (POPs) have been frequently measured throughout the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> food web for which little information is available to assess the potential risks of POP exposure. The current study evaluated the toxicological sensitivity of a key <span class="hlt">Southern</span> <span class="hlt">Ocean</span> species, <span class="hlt">Antarctic</span> krill, to aqueous exposure of p,p'-dichlorodiphenyl dichloroethylene (p,p'-DDE). Behavioural endpoints were used as indicators of sublethal toxicity. Immediate behavioural responses (partial immobility and tail flicking) most likely reflect neurotoxicity, while the p,p'-DDE body residue causing a median level of sublethal toxicity in <span class="hlt">Antarctic</span> krill following 96h exposure (IEC50(sublethal toxicity)=3.9±0.21mmol/kg lipid weight) is comparable to those known to cause sublethal narcosis in temperate aquatic species. Critical body residues (CBRs) were more reproducible across tests than effective seawater concentrations. These findings support the concept of the CBR approach, that effective tissue residues are comparable across species and geographical ranges despite differences in environmental factors. Copyright © 2011 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017DSRII.140..171A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017DSRII.140..171A"><span>Winter habitat predictions of a key <span class="hlt">Southern</span> <span class="hlt">Ocean</span> predator, the <span class="hlt">Antarctic</span> fur seal (Arctocephalus gazella)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arthur, Benjamin; Hindell, Mark; Bester, Marthan; De Bruyn, P. J. Nico; Trathan, Phil; Goebel, Michael; Lea, Mary-Anne</p> <p>2017-06-01</p> <p>Quantification of the physical and biological environmental factors that influence the spatial distribution of higher trophic species is central to inform management and develop ecosystem models, particularly in light of <span class="hlt">ocean</span> changes. We used tracking data from 184 female <span class="hlt">Antarctic</span> fur seals (Arctocephalus gazella) to develop habitat models for three breeding colonies for the poorly studied <span class="hlt">Southern</span> <span class="hlt">Ocean</span> winter period. Models were used to identify and predict the broadly important winter foraging habitat and to elucidate the environmental factors influencing these areas. Model predictions closely matched observations and several core areas of foraging habitat were identified for each colony, with notable areas of inter-colony overlap suggesting shared productive foraging grounds. Seals displayed clear choice of foraging habitat, travelling through areas of presumably poorer quality to access habitats that likely offer an energetic advantage in terms of prey intake. The relationships between environmental predictors and foraging habitat varied between colonies, with the principal predictors being wind speed, sea surface temperature, chlorophyll a concentration, bathymetry and distance to the colony. The availability of core foraging areas was not consistent throughout the winter period. The habitat models developed in this study not only reveal the core foraging habitats of <span class="hlt">Antarctic</span> fur seals from multiple colonies, but can facilitate the hindcasting of historical foraging habitats as well as novel predictions of important habitat for other major colonies currently lacking information of the at-sea distribution of this major <span class="hlt">Southern</span> <span class="hlt">Ocean</span> consumer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23372011','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23372011"><span>Recent changes in the ventilation of the <span class="hlt">southern</span> <span class="hlt">oceans</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Waugh, Darryn W; Primeau, Francois; Devries, Tim; Holzer, Mark</p> <p>2013-02-01</p> <p>Surface westerly winds in the <span class="hlt">Southern</span> Hemisphere have intensified over the past few decades, primarily in response to the formation of the <span class="hlt">Antarctic</span> ozone hole, and there is intense debate on the impact of this on the <span class="hlt">ocean</span>'s circulation and uptake and redistribution of atmospheric gases. We used measurements of chlorofluorocarbon-12 (CFC-12) made in the <span class="hlt">southern</span> <span class="hlt">oceans</span> in the early 1990s and mid- to late 2000s to examine changes in <span class="hlt">ocean</span> ventilation. Our analysis of the CFC-12 data reveals a decrease in the age of subtropical subantarctic mode waters and an increase in the age of circumpolar deep waters, suggesting that the formation of the <span class="hlt">Antarctic</span> ozone hole has caused large-scale coherent changes in the ventilation of the <span class="hlt">southern</span> <span class="hlt">oceans</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6463077-antarctic-ice-dynamics-southern-ocean-surface-hydrology-during-last-glacial-maximum','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/6463077-antarctic-ice-dynamics-southern-ocean-surface-hydrology-during-last-glacial-maximum"><span><span class="hlt">Antarctic</span> ice dynamics and <span class="hlt">southern</span> <span class="hlt">ocean</span> surface hydrology during the last glacial maximum</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Labeyrie, L.D.; Burckle, L.; Labracherie, M.</p> <p>1985-01-01</p> <p>Eight high sedimentation rate cores located between 61/sup 0/S and 43/sup 0/S in the Atlantic and Indian sectors of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> have been studied in detail for foraminifera and diatom /sup 18/O//sup 16/O ratios, and changes in radiolarian and diatom specific abundance. Comparison of these different parameters permits a detailed description of the surface water hydrology during the last glacial maximum. The authors demonstrate that from 25 kyr BP to 15 kyr BP a large number of icebergs formed around the <span class="hlt">Antarctic</span> continent. Melting along the Polar Front decreased surface salinity by approximately 1.5 per thousand between 43/sup 0/Smore » and 50/sup 0/S. They propose that an increase of snow accumulation at the <span class="hlt">Antarctic</span> periphery and downdraw during maximum ice extension are primary causes for this major discharge of icebergs.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Natur.511..574G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Natur.511..574G"><span><span class="hlt">Antarctic</span> glaciation caused <span class="hlt">ocean</span> circulation changes at the Eocene-Oligocene transition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goldner, A.; Herold, N.; Huber, M.</p> <p>2014-07-01</p> <p>Two main hypotheses compete to explain global cooling and the abrupt growth of the <span class="hlt">Antarctic</span> ice sheet across the Eocene-Oligocene transition about 34 million years ago: thermal isolation of Antarctica due to <span class="hlt">southern</span> <span class="hlt">ocean</span> gateway opening, and declining atmospheric CO2 (refs 5, 6). Increases in <span class="hlt">ocean</span> thermal stratification and circulation in proxies across the Eocene-Oligocene transition have been interpreted as a unique signature of gateway opening, but at present both mechanisms remain possible. Here, using a coupled <span class="hlt">ocean</span>-atmosphere model, we show that the rise of <span class="hlt">Antarctic</span> glaciation, rather than altered palaeogeography, is best able to explain the observed oceanographic changes. We find that growth of the <span class="hlt">Antarctic</span> ice sheet caused enhanced northward transport of <span class="hlt">Antarctic</span> intermediate water and invigorated the formation of <span class="hlt">Antarctic</span> bottom water, fundamentally reorganizing <span class="hlt">ocean</span> circulation. Conversely, gateway openings had much less impact on <span class="hlt">ocean</span> thermal stratification and circulation. Our results support available evidence that CO2 drawdown--not gateway opening--caused <span class="hlt">Antarctic</span> ice sheet growth, and further show that these feedbacks in turn altered <span class="hlt">ocean</span> circulation. The precise timing and rate of glaciation, and thus its impacts on <span class="hlt">ocean</span> circulation, reflect the balance between potentially positive feedbacks (increases in sea ice extent and enhanced primary productivity) and negative feedbacks (stronger southward heat transport and localized high-latitude warming). The <span class="hlt">Antarctic</span> ice sheet had a complex, dynamic role in <span class="hlt">ocean</span> circulation and heat fluxes during its initiation, and these processes are likely to operate in the future.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25079555','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25079555"><span><span class="hlt">Antarctic</span> glaciation caused <span class="hlt">ocean</span> circulation changes at the Eocene-Oligocene transition.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Goldner, A; Herold, N; Huber, M</p> <p>2014-07-31</p> <p>Two main hypotheses compete to explain global cooling and the abrupt growth of the <span class="hlt">Antarctic</span> ice sheet across the Eocene-Oligocene transition about 34 million years ago: thermal isolation of Antarctica due to <span class="hlt">southern</span> <span class="hlt">ocean</span> gateway opening, and declining atmospheric CO2 (refs 5, 6). Increases in <span class="hlt">ocean</span> thermal stratification and circulation in proxies across the Eocene-Oligocene transition have been interpreted as a unique signature of gateway opening, but at present both mechanisms remain possible. Here, using a coupled <span class="hlt">ocean</span>-atmosphere model, we show that the rise of <span class="hlt">Antarctic</span> glaciation, rather than altered palaeogeography, is best able to explain the observed oceanographic changes. We find that growth of the <span class="hlt">Antarctic</span> ice sheet caused enhanced northward transport of <span class="hlt">Antarctic</span> intermediate water and invigorated the formation of <span class="hlt">Antarctic</span> bottom water, fundamentally reorganizing <span class="hlt">ocean</span> circulation. Conversely, gateway openings had much less impact on <span class="hlt">ocean</span> thermal stratification and circulation. Our results support available evidence that CO2 drawdown--not gateway opening--caused <span class="hlt">Antarctic</span> ice sheet growth, and further show that these feedbacks in turn altered <span class="hlt">ocean</span> circulation. The precise timing and rate of glaciation, and thus its impacts on <span class="hlt">ocean</span> circulation, reflect the balance between potentially positive feedbacks (increases in sea ice extent and enhanced primary productivity) and negative feedbacks (stronger southward heat transport and localized high-latitude warming). The <span class="hlt">Antarctic</span> ice sheet had a complex, dynamic role in <span class="hlt">ocean</span> circulation and heat fluxes during its initiation, and these processes are likely to operate in the future.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017QSRv..155...50M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017QSRv..155...50M"><span>Ice core and climate reanalysis analogs to predict <span class="hlt">Antarctic</span> and <span class="hlt">Southern</span> Hemisphere climate changes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mayewski, P. A.; Carleton, A. M.; Birkel, S. D.; Dixon, D.; Kurbatov, A. V.; Korotkikh, E.; McConnell, J.; Curran, M.; Cole-Dai, J.; Jiang, S.; Plummer, C.; Vance, T.; Maasch, K. A.; Sneed, S. B.; Handley, M.</p> <p>2017-01-01</p> <p>A primary goal of the SCAR (Scientific Committee for <span class="hlt">Antarctic</span> Research) initiated AntClim21 (<span class="hlt">Antarctic</span> Climate in the 21st Century) Scientific Research Programme is to develop analogs for understanding past, present and future climates for the <span class="hlt">Antarctic</span> and <span class="hlt">Southern</span> Hemisphere. In this contribution to AntClim21 we provide a framework for achieving this goal that includes: a description of basic climate parameters; comparison of existing climate reanalyses; and ice core sodium records as proxies for the frequencies of marine air mass intrusion spanning the past ∼2000 years. The resulting analog examples include: natural variability, a continuation of the current trend in <span class="hlt">Antarctic</span> and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> climate characterized by some regions of warming and some cooling at the surface of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, <span class="hlt">Antarctic</span> ozone healing, a generally warming climate and separate increases in the meridional and zonal winds. We emphasize changes in atmospheric circulation because the atmosphere rapidly transports heat, moisture, momentum, and pollutants, throughout the middle to high latitudes. In addition, atmospheric circulation interacts with temporal variations (synoptic to monthly scales, inter-annual, decadal, etc.) of sea ice extent and concentration. We also investigate associations between <span class="hlt">Antarctic</span> atmospheric circulation features, notably the Amundsen Sea Low (ASL), and primary climate teleconnections including the SAM (<span class="hlt">Southern</span> Annular Mode), ENSO (El Nîno <span class="hlt">Southern</span> Oscillation), the Pacific Decadal Oscillation (PDO), the AMO (Atlantic Multidecadal Oscillation), and solar irradiance variations.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li class="active"><span>2</span></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_2 --> <div id="page_3" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li class="active"><span>3</span></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="41"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16791191','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16791191"><span>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> biogeochemical divide.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Marinov, I; Gnanadesikan, A; Toggweiler, J R; Sarmiento, J L</p> <p>2006-06-22</p> <p>Modelling studies have demonstrated that the nutrient and carbon cycles in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> play a central role in setting the air-sea balance of CO(2) and global biological production. Box model studies first pointed out that an increase in nutrient utilization in the high latitudes results in a strong decrease in the atmospheric carbon dioxide partial pressure (pCO2). This early research led to two important ideas: high latitude regions are more important in determining atmospheric pCO2 than low latitudes, despite their much smaller area, and nutrient utilization and atmospheric pCO2 are tightly linked. Subsequent general circulation model simulations show that the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is the most important high latitude region in controlling pre-industrial atmospheric CO(2) because it serves as a lid to a larger volume of the deep <span class="hlt">ocean</span>. Other studies point out the crucial role of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in the uptake and storage of anthropogenic carbon dioxide and in controlling global biological production. Here we probe the system to determine whether certain regions of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> are more critical than others for air-sea CO(2) balance and the biological export production, by increasing surface nutrient drawdown in an <span class="hlt">ocean</span> general circulation model. We demonstrate that atmospheric CO(2) and global biological export production are controlled by different regions of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. The air-sea balance of carbon dioxide is controlled mainly by the biological pump and circulation in the <span class="hlt">Antarctic</span> deep-water formation region, whereas global export production is controlled mainly by the biological pump and circulation in the Subantarctic intermediate and mode water formation region. The existence of this biogeochemical divide separating the <span class="hlt">Antarctic</span> from the Subantarctic suggests that it may be possible for climate change or human intervention to modify one of these without greatly altering the other.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1917509C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1917509C"><span>Dominant covarying climate signals in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and <span class="hlt">Antarctic</span> Sea Ice influence during last three decades</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cerrone, Dario; Fusco, Giannetta; Simmonds, Ian; Aulicino, Giuseppe; Budillon, Giorgio</p> <p>2017-04-01</p> <p>A composite dataset (comprising geopotential height, sea surface temperature, zonal and meridional surface winds, precipitation, cloud cover, surface air temperature, latent plus sensible heat fluxes , and sea ice concentration) has been investigated with the aim of revealing the dominant timescales of variability from 1982 to 2013. Three covarying climate signals associated with variations in the sea ice distribution around Antarctica have been detected through the application of the Multiple-Taper Method with Singular Value Decomposition (MTM-SVD). Features of the established patterns of variation over the <span class="hlt">Southern</span> Hemisphere (SH) extratropics have been identified in each of these three climate signals in the form of coupled or individual oscillations. The climate patterns considered here are the <span class="hlt">Southern</span> Annular Mode (SAM), the Pacific-South America (PSA) teleconnection, the Semi-Annual Oscillation (SAO) and Zonal Wavenumber-3 (ZW3) mode. It is shown that most of the sea ice temporal variance is concentrated at the quasi-triennial scale resulting from the constructive superposition of the PSA and ZW3 patterns. In addition the combination of the SAM and SAO patterns is found to promote the interannual sea ice variations underlying a general change in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> atmospheric and <span class="hlt">oceanic</span> circulations. These two modes of variability are also found consistent with the occurrence of the SAM+/PSA- or SAM-/PSA+ combinations, which could have favored the cooling of the sub-<span class="hlt">Antarctic</span> and important changes in the <span class="hlt">Antarctic</span> sea ice distribution since 2000.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20584566','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20584566"><span>Perfluorinated compounds in the <span class="hlt">Antarctic</span> region: <span class="hlt">ocean</span> circulation provides prolonged protection from distant sources.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bengtson Nash, Susan; Rintoul, Stephen R; Kawaguchi, So; Staniland, Iain; van den Hoff, John; Tierney, Megan; Bossi, Rossana</p> <p>2010-09-01</p> <p>In order to investigate the extent to which Perfluorinated Contaminants (PFCs) have permeated the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> food web to date, a range of <span class="hlt">Antarctic</span>, sub-<span class="hlt">Antarctic</span> and <span class="hlt">Antarctic</span>-migratory biota were analysed for key ionic PFCs. Based upon the geographical distribution pattern and ecology of biota with detectable vs. non-detectable PFC burdens, an evaluation of the potential contributory roles of alternative system input pathways is made. Our analytical findings, together with previous reports, reveal only the occasional occurrence of PFCs in migratory biota and vertebrate predators with foraging ranges extending into or north of the <span class="hlt">Antarctic</span> Circumpolar Current (ACC). Geographical contamination patterns observed correspond most strongly with those expected from delivery via hydrospheric transport as governed by the unique oceanographic features of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. We suggest that hydrospheric transport will form a slow, but primary, input pathway of PFCs to the <span class="hlt">Antarctic</span> region. Copyright (c) 2010 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A53L..01B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A53L..01B"><span>Is it Becoming Warmer and Wetter in the <span class="hlt">Antarctic</span>? A Look at Evaporation from the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Boisvert, L.; Shie, C. L.</p> <p>2017-12-01</p> <p>The process of evaporation provides water vapor from the surface to the atmosphere, where it becomes the most radiatively important and abundant greenhouse gas altering the Earth's energy balance. Hence evaporation plays an essential role in a wide variety of atmospheric and <span class="hlt">oceanic</span> problems. Evaporation is a key component of both the water cycle and the surface energy balance and thus information on this process is crucial in understanding the interaction between the atmosphere and <span class="hlt">oceans</span>, global energy and water cycle variability, and in improving model simulations of climate variations. Although evaporation is an important term in climate model physics it is often poorly captured because surface in-situ measurements of evaporation are scarce in both space and time, especially over the Polar Regions, because evaporation is not easily measured directly. The <span class="hlt">Antarctic</span> sea ice acts as a barrier between the <span class="hlt">ocean</span> and atmosphere inhibiting the exchange of heat, momentum, and moisture. However, variations in the sea ice cover could lead to changes in the amount of moisture supplied to the atmosphere. Variations in the sea ice coverage could potentially allow for larger vertical moisture fluxes that affect surface energy budgets, larger occurrences of low-level clouds, and higher near-surface humidity and temperatures. These changes to the local atmosphere could then potentially impact nearby atmospheric conditions over the <span class="hlt">Antarctic</span> ice sheet, which could be particularly important in regions that are susceptible to collapse like the West <span class="hlt">Antarctic</span> Ice Sheet. NASA's Atmospheric Infrared Sounder (AIRS) has been used in multiple studies to study sea-ice atmosphere interactions in the Arctic <span class="hlt">Ocean</span> with great success, specifically in evaporation (i.e. the moisture flux). However, little research has been done looking at the moisture flux from the <span class="hlt">Antarctic</span> sea ice pack and nearby areas of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. This work will use data from AIRS and the moisture flux scheme</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930005782&hterms=McDougall&qs=N%3D0%26Ntk%3DAuthor-Name%26Ntx%3Dmode%2Bmatchall%26Ntt%3DMcDougall','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930005782&hterms=McDougall&qs=N%3D0%26Ntk%3DAuthor-Name%26Ntx%3Dmode%2Bmatchall%26Ntt%3DMcDougall"><span><span class="hlt">Ocean</span> transport and variability studies of the South Pacific, <span class="hlt">Southern</span>, and Indian <span class="hlt">Oceans</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Church, John A.; Cresswell, G. R.; Nilsson, C. S.; Mcdougall, T. J.; Coleman, R.; Rizos, C.; Penrose, J.; Hunter, J. R.; Lynch, M. J.</p> <p>1991-01-01</p> <p>The objectives of this study are to analyze <span class="hlt">ocean</span> dynamics in the western South Pacific and the adjacent <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and the eastern Indian <span class="hlt">Ocean</span>. Specifically, our objectives for these three regions are, for the South Pacific <span class="hlt">Ocean</span>: (1) To estimate the volume transport of the east Australian Current (EAC) along the Australian coast and in the Tasman Front, and to estimate the time variability (on seasonal and interannual time scales) of this transport. (2) To contribute to estimating the meridional heat and freshwater fluxes (and their variability) at about 30 deg S. Good estimates of the transport in the western boundary current are essential for accurate estimates of these fluxes. (3) To determine how the EAC transport (and its extension, the Tasman Front and the East Auckland Current) closes the subtropical gyre of the South Pacific and to better determine the structure at the confluence of this current and the <span class="hlt">Antarctic</span> Circumpolar Current. (4) To examine the structure and time variability of the circulation in the western South Pacific and the adjacent <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, particularly at the Tasman Front. For the Indian <span class="hlt">Ocean</span>: (5) To study the seasonal interannual variations in the strength of the Leeuwin Current. (6) To monitor the Pacific-Indian <span class="hlt">Ocean</span> throughflow and the South Equatorial and the South Java Currents between northwest Australia and Indonesia. (7) To study the processes that form the water of the permanent <span class="hlt">oceanic</span> thermocline and, in particular, the way in which new thermocline water enters the permanent thermocline in late winter and early spring as the mixed layer restratifies. For the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>: (8) To study the mesoscale and meridional structure of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> between 150 deg E and 170 deg E; in particular, to describe the <span class="hlt">Antarctic</span> frontal system south of Tasmania and determine its interannual variability; to estimate the exchanges of heat, salt, and other properties between the Indian and Pacific <span class="hlt">Oceans</span>; and to investigate the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17..166S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17..166S"><span>Seabird guano enhances phytoplankton production in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shatova, Olga; Wing, Stephen; Hoffmann, Linn; Jack, Lucy; Gault-Ringold, Melanie</p> <p>2015-04-01</p> <p>Great congregations of seabirds in sub-<span class="hlt">Antarctic</span> and <span class="hlt">Antarctic</span> coastal areas result in delivery of nutrient-rich guano to marine ecosystems that potentially enhances productivity and supports biodiversity in the region. Guano-derived bio-available micronutrients and macronutrients might be utilized by marine phytoplankton for photosynthetic production, however, mechanisms and significance of guano fertilization in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> are largely understudied. Over austral summers of 2012 and 2013 we performed a series of guano-enrichment phytoplankton incubation experiments with water samples collected from three different water masses in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>: <span class="hlt">Antarctic</span> waters of the Ross sea and sub-<span class="hlt">Antarctic</span> waters offshore the Otago Peninsula, both showing iron limitation of phytoplankton productivity in summer, and in the subtropical frontal zone offshore from the Snares Islands, which is generally micronutrient-repleted. Samples were enriched with known concentrations of guano-derived nutrients. Phytoplankton biomass increased significantly in guano-treated samples during all three incubation experiments (7-10 fold increase), while remained low in control samples. This response indicates that seabird guano provides nutrients that limit primary production in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and that these nutrients are readily taken up by phytoplankton. Guano additions were compared to Fe and Macronutrient treatments (both added in quantities similar to those in the guano treatment). Phytoplankton biomass increased significantly in response to the Macronutrient treatment in the subtropical frontal zone, however, the response had a smaller magnitude compared to the guano treatment (2.8 µgL-1 vs 5.2 µgL-1) ; there was no significant effect of Fe on phytoplankton growth. This suggests the potential importance of synergistic effects of nutrients in guano. Incubation with sub-<span class="hlt">Antarctic</span> waters showed that Fe and Macronutrients might be equally important for enhancement of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26674704','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26674704"><span>Wide range of metallic and organic contaminants in various tissues of the <span class="hlt">Antarctic</span> prion, a planktonophagous seabird from the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fromant, Aymeric; Carravieri, Alice; Bustamante, Paco; Labadie, Pierre; Budzinski, Hélène; Peluhet, Laurent; Churlaud, Carine; Chastel, Olivier; Cherel, Yves</p> <p>2016-02-15</p> <p>Trace elements (n=14) and persistent organic pollutants (POPs, n=30) were measured in blood, liver, kidney, muscle and feathers of 10 <span class="hlt">Antarctic</span> prions (Pachyptila desolata) from Kerguelen Islands, <span class="hlt">southern</span> Indian <span class="hlt">Ocean</span>, in order to assess their concentrations, tissue distribution, and inter-tissue and inter-contaminant relationships. Liver, kidney and feathers presented the highest burdens of arsenic, cadmium and mercury, respectively. Concentrations of cadmium, copper, iron, and zinc correlated in liver and muscle, suggesting that uptake and pathways of metabolism and storage were similar for these elements. The major POPs were 4,4'-DDE, mirex, PCB-153 and PCB-138. The concentrations and tissue distribution patterns of environmental contaminants were overall in accordance with previous results in other seabirds. Conversely, some <span class="hlt">Antarctic</span> prions showed surprisingly high concentrations of BDE-209. This compound has been rarely observed in seabirds before, and its presence in <span class="hlt">Antarctic</span> prions could be due to the species feeding habits or to the ingestion of plastic debris. Overall, the study shows that relatively lower trophic level seabirds (zooplankton-eaters) breeding in the remote <span class="hlt">southern</span> Indian <span class="hlt">Ocean</span> are exposed to a wide range of environmental contaminants, in particular cadmium, selenium and some emerging-POPs, which merits further toxicological investigations. Copyright © 2015 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GeoRL..45.2413S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GeoRL..45.2413S"><span>Does <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Surface Forcing Shape the Global <span class="hlt">Ocean</span> Overturning Circulation?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sun, Shantong; Eisenman, Ian; Stewart, Andrew L.</p> <p>2018-03-01</p> <p>Paleoclimate proxy data suggest that the Atlantic Meridional Overturning Circulation (AMOC) was shallower at the Last Glacial Maximum (LGM) than its preindustrial (PI) depth. Previous studies have suggested that this shoaling necessarily accompanies <span class="hlt">Antarctic</span> sea ice expansion at the LGM. Here the influence of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> surface forcing on the AMOC depth is investigated using <span class="hlt">ocean</span>-only simulations from a state-of-the-art climate model with surface forcing specified from the output of previous coupled PI and LGM simulations. In contrast to previous expectations, we find that applying LGM surface forcing in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and PI surface forcing elsewhere causes the AMOC to shoal only about half as much as when LGM surface forcing is applied globally. We show that this occurs because diapycnal mixing renders the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> overturning circulation more diabatic than previously assumed, which diminishes the influence of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> surface buoyancy forcing on the depth of the AMOC.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMPP53D..06P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMPP53D..06P"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> Deep-Convection as a Driver of Centennial-to-Millennial-Scale Climate Variability at <span class="hlt">Southern</span> High Latitudes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pedro, J. B.; Martin, T.; Steig, E. J.; Jochum, M.; Park, W.; Rasmussen, S.</p> <p>2015-12-01</p> <p><span class="hlt">Antarctic</span> Isotope Maxima (AIM) are centennial-to-millennial scale warming events observed in <span class="hlt">Antarctic</span> ice core records from the last glacial period and deglaciation. Mounting evidence links AIM events to parallel variations in atmospheric CO2, <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (SO) sea surface temperatures and <span class="hlt">Antarctic</span> Bottom Water production. According to the prevailing view, AIM events are forced from the North Atlantic by melt-water discharge from ice sheets suppressing the production of North Atlantic Deep Water and associated northward heat transport in the Atlantic. However observations and model studies increasingly suggest that melt-water fluxes have the wrong timing to be invoked as such a trigger. Here, drawing on results form the Kiel Climate Model, we present an alternative hypothesis in which AIM events are forced via internal oscillations in SO deep-convection. The quasi-periodic timescale of deep-convection events is set by heat (buoyancy) accumulation at SO intermediate depths and stochastic variability in sea ice conditions and freshening at the surface. Massive heat release from the SO convective zone drives <span class="hlt">Antarctic</span> and large-scale <span class="hlt">southern</span> hemisphere warming via a two-stage process involving changes in the location of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> fronts, in the strength and intensity of the Westerlies and in meridional <span class="hlt">ocean</span> and atmospheric heat flux anomalies. The potential for AIM events to be driven by internal <span class="hlt">Southern</span> <span class="hlt">Ocean</span> processes and the identification of time-lags internal to the <span class="hlt">southern</span> high latitudes challenges conventional views on the North Atlantic as the pacemaker of millennial-scale climate variability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JESS..126...70K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JESS..126...70K"><span><span class="hlt">Ocean</span> sea-ice modelling in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> around Indian <span class="hlt">Antarctic</span> stations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kumar, Anurag; Dwivedi, Suneet; Rajak, D. Ram</p> <p>2017-07-01</p> <p>An eddy-resolving coupled <span class="hlt">ocean</span> sea-ice modelling is carried out in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> region (9°-78°E; 51°-71°S) using the MITgcm. The model domain incorporates the Indian <span class="hlt">Antarctic</span> stations, Maitri (11.7{°}E; 70.7{°}S) and Bharati (76.1{°}E; 69.4{°}S). The realistic simulation of the surface variables, namely, sea surface temperature (SST), sea surface salinity (SSS), surface currents, sea ice concentration (SIC) and sea ice thickness (SIT) is presented for the period of 1997-2012. The horizontal resolution of the model varies between 6 and 10 km. The highest vertical resolution of 5 m is taken near the surface, which gradually increases with increasing depths. The seasonal variability of the SST, SSS, SIC and currents is compared with the available observations in the region of study. It is found that the SIC of the model domain is increasing at a rate of 0.09% per month (nearly 1% per year), whereas, the SIC near Maitri and Bharati regions is increasing at a rate of 0.14 and 0.03% per month, respectively. The variability of the drift of the sea-ice is also estimated over the period of simulation. It is also found that the sea ice volume of the region increases at the rate of 0.0004 km3 per month (nearly 0.005 km3 per year). Further, it is revealed that the accumulation of sea ice around Bharati station is more as compared to Maitri station.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.8790T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.8790T"><span>Particulate export vs lateral advection in the <span class="hlt">Antarctic</span> Polar Front (<span class="hlt">Southern</span> Pacific <span class="hlt">Ocean</span>)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tesi, T.; Langone, L.; Ravaioli, M.; Capotondi, L.; Giglio, F.</p> <p>2012-04-01</p> <p>The overarching goal of our study was to describe and quantify the influence of lateral advection relative to the vertical export in the <span class="hlt">Antarctic</span> Polar Front (<span class="hlt">Southern</span> Pacific <span class="hlt">Ocean</span>). In areas where lateral advection of particulate material is significant, budgets of bioactive elements can be inaccurate if fluxes through the water column and to the seabed are exclusively interpreted as passive sinking of particles. However, detailed information on the influence of lateral advection in the water column in the <span class="hlt">southern</span> <span class="hlt">ocean</span> is lacking. With this in mind, our study focused between the twilight zone (i.e. mesopelagic) and the benthic nepheloid layer to understand the relative importance of lateral flux with increasing water depth. Measurements were performed south of the <span class="hlt">Antarctic</span> Polar Front for 1 year (January 10th 1999-January 3rd 2000) at 900, 1300, 2400, and 3700 m from the sea surface. The study was carried out using a 3.5 km long mooring line instrumented with sediment traps, current meters and sensors of temperature and conductivity. Sediment trap samples were characterized via several parameters including total mass flux, elemental composition (organic carbon, total nitrogen, biogenic silica, and calcium carbonate), concentration of metals (aluminum, iron, barium, and manganese), 210Pb activity, and foraminifera taxonomy. High fluxes of biogenic particles were observed in both summer 1999 and 2000 as a result of seasonal algal blooms associated with sea ice retreat and water column stratification. During no-productive periods, several high energy events occurred and resulted in advecting resuspended biogenic particles from flat-topped summits of the Pacific <span class="hlt">Antarctic</span> Ridge. Whereas the distance between seabed and uppermost sediment traps was sufficient to avoid lateral advection processes, resuspension was significant in the lowermost sediment traps accounting for ~60 and ~90% of the material caught at 2400 and 3700 m, respectively. Samples collected during</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.C12B..08T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.C12B..08T"><span>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span>'s role in <span class="hlt">ocean</span> circulation and climate transients</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thompson, A. F.; Stewart, A.; Hines, S.; Adkins, J. F.</p> <p>2017-12-01</p> <p>The ventilation of deep and intermediate density classes at the surface of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> impacts water mass modification and the air-sea exchange of heat and trace gases, which in turn influences the global overturning circulation and Earth's climate. Zonal variability occurs along the <span class="hlt">Antarctic</span> Circumpolar Current and the <span class="hlt">Antarctic</span> margins related to flow-topography interactions, variations in surface boundary conditions, and exchange with northern basins. Information about these zonal variations, and their impact on mass and tracer transport, are suppressed when the overturning is depicted as a two-dimensional (depth-latitude) streamfunction. Here we present an idealized, multi-basin, time-dependent circulation model that applies residual circulation theory in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and allows for zonal water mass transfer between different <span class="hlt">ocean</span> basins. This model efficiently determines the temporal evolution of the <span class="hlt">ocean</span>'s stratification, ventilation and overturning strength in response to perturbations in the external forcing. With this model we explore the dynamics that lead to transitions in the circulation structure between multiple, isolated cells and a three-dimensional, "figure-of-eight," circulation in which traditional upper and lower cells are interleaved. The transient model is also used to support a mechanistic explanation of the hemispheric asymmetry and phase lag associated with Dansgaard-Oeschger (DO) events during the last glacial period. In particular, the 200 year lag in <span class="hlt">southern</span> hemisphere temperatures, following a perturbation in North Atlantic deep water formation, depends critically on the migration of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> isopycnal outcropping in response to low-latitude stratification changes. Our results provide a self-consistent dynamical framework to explain various <span class="hlt">ocean</span> overturning transitions that have occurred over the Earth's last 100,000 years, and motivate an exploration of these mechanisms in more sophisticated climate models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20010020924&hterms=Russell&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26Nf%3DPublication-Date%257CBTWN%2B20000101%2B20001231%26N%3D0%26No%3D30%26Ntt%3DRussell','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20010020924&hterms=Russell&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26Nf%3DPublication-Date%257CBTWN%2B20000101%2B20001231%26N%3D0%26No%3D30%26Ntt%3DRussell"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> Response to NADW Changes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rind, David; Schmidt, G.; Russell, G.; deMenocal, P.; Hansen, James E. (Technical Monitor)</p> <p>2000-01-01</p> <p>The possibility of North Atlantic Deep Water (NADW) changes in both past and future climates has raised the issue of how the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> would respond. Recent experiments with the GISS coupled atmosphere-<span class="hlt">ocean</span> model have shown that a "bipolar see-saw" between NADW production and <span class="hlt">Antarctic</span> Bottom Water (AABW) production in the Weddell Sea can occur in conjunction with freshening of the North Atlantic. However, this effect operates not through a slow <span class="hlt">ocean</span> response but via a rapid atmospheric mechanism. As NADW reduces, colder temperatures in the North Atlantic, and Northern Hemisphere in general, are associated with higher surface pressure (increased atmospheric mass). Reduced mass in the <span class="hlt">Southern</span> Hemisphere occurs in response, with lower pressure over the South Pole (an EOF #1 effect, the "high phase" of the <span class="hlt">Antarctic</span> Oscillation).The lower pressure is associated with stronger west winds that generate an intensified <span class="hlt">Antarctic</span> Circumpolar Current (ACC), which leads to longitudinal heat divergence in the South Atlantic (and heat convergence in the <span class="hlt">Southern</span> Indian <span class="hlt">Ocean</span>). Colder temperatures in the Weddell Sea region lead to sea ice growth, increased salinity and surface water density, and greater Weddell Sea Bottom Water production. Increased poleward transport of heat occurs in the South Atlantic in conjunction with increased bottom water production, but its convergence at high latitudes is not sufficient to offset the longitudinal heat divergence due to the intensified ACC. The colder temperatures at high latitudes in the South Atlantic increase the latitudinal temperature gradient, baroclinic instability, eddy energy and eddy poleward transport of momentum, helping to maintain the lower pressure over the pole in an interactive manner. The heat flux convergence in the Indian <span class="hlt">Ocean</span> provides a warming tendency in that region, and overall global production of AABW remains unchanged. These results have implications for the interpretation of the ice core records of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/7005299-southern-rim-pacific-ocean-basin-southern-andes-southern-alps','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/7005299-southern-rim-pacific-ocean-basin-southern-andes-southern-alps"><span><span class="hlt">Southern</span> rim of Pacific <span class="hlt">Ocean</span> basin: <span class="hlt">southern</span> Andes to <span class="hlt">southern</span> Alps</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Dalziel, I.W.D.; Garrett, S.W.; Grunow, A.M.</p> <p>1986-07-01</p> <p>Between the <span class="hlt">southern</span> Andes of Tierra del Fuego and the <span class="hlt">southern</span> Alps of New Zealand lies the least accessible and geologically least explored part of the Pacific <span class="hlt">Ocean</span> basin. A joint United Kingdom-United States project was initiated in 1983 to elucidate the geologic history and structure of the Pacific margin of Antarctica from the <span class="hlt">Antarctic</span> Peninsula to Pine Island Bay at approximately lone. 105/sup 0/W. The first season (1983-1984) of this West <span class="hlt">Antarctic</span> Tectonics Project was spent in the Ellsworth-Whitmore crustal block, and the second (1984-1985) in the Thurston Island crustal block. The project involves structural and general field geology,more » petrology, geochemistry, paleomagnetism, and airborne geophysics (magnetics and radar ice echo sounding). A final geologic season will be spent in the Pensacola Mountains of the Transantarctic Range in 1987-1988.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28769035','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28769035"><span>Spiraling pathways of global deep waters to the surface of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tamsitt, Veronica; Drake, Henri F; Morrison, Adele K; Talley, Lynne D; Dufour, Carolina O; Gray, Alison R; Griffies, Stephen M; Mazloff, Matthew R; Sarmiento, Jorge L; Wang, Jinbo; Weijer, Wilbert</p> <p>2017-08-02</p> <p>Upwelling of global deep waters to the sea surface in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> closes the global overturning circulation and is fundamentally important for <span class="hlt">oceanic</span> uptake of carbon and heat, nutrient resupply for sustaining <span class="hlt">oceanic</span> biological production, and the melt rate of ice shelves. However, the exact pathways and role of topography in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> upwelling remain largely unknown. Here we show detailed upwelling pathways in three dimensions, using hydrographic observations and particle tracking in high-resolution models. The analysis reveals that the northern-sourced deep waters enter the <span class="hlt">Antarctic</span> Circumpolar Current via southward flow along the boundaries of the three <span class="hlt">ocean</span> basins, before spiraling southeastward and upward through the <span class="hlt">Antarctic</span> Circumpolar Current. Upwelling is greatly enhanced at five major topographic features, associated with vigorous mesoscale eddy activity. Deep water reaches the upper <span class="hlt">ocean</span> predominantly south of the <span class="hlt">Antarctic</span> Circumpolar Current, with a spatially nonuniform distribution. The timescale for half of the deep water to upwell from 30° S to the mixed layer is ~60-90 years.Deep waters of the Atlantic, Pacific and Indian <span class="hlt">Oceans</span> upwell in the <span class="hlt">Southern</span> Oceanbut the exact pathways are not fully characterized. Here the authors present a three dimensional view showing a spiralling southward path, with enhanced upwelling by eddy-transport at topographic hotspots.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1918335T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1918335T"><span>Rapid <span class="hlt">ocean</span>-atmosphere response to <span class="hlt">Southern</span> <span class="hlt">Ocean</span> freshening during the last glacial period</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Turney, Christian; Jones, Richard; Phipps, Steven; Thomas, Zoë; Hogg, Alan; Kershaw, Peter; Fogwill, Christopher; Palmer, Jonathan; Bronk Ramsey, Christopher; Adolphi, Florian; Muscheler, Raimund; Hughen, Konrad; Staff, Richard; Grosvenor, Mark; Golledge, Nicholas; Rasmussen, Sune; Hutchinson, David; Haberle, Simon; Lorrey, Andrew; Boswijk, Gretel</p> <p>2017-04-01</p> <p>Contrasting Greenland and <span class="hlt">Antarctic</span> temperature trends during the late last glacial period (60,000 to 11,703 years ago) are thought to be driven by imbalances in the rate of formation of North Atlantic and <span class="hlt">Antarctic</span> Deep Water (the 'bipolar seesaw'), with cooling in the north leading the onset of warming in the south. Some events, however, appear to have occurred independently of changes in deep water formation but still have a <span class="hlt">southern</span> expression, implying that an alternative mechanism may have driven some global climatic changes during the glacial. Testing these competing hypotheses is challenging given the relatively large uncertainties associated with correlating terrestrial, marine and ice core records of abrupt change. Here we exploit a bidecadally-resolved 14C calibration dataset obtained from New Zealand kauri (Agathis australis) to undertake high-precision alignment of key climate datasets spanning 28,400 to 30,400 years ago. We observe no divergence between terrestrial and marine 14C datasets implying limited impact of freshwater hosing on the Atlantic Meridional Overturning Circulation (AMOC). However, an ice-rafted debris event (SA2) in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> waters appears to be associated with dramatic synchronous warming over the North Atlantic and contrasting precipitation patterns across the low latitudes. Using a fully coupled climate system model we undertook an ensemble of transient meltwater simulations and find that a <span class="hlt">southern</span> salinity anomaly can trigger low-latitude temperature changes through barotropic and baroclinic <span class="hlt">oceanic</span> waves that are atmospherically propagated globally via a Rossby wave train, consistent with contemporary modelling studies. Our results suggest the <span class="hlt">Antarctic</span> ice sheets and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> dynamics may have contributed to some global climatic changes through rapid <span class="hlt">ocean</span>-atmospheric teleconnections, with implications for past (and future) change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017NatGe..10..840R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NatGe..10..840R"><span>Contribution of topographically generated submesoscale turbulence to <span class="hlt">Southern</span> <span class="hlt">Ocean</span> overturning</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ruan, Xiaozhou; Thompson, Andrew F.; Flexas, Mar M.; Sprintall, Janet</p> <p>2017-11-01</p> <p>The <span class="hlt">ocean</span>'s global overturning circulation regulates the transport and storage of heat, carbon and nutrients. Upwelling across the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>'s <span class="hlt">Antarctic</span> Circumpolar Current and into the mixed layer, coupled to water mass modification by surface buoyancy forcing, has been highlighted as a key process in the closure of the overturning circulation. Here, using twelve high-resolution hydrographic sections in <span class="hlt">southern</span> Drake Passage, collected with autonomous <span class="hlt">ocean</span> gliders, we show that Circumpolar Deep Water originating from the North Atlantic, known as Lower Circumpolar Deep Water, intersects sloping topography in narrow and strong boundary currents. Observations of strong lateral buoyancy gradients, enhanced bottom turbulence, thick bottom mixed layers and modified water masses are consistent with growing evidence that topographically generated submesoscale flows over continental slopes enhance near-bottom mixing, and that cross-density upwelling occurs preferentially over sloping topography. Interactions between narrow frontal currents and topography occur elsewhere along the path of the <span class="hlt">Antarctic</span> Circumpolar Current, which leads us to propose that such interactions contribute significantly to the closure of the overturning in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMPP43B1344H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMPP43B1344H"><span>Paleobathymetric grids of the Cenozoic <span class="hlt">Southern</span> <span class="hlt">Ocean</span> - Opening the door towards improved reconstructions of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>'s past</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hochmuth, K.; Gohl, K.; Leitchenkov, G. L.; Sauermilch, I.; Whittaker, J. M.; De Santis, L.; Olivo, E.; Uenzelmann-Neben, G.; Davy, B. W.</p> <p>2017-12-01</p> <p>Although the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> plays a fundamental role in the global climate and <span class="hlt">ocean</span> current system, paleo-<span class="hlt">ocean</span> circulation models of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> suffer from missing boundary conditions. A more accurate representation of the geometry of the seafloor and their dynamics over long time-scales are key for enabling more precise reconstructions of the development of the paleo-currents, the paleo-environment and the <span class="hlt">Antarctic</span> ice sheets. The accurate parameterisation of these models controls the meaning and implications of regional and global paleo-climate models. The dynamics of <span class="hlt">ocean</span> currents in proximity of the continental margins is also controlled by the development of the regional seafloor morphology of the conjugate continental shelves, slopes and rises. The reassessment of all available reflection seismic and borehole data from Antarctica as well as its conjugate margins of Australia, New Zealand, South Africa and South America, allows us to create paleobathymetric grids for various time slices during the Cenozoic. Those grids inform us about sediment distribution and volume as well a local sedimentation rates. The earliest targeted time slice of the Eocene/Oligocene Boundary marks a significant turning point towards an icehouse climate. From latest Eocene to earliest Oligocene the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> changes fundamentally from a post greenhouse to an icehouse environment with the establishment of a vast continental ice sheet on the <span class="hlt">Antarctic</span> continent. With the calculated sediment distribution maps, we can evaluate the dynamics of the sedimentary cover as well as the development of structural obstacles such as <span class="hlt">oceanic</span> plateaus and ridges. The ultimate aim of this project is - as a community based effort - to create paleobathymetric grids at various time slices such as the Mid-Miocene Climatic Optimum and the Pliocene/Pleistocene, and eventually mimic the time steps used within the modelling community. The observation of sediment distribution and local sediment</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSHE53B..07N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSHE53B..07N"><span>Meltwater Pathways and Iron Delivery to the <span class="hlt">Antarctic</span> Coastal <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Null, K. A.; Corbett, D. R.; Crenshaw, J.; Peterson, R. N.; Peterson, L.; Buck, C. S.; Lyons, W. B.</p> <p>2016-02-01</p> <p>Freshwater inputs to the <span class="hlt">Antarctic</span> coastal <span class="hlt">ocean</span> can occur through multiple pathways including calving, streams, and groundwater discharge. The impacts of submarine groundwater discharge on polar ecosystems are generally poorly understood and, until recently, had not been considered as an important physical process along the coast of the <span class="hlt">Antarctic</span> continent. Here, we present a study utilizing multiple tracers (radium, radon, and stable water isotopes) to quantify freshwater inputs and chemical constituent fluxes associated with multiple discharge pathways, including submarine groundwater discharge, along the Western <span class="hlt">Antarctic</span> Peninsula. Previous research has shown that primary production in iron-limited waters offshore of the <span class="hlt">Antarctic</span> Peninsula is fueled in part by continentally-derived sediments, and our work demonstrates that subglacial/submarine groundwater discharge (SSGD) to continental shelf waters in the region is also an important source of dissolved iron (6.4 Gg yr-1; dFe). For reference, this flux equates to approximately 25 times the iron flux from calving in the study area. SSGD also contributed a significantly higher macronutrient flux than calving, although calving contributed more than twice as much freshwater. Thus, SSGD is likely a much more important source of macronutrients and dFe to the nearshore coastal <span class="hlt">ocean</span> along the Western <span class="hlt">Antarctic</span> Peninsula, and potentially to the continental shelf and offshore waters of the entire continent than previously recognized. If we assume similar discharge rates along the entire <span class="hlt">Antarctic</span> coastline ( 45,000 km), the delivery of dFe via SSGD ( 216 Gg yr-1) is comparable to the other fluxes of Fe to the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> via dust, icebergs, and glacial runoff from the <span class="hlt">Antarctic</span> Ice Sheet, and should be considered in future geochemical budgets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/5064243-physical-oceanography-tracer-chemistry-southern-ocean','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/5064243-physical-oceanography-tracer-chemistry-southern-ocean"><span>Physical oceanography and tracer chemistry of the <span class="hlt">southern</span> <span class="hlt">ocean</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Not Available</p> <p></p> <p>This report considers technical and scientific developments and research questions in studies of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> since its predecessor, /open quotes/<span class="hlt">Southern</span> <span class="hlt">Ocean</span> Dynamics--A Strategy for Scientific Exploration 1973-1983/close quotes/ was published. The summary lists key research questions in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> oceanography. Chapter 1 describes how <span class="hlt">Southern</span> <span class="hlt">Ocean</span> research has evolved to provide the basis for timely research toward more directed objectives. Chapter 2 recommends four research programs, encompassing many of the specific recommendations that follow. Appendix A provides the scientific background and Reference/Bibliography list for this report for: on air-sea-ice interaction; the <span class="hlt">Antarctic</span> Circumpolar Current; water mass conversion; chemical tracermore » oceanography; and numerical modeling of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Appendix B describes the satellite-based observation systems expected to be active during the next decade. Appendix C is a list of relevant reports published during 1981-1987. 146 refs.« less</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li class="active"><span>3</span></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_3 --> <div id="page_4" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active"><span>4</span></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="61"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ESSD....9..461P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ESSD....9..461P"><span>Seabed images from <span class="hlt">Southern</span> <span class="hlt">Ocean</span> shelf regions off the northern <span class="hlt">Antarctic</span> Peninsula and in the southeastern Weddell Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Piepenburg, Dieter; Buschmann, Alexander; Driemel, Amelie; Grobe, Hannes; Gutt, Julian; Schumacher, Stefanie; Segelken-Voigt, Alexandra; Sieger, Rainer</p> <p>2017-07-01</p> <p>Recent advances in underwater imaging technology allow for the gathering of invaluable scientific information on seafloor ecosystems, such as direct in situ views of seabed habitats and quantitative data on the composition, diversity, abundance, and distribution of epibenthic fauna. The imaging approach has been extensively used within the research project DynAMo (Dynamics of <span class="hlt">Antarctic</span> Marine Shelf Ecosystems) at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research Bremerhaven (AWI), which aimed to comparatively assess the pace and quality of the dynamics of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> benthos. Within this framework, epibenthic spatial distribution patterns have been comparatively investigated in two regions in the Atlantic sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>: the shelf areas off the northern tip of the <span class="hlt">Antarctic</span> Peninsula, representing a region with above-average warming of surface waters and sea-ice reduction, and the shelves of the eastern Weddell Sea as an example of a stable high-<span class="hlt">Antarctic</span> marine environment that is not (yet) affected by climate change. The AWI <span class="hlt">Ocean</span> Floor Observation System (OFOS) was used to collect seabed imagery during two cruises of the German research vessel Polarstern, ANT-XXIX/3 (PS81) to the <span class="hlt">Antarctic</span> Peninsula from January to March 2013 and ANT-XXXI/2 (PS96) to the Weddell Sea from December 2015 to February 2016. Here, we report on the image and data collections gathered during these cruises. During PS81, OFOS was successfully deployed at a total of 31 stations at water depths between 29 and 784 m. At most stations, series of 500 to 530 pictures ( > 15 000 in total, each depicting a seabed area of approximately 3.45 m2 or 2.3 × 1.5 m) were taken along transects approximately 3.7 km in length. During PS96, OFOS was used at a total of 13 stations at water depths between 200 and 754 m, yielding series of 110 to 293 photos (2670 in total) along transects 0.9 to 2.6 km in length. All seabed images taken during the two cruises</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1910971T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1910971T"><span>Pathways of upwelling deep waters to the surface of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tamsitt, Veronica; Drake, Henri; Morrison, Adele; Talley, Lynne; Dufour, Carolina; Gray, Alison; Griffies, Stephen; Mazloff, Matthew; Sarmiento, Jorge; Wang, Jinbo; Weijer, Wilbert</p> <p>2017-04-01</p> <p>Upwelling of Atlantic, Indian and Pacific deep waters to the sea surface in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> closes the global overturning circulation and is fundamentally important for <span class="hlt">oceanic</span> uptake of anthropogenic carbon and heat, nutrient resupply for sustaining <span class="hlt">oceanic</span> biological production, and the melt rate of ice shelves. Here we go beyond the two-dimensional view of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> upwelling, to show detailed <span class="hlt">Southern</span> <span class="hlt">Ocean</span> upwelling pathways in three dimensions, using hydrographic observations and particle tracking in high-resolution <span class="hlt">ocean</span> and climate models. The northern deep waters enter the <span class="hlt">Antarctic</span> Circumpolar Current (ACC) via narrow southward currents along the boundaries of the three <span class="hlt">ocean</span> basins, before spiraling southeastward and upward through the ACC. Upwelling is greatly enhanced at five major topographic features, associated with vigorous mesoscale eddy activity. Deep water reaches the upper <span class="hlt">ocean</span> predominantly south of the <span class="hlt">southern</span> ACC boundary, with a spatially nonuniform distribution, regionalizing warm water supply to <span class="hlt">Antarctic</span> ice shelves and the delivery of nutrient and carbon-rich water to the sea surface. The timescale for half of the deep water to upwell from 30°S to the mixed layer is on the order of 60-90 years, which has important implications for the timescale for signals to propagate through the deep <span class="hlt">ocean</span>. In addition, we quantify the diabatic transformation along particle trajectories, to identify where diabatic processes are important along the upwelling pathways.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20713736','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20713736"><span>Accelerated warming of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and its impacts on the hydrological cycle and sea ice.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Jiping; Curry, Judith A</p> <p>2010-08-24</p> <p>The observed sea surface temperature in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> shows a substantial warming trend for the second half of the 20th century. Associated with the warming, there has been an enhanced atmospheric hydrological cycle in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> that results in an increase of the <span class="hlt">Antarctic</span> sea ice for the past three decades through the reduced upward <span class="hlt">ocean</span> heat transport and increased snowfall. The simulated sea surface temperature variability from two global coupled climate models for the second half of the 20th century is dominated by natural internal variability associated with the <span class="hlt">Antarctic</span> Oscillation, suggesting that the models' internal variability is too strong, leading to a response to anthropogenic forcing that is too weak. With increased loading of greenhouse gases in the atmosphere through the 21st century, the models show an accelerated warming in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, and indicate that anthropogenic forcing exceeds natural internal variability. The increased heating from below (<span class="hlt">ocean</span>) and above (atmosphere) and increased liquid precipitation associated with the enhanced hydrological cycle results in a projected decline of the <span class="hlt">Antarctic</span> sea ice.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008PrOce..78..193H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008PrOce..78..193H"><span>Pteropods in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ecosystems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hunt, B. P. V.; Pakhomov, E. A.; Hosie, G. W.; Siegel, V.; Ward, P.; Bernard, K.</p> <p>2008-09-01</p> <p>To date, little research has been carried out on pelagic gastropod molluscs (pteropods) in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ecosystems. However, recent predictions are that, due to acidification resulting from a business as usual approach to CO 2 emissions (IS92a), <span class="hlt">Southern</span> <span class="hlt">Ocean</span> surface waters may begin to become uninhabitable for aragonite shelled thecosome pteropods by 2050. To gain insight into the potential impact that this would have on <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ecosystems, we have here synthesized available data on pteropod distributions and densities, assessed current knowledge of pteropod ecology, and highlighted knowledge gaps and directions for future research on this zooplankton group. Six species of pteropod are typical of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> south of the Sub-Tropical Convergence, including the four Thecosomes Limacina helicina antarctica, Limacina retroversa australis, Clio pyramidata, and Clio piatkowskii, and two Gymnosomes Clione limacina antarctica and Spongiobranchaea australis. Limacina retroversa australis dominated pteropod densities north of the Polar Front (PF), averaging 60 ind m -3 (max = 800 ind m -3) and 11% of total zooplankton at the Prince Edward Islands. South of the PF L. helicina antarctica predominated, averaging 165 ind m -3 (max = 2681 ind m -3) and up to >35% of total zooplankton at South Georgia, and up to 1397 ind m -3 and 63% of total zooplankton in the Ross Sea. Combined pteropods contributed <5% to total zooplankton in the Lazarev Sea, but 15% (max = 93%) to macrozooplankton in the East <span class="hlt">Antarctic</span>. In addition to regional density distributions we have synthesized data on vertical distributions, seasonal cycles, and inter-annual density variation. Trophically, gymnosome are specialist predators on thecosomes, while thecosomes are considered predominantly herbivorous, capturing food with a mucous web. The ingestion rates of L. retroversa australis are in the upper range for sub-<span class="hlt">Antarctic</span> mesozooplankton (31.2-4196.9 ng pig ind -1 d -1), while those of L</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25455366','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25455366"><span>Low densities of drifting litter in the African sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ryan, Peter G; Musker, Seth; Rink, Ariella</p> <p>2014-12-15</p> <p>Only 52 litter items (>1cm diameter) were observed in 10,467 km of at-sea transects in the African sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Litter density north of the Subtropical Front (0.58 items km(-2)) was less than in the adjacent South Atlantic <span class="hlt">Ocean</span> (1-6 items km(-2)), but has increased compared to the mid-1980s. Litter density south of the Subtropical Front was an order of magnitude less than in temperate waters (0.032 items km(-2)). There was no difference in litter density between sub-<span class="hlt">Antarctic</span> and <span class="hlt">Antarctic</span> waters either side of the <span class="hlt">Antarctic</span> Polar Front. Most litter was made of plastic (96%). Fishery-related debris comprised a greater proportion of litter south of the Subtropical Front (33%) than in temperate waters (13%), where packaging dominated litter items (68%). The results confirm that the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is the least polluted <span class="hlt">ocean</span> in terms of drifting debris and suggest that most debris comes from local sources. Copyright © 2014 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.U51A..07S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.U51A..07S"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> biogeochemical control of glacial/interglacial carbon dioxide change</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sigman, D. M.</p> <p>2014-12-01</p> <p>In the effort to explain the lower atmospheric CO2 concentrations observed during ice ages, two of the first hypotheses involved redistributing dissolved inorganic carbon (DIC) within the <span class="hlt">ocean</span>. Broecker (1982) proposed a strengthening of the <span class="hlt">ocean</span>'s biological pump during ice ages, which increased the dissolved inorganic carbon gradient between the dark, voluminous <span class="hlt">ocean</span> interior and the surface <span class="hlt">ocean</span>'s sun-lit, wind-mixed layer. Boyle (1988) proposed a deepening in the <span class="hlt">ocean</span> interior's pool of DIC associated with organic carbon regeneration, with its concentration maximum shifting from intermediate to abyssal depths. While not irrefutable, evidence has arisen that these mechanisms can explain much of the ice age CO2 reduction and that both were activated by changes in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. In the <span class="hlt">Antarctic</span> Zone, reduced exchange of water between the surface and the underlying <span class="hlt">ocean</span> sequestered more DIC in the <span class="hlt">ocean</span> interior (the biological pump mechanism). Dust-borne iron fertilization of the Subantarctic surface lowered CO2 partly by the biological pump mechanism and partly by Boyle's carbon deepening. Each mechanism owes a part of its CO2 effect to a transient increase in seafloor calcium carbonate dissolution, which raised the ice age <span class="hlt">ocean</span>'s alkalinity, causing it to absorb more CO2. However, calcium carbonate cycling also sets limits on these mechanisms and their CO2 effects, such that the combination of <span class="hlt">Antarctic</span> and Subantarctic changes is needed to achieve the full (80-100 ppm) ice age CO2 decline. Data suggest that these changes began at different phases in the development of the last ice age, 110 and 70 ka, respectively, explaining a 40 ppm CO2 drop at each time. We lack a robust understanding of the potential causes for both the implied reduction in <span class="hlt">Antarctic</span> surface/deep exchange and the increase in Subantarctic dust supply during ice ages. Thus, even if the evidence for these <span class="hlt">Southern</span> <span class="hlt">Ocean</span> changes were to become incontrovertible, conceptual gaps stand</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMPP52A..01H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMPP52A..01H"><span>Westerly Winds and the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> CO2 Sink Since the Last Glacial-Interglacial Transition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hodgson, D. A.; Saunders, K. M.; Roberts, S. J.; Perren, B.; Butz, C.; Sime, L. C.; Davies, S. J.; Grosjean, M.</p> <p>2017-12-01</p> <p>The capacity of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> carbon sink is partly controlled by the <span class="hlt">Southern</span> Hemisphere westerly winds (SHW) and sea ice. These regulate the upwelling of dissolved carbon-rich deep water to <span class="hlt">Antarctic</span> surface waters, determine the surface area for air-sea gas exchange and therefore modulate the net uptake of atmospheric CO2. Some models have proposed that strengthened SHW will result in a weakening of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> CO2 sink. If these models are correct, then one would expect that reconstructions of changes in SHW intensity on centennial to millennial timescales would show clear links with <span class="hlt">Antarctic</span> ice core and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> marine geological records of atmospheric CO2, temperature and sea ice. Here, we present a 12,300 year reconstruction of past wind strength based on three independent proxies that track the changing inputs of sea salt aerosols and minerogenic particles into lake sediments on sub-<span class="hlt">Antarctic</span> Macquarie Island. The proxies are consistent in showing that periods of high wind intensity corresponded with the increase in CO2 across the late Last Glacial-Interglacial Transition and in the last 7,000 years, suggesting that the winds have contributed to the long term outgassing of CO2 from the <span class="hlt">ocean</span> during these periods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.5078S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.5078S"><span>Oceanographic changes in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and <span class="hlt">Antarctic</span> cryosphere dynamics during the Oligocene and Miocene: a view from offshore Wilkes Land</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sangiorgi, Francesca; Bijl, Peter K.; Hartman, Julian D.; Schouten, Stefan; Brinkhuis, Henk</p> <p>2016-04-01</p> <p>With the ongoing increase in atmospheric CO2 and global temperatures, a fundamental scientific and societal question arises concerning the stability of the <span class="hlt">Antarctic</span> cryosphere. Modern observational data indicate the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> has experienced significant warming, with <span class="hlt">oceanic</span> fronts being pushed several tenth of km closer to the continent. Moreover, basal melt of ice shelves from warming <span class="hlt">oceans</span> is causing accelerated grounding line retreat of the <span class="hlt">Antarctic</span> ice sheets and shelves. However, monitoring data are available for the last few decades only, which prevents the evaluation of long-term changes in ice mass balance. Studying intervals in Earth's past history, which represent the best possible analogues of (near) future conditions, becomes thus essential. The Oligocene and Miocene Epochs encompass periods with CO2 concentrations between today's and those expected for the (near) future. It has also become clear that ice-proximal oceanographic regime is a critical factor for the stability and mass balance of ice sheets. Integrated <span class="hlt">Ocean</span> Drilling Program (IODP) Expedition 318 offshore Wilkes Land (East Antarctica) Site U1356 satisfies both requirements of being ice-proximal and having a relative complete, stratigraphically well-resolved Oligocene-Miocene sequence (albeit with a possible 5-Myrs gap between Late Oligocene and Early Miocene). This allows for the first time studying oceanographic changes and cryosphere dynamics in the interval ~34-13 Myrs. Thus far, ice-proximal reconstructions were hindered by the paucity of suitable sedimentary archives around Antarctica and/or poor stratigraphic constraints. We reconstructed changes in surface oceanography and seawater temperatures by means of dinoflagellate cyst assemblages and TEX86 paleothermometry. The dinocyst data suggest (summer) sea-ice occurrence at Site U1356 only for the first 1.5 Ma following the onset of full <span class="hlt">Antarctic</span> glaciation and after the Mid-Miocene Climatic Optimum. In between, both dinocysts</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRC..123..613A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRC..123..613A"><span>Dynamic Topography and Sea Level Anomalies of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>: Variability and Teleconnections</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Armitage, Thomas W. K.; Kwok, Ron; Thompson, Andrew F.; Cunningham, Glenn</p> <p>2018-01-01</p> <p>This study combines sea surface height (SSH) estimates of the ice-covered <span class="hlt">Southern</span> <span class="hlt">Ocean</span> with conventional open-<span class="hlt">ocean</span> SSH estimates from CryoSat-2 to produce monthly composites of dynamic <span class="hlt">ocean</span> topography (DOT) and sea level anomaly (SLA) on a 50 km grid spanning 2011-2016. This data set reveals the full <span class="hlt">Southern</span> <span class="hlt">Ocean</span> SSH seasonal cycle for the first time; there is an antiphase relationship between sea level on the <span class="hlt">Antarctic</span> continental shelf and the deeper basins, with coastal SSH highest in autumn and lowest in spring. As a result of this pattern of seasonal SSH variability, the barotropic component of the <span class="hlt">Antarctic</span> Slope Current (ASC) has speeds that are regionally up to twice as fast in the autumn. Month-to-month circulation variability of the Ross and Weddell Gyres is strongly influenced by the local wind field, and is correlated with the local wind curl (Ross: -0.58; Weddell: -0.67). SSH variability is linked to both the <span class="hlt">Southern</span> Oscillation and the <span class="hlt">Southern</span> Annular Mode, dominant modes of <span class="hlt">southern</span> hemisphere climate variability. In particular, during the strong 2015-2016 El Niño, a sustained negative coastal SLA of up to -6 cm, implying a weakening of the ASC, was observed in the Pacific sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. The ability to examine sea level variability in the seasonally ice-covered regions of the <span class="hlt">Southern</span> Ocean—climatically important regions with an acute sparsity of data—makes this new merged sea level record of particular interest to the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> oceanography and glaciology communities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020081024','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020081024"><span>Spatial Patterns of Variability in <span class="hlt">Antarctic</span> Surface Temperature: Connections to the <span class="hlt">Southern</span> Hemisphere Annular Mode and the <span class="hlt">Southern</span> Oscillation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kwok, Ron; Comiso, Josefino C.; Koblinsky, Chester J. (Technical Monitor)</p> <p>2002-01-01</p> <p>The 17-year (1982-1998) trend in surface temperature shows a general cooling over the <span class="hlt">Antarctic</span> continent, warming of the sea ice zone, with moderate changes over the <span class="hlt">oceans</span>. Warming of the peripheral seas is associated with negative trends in the regional sea ice extent. Effects of the <span class="hlt">Southern</span> Hemisphere Annular Mode (SAM) and the extrapolar <span class="hlt">Southern</span> Oscillation (SO) on surface temperature are quantified through regression analysis. Positive polarities of the SAM are associated with cold anomalies over most of Antarctica, with the most notable exception of the <span class="hlt">Antarctic</span> Peninsula. Positive temperature anomalies and ice edge retreat in the Pacific sector are associated with El Nino episodes. Over the past two decades, the drift towards high polarity in the SAM and negative polarity in the SO indices couple to produce a spatial pattern with warmer temperatures in the <span class="hlt">Antarctic</span> Peninsula and peripheral seas, and cooler temperatures over much of East Antarctica.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GMD....11.1257N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GMD....11.1257N"><span>Intercomparison of <span class="hlt">Antarctic</span> ice-shelf, <span class="hlt">ocean</span>, and sea-ice interactions simulated by MetROMS-iceshelf and FESOM 1.4</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Naughten, Kaitlin A.; Meissner, Katrin J.; Galton-Fenzi, Benjamin K.; England, Matthew H.; Timmermann, Ralph; Hellmer, Hartmut H.; Hattermann, Tore; Debernard, Jens B.</p> <p>2018-04-01</p> <p>An increasing number of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> models now include <span class="hlt">Antarctic</span> ice-shelf cavities, and simulate thermodynamics at the ice-shelf/<span class="hlt">ocean</span> interface. This adds another level of complexity to <span class="hlt">Southern</span> <span class="hlt">Ocean</span> simulations, as ice shelves interact directly with the <span class="hlt">ocean</span> and indirectly with sea ice. Here, we present the first model intercomparison and evaluation of present-day <span class="hlt">ocean</span>/sea-ice/ice-shelf interactions, as simulated by two models: a circumpolar <span class="hlt">Antarctic</span> configuration of MetROMS (ROMS: Regional <span class="hlt">Ocean</span> Modelling System coupled to CICE: Community Ice CodE) and the global model FESOM (Finite Element Sea-ice <span class="hlt">Ocean</span> Model), where the latter is run at two different levels of horizontal resolution. From a circumpolar <span class="hlt">Antarctic</span> perspective, we compare and evaluate simulated ice-shelf basal melting and sub-ice-shelf circulation, as well as sea-ice properties and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> water mass characteristics as they influence the sub-ice-shelf processes. Despite their differing numerical methods, the two models produce broadly similar results and share similar biases in many cases. Both models reproduce many key features of observations but struggle to reproduce others, such as the high melt rates observed in the small warm-cavity ice shelves of the Amundsen and Bellingshausen seas. Several differences in model design show a particular influence on the simulations. For example, FESOM's greater topographic smoothing can alter the geometry of some ice-shelf cavities enough to affect their melt rates; this improves at higher resolution, since less smoothing is required. In the interior <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, the vertical coordinate system affects the degree of water mass erosion due to spurious diapycnal mixing, with MetROMS' terrain-following coordinate leading to more erosion than FESOM's z coordinate. Finally, increased horizontal resolution in FESOM leads to higher basal melt rates for small ice shelves, through a combination of stronger circulation and small-scale intrusions of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21814203','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21814203"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> dust-climate coupling over the past four million years.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Martínez-Garcia, Alfredo; Rosell-Melé, Antoni; Jaccard, Samuel L; Geibert, Walter; Sigman, Daniel M; Haug, Gerald H</p> <p>2011-08-03</p> <p>Dust has the potential to modify global climate by influencing the radiative balance of the atmosphere and by supplying iron and other essential limiting micronutrients to the <span class="hlt">ocean</span>. Indeed, dust supply to the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> increases during ice ages, and 'iron fertilization' of the subantarctic zone may have contributed up to 40 parts per million by volume (p.p.m.v.) of the decrease (80-100 p.p.m.v.) in atmospheric carbon dioxide observed during late Pleistocene glacial cycles. So far, however, the magnitude of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> dust deposition in earlier times and its role in the development and evolution of Pleistocene glacial cycles have remained unclear. Here we report a high-resolution record of dust and iron supply to the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> over the past four million years, derived from the analysis of marine sediments from ODP Site 1090, located in the Atlantic sector of the subantarctic zone. The close correspondence of our dust and iron deposition records with <span class="hlt">Antarctic</span> ice core reconstructions of dust flux covering the past 800,000 years (refs 8, 9) indicates that both of these archives record large-scale deposition changes that should apply to most of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, validating previous interpretations of the ice core data. The extension of the record beyond the interval covered by the <span class="hlt">Antarctic</span> ice cores reveals that, in contrast to the relatively gradual intensification of glacial cycles over the past three million years, <span class="hlt">Southern</span> <span class="hlt">Ocean</span> dust and iron flux rose sharply at the Mid-Pleistocene climatic transition around 1.25 million years ago. This finding complements previous observations over late Pleistocene glacial cycles, providing new evidence of a tight connection between high dust input to the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and the emergence of the deep glaciations that characterize the past one million years of Earth history.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.7564M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.7564M"><span>A Tale of Two Forcings: Present-Day Coupled <span class="hlt">Antarctic</span> Ice-sheet/<span class="hlt">Southern</span> <span class="hlt">Ocean</span> dynamics using the POPSICLES model.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martin, Daniel; Asay-Davis, Xylar; Cornford, Stephen; Price, Stephen; Ng, Esmond; Collins, William</p> <p>2015-04-01</p> <p>We present POPSICLES simulation results covering the full <span class="hlt">Antarctic</span> Ice Sheet and the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> spanning the period 1990 to 2010 resulting from two different choices of climate forcing: a 'normal-year' climatology and the CORE v. 2 interannual forcing data (Large and Yeager 2008). Simulations are performed at 0.1o (~5 km) <span class="hlt">ocean</span> resolution and adaptive ice sheet resolution as fine as 500 m. We compare time-averaged melt rates below a number of major ice shelves with those reported by Rignot et al. (2013) as well as other recent studies. We also present seasonal variability and decadal melting trends from several <span class="hlt">Antarctic</span> regions, along with the response of the ice shelves and consequent dynamics of the grounded ice sheet. POPSICLES couples the POP2x <span class="hlt">ocean</span> model, a modified version of the Parallel <span class="hlt">Ocean</span> Program (Smith and Gent, 2002), and the BISICLES ice-sheet model (Cornford et al., 2012). POP2x includes sub-ice-shelf circulation using partial top cells (Losch, 2008) and boundary layer physics following Holland and Jenkins (1999), Jenkins (2001), and Jenkins et al. (2010). Standalone POP2x output compares well with standard ice-<span class="hlt">ocean</span> test cases (e.g., ISOMIP; Losch, 2008) and other continental-scale simulations and melt-rate observations (Kimura et al., 2013; Rignot et al., 2013). BISICLES makes use of adaptive mesh refinement and a 1st-order accurate momentum balance similar to the L1L2 model of Schoof and Hindmarsh (2009) to accurately model regions of dynamic complexity, such as ice streams, outlet glaciers, and grounding lines. Results of BISICLES simulations have compared favorably to comparable simulations with a Stokes momentum balance in both idealized tests (MISMIP-3d; Pattyn et al., 2013) and realistic configurations (Favier et al. 2014).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70156091','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70156091"><span>Water masses, <span class="hlt">ocean</span> fronts, and the structure of <span class="hlt">Antarctic</span> seabird communities: putting the eastern Bellingshausen Sea in perspective</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ribic, Christine A.; Ainley, David G.; Ford, R. Glenn; Fraser, William R.; Tynan, Cynthia T.; Woehler, Eric J.</p> <p>2015-01-01</p> <p>Waters off the western <span class="hlt">Antarctic</span> Peninsula (i.e., the eastern Bellingshausen Sea) are unusually complex owing to the convergence of several major fronts. Determining the relative influence of fronts on occurrence patterns of top-trophic species in that area, therefore, has been challenging. In one of the few <span class="hlt">ocean</span>-wide seabird data syntheses, in this case for the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, we analyzed ample, previously collected cruise data, <span class="hlt">Antarctic</span>-wide, to determine seabird species assemblages and quantitative relationships to fronts as a way to provide context to the long-term Palmer LTER and the winter <span class="hlt">Southern</span> <span class="hlt">Ocean</span> GLOBEC studies in the eastern Bellingshausen Sea. Fronts investigated during both winter (April–September) and summer (October–March) were the <span class="hlt">southern</span> boundary of the <span class="hlt">Antarctic</span> Circumpolar Current (ACC), which separates the High <span class="hlt">Antarctic</span> from the Low <span class="hlt">Antarctic</span> water mass, and within which are embedded the marginal ice zone and <span class="hlt">Antarctic</span> Shelf Break Front; and the <span class="hlt">Antarctic</span> Polar Front, which separates the Low <span class="hlt">Antarctic</span> and the Subantarctic water masses. We used clustering to determine species' groupings with water masses, and generalized additive models to relate species' densities, biomass and diversity to distance to respective fronts. <span class="hlt">Antarctic</span>-wide, in both periods, highest seabird densities and lowest species diversity were found in the High <span class="hlt">Antarctic</span> water mass. In the eastern Bellingshausen, seabird density in the High <span class="hlt">Antarctic</span> water mass was lower (as low as half that of winter) than found in other <span class="hlt">Antarctic</span> regions. During winter, <span class="hlt">Antarctic</span>-wide, two significant species groups were evident: one dominated by Adélie penguins (Pygoscelis adeliae) (High <span class="hlt">Antarctic</span> water mass) and the other by petrels and prions (no differentiation among water masses); in eastern Bellingshausen waters during winter, the one significant species group was composed of species from both <span class="hlt">Antarctic</span>-wide groups. In summer, <span class="hlt">Antarctic</span>-wide, a High <span class="hlt">Antarctic</span> group</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2881033','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2881033"><span>Shearwater Foraging in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>: The Roles of Prey Availability and Winds</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Raymond, Ben; Shaffer, Scott A.; Sokolov, Serguei; Woehler, Eric J.; Costa, Daniel P.; Einoder, Luke; Hindell, Mark; Hosie, Graham; Pinkerton, Matt; Sagar, Paul M.; Scott, Darren; Smith, Adam; Thompson, David R.; Vertigan, Caitlin; Weimerskirch, Henri</p> <p>2010-01-01</p> <p>Background Sooty (Puffinus griseus) and short-tailed (P. tenuirostris) shearwaters are abundant seabirds that range widely across global <span class="hlt">oceans</span>. Understanding the foraging ecology of these species in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is important for monitoring and ecosystem conservation and management. Methodology/Principal Findings Tracking data from sooty and short-tailed shearwaters from three regions of New Zealand and Australia were combined with at-sea observations of shearwaters in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, physical oceanography, near-surface copepod distributions, pelagic trawl data, and synoptic near-surface winds. Shearwaters from all three regions foraged in the Polar Front zone, and showed particular overlap in the region around 140°E. Short-tailed shearwaters from South Australia also foraged in <span class="hlt">Antarctic</span> waters south of the Polar Front. The spatial distribution of shearwater foraging effort in the Polar Front zone was matched by patterns in large-scale upwelling, primary production, and abundances of copepods and myctophid fish. <span class="hlt">Oceanic</span> winds were found to be broad determinants of foraging distribution, and of the flight paths taken by the birds on long foraging trips to <span class="hlt">Antarctic</span> waters. Conclusions/Significance The shearwaters displayed foraging site fidelity and overlap of foraging habitat between species and populations that may enhance their utility as indicators of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ecosystems. The results highlight the importance of upwellings due to interactions of the <span class="hlt">Antarctic</span> Circumpolar Current with large-scale bottom topography, and the corresponding localised increases in the productivity of the Polar Front ecosystem. PMID:20532034</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28054598','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28054598"><span><span class="hlt">Antarctic</span> ice sheet discharge driven by atmosphere-<span class="hlt">ocean</span> feedbacks at the Last Glacial Termination.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fogwill, C J; Turney, C S M; Golledge, N R; Etheridge, D M; Rubino, M; Thornton, D P; Baker, A; Woodward, J; Winter, K; van Ommen, T D; Moy, A D; Curran, M A J; Davies, S M; Weber, M E; Bird, M I; Munksgaard, N C; Menviel, L; Rootes, C M; Ellis, B; Millman, H; Vohra, J; Rivera, A; Cooper, A</p> <p>2017-01-05</p> <p>Reconstructing the dynamic response of the <span class="hlt">Antarctic</span> ice sheets to warming during the Last Glacial Termination (LGT; 18,000-11,650 yrs ago) allows us to disentangle ice-climate feedbacks that are key to improving future projections. Whilst the sequence of events during this period is reasonably well-known, relatively poor chronological control has precluded precise alignment of ice, atmospheric and marine records, making it difficult to assess relationships between <span class="hlt">Antarctic</span> ice-sheet (AIS) dynamics, climate change and sea level. Here we present results from a highly-resolved 'horizontal ice core' from the Weddell Sea Embayment, which records millennial-scale AIS dynamics across this extensive region. Counterintuitively, we find AIS mass-loss across the full duration of the <span class="hlt">Antarctic</span> Cold Reversal (ACR; 14,600-12,700 yrs ago), with stabilisation during the subsequent millennia of atmospheric warming. Earth-system and ice-sheet modelling suggests these contrasting trends were likely <span class="hlt">Antarctic</span>-wide, sustained by feedbacks amplified by the delivery of Circumpolar Deep Water onto the continental shelf. Given the anti-phase relationship between inter-hemispheric climate trends across the LGT our findings demonstrate that <span class="hlt">Southern</span> <span class="hlt">Ocean</span>-AIS feedbacks were controlled by global atmospheric teleconnections. With increasing stratification of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and intensification of mid-latitude westerly winds today, such teleconnections could amplify AIS mass loss and accelerate global sea-level rise.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5954465','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5954465"><span>Shelf–<span class="hlt">ocean</span> exchange and hydrography west of the <span class="hlt">Antarctic</span> Peninsula: a review</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2018-01-01</p> <p>The West <span class="hlt">Antarctic</span> Peninsula (WAP) is a highly productive marine ecosystem where extended periods of change have been observed in the form of glacier retreat, reduction of sea-ice cover and shifts in marine populations, among others. The physical environment on the shelf is known to be strongly influenced by the <span class="hlt">Antarctic</span> Circumpolar Current flowing along the shelf slope and carrying warm, nutrient-rich water, by cold waters flooding into the northern Bransfield Strait from the Weddell Sea, by an extensive network of glaciers and ice shelves, and by strong seasonal to inter-annual variability in sea-ice formation and air–sea interactions, with significant modulation by climate modes like El Niño–<span class="hlt">Southern</span> Oscillation and the <span class="hlt">Southern</span> Annular Mode. However, significant gaps have remained in understanding the exchange processes between the open <span class="hlt">ocean</span> and the shelf, the pathways and fate of <span class="hlt">oceanic</span> water intrusions, the shelf heat and salt budgets, and the long-term evolution of the shelf properties and circulation. Here, we review how recent advances in long-term monitoring programmes, process studies and newly developed numerical models have helped bridge these gaps and set future research challenges for the WAP system. This article is part of the theme issue ‘The marine system of the West <span class="hlt">Antarctic</span> Peninsula: status and strategy for progress in a region of rapid change’. PMID:29760109</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.C33A0376M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.C33A0376M"><span>Response of the <span class="hlt">Antarctic</span> ice sheet to <span class="hlt">ocean</span> forcing using the POPSICLES coupled ice sheet-<span class="hlt">ocean</span> model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martin, D. F.; Asay-Davis, X.; Price, S. F.; Cornford, S. L.; Maltrud, M. E.; Ng, E. G.; Collins, W.</p> <p>2014-12-01</p> <p>We present the response of the continental <span class="hlt">Antarctic</span> ice sheet to sub-shelf-melt forcing derived from POPSICLES simulation results covering the full <span class="hlt">Antarctic</span> Ice Sheet and the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> spanning the period 1990 to 2010. Simulations are performed at 0.1 degree (~5 km) <span class="hlt">ocean</span> resolution and ice sheet resolution as fine as 500 m using adaptive mesh refinement. A comparison of fully-coupled and comparable standalone ice-sheet model results demonstrates the importance of two-way coupling between the ice sheet and the <span class="hlt">ocean</span>. The POPSICLES model couples the POP2x <span class="hlt">ocean</span> model, a modified version of the Parallel <span class="hlt">Ocean</span> Program (Smith and Gent, 2002), and the BISICLES ice-sheet model (Cornford et al., 2012). BISICLES makes use of adaptive mesh refinement to fully resolve dynamically-important regions like grounding lines and employs a momentum balance similar to the vertically-integrated formulation of Schoof and Hindmarsh (2009). Results of BISICLES simulations have compared favorably to comparable simulations with a Stokes momentum balance in both idealized tests like MISMIP3D (Pattyn et al., 2013) and realistic configurations (Favier et al. 2014). POP2x includes sub-ice-shelf circulation using partial top cells (Losch, 2008) and boundary layer physics following Holland and Jenkins (1999), Jenkins (2001), and Jenkins et al. (2010). Standalone POP2x output compares well with standard ice-<span class="hlt">ocean</span> test cases (e.g., ISOMIP; Losch, 2008) and other continental-scale simulations and melt-rate observations (Kimura et al., 2013; Rignot et al., 2013). A companion presentation, "Present-day circum-<span class="hlt">Antarctic</span> simulations using the POPSICLES coupled land ice-<span class="hlt">ocean</span> model" in session C027 describes the <span class="hlt">ocean</span>-model perspective of this work, while we focus on the response of the ice sheet and on details of the model. The figure shows the BISICLES-computed vertically-integrated ice velocity field about 1 month into a 20-year coupled <span class="hlt">Antarctic</span> run. Groundling lines are shown in green.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18765160','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18765160"><span>Environmental contamination in <span class="hlt">Antarctic</span> ecosystems.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bargagli, R</p> <p>2008-08-01</p> <p>Although the remote continent of Antarctica is perceived as the symbol of the last great wilderness, the human presence in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and the continent began in the early 1900s for hunting, fishing and exploration, and many invasive plant and animal species have been deliberately introduced in several sub-<span class="hlt">Antarctic</span> islands. Over the last 50 years, the development of research and tourism have locally affected terrestrial and marine coastal ecosystems through fuel combustion (for transportation and energy production), accidental oil spills, waste incineration and sewage. Although natural "barriers" such as <span class="hlt">oceanic</span> and atmospheric circulation protect Antarctica from lower latitude water and air masses, available data on concentrations of metals, pesticides and other persistent pollutants in air, snow, mosses, lichens and marine organisms show that most persistent contaminants in the <span class="hlt">Antarctic</span> environment are transported from other continents in the <span class="hlt">Southern</span> Hemisphere. At present, levels of most contaminants in <span class="hlt">Antarctic</span> organisms are lower than those in related species from other remote regions, except for the natural accumulation of Cd and Hg in several marine organisms and especially in albatrosses and petrels. The concentrations of organic pollutants in the eggs of an opportunistic top predator such as the south polar skua are close to those that may cause adverse health effects. Population growth and industrial development in several countries of the <span class="hlt">Southern</span> Hemisphere are changing the global pattern of persistent anthropogenic contaminants and new classes of chemicals have already been detected in the <span class="hlt">Antarctic</span> environment. Although the Protocol on Environmental Protection to the <span class="hlt">Antarctic</span> Treaty provides strict guidelines for the protection of the <span class="hlt">Antarctic</span> environment and establishes obligations for all human activity in the continent and the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, global warming, population growth and industrial development in countries of the <span class="hlt">Southern</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C21A0687M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C21A0687M"><span>Decadal-Scale Response of the <span class="hlt">Antarctic</span> Ice sheet to a Warming <span class="hlt">Ocean</span> using the POPSICLES Coupled Ice Sheet-<span class="hlt">Ocean</span> model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martin, D. F.; Asay-Davis, X.; Cornford, S. L.; Price, S. F.; Ng, E. G.; Collins, W.</p> <p>2015-12-01</p> <p>We present POPSICLES simulation results covering the full <span class="hlt">Antarctic</span> Ice Sheet and the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> spanning the period from 1990 to 2010. We use the CORE v. 2 interannual forcing data to force the <span class="hlt">ocean</span> model. Simulations are performed at 0.1o(~5 km) <span class="hlt">ocean</span> resolution with adaptive ice sheet resolution as fine as 500 m to adequately resolve the grounding line dynamics. We discuss the effect of improved <span class="hlt">ocean</span> mixing and subshelf bathymetry (vs. the standard Bedmap2 bathymetry) on the behavior of the coupled system, comparing time-averaged melt rates below a number of major ice shelves with those reported in the literature. We also present seasonal variability and decadal melting trends from several <span class="hlt">Antarctic</span> regions, along with the response of the ice shelves and the consequent dynamic response of the grounded ice sheet.POPSICLES couples the POP2x <span class="hlt">ocean</span> model, a modified version of the Parallel <span class="hlt">Ocean</span> Program, and the BISICLES ice-sheet model. POP2x includes sub-ice-shelf circulation using partial top cells and the commonly used three-equation boundary layer physics. Standalone POP2x output compares well with standard ice-<span class="hlt">ocean</span> test cases (e.g., ISOMIP) and other continental-scale simulations and melt-rate observations. BISICLES makes use of adaptive mesh refinement and a 1st-order accurate momentum balance similar to the L1L2 model of Schoof and Hindmarsh to accurately model regions of dynamic complexity, such as ice streams, outlet glaciers, and grounding lines. Results of BISICLES simulations have compared favorably to comparable simulations with a Stokes momentum balance in both idealized tests (MISMIP-3d) and realistic configurations.The figure shows the BISICLES-computed vertically-integrated grounded ice velocity field 5 years into a 20-year coupled full-continent <span class="hlt">Antarctic-Southern-Ocean</span> simulation. Submarine melt rates are painted onto the surface of the floating ice shelves. Grounding lines are shown in green.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active"><span>4</span></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_4 --> <div id="page_5" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="81"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRF..122..153A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRF..122..153A"><span>Links between atmosphere, <span class="hlt">ocean</span>, and cryosphere from two decades of microseism observations on the <span class="hlt">Antarctic</span> Peninsula</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Anthony, Robert E.; Aster, Richard C.; McGrath, Daniel</p> <p>2017-01-01</p> <p>The lack of landmasses, climatological low pressure, and strong circumpolar westerly winds between the latitudes of 50°S to 65°S produce exceptional storm-driven wave conditions in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. This combination makes the <span class="hlt">Antarctic</span> Peninsula one of Earth's most notable regions of high-amplitude wave activity and thus, <span class="hlt">ocean</span>-swell-driven microseism noise in both the primary (direct wave-coastal region interactions) and secondary (direct <span class="hlt">ocean</span> floor forcing due to interacting wave trains) period bands. Microseism observations are examined across 23 years (1993-2015) from Palmer Station (PMSA), on the west coast of the <span class="hlt">Antarctic</span> Peninsula, and from East Falkland Island (EFI). These records provide a spatially integrative measure of both <span class="hlt">Southern</span> <span class="hlt">Ocean</span> wave amplitudes and the interactions between <span class="hlt">ocean</span> waves and the solid Earth in the presence of sea ice, which can reduce wave coupling with the continental shelf. We utilize a spatiotemporal correlation-based approach to illuminate how the distribution of sea ice influences seasonal microseism power. We characterize primary and secondary microseism power due to variations in sea ice and find that primary microseism energy is both more sensitive to sea ice and more capable of propagating across <span class="hlt">ocean</span> basins than secondary microseism energy. During positive phases of the <span class="hlt">Southern</span> Annular Mode, sea ice is reduced in the Bellingshausen Sea and overall storm activity in the Drake Passage increases, thus strongly increasing microseism power levels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PrOce.159....1M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PrOce.159....1M"><span>A biologically relevant method for considering patterns of <span class="hlt">oceanic</span> retention in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mori, Mao; Corney, Stuart P.; Melbourne-Thomas, Jessica; Klocker, Andreas; Sumner, Michael; Constable, Andrew</p> <p>2017-12-01</p> <p>Many marine species have planktonic forms - either during a larval stage or throughout their lifecycle - that move passively or are strongly influenced by <span class="hlt">ocean</span> currents. Understanding these patterns of movement is important for informing marine ecosystem management and for understanding ecological processes generally. Retention of biological particles in a particular area due to <span class="hlt">ocean</span> currents has received less attention than transport pathways, particularly for the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. We present a method for modelling retention time, based on the half-life for particles in a particular region, that is relevant for biological processes. This method uses geostrophic velocities at the <span class="hlt">ocean</span> surface, derived from 23 years of satellite altimetry data (1993-2016), to simulate the advection of passive particles during the <span class="hlt">Southern</span> Hemisphere summer season (from December to March). We assess spatial patterns in the retention time of passive particles and evaluate the processes affecting these patterns for the Indian sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Our results indicate that the distribution of retention time is related to bathymetric features and the resulting <span class="hlt">ocean</span> dynamics. Our analysis also reveals a moderate level of consistency between spatial patterns of retention time and observations of <span class="hlt">Antarctic</span> krill (Euphausia superba) distribution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017NatCC...7..749G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NatCC...7..749G"><span>More losers than winners in a century of future <span class="hlt">Southern</span> <span class="hlt">Ocean</span> seafloor warming</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Griffiths, Huw J.; Meijers, Andrew J. S.; Bracegirdle, Thomas J.</p> <p>2017-10-01</p> <p>The waters of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> are projected to warm over the coming century, with potential adverse consequences for native cold-adapted organisms. Warming waters have caused temperate marine species to shift their ranges poleward. The seafloor animals of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> shelf have long been isolated by the deep <span class="hlt">ocean</span> surrounding Antarctica and the <span class="hlt">Antarctic</span> Circumpolar Current, with little scope for southward migration. How these largely endemic species will react to future projected warming is unknown. By considering 963 invertebrate species, we show that within the current century, warming temperatures alone are unlikely to result in wholesale extinction or invasion affecting <span class="hlt">Antarctic</span> seafloor life. However, 79% of Antarctica's endemic species do face a significant reduction in suitable temperature habitat (an average 12% reduction). Our findings highlight the species and regions most likely to respond significantly (negatively and positively) to warming and have important implications for future management of the region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001OcMod...3...51G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001OcMod...3...51G"><span>The sources of <span class="hlt">Antarctic</span> bottom water in a global ice <span class="hlt">ocean</span> model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goosse, Hugues; Campin, Jean-Michel; Tartinville, Benoı̂t</p> <p></p> <p>Two mechanisms contribute to the formation of <span class="hlt">Antarctic</span> bottom water (AABW). The first, and probably the most important, is initiated by the brine released on the <span class="hlt">Antarctic</span> continental shelf during ice formation which is responsible for an increase in salinity. After mixing with ambient water at the shelf break, this salty and dense water sinks along the shelf slope and invades the deepest part of the global <span class="hlt">ocean</span>. For the second one, the increase of surface water density is due to strong cooling at the <span class="hlt">ocean</span>-atmosphere interface, together with a contribution from brine release. This induces deep convection and the renewal of deep waters. The relative importance of these two mechanisms is investigated in a global coupled ice-<span class="hlt">ocean</span> model. Chlorofluorocarbon (CFC) concentrations simulated by the model compare favourably with observations, suggesting a reasonable deep water ventilation in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, except close to Antarctica where concentrations are too high. Two artificial passive tracers released at surface on the <span class="hlt">Antarctic</span> continental shelf and in the open-<span class="hlt">ocean</span> allow to show clearly that the two mechanisms contribute significantly to the renewal of AABW in the model. This indicates that open-<span class="hlt">ocean</span> convection is overestimated in our simulation. Additional experiments show that the amount of AABW production due to the export of dense shelf waters is quite sensitive to the parameterisation of the effect of downsloping and meso-scale eddies. Nevertheless, shelf waters always contribute significantly to deep water renewal. Besides, increasing the P.R. Gent, J.C. McWilliams [Journal of Physical Oceanography 20 (1990) 150-155] thickness diffusion can nearly suppress the AABW formation by open-<span class="hlt">ocean</span> convection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1715192B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1715192B"><span>Dynamics of the Oligocene <span class="hlt">Southern</span> <span class="hlt">Ocean</span>: dinocysts as surface paleoceanographic tracers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bijl, Peter; Houben, Alexander; Brinkhuis, Henk; Sangiorgi, Francesca</p> <p>2015-04-01</p> <p>The Oligocene Epoch (33.9-23 Ma) is the time interval in the Cenozoic that saw the establishment of a continental-scale <span class="hlt">Antarctic</span> ice-sheet. There remains a controversy about whether this early episode of a glaciated Antarctica was stable, or whether dynamic ice conditions prevailed. Most of this controversy persists due to the absence of chronostratigraphically well-dated sedimentary archives from close to the east <span class="hlt">Antarctic</span> ice sheet, which has recorded a direct signal of glacial dynamics. Another major question is how the Oligocene <span class="hlt">Southern</span> <span class="hlt">Ocean</span> responded to the glaciation and subsequent evolution of the ice sheet, as the <span class="hlt">Southern</span> <span class="hlt">ocean</span> is a major player in global <span class="hlt">ocean</span> circulation. Numerical modelling studies suggest that alongside the buildup of continental ice on Antarctica, first sea-ice conditions may have started along the East <span class="hlt">Antarctic</span> Margin, but this conclusion lacks support from field evidence. Other numerical models predict that hysteresis effects within the ice sheet will make a continental-size <span class="hlt">Antarctic</span> ice sheet rather insensitive to warming. In contrast, deep-water benthic foraminiferal oxygen isotope records across the Oligocene suggest dramatic waxing and waning of <span class="hlt">Antarctic</span> ice sheets. This paradox is as yet not solved Integrated <span class="hlt">Ocean</span> Drilling Expedition 318 drilled the <span class="hlt">Antarctic</span> Margin in 2010, and recovered sediments from the early phase of <span class="hlt">Antarctic</span> glaciation. With this record, we can now evaluate the robustness of the results of the numerical models and the oceanographic changes with field data. Sediments recovered from Site U1356 yield a thick and relatively complete (albeit compromised by core gaps) Oligocene succession both of which are chrono-stratigraphically well-calibrated with use of nannoplankton- dinocyst- and magnetostratigraphy. Notably, this record yields well-preserved dinoflagellate cysts (dinocysts), which we can use to investigate surface-water condition changes across the Eocene-Oligocene to provide answers to these</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMOS13A2018B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS13A2018B"><span>Population-Level Transcriptomic Responses of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Salp Salpa thompsoni to Environment Variability of the Western <span class="hlt">Antarctic</span> Peninsula Region</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bucklin, A. C.; Batta Lona, P. G.; Maas, A. E.; O'Neill, R. J.; Wiebe, P. H.</p> <p>2015-12-01</p> <p>In response to the changing <span class="hlt">Antarctic</span> climate, the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> salp Salpa thompsoni has shown altered patterns of distribution and abundance that are anticipated to have profound impacts on pelagic food webs and ecosystem dynamics. The physiological and molecular processes that underlay ecological function and biogeographical distribution are key to understanding present-day dynamics and predicting future trajectories. This study examined transcriptome-wide patterns of gene expression in relation to biological and physical oceanographic conditions in coastal, shelf and offshore waters of the Western <span class="hlt">Antarctic</span> Peninsula (WAP) region during austral spring and summer 2011. Based on field observations and collections, seasonal changes in the distribution and abundance of salps of different life stages were associated with differences in water mass structure of the WAP. Our observations are consistent with previous suggestions that bathymetry and currents in Bransfield Strait could generate a retentive cell for an overwintering population of S. thompsoni, which may generate the characteristic salp blooms found throughout the region later in summer. The statistical analysis of transcriptome-wide patterns of gene expression revealed differences among salps collected in different seasons and from different habitats (i.e., coastal versus offshore) in the WAP. Gene expression patterns also clustered by station in austral spring - but not summer - collections, suggesting stronger heterogeneity of environmental conditions. During the summer, differentially expressed genes covered a wider range of functions, including those associated with stress responses. Future research using novel molecular transcriptomic / genomic characterization of S. thompsoni will allow more complete understanding of individual-, population-, and species-level responses to environmental variability and prediction of future dynamics of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> food webs and ecosystems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018BGeo...15...31T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018BGeo...15...31T"><span>Distribution of planktonic biogenic carbonate organisms in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> south of Australia: a baseline for <span class="hlt">ocean</span> acidification impact assessment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Trull, Thomas W.; Passmore, Abraham; Davies, Diana M.; Smit, Tim; Berry, Kate; Tilbrook, Bronte</p> <p>2018-01-01</p> <p>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> provides a vital service by absorbing about one-sixth of humankind's annual emissions of CO2. This comes with a cost - an increase in <span class="hlt">ocean</span> acidity that is expected to have negative impacts on <span class="hlt">ocean</span> ecosystems. The reduced ability of phytoplankton and zooplankton to precipitate carbonate shells is a clearly identified risk. The impact depends on the significance of these organisms in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ecosystems, but there is very little information on their abundance or distribution. To quantify their presence, we used coulometric measurement of particulate inorganic carbonate (PIC) on particles filtered from surface seawater into two size fractions: 50-1000 µm to capture foraminifera (the most important biogenic carbonate-forming zooplankton) and 1-50 µm to capture coccolithophores (the most important biogenic carbonate-forming phytoplankton). Ancillary measurements of biogenic silica (BSi) and particulate organic carbon (POC) provided context, as estimates of the biomass of diatoms (the highest biomass phytoplankton in polar waters) and total microbial biomass, respectively. Results for nine transects from Australia to Antarctica in 2008-2015 showed low levels of PIC compared to Northern Hemisphere polar waters. Coccolithophores slightly exceeded the biomass of diatoms in subantarctic waters, but their abundance decreased more than 30-fold poleward, while diatom abundances increased, so that on a molar basis PIC was only 1 % of BSi in <span class="hlt">Antarctic</span> waters. This limited importance of coccolithophores in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is further emphasized in terms of their associated POC, representing less than 1 % of total POC in <span class="hlt">Antarctic</span> waters and less than 10 % in subantarctic waters. NASA satellite <span class="hlt">ocean</span>-colour-based PIC estimates were in reasonable agreement with the shipboard results in subantarctic waters but greatly overestimated PIC in <span class="hlt">Antarctic</span> waters. Contrastingly, the NASA <span class="hlt">Ocean</span> Biogeochemical Model (NOBM) shows coccolithophores as overly</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12154613','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12154613"><span>Ecology of <span class="hlt">southern</span> <span class="hlt">ocean</span> pack ice.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Brierley, Andrew S; Thomas, David N</p> <p>2002-01-01</p> <p>Around Antarctica the annual five-fold growth and decay of sea ice is the most prominent physical process and has a profound impact on marine life there. In winter the pack ice canopy extends to cover almost 20 million square kilometres--some 8% of the <span class="hlt">southern</span> hemisphere and an area larger than the <span class="hlt">Antarctic</span> continent itself (13.2 million square kilometres)--and is one of the largest, most dynamic ecosystems on earth. Biological activity is associated with all physical components of the sea-ice system: the sea-ice surface; the internal sea-ice matrix and brine channel system; the underside of sea ice and the waters in the vicinity of sea ice that are modified by the presence of sea ice. Microbial and microalgal communities proliferate on and within sea ice and are grazed by a wide range of proto- and macrozooplankton that inhabit the sea ice in large concentrations. Grazing organisms also exploit biogenic material released from the sea ice at ice break-up or melt. Although rates of primary production in the underlying water column are often low because of shading by sea-ice cover, sea ice itself forms a substratum that provides standing stocks of bacteria, algae and grazers significantly higher than those in ice-free areas. Decay of sea ice in summer releases particulate and dissolved organic matter to the water column, playing a major role in biogeochemical cycling as well as seeding water column phytoplankton blooms. Numerous zooplankton species graze sea-ice algae, benefiting additionally because the overlying sea-ice ceiling provides a refuge from surface predators. Sea ice is an important nursery habitat for <span class="hlt">Antarctic</span> krill, the pivotal species in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> marine ecosystem. Some deep-water fish migrate to shallow depths beneath sea ice to exploit the elevated concentrations of some zooplankton there. The increased secondary production associated with pack ice and the sea-ice edge is exploited by many higher predators, with seals, seabirds and whales</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMPA32A..01W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMPA32A..01W"><span>A Strategic Vision for NSF Investments in <span class="hlt">Antarctic</span> and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Research: Recommendations of a New Study from the National Academes of Sciences, Engineering, and Medicine.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weller, R. A.; Bell, R. E.; Geller, L.</p> <p>2015-12-01</p> <p>A Committee convened by the National Academies of Sciences, Engineering, and Medicine carried out a study (at the request of NSF's Division of Polar Programs) to develop a strategic vision for the coming decade of NSF's investments in <span class="hlt">Antarctic</span> and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> research. The study was informed by extensive efforts to gather ideas from researchers across the United States. This presentation will provide an overview of the Committee's recommendations—regarding an overall strategic framework for a robust U.S. <span class="hlt">Antarctic</span> program, regarding the specific areas of research recommended as highest priority for NSF support, and regarding the types of infrastructure, logistical support, data management, and other critical foundations for enabling and adding lasting value to the proposed research .</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PNAS..114.3352W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PNAS..114.3352W"><span>Deep-sea coral evidence for lower <span class="hlt">Southern</span> <span class="hlt">Ocean</span> surface nitrate concentrations during the last ice age</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Xingchen Tony; Sigman, Daniel M.; Prokopenko, Maria G.; Adkins, Jess F.; Robinson, Laura F.; Hines, Sophia K.; Chai, Junyi; Studer, Anja S.; Martínez-García, Alfredo; Chen, Tianyu; Haug, Gerald H.</p> <p>2017-03-01</p> <p>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> regulates the ocean’s biological sequestration of CO2 and is widely suspected to underpin much of the ice age decline in atmospheric CO2 concentration, but the specific changes in the region are debated. Although more complete drawdown of surface nutrients by phytoplankton during the ice ages is supported by some sediment core-based measurements, the use of different proxies in different regions has precluded a unified view of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> biogeochemical change. Here, we report measurements of the 15N/14N of fossil-bound organic matter in the stony deep-sea coral Desmophyllum dianthus, a tool for reconstructing surface <span class="hlt">ocean</span> nutrient conditions. The central robust observation is of higher 15N/14N across the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> during the Last Glacial Maximum (LGM), 18-25 thousand years ago. These data suggest a reduced summer surface nitrate concentration in both the <span class="hlt">Antarctic</span> and Subantarctic Zones during the LGM, with little surface nitrate transport between them. After the ice age, the increase in <span class="hlt">Antarctic</span> surface nitrate occurred through the deglaciation and continued in the Holocene. The rise in Subantarctic surface nitrate appears to have had both early deglacial and late deglacial/Holocene components, preliminarily attributed to the end of Subantarctic iron fertilization and increasing nitrate input from the surface <span class="hlt">Antarctic</span> Zone, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5380069','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5380069"><span>Deep-sea coral evidence for lower <span class="hlt">Southern</span> <span class="hlt">Ocean</span> surface nitrate concentrations during the last ice age</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Sigman, Daniel M.; Prokopenko, Maria G.; Adkins, Jess F.; Robinson, Laura F.; Hines, Sophia K.; Chai, Junyi; Studer, Anja S.; Martínez-García, Alfredo; Chen, Tianyu; Haug, Gerald H.</p> <p>2017-01-01</p> <p>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> regulates the ocean’s biological sequestration of CO2 and is widely suspected to underpin much of the ice age decline in atmospheric CO2 concentration, but the specific changes in the region are debated. Although more complete drawdown of surface nutrients by phytoplankton during the ice ages is supported by some sediment core-based measurements, the use of different proxies in different regions has precluded a unified view of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> biogeochemical change. Here, we report measurements of the 15N/14N of fossil-bound organic matter in the stony deep-sea coral Desmophyllum dianthus, a tool for reconstructing surface <span class="hlt">ocean</span> nutrient conditions. The central robust observation is of higher 15N/14N across the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> during the Last Glacial Maximum (LGM), 18–25 thousand years ago. These data suggest a reduced summer surface nitrate concentration in both the <span class="hlt">Antarctic</span> and Subantarctic Zones during the LGM, with little surface nitrate transport between them. After the ice age, the increase in <span class="hlt">Antarctic</span> surface nitrate occurred through the deglaciation and continued in the Holocene. The rise in Subantarctic surface nitrate appears to have had both early deglacial and late deglacial/Holocene components, preliminarily attributed to the end of Subantarctic iron fertilization and increasing nitrate input from the surface <span class="hlt">Antarctic</span> Zone, respectively. PMID:28298529</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMPP31C2283B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMPP31C2283B"><span>Large Scale Eocene <span class="hlt">Ocean</span> Circulation Transition Could Help <span class="hlt">Antarctic</span> Glaciation.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baatsen, M.</p> <p>2016-12-01</p> <p>The global climate underwent major changes going from the Eocene into the Oligocene, including the formation of a continental-scale <span class="hlt">Antarctic</span> ice sheet. In addition to a gradual drawdown of CO2 since the Early Eocene, the changing background geography of the earth may also have played a crucial role in setting the background <span class="hlt">oceanic</span> circulation pattern favorable to ice growth. On the other hand, the <span class="hlt">ocean</span> circulation may have changed only after the ice sheet started growing, with a similar climatic imprint. It is, therefore, still under debate what the primary forcing or trigger of this transition was. Using an <span class="hlt">ocean</span> general circulation model (POP) and two different geography reconstruc-tions for the middle-late Eocene, we find two distinctly different patterns of the <span class="hlt">oceanic</span> circulation to be possible under the same forcing. The first one features deep-water formation and warmer SSTs in the <span class="hlt">Southern</span> Pacific while in the second, deep water forms in the North Pacific <span class="hlt">Ocean</span> and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> SSTs are colder. The presence of a double equilibrium shows that the <span class="hlt">ocean</span> circulation was highly susceptible to large scale transitions during the middle-late Eocene. Additionally, changes in benthic oxygen and Neodymium isotopes depict significant changes during the same period. We suggest that a transition in the global meridional overturing circulation can explain the observed changes and preconditions the global climate for the two-step transition into an Icehouse state at the Eocene-Oligocene boundary.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018OcMod.124....1P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018OcMod.124....1P"><span>Parameterized and resolved <span class="hlt">Southern</span> <span class="hlt">Ocean</span> eddy compensation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Poulsen, Mads B.; Jochum, Markus; Nuterman, Roman</p> <p>2018-04-01</p> <p>The ability to parameterize <span class="hlt">Southern</span> <span class="hlt">Ocean</span> eddy effects in a forced coarse resolution <span class="hlt">ocean</span> general circulation model is assessed. The transient model response to a suite of different <span class="hlt">Southern</span> <span class="hlt">Ocean</span> wind stress forcing perturbations is presented and compared to identical experiments performed with the same model in 0.1° eddy-resolving resolution. With forcing of present-day wind stress magnitude and a thickness diffusivity formulated in terms of the local stratification, it is shown that the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> residual meridional overturning circulation in the two models is different in structure and magnitude. It is found that the difference in the upper overturning cell is primarily explained by an overly strong subsurface flow in the parameterized eddy-induced circulation while the difference in the lower cell is mainly ascribed to the mean-flow overturning. With a zonally constant decrease of the zonal wind stress by 50% we show that the absolute decrease in the overturning circulation is insensitive to model resolution, and that the meridional isopycnal slope is relaxed in both models. The agreement between the models is not reproduced by a 50% wind stress increase, where the high resolution overturning decreases by 20%, but increases by 100% in the coarse resolution model. It is demonstrated that this difference is explained by changes in surface buoyancy forcing due to a reduced <span class="hlt">Antarctic</span> sea ice cover, which strongly modulate the overturning response and <span class="hlt">ocean</span> stratification. We conclude that the parameterized eddies are able to mimic the transient response to altered wind stress in the high resolution model, but partly misrepresent the unperturbed <span class="hlt">Southern</span> <span class="hlt">Ocean</span> meridional overturning circulation and associated heat transports.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeoRL..40.1409H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeoRL..40.1409H"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> bottom water characteristics in CMIP5 models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Heuzé, CéLine; Heywood, Karen J.; Stevens, David P.; Ridley, Jeff K.</p> <p>2013-04-01</p> <p><span class="hlt">Southern</span> <span class="hlt">Ocean</span> deep water properties and formation processes in climate models are indicative of their capability to simulate future climate, heat and carbon uptake, and sea level rise. <span class="hlt">Southern</span> <span class="hlt">Ocean</span> temperature and density averaged over 1986-2005 from 15 CMIP5 (Coupled Model Intercomparison Project Phase 5) climate models are compared with an observed climatology, focusing on bottom water. Bottom properties are reasonably accurate for half the models. Ten models create dense water on the <span class="hlt">Antarctic</span> shelf, but it mixes with lighter water and is not exported as bottom water as in reality. Instead, most models create deep water by open <span class="hlt">ocean</span> deep convection, a process occurring rarely in reality. Models with extensive deep convection are those with strong seasonality in sea ice. Optimum bottom properties occur in models with deep convection in the Weddell and Ross Gyres. Bottom Water formation processes are poorly represented in <span class="hlt">ocean</span> models and are a key challenge for improving climate predictions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1611332V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1611332V"><span>Towards the impact of eddies on the response of the global <span class="hlt">ocean</span> circulation to <span class="hlt">Southern</span> <span class="hlt">Ocean</span> gateway opening</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Viebahn, Jan; von der Heydt, Anna S.; Dijkstra, Henk A.</p> <p>2014-05-01</p> <p>During the past 65 Million (Ma) years, Earth's climate has undergone a major change from warm 'greenhouse' to colder 'icehouse' conditions with extensive ice sheets in the polar regions of both hemispheres. The Eocene-Oligocene (~34 Ma) and Oligocene-Miocene (~23 Ma) boundaries reflect major transitions in Cenozoic global climate change. Proposed mechanisms of these transitions include reorganization of <span class="hlt">ocean</span> circulation due to critical gateway opening/deepening, changes in atmospheric CO2-concentration, and feedback mechanisms related to land-ice formation. A long-standing hypothesis is that the formation of the <span class="hlt">Antarctic</span> Circumpolar Current due to opening/deepening of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> gateways led to glaciation of the <span class="hlt">Antarctic</span> continent. However, while this hypothesis remains controversial, its assessment via coupled climate model simulations depends crucially on the spatial resolution in the <span class="hlt">ocean</span> component. More precisely, only high-resolution modeling of the turbulent <span class="hlt">ocean</span> circulation is capable of adequately describing reorganizations in the <span class="hlt">ocean</span> flow field and related changes in turbulent heat transport. In this study, for the first time results of a high-resolution (0.1° horizontally) realistic global <span class="hlt">ocean</span> model simulation with a closed Drake Passage are presented. Changes in global <span class="hlt">ocean</span> temperatures, heat transport, and <span class="hlt">ocean</span> circulation (e.g., Meridional Overturning Circulation and <span class="hlt">Antarctic</span> Coastal Current) are established by comparison with an open Drake Passage high-resolution reference simulation. Finally, corresponding low-resolution simulations are also analyzed. The results highlight the essential impact of the <span class="hlt">ocean</span> eddy field in palaeoclimatic change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://rosap.ntl.bts.gov/view/dot/18418','DOTNTL'); return false;" href="https://rosap.ntl.bts.gov/view/dot/18418"><span><span class="hlt">Antarctic</span> climate change and the environment</span></a></p> <p><a target="_blank" href="http://ntlsearch.bts.gov/tris/index.do">DOT National Transportation Integrated Search</a></p> <p></p> <p>2009-11-01</p> <p>This volume provides a comprehensive, up-to-date account of how the physical and biological : environment of the <span class="hlt">Antarctic</span> continent and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> has changed from Deep Time until : the present day. It also considers how the <span class="hlt">Antarctic</span> environmen...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=GL-2002-002282&hterms=Antarctic+icebergs&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DAntarctic%2Bicebergs','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=GL-2002-002282&hterms=Antarctic+icebergs&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DAntarctic%2Bicebergs"><span><span class="hlt">Antarctic</span> Peninsula and Weddell Sea</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>Numerous icebergs are breaking out of the sea ice in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> surrounding the <span class="hlt">Antarctic</span> Peninsula. This true-color MODIS image from November 13, 2001, shows several icebergs drifting out of the Weddell Sea. The <span class="hlt">Antarctic</span> Peninsula (left) reaches out into the Drake Passage, which separates the <span class="hlt">southern</span> tip of South America from Antarctica. Warmer temperatures have cleared a tiny patch of bare ground at the Peninsula's tip. The predominant <span class="hlt">ocean</span> current in the area is the <span class="hlt">Antarctic</span> Circumpolar Current ('circum' meaning 'around'), which is also the 'West Wind Drift.' The current is the largest permanent current in the world, and water is moved eastward by westerly winds. Icebergs leaving the Weddell Sea are likely to be moved north and east by the current. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002DSRII..49.1881P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002DSRII..49.1881P"><span>Salp/krill interactions in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>: spatial segregation and implications for the carbon flux</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pakhomov, E. A.; Froneman, P. W.; Perissinotto, R.</p> <p></p> <p>Available data on the spatial distribution and feeding ecophysiology of <span class="hlt">Antarctic</span> krill, Euphausia superba, and the tunicate, Salpa thompsoni, in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> are summarized in this study. <span class="hlt">Antarctic</span> krill and salps generally display pronounced spatial segregation at all spatial scales. This appears to be the result of a clear biotopical separation of these key species in the <span class="hlt">Antarctic</span> pelagic food web. Krill and salps are found in different water masses or water mass modifications, which are separated by primary or secondary frontal features. On the small-scale (<100 km), <span class="hlt">Antarctic</span> krill and salps are usually restricted to the specific water parcels, or are well segregated vertically. Krill and salp grazing rates estimated using the in situ gut fluorescence technique are among the highest recorded in the <span class="hlt">Antarctic</span> pelagic food web. Although krill and salps at times may remove the entire daily primary production, generally their grazing impact is moderate (⩽50% of primary production). The regional ecological consequences of years of high salp densities may be dramatic. If the warming trend, which is observed around the <span class="hlt">Antarctic</span> Peninsula and in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, continues, salps may become a more prominent player in the trophic structure of the <span class="hlt">Antarctic</span> marine ecosystem. This likely would be coupled with a dramatic decrease in krill productivity, because of a parallel decrease in the spatial extension of the krill biotope. The high <span class="hlt">Antarctic</span> regions, particularly the Marginal Ice Zone, have, however, effective physiological mechanisms that may provide protection against the salp invasion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1988ClDy....3...93C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988ClDy....3...93C"><span>Late Pleistocene variations in <span class="hlt">Antarctic</span> sea ice II: effect of interhemispheric deep-<span class="hlt">ocean</span> heat exchange</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Crowley, Thomas J.; Parkinson, Claire L.</p> <p>1988-10-01</p> <p>Variations in production rates of warm North Atlantic Deep Water (NADW) have been proposed as a mechanism for linking climate fluctuations in the northern and <span class="hlt">southern</span> hemispheres during the Pleistocene. We have tested this hypothesis by examining the sensitivity of a thermodynamic/dynamic model for <span class="hlt">Antarctic</span> sea ice to changes in vertical <span class="hlt">ocean</span> heat flux and comparing the simulations with modified CLIMAP sea-ice maps for 18 000 B.P. Results suggest that changes in NADW production rates, and the consequent changes in the vertical <span class="hlt">ocean</span> heat flux in the <span class="hlt">Antarctic</span>, can only account for about 20% 30% of the overall variance in <span class="hlt">Antarctic</span> sea-ice extent. This conclusion has been validated against an independent geological data set involving a time series of sea-surface temperatures from the subantarctic. The latter comparison suggests that, although the overall influence of NADW is relatively minor, the linkage may be much more significant at the 41 000-year obliquity period. Despite some limitations in the models and geological data, we conclude that NADW variations may have played only a modest role in causing late Pleistocene climate change in the high latitudes of the <span class="hlt">southern</span> hemisphere. Our conclusion is consistent with calculations by Manabe and Broccoli (1985) suggesting that atmospheric CO2 changes may be more important for linking the two hemispheres.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004GeoRL..31.9304L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004GeoRL..31.9304L"><span>Increased exposure of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> phytoplankton to ultraviolet radiation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lubin, Dan; Arrigo, Kevin R.; van Dijken, Gert L.</p> <p>2004-05-01</p> <p>Satellite remote sensing of both surface solar ultraviolet radiation (UVR) and chlorophyll over two decades shows that biologically significant ultraviolet radiation increases began to occur over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> three years before the ozone ``hole'' was discovered. Beginning in October 1983, the most frequent occurrences of enhanced UVR over phytoplankton-rich waters occurred in the Weddell Sea and Indian <span class="hlt">Ocean</span> sectors of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, impacting 60% of the surface biomass by the late 1990s. These results suggest two reasons why more serious impacts to the base of the marine food web may not have been detected by field experiments: (1) the onset of UVR increases several years before dedicated field work began may have impacted the most sensitive organisms long before such damage could be detected, and (2) most biological field work has so far not taken place in <span class="hlt">Antarctic</span> waters most extensively subjected to enhanced UVR.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_5 --> <div id="page_6" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="101"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1233769-de-correlation-westerly-winds-westerly-wind-stress-over-southern-ocean-during-last-glacial-maximum','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1233769-de-correlation-westerly-winds-westerly-wind-stress-over-southern-ocean-during-last-glacial-maximum"><span>The de-correlation of westerly winds and westerly-wind stress over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> during the Last Glacial Maximum</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Liu, Wei; Lu, Jian; Leung, Lai-Yung R.</p> <p>2015-02-22</p> <p>This paper investigates the changes of the <span class="hlt">Southern</span> Westerly Winds (SWW) and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (SO) upwelling between the Last Glacial Maximum (LGM) and preindustrial (PI) in the PMIP3/CMIP5 simulations, highlighting the role of the <span class="hlt">Antarctic</span> sea ice in modulating the wind stress effect on the <span class="hlt">ocean</span>. Particularly, a discrepancy may occur between the changes in SWW and westerly wind stress, caused primarily by an equatorward expansion of winter <span class="hlt">Antarctic</span> sea ice that undermines the wind stress in driving the liquid <span class="hlt">ocean</span>. Such discrepancy may reflect the LGM condition in reality, in view of that the model simulates this condition hasmore » most credible simulation of modern SWW and <span class="hlt">Antarctic</span> sea ice. The effect of wind stress on the SO upwelling is further explored via the wind-induced Ekman pumping, which is reduced under the LGM condition in all models, in part by the sea-ice “capping” effect present in the models.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMPP23A1376G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMPP23A1376G"><span>Ventilation of the deep <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and changes in atmospheric CO2 during the last deglacial and glacial periods</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gottschalk, J.; Skinner, L. C.; Lippold, J. A.; Jaccard, S.; Vogel, H.; Frank, N.; Waelbroeck, C.</p> <p>2014-12-01</p> <p>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is thought to have played a key role in atmospheric CO2 (CO2,atm) variations, both via its role in bringing carbon-rich deep-waters into contact with the atmosphere, and via its capacity for enhanced biologically mediated carbon export into the deep sea. The governing mechanisms of millennial scale rises in CO2,atm during the last deglacial and glacial periods have been linked controversially either with variations in biological export productivity, possibly driven by fluctuations in airborne dust supply, or to variations in <span class="hlt">southern</span> high-latitude vertical mixing, possibly driven by changes in westerly wind stress or density stratification across the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> water column. However, the impact of these processes on deep, <span class="hlt">southern</span> high-latitude carbon sequestration and <span class="hlt">ocean</span>-atmosphere CO2 exchange remain ambiguous. We present proxy evidence for the link between deep carbon storage in the sub-<span class="hlt">Antarctic</span> Atlantic with changes in CO2,atm during the last 70 ka from sub-millennially resolved changes in bottom water oxygenation based on the uranium accumulation in authigenic coatings on foraminiferal shells and the δ13C offset between epibenthic and infaunal foraminifera (Δδ13C). We compare our results with reconstructed opal fluxes and sediment model output data to assess the impact of physical and biological processes on <span class="hlt">Southern</span> <span class="hlt">Ocean</span> carbon storage. While variations in sub-<span class="hlt">Antarctic</span> Atlantic export production are intrinsically linked with changes in airborne dust supply supporting the major impact of dust on the biological soft-tissue pump, they cannot account for observed changes in pore water organic carbon respiration indicated by increasing Δδ13C and therefore, bottom water oxygen changes in the deep sub-<span class="hlt">Antarctic</span> Atlantic. This is in strong support of millennial-scale fluctuations in deep <span class="hlt">Southern</span> <span class="hlt">Ocean</span> carbon storage primarily controlled by the ventilation of the deep <span class="hlt">ocean</span> by <span class="hlt">southern</span>-sourced water masses, which emphasize the strong</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFMIN44A..01D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFMIN44A..01D"><span><span class="hlt">Antarctic</span> Data Management as Part of the IPY Legacy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>de Bruin, T.</p> <p>2006-12-01</p> <p>The <span class="hlt">Antarctic</span> Treaty states that "scientific observations and results from Antarctica shall be exchanged and made freely available". Antarctica includes the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. In support of this, National <span class="hlt">Antarctic</span> Data Centres (NADC) are being established to catalogue data sets and to provide information on data sets to scientists and others with interest in <span class="hlt">Antarctic</span> science. The Joint Committee on <span class="hlt">Antarctic</span> Data Management (JCADM) was established by the Scientific Committee on <span class="hlt">Antarctic</span> Research (SCAR) and the Council of Managers of National <span class="hlt">Antarctic</span> Programs (COMNAP). JCADM comprises representatives of the National <span class="hlt">Antarctic</span> Data Centres. Currently 30 nations around the world are represented in JCADM. JCADM is responsible for the <span class="hlt">Antarctic</span> Master Directory (AMD), the internationally accessible, web-based, searchable record of <span class="hlt">Antarctic</span> and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> data set descriptions. The AMD is directly integrated into the international Global Change Master Directory (GCMD) to help further merge <span class="hlt">Antarctic</span> science into global science. The AMD is a resource for scientists to advertise the data they have collected and to search for data they may need. JCADM is the <span class="hlt">Antarctic</span> component of the IPY Data Infrastructure, which is presently being developed. This presentation will give an overview of the organization of <span class="hlt">Antarctic</span> and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> data management with sections on the organizational structure of JCADM, contents of the <span class="hlt">Antarctic</span> Master Directory, relationships to the SCAR Scientific Research Programmes (SRP) and IPY, international embedding and connections with discipline-based peer organizations like the International Oceanographic Data and Information Exchange Committee (IODE). It will focus primarily on the role that an existing infrastructure as JCADM, may play in the development of the IPY Data Infrastructure and will provide considerations for IPY data management, based on the experiences in <span class="hlt">Antarctic</span> and oceanographic data management.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18513396','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18513396"><span>Bioavailable iron in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>: the significance of the iceberg conveyor belt.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Raiswell, Rob; Benning, Liane G; Tranter, Martyn; Tulaczyk, Slawek</p> <p>2008-05-30</p> <p>Productivity in the <span class="hlt">Southern</span> <span class="hlt">Oceans</span> is iron-limited, and the supply of iron dissolved from aeolian dust is believed to be the main source from outside the marine reservoir. Glacial sediment sources of iron have rarely been considered, as the iron has been assumed to be inert and non-bioavailable. This study demonstrates the presence of potentially bioavailable Fe as ferrihydrite and goethite in nanoparticulate clusters, in sediments collected from icebergs in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and glaciers on the <span class="hlt">Antarctic</span> landmass. Nanoparticles in ice can be transported by icebergs away from coastal regions in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, enabling melting to release bioavailable Fe to the open <span class="hlt">ocean</span>. The abundance of nanoparticulate iron has been measured by an ascorbate extraction. This data indicates that the fluxes of bioavailable iron supplied to the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> from aeolian dust (0.01-0.13 Tg yr(-1)) and icebergs (0.06-0.12 Tg yr(-1)) are comparable. Increases in iceberg production thus have the capacity to increase productivity and this newly identified negative feedback may help to mitigate fossil fuel emissions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PrOce.122...10B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PrOce.122...10B"><span>Productivity and linkages of the food web of the <span class="hlt">southern</span> region of the western <span class="hlt">Antarctic</span> Peninsula continental shelf</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ballerini, Tosca; Hofmann, Eileen E.; Ainley, David G.; Daly, Kendra; Marrari, Marina; Ribic, Christine A.; Smith, Walker O.; Steele, John H.</p> <p>2014-03-01</p> <p>The productivity and linkages in the food web of the <span class="hlt">southern</span> region of the west <span class="hlt">Antarctic</span> Peninsula continental shelf were investigated using a multi-trophic level mass balance model. Data collected during the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Global <span class="hlt">Ocean</span> Ecosystem Dynamics field program were combined with data from the literature on the abundance and diet composition of zooplankton, fish, seabirds and marine mammals to calculate energy flows in the food web and to infer the overall food web structure at the annual level. Sensitivity analyses investigated the effects of variability in growth and biomass of <span class="hlt">Antarctic</span> krill (Euphausia superba) and in the biomass of <span class="hlt">Antarctic</span> krill predators on the structure and energy fluxes in the food web. Scenario simulations provided insights into the potential responses of the food web to a reduced contribution of large phytoplankton (diatom) production to total primary production, and to reduced consumption of primary production by <span class="hlt">Antarctic</span> krill and mesozooplankton coincident with increased consumption by microzooplankton and salps. Model-derived estimates of primary production were 187-207 g C m-2 y-1, which are consistent with observed values (47-351 g C m-2 y-1). Simulations showed that <span class="hlt">Antarctic</span> krill provide the majority of energy needed to sustain seabird and marine mammal production, thereby exerting a bottom-up control on higher trophic level predators. Energy transfer to top predators via mesozooplanton was a less efficient pathway, and salps were a production loss pathway because little of the primary production they consumed was passed to higher trophic levels. Increased predominance of small phytoplankton (nanoflagellates and cryptophytes) reduced the production of <span class="hlt">Antarctic</span> krill and of its predators, including seabirds and seals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMGC54A..08R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMGC54A..08R"><span>The Uptake of Heat and Carbon by the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in the CMIP5 Earth System Models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Russell, J. L.; Stouffer, R. J.; Dunne, J. P.; John, J. G.</p> <p>2011-12-01</p> <p>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> surrounding the <span class="hlt">Antarctic</span> continent accounts for a disproportionate share of the heat and carbon dioxide that is removed from contact with the atmosphere into the <span class="hlt">ocean</span>. The vigorous air-sea exchange driven by the <span class="hlt">Southern</span> Hemisphere Westerlies, combined with the dearth of observations, makes the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> a major source of uncertainty in projecting the rate of warming of our atmosphere, especially considering that the vertical mixing of the <span class="hlt">ocean</span> and the corollary air-sea fluxes may be vulnerable to climate change. We assess the heat and carbon uptake by the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in future simulations by the IPCC-AR5 Earth System Models (ESMs), focusing on the GFDL simulations. Using the 1860 control simulation as our baseline, we explore the differences in heat and carbon uptake between the major "Representative Concentration Pathways" (RCPs) as simulated by the various ESMs in order to quantify the uncertainties in the climate projections related to the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> window into the deep <span class="hlt">ocean</span> reservoir.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.C34B..07A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.C34B..07A"><span>Present-day Circum-<span class="hlt">Antarctic</span> Simulations using the POPSICLES Coupled Ice Sheet-<span class="hlt">Ocean</span> Model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Asay-Davis, X.; Martin, D. F.; Price, S. F.; Maltrud, M. E.; Collins, W.</p> <p>2014-12-01</p> <p>We present POPSICLES simulation results covering the full <span class="hlt">Antarctic</span> Ice Sheet and the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> spanning the period 1990 to 2010. Simulations are performed at 0.1o (~5 km) <span class="hlt">ocean</span> resolution and with adaptive ice-sheet model resolution as fine as 500 m. We compare time-averaged melt rates below a number of major ice shelves with those reported by Rignot et al. (2013) as well as other recent studies. We also present seasonal variability and decadal trends in submarine melting from several <span class="hlt">Antarctic</span> regions. Finally, we explore the influence on basal melting and system dynamics resulting from two different choices of climate forcing: a "normal-year" climatology and the CORE v. 2 forcing data (Large and Yeager 2008).POPSICLES couples the POP2x <span class="hlt">ocean</span> model, a modified version of the Parallel <span class="hlt">Ocean</span> Program (Smith and Gent, 2002), and the BISICLES ice-sheet model (Cornford et al., 2012). POP2x includes sub-ice-shelf circulation using partial top cells (Losch, 2008) and boundary layer physics following Holland and Jenkins (1999), Jenkins (2001), and Jenkins et al. (2010). Standalone POP2x output compares well with standard ice-<span class="hlt">ocean</span> test cases (e.g., ISOMIP; Losch, 2008) and other continental-scale simulations and melt-rate observations (Kimura et al., 2013; Rignot et al., 2013). BISICLES makes use of adaptive mesh refinement and a 1st-order accurate momentum balance similar to the L1L2 model of Schoof and Hindmarsh (2009) to accurately model regions of dynamic complexity, such as ice streams, outlet glaciers, and grounding lines. Results of BISICLES simulations have compared favorably to comparable simulations with a Stokes momentum balance in both idealized tests (MISMIP-3D; Pattyn et al., 2013) and realistic configurations (Favier et al. 2014).A companion presentation, "Response of the <span class="hlt">Antarctic</span> Ice Sheet to <span class="hlt">ocean</span> forcing using the POPSICLES coupled ice sheet-<span class="hlt">ocean</span> model" in session C024 covers the ice-sheet response to these melt rates in the coupled simulation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15...64H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15...64H"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> Bottom Water Characteristics in CMIP5 Models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Heuzé, Céline; Heywood, Karen; Stevens, David; Ridley, Jeff</p> <p>2013-04-01</p> <p>The depiction of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> deep water properties and formation processes in climate models is an indicator of their capability to simulate future climate, heat and carbon uptake, and sea level rise. <span class="hlt">Southern</span> <span class="hlt">Ocean</span> potential temperature and density averaged over 1986-2005 from fifteen CMIP5 climate models are compared with an observed climatology, focusing on bottom water properties. The mean bottom properties are reasonably accurate for half of the models, but the other half may not yet have approached an equilibrium state. Eleven models create dense water on the <span class="hlt">Antarctic</span> shelf, but it does not spill off and propagate northwards, alternatively mixing rapidly with less dense water. Instead most models create deep water by open <span class="hlt">ocean</span> deep convection. Models with large deep convection areas are those with a strong seasonal cycle in sea ice. The most accurate bottom properties occur in models hosting deep convection in the Weddell and Ross gyres.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/2007/1047/srp/srp020/of2007-1047srp020.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/2007/1047/srp/srp020/of2007-1047srp020.pdf"><span><span class="hlt">Antarctic</span> ice-rafted detritus (IRD) in the South Atlantic: Indicators of iceshelf dynamics or <span class="hlt">ocean</span> surface conditions?</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Nielsen, Simon H.H.; Hodell, D.A.</p> <p>2007-01-01</p> <p><span class="hlt">Ocean</span> sediment core TN057-13PC4/ODP1094, from the Atlantic sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, contains elevated lithogenic material in sections representing the last glacial period compared to the Holocene. This ice-rafted detritus is mainly comprised of volcanic glass and ash, but has a significant input of what was previously interpreted as quartz during peak intervals (Kanfoush et al., 2000, 2002). Our analysis of these clear mineral grains indicates that most are plagioclase, and that South Sandwich Islands is the predominant source, similar to that inferred for the volcanic glass (Nielsen et al., in review). In addition, quartz and feldspar with possible <span class="hlt">Antarctic</span> origin occur in conjunction with postulated episodes of <span class="hlt">Antarctic</span> deglaciation. We conclude that while sea ice was the dominant ice rafting agent in the Polar Frontal Zone of the South Atlantic during the last glacial period, the Holocene IRD variability may reflect <span class="hlt">Antarctic</span> ice sheet dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GPC...166...62C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GPC...166...62C"><span><span class="hlt">Ocean</span> as the main driver of <span class="hlt">Antarctic</span> ice sheet retreat during the Holocene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Crosta, Xavier; Crespin, Julien; Swingedouw, Didier; Marti, Olivier; Masson-Delmotte, Valérie; Etourneau, Johan; Goosse, Hugues; Braconnot, Pascale; Yam, Ruth; Brailovski, Irena; Shemesh, Aldo</p> <p>2018-07-01</p> <p><span class="hlt">Ocean</span>-driven basal melting has been shown to be the main ablation process responsible for the recession of many <span class="hlt">Antarctic</span> ice shelves and marine-terminating glaciers over the last decades. However, much less is known about the drivers of ice shelf melt prior to the short instrumental era. Based on diatom oxygen isotope (δ18Odiatom; a proxy for glacial ice discharge in solid or liquid form) records from western <span class="hlt">Antarctic</span> Peninsula (West Antarctica) and Adélie Land (East Antarctica), higher <span class="hlt">ocean</span> temperatures were suggested to have been the main driver of enhanced ice melt during the Early-to-Mid Holocene while atmosphere temperatures were proposed to have been the main driver during the Late Holocene. Here, we present a new Holocene δ18Odiatom record from Prydz Bay, East Antarctica, also suggesting an increase in glacial ice discharge since 4500 years before present ( 4.5 kyr BP) as previously observed in <span class="hlt">Antarctic</span> Peninsula and Adélie Land. Similar results from three different regions around Antarctica thus suggest common driving mechanisms. Combining marine and ice core records along with new transient accelerated simulations from the IPSL-CM5A-LR climate model, we rule out changes in air temperatures during the last 4.5 kyr as the main driver of enhanced glacial ice discharge. Conversely, our simulations evidence the potential for significant warmer subsurface waters in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> during the last 6 kyr in response to enhanced summer insolation south of 60°S and enhanced upwelling of Circumpolar Deep Water towards the <span class="hlt">Antarctic</span> shelf. We conclude that ice front and basal melting may have played a dominant role in glacial discharge during the Late Holocene.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002cosp...34E1901V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002cosp...34E1901V"><span>Observations of frozen skin of <span class="hlt">southern</span> <span class="hlt">ocean</span> from multifrequency scanning microwave radiometer (MSMR) onboard oceansat - 1</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vyas, N.; Bhandari, S.; Dash, M.; Pandey, P.; Khare, N.</p> <p></p> <p>Encircling the <span class="hlt">Antarctic</span>, <span class="hlt">Southern</span> <span class="hlt">Ocean</span> connects all the three <span class="hlt">oceans</span> of the world with fastest current system found anywhere in the world. The region is thermally very stable and is covered with ice, which has a strong seasonal variability. The sea ice pulsates annually with seasonal migration varying from 4 million square kilometer to 20 million square kilometer during summer and winter respectively. This has strong influence on energy balance of the <span class="hlt">ocean</span>-ice-atmosphere system, and hence on atmospheric general circulation affecting weather and climate. Sea ice also works as an insulator thus inhibiting the energy flux between <span class="hlt">ocean</span> and atmosphere. It also influences the ecosystem of the <span class="hlt">southern</span> <span class="hlt">ocean</span>, which has rich fish resources with global economic values such as krill and tooth fish. During winter Krill survives on algae found at the under side of the sea ice. The <span class="hlt">southern</span> <span class="hlt">ocean</span> is known to have high nutrition but low concentration of chlorophyll-a, which is a proxy of the phytoplankton. It is now understood that iron is the limiting factor as has been shown by various iron fertilization experiments. Passive microwave radiometry from space has been extensively used for the study of sea ice types and concentration in the Arctic and the <span class="hlt">Antarctic</span> regions. Since late 1970s, data from SMMR and SSM/I have been used to study trends in sea ice extent and area. We have further extended the above studies by using data from OCEANSAT - 1 MSMR. The data, acquired at 18 GHz (H) with 50 kilometer resolution and having a swath of 1360 kilometer and a repeat cycle of 2 days, was processed to generate the brightness temperature maps over the Antarctica for a period of 2 years and the results were analyzed in conjunction with those obtained earlier (since 1978) through the study of SMMR and SSM/I data. Besides strong seasonal variability, our analysis shows an increasing trend in the sea ice extent during the recent years and the rate appears to be accelerating contrary to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMGC13C0651M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMGC13C0651M"><span>Atmospheric and <span class="hlt">Oceanic</span> Response to <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Deep Convection Oscillations on Decadal to Centennial Time Scales in Climate Models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martin, T.; Reintges, A.; Park, W.; Latif, M.</p> <p>2014-12-01</p> <p>Many current coupled global climate models simulate open <span class="hlt">ocean</span> deep convection in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> as a recurring event with time scales ranging from a few years to centennial (de Lavergne et al., 2014, Nat. Clim. Ch.). The only observation of such event, however, was the occurrence of the Weddell Polynya in the mid-1970s, an open water area of 350 000 km2 within the <span class="hlt">Antarctic</span> sea ice in three consecutive winters. Both the wide range of modeled frequency of occurrence and the absence of deep convection in the Weddell Sea highlights the lack of understanding concerning the phenomenon. Nevertheless, simulations indicate that atmospheric and <span class="hlt">oceanic</span> responses to the cessation of deep convection in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> include a strengthening of the low-level atmospheric circulation over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (increasing SAM index) and a reduction in the export of <span class="hlt">Antarctic</span> Bottom Water (AABW), potentially masking the regional effects of global warming (Latif et al., 2013, J. Clim.; Martin et al., 2014, Deep Sea Res. II). It is thus of great importance to enhance our understanding of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> deep convection and clarify the associated time scales. In two multi-millennial simulations with the Kiel Climate Model (KCM, ECHAM5 T31 atmosphere & NEMO-LIM2 ~2˚ <span class="hlt">ocean</span>) we showed that the deep convection is driven by strong <span class="hlt">oceanic</span> warming at mid-depth periodically overriding the stabilizing effects of precipitation and ice melt (Martin et al., 2013, Clim. Dyn.). Sea ice thickness also affects location and duration of the deep convection. A new control simulation, in which, amongst others, the atmosphere grid resolution is changed to T42 (~2.8˚), yields a faster deep convection flip-flop with a period of 80-100 years and a weaker but still significant global climate response similar to CMIP5 simulations. While model physics seem to affect the time scale and intensity of the phenomenon, the driving mechanism is a rather robust feature. Finally, we compare the atmospheric and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004DSRII..51.1551M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004DSRII..51.1551M"><span>Russian deep-sea investigations of <span class="hlt">Antarctic</span> fauna</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Malyutina, Marina</p> <p>2004-07-01</p> <p>A review of the Russian deep-sea investigation of <span class="hlt">Antarctic</span> fauna beginning from the first scientific collection of Soviet whaling fleet expeditions 1946-1952 is presented. The paper deals with the following expeditions, their main tasks and results. These expeditions include three cruises of research vessel (R.V.) Ob in the Indian sector of the <span class="hlt">Antarctic</span> and in the <span class="hlt">Southern</span> Pacific (1955-1958); 11 cruises of the R.V. Akademik Kurchatov in the <span class="hlt">southern</span> Atlantic (November-December 1971); 16 cruises of the R.V. Dmitriy Mendeleev in the Australia-New Zealand area and adjacent water of the <span class="hlt">Antarctic</span> (December 1975-March 1976); 43 cruises of the R.V. Akademik Kurchatov in the <span class="hlt">southern</span> Atlantic (October 1985-February 1986); and 43 cruises of the R.V. Dmitriy Mendeleev in the Atlantic sector of the South <span class="hlt">Ocean</span> (January-May 1989). A list of the main publications on the benthic taxa collected during these expeditions with data of their distribution is presented. The results of Russian explorations of the <span class="hlt">Antarctic</span> fauna are presented as theoretical conclusions in the following topics: (1) Vertical zonation in the distribution of the <span class="hlt">Antarctic</span> deep-sea fauna; (2) Biogeographic division of the abyssal and hadal zones; (3) Origin of the <span class="hlt">Antarctic</span> deep-sea fauna; (4) Distributional pathways of the <span class="hlt">Antarctic</span> abyssal fauna through the World <span class="hlt">Ocean</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMPP22B..05G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMPP22B..05G"><span>A Stratification Boomerang: Nonlinear Dependence of Deep <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Ventilation on PCO2</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Galbraith, E. D.; Merlis, T. M.</p> <p>2014-12-01</p> <p>Strong correlations between atmospheric CO2, <span class="hlt">Antarctic</span> temperatures, and marine proxy records have hinted that ventilation of the deep <span class="hlt">Southern</span> <span class="hlt">Ocean</span> may have played a central role in the variations of CO2 over glacial-interglacial cycles. One proposition is that, in general, the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ventilates the deep more strongly under higher CO2, due to a change in winds and/or the dominance of thermal stratification in a warm <span class="hlt">ocean</span>, which weakens <span class="hlt">ocean</span> biological carbon storage. Here, we explore this idea with a suite of multi-millennial simulations using the GFDL CM2Mc global coupled model. The results are, indeed, consistent with increasing ventilation of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> as pCO2 increases above modern. However, they reveal a surprising twist under low pCO2: increased salinity of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, due in part to weakening atmospheric moisture transport, actually increases ventilation rate of the deep <span class="hlt">ocean</span> under low pCO2 as well. This implies that a nadir of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ventilation occurs at intermediate pCO2, which the model estimates as being close to that of the present-day. This is at odds with the interpretation that weak ventilation of the deep <span class="hlt">Southern</span> <span class="hlt">Ocean</span> was the unifying coupled mechanism for the glacial pCO2 cycles. Rather, it suggests that factors other than the ventilation rate of the deep <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, such as iron fertilization, ecosystem changes, water mass distributions, and sea ice cover, were key players in the glacial-interglacial CO2 changes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA.....5938M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA.....5938M"><span>Indian-<span class="hlt">Southern</span> <span class="hlt">Ocean</span> Latitudinal Transect (ISOLAT): A proposal for the recovery of high-resolution sedimentary records in the western Indian <span class="hlt">Ocean</span> sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mackensen, A.; Zahn, R.; Hall, I.; Kuhn, G.; Koc, N.; Francois, R.; Hemming, S.; Goldstein, S.; Rogers, J.; Ehrmann, W.</p> <p>2003-04-01</p> <p>Quantifying <span class="hlt">oceanic</span> variability at timescales of <span class="hlt">oceanic</span>, atmospheric, and cryospheric processes are the fundamental objectives of the international IMAGES program. In this context the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> plays a leading role in that it is involved, through its influence on global <span class="hlt">ocean</span> circulation and carbon budget, with the development and maintenance of the Earth's climate system. The seas surrounding Antarctica contain the world's only zonal circum-global current system that entrains water masses from the three main <span class="hlt">ocean</span> basins, and maintains the thermal isolation of Antarctica from warmer surface waters to the north. Furthermore, the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is a major site of bottom and intermediate water formation and thus actively impacts the global thermohaline circulation (THC). This proposal is an outcome of the IMAGES <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Working Group and constitutes one component of a suite of new IMAGES/IODP initiatives that aim at resolving past variability of the <span class="hlt">Antarctic</span> Circumpolar Current (ACC) on orbital and sub-orbital timescales and its involvement with rapid global <span class="hlt">ocean</span> variability and climate instability. The primary aim of this proposal is to determine millennial- to sub-centennial scale variability of the ACC and the ensuing Atlantic-Indian water transports, including surface transports and deep-water flow. We will focus on periods of rapid <span class="hlt">ocean</span> and climate change and assess the role of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in these changes, both in terms of its thermohaline circulation and biogeochemical inventories. We propose a suite of 11 sites that form a latitudinal transect across the ACC in the westernmost Indian <span class="hlt">Ocean</span> sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. The transect is designed to allow the reconstruction of ACC variability across a range of latitudes in conjunction with meridional shifts of the surface <span class="hlt">ocean</span> fronts. The northernmost reaches of the transect extend into the Agulhas Current and its retroflection system which is a key component of the THC warm water return</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.T33G..03L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.T33G..03L"><span>Hydrothermal and Chemosynthetic Ecosystems in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>: Current Knowledge on their Biology Paper 217790</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Linse, K.; Rogers, A. D.; Bohrmann, G.; Copley, J.; Tyler, P. A.</p> <p>2017-12-01</p> <p>The existence of hydrothermal and other chemosynthetic ecosystems is not surprising in the <span class="hlt">Antarctic</span>, with its active volcanoes, mid-<span class="hlt">ocean</span> ridges and back-arc basins, and abundance of marine mammals. In the last two decades a variety of active chemosynthetic ecosystems have been discovered in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, including low- and high-temperature hydrothermal vents, methane seeps, and whalefalls. Here a summary of the data from the known chemosynthetic communites will be presented, comparing the faunas of vent sites in the Bransfield Strait with those of the East Scotia Ridge (ESR) and the South Sandwich Arc, assessing the fauna at the South Georgia methane seep sites, and discussing the fauna on <span class="hlt">Antarctic</span> whale falls. As the faunal assemblages of the ESR vents are the most studied in detail to date, this talk therefore focusses on the diversity and composition of the ESR macrofaunal assemblages, their foodweb structure and microdistributions in relation to fluid chemistry and microbiology, and their phylogenetic and biogeographic relationships. The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> drives the global <span class="hlt">ocean</span> conveyor belt, and is suggested to be the centre of origin for global deep-sea fauna, as well as a region of high deep-sea species diversity. In the context of chemosynthetic environments, it may provide a gateway connecting the global vent and seep systems. The mostly endemic species of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> vent macrofauna show links to either one or more <span class="hlt">oceans</span> (Atlantic, Indian, and Pacific), with some evidence for circum-<span class="hlt">Antarctic</span> connection. The ESR species Gigantopelta chessoia, Kiwa tyleri and Vulcanolepas scotiaensis have their closest known relatives at the Longqi Vent Field on the Southwest Indian Ridge (SWIR), and one species of polynoid polychaete is known from ESR and SWIR vents. Meanwhile, Lepetdrilus sp. and a vesiocomyid clam are linked with species in the Atlantic vent fields. The stichasterid Paulasterias tyleri, the polychaete Rarricirrus jennae and the anthozoan</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1610000A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1610000A"><span>Simulations of <span class="hlt">Antarctic</span> ice shelves and the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in the POP2x <span class="hlt">ocean</span> model coupled with the BISICLES ice-sheet model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Asay-Davis, Xylar; Martin, Daniel; Price, Stephen; Maltrud, Mathew</p> <p>2014-05-01</p> <p>We present initial results from <span class="hlt">Antarctic</span>, ice-<span class="hlt">ocean</span> coupled simulations using large-scale <span class="hlt">ocean</span> circulation and ice-sheet evolution models. This presentation focuses on the <span class="hlt">ocean</span> model, POP2x, which is a modified version of POP, a fully eddying, global-scale <span class="hlt">ocean</span> model (Smith and Gent, 2002). POP2x allows for circulation beneath ice shelf cavities using the method of partial top cells (Losch, 2008). Boundary layer physics, which control fresh water and salt exchange at the ice-<span class="hlt">ocean</span> interface, are implemented following Holland and Jenkins (1999), Jenkins (2001), and Jenkins et al. (2010). Standalone POP2x output compares well with standard ice-<span class="hlt">ocean</span> test cases (e.g., ISOMIP; Losch, 2008) and other continental-scale simulations and melt-rate observations (Kimura et al., 2013; Rignot et al., 2013) and with results from other idealized ice-<span class="hlt">ocean</span> coupling test cases (e.g., Goldberg et al., 2012). A companion presentation, 'Fully resolved whole-continent Antarctica simulations using the BISICLES AMR ice sheet model coupled with the POP2x <span class="hlt">Ocean</span> Model', concentrates more on the ice-sheet model, BISICLES (Cornford et al., 2012), which includes a 1st-order accurate momentum balance (L1L2) and uses block structured, adaptive-mesh refinement to more accurately model regions of dynamic complexity, such as ice streams, outlet glaciers, and grounding lines. For idealized test cases focused on marine-ice sheet dynamics, BISICLES output compares very favorably relative to simulations based on the full, nonlinear Stokes momentum balance (MISMIP-3d; Pattyn et al., 2013). Here, we present large-scale (<span class="hlt">Southern</span> <span class="hlt">Ocean</span>) simulations using POP2x at 0.1 degree resolution with fixed ice shelf geometries, which are used to obtain and validate modeled submarine melt rates against observations. These melt rates are, in turn, used to force evolution of the BISICLES model. An offline-coupling scheme, which we compare with the ice-<span class="hlt">ocean</span> coupling work of Goldberg et al. (2012), is then used to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70187418','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70187418"><span>Productivity and linkages of the food web of the <span class="hlt">southern</span> region of the western <span class="hlt">Antarctic</span> Peninsula continental shelf</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ballerini, Tosca; Hofmann, Eileen E.; Ainley, David G.; Daly, Kendra L.; Marrari, Marina; Ribic, Christine A.; Smith, Walker O.; Steele, John H.</p> <p>2014-01-01</p> <p>The productivity and linkages in the food web of the <span class="hlt">southern</span> region of the west <span class="hlt">Antarctic</span> Peninsula continental shelf were investigated using a multi-trophic level mass balance model. Data collected during the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Global <span class="hlt">Ocean</span> Ecosystem Dynamics field program were combined with data from the literature on the abundance and diet composition of zooplankton, fish, seabirds and marine mammals to calculate energy flows in the food web and to infer the overall food web structure at the annual level. Sensitivity analyses investigated the effects of variability in growth and biomass of <span class="hlt">Antarctic</span> krill (Euphausia superba) and in the biomass of <span class="hlt">Antarctic</span> krill predators on the structure and energy fluxes in the food web. Scenario simulations provided insights into the potential responses of the food web to a reduced contribution of large phytoplankton (diatom) production to total primary production, and to reduced consumption of primary production by <span class="hlt">Antarctic</span> krill and mesozooplankton coincident with increased consumption by microzooplankton and salps. Model-derived estimates of primary production were 187–207 g C m−2 y−1, which are consistent with observed values (47–351 g C m−2 y−1). Simulations showed that <span class="hlt">Antarctic</span> krill provide the majority of energy needed to sustain seabird and marine mammal production, thereby exerting a bottom-up control on higher trophic level predators. Energy transfer to top predators via mesozooplanton was a less efficient pathway, and salps were a production loss pathway because little of the primary production they consumed was passed to higher trophic levels. Increased predominance of small phytoplankton (nanoflagellates and cryptophytes) reduced the production of <span class="hlt">Antarctic</span> krill and of its predators, including seabirds and seals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeoRL..40.3111A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeoRL..40.3111A"><span>The International Bathymetric Chart of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (IBCSO) Version 1.0 - A new bathymetric compilation covering circum-<span class="hlt">Antarctic</span> waters</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arndt, Jan Erik; Schenke, Hans Werner; Jakobsson, Martin; Nitsche, Frank O.; Buys, Gwen; Goleby, Bruce; Rebesco, Michele; Bohoyo, Fernando; Hong, Jongkuk; Black, Jenny; Greku, Rudolf; Udintsev, Gleb; Barrios, Felipe; Reynoso-Peralta, Walter; Taisei, Morishita; Wigley, Rochelle</p> <p>2013-06-01</p> <p>International Bathymetric Chart of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (IBCSO) Version 1.0 is a new digital bathymetric model (DBM) portraying the seafloor of the circum-<span class="hlt">Antarctic</span> waters south of 60°S. IBCSO is a regional mapping project of the General Bathymetric Chart of the <span class="hlt">Oceans</span> (GEBCO). The IBCSO Version 1.0 DBM has been compiled from all available bathymetric data collectively gathered by more than 30 institutions from 15 countries. These data include multibeam and single-beam echo soundings, digitized depths from nautical charts, regional bathymetric gridded compilations, and predicted bathymetry. Specific gridding techniques were applied to compile the DBM from the bathymetric data of different origin, spatial distribution, resolution, and quality. The IBCSO Version 1.0 DBM has a resolution of 500 × 500 m, based on a polar stereographic projection, and is publicly available together with a digital chart for printing from the project website (www.ibcso.org) and at <accessionId ref="info:doi/10.1594/PANGAEA.805736">http://dx.doi.org/10.1594/PANGAEA.805736</accessionId>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29674908','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29674908"><span><span class="hlt">Antarctic</span> and Sub-<span class="hlt">Antarctic</span> Asteroidea database.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Moreau, Camille; Mah, Christopher; Agüera, Antonio; Améziane, Nadia; David Barnes; Crokaert, Guillaume; Eléaume, Marc; Griffiths, Huw; Charlène Guillaumot; Hemery, Lenaïg G; Jażdżewska, Anna; Quentin Jossart; Vladimir Laptikhovsky; Linse, Katrin; Neill, Kate; Sands, Chester; Thomas Saucède; Schiaparelli, Stefano; Siciński, Jacek; Vasset, Noémie; Bruno Danis</p> <p>2018-01-01</p> <p>The present dataset is a compilation of georeferenced occurrences of asteroids (Echinodermata: Asteroidea) in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Occurrence data south of 45°S latitude were mined from various sources together with information regarding the taxonomy, the sampling source and sampling sites when available. Records from 1872 to 2016 were thoroughly checked to ensure the quality of a dataset that reaches a total of 13,840 occurrences from 4,580 unique sampling events. Information regarding the reproductive strategy (brooders vs. broadcasters) of 63 species is also made available. This dataset represents the most exhaustive occurrence database on <span class="hlt">Antarctic</span> and Sub-<span class="hlt">Antarctic</span> asteroids.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_6 --> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003PrOce..58..263H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003PrOce..58..263H"><span>Development of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Continuous Plankton Recorder survey [review article</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hosie, G. W.; Fukuchi, M.; Kawaguchi, S.</p> <p>2003-08-01</p> <p>The Continuous Plankton Recorder (CPR) Type I was first used in <span class="hlt">Antarctic</span> waters during the 1925-1927 Discovery Expedition, and has been used successfully for 70 years to monitor plankton in the North Sea and North Atlantic <span class="hlt">Ocean</span>. Sixty-five years later the CPR as a Type II version returned to <span class="hlt">Antarctic</span> waters when the Australian <span class="hlt">Antarctic</span> Division initiated a survey of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> on RSV Aurora Australis south of Australia and west to Mawson. The objectives are to study regional, seasonal, interannual and long-term variability in zooplankton abundance, species composition and community patterns, as well as the annual abundance and distribution of krill larvae. The survey covers a large area from 60°E to 160°E, and south from about 48°S to the <span class="hlt">Antarctic</span> coast-an area of more than 14 million km 2. Tows are conducted throughout the shipping season, normally September to April, but occasionally as early as July (midwinter). The large areal and temporal scale means that it is difficult to separate temporal and geographical variation in the data. Hence, CPRs are now also towed on the Japanese icebreaker Shirase in collaboration with the Japanese <span class="hlt">Antarctic</span> programme. Shirase has a fixed route and time schedule, travelling south on 110°E in early December and north on 150°E in mid-March each year, and will serve as an important temporal reference for measuring long-term interannual variability and to help interpret the Australian data. Since 1991, over 90 tows have been made, providing over 36,000 nautical miles of records. The most successful seasons to date have been the 1997/1998, 1999/2000 and 2000/2001 austral summers with 20, 31 and 26 tows, respectively. The 1999/2000 season included a unique, nearly simultaneous three-ship crossing of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> along 25° 30’E, 110°E and 157°E. Typical CPR tows show very high abundance of zooplankton in the uppermost 20 m of the permanently open <span class="hlt">ocean</span> zone between the sea-ice zone and the Sub-<span class="hlt">Antarctic</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A21Q..07S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A21Q..07S"><span>Does coupled <span class="hlt">ocean</span> enhance ozone-hole-induced <span class="hlt">Southern</span> Hemisphere circulation changes?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Son, S. W.; Han, B. R.; Kim, S. Y.; Park, R.</p> <p>2017-12-01</p> <p>The ozone-hole-induced <span class="hlt">Southern</span> Hemisphere (SH) circulation changes, such as poleward shift of westerly jet and Hadley cell widening, have been typically explored with either coupled general circulation models (CGCMs) prescribing stratospheric ozone or chemistry-climate models (CCMs) prescribing surface boundary conditions. Only few studies have utilized <span class="hlt">ocean</span>-coupled CCMs with a relatively coarse resolution. To better quantify the role of interactive chemistry and coupled <span class="hlt">ocean</span> in the ozone-hole-induced SH circulation changes, the present study examines a set of CGCM and CCM simulations archived for the Coupled Model Intercomparison Project phase 5 (CMIP5) and CCM initiative (CCMI). Although inter-model spread of <span class="hlt">Antarctic</span> ozone depletion is substantially large especially in the austral spring, both CGCMs with relatively simple ozone chemistry and CCMs with fully interactive comprehensive chemistry reasonably well reproduce long-term trends of <span class="hlt">Antarctic</span> ozone and the associated polar-stratospheric temperature changes. Most models reproduce a poleward shift of SH jet and Hadley-cell widening in the austral summer in the late 20th century as identified in reanalysis datasets. These changes are quasi-linearly related with <span class="hlt">Antarctic</span> ozone changes, confirming the critical role of <span class="hlt">Antarctic</span> ozone depletion in the austral-summer zonal-mean circulation changes. The CGCMs with simple but still interactive ozone show slightly stronger circulation changes than those with prescribed ozone. However, the long-term circulation changes in CCMs are largely insensitive to the coupled <span class="hlt">ocean</span>. While a few models show the enhanced circulation changes when <span class="hlt">ocean</span> is coupled, others show essentially no changes or even weakened circulation changes. This result suggests that the ozone-hole-related stratosphere-troposphere coupling in the late 20th century may be only weakly sensitive to the coupled <span class="hlt">ocean</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhDT.........2G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhDT.........2G"><span><span class="hlt">Oceanic</span> Controls of North American East Coast Sea Level Rise and <span class="hlt">Ocean</span> Warming of the <span class="hlt">Antarctic</span> Shelf</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goddard, Paul</p> <p></p> <p>Sea level rise (SLR) threatens coastal communities, infrastructure, and ecosystems. Worldwide, stakeholders critically depend on SLR projections with the associated uncertainty for risk assessments, decision-making and coastal planning. Recent research suggests that the <span class="hlt">Antarctic</span> ice sheet mass loss during the 21st century may contribute up to an additional one meter of global SLR by year 2100. While uncertainty still exists, this value would double the 'likely' (> 66% probability) range of global SLR (0.52-0.98 m) by the year 2100, as found by Chapter 13 on Sea Level Change in the Fifth Assessment Report by the Intergovernmental Panel on Climate Change. Here, we present three studies that assess mechanisms relevant to 21st century local, regional, and global SLR. Appendix A examines the effect of large-scale <span class="hlt">oceanic</span> and atmospheric circulation variability on extreme sea levels along the East Coast of North America. Appendices B and C analyze <span class="hlt">ocean</span> warming on the <span class="hlt">Antarctic</span> shelf and its implications for future ice shelf basal melt and <span class="hlt">Antarctic</span> Ice Sheet mass loss. These studies will contribute to more accurate projections of local, regional, and global SLR. In Appendix A, we analyze long-term tide gauge records from the North American eastern seaboard and find an extreme SLR event during 2009-2010. Within this two-year period, coastal sea levels spiked between Montauk, New York and <span class="hlt">Southern</span> Canada by up to 128 mm. This two-year spike is unprecedented in the tide gauge record and found to be a 1-in-850 year event. We show that a 30% reduction in strength of the Atlantic meridional overturning circulation (AMOC) and a strong negative North Atlantic Oscillation (NAO) index caused the extreme SLR event. Climate models project that the AMOC will weaken and NAO variability will remain high over the 21st century. Consequently, extreme SLR events on the Northeast Coast could become more frequent during the 21st century in response to climate change and SLR. In Appendix B</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22687748-latitudinal-exposure-ddts-hcb-pcbs-pbdes-dp-giant-petrels-macronectes-spp-across-southern-ocean','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22687748-latitudinal-exposure-ddts-hcb-pcbs-pbdes-dp-giant-petrels-macronectes-spp-across-southern-ocean"><span>Latitudinal exposure to DDTs, HCB, PCBs, PBDEs and DP in giant petrels (Macronectes spp.) across the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Roscales, Jose L., E-mail: jlroscales@iqog.csic.es; González-Solís, Jacob; Zango, Laura</p> <p></p> <p>Studies on Persistent Organic Pollutants (POPs) in <span class="hlt">Antarctic</span> wildlife are scarce, and usually limited to a single locality. As a result, wildlife exposure to POPs across the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is poorly understood. In this study, we report the differential exposure of the major <span class="hlt">southern</span> <span class="hlt">ocean</span> scavengers, the giant petrels, to POPs across a wide latitudinal gradient. Selected POPs (PCBs, HCB, DDTs, PBDEs) and related compounds, such as Dechlorane Plus (DP), were analyzed in plasma of <span class="hlt">southern</span> giant petrels (Macronectes giganteus) breeding on Livingston (62°S 61°W, Antarctica), Marion (46°S 37°E, sub-<span class="hlt">Antarctic</span>), and Gough (40°S 10°W, cool temperate) islands. Northern giant petrelsmore » (Macronectes halli) from Marion Island were also studied. Stable isotope ratios of C and N (δ{sup 13}C and δ{sup 15}N) were used as dietary tracers of the marine habitat and trophic level, respectively. Breeding locality was a major factor explaining petrel exposure to POPs compared with species and sex. Significant relationships between δ{sup 13}C values and POP burdens, at both inter- and intra-population levels, support latitudinal variations in feeding grounds as a key factor in explaining petrel pollutant burdens. Overall, pollutant levels in giant petrels decreased significantly with latitude, but the relative abundance (%) of the more volatile POPs increased towards Antarctica. DP was found at negligible levels compared with legacy POPs in <span class="hlt">Antarctic</span> seabirds. Spatial POP patterns found in giant petrels match those predicted by global distribution models, and reinforce the hypothesis of atmospheric long-range transport as the main source of POPs in Antarctica. Our results confirm that wildlife movements out of the polar region markedly increase their exposure to POPs. Therefore, strategies for <span class="hlt">Antarctic</span> wildlife conservation should consider spatial heterogeneity in exposure to marine pollution. Of particular relevance is the need to clarify the exposure of <span class="hlt">Antarctic</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JOUC...11..118L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JOUC...11..118L"><span>Statistical characteristics of austral summer cyclones in <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Na; Fu, Gang; Kuo, Ying-Hwa</p> <p>2012-06-01</p> <p>Characteristics of cyclones and explosively developing cyclones (or `bombs') over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in austral summer (December, January and February) from 2004 to 2008 are analyzed by using the Final Analysis (FNL) data produced by the National Centers for Environmental Prediction (NCEP) of the United States. Statistical results show that both cyclones and explosively developing cyclones frequently develop in January, and most of them occur within the latitudinal zone between 55°S and 70°S. These cyclones gradually approach the <span class="hlt">Antarctic</span> Continent from December to February. Generally cyclones and bombs move east-southeastward with some exceptions of northeastward movement. The lifetime of cyclones is around 2-6 d, and the horizontal scale is about 1000 km. Explosive cyclones have the lifetime of about 1 week with the horizontal scale reaching up to 3000 km. Compared with cyclones developed in the Northern Hemisphere, cyclones over the <span class="hlt">southern</span> <span class="hlt">ocean</span> have much higher occurrence frequency, lower central pressure and larger horizontal scale, which may be caused by the unique geographical features of the <span class="hlt">Southern</span> Hemisphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27940333','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27940333"><span>Marked phylogeographic structure of Gentoo penguin reveals an ongoing diversification process along the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vianna, Juliana A; Noll, Daly; Dantas, Gisele P M; Petry, Maria Virginia; Barbosa, Andrés; González-Acuña, Daniel; Le Bohec, Céline; Bonadonna, Francesco; Poulin, Elie</p> <p>2017-02-01</p> <p>Two main hypotheses have been debated about the biogeography of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>: (1) the <span class="hlt">Antarctic</span> Polar Front (APF), acting as a barrier between <span class="hlt">Antarctic</span> and sub-<span class="hlt">Antarctic</span> provinces, and (2) the <span class="hlt">Antarctic</span> Circumpolar Current (ACC), promoting gene flow among sub-<span class="hlt">Antarctic</span> areas. The Gentoo penguin is distributed throughout these two provinces, separated by the APF. We analyzed mtDNA (HVR1) and 12 microsatellite loci of 264 Gentoo penguins, Pygoscelis papua, from 12 colonies spanning from the Western <span class="hlt">Antarctic</span> Peninsula and the South Shetland Islands (WAP) to the sub-<span class="hlt">Antarctic</span> Islands (SAI). While low genetic structure was detected among WAP colonies (mtDNA Ф ST =0.037-0.133; microsatellite F ST =0.009-0.063), high differentiation was found between all SAI and WAP populations (mtDNA Ф ST =0.678-0.930; microsatellite F ST =0.110-0.290). These results suggest that contemporary dispersal around the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is very limited or absent. As predicted, the APF appears to be a significant biogeographical boundary for Gentoo penguin populations; however, the ACC does not promote connectivity in this species. Our data suggest demographic expansion in the WAP during the last glacial maximum (LGM, about 20kya), but stability in SAI. Phylogenetic analyses showed a deep divergence between populations from the WAP and those from the SAI. Therefore, taxonomy should be further revised. The Crozet Islands resulted as a basal clade (3.57Mya), followed by the Kerguelen Islands (2.32Mya) as well as a more recent divergence between the Falkland/Malvinas Islands and the WAP (1.27Mya). Historical isolation, local adaptation, and past climate scenarios of those Evolutionarily Significant Units may have led to different potentials to respond to climate changes. Copyright © 2016 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1616490B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1616490B"><span>The oceanographic and climatic evolution of the Paleogene <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (Arne Richter Award for Outstanding Young Scientists Lecture)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bijl, Peter; Houben, Alexander J. P.</p> <p>2014-05-01</p> <p>Continental-scale ice sheets first appeared in Antarctica following long-term cooling through the Eocene Epoch (56-34 Ma) within the Paleogene Period (65.5-23 Ma). Both the long-term cooling following early Eocene hothouse climates and the onset of large-scale glaciation itself has been related to the gradual decline of atmospheric greenhouse gas concentrations. Although much work is now centered in improving techniques for reconstructing past atmospheric pCO2, at present proxy-based reconstructions of atmospheric greenhouse gases for the Paleogene are of low temporal resolution and subject to a large degree of uncertainty. Furthermore, long-term mid-Eocene surface water cooling appears to have been confined to high- and mid-latitudes only, with little to no cooling in the tropical regions. This observation questions the role of atmospheric greenhouse gas (notably CO2) decline as a primary cause of Eocene climate cooling. Furthermore, the greenhouse-gas hypothesis has now superceded long-held hypothesis that the opening of <span class="hlt">southern</span> <span class="hlt">ocean</span> tectonic gateways cooled Antarctica. A direct relationship between the deepening of the Tasmanian Gateway and <span class="hlt">Antarctic</span> glaciation has been refuted by accurate dating of this tectonic event, indicating that the Tasmanian Gateway deepened 2 million years prior to <span class="hlt">Antarctic</span> glaciation. However, the precise secondary role of gateway evolution on <span class="hlt">Antarctic</span> climate change is not well constrained. On the other hand, it is increasingly apparent that the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> was the main region for intermediate-deep water formation in the Paleogene, which implies that even environmental change with regional effects may have had direct implications for global climate change. While the forcing mechanism that pushed Antarctica towards fully glaciated conditions is likely atmospheric pCO2 decline across a critical threshold, the regional environmental responses are not well constrained. Numerical modeling studies suggest that in conjunction with the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27828976','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27828976"><span>Seasonal and Diel Vocalization Patterns of <span class="hlt">Antarctic</span> Blue Whale (Balaenoptera musculus intermedia) in the <span class="hlt">Southern</span> Indian <span class="hlt">Ocean</span>: A Multi-Year and Multi-Site Study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Leroy, Emmanuelle C; Samaran, Flore; Bonnel, Julien; Royer, Jean-Yves</p> <p>2016-01-01</p> <p>Passive acoustic monitoring is an efficient way to provide insights on the ecology of large whales. This approach allows for long-term and species-specific monitoring over large areas. In this study, we examined six years (2010 to 2015) of continuous acoustic recordings at up to seven different locations in the Central and <span class="hlt">Southern</span> Indian Basin to assess the peak periods of presence, seasonality and migration movements of <span class="hlt">Antarctic</span> blue whales (Balaenoptera musculus intermedia). An automated method is used to detect the <span class="hlt">Antarctic</span> blue whale stereotyped call, known as Z-call. Detection results are analyzed in terms of distribution, seasonal presence and diel pattern of emission at each site. Z-calls are detected year-round at each site, except for one located in the equatorial Indian <span class="hlt">Ocean</span>, and display highly seasonal distribution. This seasonality is stable across years for every site, but varies between sites. Z-calls are mainly detected during autumn and spring at the subantarctic locations, suggesting that these sites are on the <span class="hlt">Antarctic</span> blue whale migration routes, and mostly during winter at the subtropical sites. In addition to these seasonal trends, there is a significant diel pattern in Z-call emission, with more Z-calls in daytime than in nighttime. This diel pattern may be related to the blue whale feeding ecology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980021232','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980021232"><span>Sea Ice on the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jacobs, Stanley S.</p> <p>1998-01-01</p> <p>Year-round satellite records of sea ice distribution now extend over more than two decades, providing a valuable tool to investigate related characteristics and circulations in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. We have studied a variety of features indicative of <span class="hlt">oceanic</span> and atmospheric interactions with <span class="hlt">Antarctic</span> sea ice. In the Amundsen & Bellingshausen Seas, sea ice extent was found to have decreased by approximately 20% from 1973 through the early 1990's. This change coincided with and probably contributed to recently warmer surface conditions on the west side of the <span class="hlt">Antarctic</span> Peninsula, where air temperatures have increased by approximately 0.5 C/decade since the mid-1940's. The sea ice decline included multiyear cycles of several years in length superimposed on high interannual variability. The retreat was strongest in summer, and would have lowered the regional mean ice thickness, with attendant impacts upon vertical heat flux and the formation of snow ice and brine. The cause of the regional warming and loss of sea ice is believed to be linked to large-scale circulation changes in the atmosphere and <span class="hlt">ocean</span>. At the eastern end of the Weddell Gyre, the Cosmonaut Polyna revealed greater activity since 1986, a recurrence pattern during recent winters and two possible modes of formation. Persistence in polynya location was noted off Cape Ann, where the coastal current can interact more strongly with the <span class="hlt">Antarctic</span> Circumpolar Current. As a result of vorticity conservation, locally enhanced upwelling brings warmer deep water into the mixed layer, causing divergence and melting. In the Ross Sea, ice extent fluctuates over periods of several years, with summer minima and winter maxima roughly in phase. This leads to large interannual cycles of sea ice range, which correlate positively with meridinal winds, regional air temperatures and subsequent shelf water salinities. Deep shelf waters display considerable interannual variability, but have freshened by approximately 0.03/decade</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.C32B..05B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.C32B..05B"><span>Expanding <span class="hlt">Antarctic</span> Sea Ice: Anthropogenic or Natural Variability?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bitz, C. M.</p> <p>2016-12-01</p> <p><span class="hlt">Antarctic</span> sea ice extent has increased over the last 36 years according to the satellite record. Concurrent with <span class="hlt">Antarctic</span> sea-ice expansion has been broad cooling of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> sea-surface temperature. Not only are <span class="hlt">Southern</span> <span class="hlt">Ocean</span> sea ice and SST trends at odds with expectations from greenhouse gas-induced warming, the trend patterns are not reproduced in historical simulations with comprehensive global climate models. While a variety of different factors may have contributed to the observed trends in recent decades, we propose that it is atmospheric circulation changes - and the changes in <span class="hlt">ocean</span> circulation they induce - that have emerged as the most likely cause of the observed <span class="hlt">Southern</span> <span class="hlt">Ocean</span> sea ice and SST trends. I will discuss deficiencies in models that could explain their incorrect response. In addition, I will present results from a series of experiments where the <span class="hlt">Antarctic</span> sea ice and <span class="hlt">ocean</span> are forced by atmospheric perturbations imposed within a coupled climate model. Figure caption: Linear trends of annual-mean SST (left) and annual-mean sea-ice concentration (right) over 1980-2014. SST is from NOAA's Optimum Interpolation SST dataset (version 2; Reynolds et al. 2002). Sea-ice concentration is from passive microwave observations using the NASA Team algorithm. Only the annual means are shown here for brevity and because the signal to noise is greater than in the seasonal means. Figure from Armour and Bitz (2015).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-s48-152-007.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-s48-152-007.html"><span>Breakup of Pack Ice, <span class="hlt">Antarctic</span> Ice Shelf</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>1991-09-18</p> <p>STS048-152-007 (12-18 Sept 1991) --- The periphery of the <span class="hlt">Antarctic</span> ice shelf and the <span class="hlt">Antarctic</span> Peninsula were photographed by the STS 48 crew members. Strong offshore winds, probably associated with katabatic winds from the interior of the continent, are peeling off the edges of the ice shelf into ribbons of sea ice, icebergs, bergy bits and growlers into the cold waters of the circum-<span class="hlt">Antarctic</span> <span class="hlt">southern</span> <span class="hlt">ocean</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.A11C0030M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.A11C0030M"><span>Tropical teleconnections via the <span class="hlt">ocean</span> and atmosphere induced by <span class="hlt">Southern</span> <span class="hlt">Ocean</span> deep convective events</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marinov, I.; Cabre, A.; Gunn, A.; Gnanadesikan, A.</p> <p>2016-12-01</p> <p>The current generation (CMIP5) of Earth System Models (ESMs) shows a huge variability in their ability to represent <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (SO) deep-<span class="hlt">ocean</span> convection and <span class="hlt">Antarctic</span> Bottom Water, with a preference for open-sea convection in the Weddell and Ross gyres. A long control simulation in a coarse 3o resolution ESM (the GFDL CM2Mc model) shows a highly regular multi-decadal oscillation between periods of SO open sea convection and non-convective periods. This process also happens naturally, with different frequencies and durations of convection across most CMIP5 models under preindustrial forcing (deLavergne et al, 2014). Here we assess the impact of SO deep convection and resulting sea surface temperature (SST) anomalies on the tropical atmosphere and <span class="hlt">ocean</span> via teleconnections, with a focus on interannual to multi-decadal timescales. We combine analysis of our low-resolution coupled model with inter-model analysis across historical CMIP5 simulations. SST cooling south of 60S during non-convective decades triggers a stronger, northward shifted SH Hadley cell, which results in intensified northward cross-equatorial moist heat transport and a poleward shift in the ITCZ. Resulting correlations between the cross-equatorial atmospheric heat transport and ITCZ location are in good agreement with recent theories (e.g. Frierson et al. 2013; Donohoe et al. 2014). Lagged correlations between a SO convective index and cross-equatorial heat transports (in the atmosphere and <span class="hlt">ocean</span>), as well as various tropical (and ENSO) climate indices are analyzed. In the <span class="hlt">ocean</span> realm, we find that non-convective decades result in weaker AABW formation and weaker ACC but stronger <span class="hlt">Antarctic</span> Intermediate Water (AAIW) formation, likely as a result of stronger SO westerlies (more positive SAM). The signals of AABW and AAIW are seen in the tropics on short timescales of years to decades in the temperature, heat storage and heat transport anomalies and also in deep and intermediate <span class="hlt">ocean</span> oxygen. Most</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29046532','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29046532"><span>Cradles and museums of <span class="hlt">Antarctic</span> teleost biodiversity.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dornburg, Alex; Federman, Sarah; Lamb, April D; Jones, Christopher D; Near, Thomas J</p> <p>2017-09-01</p> <p>Isolated in one of the most extreme marine environments on Earth, teleost fish diversity in Antarctica's <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is dominated by one lineage: the notothenioids. Throughout the past century, the long-term persistence of this unique marine fauna has become increasingly threatened by regional atmospheric and, to a lesser extent <span class="hlt">oceanic</span>, warming. Developing an understanding of how historical temperature shifts have shaped source-sink dynamics for Antarctica's teleost lineages provides critical insight for predicting future demographic responses to climate change. We use a combination of phylogenetic and biogeographic modelling to show that high-latitude <span class="hlt">Antarctic</span> nearshore habitats have been an evolutionary sink for notothenioid species diversity. Contrary to expectations from island biogeographic theory, lower latitude regions of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> that include the northern <span class="hlt">Antarctic</span> Peninsula and peripheral island archipelagos act as source areas to continental diversity. These peripheral areas facilitate both the generation of new species and repeated colonization of nearshore <span class="hlt">Antarctic</span> continental regions. Our results provide historical context to contemporary trends of global climate change that threaten to invert these evolutionary dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28873966','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28873966"><span>Draft genome of the <span class="hlt">Antarctic</span> dragonfish, Parachaenichthys charcoti.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ahn, Do-Hwan; Shin, Seung Chul; Kim, Bo-Mi; Kang, Seunghyun; Kim, Jin-Hyoung; Ahn, Inhye; Park, Joonho; Park, Hyun</p> <p>2017-08-01</p> <p>The <span class="hlt">Antarctic</span> bathydraconid dragonfish, Parachaenichthys charcoti, is an <span class="hlt">Antarctic</span> notothenioid teleost endemic to the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> has cooled to -1.8ºC over the past 30 million years, and the seawater had retained this cold temperature and isolated <span class="hlt">oceanic</span> environment because of the <span class="hlt">Antarctic</span> Circumpolar Current. Notothenioids dominate <span class="hlt">Antarctic</span> fish, making up 90% of the biomass, and all notothenioids have undergone molecular and ecological diversification to survive in this cold environment. Therefore, they are considered an attractive <span class="hlt">Antarctic</span> fish model for evolutionary and ancestral genomic studies. Bathydraconidae is a speciose family of the Notothenioidei, the dominant taxonomic component of <span class="hlt">Antarctic</span> teleosts. To understand the process of evolution of <span class="hlt">Antarctic</span> fish, we select a typical <span class="hlt">Antarctic</span> bathydraconid dragonfish, P. charcoti. Here, we have sequenced, de novo assembled, and annotated a comprehensive genome from P. charcoti. The draft genome of P. charcoti is 709 Mb in size. The N50 contig length is 6145 bp, and its N50 scaffold length 178 362 kb. The genome of P. charcoti is predicted to contain 32 712 genes, 18 455 of which have been assigned preliminary functions. A total of 8951 orthologous groups common to 7 species of fish were identified, while 333 genes were identified in P. charcoti only; 2519 orthologous groups were also identified in both P. charcoti and N. coriiceps, another <span class="hlt">Antarctic</span> fish. Four gene ontology terms were statistically overrepresented among the 333 genes unique to P. charcoti, according to gene ontology enrichment analysis. The draft P. charcoti genome will broaden our understanding of the evolution of <span class="hlt">Antarctic</span> fish in their extreme environment. It will provide a basis for further investigating the unusual characteristics of <span class="hlt">Antarctic</span> fishes. © The Author 2017. Published by Oxford University Press.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2596239','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2596239"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> acidification: A tipping point at 450-ppm atmospheric CO2</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>McNeil, Ben I.; Matear, Richard J.</p> <p>2008-01-01</p> <p><span class="hlt">Southern</span> <span class="hlt">Ocean</span> acidification via anthropogenic CO2 uptake is expected to be detrimental to multiple calcifying plankton species by lowering the concentration of carbonate ion (CO32−) to levels where calcium carbonate (both aragonite and calcite) shells begin to dissolve. Natural seasonal variations in carbonate ion concentrations could either hasten or dampen the future onset of this undersaturation of calcium carbonate. We present a large-scale <span class="hlt">Southern</span> <span class="hlt">Ocean</span> observational analysis that examines the seasonal magnitude and variability of CO32− and pH. Our analysis shows an intense wintertime minimum in CO32− south of the <span class="hlt">Antarctic</span> Polar Front and when combined with anthropogenic CO2 uptake is likely to induce aragonite undersaturation when atmospheric CO2 levels reach ≈450 ppm. Under the IPCC IS92a scenario, <span class="hlt">Southern</span> <span class="hlt">Ocean</span> wintertime aragonite undersaturation is projected to occur by the year 2030 and no later than 2038. Some prominent calcifying plankton, in particular the Pteropod species Limacina helicina, have important veliger larval development during winter and will have to experience detrimental carbonate conditions much earlier than previously thought, with possible deleterious flow-on impacts for the wider <span class="hlt">Southern</span> <span class="hlt">Ocean</span> marine ecosystem. Our results highlight the critical importance of understanding seasonal carbon dynamics within all calcifying marine ecosystems such as continental shelves and coral reefs, because natural variability may potentially hasten the onset of future <span class="hlt">ocean</span> acidification. PMID:19022908</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19022908','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19022908"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> acidification: a tipping point at 450-ppm atmospheric CO2.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McNeil, Ben I; Matear, Richard J</p> <p>2008-12-02</p> <p><span class="hlt">Southern</span> <span class="hlt">Ocean</span> acidification via anthropogenic CO(2) uptake is expected to be detrimental to multiple calcifying plankton species by lowering the concentration of carbonate ion (CO(3)(2-)) to levels where calcium carbonate (both aragonite and calcite) shells begin to dissolve. Natural seasonal variations in carbonate ion concentrations could either hasten or dampen the future onset of this undersaturation of calcium carbonate. We present a large-scale <span class="hlt">Southern</span> <span class="hlt">Ocean</span> observational analysis that examines the seasonal magnitude and variability of CO(3)(2-) and pH. Our analysis shows an intense wintertime minimum in CO(3)(2-) south of the <span class="hlt">Antarctic</span> Polar Front and when combined with anthropogenic CO(2) uptake is likely to induce aragonite undersaturation when atmospheric CO(2) levels reach approximately 450 ppm. Under the IPCC IS92a scenario, <span class="hlt">Southern</span> <span class="hlt">Ocean</span> wintertime aragonite undersaturation is projected to occur by the year 2030 and no later than 2038. Some prominent calcifying plankton, in particular the Pteropod species Limacina helicina, have important veliger larval development during winter and will have to experience detrimental carbonate conditions much earlier than previously thought, with possible deleterious flow-on impacts for the wider <span class="hlt">Southern</span> <span class="hlt">Ocean</span> marine ecosystem. Our results highlight the critical importance of understanding seasonal carbon dynamics within all calcifying marine ecosystems such as continental shelves and coral reefs, because natural variability may potentially hasten the onset of future <span class="hlt">ocean</span> acidification.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5784396','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5784396"><span>The Signature of <span class="hlt">Southern</span> Hemisphere Atmospheric Circulation Patterns in <span class="hlt">Antarctic</span> Precipitation</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Thompson, David W. J.; van den Broeke, Michiel R.</p> <p>2017-01-01</p> <p>Abstract We provide the first comprehensive analysis of the relationships between large‐scale patterns of <span class="hlt">Southern</span> Hemisphere climate variability and the detailed structure of <span class="hlt">Antarctic</span> precipitation. We examine linkages between the high spatial resolution precipitation from a regional atmospheric model and four patterns of large‐scale <span class="hlt">Southern</span> Hemisphere climate variability: the <span class="hlt">southern</span> baroclinic annular mode, the <span class="hlt">southern</span> annular mode, and the two Pacific‐South American teleconnection patterns. Variations in all four patterns influence the spatial configuration of precipitation over Antarctica, consistent with their signatures in high‐latitude meridional moisture fluxes. They impact not only the mean but also the incidence of extreme precipitation events. Current coupled‐climate models are able to reproduce all four patterns of atmospheric variability but struggle to correctly replicate their regional impacts on <span class="hlt">Antarctic</span> climate. Thus, linking these patterns directly to <span class="hlt">Antarctic</span> precipitation variability may allow a better estimate of future changes in precipitation than using model output alone. PMID:29398735</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28663586','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28663586"><span>Radiocarbon as a Novel Tracer of Extra-<span class="hlt">Antarctic</span> Feeding in <span class="hlt">Southern</span> Hemisphere Humpback Whales.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Eisenmann, Pascale; Fry, Brian; Mazumder, Debashish; Jacobsen, Geraldine; Holyoake, Carlysle Sian; Coughran, Douglas; Bengtson Nash, Susan</p> <p>2017-06-29</p> <p>Bulk stable isotope analysis provides information regarding food web interactions, and has been applied to several cetacean species for the study of migration ecology. One limitation in bulk stable isotope analysis arises when a species, such as <span class="hlt">Southern</span> hemisphere humpback whales, utilises geographically distinct food webs with differing isotopic baselines. Migrations to areas with different baselines can result in isotopic changes that mimic changes in feeding relations, leading to ambiguous food web interpretations. Here, we demonstrate the novel application of radiocarbon measurement for the resolution of such ambiguities. Radiocarbon was measured in baleen plates from humpback whales stranded in Australia between 2007 and 2013, and in skin samples collected in Australia and Antarctica from stranded and free-ranging animals. Radiocarbon measurements showed lower values for <span class="hlt">Southern</span> <span class="hlt">Ocean</span> feeding than for extra-<span class="hlt">Antarctic</span> feeding in Australian waters. While the whales mostly relied on <span class="hlt">Antarctic</span>-derived energy stores during their annual migration, there was some evidence of feeding within temperate zone waters in some individuals. This work, to our knowledge, provides the first definitive biochemical evidence for supplementary feeding by <span class="hlt">southern</span> hemisphere humpback whales within temperate waters during migration. Further, the work contributes a powerful new tool (radiocarbon) for tracing source regions and geographical feeding.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26438285','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26438285"><span>Atmospheric and <span class="hlt">oceanic</span> impacts of <span class="hlt">Antarctic</span> glaciation across the Eocene-Oligocene transition.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kennedy, A T; Farnsworth, A; Lunt, D J; Lear, C H; Markwick, P J</p> <p>2015-11-13</p> <p>The glaciation of Antarctica at the Eocene-Oligocene transition (approx. 34 million years ago) was a major shift in the Earth's climate system, but the mechanisms that caused the glaciation, and its effects, remain highly debated. A number of recent studies have used coupled atmosphere-<span class="hlt">ocean</span> climate models to assess the climatic effects of <span class="hlt">Antarctic</span> glacial inception, with often contrasting results. Here, using the HadCM3L model, we show that the global atmosphere and <span class="hlt">ocean</span> response to growth of the <span class="hlt">Antarctic</span> ice sheet is sensitive to subtle variations in palaeogeography, using two reconstructions representing Eocene and Oligocene geological stages. The earlier stage (Eocene; Priabonian), which has a relatively constricted Tasman Seaway, shows a major increase in sea surface temperature over the Pacific sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in response to the ice sheet. This response does not occur for the later stage (Oligocene; Rupelian), which has a more open Tasman Seaway. This difference in temperature response is attributed to reorganization of <span class="hlt">ocean</span> currents between the stages. Following ice sheet expansion in the earlier stage, the large Ross Sea gyre circulation decreases in size. Stronger zonal flow through the Tasman Seaway allows salinities to increase in the Ross Sea, deep-water formation initiates and multiple feedbacks then occur amplifying the temperature response. This is potentially a model-dependent result, but it highlights the sensitive nature of model simulations to subtle variations in palaeogeography, and highlights the need for coupled ice sheet-climate simulations to properly represent and investigate feedback processes acting on these time scales. © 2015 The Author(s).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27187527','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27187527"><span>Biological and physical controls in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> on past millennial-scale atmospheric CO2 changes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gottschalk, Julia; Skinner, Luke C; Lippold, Jörg; Vogel, Hendrik; Frank, Norbert; Jaccard, Samuel L; Waelbroeck, Claire</p> <p>2016-05-17</p> <p>Millennial-scale climate changes during the last glacial period and deglaciation were accompanied by rapid changes in atmospheric CO2 that remain unexplained. While the role of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> as a 'control valve' on <span class="hlt">ocean</span>-atmosphere CO2 exchange has been emphasized, the exact nature of this role, in particular the relative contributions of physical (for example, <span class="hlt">ocean</span> dynamics and air-sea gas exchange) versus biological processes (for example, export productivity), remains poorly constrained. Here we combine reconstructions of bottom-water [O2], export production and (14)C ventilation ages in the sub-<span class="hlt">Antarctic</span> Atlantic, and show that atmospheric CO2 pulses during the last glacial- and deglacial periods were consistently accompanied by decreases in the biological export of carbon and increases in deep-<span class="hlt">ocean</span> ventilation via <span class="hlt">southern</span>-sourced water masses. These findings demonstrate how the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>'s 'organic carbon pump' has exerted a tight control on atmospheric CO2, and thus global climate, specifically via a synergy of both physical and biological processes.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1712219S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1712219S"><span><span class="hlt">Oceanic</span> an climatic consequences of a sudden large-scale West <span class="hlt">Antarctic</span> Ice Sheet collapse</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scarff, Katie; Green, Mattias; Schmittner, Andreas</p> <p>2015-04-01</p> <p>Atmospheric warming is progressing to the point where the West <span class="hlt">Antarctic</span> Ice Sheet (WAIS) will experience an elevated rate of discharge. The current discharge rate of WAIS is around 0.005Sv, but this rate will most likely accelerate over this century. The input of freshwater, in the form of ice, may have a profound effect on <span class="hlt">oceanic</span> circulation systems, including potentially reducing the formation of deep water in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and thus triggering or enhancing the bipolar seesaw. Using UVic - an intermediate complexity <span class="hlt">ocean</span>-climate model - we investigate how various hosing rates from the WAIS will impact of the present and future <span class="hlt">ocean</span> circulation and climate. These scenarios range from observed hosing rates (~0.005Sv) being applied for 100 years, to a total collapse of the WAIS over the next 100 years (the equivalent to a0.7Sv hosing). We show that even the present day observed rates can have a significant impact on the <span class="hlt">ocean</span> and atmospheric temperatures, and that the bipolar seesaw may indeed be enhanced by the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> hosing. Consequently, there is a speed-up of the Meridional Overturning Circulation (MOC) early on during the hosing, which leads to a warming over the North Atlantic, and a subsequent reduction in the MOC on centennial scales. The larger hosing cases show more dramatic effects with near-complete shutdowns of the MOC during the hosing. Furthermore, global warming scenarios based on the IPCC "business as usual" scenario show that the atmospheric warming will change the response of the <span class="hlt">ocean</span> to <span class="hlt">Southern</span> <span class="hlt">Ocean</span> hosing and that the warming will dominate the perturbation. The potential feedback between changes in the <span class="hlt">ocean</span> stratification in the scenarios and tidally driven abyssal mixing via tidal conversion is also explored.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5102468','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5102468"><span>Seasonal and Diel Vocalization Patterns of <span class="hlt">Antarctic</span> Blue Whale (Balaenoptera musculus intermedia) in the <span class="hlt">Southern</span> Indian <span class="hlt">Ocean</span>: A Multi-Year and Multi-Site Study</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Leroy, Emmanuelle C.; Samaran, Flore; Bonnel, Julien; Royer, Jean-Yves</p> <p>2016-01-01</p> <p>Passive acoustic monitoring is an efficient way to provide insights on the ecology of large whales. This approach allows for long-term and species-specific monitoring over large areas. In this study, we examined six years (2010 to 2015) of continuous acoustic recordings at up to seven different locations in the Central and <span class="hlt">Southern</span> Indian Basin to assess the peak periods of presence, seasonality and migration movements of <span class="hlt">Antarctic</span> blue whales (Balaenoptera musculus intermedia). An automated method is used to detect the <span class="hlt">Antarctic</span> blue whale stereotyped call, known as Z-call. Detection results are analyzed in terms of distribution, seasonal presence and diel pattern of emission at each site. Z-calls are detected year-round at each site, except for one located in the equatorial Indian <span class="hlt">Ocean</span>, and display highly seasonal distribution. This seasonality is stable across years for every site, but varies between sites. Z-calls are mainly detected during autumn and spring at the subantarctic locations, suggesting that these sites are on the <span class="hlt">Antarctic</span> blue whale migration routes, and mostly during winter at the subtropical sites. In addition to these seasonal trends, there is a significant diel pattern in Z-call emission, with more Z-calls in daytime than in nighttime. This diel pattern may be related to the blue whale feeding ecology. PMID:27828976</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26840491','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26840491"><span>Covariation of deep <span class="hlt">Southern</span> <span class="hlt">Ocean</span> oxygenation and atmospheric CO2 through the last ice age.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jaccard, Samuel L; Galbraith, Eric D; Martínez-García, Alfredo; Anderson, Robert F</p> <p>2016-02-11</p> <p>No single mechanism can account for the full amplitude of past atmospheric carbon dioxide (CO2) concentration variability over glacial-interglacial cycles. A build-up of carbon in the deep <span class="hlt">ocean</span> has been shown to have occurred during the Last Glacial Maximum. However, the mechanisms responsible for the release of the deeply sequestered carbon to the atmosphere at deglaciation, and the relative importance of deep <span class="hlt">ocean</span> sequestration in regulating millennial-timescale variations in atmospheric CO2 concentration before the Last Glacial Maximum, have remained unclear. Here we present sedimentary redox-sensitive trace-metal records from the <span class="hlt">Antarctic</span> Zone of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> that provide a reconstruction of transient changes in deep <span class="hlt">ocean</span> oxygenation and, by inference, respired carbon storage throughout the last glacial cycle. Our data suggest that respired carbon was removed from the abyssal <span class="hlt">Southern</span> <span class="hlt">Ocean</span> during the Northern Hemisphere cold phases of the deglaciation, when atmospheric CO2 concentration increased rapidly, reflecting--at least in part--a combination of dwindling iron fertilization by dust and enhanced deep <span class="hlt">ocean</span> ventilation. Furthermore, our records show that the observed covariation between atmospheric CO2 concentration and abyssal <span class="hlt">Southern</span> <span class="hlt">Ocean</span> oxygenation was maintained throughout most of the past 80,000 years. This suggests that on millennial timescales deep <span class="hlt">ocean</span> circulation and iron fertilization in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> played a consistent role in modifying atmospheric CO2 concentration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4768674','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4768674"><span>The past, present and future distribution of a deep-sea shrimp in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Costello, Mark J.</p> <p>2016-01-01</p> <p>Shrimps have a widespread distribution across the shelf, slope and seamount regions of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Studies of <span class="hlt">Antarctic</span> organisms have shown that individual species and higher taxa display different degrees of sensitivity and adaptability in response to environmental change. We use species distribution models to predict changes in the geographic range of the deep-sea <span class="hlt">Antarctic</span> shrimp Nematocarcinus lanceopes under changing climatic conditions from the Last Glacial Maximum to the present and to the year 2100. The present distribution range indicates a pole-ward shift of the shrimp population since the last glaciation. This occurred by colonization of slopes from nearby refugia located around the northern part of Scotia Arc, <span class="hlt">southern</span> tip of South America, South Georgia, Bouvet Island, <span class="hlt">southern</span> tip of the Campbell plateau and Kerguelen plateau. By 2100, the shrimp are likely to expand their distribution in east Antarctica but have a continued pole-ward contraction in west Antarctica. The range extension and contraction process followed by the deep-sea shrimp provide a geographic context of how other deep-sea <span class="hlt">Antarctic</span> species may have survived during the last glaciation and may endure with projected changing climatic conditions in the future. PMID:26925334</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26925334','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26925334"><span>The past, present and future distribution of a deep-sea shrimp in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Basher, Zeenatul; Costello, Mark J</p> <p>2016-01-01</p> <p>Shrimps have a widespread distribution across the shelf, slope and seamount regions of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Studies of <span class="hlt">Antarctic</span> organisms have shown that individual species and higher taxa display different degrees of sensitivity and adaptability in response to environmental change. We use species distribution models to predict changes in the geographic range of the deep-sea <span class="hlt">Antarctic</span> shrimp Nematocarcinus lanceopes under changing climatic conditions from the Last Glacial Maximum to the present and to the year 2100. The present distribution range indicates a pole-ward shift of the shrimp population since the last glaciation. This occurred by colonization of slopes from nearby refugia located around the northern part of Scotia Arc, <span class="hlt">southern</span> tip of South America, South Georgia, Bouvet Island, <span class="hlt">southern</span> tip of the Campbell plateau and Kerguelen plateau. By 2100, the shrimp are likely to expand their distribution in east Antarctica but have a continued pole-ward contraction in west Antarctica. The range extension and contraction process followed by the deep-sea shrimp provide a geographic context of how other deep-sea <span class="hlt">Antarctic</span> species may have survived during the last glaciation and may endure with projected changing climatic conditions in the future.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15525989','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15525989"><span>Long-term decline in krill stock and increase in salps within the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Atkinson, Angus; Siegel, Volker; Pakhomov, Evgeny; Rothery, Peter</p> <p>2004-11-04</p> <p><span class="hlt">Antarctic</span> krill (Euphausia superba) and salps (mainly Salpa thompsoni) are major grazers in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, and krill support commercial fisheries. Their density distributions have been described in the period 1926-51, while recent localized studies suggest short-term changes. To examine spatial and temporal changes over larger scales, we have combined all available scientific net sampling data from 1926 to 2003. This database shows that the productive southwest Atlantic sector contains >50% of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> krill stocks, but here their density has declined since the 1970s. Spatially, within their habitat, summer krill density correlates positively with chlorophyll concentrations. Temporally, within the southwest Atlantic, summer krill densities correlate positively with sea-ice extent the previous winter. Summer food and the extent of winter sea ice are thus key factors in the high krill densities observed in the southwest Atlantic <span class="hlt">Ocean</span>. Krill need the summer phytoplankton blooms of this sector, where winters of extensive sea ice mean plentiful winter food from ice algae, promoting larval recruitment and replenishing the stock. Salps, by contrast, occupy the extensive lower-productivity regions of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and tolerate warmer water than krill. As krill densities decreased last century, salps appear to have increased in the <span class="hlt">southern</span> part of their range. These changes have had profound effects within the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> food web.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMPP14B..05M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMPP14B..05M"><span>Sensitivity of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> overturning circulation to surface buoyancy forcing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Morrison, A.; Hogg, A.; Ward, M.</p> <p>2011-12-01</p> <p>The <span class="hlt">southern</span> limb of the <span class="hlt">ocean</span>'s meridional overturning circulation plays a key role in the Earth's response to climate change. The rise in atmospheric CO2 during glacial-interglacial transitions has been attributed to outgassing of enhanced upwelling water masses in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. However a dynamical understanding of the physical mechanisms driving the change in overturning is lacking. Previous modelling studies of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> have focused on the effect of wind stress forcing on the overturning, while largely neglecting the response of the upper overturning cell to changes in surface buoyancy forcing. Using a series of eddy-permitting, idealised simulations of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, we show that surface buoyancy forcing in the mid-latitudes is likely to play a significant role in setting the strength of the overturning circulation. Air-sea fluxes of heat and precipitation over the <span class="hlt">Antarctic</span> Circumpolar Current region act to convert dense upwelled water masses into lighter waters at the surface. Additional fluxes of heat or freshwater thereby facilitate the meridional overturning up to a theoretical limit derived from Ekman transport. The sensitivity of the overturning to surface buoyancy forcing is strongly dependent on the relative locations of the wind stress profile, buoyancy forcing and upwelling region. The idealised model results provide support for the hypothesis that changes in upwelling during deglaciations may have been driven by changes in heat and freshwater fluxes, instead of, or in addition to, changes in wind stress. Morrison, A. K., A. M. Hogg, and M. L. Ward (2011), Sensitivity of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> overturning circulation to surface buoyancy forcing, <it>Geophys. Res. Lett.</it>, 38, L14602, doi:10.1029/2011GL048031.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25517505','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25517505"><span>Effects of whaling on the structure of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> food web: insights on the "krill surplus" from ecosystem modelling.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Surma, Szymon; Pakhomov, Evgeny A; Pitcher, Tony J</p> <p>2014-01-01</p> <p>The aim of this study was to examine the ecological plausibility of the "krill surplus" hypothesis and the effects of whaling on the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> food web using mass-balance ecosystem modelling. The depletion trajectory and unexploited biomass of each rorqual population in the <span class="hlt">Antarctic</span> was reconstructed using yearly catch records and a set of species-specific surplus production models. The resulting estimates of the unexploited biomass of <span class="hlt">Antarctic</span> rorquals were used to construct an Ecopath model of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> food web existing in 1900. The rorqual depletion trajectory was then used in an Ecosim scenario to drive rorqual biomasses and examine the "krill surplus" phenomenon and whaling effects on the food web in the years 1900-2008. An additional suite of Ecosim scenarios reflecting several hypothetical trends in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> primary productivity were employed to examine the effect of bottom-up forcing on the documented krill biomass trend. The output of the Ecosim scenarios indicated that while the "krill surplus" hypothesis is a plausible explanation of the biomass trends observed in some penguin and pinniped species in the mid-20th century, the excess krill biomass was most likely eliminated by a rapid decline in primary productivity in the years 1975-1995. Our findings suggest that changes in physical conditions in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> during this time period could have eliminated the ecological effects of rorqual depletion, although the mechanism responsible is currently unknown. Furthermore, a decline in iron bioavailability due to rorqual depletion may have contributed to the rapid decline in overall <span class="hlt">Southern</span> <span class="hlt">Ocean</span> productivity during the last quarter of the 20th century. The results of this study underscore the need for further research on historical changes in the roles of top-down and bottom-up forcing in structuring the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> food web.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4873644','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4873644"><span>Biological and physical controls in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> on past millennial-scale atmospheric CO2 changes</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Gottschalk, Julia; Skinner, Luke C.; Lippold, Jörg; Vogel, Hendrik; Frank, Norbert; Jaccard, Samuel L.; Waelbroeck, Claire</p> <p>2016-01-01</p> <p>Millennial-scale climate changes during the last glacial period and deglaciation were accompanied by rapid changes in atmospheric CO2 that remain unexplained. While the role of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> as a 'control valve' on ocean–atmosphere CO2 exchange has been emphasized, the exact nature of this role, in particular the relative contributions of physical (for example, <span class="hlt">ocean</span> dynamics and air–sea gas exchange) versus biological processes (for example, export productivity), remains poorly constrained. Here we combine reconstructions of bottom-water [O2], export production and 14C ventilation ages in the sub-<span class="hlt">Antarctic</span> Atlantic, and show that atmospheric CO2 pulses during the last glacial- and deglacial periods were consistently accompanied by decreases in the biological export of carbon and increases in deep-<span class="hlt">ocean</span> ventilation via <span class="hlt">southern</span>-sourced water masses. These findings demonstrate how the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>'s 'organic carbon pump' has exerted a tight control on atmospheric CO2, and thus global climate, specifically via a synergy of both physical and biological processes. PMID:27187527</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011DSRII..58.2293H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011DSRII..58.2293H"><span>Distribution, abundance and seasonal flux of pteropods in the Sub-<span class="hlt">Antarctic</span> Zone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Howard, W. R.; Roberts, D.; Moy, A. D.; Lindsay, M. C. M.; Hopcroft, R. R.; Trull, T. W.; Bray, S. G.</p> <p>2011-11-01</p> <p>Pteropods were identified from epipelagic net and trawl samples in the Sub-<span class="hlt">Antarctic</span> Zone during the 2007 mid-summer (January 17-February 20) Sub-<span class="hlt">Antarctic</span> Zone Sensitivity to Environmental Change (SAZ-Sense) voyage, as well as in a moored sediment trap in the same region. Overall pteropod densities during SAZ-Sense were lower than those reported for higher-latitude <span class="hlt">Southern</span> <span class="hlt">Ocean</span> waters. The four major contributors to the Sub-<span class="hlt">Antarctic</span> Zone pteropod community during the SAZ-Sense voyage, Clio pyramidata forma antarctica, Clio recurva, Limacina helicina antarctica and Limacina retroversa australis, accounted for 93% of all pteropods observed. The distribution of the two dominant pteropods collected in the Sub-<span class="hlt">Antarctic</span> Zone, L. retroversa australis and C. pyramidata forma antarctica, is strongly related to latitude and depth. L. retroversa australis is typical of cold <span class="hlt">southern</span> (50-54°S) polar waters and C. pyramidata forma antarctica is typical of shallow (top 20 m) Sub-<span class="hlt">Antarctic</span> Zone waters. A moored sediment trap deployed to 2100 m at 47°S, 141°E in 2003/04 showed the pteropod flux in the Sub-<span class="hlt">Antarctic</span> Zone had late-Spring and mid-summer peaks. The diversity, abundance and distribution of pteropods collected during SAZ-Sense provide a timely benchmark against which to monitor future changes in SAZ <span class="hlt">ocean</span> pteropod communities, particularly in light of predictions of declining aragonite saturation in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> by the end of the century.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMPP23D2080M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMPP23D2080M"><span>Paleoceanographic Changes during the Past 95000 Years from the Indian Sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Manoj, M. C.; Meloth, T.; Mohan, R.</p> <p>2012-12-01</p> <p>High-resolution planktic/benthic foraminiferal stable isotope and mean sortable silt records in a sediment core (SK200/22a) from the sub-<span class="hlt">Antarctic</span> regime of the Indian sector of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> depict the variations in surface and deep water hydrography during the past 95,000 years. The δ18O records of shallow- and deep-dwelling planktonic foraminiferal species (Neogloboquadrina pachyderma, Globigerina bulloides and Globorotalia inflata), primarily reflects the changes in upper water column characteristics. The δ18O records revealed the presence of the <span class="hlt">Antarctic</span> Cold Reversal and the timing of the variability in major surface warming events appears in phase with the <span class="hlt">Antarctic</span> temperature variations at the millennial time scale. Comparison between the proxies of sea surface conditions like planktonic δ18O and productivity proxies like carbonate and biogenic opal content in the core indicate that millennial scale sea surface warming fluctuated with productivity. The marine isotopic stage (MIS) 1 and MIS2 are characterized by near constant variations in mean sortable silt values, negating any significant changes in the deep water flow during these periods. The MIS 3 - MIS 5 periods were characterized by a general increase in mean sortable silt value, suggesting a strengthening of bottom-current activity that triggered winnowing at these periods. This is supported by the low δ13C records of epibenthic Cibicidoides wuellerstorfi during the glacials and some parts of MIS3 and MIS 5, confirming older nutrient-rich and poorly ventilated <span class="hlt">southern</span> sourced deep waters at these periods. The termination I is marked by decrease in flow speed and an increase in the C. wuellerstorfi δ13C values. Comparison of mean sortable silt and C. wuellerstorfi δ13C record with the <span class="hlt">Antarctic</span> ice core records reveal that pulses of reduced bottom water flow of Circumpolar Deep Water/North Atlantic Deep Water are synchronous with the <span class="hlt">Antarctic</span> warming events. The decreased flow speed during</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017OcDyn..67..813D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017OcDyn..67..813D"><span>Modification of the deep salinity-maximum in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> by circulation in the <span class="hlt">Antarctic</span> Circumpolar Current and the Weddell Gyre</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Donnelly, Matthew; Leach, Harry; Strass, Volker</p> <p>2017-07-01</p> <p>The evolution of the deep salinity-maximum associated with the Lower Circumpolar Deep Water (LCDW) is assessed using a set of 37 hydrographic sections collected over a 20-year period in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> as part of the WOCE/CLIVAR programme. A circumpolar decrease in the value of the salinity-maximum is observed eastwards from the North Atlantic Deep Water (NADW) in the Atlantic sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> through the Indian and Pacific sectors to Drake Passage. Isopycnal mixing processes are limited by circumpolar fronts, and in the Atlantic sector, this acts to limit the direct poleward propagation of the salinity signal. Limited entrainment occurs into the Weddell Gyre, with LCDW entering primarily through the eddy-dominated eastern limb. A vertical mixing coefficient, κV of (2.86 ± 1.06) × 10-4 m2 s-1 and an isopycnal mixing coefficient, κI of (8.97 ± 1.67) × 102 m2 s-1 are calculated for the eastern Indian and Pacific sectors of the <span class="hlt">Antarctic</span> Circumpolar Current (ACC). A κV of (2.39 ± 2.83) × 10-5 m2 s-1, an order of magnitude smaller, and a κI of (2.47 ± 0.63) × 102 m2 s-1, three times smaller, are calculated for the <span class="hlt">southern</span> and eastern Weddell Gyre reflecting a more turbulent regime in the ACC and a less turbulent regime in the Weddell Gyre. In agreement with other studies, we conclude that the ACC acts as a barrier to direct meridional transport and mixing in the Atlantic sector evidenced by the eastward propagation of the deep salinity-maximum signal, insulating the Weddell Gyre from short-term changes in NADW characteristics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23967221','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23967221"><span>Seasonal and geographic variation of <span class="hlt">southern</span> blue whale subspecies in the Indian <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Samaran, Flore; Stafford, Kathleen M; Branch, Trevor A; Gedamke, Jason; Royer, Jean-Yves; Dziak, Robert P; Guinet, Christophe</p> <p>2013-01-01</p> <p>Understanding the seasonal movements and distribution patterns of migratory species over <span class="hlt">ocean</span> basin scales is vital for appropriate conservation and management measures. However, assessing populations over remote regions is challenging, particularly if they are rare. Blue whales (Balaenoptera musculus spp) are an endangered species found in the <span class="hlt">Southern</span> and Indian <span class="hlt">Oceans</span>. Here two recognized subspecies of blue whales and, based on passive acoustic monitoring, four "acoustic populations" occur. Three of these are pygmy blue whale (B.m. brevicauda) populations while the fourth is the <span class="hlt">Antarctic</span> blue whale (B.m. intermedia). Past whaling catches have dramatically reduced their numbers but recent acoustic recordings show that these <span class="hlt">oceans</span> are still important habitat for blue whales. Presently little is known about the seasonal movements and degree of overlap of these four populations, particularly in the central Indian <span class="hlt">Ocean</span>. We examined the geographic and seasonal occurrence of different blue whale acoustic populations using one year of passive acoustic recording from three sites located at different latitudes in the Indian <span class="hlt">Ocean</span>. The vocalizations of the different blue whale subspecies and acoustic populations were recorded seasonally in different regions. For some call types and locations, there was spatial and temporal overlap, particularly between <span class="hlt">Antarctic</span> and different pygmy blue whale acoustic populations. Except on the southernmost hydrophone, all three pygmy blue whale acoustic populations were found at different sites or during different seasons, which further suggests that these populations are generally geographically distinct. This unusual blue whale diversity in sub-<span class="hlt">Antarctic</span> and sub-tropical waters indicates the importance of the area for blue whales in these former whaling grounds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3814847','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3814847"><span>Levoglucosan indicates high levels of biomass burning aerosols over <span class="hlt">oceans</span> from the Arctic to <span class="hlt">Antarctic</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hu, Qi-Hou; Xie, Zhou-Qing; Wang, Xin-Ming; Kang, Hui; Zhang, Pengfei</p> <p>2013-01-01</p> <p>Biomass burning is known to affect air quality, global carbon cycle, and climate. However, the extent to which biomass burning gases/aerosols are present on a global scale, especially in the marine atmosphere, is poorly understood. Here we report the molecular tracer levoglucosan concentrations in marine air from the Arctic <span class="hlt">Ocean</span> through the North and South Pacific <span class="hlt">Ocean</span> to Antarctica during burning season. Levoglucosan was found to be present in all regions at ng/m3 levels with the highest atmospheric loadings present in the mid-latitudes (30°–60° N and S), intermediate loadings in the Arctic, and lowest loadings in the <span class="hlt">Antarctic</span> and equatorial latitudes. As a whole, levoglucosan concentrations in the <span class="hlt">Southern</span> Hemisphere were comparable to those in the Northern Hemisphere. Biomass burning has a significant impact on atmospheric Hg and water-soluble organic carbon (WSOC) from pole-to-pole, with more contribution to WSOC in the Northern Hemisphere than in the <span class="hlt">Southern</span> Hemisphere. PMID:24176935</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24176935','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24176935"><span>Levoglucosan indicates high levels of biomass burning aerosols over <span class="hlt">oceans</span> from the Arctic to <span class="hlt">Antarctic</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hu, Qi-Hou; Xie, Zhou-Qing; Wang, Xin-Ming; Kang, Hui; Zhang, Pengfei</p> <p>2013-11-01</p> <p>Biomass burning is known to affect air quality, global carbon cycle, and climate. However, the extent to which biomass burning gases/aerosols are present on a global scale, especially in the marine atmosphere, is poorly understood. Here we report the molecular tracer levoglucosan concentrations in marine air from the Arctic <span class="hlt">Ocean</span> through the North and South Pacific <span class="hlt">Ocean</span> to Antarctica during burning season. Levoglucosan was found to be present in all regions at ng/m(3) levels with the highest atmospheric loadings present in the mid-latitudes (30°-60° N and S), intermediate loadings in the Arctic, and lowest loadings in the <span class="hlt">Antarctic</span> and equatorial latitudes. As a whole, levoglucosan concentrations in the <span class="hlt">Southern</span> Hemisphere were comparable to those in the Northern Hemisphere. Biomass burning has a significant impact on atmospheric Hg and water-soluble organic carbon (WSOC) from pole-to-pole, with more contribution to WSOC in the Northern Hemisphere than in the <span class="hlt">Southern</span> Hemisphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23880782','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23880782"><span>Secondary organic aerosols over <span class="hlt">oceans</span> via oxidation of isoprene and monoterpenes from Arctic to <span class="hlt">Antarctic</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hu, Qi-Hou; Xie, Zhou-Qing; Wang, Xin-Ming; Kang, Hui; He, Quan-Fu; Zhang, Pengfei</p> <p>2013-01-01</p> <p>Isoprene and monoterpenes are important precursors of secondary organic aerosols (SOA) in continents. However, their contributions to aerosols over <span class="hlt">oceans</span> are still inconclusive. Here we analyzed SOA tracers from isoprene and monoterpenes in aerosol samples collected over <span class="hlt">oceans</span> during the Chinese Arctic and <span class="hlt">Antarctic</span> Research Expeditions. Combined with literature reports elsewhere, we found that the dominant tracers are the oxidation products of isoprene. The concentrations of tracers varied considerably. The mean average values were approximately one order of magnitude higher in the Northern Hemisphere than in the <span class="hlt">Southern</span> Hemisphere. High values were generally observed in coastal regions. This phenomenon was ascribed to the outflow influence from continental sources. High levels of isoprene could emit from <span class="hlt">oceans</span> and consequently have a significant impact on marine SOA as inferred from isoprene SOA during phytoplankton blooms, which may abruptly increase up to 95 ng/m³ in the boundary layer over remote <span class="hlt">oceans</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4269391','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4269391"><span>Effects of Whaling on the Structure of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Food Web: Insights on the “Krill Surplus” from Ecosystem Modelling</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Surma, Szymon; Pakhomov, Evgeny A.; Pitcher, Tony J.</p> <p>2014-01-01</p> <p>The aim of this study was to examine the ecological plausibility of the “krill surplus” hypothesis and the effects of whaling on the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> food web using mass-balance ecosystem modelling. The depletion trajectory and unexploited biomass of each rorqual population in the <span class="hlt">Antarctic</span> was reconstructed using yearly catch records and a set of species-specific surplus production models. The resulting estimates of the unexploited biomass of <span class="hlt">Antarctic</span> rorquals were used to construct an Ecopath model of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> food web existing in 1900. The rorqual depletion trajectory was then used in an Ecosim scenario to drive rorqual biomasses and examine the “krill surplus” phenomenon and whaling effects on the food web in the years 1900–2008. An additional suite of Ecosim scenarios reflecting several hypothetical trends in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> primary productivity were employed to examine the effect of bottom-up forcing on the documented krill biomass trend. The output of the Ecosim scenarios indicated that while the “krill surplus” hypothesis is a plausible explanation of the biomass trends observed in some penguin and pinniped species in the mid-20th century, the excess krill biomass was most likely eliminated by a rapid decline in primary productivity in the years 1975–1995. Our findings suggest that changes in physical conditions in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> during this time period could have eliminated the ecological effects of rorqual depletion, although the mechanism responsible is currently unknown. Furthermore, a decline in iron bioavailability due to rorqual depletion may have contributed to the rapid decline in overall <span class="hlt">Southern</span> <span class="hlt">Ocean</span> productivity during the last quarter of the 20th century. The results of this study underscore the need for further research on historical changes in the roles of top-down and bottom-up forcing in structuring the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> food web. PMID:25517505</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3757972','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3757972"><span>Bone-eating worms from the <span class="hlt">Antarctic</span>: the contrasting fate of whale and wood remains on the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> seafloor</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Glover, Adrian G.; Wiklund, Helena; Taboada, Sergio; Avila, Conxita; Cristobo, Javier; Smith, Craig R.; Kemp, Kirsty M.; Jamieson, Alan J.; Dahlgren, Thomas G.</p> <p>2013-01-01</p> <p>We report the results from the first experimental study of the fate of whale and wood remains on the <span class="hlt">Antarctic</span> seafloor. Using a baited free-vehicle lander design, we show that whale-falls in the <span class="hlt">Antarctic</span> are heavily infested by at least two new species of bone-eating worm, Osedax antarcticus sp. nov. and Osedax deceptionensis sp. nov. In stark contrast, wood remains are remarkably well preserved with the absence of typical wood-eating fauna such as the xylophagainid bivalves. The combined whale-fall and wood-fall experiment provides support to the hypothesis that the <span class="hlt">Antarctic</span> circumpolar current is a barrier to the larvae of deep-water species that are broadly distributed in other <span class="hlt">ocean</span> basins. Since humans first started exploring the <span class="hlt">Antarctic</span>, wood has been deposited on the seafloor in the form of shipwrecks and waste; our data suggest that this anthropogenic wood may be exceptionally well preserved. Alongside the new species descriptions, we conducted a comprehensive phylogenetic analyses of Osedax, suggesting the clade is most closely related to the frenulate tubeworms, not the vestimentiferans as previous reported. PMID:23945684</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004DSRI...51.1337S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004DSRI...51.1337S"><span><span class="hlt">Antarctic</span>-type blue whale calls recorded at low latitudes in the Indian and eastern Pacific <span class="hlt">Oceans</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stafford, Kathleen M.; Bohnenstiehl, DelWayne R.; Tolstoy, Maya; Chapp, Emily; Mellinger, David K.; Moore, Sue E.</p> <p>2004-10-01</p> <p>Blue whales, Balaenoptera musculus, were once abundant around the <span class="hlt">Antarctic</span> during the austral summer, but intensive whaling during the first half of the 20th century reduced their numbers by over 99%. Although interannual variability of blue whale occurrence on the <span class="hlt">Antarctic</span> feeding grounds was documented by whalers, little was known about where the whales spent the winter months. <span class="hlt">Antarctic</span> blue whales produce calls that are distinct from those produced by blue whales elsewhere in the world. To investigate potential winter migratory destinations of <span class="hlt">Antarctic</span> blue whales, we examined acoustic data for these signals from two low-latitude locales: the eastern tropical Pacific <span class="hlt">Ocean</span> and the Indian <span class="hlt">Ocean</span>. <span class="hlt">Antarctic</span>-type blue whale calls were detected on hydrophones in both regions during the austral autumn and winter (May-September), with peak detections in July. Calls occurred over relatively brief periods in both <span class="hlt">oceans</span>, suggesting that there may be only a few animals migrating so far north and/or producing calls. <span class="hlt">Antarctic</span> blue whales appear to use both the Indian and eastern Pacific <span class="hlt">Oceans</span> concurrently, indicating that there is not a single migratory destination. Acoustic data from the South Atlantic and from mid-latitudes in the Indian or Pacific <span class="hlt">Oceans</span> are needed for a more global understanding of migratory patterns and destinations of <span class="hlt">Antarctic</span> blue whales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014DSRI...91..101B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014DSRI...91..101B"><span>Predictive habitat modelling of humpback (Megaptera novaeangliae) and <span class="hlt">Antarctic</span> minke (Balaenoptera bonaerensis) whales in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> as a planning tool for seismic surveys</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bombosch, Annette; Zitterbart, Daniel P.; Van Opzeeland, Ilse; Frickenhaus, Stephan; Burkhardt, Elke; Wisz, Mary S.; Boebel, Olaf</p> <p>2014-09-01</p> <p>Seismic surveys are frequently a matter of concern regarding their potentially negative impacts on marine mammals. In the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, which provides a critical habitat for several endangered cetacean species, seismic research activities are undertaken at a circumpolar scale. In order to minimize impacts of these surveys, pre-cruise planning requires detailed, spatio-temporally resolved knowledge on the likelihood of encountering these species in the survey area. In this publication we present predictive habitat modelling as a potential tool to support decisions for survey planning. We associated opportunistic sightings (2005-2011) of humpback (Megaptera novaeangliae, N=93) and <span class="hlt">Antarctic</span> minke whales (Balaenoptera bonaerensis, N=139) with a range of static and dynamic environmental variables. A maximum entropy algorithm (Maxent) was used to develop habitat models and to calculate daily basinwide/circumpolar prediction maps to evaluate how species-specific habitat conditions evolved throughout the spring and summer months. For both species, prediction maps revealed considerable changes in habitat suitability throughout the season. Suitable humpback whale habitat occurred predominantly in ice-free areas, expanding southwards with the retreating sea ice edge, whereas suitable <span class="hlt">Antarctic</span> minke whale habitat was consistently predicted within sea ice covered areas. Daily, large-scale prediction maps provide a valuable tool to design layout and timing of seismic surveys as they allow the identification and consideration of potential spatio-temporal hotspots to minimize potential impacts of seismic surveys on <span class="hlt">Antarctic</span> cetacean species.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMPP43B1345K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMPP43B1345K"><span><span class="hlt">Antarctic</span> Circumpolar Current Dynamics and Their Relation to <span class="hlt">Antarctic</span> Ice Sheet and Perennial Sea-Ice Variability in the Central Drake Passage During the Last Climate Cycle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kuhn, G.; Wu, S.; Hass, H. C.; Klages, J. P.; Zheng, X.; Arz, H. W.; Esper, O.; Hillenbrand, C. D.; Lange, C.; Lamy, F.; Lohmann, G.; Müller, J.; McCave, I. N. N.; Nürnberg, D.; Roberts, J.; Tiedemann, R.; Timmermann, A.; Titschack, J.; Zhang, X.</p> <p>2017-12-01</p> <p>The evolution of the <span class="hlt">Antarctic</span> Ice Sheet during the last climate cycle and the interrelation to global atmospheric and <span class="hlt">ocean</span> circulation remains controversial and plays an important role for our understanding of ice sheet response to modern global warming. The timing and sequence of deglacial warming is relevant for understanding the variability and sensitivity of the <span class="hlt">Antarctic</span> Ice Sheet to climatic changes, and the continuing rise of atmospheric greenhouse gas concentrations. The <span class="hlt">Antarctic</span> Ice Sheet is a pivotal component of the global water budget. Freshwater fluxes from the ice sheet may affect the <span class="hlt">Antarctic</span> Circumpolar Current (ACC), which is strongly impacted by the westerly wind belt in the <span class="hlt">Southern</span> Hemisphere (SHWW) and constricted to its narrowest extent in the Drake Passage. The flow of ACC water masses through Drake Passage is, therefore, crucial for advancing our understanding of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>'s role in global meridional overturning circulation and global climate change. In order to address orbital and millennial-scale variability of the <span class="hlt">Antarctic</span> ice sheet and the ACC, we applied a multi-proxy approach on a sediment core from the central Drake Passage including grain size, iceberg-rafted debris, mineral dust, bulk chemical and mineralogical composition, and physical properties. In combination with already published and new sediment records from the Drake Passage and Scotia Sea, as well as high-resolution data from <span class="hlt">Antarctic</span> ice cores (WDC, EDML), we now have evidence that during glacial times a more northerly extent of the perennial sea-ice zone decreased ACC current velocities in the central Drake Passage. During deglaciation the SHWW shifted southwards due to a decreasing temperature gradient between subtropical and polar latitudes caused by sea ice and ice sheet decline. This in turn caused <span class="hlt">Southern</span> Hemisphere warming, a more vigorous ACC, stronger <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ventilation, and warm Circumpolar Deep Water (CDW) upwelling on <span class="hlt">Antarctic</span> shelves</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ECSS..191..125S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ECSS..191..125S"><span>Phytoplankton community structure is influenced by seabird guano enrichment in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shatova, O. A.; Wing, S. R.; Hoffmann, L. J.; Wing, L. C.; Gault-Ringold, M.</p> <p>2017-05-01</p> <p>Phytoplankton biomass, productivity and community structure are strongly influenced by differences in nutrient concentrations among oceanographic water masses. Changes in community composition, particularly in the distribution of cell sizes, can result in dramatic changes in the energetics of pelagic food webs and ecosystem function in terms of biogeochemical cycling and carbon sequestration. Here we examine responses of natural phytoplankton communities from four major water masses in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> to enrichment from seabird guano, a concentrated source of bioactive metals (Mn, Fe, Co, Ni, Cu, Zn) and macronutrients (N, P), in a series of incubation experiments. Phytoplankton communities from sub-tropical water, modified sub-tropical water from the Snares Island wake, sub-<span class="hlt">Antarctic</span> water and <span class="hlt">Antarctic</span> water from the Ross Sea, each showed dramatic changes in community structure following additions of seabird guano. We observed particularly high growth of prymnesiophytes in response to the guano-derived nutrients within sub-<span class="hlt">Antarctic</span> and sub-tropical frontal zones, resulting in communities dominated by larger cell sizes than in control incubations. Community changes within treatments enriched with guano were distinct, and in most cases more extensive, than those observed for treatments with additions of macronutrients (N, P) or iron (Fe) alone. These results provide the first empirical evidence that seabird guano enrichment can drive significant changes in the structure and composition of natural phytoplankton communities. Our findings have important implications for understanding the consequences of accumulation of bioactive metals and macronutrients within food webs and the role of seabirds as nutrient vectors within the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ecosystem.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5673840','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5673840"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> Echinoids database – An updated version of <span class="hlt">Antarctic</span>, Sub-<span class="hlt">Antarctic</span> and cold temperate echinoid database</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Fabri-Ruiz, Salomé; Saucède, Thomas; Danis, Bruno; David, Bruno</p> <p>2017-01-01</p> <p>Abstract This database includes over 7,100 georeferenced occurrence records of sea urchins (Echinodermata: Echinoidea) obtained from samples collected in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (+180°W/+180°E; -35°/-78°S) during oceanographic cruises led over 150 years, from 1872 to 2015. Echinoids are common organisms of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> benthic communities. A total of 201 species is recorded, which display contrasting depth ranges and distribution patterns across austral provinces and bioregions. Echinoid species show various ecological traits including different nutrition and reproductive strategies. Information on taxonomy, sampling sites, and sampling sources are also made available. Environmental descriptors that are relevant to echinoid ecology are also made available for the study area (-180°W/+180°E; -45°/-78°S) and for the following decades: 1955–1964, 1965–1974, 1975–1984, 1985–1994 and 1995–2012. They were compiled from different sources and transformed to the same grid cell resolution of 0.1° per pixel. We also provide future projections for environmental descriptors established based on the Bio-Oracle database (Tyberghein et al. 2012). PMID:29134013</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27509536','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27509536"><span>Fate of Polycyclic Aromatic Hydrocarbons in Seawater from the Western Pacific to the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (17.5°N to 69.2°S) and Their Inventories on the <span class="hlt">Antarctic</span> Shelf.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cai, Minggang; Liu, Mengyang; Hong, Qingquan; Lin, Jing; Huang, Peng; Hong, Jiajun; Wang, Jun; Zhao, Wenlu; Chen, Meng; Cai, Minghong; Ye, Jun</p> <p>2016-09-06</p> <p>Semivolatile organic compounds such as polycyclic aromatic hydrocarbons (PAHs) have the potential to reach pristine environments through long-range transport. To investigate the long-range transport of the PAHs and their fate in <span class="hlt">Antarctic</span> seawater, dissolved PAHs in the surface waters from the western Pacific to the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (17.5°N to 69.2°S), as well as down to 3500 m PAH profiles in Prydz Bay and the adjacent <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, were observed during the 27th Chinese National <span class="hlt">Antarctic</span> Research Expedition in 2010. The concentrations of Σ9PAH in the surface seawater ranged from not detected (ND) to 21 ng L(-1), with a mean of 4.3 ng L(-1); and three-ring PAHs were the most abundant compounds. Samples close to the Australian mainland displayed the highest levels across the cruise. PAHs originated mainly from pyrogenic sources, such as grass, wood, and coal combustion. Vertical profiles of PAHs in Prydz Bay showed a maximum at a depth of 50 m and less variance with depth. In general, we inferred that the water masses as well as the phytoplankton were possible influencing factors on PAH surface-enrichment depth-depletion distribution. Inventory estimation highlighted the contribution of intermediate and deep seawater on storing PAHs in seawater from Prydz Bay, and suggested that climate change rarely shows the rapid release of the PAHs currently stored in the major reservoirs (intermediate and deep seawater).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23407538','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23407538"><span>Insolation-induced mid-Brunhes transition in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ventilation and deep-<span class="hlt">ocean</span> temperature.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yin, Qiuzhen</p> <p>2013-02-14</p> <p>Glacial-interglacial cycles characterized by long cold periods interrupted by short periods of warmth are the dominant feature of Pleistocene climate, with the relative intensity and duration of past and future interglacials being of particular interest for civilization. The interglacials after 430,000 years ago were characterized by warmer climates and higher atmospheric concentrations of carbon dioxide than the interglacials before, but the cause of this climatic transition (the so-called mid-Brunhes event (MBE)) is unknown. Here I show, on the basis of model simulations, that in response to insolation changes only, feedbacks between sea ice, temperature, evaporation and salinity caused vigorous pre-MBE <span class="hlt">Antarctic</span> bottom water formation and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ventilation. My results also show that strong westerlies increased the pre-MBE overturning in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> via an increased latitudinal insolation gradient created by changes in eccentricity during austral winter and by changes in obliquity during austral summer. The stronger bottom water formation led to a cooler deep <span class="hlt">ocean</span> during the older interglacials. These insolation-induced differences in the deep-sea temperature and in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ventilation between the more recent interglacials and the older ones were not expected, because there is no straightforward systematic difference in the astronomical parameters between the interglacials before and after 430,000 years ago. Rather than being a real 'event', the apparent MBE seems to have resulted from a series of individual interglacial responses--including notable exceptions to the general pattern--to various combinations of insolation conditions. Consequently, assuming no anthropogenic interference, future interglacials may have pre- or post-MBE characteristics without there being a systematic change in forcings. These findings are a first step towards understanding the magnitude change of the interglacial carbon dioxide concentration around 430</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFMOS33A1684H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFMOS33A1684H"><span>Habitat Selection and Foraging Behavior of <span class="hlt">Southern</span> Elephant Seals in the Western <span class="hlt">Antarctic</span> Peninsula</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huckstadt, L.; Costa, D. P.; McDonald, B. I.; Tremblay, Y.; Crocker, D. E.; Goebel, M. E.; Fedak, M. E.</p> <p>2006-12-01</p> <p>We examined the foraging behavior of 18 <span class="hlt">southern</span> elephant seals foraging over two seasons in the Western <span class="hlt">Antarctic</span> Peninsula. The foraging behavior and habitat utilization of 7 females in 2005 and 12 in 2006 were followed using satellite linked Satellite Relay Data Loggers that measured diving behavior as well collected salinity and temperature profiles as the animals dove. Animals were tagged after the annual molt during February at Cape Shirreff Livngston Island, South Shetland Islands. There was significant interannual variation in the regions of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> used by seals from Livingston Island. In 2005 of the 7 animals tagged one foraged 4700 km due west of the <span class="hlt">Antarctic</span> Peninsula going as far as 150 W. The remaining females headed south along the Western <span class="hlt">Antarctic</span> Peninsula bypassing Marguerite Bay moving south along Alexander Island. Three of these animals continued to forage in the pack ice as it developed. On their return trip all females swam past Livingston Island, continuing on to South Georgia Island where they apparently bred in the austral spring. One animal returned to Cape Shirreff to molt and her tag was recovered. During 2006 animals initially followed a similar migratory pattern going south along the <span class="hlt">Antarctic</span> Peninsula, but unlike 2005 where the majority of the animals remained in the immediate vicinity of the Western <span class="hlt">Antarctic</span> Peninsula, most of the animals in 2006 moved well to the west foraging as far as the Amundsen Sea. We compared the area restricted search (focal foraging areas) areas of these animals using a newly developed fractal landscape technique that identifies and quantifies areas of intensive search. The fractal analysis of area restricted search shows that the area, distance and coverage (Fractal D) searched were not different between years, while the time spent in the search areas was higher in 2005. Further analysis will examine how the physical properties of the water column as determined from the CTD data derived from</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21115838','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21115838"><span><span class="hlt">Antarctic</span> lakes suggest millennial reorganizations of <span class="hlt">Southern</span> Hemisphere atmospheric and <span class="hlt">oceanic</span> circulation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hall, Brenda L; Denton, George H; Fountain, Andrew G; Hendy, Chris H; Henderson, Gideon M</p> <p>2010-12-14</p> <p>The phasing of millennial-scale oscillations in Antarctica relative to those elsewhere in the world is important for discriminating among models for abrupt climate change, particularly those involving the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. However, records of millennial-scale variability from Antarctica dating to the last glacial maximum are rare and rely heavily on data from widely spaced ice cores, some of which show little variability through that time. Here, we present new data from closed-basin lakes in the Dry Valleys region of East Antarctica that show high-magnitude, high-frequency oscillations in surface level during the late Pleistocene synchronous with climate fluctuations elsewhere in the <span class="hlt">Southern</span> Hemisphere. These data suggest a coherent <span class="hlt">Southern</span> Hemisphere pattern of climate change on millennial time scales, at least in the Pacific sector, and indicate that any hypothesis concerning the origin of these events must account for synchronous changes in both high and temperate latitudes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3003093','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3003093"><span><span class="hlt">Antarctic</span> lakes suggest millennial reorganizations of <span class="hlt">Southern</span> Hemisphere atmospheric and <span class="hlt">oceanic</span> circulation</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hall, Brenda L.; Denton, George H.; Fountain, Andrew G.; Hendy, Chris H.; Henderson, Gideon M.</p> <p>2010-01-01</p> <p>The phasing of millennial-scale oscillations in Antarctica relative to those elsewhere in the world is important for discriminating among models for abrupt climate change, particularly those involving the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. However, records of millennial-scale variability from Antarctica dating to the last glacial maximum are rare and rely heavily on data from widely spaced ice cores, some of which show little variability through that time. Here, we present new data from closed-basin lakes in the Dry Valleys region of East Antarctica that show high-magnitude, high-frequency oscillations in surface level during the late Pleistocene synchronous with climate fluctuations elsewhere in the <span class="hlt">Southern</span> Hemisphere. These data suggest a coherent <span class="hlt">Southern</span> Hemisphere pattern of climate change on millennial time scales, at least in the Pacific sector, and indicate that any hypothesis concerning the origin of these events must account for synchronous changes in both high and temperate latitudes. PMID:21115838</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFMOS13C1208P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFMOS13C1208P"><span>Tidal Impacts on Oceanographic and Sea-ice Processes in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Padman, L.; Muench, R. D.; Howard, S.; Mueller, R.</p> <p>2008-12-01</p> <p>We review recent field and modeling results that demonstrate the importance of tides in establishing the oceanographic and sea-ice conditions in the boundary regions of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. The tidal component dominates the total <span class="hlt">oceanic</span> kinetic energy throughout much of the circum-<span class="hlt">Antarctic</span> seas. This domination is especially pronounced over the continental slope and shelf including the sub-ice-shelf cavities. Tides provide most of the energy that forces diapycnal mixing under ice shelves and thereby contributes to basal melting. The resulting Ice Shelf Water is a significant component of the <span class="hlt">Antarctic</span> Bottom Water (AABW) filling much of the deep global <span class="hlt">ocean</span>. Tides exert significant divergent forcing on sea ice along glacial ice fronts and coastal regions, contributing to creation and maintenance of the coastal polynyas where much of the High Salinity Shelf Water component of AABW is formed. Additional tidally forced ice divergence along the shelf break and upper slope significantly impacts area-averaged ice growth and upper-<span class="hlt">ocean</span> salinity. Tidally forced cross- slope advection, and mixing by the benthic stress associated with tidal currents along the shelf break and upper slope, strongly influence the paths, volume fluxes and hydrographic properties of benthic outflows of dense water leaving the continental shelf. These outflows provide primary source waters for the AABW. These results confirm that general <span class="hlt">ocean</span> circulation and coupled <span class="hlt">ocean</span>/ice/atmosphere climate models must incorporate the impacts of tides.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3721125','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3721125"><span>Secondary organic aerosols over <span class="hlt">oceans</span> via oxidation of isoprene and monoterpenes from Arctic to <span class="hlt">Antarctic</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hu, Qi-Hou; Xie, Zhou-Qing; Wang, Xin-Ming; Kang, Hui; He, Quan-Fu; Zhang, Pengfei</p> <p>2013-01-01</p> <p>Isoprene and monoterpenes are important precursors of secondary organic aerosols (SOA) in continents. However, their contributions to aerosols over <span class="hlt">oceans</span> are still inconclusive. Here we analyzed SOA tracers from isoprene and monoterpenes in aerosol samples collected over <span class="hlt">oceans</span> during the Chinese Arctic and <span class="hlt">Antarctic</span> Research Expeditions. Combined with literature reports elsewhere, we found that the dominant tracers are the oxidation products of isoprene. The concentrations of tracers varied considerably. The mean average values were approximately one order of magnitude higher in the Northern Hemisphere than in the <span class="hlt">Southern</span> Hemisphere. High values were generally observed in coastal regions. This phenomenon was ascribed to the outflow influence from continental sources. High levels of isoprene could emit from <span class="hlt">oceans</span> and consequently have a significant impact on marine SOA as inferred from isoprene SOA during phytoplankton blooms, which may abruptly increase up to 95 ng/m3 in the boundary layer over remote <span class="hlt">oceans</span>. PMID:23880782</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3742792','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3742792"><span>Seasonal and Geographic Variation of <span class="hlt">Southern</span> Blue Whale Subspecies in the Indian <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Samaran, Flore; Stafford, Kathleen M.; Branch, Trevor A.; Gedamke, Jason; Royer, Jean-Yves; Dziak, Robert P.; Guinet, Christophe</p> <p>2013-01-01</p> <p>Understanding the seasonal movements and distribution patterns of migratory species over <span class="hlt">ocean</span> basin scales is vital for appropriate conservation and management measures. However, assessing populations over remote regions is challenging, particularly if they are rare. Blue whales (Balaenoptera musculus spp) are an endangered species found in the <span class="hlt">Southern</span> and Indian <span class="hlt">Oceans</span>. Here two recognized subspecies of blue whales and, based on passive acoustic monitoring, four “acoustic populations” occur. Three of these are pygmy blue whale (B.m. brevicauda) populations while the fourth is the <span class="hlt">Antarctic</span> blue whale (B.m. intermedia). Past whaling catches have dramatically reduced their numbers but recent acoustic recordings show that these <span class="hlt">oceans</span> are still important habitat for blue whales. Presently little is known about the seasonal movements and degree of overlap of these four populations, particularly in the central Indian <span class="hlt">Ocean</span>. We examined the geographic and seasonal occurrence of different blue whale acoustic populations using one year of passive acoustic recording from three sites located at different latitudes in the Indian <span class="hlt">Ocean</span>. The vocalizations of the different blue whale subspecies and acoustic populations were recorded seasonally in different regions. For some call types and locations, there was spatial and temporal overlap, particularly between <span class="hlt">Antarctic</span> and different pygmy blue whale acoustic populations. Except on the southernmost hydrophone, all three pygmy blue whale acoustic populations were found at different sites or during different seasons, which further suggests that these populations are generally geographically distinct. This unusual blue whale diversity in sub-<span class="hlt">Antarctic</span> and sub-tropical waters indicates the importance of the area for blue whales in these former whaling grounds. PMID:23967221</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040015192&hterms=Parkinsons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DParkinsons','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040015192&hterms=Parkinsons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DParkinsons"><span>Observed and Modeled Trends in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Sea Ice</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Parkinson, Claire L.</p> <p>2003-01-01</p> <p>Conceptual models and global climate model (GCM) simulations have both indicated the likelihood of an enhanced sensitivity to climate change in the polar regions, derived from the positive feedbacks brought about by the polar abundance of snow and ice surfaces. Some models further indicate that the changes in the polar regions can have a significant impact globally. For instance, 37% of the temperature sensitivity to a doubling of atmospheric CO2 in simulations with the GCM of the Goddard Institute for Space Studies (GISS) is attributable exclusively to inclusion of sea ice variations in the model calculations. Both sea ice thickness and sea ice extent decrease markedly in the doubled CO, case, thereby allowing the ice feedbacks to occur. Stand-alone sea ice models have shown <span class="hlt">Southern</span> <span class="hlt">Ocean</span> hemispherically averaged winter ice-edge retreats of 1.4 deg latitude for each 1 K increase in atmospheric temperatures. Observations, however, show a much more varied <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ice cover, both spatially and temporally, than many of the modeled expectations. In fact, the satellite passive-microwave record of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> sea ice since late 1978 has revealed overall increases rather than decreases in ice extents, with ice extent trends on the order of 11,000 sq km/year. When broken down spatially, the positive trends are strongest in the Ross Sea, while the trends are negative in the Bellingshausen/Amundsen Seas. Greater spatial detail can be obtained by examining trends in the length of the sea ice season, and those trends show a coherent picture of shortening sea ice seasons throughout almost the entire Bellingshausen and Amundsen Seas to the west of the <span class="hlt">Antarctic</span> Peninsula and in the far western Weddell Sea immediately to the east of the Peninsula, with lengthening sea ice seasons around much of the rest of the continent. This pattern corresponds well with the spatial pattern of temperature trends, as the Peninsula region is the one region in the <span class="hlt">Antarctic</span> with a strong</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRC..119.5690K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRC..119.5690K"><span>Pathways of basal meltwater from <span class="hlt">Antarctic</span> ice shelves: A model study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kusahara, Kazuya; Hasumi, Hiroyasu</p> <p>2014-09-01</p> <p>We investigate spreading pathways of basal meltwater released from all <span class="hlt">Antarctic</span> ice shelves using a circumpolar coupled ice shelf-sea ice-<span class="hlt">ocean</span> model that reproduces major features of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> circulation, including the <span class="hlt">Antarctic</span> Circumpolar Current (ACC). Several independent virtual tracers are used to identify detailed pathways of basal meltwaters. The spreading pathways of the meltwater tracers depend on formation sites, because the meltwaters are transported by local ambient <span class="hlt">ocean</span> circulation. Meltwaters from ice shelves in the Weddell and Amundsen-Bellingshausen Seas in surface/subsurface layers are effectively advected to lower latitudes with the ACC. Although a large portion of the basal meltwaters is present in surface and subsurface layers, a part of the basal meltwaters penetrates into the bottom layer through active dense water formation along the <span class="hlt">Antarctic</span> coastal margins. The signals at the seafloor extend along the topography, showing a horizontal distribution similar to the observed spreading of <span class="hlt">Antarctic</span> Bottom Water. Meltwaters originating from ice shelves in the Weddell and Ross Seas and in the Indian sector significantly contribute to the bottom signals. A series of numerical experiments in which thermodynamic interaction between the ice shelf and <span class="hlt">ocean</span> is neglected regionally demonstrates that the basal meltwater of each ice shelf impacts sea ice and/or <span class="hlt">ocean</span> thermohaline circulation in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. This article was corrected on 10 OCT 2014. See the end of the full text for details.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010DSRI...57..469P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010DSRI...57..469P"><span>Spatial and seasonal distribution of adult Oithona similis in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>: Predictions using boosted regression trees</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pinkerton, Matt H.; Smith, Adam N. H.; Raymond, Ben; Hosie, Graham W.; Sharp, Ben; Leathwick, John R.; Bradford-Grieve, Janet M.</p> <p>2010-04-01</p> <p>We applied a multivariate statistical modelling technique called boosted regression trees to derive relationships between environmental conditions and the distribution of the adult stage of the cyclopoid copepod Oithona similis in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Nearly 20 000 samples from the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Continuous Plankton Recorder survey (87% from East Antarctica) were used to model the probability of detection (presence) and relative abundance of adults of this zooplankton species in surface waters. We demonstrate that it is possible to obtain reasonable models for both the presence (area under the Receiver Operating Characteristic curve of 0.77) and relative abundance (28-35% variance explained) of adult O. similis between November and March in much of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. No investigation was possible where the environmental characteristics were not well represented by the SO-CPR dataset, namely, the Argentine shelf, Weddell Sea, and the frontal region north of the Amundsen Sea, or under sea-ice. Our analyses support the hypothesis that adult O. similis abundance is related to environmental conditions in a broadly similar way throughout the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Compared to a compilation of net-haul data from the literature, the abundance model explained 34% of the variance in surface concentrations of adult stages of this species, and 23-59% of the variance in depth-integrated abundance of copepodite and adult stages combined. The models show higher occurrence and elevated abundances in a broad circumpolar band between the <span class="hlt">Antarctic</span> Polar Front and the <span class="hlt">southern</span> boundary of the <span class="hlt">Antarctic</span> Circumpolar Current (approximately 54-64°S). Evidence of diel vertical migration by adults of this species north of 65°S was found, with surface abundances 20% higher at night than during the day. There was no evidence of diel migration south of 65°S. Five potential "hotspots" of adult O. similis were identified: in the <span class="hlt">southern</span> Scotia Sea, two areas off east Antarctica, in the frontal</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016FrES...10..479J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016FrES...10..479J"><span>Satellite remote sensing of the island mass effect on the Sub-<span class="hlt">Antarctic</span> Kerguelen Plateau, <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jena, Babula</p> <p>2016-09-01</p> <p>The presence of the Kerguelen Plateau and surrounding bathymetric features has a strong influence on the persistently eastward flowing <span class="hlt">Antarctic</span> Circumpolar Current (ACC), resulting in enhancement of surface chlorophyll-a (Chl- a) in the downstream section of the plateau along the polar front (PF). The phenomenon is reported in this paper as the island mass effect (IME). Analysis of climatological Chl- a datasets from Aqua- Moderate Resolution Imaging Spectroradiometer (Aqua- MODIS) and Sea-viewing Wide Field-of-view Sensor (SeaWiFS) shows distinct bloomy plumes (Chl- a>0.5 mg/m3) during austral spring-summer spreading as far as ~1800 km offshore up to 98°E along the downstream of the north Kerguelen Plateau (NKP). Similar IME phenomena is apparent over the south Kerguelen Plateau (SKP) with the phytoplankton bloom extending up to 96.7°E, along the <span class="hlt">southern</span> boundary of ACC. The IME phenomena are pronounced only during austral spring-summer period with the availability of light and sedimentary source of iron from shallow plateau to sea surface that fertilizes the mixed layer. The NKP bloom peaks with a maximum areal extent of 1.315 million km2 during December, and the SKP bloom peaks during January with a time lag of one month. The blooms exist for at least 4 months of a year and are significant both as the base of regional food web and for regulating the biogeochemical cycle in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Even though the surface water above the Kerguelen Plateau is rich in Chl- a, an exception of an oligotrophic condition dominated between NKP and SKP due to apparent intrusion of iron limited low phytoplankton regime waters from the Enderby basin through the northeastward Fawn Trough Current.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GBioC..31.1420S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GBioC..31.1420S"><span>Stirring Up the Biological Pump: Vertical Mixing and Carbon Export in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stukel, Michael R.; Ducklow, Hugh W.</p> <p>2017-09-01</p> <p>The biological carbon pump (BCP) transports organic carbon from the surface to the <span class="hlt">ocean</span>'s interior via sinking particles, vertically migrating organisms, and passive transport of organic matter by advection and diffusion. While many studies have quantified sinking particles, the magnitude of passive transport remains poorly constrained. In the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> weak thermal stratification, strong vertical gradients in particulate organic matter, and weak vertical nitrate gradients suggest that passive transport from the euphotic zone may be particularly important. We compile data from seasonal time series at a coastal site near Palmer Station, annual regional cruises in the Western <span class="hlt">Antarctic</span> Peninsula (WAP), cruises throughout the broader <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, and SOCCOM (<span class="hlt">Southern</span> <span class="hlt">Ocean</span> Carbon and Climate Observations and Modeling) autonomous profiling floats to estimate spatial and temporal patterns in vertical gradients of nitrate, particulate nitrogen (PN), and dissolved organic carbon. Under a steady state approximation, the ratio of ∂PN/∂z to ∂NO3-/∂z suggests that passive transport of PN may be responsible for removing 46% (37%-58%) of the nitrate introduced into the surface <span class="hlt">ocean</span> of the WAP (with dissolved organic matter contributing an additional 3-6%) and for 23% (19%-28%) of the BCP in the broader <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. A simple model parameterized with in situ nitrate, PN, and primary production data suggested that passive transport was responsible for 54% of the magnitude of the BCP in the WAP. Our results highlight the potential importance of passive transport (by advection and diffusion) of organic matter in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> but should only be considered indicative of high passive transport (rather than conclusive evidence) due to our steady state assumptions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ACP....16.2185H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ACP....16.2185H"><span>Unexpectedly high ultrafine aerosol concentrations above East <span class="hlt">Antarctic</span> sea ice</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Humphries, R. S.; Klekociuk, A. R.; Schofield, R.; Keywood, M.; Ward, J.; Wilson, S. R.</p> <p>2016-02-01</p> <p>Better characterisation of aerosol processes in pristine, natural environments, such as Antarctica, have recently been shown to lead to the largest reduction in uncertainties in our understanding of radiative forcing. Our understanding of aerosols in the <span class="hlt">Antarctic</span> region is currently based on measurements that are often limited to boundary layer air masses at spatially sparse coastal and continental research stations, with only a handful of studies in the vast sea-ice region. In this paper, the first observational study of sub-micron aerosols in the East <span class="hlt">Antarctic</span> sea ice region is presented. Measurements were conducted aboard the icebreaker Aurora Australis in spring 2012 and found that boundary layer condensation nuclei (CN3) concentrations exhibited a five-fold increase moving across the polar front, with mean polar cell concentrations of 1130 cm-3 - higher than any observed elsewhere in the <span class="hlt">Antarctic</span> and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> region. The absence of evidence for aerosol growth suggested that nucleation was unlikely to be local. Air parcel trajectories indicated significant influence from the free troposphere above the <span class="hlt">Antarctic</span> continent, implicating this as the likely nucleation region for surface aerosol, a similar conclusion to previous <span class="hlt">Antarctic</span> aerosol studies. The highest aerosol concentrations were found to correlate with low-pressure systems, suggesting that the passage of cyclones provided an accelerated pathway, delivering air masses quickly from the free troposphere to the surface. After descent from the <span class="hlt">Antarctic</span> free troposphere, trajectories suggest that sea-ice boundary layer air masses travelled equatorward into the low-albedo <span class="hlt">Southern</span> <span class="hlt">Ocean</span> region, transporting with them emissions and these aerosol nuclei which, after growth, may potentially impact on the region's radiative balance. The high aerosol concentrations and their transport pathways described here, could help reduce the discrepancy currently present between simulations and observations of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24802817','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24802817"><span>Climate change and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ecosystems I: how changes in physical habitats directly affect marine biota.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Constable, Andrew J; Melbourne-Thomas, Jessica; Corney, Stuart P; Arrigo, Kevin R; Barbraud, Christophe; Barnes, David K A; Bindoff, Nathaniel L; Boyd, Philip W; Brandt, Angelika; Costa, Daniel P; Davidson, Andrew T; Ducklow, Hugh W; Emmerson, Louise; Fukuchi, Mitsuo; Gutt, Julian; Hindell, Mark A; Hofmann, Eileen E; Hosie, Graham W; Iida, Takahiro; Jacob, Sarah; Johnston, Nadine M; Kawaguchi, So; Kokubun, Nobuo; Koubbi, Philippe; Lea, Mary-Anne; Makhado, Azwianewi; Massom, Rob A; Meiners, Klaus; Meredith, Michael P; Murphy, Eugene J; Nicol, Stephen; Reid, Keith; Richerson, Kate; Riddle, Martin J; Rintoul, Stephen R; Smith, Walker O; Southwell, Colin; Stark, Jonathon S; Sumner, Michael; Swadling, Kerrie M; Takahashi, Kunio T; Trathan, Phil N; Welsford, Dirk C; Weimerskirch, Henri; Westwood, Karen J; Wienecke, Barbara C; Wolf-Gladrow, Dieter; Wright, Simon W; Xavier, Jose C; Ziegler, Philippe</p> <p>2014-10-01</p> <p><span class="hlt">Antarctic</span> and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (ASO) marine ecosystems have been changing for at least the last 30 years, including in response to increasing <span class="hlt">ocean</span> temperatures and changes in the extent and seasonality of sea ice; the magnitude and direction of these changes differ between regions around Antarctica that could see populations of the same species changing differently in different regions. This article reviews current and expected changes in ASO physical habitats in response to climate change. It then reviews how these changes may impact the autecology of marine biota of this polar region: microbes, zooplankton, salps, <span class="hlt">Antarctic</span> krill, fish, cephalopods, marine mammals, seabirds, and benthos. The general prognosis for ASO marine habitats is for an overall warming and freshening, strengthening of westerly winds, with a potential pole-ward movement of those winds and the frontal systems, and an increase in <span class="hlt">ocean</span> eddy activity. Many habitat parameters will have regionally specific changes, particularly relating to sea ice characteristics and seasonal dynamics. Lower trophic levels are expected to move south as the <span class="hlt">ocean</span> conditions in which they are currently found move pole-ward. For <span class="hlt">Antarctic</span> krill and finfish, the latitudinal breadth of their range will depend on their tolerance of warming <span class="hlt">oceans</span> and changes to productivity. <span class="hlt">Ocean</span> acidification is a concern not only for calcifying organisms but also for crustaceans such as <span class="hlt">Antarctic</span> krill; it is also likely to be the most important change in benthic habitats over the coming century. For marine mammals and birds, the expected changes primarily relate to their flexibility in moving to alternative locations for food and the energetic cost of longer or more complex foraging trips for those that are bound to breeding colonies. Few species are sufficiently well studied to make comprehensive species-specific vulnerability assessments possible. Priorities for future work are discussed. © 2014 John Wiley & Sons Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29791031','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29791031"><span><span class="hlt">Ocean</span> acidification stimulates particulate organic carbon accumulation in two <span class="hlt">Antarctic</span> diatom species under moderate and high natural solar radiation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Heiden, Jasmin P; Thoms, Silke; Bischof, Kai; Trimborn, Scarlett</p> <p>2018-05-23</p> <p>Impacts of rising atmospheric CO 2 concentrations and increased daily irradiances from enhanced surface water stratification on phytoplankton physiology in the coastal <span class="hlt">Southern</span> <span class="hlt">Ocean</span> remain still unclear. Therefore, in the two <span class="hlt">Antarctic</span> diatoms Fragilariopsis curta and Odontella weissflogii the effects of moderate and high natural solar radiation combined with either ambient or future pCO 2 on cellular particulate organic carbon (POC) contents and photophysiology were investigated. Results showed that increasing CO 2 concentrations had greater impacts on diatom physiology than exposure to increasing solar radiation. Irrespective of the applied solar radiation regime, cellular POC quotas increased with future pCO 2 in both diatoms. Lowered maximum quantum yields of photochemistry in PSII (F v /F m ) indicated a higher photosensitivity under these conditions, being counteracted by increased cellular concentrations of functional photosynthetic reaction centers. Overall, our results suggest that both bloom-forming <span class="hlt">Antarctic</span> coastal diatoms might increase carbon contents under future pCO 2 conditions despite reduced physiological fitness. This indicates a higher potential for primary productivity by the two diatom species with important implications for the CO 2 sequestration potential of diatom communities in the future coastal <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRC..12210042B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRC..12210042B"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> Mixed-Layer Seasonal and Interannual Variations From Combined Satellite and In Situ Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Buongiorno Nardelli, B.; Guinehut, S.; Verbrugge, N.; Cotroneo, Y.; Zambianchi, E.; Iudicone, D.</p> <p>2017-12-01</p> <p>The depth of the upper <span class="hlt">ocean</span> mixed layer provides fundamental information on the amount of seawater that directly interacts with the atmosphere. Its space-time variability modulates water mass formation and carbon sequestration processes related to both the physical and biological pumps. These processes are particularly relevant in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, where surface mixed-layer depth estimates are generally obtained either as climatological fields derived from in situ observations or through numerical simulations. Here we demonstrate that weekly observation-based reconstructions can be used to describe the variations of the mixed-layer depth in the upper <span class="hlt">ocean</span> over a range of space and time scales. We compare and validate four different products obtained by combining satellite measurements of the sea surface temperature, salinity, and dynamic topography and in situ Argo profiles. We also compute an ensemble mean and use the corresponding spread to estimate mixed-layer depth uncertainties and to identify the more reliable products. The analysis points out the advantage of synergistic approaches that include in input the sea surface salinity observations obtained through a multivariate optimal interpolation. Corresponding data allow to assess mixed-layer depth seasonal and interannual variability. Specifically, the maximum correlations between mixed-layer anomalies and the <span class="hlt">Southern</span> Annular Mode are found at different time lags, related to distinct summer/winter responses in the <span class="hlt">Antarctic</span> Intermediate Water and Sub-<span class="hlt">Antarctic</span> Mode Waters main formation areas.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070035051','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070035051"><span>The Influence of Sea Ice on Primary Production in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>: A Satellite Perspective</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smith, Walker O., Jr.; Comiso, Josefino C.</p> <p>2007-01-01</p> <p>Sea ice in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is a major controlling factor on phytoplankton productivity and growth, but the relationship is modified by regional differences in atmospheric and oceanographic conditions. We used the phytoplankton biomass (binned at 7-day intervals), PAR and cloud cover data from SeaWiFS, ice concentrations data from SSM/I and AMSR-E, and sea-surface temperature data from AVHRR, in combination with a vertically integrated model to estimate primary productivity throughout the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (south of 60"s). We also selected six areas within the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and analyzed the variability of the primary productivity and trends through time, as well as the relationship of sea ice to productivity. We found substantial interannual variability in productivity from 1997 - 2005 in all regions of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, and this variability appeared to be driven in large part by ice dynamics. The most productive regions of <span class="hlt">Antarctic</span> waters were the continental shelves, which showed the earliest growth, the maximum biomass, and the greatest areal specific productivity. In contrast, no large, sustained blooms occurred in waters of greater depth (> 1,000 m). We suggest that this is due to the slightly greater mixed layer depths found in waters off the continental shelf, and that the interactive effects of iron and irradiance (that is, increased iron requirements in low irradiance environments) result in the limitation of phytoplankton biomass over large regions of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009DSRI...56.2013B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009DSRI...56.2013B"><span>Bathymetric distribution patterns of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> macrofaunal taxa: Bivalvia, Gastropoda, Isopoda and Polychaeta</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brandt, Angelika; Linse, Katrin; Schüller, Myriam</p> <p>2009-11-01</p> <p>The aim of this study is to compare the depth distributions of four major <span class="hlt">Southern</span> <span class="hlt">Ocean</span> macrobenthic epi- and infaunal taxa, the Bivalvia, Gastropoda, Isopoda, and Polychaeta, from subtidal to abyssal depth. All literature data up to summer 2008, as well as the unpublished data from the most recent ANDEEP I-III (<span class="hlt">Antarctic</span> benthic deep-sea biodiversity: colonisation history and recent community patterns) expeditions to the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> deep sea are included in the analysis. Benthic invertebrates in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> are known for their wide bathymetric ranges. We analysed the distributions of four of the most abundant and species-rich taxa from intertidal to abyssal (5200 m) depths in depth zones of 100 m. The depth distributions of three macrofaunal classes (Bivalvia, Gastropoda, Polychaeta) and one order (Isopoda) showed distinct differences. In the case of bivalves, gastropods and polychaetes, the number of species per depth zone decreased from the shelf to the slope at around 1000 m depth and then showed stable low numbers. The isopods showed the opposite trend; they were less species rich in the upper 1000 m but increased in species numbers from the slope to bathyal and abyssal depths. Depth ranges of families of the studied taxa (Bivalvia: 31 families, Gastropoda: 60, Isopoda: 32, and Polychaeta: 46 families) were compiled and illustrated. At present vast areas of the deep sea in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> remain unexplored and species accumulation curves showed that only a fraction of the species have been discovered to date. We anticipate that further investigations will greatly increase the number of species known in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> deep sea.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010114461','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010114461"><span>Modeling UV-B Effects on Primary Production Throughout the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Using Multi-Sensor Satellite Data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lubin, Dan</p> <p>2001-01-01</p> <p>This study has used a combination of <span class="hlt">ocean</span> color, backscattered ultraviolet, and passive microwave satellite data to investigate the impact of the springtime <span class="hlt">Antarctic</span> ozone depletion on the base of the <span class="hlt">Antarctic</span> marine food web - primary production by phytoplankton. Spectral ultraviolet (UV) radiation fields derived from the satellite data are propagated into the water column where they force physiologically-based numerical models of phytoplankton growth. This large-scale study has been divided into two components: (1) the use of Total Ozone Mapping Spectrometer (TOMS) and Special Sensor Microwave Imager (SSM/I) data in conjunction with radiative transfer theory to derive the surface spectral UV irradiance throughout the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>; and (2) the merging of these UV irradiances with the climatology of chlorophyll derived from SeaWiFS data to specify the input data for the physiological models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950036299&hterms=ren&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dren','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950036299&hterms=ren&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dren"><span>On the role of the <span class="hlt">Antarctic</span> continent in forcing large-scale circulations in the high <span class="hlt">southern</span> latitudes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Parish, Thomas R.; Bromwich, David H.; Tzeng, Ren-Yow</p> <p>1994-01-01</p> <p>The <span class="hlt">Antarctic</span> topography and attendant katabatic wind regime appear to play a key role in the climate of the high <span class="hlt">southern</span> latitudes. During the nonsummer months, persistent and often times intense katabatic winds occur in the lowest few hundred meters of the <span class="hlt">Antarctic</span> atmosphere. These slope flows transport significant amounts of cold air northward and thereby modify the horizontal pressure field over the high <span class="hlt">southern</span> latitudes. Three-year seasonal cycle numerical simulations using the NCAR Community Climate Model Version 1 (CCM1) with and without representation of the <span class="hlt">Antarctic</span> orography were performed to explore the role of the elevated terrain and drainage flows on the distribution and evolution of the horizontal pressure field. The katabatic wind regime is an important part of a clearly defined mean meridional circulation in the high <span class="hlt">southern</span> latitudes. The position and intensity of the attendant sea level low pressure belt appears to be tied to the <span class="hlt">Antarctic</span> orography. The seasonal movement of mass in the high <span class="hlt">southern</span> latitudes is therefore constrained by the presence of the <span class="hlt">Antarctic</span> ice sheet. The semiannual oscillation of pressure over Antarctica and the high <span class="hlt">southern</span> latitutdes is well depicted in the CCM1 only when the <span class="hlt">Antarctic</span> orography is included.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeoRL..41.7950S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeoRL..41.7950S"><span>Observations of a diapycnal shortcut to adiabatic upwelling of <span class="hlt">Antarctic</span> Circumpolar Deep Water</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Silvester, J. Mead; Lenn, Yueng-Djern; Polton, Jeff A.; Rippeth, Tom P.; Maqueda, M. Morales</p> <p>2014-11-01</p> <p>In the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, small-scale turbulence causes diapycnal mixing which influences important water mass transformations, in turn impacting large-scale <span class="hlt">ocean</span> transports such as the Meridional Overturning Circulation (MOC), a key controller of Earth's climate. We present direct observations of mixing over the <span class="hlt">Antarctic</span> continental slope between water masses that are part of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> MOC. A 12 h time series of microstructure turbulence measurements, hydrography, and velocity observations off Elephant Island, north of the <span class="hlt">Antarctic</span> Peninsula, reveals two concurrent bursts of elevated dissipation of O(10-6) W kg-1, resulting in heat fluxes ˜10 times higher than basin-integrated Drake Passage estimates. This occurs across the boundary between adjacent adiabatic upwelling and downwelling overturning cells. Ray tracing to nearby topography shows mixing between 300 and 400 m is consistent with the breaking of locally generated internal tidal waves. Since similar conditions extend to much of the <span class="hlt">Antarctic</span> continental slope where these water masses outcrop, diapycnal mixing may contribute significantly to upwelling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3404021','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3404021"><span>Diversity and Distribution Patterns in High <span class="hlt">Southern</span> Latitude Sponges</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Downey, Rachel V.; Griffiths, Huw J.; Linse, Katrin; Janussen, Dorte</p> <p>2012-01-01</p> <p>Sponges play a key role in <span class="hlt">Antarctic</span> marine benthic community structure and dynamics and are often a dominant component of many <span class="hlt">Southern</span> <span class="hlt">Ocean</span> benthic communities. Understanding the drivers of sponge distribution in Antarctica enables us to understand many of general benthic biodiversity patterns in the region. The sponges of the <span class="hlt">Antarctic</span> and neighbouring oceanographic regions were assessed for species richness and biogeographic patterns using over 8,800 distribution records. Species-rich regions include the <span class="hlt">Antarctic</span> Peninsula, South Shetland Islands, South Georgia, Eastern Weddell Sea, Kerguelen Plateau, Falkland Islands and north New Zealand. Sampling intensity varied greatly within the study area, with sampling hotspots found at the <span class="hlt">Antarctic</span> Peninsula, South Georgia, north New Zealand and Tierra del Fuego, with limited sampling in the Bellingshausen and Amundsen seas in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. In contrast to previous studies we found that eurybathy and circumpolar distributions are important but not dominant characteristics in <span class="hlt">Antarctic</span> sponges. Overall <span class="hlt">Antarctic</span> sponge species endemism is ∼43%, with a higher level for the class Hexactinellida (68%). Endemism levels are lower than previous estimates, but still indicate the importance of the Polar Front in isolating the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> fauna. Nineteen distinct sponge distribution patterns were found, ranging from regional endemics to cosmopolitan species. A single, distinct <span class="hlt">Antarctic</span> demosponge fauna is found to encompass all areas within the Polar Front, and the sub-<span class="hlt">Antarctic</span> regions of the Kerguelen Plateau and Macquarie Island. Biogeographical analyses indicate stronger faunal links between Antarctica and South America, with little evidence of links between Antarctica and South Africa, <span class="hlt">Southern</span> Australia or New Zealand. We conclude that the biogeographic and species distribution patterns observed are largely driven by the <span class="hlt">Antarctic</span> Circumpolar Current and the timing of past continent connectivity. PMID</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMOS42A..08S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMOS42A..08S"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> Carbon Dioxide and Oxygen Fluxes Detected by SOCCOM Biogeochemical Profiling Floats</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sarmiento, J. L.; Bushinksy, S.; Gray, A. R.</p> <p>2016-12-01</p> <p>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is known to play an important role in the global carbon cycle, yet historically our measurements of this remote region have been sparse and heavily biased towards summer. Here we present new estimates of air-sea fluxes of carbon dioxide and oxygen calculated with measurements from autonomous biogeochemical profiling floats. At high latitudes in and southward of the <span class="hlt">Antarctic</span> Circumpolar Current, we find a significant flux of CO2 from the <span class="hlt">ocean</span> to the atmosphere during 2014-2016, which is particularly enhanced during winter months. These results suggest that previous estimates may be biased towards stronger <span class="hlt">Southern</span> <span class="hlt">Ocean</span> CO2 uptake due to undersampling in winter. We examine various implications of having a source of CO2 that is higher than previous estimates. We also find that CO2:O2 flux ratios north of the Subtropical Front are positive, consistent with the fluxes being driven by changes in solubility, while south of the Polar Front biological processes and upwelling of deep water combine to produce a negative CO2:O2 flux ratio.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006TellB..58...73W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006TellB..58...73W"><span>The role of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> mixing and upwelling in glacial-interglacial atmospheric CO2 change</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Watson, Andrew J.; Naveira Garabato, Alberto C.</p> <p>2006-02-01</p> <p>Decreased ventilation of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in glacial time is implicated in most explanations of lower glacial atmospheric CO2. Today, the deep (>2000 m) <span class="hlt">ocean</span> south of the Polar Front is rapidly ventilated from below, with the interaction of deep currents with topography driving high mixing rates well up into the water column. We show from a buoyancy budget that mixing rates are high in all the deep waters of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Between the surface and ~2000 m depth, water is upwelled by a residual meridional overturning that is directly linked to buoyancy fluxes through the <span class="hlt">ocean</span> surface. Combined with the rapid deep mixing, this upwelling serves to return deep water to the surface on a short time scale. We propose two new mechanisms by which, in glacial time, the deep <span class="hlt">Southern</span> <span class="hlt">Ocean</span> may have been more isolated from the surface. Firstly, the deep <span class="hlt">ocean</span> appears to have been more stratified because of denser bottom water resulting from intense sea ice formation near Antarctica. The greater stratification would have slowed the deep mixing. Secondly, subzero atmospheric temperatures may have meant that the present-day buoyancy flux from the atmosphere to the <span class="hlt">ocean</span> surface was reduced or reversed. This in turn would have reduced or eliminated the upwelling (contrary to a common assumption, upwelling is not solely a function of the wind stress but is coupled to the air-sea buoyancy flux too). The observed very close link between <span class="hlt">Antarctic</span> temperatures and atmospheric CO2 could then be explained as a natural consequence of the connection between the air-sea buoyancy flux and upwelling in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, if slower ventilation of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> led to lower atmospheric CO2. Here we use a box model, similar to those of previous authors, to show that weaker mixing and reduced upwelling in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> can explain the low glacial atmospheric CO2 in such a formulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.1690J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.1690J"><span><span class="hlt">Antarctic</span> Climate Variability: Covariance of Ozone and Sea Ice in Atmosphere - <span class="hlt">Ocean</span> Coupled Model Simulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jrrar, Amna; Abraham, N. Luke; Pyle, John A.; Holland, David</p> <p>2014-05-01</p> <p>Changes in sea ice significantly modulate climate change because of its high reflective and insulating nature. While Arctic Sea Ice Extent (SIE) shows a negative trend. <span class="hlt">Antarctic</span> SIE shows a weak but positive trend, estimated at 0.127 x 106 km2 per decade. The trend results from large regional cancellations, more ice in the Weddell and the Ross seas, and less ice in the Amundsen - Bellingshausen seas. A number of studies had demonstrated that stratospheric ozone depletion has had a major impact on the atmospheric circulation, causing a positive trend in the <span class="hlt">Southern</span> Annular Mode (SAM), which has been linked to the observed positive trend in autumn sea ice in the Ross Sea. However, other modelling studies show that models forced with prescribed ozone hole simulate decreased sea ice in all regions comparative to a control run. A recent study has also shown that stratospheric ozone recovery will mitigate <span class="hlt">Antarctic</span> sea ice loss. To verify this assumed relationship, it is important first to investigate the covariance between ozone's natural (dynamical) variability and <span class="hlt">Antarctic</span> sea ice distribution in pre-industrial climate, to estimate the trend due to natural variability. We investigate the relationship between anomalous <span class="hlt">Antarctic</span> ozone years and the subsequent changes in <span class="hlt">Antarctic</span> sea ice distribution in a multidecadal control simulation using the AO-UMUKCA model. The model has a horizontal resolution of 3.75 X 2.5 degrees in longitude and latitude; and 60 hybrid height levels in the vertical, from the surface up to a height of 84 km. The <span class="hlt">ocean</span> component is the NEMO <span class="hlt">ocean</span> model on the ORCA2 tripolar grid, and the sea ice model is CICE. We evaluate the model's performance in terms of sea ice distribution, and we calculate sea ice extent trends for composites of anomalously low versus anomalously high SH polar ozone column. We apply EOF analysis to the seasonal anomalies of sea ice concentration, MSLP, and Z 500, and identify the leading climate modes controlling the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017E%26PSL.476..100W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017E%26PSL.476..100W"><span>Rapid drawdown of Antarctica's Wordie Ice Shelf glaciers in response to ENSO/<span class="hlt">Southern</span> Annular Mode-driven warming in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Walker, C. C.; Gardner, A. S.</p> <p>2017-10-01</p> <p>Here we investigate the largest acceleration in ice flow across all of Antarctica between ∼2008 InSAR and 2014 Landsat velocity mappings. This occurred in glaciers that used to feed into the Wordie Ice Shelf on the west <span class="hlt">Antarctic</span> Peninsula, which rapidly disintegrated in ∼1989. Between 2008 and 2014, these glaciers experienced at least a threefold increase in surface elevation drawdown relative to the 2002-2008 time period. After ∼20 yrs of relative stability, it is unlikely that the ice shelf collapse played a role in the large response. Instead, we find that the rapid acceleration and surface drawdown is linked to enhanced melting at the ice-<span class="hlt">ocean</span> boundary, attributable to changes in winds driven by global atmospheric circulation patterns, namely the El Niño-<span class="hlt">Southern</span> Oscillation (ENSO) and <span class="hlt">Southern</span> Annular Mode (SAM), linking changes in grounded ice to atmospheric-driven <span class="hlt">ocean</span> warming.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5357866','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5357866"><span>Major advance of South Georgia glaciers during the <span class="hlt">Antarctic</span> Cold Reversal following extensive sub-<span class="hlt">Antarctic</span> glaciation</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Graham, Alastair G. C.; Kuhn, Gerhard; Meisel, Ove; Hillenbrand, Claus-Dieter; Hodgson, Dominic A.; Ehrmann, Werner; Wacker, Lukas; Wintersteller, Paul; dos Santos Ferreira, Christian; Römer, Miriam; White, Duanne; Bohrmann, Gerhard</p> <p>2017-01-01</p> <p>The history of glaciations on <span class="hlt">Southern</span> Hemisphere sub-polar islands is unclear. Debate surrounds the extent and timing of the last glacial advance and termination on sub-<span class="hlt">Antarctic</span> South Georgia in particular. Here, using sea-floor geophysical data and marine sediment cores, we resolve the record of glaciation offshore of South Georgia through the transition from the Last Glacial Maximum to Holocene. We show a sea-bed landform imprint of a shelf-wide last glacial advance and progressive deglaciation. Renewed glacier resurgence in the fjords between c. 15,170 and 13,340 yr ago coincided with a period of cooler, wetter climate known as the <span class="hlt">Antarctic</span> Cold Reversal, revealing a cryospheric response to an <span class="hlt">Antarctic</span> climate pattern extending into the Atlantic sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. We conclude that the last glaciation of South Georgia was extensive, and the sensitivity of its glaciers to climate variability during the last termination more significant than implied by previous studies. PMID:28303885</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24299658','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24299658"><span><span class="hlt">Ocean</span> acidification and fertilization in the <span class="hlt">antarctic</span> sea urchin Sterechinus neumayeri: the importance of polyspermy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sewell, Mary A; Millar, Russell B; Yu, Pauline C; Kapsenberg, Lydia; Hofmann, Gretchen E</p> <p>2014-01-01</p> <p><span class="hlt">Ocean</span> acidification (OA), the reduction of the seawater pH as a result of increasing levels of atmospheric CO2, is an important climate change stressor in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and <span class="hlt">Antarctic</span>. We examined the impact of OA on fertilization success in the <span class="hlt">Antarctic</span> sea urchin Sterechinus neumayeri using pH treatment conditions reflective of the current and near-future "pH seascape" for this species: current (control: pH 8.052, 384.1 μatm of pCO2), a high CO2 treatment approximating the 0.2-0.3 unit decrease in pH predicted for 2100 (high CO2: pH 7.830, 666.0 μatm of pCO2), and an intermediate medium CO2 (pH 7.967, 473.4 μatm of pCO2). Using a fertilization kinetics approach and mixed-effect models, we observed significant variation in the OA response between individual male/female pairs (N = 7) and a significant population-level increase (70-100%) in tb (time for a complete block to polyspermy) at medium and high CO2, a mechanism that potentially explains the higher levels of abnormal development seen in OA conditions. However, two pairs showed higher fertilization success with CO2 treatment and a nonsignificant effect. Future studies should focus on the mechanisms and levels of interindividual variability in OA response, so that we can consider the potential for selection and adaptation of organisms to a future <span class="hlt">ocean</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3250512','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3250512"><span>The Discovery of New Deep-Sea Hydrothermal Vent Communities in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and Implications for Biogeography</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Rogers, Alex D.; Tyler, Paul A.; Connelly, Douglas P.; Copley, Jon T.; James, Rachael; Larter, Robert D.; Linse, Katrin; Mills, Rachel A.; Garabato, Alfredo Naveira; Pancost, Richard D.; Pearce, David A.; Polunin, Nicholas V. C.; German, Christopher R.; Shank, Timothy; Boersch-Supan, Philipp H.; Alker, Belinda J.; Aquilina, Alfred; Bennett, Sarah A.; Clarke, Andrew; Dinley, Robert J. J.; Graham, Alastair G. C.; Green, Darryl R. H.; Hawkes, Jeffrey A.; Hepburn, Laura; Hilario, Ana; Huvenne, Veerle A. I.; Marsh, Leigh; Ramirez-Llodra, Eva; Reid, William D. K.; Roterman, Christopher N.; Sweeting, Christopher J.; Thatje, Sven; Zwirglmaier, Katrin</p> <p>2012-01-01</p> <p>Since the first discovery of deep-sea hydrothermal vents along the Galápagos Rift in 1977, numerous vent sites and endemic faunal assemblages have been found along mid-<span class="hlt">ocean</span> ridges and back-arc basins at low to mid latitudes. These discoveries have suggested the existence of separate biogeographic provinces in the Atlantic and the North West Pacific, the existence of a province including the South West Pacific and Indian <span class="hlt">Ocean</span>, and a separation of the North East Pacific, North East Pacific Rise, and South East Pacific Rise. The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is known to be a region of high deep-sea species diversity and centre of origin for the global deep-sea fauna. It has also been proposed as a gateway connecting hydrothermal vents in different <span class="hlt">oceans</span> but is little explored because of extreme conditions. Since 2009 we have explored two segments of the East Scotia Ridge (ESR) in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> using a remotely operated vehicle. In each segment we located deep-sea hydrothermal vents hosting high-temperature black smokers up to 382.8°C and diffuse venting. The chemosynthetic ecosystems hosted by these vents are dominated by a new yeti crab (Kiwa n. sp.), stalked barnacles, limpets, peltospiroid gastropods, anemones, and a predatory sea star. Taxa abundant in vent ecosystems in other <span class="hlt">oceans</span>, including polychaete worms (Siboglinidae), bathymodiolid mussels, and alvinocaridid shrimps, are absent from the ESR vents. These groups, except the Siboglinidae, possess planktotrophic larvae, rare in <span class="hlt">Antarctic</span> marine invertebrates, suggesting that the environmental conditions of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> may act as a dispersal filter for vent taxa. Evidence from the distinctive fauna, the unique community structure, and multivariate analyses suggest that the <span class="hlt">Antarctic</span> vent ecosystems represent a new vent biogeographic province. However, multivariate analyses of species present at the ESR and at other deep-sea hydrothermal vents globally indicate that vent biogeography is more complex than</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29284198','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29284198"><span>Signals from the south; humpback whales carry messages of <span class="hlt">Antarctic</span> sea-ice ecosystem variability.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bengtson Nash, Susan M; Castrillon, Juliana; Eisenmann, Pascale; Fry, Brian; Shuker, Jon D; Cropp, Roger A; Dawson, Amanda; Bignert, Anders; Bohlin-Nizzetto, Pernilla; Waugh, Courtney A; Polkinghorne, Bradley J; Dalle Luche, Greta; McLagan, David</p> <p>2018-04-01</p> <p><span class="hlt">Southern</span> hemisphere humpback whales (Megaptera novaeangliae) rely on summer prey abundance of <span class="hlt">Antarctic</span> krill (Euphausia superba) to fuel one of the longest-known mammalian migrations on the planet. It is hypothesized that this species, already adapted to endure metabolic extremes, will be one of the first <span class="hlt">Antarctic</span> consumers to show measurable physiological change in response to fluctuating prey availability in a changing climate; and as such, a powerful sentinel candidate for the <span class="hlt">Antarctic</span> sea-ice ecosystem. Here, we targeted the sentinel parameters of humpback whale adiposity and diet, using novel, as well as established, chemical and biochemical markers, and assembled a time trend spanning 8 years. We show the synchronous, inter-annual oscillation of two measures of humpback whale adiposity with <span class="hlt">Southern</span> <span class="hlt">Ocean</span> environmental variables and climate indices. Furthermore, bulk stable isotope signatures provide clear indication of dietary compensation strategies, or a lower trophic level isotopic change, following years indicated as leaner years for the whales. The observed synchronicity of humpback whale adiposity and dietary markers, with climate patterns in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, lends strength to the role of humpback whales as powerful <span class="hlt">Antarctic</span> sea-ice ecosystem sentinels. The work carries significant potential to reform current ecosystem surveillance in the <span class="hlt">Antarctic</span> region. © 2017 John Wiley & Sons Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4032513','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4032513"><span>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in the Coupled Model Intercomparison Project phase 5</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Meijers, A. J. S.</p> <p>2014-01-01</p> <p>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is an important part of the global climate system, but its complex coupled nature makes both its present state and its response to projected future climate forcing difficult to model. Clear trends in wind, sea-ice extent and <span class="hlt">ocean</span> properties emerged from multi-model intercomparison in the Coupled Model Intercomparison Project phase 3 (CMIP3). Here, we review recent analyses of the historical and projected wind, sea ice, circulation and bulk properties of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in the updated Coupled Model Intercomparison Project phase 5 (CMIP5) ensemble. Improvements to the models include higher resolutions, more complex and better-tuned parametrizations of <span class="hlt">ocean</span> mixing, and improved biogeochemical cycles and atmospheric chemistry. CMIP5 largely reproduces the findings of CMIP3, but with smaller inter-model spreads and biases. By the end of the twenty-first century, mid-latitude wind stresses increase and shift polewards. All water masses warm, and intermediate waters freshen, while bottom waters increase in salinity. Surface mixed layers shallow, warm and freshen, whereas sea ice decreases. The upper overturning circulation intensifies, whereas bottom water formation is reduced. Significant disagreement exists between models for the response of the <span class="hlt">Antarctic</span> Circumpolar Current strength, for reasons that are as yet unclear. PMID:24891395</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSPC44B2192K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSPC44B2192K"><span>Heat uptake in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in a warmer, windier world: a process-based analysis using an AOGCM with an eddy-permitting <span class="hlt">ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kuhlbrodt, T.; Gregory, J. M.</p> <p>2016-02-01</p> <p>About 90% of the anthropogenic increase in heat stored in the climate system is found the <span class="hlt">oceans</span>. Therefore it is relevant to understand the details of <span class="hlt">ocean</span> heat uptake. Here we present a detailed, process-based analysis of <span class="hlt">ocean</span> heat uptake (OHU) processes in HiGEM1.2, an atmosphere-<span class="hlt">ocean</span> general circulation model (AOGCM) with an eddy-permitting <span class="hlt">ocean</span> component of 1/3° resolution. Similarly to various other models, HiGEM1.2 shows that the global heat budget is dominated by a downward advection of heat compensated by upward isopycnal diffusion. This upward isopycnal diffusion of heat is located mostly in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (Fig. 1a).We compare the responses to a 4xCO2 forcing and an enhancement of the windstress forcing in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. In line with the CMIP5 models, HiGEM1.2 shows a band of strong OHU in the mid-latitude <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in the 4xCO2 run, which is mostly advective. By contrast, in the high-latitude <span class="hlt">Southern</span> <span class="hlt">Ocean</span> regions it is the suppression of convection that leads to OHU (Fig. 1b). In the enhanced windstress run, convection is strengthened at high <span class="hlt">Southern</span> latitudes (Fig. 1c), leading to heat loss, while the magnitude of the OHU in the <span class="hlt">Southern</span> mid-latitudes is very similar to the 4xCO2 results. Remarkably, there is only very small global OHU in the enhanced windstress run. The wind stress forcing just leads to a redistribution of heat. We relate the <span class="hlt">ocean</span> changes at high <span class="hlt">southern</span> latitudes to the effect of climate change on the <span class="hlt">Antarctic</span> Circumpolar Current (ACC). It weakens in the 4xCO2 run and strengthens in the wind stress run. The weakening is due to a narrowing of the ACC, caused by an expansion of the Weddell Gyre, and a flattening of the isopycnals, which are explained by a combination of the wind stress forcing and increased precipitation. The presentation will also try to clarify the definitions of terms like "advective", "diffusive" and "eddy-induced" when used for observed and modelled (at various resolutions) <span class="hlt">ocean</span> heat</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRC..123.2238P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRC..123.2238P"><span>Seasonal Variation of Barrier Layer in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pan, Li; Zhong, Yisen; Liu, Hailong; Zhou, Lei; Zhang, Zhaoru; Zhou, Meng</p> <p>2018-03-01</p> <p>The seasonal variability of barrier layer (BL) and its formation mechanism in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> are investigated using the most recent Argo data. The results reveal that the BL is a persistent feature in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> with a strong seasonal cycle. The thickest BL appears in winter with the maximum amplitude exceeding 250 m while it dramatically decreases to less than 50 m in summer. The spatial distribution of BL is zonally oriented in the Pacific and Indian <span class="hlt">Ocean</span> sectors, which is in agreement with that of the mixed layer depth (MLD) and the isothermal layer depth (ILD). Two areas with the most prominent BL are identified. One is located south of Australia and the other in the southeastern Pacific. The BL formation in both areas is generally attributed to a shallow mixed layer controlled by surface freshwater intrusion and a deep isothermal layer modulated by seasonal vertical convection. In the former region, the cold and fresh <span class="hlt">Antarctic</span> Surface Water (ASW) is transported northward across the Subantarctic Front (SAF) by the Ekman effect and overlies the warm Subantarctic Mode Water (SAMW). The resulting inverse temperature structure facilitates the development of thick BLs. In the latter region, the BL emerges in the ventilation area where the shallow Surface Salinity Minimum Water (SSMW) coming from north leans against the deep vertical isotherms. In summer, positive surface heat flux into the <span class="hlt">ocean</span> overwhelms other thermodynamic effects in the mixed layer heat budget. The MLD and ILD coincide and thus the BL is destroyed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMOS13C1250C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMOS13C1250C"><span>Comparisons of The Habitat Utilization Of Top Predators In The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> And The North Pacific</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Costa, D. P.; Robinson, P.; Huckstadt, L. E.; Crocker, D. E.; Goebel, M. E.</p> <p>2010-12-01</p> <p>Northern and <span class="hlt">Southern</span> elephant seals (Mirounga angustirostris, M. leonina) separated some 4 MYA. While these congeners are physiologically very similar and thus have the potential to forage in similar ways they inhabit very different habitats. While <span class="hlt">southern</span> elephant seals (SES) are distributed throughout the <span class="hlt">southern</span> <span class="hlt">ocean</span>, northern elephant seals (NES) are limited to the Northeast Pacific <span class="hlt">Ocean</span> and range over lower latitudes than SES. In order to compare and contrast the physiological capability and response to different habitats we compared the foraging behavior of 167 adult female northern elephant seals (Año Nuevo and San Benitos Islands) and 55 <span class="hlt">southern</span> elephant seals (Livingston Island, <span class="hlt">Antarctic</span> Peninsula) using satellite telemetry and dive recorders. As expected both species carried out very similar dive depths (NES 509m ± 166 vs SES 345m±79) and dive durations (NES 23.0 min ± 6.7; SES 22.5 min ± 5.0). However, there were significant differences in their foraging pattern that we attribute to differences in the availability of continental shelf and suitable foraging habitat. While 85% of NES females foraged offshore, the dominant strategy for SES was benthic foraging on the continental shelf. Even with the differences in habitat, the fundamental components of their foraging patterns remained the same as when they foraged pelagically they both species relied on persistent large scale oceanographic features where mixing enhances productivity such as the North Pacific Transition zone (NES) and the <span class="hlt">Southern</span> <span class="hlt">Antarctic</span> Circumpolar Current Front (SES). Given the very different habitats and prey species consumed by these two species their overall foraging behavior is surprisingly similar suggesting that as a mesopelagic predator the elephant seal design is rather robust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012SedG..247...21L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012SedG..247...21L"><span>A review of Tertiary climate changes in <span class="hlt">southern</span> South America and the <span class="hlt">Antarctic</span> Peninsula. Part 2: continental conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Le Roux, J. P.</p> <p>2012-03-01</p> <p>Climate changes in <span class="hlt">southern</span> South America and the <span class="hlt">Antarctic</span> Peninsula during the Tertiary show a strong correlation with <span class="hlt">ocean</span> warming and cooling events, which are in turn related to tectonic processes. During periods of accelerated sea-floor spreading and mid-<span class="hlt">ocean</span> ridge activity, sea-levels rose so that parts of the continents were flooded and forests were destroyed. However, this was balanced by the large-scale release of CO2 during volcanic outgassing and carbonate precipitation on the continental shelves, which caused rising air temperatures and the poleward expansion of (sub)tropical and temperate forests. Cooling episodes generally caused an increase in the north-south thermal gradient because of an equatorward shift in climate belts, so that the Westerly Winds intensified and brought higher rainfall to the lower latitudes. An increase in wind-blown dust caused temperatures to drop further by reflecting sunlight back into space. The rising Andes Range had a marked influence on climate patterns. Up to the middle Miocene it was still low enough to allow summer rainfall to reach central and north-central Chile, but after about 14 Ma it rose rapidly and effectively blocked the spill-over of moisture from the Atlantic <span class="hlt">Ocean</span> and Amazon Basin. At this time, the cold Humboldt Current was also established, which together with the Andes helped to create the "Arid Diagonal" of <span class="hlt">southern</span> South America stretching from the Atacama Desert to the dry steppes of Patagonia. This caused the withdrawal of subtropical forests to south-central Chile and the expansion of sclerophytic vegetation to central Chile. However, at the same time it intercepted more rain from the northeast, causing the effect of the South American monsoon to intensify in northwestern Argentina and <span class="hlt">southern</span> Bolivia, where forest communities presently occur. In Patagonia, glaciation started as early as 10.5 Ma, but by 7 Ma had become a prominent feature of the landscape and continued apparently</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ClDy..tmp...48B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ClDy..tmp...48B"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> carbon-wind stress feedback</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bronselaer, Ben; Zanna, Laure; Munday, David R.; Lowe, Jason</p> <p>2018-02-01</p> <p>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is the largest sink of anthropogenic carbon in the present-day climate. Here, <span class="hlt">Southern</span> <span class="hlt">Ocean</span> pCO2 and its dependence on wind forcing are investigated using an equilibrium mixed layer carbon budget. This budget is used to derive an expression for <span class="hlt">Southern</span> <span class="hlt">Ocean</span> pCO2 sensitivity to wind stress. <span class="hlt">Southern</span> <span class="hlt">Ocean</span> pCO2 is found to vary as the square root of area-mean wind stress, arising from the dominance of vertical mixing over other processes such as lateral Ekman transport. The expression for pCO2 is validated using idealised coarse-resolution <span class="hlt">ocean</span> numerical experiments. Additionally, we show that increased (decreased) stratification through surface warming reduces (increases) the sensitivity of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> pCO2 to wind stress. The scaling is then used to estimate the wind-stress induced changes of atmospheric pCO_2 in CMIP5 models using only a handful of parameters. The scaling is further used to model the anthropogenic carbon sink, showing a long-term reversal of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> sink for large wind stress strength.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.C31A0633O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.C31A0633O"><span>Quantitative Assessment of <span class="hlt">Antarctic</span> Climate Variability and Change</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ordonez, A.; Schneider, D. P.</p> <p>2013-12-01</p> <p>The <span class="hlt">Antarctic</span> climate is both extreme and highly variable, but there are indications it may be changing. As the climate in Antarctica can affect global sea level and <span class="hlt">ocean</span> circulation, it is important to understand and monitor its behavior. Observational and model data have been used to study climate change in Antarctica and the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, though observational data is sparse and models have difficulty reproducing many observed climate features. For example, a leading hypothesis that ozone depletion has been responsible for sea ice trends is struggling with the inability of ozone-forced models to reproduce the observed sea ice increase. The extent to which this data-model disagreement represents inadequate observations versus model biases is unknown. This research assessed a variety of climate change indicators to present an overview of <span class="hlt">Antarctic</span> climate that will allow scientists to easily access this data and compare indicators with other observational data and model output. Indicators were obtained from observational and reanalysis data for variables such as temperature, sea ice area, and zonal wind stress. Multiple datasets were used for key variables. Monthly and annual anomaly data from Antarctica and the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> as well as tropical indices were plotted as time series on common axes for comparison. Trends and correlations were also computed. Zonal wind, surface temperature, and austral springtime sea ice had strong relationships and were further discussed in terms of how they may relate to climate variability and change in the <span class="hlt">Antarctic</span>. This analysis will enable hypothesized mechanisms of <span class="hlt">Antarctic</span> climate change to be critically evaluated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhyA..499..233O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhyA..499..233O"><span>Time series analysis of the <span class="hlt">Antarctic</span> Circumpolar Wave via symbolic transfer entropy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Oh, Mingi; Kim, Sehyun; Lim, Kyuseong; Kim, Soo Yong</p> <p>2018-06-01</p> <p>An attempt to interpret a large-scale climate phenomenon in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (SO), the <span class="hlt">Antarctic</span> Circumpolar Wave (ACW), has been made using an information entropy method, symbolic transfer entropy (STE). Over the areas of 50-60∘S latitude belt, information flow for four climate variables, sea surface temperature (SST), sea-ice edge (SIE), sea level pressure (SLP) and meridional wind speed (MWS) is examined. We found a tendency that eastward flow of information is preferred only for <span class="hlt">oceanic</span> variables, which is a main characteristic of the ACW, an eastward wave making a circuit around the Antarctica. Since the ACW is the coherent pattern in both <span class="hlt">ocean</span> and atmosphere it is reasonable to infer that the tendency reflects the <span class="hlt">Antarctic</span> Circumpolar Current (ACC) encircling the Antarctica, rather than an evidence of the ACW. We observed one common feature for all four variables, a strong information flow over the area of the eastern Pacific <span class="hlt">Ocean</span>, which suggest a signature of El Nino <span class="hlt">Southern</span> Oscillation (ENSO).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70011113','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70011113"><span>Development of the Circum-<span class="hlt">Antarctic</span> Current</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Kennett, J.P.; Houtz, R.E.; Andrews, P.B.; Edwards, A.R.; Gostin, V.A.; Hajos, M.; Hampton, M.A.; Jenkins, D.G.; Margolis, S.V.; Ovenshine, A.T.; Perch-Nielsen, K.</p> <p>1974-01-01</p> <p>Deep-sea drilling in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> south of Australia and New Zealand shows that the Circum-<span class="hlt">Antarctic</span> Current developed about 30 million years ago in the middle to late Oligocene when final separation occurred between Antarctica and the continental Soulth Tasman Rise. Australia had commenced drifting northward from Antarctica 20 million years before this.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/841814','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/841814"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> Iron Experiment (SOFex)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Coale, Kenneth H.</p> <p></p> <p>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Iron Experiment (SOFeX) was an experiment decades in the planning. It's implementation was among the most complex ship operations that SIO has been involved in. The SOFeX field expedition was successful in creating and tracking two experimentally enriched areas of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, one characterized by low silicic acid, one characterized by high silicic acid. Both experimental sites were replete with abundant nitrate. About 100 scientists were involved overall. The major findings of this study were significant in several ways: (1) The productivity of the <span class="hlt">southern</span> <span class="hlt">ocean</span> is limited by iron availability. (2) Carbon uptake and fluxmore » is therefore controlled by iron availability (3) In spite of low silicic acid, iron promotes non-silicious phytoplankton growth and the uptake of carbon dioxide. (4) The transport of fixed carbon from the surface layers proceeds with a C:N ratio that would indicate differential remineralization of nitrogen at shallow depths. (5) These finding have major implications for modeling of carbon export based on nitrate utilization. (6) The general results of the experiment indicate that, beyond other <span class="hlt">southern</span> <span class="hlt">ocean</span> enrichment experiments, iron inputs have a much wider impact of productivity and carbon cycling than previously demonstrated. Scientific presentations: Coale, K., Johnson, K, Buesseler, K., 2002. The SOFeX Group. Eos. Trans. AGU 83(47) OS11A-0199. Coale, K., Johnson, K. Buesseler, K., 2002. SOFeX: <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Iron Experiments. Overview and Experimental Design. Eos. Trans. AGU 83 (47) OS22D-01. Buesseler, K.,et al. 2002. Does Iron Fertilization Enhance Carbon Sequestration? Particle flux results from the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Iron Experiment. Eos. Trans. AGU 83 (47), OS22D-09. Johnson, K. et al. 2002. Open <span class="hlt">Ocean</span> Iron Fertilization Experiments From IronEx-I through SOFeX: What We Know and What We Still Need to Understand. Eos. Trans. AGU 83 (47), OS22D-12. Coale, K. H., 2003. Carbon and Nutrient Cycling During the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013DSRII..88...47M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013DSRII..88...47M"><span>Foraging habitats of <span class="hlt">southern</span> elephant seals, Mirounga leonina, from the Northern <span class="hlt">Antarctic</span> Peninsula</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Muelbert, Monica M. C.; de Souza, Ronald B.; Lewis, Mirtha N.; Hindell, Mark A.</p> <p>2013-04-01</p> <p>Elephant Island (EI) is uniquely placed to provide <span class="hlt">southern</span> elephant seals (SES) breeding there with potential access to foraging grounds in the Weddell Sea, the frontal zones of the South Atlantic <span class="hlt">Ocean</span>, the Patagonian shelf and the Western <span class="hlt">Antarctic</span> Peninsula (WAP). Quantifying where seals from EI forage therefore provides insights into the types of important habitats available, and which are of particular importance to elephant seals. Twenty nine SES (5 sub-adult males—SAM and 24 adult females—AF) were equipped with SMRU CTD-SLDRs during the post-breeding (PB 2008, 2009) and post-moulting (PM 2007, 2008, 2009, 2010) trips to sea. There were striking intra-annual and inter-sex differences in foraging areas, with most of the PB females remaining within 150 km of EI. One PB AF travelled down the WAP as did 16 out of the 20 PM females and foraged near the winter ice-edge. Most PM sub-adult males remained close to EI, in areas similar to those used by adult females several months earlier, although one SAM spent the early part of the winter foraging on the Patagonian Shelf. The waters of the Northern <span class="hlt">Antarctic</span> Peninsula (NAP) contain abundant resources to support the majority of the Islands' SES for the summer and early winter, such that the animals from this population have shorter migrations than those from most other populations. Sub-adult males and PB females are certainly taking advantage of these resources. However, PM females did not remain there over the winter months, instead they used the same waters at the ice-edge in the <span class="hlt">southern</span> WAP that females from both King George Island and South Georgia used. Females made more benthic dives than sub-adult males—again this contrasts with other sites where SAMs do more benthic diving. Unlike most other populations studied to date EI is a relatively southerly breeding colony located on the <span class="hlt">Antarctic</span> continental shelf. EI seals are using shelf habitats more than other SES populations but some individuals still</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3870680','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3870680"><span>Thick-shelled, grazer-protected diatoms decouple <span class="hlt">ocean</span> carbon and silicon cycles in the iron-limited <span class="hlt">Antarctic</span> Circumpolar Current</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Assmy, Philipp; Smetacek, Victor; Montresor, Marina; Klaas, Christine; Henjes, Joachim; Strass, Volker H.; Arrieta, Jesús M.; Bathmann, Ulrich; Berg, Gry M.; Breitbarth, Eike; Cisewski, Boris; Friedrichs, Lars; Fuchs, Nike; Herndl, Gerhard J.; Jansen, Sandra; Krägefsky, Sören; Latasa, Mikel; Peeken, Ilka; Röttgers, Rüdiger; Scharek, Renate; Schüller, Susanne E.; Steigenberger, Sebastian; Webb, Adrian; Wolf-Gladrow, Dieter</p> <p>2013-01-01</p> <p>Diatoms of the iron-replete continental margins and North Atlantic are key exporters of organic carbon. In contrast, diatoms of the iron-limited <span class="hlt">Antarctic</span> Circumpolar Current sequester silicon, but comparatively little carbon, in the underlying deep <span class="hlt">ocean</span> and sediments. Because the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is the major hub of <span class="hlt">oceanic</span> nutrient distribution, selective silicon sequestration there limits diatom blooms elsewhere and consequently the biotic carbon sequestration potential of the entire <span class="hlt">ocean</span>. We investigated this paradox in an in situ iron fertilization experiment by comparing accumulation and sinking of diatom populations inside and outside the iron-fertilized patch over 5 wk. A bloom comprising various thin- and thick-shelled diatom species developed inside the patch despite the presence of large grazer populations. After the third week, most of the thinner-shelled diatom species underwent mass mortality, formed large, mucous aggregates, and sank out en masse (carbon sinkers). In contrast, thicker-shelled species, in particular Fragilariopsis kerguelensis, persisted in the surface layers, sank mainly empty shells continuously, and reduced silicate concentrations to similar levels both inside and outside the patch (silica sinkers). These patterns imply that thick-shelled, hence grazer-protected, diatom species evolved in response to heavy copepod grazing pressure in the presence of an abundant silicate supply. The ecology of these silica-sinking species decouples silicon and carbon cycles in the iron-limited <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, whereas carbon-sinking species, when stimulated by iron fertilization, export more carbon per silicon. Our results suggest that large-scale iron fertilization of the silicate-rich <span class="hlt">Southern</span> <span class="hlt">Ocean</span> will not change silicon sequestration but will add carbon to the sinking silica flux. PMID:24248337</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=238500','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=238500"><span>Spatial Distribution, Structure, Biomass, and Physiology of Microbial Assemblages across the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Frontal Zones during the Late Austral Winter</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hanson, Roger B.; Lowery, H. Kenneth</p> <p>1985-01-01</p> <p>We examined the spatial distributions of picoplankton, nanoplankton, and microplankton biomass and physiological state relative to the hydrography of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> along 90° W longitude and across the Drake Passage in the late austral winter. The eastern South Pacific <span class="hlt">Ocean</span> showed some large-scale biogeographical differences and size class variability. Microbial ATP biomass was greatest in euphotic surface waters. The horizontal distributions of microbial biomass and physiological state (adenylate energy charge ratio) coincided with internal currents (fronts) of the <span class="hlt">Antarctic</span> Circumpolar Current. In the Drake Passage, the biological scales in the euphotic and aphotic zones were complex, and ATP, total adenylate, and adenylate energy charge ratio isopleths were compressed due to the extension of the sea ice from Antarctica and constriction of the Circumpolar Current through the narrow passage. The physiological state of microbial assemblages and biomass were much higher in the Drake Passage than in the eastern South Pacific <span class="hlt">Ocean</span>. The temperature of <span class="hlt">Antarctic</span> waters, not dissolved organic carbon, was the major variable controlling picoplankton growth. Estimates of picoplankton production based on ATP increments with time suggest that production under reduced predation pressure was 1 to 10 μg of carbon per liter per day. Our results demonstrate the influence of large-scale hydrographic processes on the distribution and structure of microplankton, nanoplankton, and picoplankton across the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. PMID:16346777</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMPP43B1348B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMPP43B1348B"><span>Variations of the <span class="hlt">Antarctic</span> Circumpolar Current (ACC) in the Kerguelen Sector during the Last Deglaciation : sedimentological and geochemical evidences</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bout-Roumazeilles, V.; Beny, F.; Mazaud, A.; Michel, E.; Crosta, X.; Davies, G. R.; Bory, A. J. M.</p> <p>2017-12-01</p> <p>High-resolution sedimentological and geochemical records were obtained from two sediment cores recovered by the French R/V Marion Dufresne during the INDIEN-SUD-ACC cruises near the sub-<span class="hlt">Antarctic</span> Kerguelen Islands (49°S). This area is ideal to record past <span class="hlt">oceanic</span> and atmospheric changes in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> because they are currently located in the northern branch of the <span class="hlt">Antarctic</span> Circumpolar Current and under the direct influence of <span class="hlt">Southern</span> Hemisphere Westerly wind belt. This study focuses on the last termination, with specific emphasis on the impact of severe climatic events (Heinrich Stadial 1, <span class="hlt">Antarctic</span> Cold Reversal, Younger Dryas) onto the <span class="hlt">ocean</span>-atmospheric exchange. Results indicates that most of the sediment is derived from the Kerguelen Plateau, characterized by high smectite content. Periodically, a minor contribution of Antarctica is noticeable. In particular, illite variations suggest fast and short northward incursions of <span class="hlt">Antarctic</span> Bottom Water, probably formed in the Prydz Bay during the last glaciation. Grainsize repartition combined to magnetic parameters show a southward migration of the ACC and the fronts associated from the beginning of the deglaciation, which is consistent with <span class="hlt">Southern</span> Hemisphere climate variations. On the opposite, it highlights an asynchronous decrease of the ACC strength, with a large drop during the <span class="hlt">Antarctic</span> Cold Reversal when atmospheric CO2 increase was slowed down. Thus, at least in the studied area, the ACC strength and the <span class="hlt">Antarctic</span> Climate were not synchronous during the last deglaciation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018BGeo...15.1843R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018BGeo...15.1843R"><span>Coccolithophore populations and their contribution to carbonate export during an annual cycle in the Australian sector of the <span class="hlt">Antarctic</span> zone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rigual Hernández, Andrés S.; Flores, José A.; Sierro, Francisco J.; Fuertes, Miguel A.; Cros, Lluïsa; Trull, Thomas W.</p> <p>2018-03-01</p> <p>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is experiencing rapid and relentless change in its physical and biogeochemical properties. The rate of warming of the <span class="hlt">Antarctic</span> Circumpolar Current exceeds that of the global <span class="hlt">ocean</span>, and the enhanced uptake of carbon dioxide is causing basin-wide <span class="hlt">ocean</span> acidification. Observational data suggest that these changes are influencing the distribution and composition of pelagic plankton communities. Long-term and annual field observations on key environmental variables and organisms are a critical basis for predicting changes in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ecosystems. These observations are particularly needed, since high-latitude systems have been projected to experience the most severe impacts of <span class="hlt">ocean</span> acidification and invasions of allochthonous species. Coccolithophores are the most prolific calcium-carbonate-producing phytoplankton group playing an important role in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> biogeochemical cycles. Satellite imagery has revealed elevated particulate inorganic carbon concentrations near the major circumpolar fronts of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> that can be attributed to the coccolithophore Emiliania huxleyi. Recent studies have suggested changes during the last decades in the distribution and abundance of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> coccolithophores. However, due to limited field observations, the distribution, diversity and state of coccolithophore populations in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> remain poorly characterised. We report here on seasonal variations in the abundance and composition of coccolithophore assemblages collected by two moored sediment traps deployed at the <span class="hlt">Antarctic</span> zone south of Australia (2000 and 3700 m of depth) for 1 year in 2001-2002. Additionally, seasonal changes in coccolith weights of E. huxleyi populations were estimated using circularly polarised micrographs analysed with C-Calcita software. Our findings indicate that (1) coccolithophore sinking assemblages were nearly monospecific for E. huxleyi morphotype B/C in the <span class="hlt">Antarctic</span> zone waters in 2001-2002; (2</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4023264','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4023264"><span><span class="hlt">Antarctic</span> Porifera database from the Spanish benthic expeditions</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Rios, Pilar; Cristobo, Javier</p> <p>2014-01-01</p> <p>Abstract The information about the sponges in this dataset is derived from the samples collected during five Spanish <span class="hlt">Antarctic</span> expeditions: Bentart 94, Bentart 95, Gebrap 96, Ciemar 99/00 and Bentart 2003. Samples were collected in the <span class="hlt">Antarctic</span> Peninsula and Bellingshausen Sea at depths ranging from 4 to 2044 m using various sampling gears. The <span class="hlt">Antarctic</span> Porifera database from the Spanish benthic expeditions is unique as it provides information for an under-explored region of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (Bellingshausen Sea). It fills an information gap on <span class="hlt">Antarctic</span> deep-sea sponges, for which there were previously very few data. This phylum is an important part of the <span class="hlt">Antarctic</span> biota and plays a key role in the structure of the <span class="hlt">Antarctic</span> marine benthic community due to its considerable diversity and predominance in different areas. It is often a dominant component of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> benthic communities. The quality of the data was controlled very thoroughly with GPS systems onboard the R/V Hesperides and by checking the data against the World Porifera Database (which is part of the World Register of Marine Species, WoRMS). The data are therefore fit for completing checklists, inclusion in biodiversity pattern analysis and niche modelling. The authors can be contacted if any additional information is needed before carrying out detailed biodiversity or biogeographic studies. The dataset currently contains 767 occurrence data items that have been checked for systematic reliability. This database is not yet complete and the collection is growing. Specimens are stored in the author’s collection at the Spanish Institute of Oceanography (IEO) in the city of Gijón (Spain). The data are available in GBIF. PMID:24843257</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002JCli...15..487K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002JCli...15..487K"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> Climate and Sea Ice Anomalies Associated with the <span class="hlt">Southern</span> Oscillation.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kwok, R.; Comiso, J. C.</p> <p>2002-03-01</p> <p>The anomalies in the climate and sea ice cover of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and their relationships with the <span class="hlt">Southern</span> Oscillation (SO) are investigated using a 17-yr dataset from 1982 to 1998. The polar climate anomalies are correlated with the <span class="hlt">Southern</span> Oscillation index (SOI) and the composites of these anomalies are examined under the positive (SOI > 0), neutral (0 > SOI > 1), and negative (SOI < 1) phases of SOI. The climate dataset consists of sea level pressure, wind, surface air temperature, and sea surface temperature fields, while the sea ice dataset describes its extent, concentration, motion, and surface temperature. The analysis depicts, for the first time, the spatial variability in the relationship of the above variables with the SOI. The strongest correlation between the SOI and the polar climate anomalies are found in the Bellingshausen, Amundsen, and Ross Seas. The composite fields reveal anomalies that are organized in distinct large-scale spatial patterns with opposing polarities at the two extremes of SOI, and suggest oscillations that are closely linked to the SO. Within these sectors, positive (negative) phases of the SOI are generally associated with lower (higher) sea level pressure, cooler (warmer) surface air temperature, and cooler (warmer) sea surface temperature in these sectors. Associations between these climate anomalies and the behavior of the <span class="hlt">Antarctic</span> sea ice cover are evident. Recent anomalies in the sea ice cover that are clearly associated with the SOI include the following: the record decrease in the sea ice extent in the Bellingshausen Sea from mid-1988 to early 1991; the relationship between Ross Sea SST and the ENSO signal, and reduced sea ice concentration in the Ross Sea; and the shortening of the ice season in the eastern Ross Sea, Amundsen Sea, far western Weddell Sea and lengthening of the ice season in the western Ross Sea, Bellinghausen Sea, and central Weddell Sea gyre during the period 1988-94. Four ENSO episodes over the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PolSc..12...69O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PolSc..12...69O"><span>Spatial distribution of Salpa thompsoni in the high <span class="hlt">Antarctic</span> area off Adélie Land, East Antarctica during the austral summer 2008</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ono, Atsushi; Moteki, Masato</p> <p>2017-06-01</p> <p>The salp Salpa thompsoni has the potential to alter the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ecosystem through competition with krill Euphausia superba. Information on the reproductive status of S. thompsoni in the high <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is thus essential to understanding salp population growth and predicting changes in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ecosystem. We carried out stratified and quantitative sampling from the surface to a depth of 2000 m during the austral summer of 2008 to determine the spatial distribution and population structure of S. thompsoni in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> off Adélie Land. We found two salp species, S. thompsoni and Ihlea racovitzai, with the former being dominant. S. thompsoni was distributed north of the continental slope area, while I. racovitzai was observed in the neritic zone. Mature aggregates and solitary specimens of S. thompsoni were found south of the <span class="hlt">Southern</span> Boundary of the <span class="hlt">Antarctic</span> Circumpolar Current, suggesting that S. thompsoni is able to complete its life cycle in high <span class="hlt">Antarctic</span> waters during the austral summer. However, S. thompsoni was sparsely distributed in the continental slope area, and absent south of the <span class="hlt">Antarctic</span> Slope Front, suggesting that it is less competitive with krill for food in the slope area off Adélie Land, where krill is densely distributed during the austral summer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25999505','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25999505"><span>Glacier mass loss. Dynamic thinning of glaciers on the <span class="hlt">Southern</span> <span class="hlt">Antarctic</span> Peninsula.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wouters, B; Martin-Español, A; Helm, V; Flament, T; van Wessem, J M; Ligtenberg, S R M; van den Broeke, M R; Bamber, J L</p> <p>2015-05-22</p> <p>Growing evidence has demonstrated the importance of ice shelf buttressing on the inland grounded ice, especially if it is resting on bedrock below sea level. Much of the <span class="hlt">Southern</span> <span class="hlt">Antarctic</span> Peninsula satisfies this condition and also possesses a bed slope that deepens inland. Such ice sheet geometry is potentially unstable. We use satellite altimetry and gravity observations to show that a major portion of the region has, since 2009, destabilized. Ice mass loss of the marine-terminating glaciers has rapidly accelerated from close to balance in the 2000s to a sustained rate of -56 ± 8 gigatons per year, constituting a major fraction of Antarctica's contribution to rising sea level. The widespread, simultaneous nature of the acceleration, in the absence of a persistent atmospheric forcing, points to an <span class="hlt">oceanic</span> driving mechanism. Copyright © 2015, American Association for the Advancement of Science.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ClDy...50.1451Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ClDy...50.1451Z"><span>Seasonal <span class="hlt">southern</span> hemisphere multi-variable reflection of the <span class="hlt">southern</span> annular mode in atmosphere and <span class="hlt">ocean</span> reanalyses</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Zhaoru; Uotila, Petteri; Stössel, Achim; Vihma, Timo; Liu, Hailong; Zhong, Yisen</p> <p>2018-02-01</p> <p>Variations of <span class="hlt">southern</span> hemisphere (SH) climate variables are often linked to the <span class="hlt">southern</span> annular mode (SAM) variability. We examined such linkage by seasons using state-of-the-art atmosphere and <span class="hlt">ocean</span>/sea-ice reanalyses. The associated SAM related anomaly (SRA) fields of the climate variables, denoting anomalies corresponding to the same variation in SAM, are overall consistent across the reanalyses. Among the atmospheric products, 20CRV2 differs from ERA-interim and CFSR in the sea-level pressure SRAs over the Amundsen Sea, resulting in less warming over the <span class="hlt">Antarctic</span> Peninsula. Among the <span class="hlt">ocean</span> reanalyses, ORAP5 and C-GLORS exhibit the largest consistency. The major difference between them and the lower-resolution CFSR and SODA reanalyses is deeper penetration of anomalous meridional currents. Compared to the other <span class="hlt">ocean</span> reanalyses, CFSR exhibits stronger and spatially more coherent surface-current SRAs, resulting in greater SRAs of sea-ice motion and ice thickness along the ice edges. The SRAs of sensible and total surface heat fluxes are reduced in CFSR due to <span class="hlt">ocean</span>-atmosphere coupling. Significant sea-ice concentration SRAs are present on the west side of peninsulas along the east Antarctica coast in spring and winter, most notably in ORAP5 and C-GLORS, implying changes in new-ice production and shelf-water formation. Most atmosphere and <span class="hlt">ocean</span> variables manifest an annular SRA pattern in summer and a non-annular pattern in the other seasons, with a wavenumber-3 structure strongest in autumn and weakest in summer. The wavenumber-3 structure should be related to the zonal wave three pattern of the SH circulation, the relation of which to SAM needs further exploration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ERL....12h4010L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ERL....12h4010L"><span>Improved simulation of <span class="hlt">Antarctic</span> sea ice due to the radiative effects of falling snow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, J.-L. F.; Richardson, Mark; Hong, Yulan; Lee, Wei-Liang; Wang, Yi-Hui; Yu, Jia-Yuh; Fetzer, Eric; Stephens, Graeme; Liu, Yinghui</p> <p>2017-08-01</p> <p><span class="hlt">Southern</span> <span class="hlt">Ocean</span> sea-ice cover exerts critical control on local albedo and <span class="hlt">Antarctic</span> precipitation, but simulated <span class="hlt">Antarctic</span> sea-ice concentration commonly disagrees with observations. Here we show that the radiative effects of precipitating ice (falling snow) contribute substantially to this discrepancy. Many models exclude these radiative effects, so they underestimate both shortwave albedo and downward longwave radiation. Using two simulations with the climate model CESM1, we show that including falling-snow radiative effects improves the simulations relative to cloud properties from CloudSat-CALIPSO, radiation from CERES-EBAF and sea-ice concentration from passive microwave sensors. From 50-70°S, the simulated sea-ice-area bias is reduced by 2.12 × 106 km2 (55%) in winter and by 1.17 × 106 km2 (39%) in summer, mainly because increased wintertime longwave heating restricts sea-ice growth and so reduces summer albedo. Improved <span class="hlt">Antarctic</span> sea-ice simulations will increase confidence in projected <span class="hlt">Antarctic</span> sea level contributions and changes in global warming driven by long-term changes in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> feedbacks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AIPC.1479..650S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AIPC.1479..650S"><span>Mapping unstable manifolds using drifters/floats in a <span class="hlt">Southern</span> <span class="hlt">Ocean</span> field campaign</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shuckburgh, Emily F.</p> <p>2012-09-01</p> <p>Ideas from dynamical systems theory have been used in an observational field campaign in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> to provide information on the mixing structure of the flow. Instantaneous snapshops of data from satellite altimetry provide information concerning surface currents at a scale of 100 km or so. We show that by using time-series of satellite altimetry we are able to deduce reliable information about the structure of the surface flow at scales as small as 10 km or so. This information was used in near-real time to provide an estimate of the location of stable and unstable manifolds in the vicinity of the <span class="hlt">Antarctic</span> Circumpolar Current. As part of a large U.K./U.S. observational field campaign (DIMES: Diapycnal and Isopycnal Mixing Experiment in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>) a number of drifters and floats were then released (at the surface and at a depth of approximately 1 km) close to the estimated hyperbolic point at the intersection of the two manifolds, in several locations with apparently different dynamical characteristics. The subsequent trajectories of the drifters/floats has allowed the unstable manifolds to be tracked, and the relative separation of pairs of floats has allowed an estimation of Lyapunov exponents. The results of these deployments have given insight into the strengths and limitations of the satellite data which does not resolve small scales in the velocity field, and have elucidated the transport and mixing structure of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> at the surface and at depth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMPP11D..08B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMPP11D..08B"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> Control of Glacial AMOC Stability and Dansgaard-Oeschger Interstadial Duration</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Buizert, C.; Schmittner, A.</p> <p>2016-12-01</p> <p>Glacial periods exhibit abrupt Dansgaard-Oeschger (DO) climatic oscillations that are thought to be linked to instabilities in the Atlantic meridional overturning circulation (AMOC). Great uncertainty remains regarding the dynamics of the DO cycle, as well as controls on the timing and duration of individual events. Using ice core data we show that the duration of warm (interstadial) periods is strongly correlated with <span class="hlt">Antarctic</span> climate, and presumably with <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (SO) temperature and the position of the <span class="hlt">Southern</span> Hemisphere (SH) westerlies. We propose a SO control on AMOC stability and interstadial duration via the rate of <span class="hlt">Antarctic</span> bottom water formation, meridional density/pressure gradients, Agulhas Leakage, and SO adiabatic upwelling. This hypothesis is supported by climate model experiments that demonstrate SO warming leads to a stronger AMOC that is less susceptible to freshwater perturbations. In the AMOC stability diagram, SO warming and strengthening of the SH westerlies both shift the vigorous AMOC branch toward higher freshwater values, thus raising the threshold for AMOC collapse. The proposed mechanism could provide a consistent explanation for several diverse observations, including maximum DO activity during intermediate ice volume/SH temperature, and successively shorter DO durations within each Bond cycle. It may further have implications for the fate of the AMOC under future global warming.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EP%26S...69...93L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EP%26S...69...93L"><span>Variation of <span class="hlt">Antarctic</span> circumpolar current and its intensification in relation to the <span class="hlt">southern</span> annular mode detected in the time-variable gravity signals by GRACE satellite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liau, Jen-Ru; Chao, Benjamin F.</p> <p>2017-07-01</p> <p>The <span class="hlt">southern</span> annular mode (SAM) in the atmosphere and the <span class="hlt">Antarctic</span> circumpolar current (ACC) in the <span class="hlt">ocean</span> play decisive roles in the climatic system of the mid- to high-latitude <span class="hlt">southern</span> hemisphere. Using the time-variable gravity data from the GRACE satellite mission, we find the link between the space-time variabilities of the ACC and the SAM. We calculate the empirical orthogonal functions (EOF) of the non-seasonal <span class="hlt">ocean</span> bottom pressure (OBP) field in the circum-<span class="hlt">Antarctic</span> seas from the GRACE data for the period from 2003 to 2015. We find that the leading EOF mode of the non-seasonal OBP represents a unison OBP oscillation around Antarctica with time history closely in pace with that of the SAM Index with a high correlation of 0.77. This OBP variation gives rise to a variation in the geostrophic flow field; the result for the same EOF mode shows heightened variations in the zonal velocity that resides primarily in the eastern hemispheric portion of the ACC and coincided geographically with the southernmost boundary of the ACC's main stream. Confirming previous oceanographic studies, these geodetic satellite results provide independent information toward better understanding of the ACC-SAM process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040040106','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040040106"><span>The Effects of Snow Depth Forcing on <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Sea Ice Simulations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Powel, Dylan C.; Markus, Thorsten; Stoessel, Achim</p> <p>2003-01-01</p> <p>The spatial and temporal distribution of snow on sea ice is an important factor for sea ice and climate models. First, it acts as an efficient insulator between the <span class="hlt">ocean</span> and the atmosphere, and second, snow is a source of fresh water for altering the already weak <span class="hlt">Southern</span> <span class="hlt">Ocean</span> stratification. For the <span class="hlt">Antarctic</span>, where the ice thickness is relatively thin, snow can impact the ice thickness in two ways: a) As mentioned above snow on sea ice reduces the <span class="hlt">ocean</span>-atmosphere heat flux and thus reduces freezing at the base of the ice flows; b) a heavy snow load can suppress the ice below sea level which causes flooding and, with subsequent freezing, a thickening of the sea ice (snow-to-ice conversion). In this paper, we compare different snow fall paramterizations (incl. the incorporation of satellite-derived snow depth) and study the effect on the sea ice using a sea ice model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27582222','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27582222"><span>Sea-ice transport driving <span class="hlt">Southern</span> <span class="hlt">Ocean</span> salinity and its recent trends.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Haumann, F Alexander; Gruber, Nicolas; Münnich, Matthias; Frenger, Ivy; Kern, Stefan</p> <p>2016-09-01</p> <p>Recent salinity changes in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> are among the most prominent signals of climate change in the global <span class="hlt">ocean</span>, yet their underlying causes have not been firmly established. Here we propose that trends in the northward transport of <span class="hlt">Antarctic</span> sea ice are a major contributor to these changes. Using satellite observations supplemented by sea-ice reconstructions, we estimate that wind-driven northward freshwater transport by sea ice increased by 20 ± 10 per cent between 1982 and 2008. The strongest and most robust increase occurred in the Pacific sector, coinciding with the largest observed salinity changes. We estimate that the additional freshwater for the entire northern sea-ice edge entails a freshening rate of -0.02 ± 0.01 grams per kilogram per decade in the surface and intermediate waters of the open <span class="hlt">ocean</span>, similar to the observed freshening. The enhanced rejection of salt near the coast of Antarctica associated with stronger sea-ice export counteracts the freshening of both continental shelf and newly formed bottom waters due to increases in glacial meltwater. Although the data sources underlying our results have substantial uncertainties, regional analyses and independent data from an atmospheric reanalysis support our conclusions. Our finding that northward sea-ice freshwater transport is also a key determinant of the mean salinity distribution in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> further underpins the importance of the sea-ice-induced freshwater flux. Through its influence on the density structure of the <span class="hlt">ocean</span>, this process has critical consequences for the global climate by affecting the exchange of heat, carbon and nutrients between the deep <span class="hlt">ocean</span> and surface waters.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850053015&hterms=worlds+oceans&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dworlds%2Boceans','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850053015&hterms=worlds+oceans&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dworlds%2Boceans"><span>Observing large-scale temporal variability of <span class="hlt">ocean</span> currents by satellite altimetry - With application to the <span class="hlt">Antarctic</span> circumpolar current</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fu, L.-L.; Chelton, D. B.</p> <p>1985-01-01</p> <p>A new method is developed for studying large-scale temporal variability of <span class="hlt">ocean</span> currents from satellite altimetric sea level measurements at intersections (crossovers) of ascending and descending orbit ground tracks. Using this method, sea level time series can be constructed from crossover sea level differences in small sample areas where altimetric crossovers are clustered. The method is applied to Seasat altimeter data to study the temporal evolution of the <span class="hlt">Antarctic</span> Circumpolar Current (ACC) over the 3-month Seasat mission (July-October 1978). The results reveal a generally eastward acceleration of the ACC around the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> with meridional disturbances which appear to be associated with bottom topographic features. This is the first direct observational evidence for large-scale coherence in the temporal variability of the ACC. It demonstrates the great potential of satellite altimetry for synoptic observation of temporal variability of the world <span class="hlt">ocean</span> circulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ACPD...1529125H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ACPD...1529125H"><span>Unexpectedly high ultrafine aerosol concentrations above East <span class="hlt">Antarctic</span> sea-ice</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Humphries, R. S.; Klekociuk, A. R.; Schofield, R.; Keywood, M.; Ward, J.; Wilson, S. R.</p> <p>2015-10-01</p> <p>The effect of aerosols on clouds and their radiative properties is one of the largest uncertainties in our understanding of radiative forcing. A recent study has concluded that better characterisation of pristine, natural aerosol processes leads to the largest reduction in these uncertainties. Antarctica, being far from anthropogenic activities, is an ideal location for the study of natural aerosol processes. Aerosol measurements in Antarctica are often limited to boundary layer air-masses at spatially sparse coastal and continental research stations, with only a handful of studies in the sea ice region. In this paper, the first observational study of sub-micron aerosols in the East <span class="hlt">Antarctic</span> sea ice region is presented. Measurements were conducted aboard the ice-breaker Aurora Australis in spring 2012 and found that boundary layer condensation nuclei (CN3) concentrations exhibited a five-fold increase moving across the Polar Front, with mean Polar Cell concentrations of 1130 cm-3 - higher than any observed elsewhere in the <span class="hlt">Antarctic</span> and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> region. The absence of evidence for aerosol growth suggested that nucleation was unlikely to be local. Air parcel trajectories indicated significant influence from the free troposphere above the <span class="hlt">Antarctic</span> continent, implicating this as the likely nucleation region for surface aerosol, a similar conclusion to previous <span class="hlt">Antarctic</span> aerosol studies. The highest aerosol concentrations were found to correlate with low pressure systems, suggesting that the passage of cyclones provided an accelerated pathway, delivering air-masses quickly from the free-troposphere to the surface. After descent from the <span class="hlt">Antarctic</span> free troposphere, trajectories suggest that sea ice boundary layer air-masses travelled equator-ward into the low albedo <span class="hlt">Southern</span> <span class="hlt">Ocean</span> region, transporting with them emissions and these aerosol nuclei where, after growth, may potentially impact on the region's radiative balance. The high aerosol concentrations and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.6402W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.6402W"><span>Eddy response to variable atmospheric forcing in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ward, M. L.; McC. Hogg, A.</p> <p>2009-04-01</p> <p>Satellite altimeter data of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (SO) reveal an anomalous peak in eddy kinetic energy (EKE) in the <span class="hlt">Antarctic</span> Circumpolar Current (ACC) in 2000-2002. This peak has been attributed to a delayed response to an earlier peak in the <span class="hlt">Southern</span> Annular Mode (SAM) and its associated circumpolar eastward winds that occurred around 1998, where the delay is due to the formation and adjustment of the eddy field associated with the increased winds (Meredith & Hogg, 2006). A more recent analysis reveals that the EKE response varies regionally, with the strongest response in the Pacific, and it has been suggested that this variability is due to the additional influence of ENSO. The 2000-2002 peak in EKE is therefore attributed to the coincident peak in SAM and ENSO 2-3 years earlier, and that the EKE response was weaker in past years when modes were out of phase (Morrow & Pasquet, 2008). We investigate this issue by applying SAM-like and ENSO-like wind forcings to Q-GCM, the eddy-resolving model used in Meredith & Hogg and configured for the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. We analyze the EKE response to each individual forcing as well as a simultaneous forcing of the two, both in and out of phase. From these results, we are able to quantify both the global and regional response to each forcing, and the degree to which each mode is responsible for the EKE strength and distribution across the ACC.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25875205','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25875205"><span>Sources and levels of ambient <span class="hlt">ocean</span> sound near the <span class="hlt">Antarctic</span> Peninsula.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dziak, Robert P; Bohnenstiehl, DelWayne R; Stafford, Kathleen M; Matsumoto, Haruyoshi; Park, Minkyu; Lee, Won Sang; Fowler, Matt J; Lau, Tai-Kwan; Haxel, Joseph H; Mellinger, David K</p> <p>2015-01-01</p> <p>Arrays of hydrophones were deployed within the Bransfield Strait and Scotia Sea (<span class="hlt">Antarctic</span> Peninsula region) from 2005 to 2009 to record ambient <span class="hlt">ocean</span> sound at frequencies of up to 125 and 500 Hz. Icequakes, which are broadband, short duration signals derived from fracturing of large free-floating icebergs, are a prominent feature of the <span class="hlt">ocean</span> soundscape. Icequake activity peaks during austral summer and is minimum during winter, likely following freeze-thaw cycles. Iceberg grounding and rapid disintegration also releases significant acoustic energy, equivalent to large-scale geophysical events. Overall ambient sound levels can be as much as ~10-20 dB higher in the open, deep <span class="hlt">ocean</span> of the Scotia Sea compared to the relatively shallow Bransfield Strait. Noise levels become lowest during the austral winter, as sea-ice cover suppresses wind and wave noise. Ambient noise levels are highest during austral spring and summer, as surface noise, ice cracking and biological activity intensifies. Vocalizations of blue (Balaenoptera musculus) and fin (B. physalus) whales also dominate the long-term spectra records in the 15-28 and 89 Hz bands. Blue whale call energy is a maximum during austral summer-fall in the Drake Passage and Bransfield Strait when ambient noise levels are a maximum and sea-ice cover is a minimum. Fin whale vocalizations were also most common during austral summer-early fall months in both the Bransfield Strait and Scotia Sea. The hydrophone data overall do not show sustained anthropogenic sources (ships and airguns), likely due to low coastal traffic and the typically rough weather and sea conditions of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4598877','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4598877"><span>Trends and variability of the atmosphere–<span class="hlt">ocean</span> turbulent heat flux in the extratropical <span class="hlt">Southern</span> Hemisphere</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Herman, Agnieszka</p> <p>2015-01-01</p> <p>Ocean–atmosphere interactions are complex and extend over a wide range of temporal and spatial scales. Among the key components of these interactions is the ocean–atmosphere (latent and sensible) turbulent heat flux (THF). Here, based on daily optimally-interpolated data from the extratropical <span class="hlt">Southern</span> Hemisphere (south of 30°S) from a period 1985–2013, we analyze short-term variability and trends in THF and variables influencing it. It is shown that, in spite of climate-change-related positive trends in surface wind speeds over large parts of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, the range of the THF variability has been decreasing due to decreasing air–water temperature and humidity differences. Occurrence frequency of very large heat flux events decreased accordingly. Remarkably, spectral analysis of the THF data reveals, in certain regions, robust periodicity at frequencies 0.03–0.04 day−1, corresponding exactly to frequencies of the baroclinic annular mode (BAM). Finally, it is shown that the THF is correlated with the position of the major fronts in sections of the <span class="hlt">Antarctic</span> Circumpolar Current where the fronts are not constrained by the bottom topography and can adjust their position to the atmospheric and <span class="hlt">oceanic</span> forcing, suggesting differential response of various sections of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> to the changing atmospheric forcing. PMID:26449323</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-eddies-in-the-southern-ocean_17078909501_o.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-eddies-in-the-southern-ocean_17078909501_o.html"><span>Eddies in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2015-04-08</p> <p>The cloud cover over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> occasionally parts as it did on January 1, 2015 just west of the Drake Passage where the VIIRS instrument on the Suomi NPP satellite glimpsed the above collection of <span class="hlt">ocean</span>-color delineated eddies which have diameters ranging from a couple of kilometers to a couple of hundred kilometers. Recent studies indicate that eddy activity has been increasing in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> with possible implications for climate change. Credit: NASA's <span class="hlt">Ocean</span>Color/Suomi NPP/VIIRS</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C53D..01N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C53D..01N"><span>Examining Differences in Arctic and <span class="hlt">Antarctic</span> Sea Ice Change</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nghiem, S. V.; Rigor, I. G.; Clemente-Colon, P.; Neumann, G.; Li, P.</p> <p>2015-12-01</p> <p>The paradox of the rapid reduction of Arctic sea ice versus the stability (or slight increase) of <span class="hlt">Antarctic</span> sea ice remains a challenge in the cryospheric science research community. Here we start by reviewing a number of explanations that have been suggested by different researchers and authors. One suggestion is that stratospheric ozone depletion may affect atmospheric circulation and wind patterns such as the <span class="hlt">Southern</span> Annular Mode, and thereby sustaining the <span class="hlt">Antarctic</span> sea ice cover. The reduction of salinity and density in the near-surface layer may weaken the convective mixing of cold and warmer waters, and thus maintaining regions of no warming around the <span class="hlt">Antarctic</span>. A decrease in sea ice growth may reduce salt rejection and upper-<span class="hlt">ocean</span> density to enhance thermohalocline stratification, and thus supporting <span class="hlt">Antarctic</span> sea ice production. Melt water from <span class="hlt">Antarctic</span> ice shelves collects in a cool and fresh surface layer to shield the surface <span class="hlt">ocean</span> from the warmer deeper waters, and thus leading to an expansion of <span class="hlt">Antarctic</span> sea ice. Also, wind effects may positively contribute to <span class="hlt">Antarctic</span> sea ice growth. Moreover, Antarctica lacks of additional heat sources such as warm river discharge to melt sea ice as opposed to the case in the Arctic. Despite of these suggested explanations, factors that can consistently and persistently maintains the stability of sea ice still need to be identified for the <span class="hlt">Antarctic</span>, which are opposed to factors that help accelerate sea ice loss in the Arctic. In this respect, using decadal observations from multiple satellite datasets, we examine differences in sea ice properties and distributions, together with dynamic and thermodynamic processes and interactions with land, <span class="hlt">ocean</span>, and atmosphere, causing differences in Arctic and <span class="hlt">Antarctic</span> sea ice change to contribute to resolving the Arctic-<span class="hlt">Antarctic</span> sea ice paradox.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17777827','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17777827"><span><span class="hlt">Antarctic</span> Glaciation during the Tertiary Recorded in Sub-<span class="hlt">Antarctic</span> Deep-Sea Cores.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Margolis, S V; Kennett, J P</p> <p>1970-12-04</p> <p>Study of 18 Cenozoic South Pacific deep-sea cores indicates an association of glacially derived ice-rafted sands and relatively low planktonic foraminiferal diversity with cooling of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> during the Lower Eocene, upper Middle Eocene, and Oligocene. Increased species diversity and reduction or absence of ice-rafted sands in Lower and Middle Miocene cores indicate a warming trend that ended in the Upper Miocene. <span class="hlt">Antarctic</span> continental glaciation appears to have prevailed throughout much of the Cenozoic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMGC13C0652T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMGC13C0652T"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> air-sea heat flux, SST spatial anomalies, and implications for multi-decadal upper <span class="hlt">ocean</span> heat content trends.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tamsitt, V. M.; Talley, L. D.; Mazloff, M. R.</p> <p>2014-12-01</p> <p>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> displays a zonal dipole (wavenumber one) pattern in sea surface temperature (SST), with a cool zonal anomaly in the Atlantic and Indian sectors and a warm zonal anomaly in the Pacific sector, associated with the large northward excursion of the Malvinas and southeastward flow of the <span class="hlt">Antarctic</span> Circumpolar Current (ACC). To the north of the cool Indian sector is the warm, narrow Agulhas Return Current (ARC). Air-sea heat flux is largely the inverse of this SST pattern, with <span class="hlt">ocean</span> heat gain in the Atlantic/Indian, cooling in the southeastward-flowing ARC, and cooling in the Pacific, based on adjusted fluxes from the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> State Estimate (SOSE), a ⅙° eddy permitting model constrained to all available in situ data. This heat flux pattern is dominated by turbulent heat loss from the <span class="hlt">ocean</span> (latent and sensible), proportional to perturbations in the difference between SST and surface air temperature, which are maintained by <span class="hlt">ocean</span> advection. Locally in the Indian sector, intense heat loss along the ARC is contrasted by <span class="hlt">ocean</span> heat gain of 0.11 PW south of the ARC. The IPCC AR5 50 year depth-averaged 0-700 m temperature trend shows surprising similarities in its spatial pattern, with upper <span class="hlt">ocean</span> warming in the ARC contrasted by cooling to the south. Using diagnosed heat budget terms from the most recent (June 2014) 6-year run of the SOSE we find that surface cooling in the ARC is balanced by heating from south-eastward advection by the current whereas heat gain in the ACC is balanced by cooling due to northward Ekman transport driven by strong westerly winds. These results suggest that spatial patterns in multi-decadal upper <span class="hlt">ocean</span> temperature trends depend on regional variations in upper <span class="hlt">ocean</span> dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998JMS....17..245S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998JMS....17..245S"><span>Primary productivity of the Palmer Long Term Ecological Research Area and the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, R. C.; Baker, K. S.; Byers, M. L.; Stammerjohn, S. E.</p> <p>1998-11-01</p> <p>A major objective of the Palmer Long Term Ecological Research (Palmer LTER) project is to obtain a comprehensive understanding of the various components of the <span class="hlt">Antarctic</span> marine ecosystem. Phytoplankton production plays a key role in this so-called high nutrient, low chlorophyll environment, and factors that regulate production include those that control cell growth (light, temperature, and nutrients) and those that control cell accumulation rate and hence population growth (water column stability, grazing, and sinking). Sea ice mediates several of these factors and frequently conditions the water column for a spring bloom which is characterized by a pulse of production restricted in both time and space. This study models the spatial and temporal variability of primary production within the Palmer LTER area west of the <span class="hlt">Antarctic</span> Peninsula and discusses this production in the context of historical data for the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Primary production for the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and the Palmer LTER area have been computed using both light-pigment production models [Smith, R.C., Bidigare, R.R., Prézelin, B.B., Baker, K.S., Brooks, J.M., 1987. Optical characterization of primary productivity across a coastal front. Mar. Biol. (96), 575-591; Bidigare, R.R., Smith, R.C., Baker, K.S., Marra, J., 1987. <span class="hlt">Oceanic</span> primary production estimates from measurements of spectral irradiance and pigment concentrations. Global Biogeochem. Cycles (1), 171-186; Morel, A., Berthon, J.F., 1989. Surface pigments, algal biomass profiles and potential production of the euphotic layer—relationships reinvestigated in view of remote-sensing applications. Limnol. Oceanogr. (34), 1545-1562] and an ice edge production model [Nelson, D.M., Smith, W.O., 1986. Phytoplankton bloom dynamics of the western Ross Sea ice edge: II. Mesoscale cycling of nitrogen and silicon. Deep-Sea Res. (33), 1389-1412; Wilson, D.L., Smith, W.O., Nelson, D.M., 1986. Phytoplankton bloom dynamics of the Western Ross Sea ice edge: I</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSHE44D1547S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSHE44D1547S"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> vertical iron fluxes; the <span class="hlt">ocean</span> model effect</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schourup-Kristensen, V.; Haucke, J.; Losch, M. J.; Wolf-Gladrow, D.; Voelker, C. D.</p> <p>2016-02-01</p> <p>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> plays a key role in the climate system, but commonly used large-scale <span class="hlt">ocean</span> general circulation biogeochemical models give different estimates of current and future <span class="hlt">Southern</span> <span class="hlt">Ocean</span> net primary and export production. The representation of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> iron sources plays an important role for the modeled biogeochemistry. Studies of the iron supply to the surface mixed layer have traditionally focused on the aeolian and sediment contributions, but recent work has highlighted the importance of the vertical supply from below. We have performed a model study in which the biogeochemical model REcoM2 was coupled to two different <span class="hlt">ocean</span> models, the Finite Element Sea-ice <span class="hlt">Ocean</span> Model (FESOM) and the MIT general circulation model (MITgcm) and analyzed the magnitude of the iron sources to the surface mixed layer from below in the two models. Our results revealed a remarkable difference in terms of mechanism and magnitude of transport. The mean iron supply from below in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> was on average four times higher in MITgcm than in FESOM and the dominant pathway was entrainment in MITgcm, whereas diffusion dominated in FESOM. Differences in the depth and seasonal amplitude of the mixed layer between the models affect on the vertical iron profile, the relative position of the base of the mixed layer and ferricline and thereby also on the iron fluxes. These differences contribute to differences in the phytoplankton composition in the two models, as well as in the timing of the onset of the spring bloom. The study shows that the choice of <span class="hlt">ocean</span> model has a significant impact on the iron supply to the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> mixed layer and thus on the modeled carbon cycle, with possible implications for model runs predicting the future carbon uptake in the region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170008477','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170008477"><span>Improving Our Understanding of <span class="hlt">Antarctic</span> Sea Ice with NASA's Operation IceBridge and the Upcoming ICESat-2 Mission</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Petty, Alek A.; Markus, Thorsten; Kurtz, Nathan T.</p> <p>2017-01-01</p> <p><span class="hlt">Antarctic</span> sea ice is a crucial component of the global climate system. Rapid sea ice production regimes around Antarctica feed the lower branch of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> overturning circulation through intense brine rejection and the formation of <span class="hlt">Antarctic</span> Bottom Water (e.g., Orsi et al. 1999; Jacobs 2004), while the northward transport and subsequent melt of <span class="hlt">Antarctic</span> sea ice drives the upper branch of the overturning circulation through freshwater input (Abernathy et al. 2016). Wind-driven trends in <span class="hlt">Antarctic</span> sea ice (Holland Kwok 2012) have likely increased the transport of freshwater away from the <span class="hlt">Antarctic</span> coastline, significantly altering the salinity distribution of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (Haumann et al. 2016). Conversely, weaker sea ice production and the lack of shelf water formation over the Amundsen and Bellingshausen shelf seas promote intrusion of warm Circumpolar Deep Water onto the continental shelf and the <span class="hlt">ocean</span>-driven melting of several ice shelves fringing the West <span class="hlt">Antarctic</span> Ice Sheet (e.g., Jacobs et al. 2011; Pritchard et al. 2012; Dutrieux et al. 2014). Sea ice conditions around Antarctica are also increasingly considered an important factor impacting local atmospheric conditions and the surface melting of <span class="hlt">Antarctic</span> ice shelves (e.g., Scambos et al. 2017). Sea ice formation around Antarctica is responsive to the strong regional variability in atmospheric forcing present around Antarctica, driving this bimodal variability in the behavior and properties of the underlying shelf seas (e.g., Petty et al. 2012; Petty et al. 2014).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006DSRI...53.1203H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006DSRI...53.1203H"><span>The seasonal succession of zooplankton in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> south of Australia, part II: The Sub-<span class="hlt">Antarctic</span> to Polar Frontal Zones</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hunt, Brian P. V.; Hosie, Graham W.</p> <p>2006-07-01</p> <p>Between October 2001 and March 2002 six transects were completed at monthly intervals in the Sub-<span class="hlt">Antarctic</span> Zone (SAZ) and Inter-Sub-<span class="hlt">Antarctic</span> Front Zone (ISAFZ)/Polar Frontal Zone (PFZ) in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> south of Australia. Zooplankton were collected with a Continuous Plankton Recorder and NORPAC net and multivariate analysis was used to analyse the seasonal succession of communities. Despite strong, seasonally consistent, biogeographic differences between the SAZ and ISAFZ/PFZ, community structure in all zones was dominated by a suite of common taxa. These included the ubiquitous Oithona similis, foraminiferans and appendicularians (Core taxa), occurring in >97% of samples and contributing an average of 75% to total sample abundance, and Calanus simillimus, Rhincalanus gigas, Ctenocalanus citer, Clausocalanus brevipes, Clausocalanus laticeps, Oithona frigida, Limacina spp. and chaetognaths (Summer taxa), present in >57% of samples and occurring at seasonally high densities. Because of the dominance of the Core and Summer taxa, the seasonal succession was most clearly evident as a change in zooplankton densities. In October densities averaged <15 ind m -3, rising to 52 ind m -3 (max=92 ind m -3) in November, and subsequently increasing slowly through to January (ave=115 ind m -3; max=255 ind m -3). Densities peaked abruptly in February (ave=634 ind m -3; max=1593 ind m -3), and remained relatively high in March (ave=193 ind m -3; max=789 ind m -3). A latitudinal lag in seasonal development was observed with peak densities occurring first in the SAZ (February) and then in the ISAFZ/PFZ (March). The seasonal community succession was strongly influenced by species population cycles. The role of zooplankton in biogeochemical cycling in the SAZ and ISAFZ/PFZ was discussed in the light of past sediment trap data collected from the study area.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GeoRL..45.1086K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GeoRL..45.1086K"><span>Contributions of Greenhouse Gas Forcing and the <span class="hlt">Southern</span> Annular Mode to Historical <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Surface Temperature Trends</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kostov, Yavor; Ferreira, David; Armour, Kyle C.; Marshall, John</p> <p>2018-01-01</p> <p>We examine the 1979-2014 <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (SO) sea surface temperature (SST) trends simulated in an ensemble of coupled general circulation models and evaluate possible causes of the models' inability to reproduce the observed 1979-2014 SO cooling. For each model we estimate the response of SO SST to step changes in greenhouse gas (GHG) forcing and in the seasonal indices of the <span class="hlt">Southern</span> Annular Mode (SAM). Using these step-response functions, we skillfully reconstruct the models' 1979-2014 SO SST trends. Consistent with the seasonal signature of the <span class="hlt">Antarctic</span> ozone hole and the seasonality of SO stratification, the summer and fall SAM exert a large impact on the simulated SO SST trends. We further identify conditions that favor multidecadal SO cooling: (1) a weak SO warming response to GHG forcing, (2) a strong multidecadal SO cooling response to a positive SAM trend, and (3) a historical SAM trend as strong as in observations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28135723','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28135723"><span>Vigorous lateral export of the meltwater outflow from beneath an <span class="hlt">Antarctic</span> ice shelf.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Garabato, Alberto C Naveira; Forryan, Alexander; Dutrieux, Pierre; Brannigan, Liam; Biddle, Louise C; Heywood, Karen J; Jenkins, Adrian; Firing, Yvonne L; Kimura, Satoshi</p> <p>2017-02-09</p> <p>The instability and accelerated melting of the <span class="hlt">Antarctic</span> Ice Sheet are among the foremost elements of contemporary global climate change. The increased freshwater output from Antarctica is important in determining sea level rise, the fate of <span class="hlt">Antarctic</span> sea ice and its effect on the Earth's albedo, ongoing changes in global deep-<span class="hlt">ocean</span> ventilation, and the evolution of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ecosystems and carbon cycling. A key uncertainty in assessing and predicting the impacts of <span class="hlt">Antarctic</span> Ice Sheet melting concerns the vertical distribution of the exported meltwater. This is usually represented by climate-scale models as a near-surface freshwater input to the <span class="hlt">ocean</span>, yet measurements around Antarctica reveal the meltwater to be concentrated at deeper levels. Here we use observations of the turbulent properties of the meltwater outflows from beneath a rapidly melting <span class="hlt">Antarctic</span> ice shelf to identify the mechanism responsible for the depth of the meltwater. We show that the initial ascent of the meltwater outflow from the ice shelf cavity triggers a centrifugal overturning instability that grows by extracting kinetic energy from the lateral shear of the background <span class="hlt">oceanic</span> flow. The instability promotes vigorous lateral export, rapid dilution by turbulent mixing, and finally settling of meltwater at depth. We use an idealized <span class="hlt">ocean</span> circulation model to show that this mechanism is relevant to a broad spectrum of <span class="hlt">Antarctic</span> ice shelves. Our findings demonstrate that the mechanism producing meltwater at depth is a dynamically robust feature of <span class="hlt">Antarctic</span> melting that should be incorporated into climate-scale models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.2366C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.2366C"><span>Interannual surface variability of the <span class="hlt">Southern</span> Pacific <span class="hlt">Ocean</span> in relation to the SAM pattern</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cotroneo, Yuri; Menna, Milena; Falco, Pierpaolo; Poulain, Pierre Marie</p> <p>2017-04-01</p> <p>Drifter and satellite data are used to define the response of the Pacific Sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (PSSO) to the large scale climatic pattern (<span class="hlt">Southern</span> Annular Mode index - SAMI) in the period 1995-2015. The SAMI, defined as the mean sea level pressure difference between the 40° S and 65°S latitudes (Marshall et al., 2003), affects the eddy activity of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and consequently the large-scale zonal transport in the <span class="hlt">Antarctic</span> Circumpolar Current (ACC; Meredith and Hoggs, 2006; Hogg et al., 2014). Drifter data were primarily corrected for the wind-induced slip and currents (Ekman), then used to estimate annual values of the Eddy Kinetic Energy (EKE) fields in bins of 2°x2° over the PSSO. Time series of the drifter EKEs were compared with the EKEs derived from altimeter data over the entire study area and with the temporal evolution of SAMI. A more quantitative evaluation of the surface eddy field response to the SAMI was performed counting the number and type (cyclonic or anticyclonic)of eddies produced in the whole PSSO and in correspondence of the Sub-<span class="hlt">Antarctic</span> Front (SAF) and Polar Front (PF). The mean latitude of each front was determined using thermal criteria applied to a long time series of in situ XBT data collected by the Italian <span class="hlt">Antarctic</span> Programme along the track between New Zealand and Antarctica from 1994 to 2016. Eddy counting was based on the results of the identification and tracking method performed by Chelton et al. (2011), retaining only those eddies with lifetimes of 4 weeks or longer. The drifter derived EKE shows a similar and quicker response to the SAMI variability with respect to the altimetry derived EKE; the time lag is of one year for drifters and of two years for the altimetry. Both the datasets reveal an anomalous behaviour of the EKE during the period 2003-2006. The SAMI variability induces a specific effect on the different frontal zones with changes in the number and type of eddy generated. Moreover the anomalous</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeCoA.125..653Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeCoA.125..653Z"><span>Biogeochemical cycling of zinc and its isotopes in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhao, Y.; Vance, D.; Abouchami, W.; de Baar, H. J. W.</p> <p>2014-01-01</p> <p>We report Zn concentration and isotope data for seawater samples from the Atlantic sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, collected during the IPY/GEOTRACES ANT-XXIV/III cruise along the Greenwich Zero Meridian. Data are reported for the full depth range of the water column at three stations, as well as a transect of surface samples, using a new analytical approach that is presented in detail here. Zn concentrations increase with depth, though due to proximity to upwelling sites, surface concentrations are not as low as in some parts of the <span class="hlt">ocean</span> such as further northward into the Sub-<span class="hlt">Antarctic</span> Zone. For two depth profiles south of the Polar Front Zone, the physical stratification of the upper water column is reflected in sudden near-surface changes in Zn concentration with depth. In contrast, beneath 100-300 m Zn concentrations barely change with depth. Zn isotopic data beneath 1000 m, for the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> data presented here as well as published data from the North Atlantic and North Pacific, are strikingly homogeneous, with an average δ66Zn = +0.53 ± 0.14‰ (2SD, 2SE = 0.03, n = 21). The surface <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is more variable, with δ66Zn ranging from 0.07‰ to 0.80‰. Between the two is a thin horizon at 40-80 m which, in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> as well as the North Atlantic and North Pacific, is characterised by distinctly light isotopic signatures, with δ66Zn about 0.3‰ lower than surface waters. Strong correlations between Si and Zn concentrations seen here and elsewhere, coupled to the lack of any systematic relationship between Si and Zn isotopes in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, suggest that the removal of Zn associated with diatom opal involves little or no isotopic fractionation. Regeneration of this Zn also explains the homogeneous Zn isotopic composition of the global deep <span class="hlt">ocean</span> so far sampled. However, the low Zn content of opal requires that deep <span class="hlt">ocean</span> Zn does not directly come from the opal phase itself, but rather from associated organic material external to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991EOSTr..72Q..84.','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991EOSTr..72Q..84."><span>AGU honored for <span class="hlt">Antarctic</span> book</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p></p> <p></p> <p>AGU has won an honorable mention award at the Fifteenth Annual Awards Program for Excellence in Professional and Scholarly Publishing sponsored by the Association of American Publishers for the book Volcanoes of the <span class="hlt">Antarctic</span> Plate and <span class="hlt">Southern</span> <span class="hlt">Oceans</span>. The book is part of AGU's <span class="hlt">Antarctic</span> Research Series, an outgrowth of research done during the International Geophysical Year that was begun in 1963 with a grant from the National Science Foundation. The award was presented at the AAP Annual Awards Dinner on February 6 at the Ritz-Carlton Hotel in Washington, D.C. The award consists of a medallion and a plate on which the names of the publisher, title, and authors are engraved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1811271M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1811271M"><span>The Deep South Clouds & Aerosols project: Improving the modelling of clouds in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> region</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Morgenstern, Olaf; McDonald, Adrian; Harvey, Mike; Davies, Roger; Katurji, Marwan; Varma, Vidya; Williams, Jonny</p> <p>2016-04-01</p> <p><span class="hlt">Southern</span>-Hemisphere climate projections are subject to persistent climate model biases affecting the large majority of contemporary climate models, which degrade the reliability of these projections, particularly at the regional scale. <span class="hlt">Southern</span>-Hemisphere specific problems include the fact that satellite-based observations comparisons with model output indicate that cloud occurrence above the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is substantially underestimated, with consequences for the radiation balance, sea surface temperatures, sea ice, and the position of storm tracks. The <span class="hlt">Southern-Ocean</span> and <span class="hlt">Antarctic</span> region is generally characterized by an acute paucity of surface-based and airborne observations, further complicating the situation. In recognition of this and other <span class="hlt">Southern</span>-Hemisphere specific problems with climate modelling, the New Zealand Government has launched the Deep South National Science Challenge, whose purpose is to develop a new Earth System Model which reduces these very large radiative forcing problems associated with erroneous clouds. The plan is to conduct a campaign of targeted observations in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> region, leveraging off international measurement campaigns in this area, and using these and existing measurements of cloud and aerosol properties to improve the representation of clouds in the nascent New Zealand Earth System Model. Observations and model development will target aerosol physics and chemistry, particularly sulphate, sea salt, and non-sulphate organic aerosol, its interactions with clouds, and cloud microphysics. The hypothesis is that the cloud schemes in most GCMs are trained on Northern-Hemisphere data characterized by substantial anthropogenic or terrestrial aerosol-related influences which are almost completely absent in the Deep South.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRC..123.1533B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRC..123.1533B"><span>Three-Dimensional Ageostrophic Motion and Water Mass Subduction in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Buongiorno Nardelli, B.; Mulet, S.; Iudicone, D.</p> <p>2018-02-01</p> <p>Vertical velocities at the <span class="hlt">ocean</span> mesoscale are several orders of magnitude smaller than corresponding horizontal flows, making their direct monitoring a still unsolved challenge. Vertical motion is generally retrieved indirectly by applying diagnostic equations to observation-based fields. The most common approach relies on the solution of an adiabatic version of the Omega equation, neglecting the ageostrophic secondary circulation driven by frictional effects and turbulent mixing in the boundary layers. Here we apply a diabatic semigeostrophic diagnostic model to two different 3-D reconstructions covering the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> during the period 2010-2012. We incorporate the effect of vertical mixing through a modified K-profile parameterization and using ERA-interim data, and perform an indirect validation of the ageostrophic circulation with independent drifter observations. Even if horizontal gradients and associated vertical flow are likely underestimated at 1/4° × 1/4° resolution, the exercise provides an unprecedented relative quantification of the contribution of vertical mixing and adiabatic internal dynamics on the vertical exchanges along the <span class="hlt">Antarctic</span> Circumpolar Current. Kinematic estimates of subduction rates show the destruction of poleward flowing waters lighter than 26.6 kg/m3 (14 ÷ 15 Sv) and two main positive bands associated with the <span class="hlt">Antarctic</span> Intermediate Water (7 ÷ 11 Sv) and Sub-<span class="hlt">Antarctic</span> Mode Waters (4 ÷ 7 Sv) formation, while Circumpolar Deep Water upwelling attains around 3 ÷ 6 Sv. Diabatic and adiabatic terms force distinct spatial responses and vertical velocity magnitudes along the water column and the restratifying effect of adiabatic internal dynamics due to mesoscale eddies is shown to at least partly compensate the contribution of wind-driven vertical exchanges to net subduction.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.9186V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.9186V"><span>The impact of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> gateways on the Cenozoic climate evolution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>von der Heydt, Anna; Viebahn, Jan; Dijkstra, Henk</p> <p>2016-04-01</p> <p>During the Cenozoic period, which covers the last 65 Million (Ma) years, Earth's climate has undergone a major long-term transition from warm "greenhouse" to colder "icehouse" conditions with extensive ice sheets in the polar regions of both hemispheres. On the very long term the gradual cooling may be seen as response to the overall slowly decreasing atmospheric CO2-concentration due to weathering processes in the Earth System, however, continental geometry has changed considerably over this period and the long-term gradual trend was interrupted, by several rapid transitions as well as periods where temperature and greenhouse gas concentrations seem to be decoupled. The Eocene-Oligocene boundary (˜34 Ma, E/O) and mid-Miocene climatic transition (˜13 Ma, MCT) reflect major phases of <span class="hlt">Antarctic</span> ice sheet build-up and global climate cooling, while Northern Hemisphere ice sheets developed much later, most likely at the Pliocene-Pleistocene transition (˜2.7Ma). Thresholds in atmospheric CO2-concentration together with feedback mechanisms related to land ice formation are now among the favoured mechanisms of these climatic transitions, while the long-proposed <span class="hlt">ocean</span> circulation changes caused by opening of tectonic gateways seem to play a less direct role. The opening of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> gateways, notably the Drake Passage and the Tasman Gateway as well as the northward movement of Australia over this long time period, however, has eventually led to the development of today's strongest <span class="hlt">ocean</span> current, the <span class="hlt">Antarctic</span> Circumpolar Current (ACC), playing a major role in the transport properties of the global <span class="hlt">ocean</span> circulation. The overall state of the global <span class="hlt">ocean</span> circulation, therefore, preconditions the climate system to dramatic events such as major ice sheet formation. Here, we present results of a state-of-the art global climate model (CESM) under various continental configurations: (i) present day geometry, (ii) present day geometry with a closed Drake Passage and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4397061','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4397061"><span>Sources and Levels of Ambient <span class="hlt">Ocean</span> Sound near the <span class="hlt">Antarctic</span> Peninsula</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dziak, Robert P.; Bohnenstiehl, DelWayne R.; Stafford, Kathleen M.; Matsumoto, Haruyoshi; Park, Minkyu; Lee, Won Sang; Fowler, Matt J.; Lau, Tai-Kwan; Haxel, Joseph H.; Mellinger, David K.</p> <p>2015-01-01</p> <p>Arrays of hydrophones were deployed within the Bransfield Strait and Scotia Sea (<span class="hlt">Antarctic</span> Peninsula region) from 2005 to 2009 to record ambient <span class="hlt">ocean</span> sound at frequencies of up to 125 and 500 Hz. Icequakes, which are broadband, short duration signals derived from fracturing of large free-floating icebergs, are a prominent feature of the <span class="hlt">ocean</span> soundscape. Icequake activity peaks during austral summer and is minimum during winter, likely following freeze-thaw cycles. Iceberg grounding and rapid disintegration also releases significant acoustic energy, equivalent to large-scale geophysical events. Overall ambient sound levels can be as much as ~10–20 dB higher in the open, deep <span class="hlt">ocean</span> of the Scotia Sea compared to the relatively shallow Bransfield Strait. Noise levels become lowest during the austral winter, as sea-ice cover suppresses wind and wave noise. Ambient noise levels are highest during austral spring and summer, as surface noise, ice cracking and biological activity intensifies. Vocalizations of blue (Balaenoptera musculus) and fin (B. physalus) whales also dominate the long-term spectra records in the 15–28 and 89 Hz bands. Blue whale call energy is a maximum during austral summer-fall in the Drake Passage and Bransfield Strait when ambient noise levels are a maximum and sea-ice cover is a minimum. Fin whale vocalizations were also most common during austral summer-early fall months in both the Bransfield Strait and Scotia Sea. The hydrophone data overall do not show sustained anthropogenic sources (ships and airguns), likely due to low coastal traffic and the typically rough weather and sea conditions of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. PMID:25875205</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1184780-sources-levels-ambient-ocean-sound-near-antarctic-peninsula','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1184780-sources-levels-ambient-ocean-sound-near-antarctic-peninsula"><span>Sources and levels of ambient <span class="hlt">ocean</span> sound near the <span class="hlt">antarctic</span> peninsula</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Dziak, Robert P.; Bohnenstiehl, DelWayne R.; Stafford, Kathleen M.; ...</p> <p>2015-04-14</p> <p>Arrays of hydrophones were deployed within the Bransfield Strait and Scotia Sea (<span class="hlt">Antarctic</span> Peninsula region) from 2005 to 2009 to record ambient <span class="hlt">ocean</span> sound at frequencies of up to 125 and 500 Hz. Icequakes, which are broadband, short duration signals derived from fracturing of large free-floating icebergs, are a prominent feature of the <span class="hlt">ocean</span> soundscape. Icequake activity peaks during austral summer and is minimum during winter, likely following freeze-thaw cycles. Iceberg grounding and rapid disintegration also releases significant acoustic energy, equivalent to large-scale geophysical events. Overall ambient sound levels can be as much as ~10–20 dB higher in the open,more » deep <span class="hlt">ocean</span> of the Scotia Sea compared to the relatively shallow Bransfield Strait. Noise levels become lowest during the austral winter, as sea-ice cover suppresses wind and wave noise. Ambient noise levels are highest during austral spring and summer, as surface noise, ice cracking and biological activity intensifies. Vocalizations of blue ( Balaenoptera musculus) and fin ( B. physalus) whales also dominate the long-term spectra records in the 15–28 and 89 Hz bands. Blue whale call energy is a maximum during austral summer-fall in the Drake Passage and Bransfield Strait when ambient noise levels are a maximum and sea-ice cover is a minimum. Fin whale vocalizations were also most common during austral summer-early fall months in both the Bransfield Strait and Scotia Sea. The hydrophone data overall do not show sustained anthropogenic sources (ships and airguns), likely due to low coastal traffic and the typically rough weather and sea conditions of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28280544','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28280544"><span>The influence of sea ice, wind speed and marine mammals on <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ambient sound.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Menze, Sebastian; Zitterbart, Daniel P; van Opzeeland, Ilse; Boebel, Olaf</p> <p>2017-01-01</p> <p>This paper describes the natural variability of ambient sound in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, an acoustically pristine marine mammal habitat. Over a 3-year period, two autonomous recorders were moored along the Greenwich meridian to collect underwater passive acoustic data. Ambient sound levels were strongly affected by the annual variation of the sea-ice cover, which decouples local wind speed and sound levels during austral winter. With increasing sea-ice concentration, area and thickness, sound levels decreased while the contribution of distant sources increased. Marine mammal sounds formed a substantial part of the overall acoustic environment, comprising calls produced by <span class="hlt">Antarctic</span> blue whales ( Balaenoptera musculus intermedia ), fin whales ( Balaenoptera physalus ), <span class="hlt">Antarctic</span> minke whales ( Balaenoptera bonaerensis ) and leopard seals ( Hydrurga leptonyx ). The combined sound energy of a group or population vocalizing during extended periods contributed species-specific peaks to the ambient sound spectra. The temporal and spatial variation in the contribution of marine mammals to ambient sound suggests annual patterns in migration and behaviour. The <span class="hlt">Antarctic</span> blue and fin whale contributions were loudest in austral autumn, whereas the <span class="hlt">Antarctic</span> minke whale contribution was loudest during austral winter and repeatedly showed a diel pattern that coincided with the diel vertical migration of zooplankton.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017RSOS....460370M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017RSOS....460370M"><span>The influence of sea ice, wind speed and marine mammals on <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ambient sound</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Menze, Sebastian; Zitterbart, Daniel P.; van Opzeeland, Ilse; Boebel, Olaf</p> <p>2017-01-01</p> <p>This paper describes the natural variability of ambient sound in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, an acoustically pristine marine mammal habitat. Over a 3-year period, two autonomous recorders were moored along the Greenwich meridian to collect underwater passive acoustic data. Ambient sound levels were strongly affected by the annual variation of the sea-ice cover, which decouples local wind speed and sound levels during austral winter. With increasing sea-ice concentration, area and thickness, sound levels decreased while the contribution of distant sources increased. Marine mammal sounds formed a substantial part of the overall acoustic environment, comprising calls produced by <span class="hlt">Antarctic</span> blue whales (Balaenoptera musculus intermedia), fin whales (Balaenoptera physalus), <span class="hlt">Antarctic</span> minke whales (Balaenoptera bonaerensis) and leopard seals (Hydrurga leptonyx). The combined sound energy of a group or population vocalizing during extended periods contributed species-specific peaks to the ambient sound spectra. The temporal and spatial variation in the contribution of marine mammals to ambient sound suggests annual patterns in migration and behaviour. The <span class="hlt">Antarctic</span> blue and fin whale contributions were loudest in austral autumn, whereas the <span class="hlt">Antarctic</span> minke whale contribution was loudest during austral winter and repeatedly showed a diel pattern that coincided with the diel vertical migration of zooplankton.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5319310','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5319310"><span>The influence of sea ice, wind speed and marine mammals on <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ambient sound</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>van Opzeeland, Ilse; Boebel, Olaf</p> <p>2017-01-01</p> <p>This paper describes the natural variability of ambient sound in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, an acoustically pristine marine mammal habitat. Over a 3-year period, two autonomous recorders were moored along the Greenwich meridian to collect underwater passive acoustic data. Ambient sound levels were strongly affected by the annual variation of the sea-ice cover, which decouples local wind speed and sound levels during austral winter. With increasing sea-ice concentration, area and thickness, sound levels decreased while the contribution of distant sources increased. Marine mammal sounds formed a substantial part of the overall acoustic environment, comprising calls produced by <span class="hlt">Antarctic</span> blue whales (Balaenoptera musculus intermedia), fin whales (Balaenoptera physalus), <span class="hlt">Antarctic</span> minke whales (Balaenoptera bonaerensis) and leopard seals (Hydrurga leptonyx). The combined sound energy of a group or population vocalizing during extended periods contributed species-specific peaks to the ambient sound spectra. The temporal and spatial variation in the contribution of marine mammals to ambient sound suggests annual patterns in migration and behaviour. The <span class="hlt">Antarctic</span> blue and fin whale contributions were loudest in austral autumn, whereas the <span class="hlt">Antarctic</span> minke whale contribution was loudest during austral winter and repeatedly showed a diel pattern that coincided with the diel vertical migration of zooplankton. PMID:28280544</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010028707','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010028707"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> Climate and Sea Ice Anomalies Associated with the <span class="hlt">Southern</span> Oscillation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kwok, R.; Comiso, J. C.</p> <p>2001-01-01</p> <p>The anomalies in the climate and sea ice cover of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and their relationships with the <span class="hlt">Southern</span> Oscillation (SO) are investigated using a 17-year of data set from 1982 through 1998. We correlate the polar climate anomalies with the <span class="hlt">Southern</span> Oscillation index (SOI) and examine the composites of these anomalies under the positive (SOI > 0), neutral (0 > SOI > -1), and negative (SOI < -1) phases of SOL The climate data set consists of sea-level pressure, wind, surface air temperature, and sea surface temperature fields, while the sea ice data set describes its extent, concentration, motion, and surface temperature. The analysis depicts, for the first time, the spatial variability in the relationship of the above variables and the SOL The strongest correlation between the SOI and the polar climate anomalies are found in the Bellingshausen, Amundsen and Ross sea sectors. The composite fields reveal anomalies that are organized in distinct large-scale spatial patterns with opposing polarities at the two extremes of SOI, and suggest oscillating climate anomalies that are closely linked to the SO. Within these sectors, positive (negative) phases of the SOI are generally associated with lower (higher) sea-level pressure, cooler (warmer) surface air temperature, and cooler (warmer) sea surface temperature in these sectors. Associations between these climate anomalies and the behavior of the <span class="hlt">Antarctic</span> sea ice cover are clearly evident. Recent anomalies in the sea ice cover that are apparently associated with the SOI include: the record decrease in the sea ice extent in the Bellingshausen Sea from mid- 1988 through early 199 1; the relationship between Ross Sea SST and ENSO signal, and reduced sea ice concentration in the Ross Sea; and, the shortening of the ice season in the eastern Ross Sea, Amundsen Sea, far western Weddell Sea, and the lengthening of the ice season in the western Ross Sea, Bellingshausen Sea and central Weddell Sea gyre over the period 1988</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23874794','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23874794"><span>Mitochondrial acclimation capacities to <span class="hlt">ocean</span> warming and acidification are limited in the <span class="hlt">antarctic</span> Nototheniid Fish, Notothenia rossii and Lepidonotothen squamifrons.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Strobel, Anneli; Graeve, Martin; Poertner, Hans O; Mark, Felix C</p> <p>2013-01-01</p> <p><span class="hlt">Antarctic</span> notothenioid fish are characterized by their evolutionary adaptation to the cold, thermostable <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, which is associated with unique physiological adaptations to withstand the cold and reduce energetic requirements but also entails limited compensation capacities to environmental change. This study compares the capacities of mitochondrial acclimation to <span class="hlt">ocean</span> warming and acidification between the <span class="hlt">Antarctic</span> nototheniid Notothenia rossii and the sub-<span class="hlt">Antarctic</span> Lepidonotothen squamifrons, which share a similar ecology, but different habitat temperatures. After acclimation of L. squamifrons to 9°C and N. rossii to 7°C (normocapnic/hypercapnic, 0.2 kPa CO2/2000 ppm CO2) for 4-6 weeks, we compared the capacities of their mitochondrial respiratory complexes I (CI) and II (CII), their P/O ratios (phosphorylation efficiency), proton leak capacities and mitochondrial membrane fatty acid compositions. Our results reveal reduced CII respiration rates in warm-acclimated L. squamifrons and cold hypercapnia-acclimated N. rossii. Generally, L. squamifrons displayed a greater ability to increase CI contribution during acute warming and after warm-acclimation than N. rossii. Membrane unsaturation was not altered by warm or hypercapnia-acclimation in both species, but membrane fatty acids of warm-acclimated L. squamifrons were less saturated than in warm normocapnia-/hypercapnia-acclimated N. rossii. Proton leak capacities were not affected by warm or hypercapnia-acclimation of N. rossii. We conclude that an acclimatory response of mitochondrial capacities may include higher thermal plasticity of CI supported by enhanced utilization of anaplerotic substrates (via oxidative decarboxylation reactions) feeding into the citrate cycle. L. squamifrons possesses higher relative CI plasticities than N. rossii, which may facilitate the usage of energy efficient NADH-related substrates under conditions of elevated energy demand, possibly induced by <span class="hlt">ocean</span> warming and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006GeoRL..3319701F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006GeoRL..3319701F"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> warming due to human influence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fyfe, John C.</p> <p>2006-10-01</p> <p>I show that the latest series of climate models reproduce the observed mid-depth <span class="hlt">Southern</span> <span class="hlt">Ocean</span> warming since the 1950s if they include time-varying changes in anthropogenic greenhouse gases, sulphate aerosols and volcanic aerosols in the Earth's atmosphere. The remarkable agreement between observations and state-of-the art climate models suggests significant human influence on <span class="hlt">Southern</span> <span class="hlt">Ocean</span> temperatures. I also show that climate models that do not include volcanic aerosols produce mid-depth <span class="hlt">Southern</span> <span class="hlt">Ocean</span> warming that is nearly double that produced by climate models that do include volcanic aerosols. This implies that the full effect of human-induced warming of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> may yet to be realized.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70018602','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70018602"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> monthly wave fields for austral winters 1985-1988 by Geosat radar altimeter</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Josberger, E.G.; Mognard, N.M.</p> <p>1996-01-01</p> <p>Four years of monthly averaged wave height fields for the austral winters 19851988 derived from the Geosat altimeter data show a spatial variability of the scale of 500-1000 km that varies monthly and annually. This variability is superimposed on the zonal patterns surrounding the <span class="hlt">Antarctic</span> continent and characteristic of the climatology derived from the U.S. Navy [1992] Marine Climatic Atlas of the World. The location and the intensity of these large-scale features, which are not found in the climatological fields, exhibit strong monthly and yearly variations. A global underestimation of the climatological mean wave heights by more than l m is also found over large regions of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. The largest monthly averaged significant wave heights are above 5 m and are found during August of every year in the Indian <span class="hlt">Ocean</span>, south of 40??S. The monthly wave fields show more variability in the Atlantic and Pacific <span class="hlt">Oceans</span> than in the Indian <span class="hlt">Ocean</span>. The Seasat data from 1978 and the Geosat data from 1985 and 1988 show an eastward rotation of the largest wave heights. However, this rotation is absent in 1986 and 1987; the former was a year of unusually low sea states, and the latter was a year of unusually high sea states, which suggests a link to the El Nin??o-<span class="hlt">Southern</span> Oscillation event of 1986. Copyright 1996 by the American Geophysical Union.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5472753','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5472753"><span>The influence of <span class="hlt">Antarctic</span> subglacial volcanism on the global iron cycle during the Last Glacial Maximum</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Frisia, Silvia; Weyrich, Laura S.; Hellstrom, John; Borsato, Andrea; Golledge, Nicholas R.; Anesio, Alexandre M.; Bajo, Petra; Drysdale, Russell N.; Augustinus, Paul C.; Rivard, Camille; Cooper, Alan</p> <p>2017-01-01</p> <p>Marine sediment records suggest that episodes of major atmospheric CO2 drawdown during the last glacial period were linked to iron (Fe) fertilization of subantarctic surface waters. The principal source of this Fe is thought to be dust transported from <span class="hlt">southern</span> mid-latitude deserts. However, uncertainty exists over contributions to CO2 sequestration from complementary Fe sources, such as the <span class="hlt">Antarctic</span> ice sheet, due to the difficulty of locating and interrogating suitable archives that have the potential to preserve such information. Here we present petrographic, geochemical and microbial DNA evidence preserved in precisely dated subglacial calcites from close to the East <span class="hlt">Antarctic</span> Ice-Sheet margin, which together suggest that volcanically-induced drainage of Fe-rich waters during the Last Glacial Maximum could have reached the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Our results support a significant contribution of <span class="hlt">Antarctic</span> volcanism to subglacial transport and delivery of nutrients with implications on <span class="hlt">ocean</span> productivity at peak glacial conditions. PMID:28598412</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17553770','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17553770"><span>Environmental forcing and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> marine predator populations: effects of climate change and variability.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Trathan, P N; Forcada, J; Murphy, E J</p> <p>2007-12-29</p> <p>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is a major component within the global <span class="hlt">ocean</span> and climate system and potentially the location where the most rapid climate change is most likely to happen, particularly in the high-latitude polar regions. In these regions, even small temperature changes can potentially lead to major environmental perturbations. Climate change is likely to be regional and may be expressed in various ways, including alterations to climate and weather patterns across a variety of time-scales that include changes to the long interdecadal background signals such as the development of the El Niño-<span class="hlt">Southern</span> Oscillation (ENSO). Oscillating climate signals such as ENSO potentially provide a unique opportunity to explore how biological communities respond to change. This approach is based on the premise that biological responses to shorter-term sub-decadal climate variability signals are potentially the best predictor of biological responses over longer time-scales. Around the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, marine predator populations show periodicity in breeding performance and productivity, with relationships with the environment driven by physical forcing from the ENSO region in the Pacific. Wherever examined, these relationships are congruent with mid-trophic-level processes that are also correlated with environmental variability. The short-term changes to ecosystem structure and function observed during ENSO events herald potential long-term changes that may ensue following regional climate change. For example, in the South Atlantic, failure of <span class="hlt">Antarctic</span> krill recruitment will inevitably foreshadow recruitment failures in a range of higher trophic-level marine predators. Where predator species are not able to accommodate by switching to other prey species, population-level changes will follow. The <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, though oceanographically interconnected, is not a single ecosystem and different areas are dominated by different food webs. Where species occupy different positions in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26896669','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26896669"><span>Penguins as bioindicators of mercury contamination in the <span class="hlt">southern</span> Indian <span class="hlt">Ocean</span>: geographical and temporal trends.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Carravieri, Alice; Cherel, Yves; Jaeger, Audrey; Churlaud, Carine; Bustamante, Paco</p> <p>2016-06-01</p> <p>Penguins have been recently identified as useful bioindicators of mercury (Hg) transfer to food webs in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> over different spatial and temporal scales. Here, feather Hg concentrations were measured in adults and chicks of all the seven penguin species breeding in the <span class="hlt">southern</span> Indian <span class="hlt">Ocean</span>, over a large latitudinal gradient spanning <span class="hlt">Antarctic</span>, subantarctic and subtropical sites. Hg was also measured in feathers of museum specimens of penguins collected at the same sites in the 1950s and 1970s. Our aim was to evaluate geographical and historical variations in Hg transfer to penguins, while accounting for feeding habits by using the stable isotope technique (δ(13)C, habitat; δ(15)N, diet/trophic level). Adult feather Hg concentrations in contemporary individuals ranged from 0.7 ± 0.2 to 5.9 ± 1.9 μg g(-1) dw in Adélie and gentoo penguins, respectively. Inter-specific differences in Hg accumulation were strong among both adults and chicks, and mainly linked to feeding habits. Overall, penguin species that feed in <span class="hlt">Antarctic</span> waters had lower feather Hg concentrations than those that feed in subantarctic and subtropical waters, irrespective of age class and dietary group, suggesting different Hg incorporation into food webs depending on the water mass. While accounting for feeding habits, we detected different temporal variations in feather Hg concentrations depending on species. Notably, the subantarctic gentoo and macaroni penguins had higher Hg burdens in the contemporary rather than in the historical sample, despite similar or lower trophic levels, respectively. Whereas increases in Hg deposition have been recently documented in the <span class="hlt">Southern</span> Hemisphere, future monitoring is highly needed to confirm or not this temporal trend in penguins, especially in the context of actual changing Hg emission patterns and global warming. Copyright © 2016. Published by Elsevier Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A11D1910B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A11D1910B"><span>The Role of <span class="hlt">Ocean</span> Eddies in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Response to Observed Greenhouse Gas Forcing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bilgen, S. I.; Kirtman, B. P.</p> <p>2017-12-01</p> <p>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (SO) is crucial to understanding the possible future response to a changing climate. This is a principal region where energy is conveyed to the <span class="hlt">ocean</span> by the westerly winds and it is here that mesoscale <span class="hlt">ocean</span> eddies field dominate meridional heat and momentum transport. Compared to the Arctic, the <span class="hlt">Antarctic</span> and the surrounding SO have a "delayed warming" anthropogenic greenhouse gas (GHG) response. Understanding the role of the <span class="hlt">ocean</span> dynamics in modulating the mesoscale atmosphere-<span class="hlt">ocean</span> interactions in the SO in a fully coupled regime is crucial to efforts aimed at predicting the consequences of the warming and variability to the climate system. The response of model run at multiple resolutions (eddy permitting, eddy resolving) to both GHG forcing and historical forcing are examined in NCAR CCSM4 with four experiments. The first simulation, 0.5° atmosphere coupled to <span class="hlt">ocean</span> and sea ice components with 1° resolution (LR). The second simulation uses the identical atmospheric model but coupled to 0.1° <span class="hlt">ocean</span> and sea ice component models (HR). For the third and fourth experiments, the global <span class="hlt">ocean</span> is simulated for LR an HR models, and a climate change scenario are produced by applying a fixed (present-day) CO2 concentration. The analysis focuses on the last 55 years of two individual 155 year simulations. We discuss results from a set of state-of-art model experiments in comparison with observational estimates and explore mechanisms by examining sea surface temperature, westerly winds, surface heat flux, <span class="hlt">ocean</span> heat transport. In LR simulations, the patterns and mechanisms of SO changes under GHG forcing are similar to those over the historical period: warming is damped southward of the ACC and enhanced to the north, however major changes between the HR simulations are explored. We find that in recent decades the <span class="hlt">Southern</span> Annual Mode has shown a distinct upward trend, the result of an anthropogenic global warming. Also, HR simulations show that</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRC..123.1994T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRC..123.1994T"><span>Transformation of Deep Water Masses Along Lagrangian Upwelling Pathways in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tamsitt, V.; Abernathey, R. P.; Mazloff, M. R.; Wang, J.; Talley, L. D.</p> <p>2018-03-01</p> <p>Upwelling of northern deep waters in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is fundamentally important for the closure of the global meridional overturning circulation and delivers carbon and nutrient-rich deep waters to the sea surface. We quantify water mass transformation along upwelling pathways originating in the Atlantic, Indian, and Pacific and ending at the surface of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> using Lagrangian trajectories in an eddy-permitting <span class="hlt">ocean</span> state estimate. Recent related work shows that upwelling in the interior below about 400 m depth is localized at hot spots associated with major topographic features in the path of the <span class="hlt">Antarctic</span> Circumpolar Current, while upwelling through the surface layer is more broadly distributed. In the <span class="hlt">ocean</span> interior upwelling is largely isopycnal; Atlantic and to a lesser extent Indian Deep Waters cool and freshen while Pacific deep waters are more stable, leading to a homogenization of water mass properties. As upwelling water approaches the mixed layer, there is net strong transformation toward lighter densities due to mixing of freshwater, but there is a divergence in the density distribution as Upper Circumpolar Deep Water tends become lighter and dense Lower Circumpolar Deep Water tends to become denser. The spatial distribution of transformation shows more rapid transformation at eddy hot spots associated with major topography where density gradients are enhanced; however, the majority of cumulative density change along trajectories is achieved by background mixing. We compare the Lagrangian analysis to diagnosed Eulerian water mass transformation to attribute the mechanisms leading to the observed transformation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3700924','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3700924"><span><span class="hlt">Antarctic</span> Crabs: Invasion or Endurance?</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Griffiths, Huw J.; Whittle, Rowan J.; Roberts, Stephen J.; Belchier, Mark; Linse, Katrin</p> <p>2013-01-01</p> <p>Recent scientific interest following the “discovery” of lithodid crabs around Antarctica has centred on a hypothesis that these crabs might be poised to invade the <span class="hlt">Antarctic</span> shelf if the recent warming trend continues, potentially decimating its native fauna. This “invasion hypothesis” suggests that decapod crabs were driven out of Antarctica 40–15 million years ago and are only now returning as “warm” enough habitats become available. The hypothesis is based on a geographically and spatially poor fossil record of a different group of crabs (Brachyura), and examination of relatively few Recent lithodid samples from the <span class="hlt">Antarctic</span> slope. In this paper, we examine the existing lithodid fossil record and present the distribution and biogeographic patterns derived from over 16,000 records of Recent <span class="hlt">Southern</span> Hemisphere crabs and lobsters. Globally, the lithodid fossil record consists of only two known specimens, neither of which comes from the <span class="hlt">Antarctic</span>. Recent records show that 22 species of crabs and lobsters have been reported from the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, with 12 species found south of 60°S. All are restricted to waters warmer than 0°C, with their <span class="hlt">Antarctic</span> distribution limited to the areas of seafloor dominated by Circumpolar Deep Water (CDW). Currently, CDW extends further and shallower onto the West <span class="hlt">Antarctic</span> shelf than the known distribution ranges of most lithodid species examined. Geological evidence suggests that West <span class="hlt">Antarctic</span> shelf could have been available for colonisation during the last 9,000 years. Distribution patterns, species richness, and levels of endemism all suggest that, rather than becoming extinct and recently re-invading from outside Antarctica, the lithodid crabs have likely persisted, and even radiated, on or near to <span class="hlt">Antarctic</span> slope. We conclude there is no evidence for a modern-day “crab invasion”. We recommend a repeated targeted lithodid sampling program along the West <span class="hlt">Antarctic</span> shelf to fully test the validity of the </p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ESD.....8..323S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ESD.....8..323S"><span>The polar amplification asymmetry: role of <span class="hlt">Antarctic</span> surface height</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Salzmann, Marc</p> <p>2017-05-01</p> <p>Previous studies have attributed an overall weaker (or slower) polar amplification in Antarctica compared to the Arctic to a weaker <span class="hlt">Antarctic</span> surface albedo feedback and also to more efficient <span class="hlt">ocean</span> heat uptake in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in combination with <span class="hlt">Antarctic</span> ozone depletion. Here, the role of the <span class="hlt">Antarctic</span> surface height for meridional heat transport and local radiative feedbacks, including the surface albedo feedback, was investigated based on CO2-doubling experiments in a low-resolution coupled climate model. When Antarctica was assumed to be flat, the north-south asymmetry of the zonal mean top of the atmosphere radiation budget was notably reduced. Doubling CO2 in a flat Antarctica (flat AA) model setup led to a stronger increase in <span class="hlt">southern</span> hemispheric poleward atmospheric and <span class="hlt">oceanic</span> heat transport compared to the base model setup. Based on partial radiative perturbation (PRP) computations, it was shown that local radiative feedbacks and an increase in the CO2 forcing in the deeper atmospheric column also contributed to stronger <span class="hlt">Antarctic</span> warming in the flat AA model setup, and the roles of the individual radiative feedbacks are discussed in some detail. A considerable fraction (between 24 and 80 % for three consecutive 25-year time slices starting in year 51 and ending in year 126 after CO2 doubling) of the polar amplification asymmetry was explained by the difference in surface height, but the fraction was subject to transient changes and might to some extent also depend on model uncertainties. In order to arrive at a more reliable estimate of the role of land height for the observed polar amplification asymmetry, additional studies based on ensemble runs from higher-resolution models and an improved model setup with a more realistic gradual increase in the CO2 concentration are required.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21556153','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21556153"><span>Super-aggregations of krill and humpback whales in Wilhelmina Bay, <span class="hlt">Antarctic</span> Peninsula.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nowacek, Douglas P; Friedlaender, Ari S; Halpin, Patrick N; Hazen, Elliott L; Johnston, David W; Read, Andrew J; Espinasse, Boris; Zhou, Meng; Zhu, Yiwu</p> <p>2011-04-27</p> <p>Ecological relationships of krill and whales have not been explored in the Western <span class="hlt">Antarctic</span> Peninsula (WAP), and have only rarely been studied elsewhere in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. In the austral autumn we observed an extremely high density (5.1 whales per km(2)) of humpback whales (Megaptera novaeangliae) feeding on a super-aggregation of <span class="hlt">Antarctic</span> krill (Euphausia superba) in Wilhelmina Bay. The krill biomass was approximately 2 million tons, distributed over an area of 100 km(2) at densities of up to 2000 individuals m(-3); reports of such 'super-aggregations' of krill have been absent in the scientific literature for >20 years. Retentive circulation patterns in the Bay entrained phytoplankton and meso-zooplankton that were grazed by the krill. Tagged whales rested during daylight hours and fed intensively throughout the night as krill migrated toward the surface. We infer that the previously unstudied WAP embayments are important foraging areas for whales during autumn and, furthermore, that meso-scale variation in the distribution of whales and their prey are important features of this system. Recent decreases in the abundance of <span class="hlt">Antarctic</span> krill around the WAP have been linked to reductions in sea ice, mediated by rapid climate change in this area. At the same time, baleen whale populations in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, which feed primarily on krill, are recovering from past exploitation. Consideration of these features and the effects of climate change on krill dynamics are critical to managing both krill harvests and the recovery of baleen whales in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMGC34A..05P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMGC34A..05P"><span>Simulations of coupled, <span class="hlt">Antarctic</span> ice-<span class="hlt">ocean</span> evolution using POP2x and BISICLES (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Price, S. F.; Asay-Davis, X.; Martin, D. F.; Maltrud, M. E.; Hoffman, M. J.</p> <p>2013-12-01</p> <p>We present initial results from <span class="hlt">Antarctic</span>, ice-<span class="hlt">ocean</span> coupled simulations using large-scale <span class="hlt">ocean</span> circulation and land ice evolution models. The <span class="hlt">ocean</span> model, POP2x is a modified version of POP, a fully eddying, global-scale <span class="hlt">ocean</span> model (Smith and Gent, 2002). POP2x allows for circulation beneath ice shelf cavities using the method of partial top cells (Losch, 2008). Boundary layer physics, which control fresh water and salt exchange at the ice-<span class="hlt">ocean</span> interface, are implemented following Holland and Jenkins (1999), Jenkins (1999), and Jenkins et al. (2010). Standalone POP2x output compares well with standard ice-<span class="hlt">ocean</span> test cases (e.g., ISOMIP; Losch, 2008; Kimura et al., 2013) and with results from other idealized ice-<span class="hlt">ocean</span> coupling test cases (e.g., Goldberg et al., 2012). The land ice model, BISICLES (Cornford et al., 2012), includes a 1st-order accurate momentum balance (L1L2) and uses block structured, adaptive-mesh refinement to more accurately model regions of dynamic complexity, such as ice streams, outlet glaciers, and grounding lines. For idealized test cases focused on marine-ice sheet dynamics, BISICLES output compares very favorably relative to simulations based on the full, nonlinear Stokes momentum balance (MISMIP-3d; Pattyn et al., 2013). Here, we present large-scale (<span class="hlt">southern</span> <span class="hlt">ocean</span>) simulations using POP2x with fixed ice shelf geometries, which are used to obtain and validate modeled submarine melt rates against observations. These melt rates are, in turn, used to force evolution of the BISICLES model. An offline-coupling scheme, which we compare with the ice-<span class="hlt">ocean</span> coupling work of Goldberg et al. (2012), is then used to sequentially update the sub-shelf cavity geometry seen by POP2x.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3835899','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3835899"><span>Humpback Whale Song on the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Feeding Grounds: Implications for Cultural Transmission</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Garland, Ellen C.; Gedamke, Jason; Rekdahl, Melinda L.; Noad, Michael J.; Garrigue, Claire; Gales, Nick</p> <p>2013-01-01</p> <p>Male humpback whales produce a long, complex, and stereotyped song on low-latitude breeding grounds; they also sing while migrating to and from these locations, and occasionally in high-latitude summer feeding areas. All males in a population sing the current version of the constantly evolving display and, within an <span class="hlt">ocean</span> basin, populations sing similar songs; however, this sharing can be complex. In the western and central South Pacific region there is repeated cultural transmission of song types from eastern Australia to other populations eastward. Song sharing is hypothesized to occur through several possible mechanisms. Here, we present the first example of feeding ground song from the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> <span class="hlt">Antarctic</span> Area V and compare it to song from the two closest breeding populations. The early 2010 song contained at least four distinct themes; these matched four themes from the eastern Australian 2009 song, and the same four themes from the New Caledonian 2010 song recorded later in the year. This provides evidence for at least one of the hypothesized mechanisms of song transmission between these two populations, singing while on shared summer feeding grounds. In addition, the feeding grounds may provide a point of acoustic contact to allow the rapid horizontal cultural transmission of song within the western and central South Pacific region and the wider <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. PMID:24278134</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24278134','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24278134"><span>Humpback whale song on the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> feeding grounds: implications for cultural transmission.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Garland, Ellen C; Gedamke, Jason; Rekdahl, Melinda L; Noad, Michael J; Garrigue, Claire; Gales, Nick</p> <p>2013-01-01</p> <p>Male humpback whales produce a long, complex, and stereotyped song on low-latitude breeding grounds; they also sing while migrating to and from these locations, and occasionally in high-latitude summer feeding areas. All males in a population sing the current version of the constantly evolving display and, within an <span class="hlt">ocean</span> basin, populations sing similar songs; however, this sharing can be complex. In the western and central South Pacific region there is repeated cultural transmission of song types from eastern Australia to other populations eastward. Song sharing is hypothesized to occur through several possible mechanisms. Here, we present the first example of feeding ground song from the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> <span class="hlt">Antarctic</span> Area V and compare it to song from the two closest breeding populations. The early 2010 song contained at least four distinct themes; these matched four themes from the eastern Australian 2009 song, and the same four themes from the New Caledonian 2010 song recorded later in the year. This provides evidence for at least one of the hypothesized mechanisms of song transmission between these two populations, singing while on shared summer feeding grounds. In addition, the feeding grounds may provide a point of acoustic contact to allow the rapid horizontal cultural transmission of song within the western and central South Pacific region and the wider <span class="hlt">Southern</span> <span class="hlt">Ocean</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20360985','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20360985"><span>Poles apart: the "bipolar" pteropod species Limacina helicina is genetically distinct between the Arctic and <span class="hlt">Antarctic</span> <span class="hlt">oceans</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hunt, Brian; Strugnell, Jan; Bednarsek, Nina; Linse, Katrin; Nelson, R John; Pakhomov, Evgeny; Seibel, Brad; Steinke, Dirk; Würzberg, Laura</p> <p>2010-03-23</p> <p>The shelled pteropod (sea butterfly) Limacina helicina is currently recognised as a species complex comprising two sub-species and at least five "forma". However, at the species level it is considered to be bipolar, occurring in both the Arctic and <span class="hlt">Antarctic</span> <span class="hlt">oceans</span>. Due to its aragonite shell and polar distribution L. helicina is particularly vulnerable to <span class="hlt">ocean</span> acidification. As a key indicator of the acidification process, and a major component of polar ecosystems, L. helicina has become a focus for acidification research. New observations that taxonomic groups may respond quite differently to acidification prompted us to reassess the taxonomic status of this important species. We found a 33.56% (+/-0.09) difference in cytochrome c oxidase subunit I (COI) gene sequences between L. helicina collected from the Arctic and <span class="hlt">Antarctic</span> <span class="hlt">oceans</span>. This degree of separation is sufficient for ordinal level taxonomic separation in other organisms and provides strong evidence for the Arctic and <span class="hlt">Antarctic</span> populations of L. helicina differing at least at the species level. Recent research has highlighted substantial physiological differences between the poles for another supposedly bipolar pteropod species, Clione limacina. Given the large genetic divergence between Arctic and <span class="hlt">Antarctic</span> L. helicina populations shown here, similarly large physiological differences may exist between the poles for the L. helicina species group. Therefore, in addition to indicating that L. helicina is in fact not bipolar, our study demonstrates the need for acidification research to take into account the possibility that the L. helicina species group may not respond in the same way to <span class="hlt">ocean</span> acidification in Arctic and <span class="hlt">Antarctic</span> ecosystems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSPC14C2083K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSPC14C2083K"><span>Mapping Error in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Transport Computed from Satellite Altimetry and Argo</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kosempa, M.; Chambers, D. P.</p> <p>2016-02-01</p> <p>Argo profiling floats afford basin-scale coverage of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> since 2005. When density estimates from Argo are combined with surface geostrophic currents derived from satellite altimetry, one can estimate integrated geostrophic transport above 2000 dbar [e.g., Kosempa and Chambers, JGR, 2014]. However, the interpolation techniques relied upon to generate mapped data from Argo and altimetry will impart a mapping error. We quantify this mapping error by sampling the high-resolution <span class="hlt">Southern</span> <span class="hlt">Ocean</span> State Estimate (SOSE) at the locations of Argo floats and Jason-1, and -2 altimeter ground tracks, then create gridded products using the same optimal interpolation algorithms used for the Argo/altimetry gridded products. We combine these surface and subsurface grids to compare the sampled-then-interpolated transport grids to those from the original SOSE data in an effort to quantify the uncertainty in volume transport integrated across the <span class="hlt">Antarctic</span> Circumpolar Current (ACC). This uncertainty is then used to answer two fundamental questions: 1) What is the minimum linear trend that can be observed in ACC transport given the present length of the instrument record? 2) How long must the instrument record be to observe a trend with an accuracy of 0.1 Sv/year?</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..1410939S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1410939S"><span>Bioproductivity in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> since the last Interglacial - new high-resolution biogenic opal flux records from the Scotia Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sprenk, D.; Weber, M. E.; Kuhn, G.; Rosén, P.; Röhling, H.-G.</p> <p>2012-04-01</p> <p>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> plays an important role in transferring CO2 via wind-induced upwelling from the deep sea to the atmosphere. It is therefore one of the key areas to study climate change. Bioproductivity in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is mostly influenced by the extent of sea ice, upwelling of cold nutrient- and silica-rich water, and the availability of light. Biogenic opal (BSi) is a significant nutrient in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, and according to recent investigations only marginally affected by preservation changes. It can therefore be used as bioproductivity proxy. Here we present several methods to determine BSi, discuss them and put the results into context with respect to regional bioproductivity changes in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> during the last glacial cycle. We studied deep-sea sediment core sites MD07-3133 and MD07-3134 from the central Scotia Sea with extraordinary high sedimentation rates of up to 2.1 to 1.2 m/kyr, respectively covering the last 92.5 kyr. BSi leaching according to Müller & Schneider (1993) is very time-consuming and expensive, so we measured only 253 samples from large-amplitude variation core sections. In addition, we determined BSi using non-destructive measurements of sediment colour b*, wet-bulk density, and Ti/Si count ratios. Furthermore, we provide the first attempts to estimate BSi in marine sediment using Fourier transform infrared spectroscopy (FTIRS), a cost-efficient method, which requires only 11 mg of sediment. All estimation methods capture the main BSi trends, however FTIRS seems to be the most promising one. In the central Scotia Sea, south of the modern <span class="hlt">Antarctic</span> Polar Front, the BSi flux reflects a relatively complicated glacial-to-interglacial pattern with large-amplitude, millennial-scale fluctuations in bioproductivity. During <span class="hlt">Antarctic</span> Isotopic Maxima, BSi fluxes were generally increased. Lowest bioproductivity occur at the Last Glacial Maximum, while upwelling of mid-depth water was reduced, atmospheric CO2 low, and sea-ice cover</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26359401','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26359401"><span>The reinvigoration of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> carbon sink.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Landschützer, Peter; Gruber, Nicolas; Haumann, F Alexander; Rödenbeck, Christian; Bakker, Dorothee C E; van Heuven, Steven; Hoppema, Mario; Metzl, Nicolas; Sweeney, Colm; Takahashi, Taro; Tilbrook, Bronte; Wanninkhof, Rik</p> <p>2015-09-11</p> <p>Several studies have suggested that the carbon sink in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>-the <span class="hlt">ocean</span>'s strongest region for the uptake of anthropogenic CO2 -has weakened in recent decades. We demonstrated, on the basis of multidecadal analyses of surface <span class="hlt">ocean</span> CO2 observations, that this weakening trend stopped around 2002, and by 2012, the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> had regained its expected strength based on the growth of atmospheric CO2. All three <span class="hlt">Southern</span> <span class="hlt">Ocean</span> sectors have contributed to this reinvigoration of the carbon sink, yet differences in the processes between sectors exist, related to a tendency toward a zonally more asymmetric atmospheric circulation. The large decadal variations in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> carbon sink suggest a rather dynamic <span class="hlt">ocean</span> carbon cycle that varies more in time than previously recognized. Copyright © 2015, American Association for the Advancement of Science.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PrOce.116...31L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PrOce.116...31L"><span>Pteropods and climate off the <span class="hlt">Antarctic</span> Peninsula</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Loeb, Valerie J.; Santora, Jarrod A.</p> <p>2013-09-01</p> <p>Shelled (thecosome) and naked (gymnosome) pteropods are regular, at times abundant, members of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> zooplankton assemblages. Regionally, shelled species can play a major role in food webs and carbon cycling. Because of their aragonite shells thecosome pteropods may be vulnerable to the impacts of <span class="hlt">ocean</span> acidification; without shells they cannot survive and their demise would have major implications for food webs and carbon cycling in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Additionally, pteropod species in the southwest Atlantic sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> inhabit a region of rapid warming and climate change, the impacts of which are predicted to be observed as poleward distribution shifts. Here we provide baseline information on intraseasonal, interannual and longer scale variability of pteropod populations off the <span class="hlt">Antarctic</span> Peninsula between 1994 and 2009. Concentrations of the 4 dominant taxa, Limacina helicina antarctica f. antarctica, Clio pyramidata f. sulcata, Spongiobranchaea australis and Clione limacina antarctica, are similar to those monitored during the 1928-1935 Discovery Investigations and reflect generally low values but with episodic interannual abundance peaks that, except for C. pyr. sulcata, are related to basin-scale climate forcing associated with the El Niño-<span class="hlt">Southern</span> Oscillation (ENSO) climate mode. Significant abundance increases of L. helicina and S. australis after 1998 were associated with a climate regime shift that initiated a period dominated by cool La Niña conditions and increased nearshore influence of the <span class="hlt">Antarctic</span> Circumpolar Current (ACC). This background information is essential to assess potential future changes in pteropod species distribution and abundance associated with <span class="hlt">ocean</span> warming and acidification. construct maps of pteropod spatial frequency and mean abundance to assess their oceanographic associations; quantify pteropod abundance anomalies for comparing intraseasonal and interannual variability relative to m-3 environmental</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3032774','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3032774"><span>Isotopic Investigation of Contemporary and Historic Changes in Penguin Trophic Niches and Carrying Capacity of the <span class="hlt">Southern</span> Indian <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Jaeger, Audrey; Cherel, Yves</p> <p>2011-01-01</p> <p>A temperature-defined regime shift occurred in the 1970s in the <span class="hlt">southern</span> Indian <span class="hlt">Ocean</span>, with simultaneous severe decreases in many predator populations. We tested a possible biological link between the regime shift and predator declines by measuring historic and contemporary feather isotopic signatures of seven penguin species with contrasted foraging strategies and inhabiting a large latitudinal range. We first showed that contemporary penguin isotopic variations and chlorophyll a concentration were positively correlated, suggesting the usefulness of predator δ13C values to track temporal changes in the ecosystem carrying capacity and its associated coupling to consumers. Having controlled for the Suess effect and for increase CO2 in seawater, δ13C values of <span class="hlt">Antarctic</span> penguins and of king penguins did not change over time, while δ13C of other subantarctic and subtropical species were lower in the 1970s. The data therefore suggest a decrease in ecosystem carrying capacity of the <span class="hlt">southern</span> Indian <span class="hlt">Ocean</span> during the temperature regime-shift in subtropical and subantarctic waters but not in the vicinity of the Polar Front and in southward high-<span class="hlt">Antarctic</span> waters. The resulting lower secondary productivity could be the main driving force explaining the decline of subtropical and subantarctic (but not <span class="hlt">Antarctic</span>) penguins that occurred in the 1970s. Feather δ15N values did not show a consistent temporal trend among species, suggesting no major change in penguins’ diet. This study highlights the usefulness of developing long-term tissue sampling and data bases on isotopic signature of key marine organisms to track potential changes in their isotopic niches and in the carrying capacity of the environment. PMID:21311756</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21311756','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21311756"><span>Isotopic investigation of contemporary and historic changes in penguin trophic niches and carrying capacity of the <span class="hlt">southern</span> Indian <span class="hlt">ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jaeger, Audrey; Cherel, Yves</p> <p>2011-02-02</p> <p>A temperature-defined regime shift occurred in the 1970s in the <span class="hlt">southern</span> Indian <span class="hlt">Ocean</span>, with simultaneous severe decreases in many predator populations. We tested a possible biological link between the regime shift and predator declines by measuring historic and contemporary feather isotopic signatures of seven penguin species with contrasted foraging strategies and inhabiting a large latitudinal range. We first showed that contemporary penguin isotopic variations and chlorophyll a concentration were positively correlated, suggesting the usefulness of predator δ¹³C values to track temporal changes in the ecosystem carrying capacity and its associated coupling to consumers. Having controlled for the Suess effect and for increase CO₂ in seawater, δ¹³C values of <span class="hlt">Antarctic</span> penguins and of king penguins did not change over time, while δ¹³C of other subantarctic and subtropical species were lower in the 1970s. The data therefore suggest a decrease in ecosystem carrying capacity of the <span class="hlt">southern</span> Indian <span class="hlt">Ocean</span> during the temperature regime-shift in subtropical and subantarctic waters but not in the vicinity of the Polar Front and in southward high-<span class="hlt">Antarctic</span> waters. The resulting lower secondary productivity could be the main driving force explaining the decline of subtropical and subantarctic (but not <span class="hlt">Antarctic</span>) penguins that occurred in the 1970s. Feather δ¹⁵N values did not show a consistent temporal trend among species, suggesting no major change in penguins' diet. This study highlights the usefulness of developing long-term tissue sampling and data bases on isotopic signature of key marine organisms to track potential changes in their isotopic niches and in the carrying capacity of the environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRC..121.5773S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRC..121.5773S"><span>The effects of <span class="hlt">Antarctic</span> iceberg calving-size distribution in a global climate model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stern, A. A.; Adcroft, A.; Sergienko, O.</p> <p>2016-08-01</p> <p>Icebergs calved from the <span class="hlt">Antarctic</span> continent act as moving sources of freshwater while drifting in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. The lifespan of these icebergs strongly depends on their original size during calving. In order to investigate the effects (if any) of the calving size of icebergs on the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, we use a coupled general circulation model with an iceberg component. Iceberg calving length is varied from 62 m up to 2.3 km, which is the typical range used in climate models. Results show that increasing the size of calving icebergs leads to an increase in the westward iceberg freshwater transport around Antarctica. In simulations using larger icebergs, the reduced availability of meltwater in the Amundsen and Bellingshausen Seas suppresses the sea-ice growth in the region. In contrast, the increased iceberg freshwater transport leads to increased sea-ice growth around much of the East <span class="hlt">Antarctic</span> coastline. These results suggest that the absence of large tabular icebergs with horizontal extent of tens of kilometers in climate models may introduces systematic biases in sea-ice formation, <span class="hlt">ocean</span> temperatures, and salinities around Antarctica.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017OcSci..13..521Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017OcSci..13..521Y"><span>Freshening of <span class="hlt">Antarctic</span> Intermediate Water in the South Atlantic <span class="hlt">Ocean</span> in 2005-2014</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yao, Wenjun; Shi, Jiuxin; Zhao, Xiaolong</p> <p>2017-07-01</p> <p>Basin-scale freshening of <span class="hlt">Antarctic</span> Intermediate Water (AAIW) is reported to have occurred in the South Atlantic <span class="hlt">Ocean</span> during the period from 2005 to 2014, as shown by the gridded monthly means of the Array for Real-time Geostrophic Oceanography (Argo) data. This phenomenon was also revealed by two repeated transects along a section at 30° S, performed during the World <span class="hlt">Ocean</span> Circulation Experiment Hydrographic Program. Freshening of the AAIW was compensated for by a salinity increase of thermocline water, indicating a hydrological cycle intensification. This was supported by the precipitation-minus-evaporation change in the <span class="hlt">Southern</span> Hemisphere from 2000 to 2014. Freshwater input from atmosphere to <span class="hlt">ocean</span> surface increased in the subpolar high-precipitation region and vice versa in the subtropical high-evaporation region. Against the background of hydrological cycle changes, a decrease in the transport of Agulhas Leakage (AL), which was revealed by the simulated velocity field, was proposed to be a contributor to the associated freshening of AAIW. Further calculation showed that such a decrease could account for approximately 53 % of the observed freshening (mean salinity reduction of about 0.012 over the AAIW layer). The estimated variability of AL was inferred from a weakening of wind stress over the South Indian <span class="hlt">Ocean</span> since the beginning of the 2000s, which would facilitate freshwater input from the source region. The mechanical analysis of wind data here was qualitative, but it is contended that this study would be helpful to validate and test predictably coupled sea-air model simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.2341M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.2341M"><span>High storage rates of anthropogenic CO_{2} in the Indian sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Murata, Akihiko; Kumamoto, Yu-ichiro; Sasaki, Ken-ichi</p> <p>2017-04-01</p> <p>Using high-quality data for CO2-system and related properties collected 17 years apart through international observation programs, we examined decadal-scale increases of anthropogenic CO2 along a zonal section at nominal 62˚ S ranging from 30˚ E to 160˚ E in the Indian sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. In contrast to previous studies, increases of anthropogenic CO2 were largest (> 9.0 μmol kg-1) in <span class="hlt">Antarctic</span> Bottom Water, where little storage of anthropogenic CO2 has been reported. Significant increases of anthropogenic CO2 in bottom and/or deep waters were detected through the section, although they became reduced in magnitude and depth range west of 110˚ E. Vertical distributions of anthropogenic CO2 showed significant positive correlations with decadal-scale changes in CFC-12, a proxy of circulation and ventilation, meaning that the distributions were mainly controlled by physical processes. Comparison of increases of anthropogenic CO2 between calculation methods with and without total alkalinity presented differences of increases of anthropogenic CO2west of 50˚ E. This is probably because decreases in production of particulate inorganic carbons in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. The highest storage rate of anthropogenic CO2 was estimated to be 1.1 ± 0.6 mol m-2 a-1 at longitudes 130˚ -160˚ E. The results highlight storage rates higher than ever reported in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, where very low storage of anthropogenic CO2 has been evidenced.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930044322&hterms=stress+relationship&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dstress%2Brelationship','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930044322&hterms=stress+relationship&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dstress%2Brelationship"><span>Coastal zone color scanner pigment concentrations in the <span class="hlt">southern</span> <span class="hlt">ocean</span> and relationships to geophysical surface features</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Comiso, J. C.; Mcclain, C. R.; Sullivan, C. W.; Ryan, J. P.; Leonard, C. L.</p> <p>1993-01-01</p> <p>Climatological data on the distribution of surface pigment fields in the entire <span class="hlt">southern</span> <span class="hlt">ocean</span> over a seasonal cycle are examined. The occurrence of intense phytoplankton blooms during austral summer months and during other seasons in different regions is identified and analyzed. The highest pigment concentrations are observed at high latitudes and over regions with water depths usually less than 600 m. Basin-scale pigment distribution shows a slightly asymmetric pattern of enhanced pigment concentrations about Antarctica, with enhanced concentrations extending to lower latitudes in the Atlantic and Indian sectors than in the Pacific sector. A general increase in pigment concentrations is evident from the low latitudes toward the <span class="hlt">Antarctic</span> circumpolar region. Spatial relationships between pigment and archived geophysical data reveal significant correlation between pigment distributions and both bathymetry and wind stress, while general hemispheric scale patterns of pigment distributions are most coherent with the geostrophic flow of the <span class="hlt">Antarctic</span> Circumpolar Current.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMPP43B1353H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMPP43B1353H"><span>Centennial-Scale Relationship Between the <span class="hlt">Southern</span> Hemisphere Westerly Winds and Temperature</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hodgson, D. A.; Perren, B.; Roberts, S. J.; Sime, L. C.; Verleyen, E.; Van Nieuwenhuyze, W.; Vyverman, W.</p> <p>2017-12-01</p> <p>Recent changes in the intensity and position of the <span class="hlt">Southern</span> Hemisphere Westerly Winds (SHW) have been implicated in a number of important physical changes in the <span class="hlt">Southern</span> High Latitudes. These include changes in the efficiency of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> CO2 sink through alterations in <span class="hlt">ocean</span> circulation, the loss of <span class="hlt">Antarctic</span> ice shelves through enhanced basal melting, changes in <span class="hlt">Antarctic</span> sea ice extent, and warming of the <span class="hlt">Antarctic</span> Peninsula. Many of these changes have far-reaching implications for global climate and sea level rise. Despite the importance of the SHW in global climate, our current understanding of the past and future behaviour of the westerly winds is limited by relatively few reconstructions and measurements of the SHW in their core belt over the <span class="hlt">Antarctic</span> Circumpolar Current; the region most relevant to <span class="hlt">Southern</span> <span class="hlt">Ocean</span> air-sea gas exchange. The aim of this study was to reconstruct changes in the relative strength of the SHW at Marion Island, one of a small number of sub-<span class="hlt">Antarctic</span> islands that lie in the core of the SHWs. We applied independent diatom- and geochemistry- based methods to track past changes in relative wind intensity. This mutiproxy approach provides a validation that the proxies are responding to the external forcing (the SHW) rather than local (e.g. precipitation ) or internal dynamics. Results show that that the strength of the SHW are intrinsically linked to extratropical temperatures over centennial timescales, with warmer temperatures driving stronger winds. Our findings also suggest that large variations in the path and intensity of the westerly winds are driven by relatively small variations in temperature over these timescales. This means that with continued climate warming, even in the absence of anthropogenic ozone-depletion, we should anticipate large shifts in the SHW, causing stronger, more poleward-intensified winds in the decades and centuries to come, with attendant impacts on <span class="hlt">ocean</span> circulation, ice shelf stability, and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015OcDyn..65..751C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015OcDyn..65..751C"><span>Why is there net surface heating over the <span class="hlt">Antarctic</span> Circumpolar Current?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Czaja, Arnaud; Marshall, John</p> <p>2015-05-01</p> <p>Using a combination of atmospheric reanalysis data, climate model outputs and a simple model, key mechanisms controlling net surface heating over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> are identified. All data sources used suggest that, in a streamline-averaged view, net surface heating over the <span class="hlt">Antarctic</span> Circumpolar Current (ACC) is a result of net accumulation of solar radiation rather than a result of heat gain through turbulent fluxes (the latter systematically cool the upper <span class="hlt">ocean</span>). It is proposed that the fraction of this net radiative heat gain realized as net ACC heating is set by two factors. First, the sea surface temperature at the <span class="hlt">southern</span> edge of the ACC. Second, the relative strength of the negative heatflux feedbacks associated with evaporation at the sea surface and advection of heat by the residual flow in the <span class="hlt">oceanic</span> mixed layer. A large advective feedback and a weak evaporative feedback maximize net ACC heating. It is shown that the present <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and its circumpolar current are in this heating regime.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSPC14D2094R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSPC14D2094R"><span>Impact of Parameterized Lateral Mixing on the Circulation of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ragen, S.; Gnanadesikan, A.</p> <p>2016-02-01</p> <p>The <span class="hlt">Antarctic</span> Circumpolar Current (ACC) is the strongest <span class="hlt">ocean</span> current in the world, transporting approximately 130 Sv Eastward around Antarctica. This current is often poorly simulated in climate models. It is not clear why this is the case as the Circumpolar Current is affected by both wind and buoyancy. Changes in wind and buoyancy are not independent of each other, however, so determining the effects of both separately has proved difficult. This study was undertaken in order to examine the impact of changing the lateral diffusion coefficient A­redi on ACC transport. A­redi is poorly known and its value ranges across an order of magnitude in the current generation of climate models. To explore these dynamics, a coarse resolution, fully coupled model suite was run with A­redi mixing coefficients of 400 m2/s, 800 m2/s, 1200 m2/s, and 2400 m2/s. Additionally, two models were run with two-dimensional representations of the mixing coefficient based on altimetry. Our initial results indicate that higher values of the lateral mixing coefficient result in the following changes. We see weaker winds over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> as a whole. The high mixing case results in an 8.7% decrease in peak wind stress. We see a 2% weaker transport in the Drake Passage in the highest mixing case compared to the lowest, but an 11% decrease in transport for a zonal average. The change of temperature and salinity with depth with different Redi parameters also shows a significant difference between the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> as a whole and the Drake Passage. Our findings seem to suggest that the Drake Passage is not an adequate diagnostic for explaining the differences between different climate models, as processes distant from the passage may play an important role. Observed changes in overturning with an increase in lateral mixing include an increase in northward transport of <span class="hlt">Antarctic</span> Bottom Water fed by a small diversion of northern deep water inflows. This diversion means that less of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28187682','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28187682"><span>Polychaeta Orbiniidae from Antarctica, the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, the Abyssal Pacific <span class="hlt">Ocean</span>, and off South America.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Blake, James A</p> <p>2017-01-12</p> <p>The orbiniid polychaetes chiefly from <span class="hlt">Antarctic</span> and subantarctic seas and off South America are described based on collections of the National Museum of Natural History and new material from surveys conducted by the United States <span class="hlt">Antarctic</span> Program and other federal and privately funded sources as well as participation in international programs. A total of 44 species of Orbiniidae distributed in 10 genera are reported from the Pacific <span class="hlt">Ocean</span> and waters off South America and Antarctica. Twenty-one species are new to science; one species is renamed. Berkeleyia heroae n. sp., B. abyssala n. sp., B. weddellia n. sp.; B. hadala n. sp., Leitoscoloplos simplex n. sp., L. plataensis n. sp., L. nasus n. sp., L. eltaninae n. sp., L. phyllobranchus n. sp., L. rankini n. sp., Scoloplos bathytatus n. sp., S. suroestense n. sp., Leodamas hyphalos n. sp., L. maciolekae n. sp., L. perissobranchiatus n. sp., Califia bilamellata n. sp., Orbinia orensanzi n. sp., Naineris antarctica n. sp., N. argentiniensis n. sp., Orbiniella spinosa n. sp., and O. landrumae n. sp. are new to science. A new name, Naineris furcillata, replaces N. chilensis Carrasco, 1977, a junior homonym of N. dendtritica chilensis Hartmann‑Schröder, 1965, which is raised to full species status. Leodamas cochleatus (Ehlers, 1900) is removed from synonymy and redescribed. A neotype is established for Leodamas verax Kinberg, 1966, the type species. A general overview of Leodamas species is provided. The Leitoscoloplos kerguelensis (McIntosh, 1885) complex is reviewed and partially revised. Definitions of the genera of the Orbiniidae are updated to conform to recently described taxa. Several new synonymies are proposed following a reexamination of previously described type specimens. The morphological characters used to identify and classify orbiniids are reviewed. The biogeographic and bathymetric distributions of the South American and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> orbiniid fauna are reviewed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23770316','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23770316"><span>Organophosphorus esters in the <span class="hlt">oceans</span> and possible relation with <span class="hlt">ocean</span> gyres.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cheng, Wenhan; Xie, Zhouqing; Blais, Jules M; Zhang, Pengfei; Li, Ming; Yang, Chengyun; Huang, Wen; Ding, Rui; Sun, Liguang</p> <p>2013-09-01</p> <p>Four organophosphorus esters (OPEs) were detected in aerosol samples collected in the West Pacific, the Indian <span class="hlt">Ocean</span> and the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> from 2009 to 2010, suggesting their circumpolar and global distribution. In general, the highest concentrations were detected near populated regions in China, Australia and New Zealand. OPE concentrations in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> were about two orders of magnitude lower than those near major continents. Additionally, relatively high OPE concentrations were detected at the <span class="hlt">Antarctic</span> Peninsula, where several scientific survey stations are located. The four OPEs investigated here are significantly correlated with each other, suggesting they may derive from the same source. In the circumpolar transect, OPE concentrations were associated with <span class="hlt">ocean</span> gyres in the open <span class="hlt">ocean</span>. Their concentrations were positively related with average vorticity in the sampling area suggesting that a major source of OPEs may be found in <span class="hlt">ocean</span> gyres where plastic debris is known to accumulate. Copyright © 2013 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28441600','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28441600"><span>Microplastics in the <span class="hlt">Antarctic</span> marine system: An emerging area of research.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Waller, Catherine L; Griffiths, Huw J; Waluda, Claire M; Thorpe, Sally E; Loaiza, Iván; Moreno, Bernabé; Pacherres, Cesar O; Hughes, Kevin A</p> <p>2017-11-15</p> <p>It was thought that the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> was relatively free of microplastic contamination; however, recent studies and citizen science projects in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> have reported microplastics in deep-sea sediments and surface waters. Here we reviewed available information on microplastics (including macroplastics as a source of microplastics) in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. We estimated primary microplastic concentrations from personal care products and laundry, and identified potential sources and routes of transmission into the region. Estimates showed the levels of microplastic pollution released into the region from ships and scientific research stations were likely to be negligible at the scale of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, but may be significant on a local scale. This was demonstrated by the detection of the first microplastics in shallow benthic sediments close to a number of research stations on King George Island. Furthermore, our predictions of primary microplastic concentrations from local sources were five orders of magnitude lower than levels reported in published sampling surveys (assuming an even dispersal at the <span class="hlt">ocean</span> surface). Sea surface transfer from lower latitudes may contribute, at an as yet unknown level, to <span class="hlt">Southern</span> <span class="hlt">Ocean</span> plastic concentrations. Acknowledging the lack of data describing microplastic origins, concentrations, distribution and impacts in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, we highlight the urgent need for research, and call for routine, standardised monitoring in the <span class="hlt">Antarctic</span> marine system. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GPC...163...18B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GPC...163...18B"><span>Multiple states in the late Eocene <span class="hlt">ocean</span> circulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baatsen, M. L. J.; von der Heydt, A. S.; Kliphuis, M.; Viebahn, J.; Dijkstra, H. A.</p> <p>2018-04-01</p> <p>The Eocene-Oligocene Transition (EOT) marks a major step within the Cenozoic climate in going from a greenhouse into an icehouse state, with the formation of a continental-scale <span class="hlt">Antarctic</span> ice sheet. The roles of steadily decreasing CO2 concentrations versus changes in <span class="hlt">ocean</span> circulation at the EOT are still debated and the threshold for <span class="hlt">Antarctic</span> glaciation is obscured by uncertainties in global geometry. Here, a detailed study of the late Eocene <span class="hlt">ocean</span> circulation is carried out using an <span class="hlt">ocean</span> general circulation model under two slightly different geography reconstructions of the middle-to-late Eocene (38 Ma). Using the same atmospheric forcing, both geographies give a profoundly different equilibrium <span class="hlt">ocean</span> circulation state. The underlying reason for this sensitivity is the presence of multiple equilibria characterised by either North or South Pacific deep water formation. A possible shift from a <span class="hlt">southern</span> towards a northern overturning circulation would result in significant changes in the global heat distribution and consequently make the <span class="hlt">Southern</span> Hemisphere climate more susceptible for significant cooling and ice sheet formation on Antarctica.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoRL..43.3822M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoRL..43.3822M"><span>Rapid variability of <span class="hlt">Antarctic</span> Bottom Water transport into the Pacific <span class="hlt">Ocean</span> inferred from GRACE</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mazloff, Matthew R.; Boening, Carmen</p> <p>2016-04-01</p> <p>Air-ice-<span class="hlt">ocean</span> interactions in the <span class="hlt">Antarctic</span> lead to formation of the densest waters on Earth. These waters convect and spread to fill the global abyssal <span class="hlt">oceans</span>. The heat and carbon storage capacity of these water masses, combined with their abyssal residence times that often exceed centuries, makes this circulation pathway the most efficient sequestering mechanism on Earth. Yet monitoring this pathway has proven challenging due to the nature of the formation processes and the depth of the circulation. The Gravity Recovery and Climate Experiment (GRACE) gravity mission is providing a time series of <span class="hlt">ocean</span> mass redistribution and offers a transformative view of the abyssal circulation. Here we use the GRACE measurements to infer, for the first time, a 2003-2014 time series of <span class="hlt">Antarctic</span> Bottom Water export into the South Pacific. We find this export highly variable, with a standard deviation of 1.87 sverdrup (Sv) and a decorrelation timescale of less than 1 month. A significant trend is undetectable.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMPP53D..04H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMPP53D..04H"><span>A Deep-Sea Coral Clumped Isotope Record From <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Intermediate Water Spanning the Most Recent Glacial Termination</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hines, S.; Eiler, J. M.; Adkins, J. F.</p> <p>2015-12-01</p> <p>Movement of intermediate waters plays an important role in global heat and carbon transport in the <span class="hlt">ocean</span> and changes in their distribution are closely tied to glacial-interglacial climate change. <span class="hlt">Ocean</span> temperature is necessarily linked to circulation because density is a function of temperature and salinity. In the modern <span class="hlt">ocean</span>, stratification is dominated by differences in temperature, but this may not have been the case in the past. Coupled radiocarbon and U/Th dates on deep-sea Desmophyllum dianthus corals allow for the reconstruction of past intermediate water circulation rates. The addition of temperature measurements further aids in understanding of the mechanisms driving the observed signals, since there are different boundary conditions for resetting these two properties at the surface. In the modern <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, temperature and radiocarbon are broadly correlated. At the surface there are meridional gradients of these properties, with colder, more radiocarbon-depleted water closer to the <span class="hlt">Antarctic</span> continent. We present a high-resolution time series of clumped isotope temperature measurements on 30 corals spanning the Last Glacial Maximum through the end of the <span class="hlt">Antarctic</span> Cold Reversal (ACR). These samples have previously been U/Th and radiocarbon dated. Corals were collected south of Tasmania from depths of between ~1450 - 1900 m, with 70% between 1500 and 1700 m. Uranium and thorium measurements were made by MC-ICP-MS on a ThermoFinnigan Neptune, radiocarbon was measured by AMS at the KCCAMS Laboratory at UC Irvine, and clumped isotope temperatures were measured on a MAT 253 attached to an automated carbonate preparation line. Preliminary results show constant temperature between ~20 - 18 ka, a gradual rise of ~6 ºC through Heinrich Stadial 1 (~18 - 15 ka), an abrupt drop of ~7 ºC directly preceeding the start of the Bølling at 14.7 ka, and another slight rise of ~4 ºC through the ACR (14.7 - 12.8 ka). The addition of clumped isotope temperatures to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002DSRII..49.1623S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002DSRII..49.1623S"><span>Carbon export fluxes in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>: results from inverse modeling and comparison with satellite-based estimates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schlitzer, Reiner</p> <p></p> <p>The use of dissolved nutrients and carbon for photosynthesis in the euphotic zone and the subsequent downward transport of particulate and dissolved organic material strongly affect carbon concentrations in surface water and thus the air-sea exchange of CO 2. Efforts to quantify the downward carbon flux for the whole <span class="hlt">ocean</span> or on basin-scales are hampered by the sparseness of direct productivity or flux measurements. Here, a global <span class="hlt">ocean</span> circulation, biogeochemical model is used to determine rates of export production and vertical carbon fluxes in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. The model exploits the existing large sets of hydrographic, oxygen, nutrient and carbon data that contain information on the underlying biogeochemical processes. The model is fitted to the data by systematically varying circulation, air-sea fluxes, production, and remineralization rates simultaneously. Use of the adjoint method yields model property simulations that are in very good agreement with measurements. In the model, the total integrated export flux of particulate organic matter necessary for the realistic reproduction of nutrient data is significantly larger than export estimates derived from primary productivity maps. Of the 10,000 TgC yr -1(10 GtC yr -1) required globally, the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> south of 30°S contributes about 3000 TgC yr -1 (33%), most of it occurring in a zonal belt along the <span class="hlt">Antarctic</span> Circumpolar Current and in the Peru, Chile and Namibia coastal upwelling regions. The export flux of POC for the area south of 50°S amounts to 1000±210 TgC yr -1, and the particle flux in 1000 m for the same area is 115±20 TgC yr -1. Unlike for the global <span class="hlt">ocean</span>, the contribution of the downward flux of dissolved organic carbon is significant in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in the top 500 m of the water column. Comparison with satellite-based productivity estimates (CZCS and SeaWiFS) shows a relatively good agreement over most of the <span class="hlt">ocean</span> except for the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> south of 50°S, where the model</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015DokES.464.1033N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015DokES.464.1033N"><span>Influence of frontal zones on the distribution of particulate matter and organic compounds in surface waters of the Atlantic and <span class="hlt">Southern</span> <span class="hlt">Oceans</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nemirovskaya, I. A.; Lisitzin, A. P.; Kravchishina, M. D.; Redzhepova, Z. Yu.</p> <p>2015-10-01</p> <p>Particulate matter and organic compounds (chlorophyll, lipids, and hydrocarbons) were analyzed in surface waters along the routes of R/Vs Akademik Fedorov (cruise 32) and Akademik Treshnikov (cruise 2) in February-May of 2012 and 2014, respectively, in the course of the 57th and 59th Russian <span class="hlt">Antarctic</span> expeditions. It was found that the frontal zones exert the primary influence on the concentrations of the mentioned components in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and in the western part of the Atlantic <span class="hlt">Ocean</span>. The supply of pollutants into the Eastern Atlantic <span class="hlt">Ocean</span> on the shelf of the Iberian peninsula results in a pronounced increase in the concentrations of lipids and hydrocarbons causing local anthropogenic pollution zones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-GSFC_20171208_Archive_e000750.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-GSFC_20171208_Archive_e000750.html"><span>Eddies in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2015-04-08</p> <p>The cloud cover over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> occasionally parts as it did on January 1, 2015 just west of the Drake Passage where the VIIRS instrument on the Suomi NPP satellite glimpsed the above collection of <span class="hlt">ocean</span>-color delineated eddies which have diameters ranging from a couple of kilometers to a couple of hundred kilometers. Recent studies indicate that eddy activity has been increasing in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> with possible implications for climate change. Credit: NASA's <span class="hlt">Ocean</span>Color/Suomi NPP/VIIRS NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMPP51E..07M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMPP51E..07M"><span>The Nature of <span class="hlt">Antarctic</span> Temperature Change</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Markle, B. R.; Steig, E. J.</p> <p>2017-12-01</p> <p>The <span class="hlt">Antarctic</span> is an important component of global climate. While the Arctic has warmed significantly in the last century, the <span class="hlt">Antarctic</span> as a whole has shown considerably less variability. There is, however, a pronounced spatial pattern to modern <span class="hlt">Antarctic</span> temperature change. The high East <span class="hlt">Antarctic</span> Ice Sheet shows little to no warming over recent decades while West Antarctica and the Peninsula shows some of the largest rates of warming on the globe. Examining past climate variability can help reveal the physical processes governing this spatial pattern of <span class="hlt">Antarctic</span> temperature change. Modern <span class="hlt">Antarctic</span> temperature variability is known from satellite and weather station observations. Understanding changes in the past, however, requires paleoclimate-proxies such as ice-core water-isotope records. Here we assess the spatial pattern of <span class="hlt">Antarctic</span> temperature changes across a range of timescales, from modern decadal changes to millennial and orbital-scale variability. We reconstruct past changes in absolute temperatures from a suite of deep ice core records and an improved isotope-temperature reconstruction method. We use δ18O and deuterium excess records to reconstruct both evaporation source and condensation site temperatures. In contrast to previous studies we use a novel method that accounts for nonlinearities in the water-isotope distillation process. We quantify past temperature changes over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and <span class="hlt">Antarctic</span> Continent and the magnitude of polar amplification. We identify patterns of <span class="hlt">Antarctic</span> temperature change that are common across a wide range of timescales and independent of the source of forcing. We examine the nature of these changes and their relationship to atmospheric thermodynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004ESRv...66..143B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004ESRv...66..143B"><span>Origin, signature and palaeoclimatic influence of the <span class="hlt">Antarctic</span> Circumpolar Current</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barker, P. F.; Thomas, E.</p> <p>2004-06-01</p> <p>The <span class="hlt">Antarctic</span> Circumpolar Current (ACC) is today the strongest current in the world's <span class="hlt">ocean</span>, with a significant influence on global climate. Its assumed history and influence on palaeoclimate, while almost certainly equally profound, are here called into question. In this paper, we review 30 years of accumulated data, interpretation and speculation about the ACC, deriving mainly from DSDP and ODP drilling in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. For most of this time, a conventional view of ACC development, signature and influence has held sway among palaeoceanographers and marine geologists. In this view, the ACC began at about 34 Ma, close to the Eocene-Oligocene boundary, the time of onset of significant <span class="hlt">Antarctic</span> glaciation and the time of creation of a deep-water gap (Tasmanian Seaway) between Australia and Antarctica as the South Tasman Rise separated from North Victoria Land. This is the "smoking gun" of synchroneity. The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> sediment record shows a latest Eocene development and subsequent geographic expansion of a siliceous biofacies, its northern limit taken to indicate the palaeo-position of the ACC axis. In addition, the ACC was considered to have caused <span class="hlt">Antarctic</span> glaciation by isolating the continent within a cold-water annulus, reducing north-south heat transport. A different (and later) date for <span class="hlt">Antarctic</span>-South American opening ("Drake Passage") was proposed, but the timing of ACC onset there was disputed, and the simple story survived. Recent developments, however, call it into question. Modern physical oceanography shows that all or most of present-day ACC transport is confined to narrow jets within deep-reaching circumpolar fronts, and numerical modelling has suggested that a steady reduction in greenhouse gas concentration through the Cenozoic could cause <span class="hlt">Antarctic</span> glaciation, with or without a contribution from <span class="hlt">ocean</span> circulation change. The rapidity of <span class="hlt">Antarctic</span> glacial onset at the Eocene-Oligocene boundary and coeval creation of a deep-water gap south</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMPP41E..08T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMPP41E..08T"><span>140-year subantarctic tree-ring temperature reconstruction reveals tropical forcing of increased <span class="hlt">Southern</span> <span class="hlt">Ocean</span> climate variability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Turney, C. S.; Fogwill, C. J.; Palmer, J. G.; VanSebille, E.; Thomas, Z.; McGlone, M.; Richardson, S.; Wilmshurst, J.; Fenwick, P.; Zunz, V.; Goosse, H.; Wilson, K. J.; Carter, L.; Lipson, M.; Jones, R. T.; Harsch, M.; Clark, G.; Marzinelli, E.; Rogers, T.; Rainsley, E.; Ciasto, L.; Waterman, S.; Thomas, E. R.; Visbeck, M.</p> <p>2017-12-01</p> <p>Occupying about 14 % of the world's surface, the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> plays a fundamental role in <span class="hlt">ocean</span> and atmosphere circulation, carbon cycling and <span class="hlt">Antarctic</span> ice-sheet dynamics. Unfortunately, high interannual variability and a dearth of instrumental observations before the 1950s limits our understanding of how marine-atmosphere-ice domains interact on multi-decadal timescales and the impact of anthropogenic forcing. Here we integrate climate-sensitive tree growth with <span class="hlt">ocean</span> and atmospheric observations on south-west Pacific subantarctic islands that lie at the boundary of polar and subtropical climates (52-54˚S). Our annually resolved temperature reconstruction captures regional change since the 1870s and demonstrates a significant increase in variability from the 1940s, a phenomenon predating the observational record, and coincident with major changes in mammalian and bird populations. Climate reanalysis and modelling show a parallel change in tropical Pacific sea surface temperatures that generate an atmospheric Rossby wave train which propagates across a large part of the <span class="hlt">Southern</span> Hemisphere during the austral spring and summer. Our results suggest that modern observed high interannual variability was established across the mid-twentieth century, and that the influence of contemporary equatorial Pacific temperatures may now be a permanent feature across the mid- to high latitudes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.T31C0636P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.T31C0636P"><span>Geophysical Investigation of Upper Mantle Anomalies of the Australian-<span class="hlt">Antarctic</span> Ridge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Park, S. H.; Choi, H.; Kim, S. S.; Lin, J.</p> <p>2017-12-01</p> <p>Australian-<span class="hlt">Antarctic</span> Ridge (AAR) is situated between the Pacific-<span class="hlt">Antarctic</span> Ridge (PAR) and Southeast Indian Ridge (SEIR), extending eastward from the Australian-<span class="hlt">Antarctic</span> Discordance (AAD). Much of the AAR has been remained uncharted until 2011 because of its remoteness and harsh weather conditions. Since 2011, four multidisciplinary expeditions initiated by the Korea Polar Research Institute (KOPRI) have surveyed the little-explored eastern ends of the AAR and investigated the tectonics, geochemistry, and hydrothermal activity of this intermediate spreading system. Recent isotope studies using the new basalt samples from the AAR have led to the new hypothesis of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> mantle domain (SOM), which may have originated from the super-plume activity associated with the Gondwana break-up. In this study, we characterize the geophysics of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> mantle using the newly acquired shipboard bathymetry and available geophysical datasets. First, we computed residual mantle Bouguer gravity anomalies (RMBA), gravity-derived crustal thickness, and residual topography along the AAR in order to obtain a geological proxy for regional variations in magma supply. The results of these analyses revealed that the <span class="hlt">southern</span> flank of the AAR is associated with shallower seafloor, more negative RMBA, thicker crust, and/or less dense mantle in comparison to the conjugate northern flank. Furthermore, this north-south asymmetry becomes more prominent toward the central ridge segments of the AAR. Interestingly, the along-axis depths of the entire AAR are significantly shallower than the neighboring ridge systems and the global ridges of intermediate spreading rates. Such shallow depths are also correlated with regional negative geoid anomalies. Furthermore, recent mantle tomography models consistently showed that the upper mantle (< 250 km) below the AAR has low S-wave velocities, suggesting that it may be hotter than the nearby ridges. Such regional-scale anomalies of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMOS41F..08N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMOS41F..08N"><span>A Microscale View of Mixing and Overturning Across the <span class="hlt">Antarctic</span> Circumpolar Current</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Naveira Garabato, A.; Polzin, K. L.; Ferrari, R. M.; Zika, J. D.; Forryan, A.</p> <p>2014-12-01</p> <p>The meridional overturning circulation and stratication of the global <span class="hlt">ocean</span> are shaped critically by processes in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. The zonally unblocked nature of the <span class="hlt">Antarctic</span> Circumpolar Current (ACC) confers the region with a set of special dynamics that ultimately results in the focussing therein of large vertical exchanges between layers spanning the global <span class="hlt">ocean</span> pycnocline. These vertical exchanges are thought to be mediated by <span class="hlt">oceanic</span> turbulent motions (associated with mesoscale eddies and small-scale turbulence), yet the vastness of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and the sparse and intermittent nature of turbulent processes make their relative roles and large-scale impacts extremely difficult to assess.Here, we address the problem from a new angle, and use measurements of the centimetre-scale signatures of mesoscale eddies and small-scale turbulence obtained during the DIMES experiment to determine the contributions of those processes to sustaining large-scale meridional overturning across the ACC. We find that mesoscale eddies and small-scale turbulence play complementary roles in forcing a meridional circulation of O(1 mm / s) across the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, and that their roles are underpinned by distinct and abrupt variations in the rates at which they mix water parcels. The implications for our understanding of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> circulation's sensitivity to climatic change will be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28970064','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28970064"><span>Cross-disciplinarity in the advance of <span class="hlt">Antarctic</span> ecosystem research.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gutt, J; Isla, E; Bertler, A N; Bodeker, G E; Bracegirdle, T J; Cavanagh, R D; Comiso, J C; Convey, P; Cummings, V; De Conto, R; De Master, D; di Prisco, G; d'Ovidio, F; Griffiths, H J; Khan, A L; López-Martínez, J; Murray, A E; Nielsen, U N; Ott, S; Post, A; Ropert-Coudert, Y; Saucède, T; Scherer, R; Schiaparelli, S; Schloss, I R; Smith, C R; Stefels, J; Stevens, C; Strugnell, J M; Trimborn, S; Verde, C; Verleyen, E; Wall, D H; Wilson, N G; Xavier, J C</p> <p>2018-02-01</p> <p>The biodiversity, ecosystem services and climate variability of the <span class="hlt">Antarctic</span> continent and the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> are major components of the whole Earth system. <span class="hlt">Antarctic</span> ecosystems are driven more strongly by the physical environment than many other marine and terrestrial ecosystems. As a consequence, to understand ecological functioning, cross-disciplinary studies are especially important in <span class="hlt">Antarctic</span> research. The conceptual study presented here is based on a workshop initiated by the Research Programme <span class="hlt">Antarctic</span> Thresholds - Ecosystem Resilience and Adaptation of the Scientific Committee on <span class="hlt">Antarctic</span> Research, which focussed on challenges in identifying and applying cross-disciplinary approaches in the <span class="hlt">Antarctic</span>. Novel ideas and first steps in their implementation were clustered into eight themes. These ranged from scale problems, through risk maps, and organism/ecosystem responses to multiple environmental changes and evolutionary processes. Scaling models and data across different spatial and temporal scales were identified as an overarching challenge. Approaches to bridge gaps in <span class="hlt">Antarctic</span> research programmes included multi-disciplinary monitoring, linking biomolecular findings and simulated physical environments, as well as integrative ecological modelling. The results of advanced cross-disciplinary approaches can contribute significantly to our knowledge of <span class="hlt">Antarctic</span> and global ecosystem functioning, the consequences of climate change, and to global assessments that ultimately benefit humankind. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2847597','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2847597"><span>Poles Apart: The “Bipolar” Pteropod Species Limacina helicina Is Genetically Distinct Between the Arctic and <span class="hlt">Antarctic</span> <span class="hlt">Oceans</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bednarsek, Nina; Linse, Katrin; Nelson, R. John; Pakhomov, Evgeny; Seibel, Brad; Steinke, Dirk; Würzberg, Laura</p> <p>2010-01-01</p> <p>The shelled pteropod (sea butterfly) Limacina helicina is currently recognised as a species complex comprising two sub-species and at least five “forma”. However, at the species level it is considered to be bipolar, occurring in both the Arctic and <span class="hlt">Antarctic</span> <span class="hlt">oceans</span>. Due to its aragonite shell and polar distribution L. helicina is particularly vulnerable to <span class="hlt">ocean</span> acidification. As a key indicator of the acidification process, and a major component of polar ecosystems, L. helicina has become a focus for acidification research. New observations that taxonomic groups may respond quite differently to acidification prompted us to reassess the taxonomic status of this important species. We found a 33.56% (±0.09) difference in cytochrome c oxidase subunit I (COI) gene sequences between L. helicina collected from the Arctic and <span class="hlt">Antarctic</span> <span class="hlt">oceans</span>. This degree of separation is sufficient for ordinal level taxonomic separation in other organisms and provides strong evidence for the Arctic and <span class="hlt">Antarctic</span> populations of L. helicina differing at least at the species level. Recent research has highlighted substantial physiological differences between the poles for another supposedly bipolar pteropod species, Clione limacina. Given the large genetic divergence between Arctic and <span class="hlt">Antarctic</span> L. helicina populations shown here, similarly large physiological differences may exist between the poles for the L. helicina species group. Therefore, in addition to indicating that L. helicina is in fact not bipolar, our study demonstrates the need for acidification research to take into account the possibility that the L. helicina species group may not respond in the same way to <span class="hlt">ocean</span> acidification in Arctic and <span class="hlt">Antarctic</span> ecosystems. PMID:20360985</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMPP11B1792Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMPP11B1792Z"><span>Pleistocene atmospheric CO2 change linked to <span class="hlt">Southern</span> <span class="hlt">Ocean</span> nutrient utilization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ziegler, M.; Diz, P.; Hall, I. R.; Zahn, R.</p> <p>2011-12-01</p> <p>Biological uptake of CO2 by the <span class="hlt">ocean</span> and its subsequent storage in the abyss is intimately linked with the global carbon cycle and constitutes a significant climatic force1. The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is a particularly important region because its wind-driven upwelling regime brings CO2 laden abyssal waters to the surface that exchange CO2 with the atmosphere. The Subantarctic Zone (SAZ) is a CO2 sink and also drives global primary productivity as unutilized nutrients, advected with surface waters from the south, are exported via Subantarctic Mode Water (SAMW) as preformed nutrients to the low latitudes where they fuel the biological pump in upwelling areas. Recent model estimates suggest that up to 40 ppm of the total 100 ppm atmospheric pCO2 reduction during the last ice age were driven by increased nutrient utilization in the SAZ and associated feedbacks on the deep <span class="hlt">ocean</span> alkalinity. Micro-nutrient fertilization by iron (Fe), contained in the airborne dust flux to the SAZ, is considered to be the prime factor that stimulated this elevated photosynthetic activity thus enhancing nutrient utilization. We present a millennial-scale record of the vertical stable carbon isotope gradient between subsurface and deep water (Δδ13C) in the SAZ spanning the past 350,000 years. The Δδ13C gradient, derived from planktonic and benthic foraminifera, reflects the efficiency of biological pump and is highly correlated (rxy = -0.67 with 95% confidence interval [0.63; 0.71], n=874) with the record of dust flux preserved in <span class="hlt">Antarctic</span> ice cores6. This strongly suggests that nutrient utilization in the SAZ was dynamically coupled to dust-induced Fe fertilization across both glacial-interglacial and faster millennial timescales. In concert with ventilation changes of the deep <span class="hlt">Southern</span> <span class="hlt">Ocean</span> this drove <span class="hlt">ocean</span>-atmosphere CO2 exchange and, ultimately, atmospheric pCO2 variability during the late Pleistocene.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMPP51A1041R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMPP51A1041R"><span>A <span class="hlt">Southern</span> <span class="hlt">Ocean</span> driver of atmospheric CO2</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ronge, T.; Geibert, W.; Lippold, J.; Lamy, F.; Schnetger, B.; Tiedemann, R.</p> <p>2017-12-01</p> <p> confident that the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> - represented here by the South Pacific - played the dominant role in the first rise in atmospheric CO2. In addition the observed deglacial SPOC strengthening may have supported the transport of warm CDW onto the shelf areas since the timing of retreating West <span class="hlt">Antarctic</span> ice sheets is in good agreement with our recent reconstructions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GBioC..31.1318Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GBioC..31.1318Z"><span>Characteristics of the surface water DMS and pCO2 distributions and their relationships in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, southeast Indian <span class="hlt">Ocean</span>, and northwest Pacific <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Miming; Marandino, C. A.; Chen, Liqi; Sun, Heng; Gao, Zhongyong; Park, Keyhong; Kim, Intae; Yang, Bo; Zhu, Tingting; Yan, Jinpei; Wang, Jianjun</p> <p>2017-08-01</p> <p><span class="hlt">Oceanic</span> dimethyl sulfide (DMS) is of interest due to its critical influence on atmospheric sulfur compounds in the marine atmosphere and its hypothesized significant role in global climate. High-resolution shipboard underway measurements of surface seawater DMS and the partial pressure of carbon dioxide (pCO2) were conducted in the Atlantic <span class="hlt">Ocean</span> and Indian <span class="hlt">Ocean</span> sectors of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (SO), the southeast Indian <span class="hlt">Ocean</span>, and the northwest Pacific <span class="hlt">Ocean</span> from February to April 2014 during the 30th Chinese <span class="hlt">Antarctic</span> Research Expedition. The SO, particularly in the region south of 58°S, had the highest mean surface seawater DMS concentration of 4.1 ± 8.3 nM (ranged from 0.1 to 73.2 nM) and lowest mean seawater pCO2 level of 337 ± 50 μatm (ranged from 221 to 411 μatm) over the entire cruise. Significant variations of surface seawater DMS and pCO2 in the seasonal ice zone (SIZ) of SO were observed, which are mainly controlled by biological process and sea ice activity. We found a significant negative relationship between DMS and pCO2 in the SO SIZ using 0.1° resolution, [DMS] seawater = -0.160 [pCO2] seawater + 61.3 (r2 = 0.594, n = 924, p < 0.001). We anticipate that the relationship may possibly be utilized to reconstruct the surface seawater DMS climatology in the SO SIZ. Further studies are necessary to improve the universality of this approach.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.1006K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.1006K"><span>Impact of asymmetry in the total ozone distribution in <span class="hlt">Antarctic</span> region to the South <span class="hlt">Ocean</span> ecosystem</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kovalenok, S.; Evtushevsky, A.; Grytsai, A.; Milinevsky, G.</p> <p>2009-04-01</p> <p>Impact of asymmetry in the total ozone distribution in <span class="hlt">Antarctic</span> region to South <span class="hlt">Ocean</span> ecosystem is studied. The existence of the considerable zonal asymmetry in total ozone distribution over Antarctica observed last decades based on the satellite TOMS measurements in 1979-2005 due to existence of quasi-stationary planetary waves in a polar stratosphere. As was shown by authors earlier in the latitudinal interval of 55-75°S in <span class="hlt">Antarctic</span> spring months (Sep-Nov) the region of zonal total ozone minimum experienced the systematic spatial drift to the east. In the same period a minimum and maximum of quasi-stationary wave in TOC distribution are located: minimum over the <span class="hlt">Antarctic</span> Peninsula and Weddell Sea area, and maximum in the Ross Sea area. We expect that zonal asymmetry in total ozone distribution and its long-term spatial changes should impact to South <span class="hlt">Ocean</span> ecosystem food chain, especially in primary level. The systematic eastern shift of the quasi-stationary minimum in ozone distribution over north Weddell Sea area should cause the increased UV radiation on sea surface in comparison to Ross Sea area, where the lack of UVR should exist in spring month. To study this influence the available data of phytoplankton distribution in South <span class="hlt">Ocean</span> in 1997-2007 were analyzed. The results of analysis in connections with <span class="hlt">Antarctic</span> Peninsula regional climate warming are discussed. The research was partly supported by project 06BF051-12 of the National Taras Shevchenko University of Kyiv.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUFMOS62D..10R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFMOS62D..10R"><span>Trends in the Zonal Winds over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> from the NCEP/NCAR Reanalysis and Scatterometers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Richman, J. G.</p> <p>2002-12-01</p> <p>The winds over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> for the entire 54-year (1948-2001) period of the NCEP/NCAR Reanalysis have been decomposed into Principal Components (Empirical Orthogonal Functions). The first EOF describes 83 percent of the variance in the zonal wind. The loading of the EOF shows the predominately westerly surface flow with strongest winds in the Indian sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. The structure of this EOF is similar to the <span class="hlt">Southern</span> Annular Mode (SAM) identified by Thompson, et al 2000. The amplitude of this EOF reveals a large trend of 4.42 cm/s/yr in the strength of the zonal wind corresponding to a nearly 50 percent increase in the wind stress over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Such a trend, if real, would be important in the dynamics of the <span class="hlt">Antarctic</span> Circumpolar Current (ACC). Recent studies by Gille, et al. (2001), Olbers and Ivchenko (2001) and Gent et al. (2001) have shown that the transport of the ACC is correlated to the variability in the zonal wind with a monotonic increase in the transport with increasing zonal wind strength. However, errors in the data assimilation scheme for surface pressure observations on the <span class="hlt">Antarctic</span> continent appears to have caused a spurious trend in the sea level pressure south of 40S of -0.2 hPa/yr (Hines, et al. 2000 and Marshall, 2002). The sea level pressure difference between 40S and 60S has risen by 8 hPa over the same period. This sea level pressure difference is used as a proxy for the strength of the zonal winds. Thus, the trend in the zonal wind EOF amplitude may be an artifact of model errors in the NCEP Reanalysis. To check this trend, we analyzed scatterometer winds over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> from the SEASAT, ERS (1 and 2), NSCAT and QuikScat satellites. The scatterometer data is not used in the NCEP Reanalysis and, thus, is an independent estimate of the winds. The SEASAT Scatterometer (SASS) operated for 90 days in July-September, 1978, while the ERS, NSCAT and QuikScat scatterometers provide a continuous dataset from</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25489069','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25489069"><span>Impact of <span class="hlt">Antarctic</span> mixed-phase clouds on climate.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lawson, R Paul; Gettelman, Andrew</p> <p>2014-12-23</p> <p>Precious little is known about the composition of low-level clouds over the <span class="hlt">Antarctic</span> Plateau and their effect on climate. In situ measurements at the South Pole using a unique tethered balloon system and ground-based lidar reveal a much higher than anticipated incidence of low-level, mixed-phase clouds (i.e., consisting of supercooled liquid water drops and ice crystals). The high incidence of mixed-phase clouds is currently poorly represented in global climate models (GCMs). As a result, the effects that mixed-phase clouds have on climate predictions are highly uncertain. We modify the National Center for Atmospheric Research (NCAR) Community Earth System Model (CESM) GCM to align with the new observations and evaluate the radiative effects on a continental scale. The net cloud radiative effects (CREs) over Antarctica are increased by +7.4 Wm(-2), and although this is a significant change, a much larger effect occurs when the modified model physics are extended beyond the <span class="hlt">Antarctic</span> continent. The simulations show significant net CRE over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> storm tracks, where recent measurements also indicate substantial regions of supercooled liquid. These sensitivity tests confirm that <span class="hlt">Southern</span> <span class="hlt">Ocean</span> CREs are strongly sensitive to mixed-phase clouds colder than -20 °C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1235101-impact-antarctic-mixed-phase-clouds-climate','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1235101-impact-antarctic-mixed-phase-clouds-climate"><span>Impact of <span class="hlt">Antarctic</span> mixed-phase clouds on climate</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Lawson, R. Paul; Gettelman, Andrew</p> <p>2014-12-08</p> <p>Precious little is known about the composition of low-level clouds over the <span class="hlt">Antarctic</span> Plateau and their effect on climate. In situ measurements at the South Pole using a unique tethered balloon system and ground-based lidar reveal a much higher than anticipated incidence of low-level, mixed-phase clouds (i.e., consisting of supercooled liquid water drops and ice crystals). The high incidence of mixed-phase clouds is currently poorly represented in global climate models (GCMs). As a result, the effects that mixed-phase clouds have on climate predictions are highly uncertain. In this paper, we modify the National Center for Atmospheric Research (NCAR) Community Earthmore » System Model (CESM) GCM to align with the new observations and evaluate the radiative effects on a continental scale. The net cloud radiative effects (CREs) over Antarctica are increased by +7.4 Wm –2, and although this is a significant change, a much larger effect occurs when the modified model physics are extended beyond the <span class="hlt">Antarctic</span> continent. The simulations show significant net CRE over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> storm tracks, where recent measurements also indicate substantial regions of supercooled liquid. Finally, these sensitivity tests confirm that <span class="hlt">Southern</span> <span class="hlt">Ocean</span> CREs are strongly sensitive to mixed-phase clouds colder than –20 °C.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4280591','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4280591"><span>Impact of <span class="hlt">Antarctic</span> mixed-phase clouds on climate</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Lawson, R. Paul; Gettelman, Andrew</p> <p>2014-01-01</p> <p>Precious little is known about the composition of low-level clouds over the <span class="hlt">Antarctic</span> Plateau and their effect on climate. In situ measurements at the South Pole using a unique tethered balloon system and ground-based lidar reveal a much higher than anticipated incidence of low-level, mixed-phase clouds (i.e., consisting of supercooled liquid water drops and ice crystals). The high incidence of mixed-phase clouds is currently poorly represented in global climate models (GCMs). As a result, the effects that mixed-phase clouds have on climate predictions are highly uncertain. We modify the National Center for Atmospheric Research (NCAR) Community Earth System Model (CESM) GCM to align with the new observations and evaluate the radiative effects on a continental scale. The net cloud radiative effects (CREs) over Antarctica are increased by +7.4 Wm−2, and although this is a significant change, a much larger effect occurs when the modified model physics are extended beyond the <span class="hlt">Antarctic</span> continent. The simulations show significant net CRE over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> storm tracks, where recent measurements also indicate substantial regions of supercooled liquid. These sensitivity tests confirm that <span class="hlt">Southern</span> <span class="hlt">Ocean</span> CREs are strongly sensitive to mixed-phase clouds colder than −20 °C. PMID:25489069</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016E%26PSL.453..243Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016E%26PSL.453..243Z"><span><span class="hlt">Antarctic</span> link with East Asian summer monsoon variability during the Heinrich Stadial-Bølling interstadial transition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Hongbin; Griffiths, Michael L.; Huang, Junhua; Cai, Yanjun; Wang, Canfa; Zhang, Fan; Cheng, Hai; Ning, Youfeng; Hu, Chaoyong; Xie, Shucheng</p> <p>2016-11-01</p> <p>Previous research has shown a strong persistence for direct teleconnections between the East Asian summer monsoon (EASM) and high northern latitude climate variability during the last glacial and deglaciation, in particular between monsoon weakening and a reduced Atlantic meridional overturning circulation (AMOC). However, less attention has been paid to EASM strengthening as the AMOC was reinvigorated following peak Northern Hemisphere (NH) cooling. Moreover, climate model simulations have suggested a strong role for <span class="hlt">Antarctic</span> meltwater discharge in modulating northward heat transport and hence NH warming, yet the degree to which <span class="hlt">Southern</span> Hemisphere (SH) climate anomalies impacted the Asian monsoon region is still unclear. Here we present a new stalagmite oxygen-isotope record from the EASM affected region of central China, which documents two prominent stages of increased 18O-depleted moisture delivery to the region through the transition from Heinrich Stadial 1 (HS1) to the Bølling-Allerød (B-A) interstadial; this is in general agreement with the other monsoonal records from both NH and SH mid to low latitudes. Through novel comparisons with a recent iceberg-rafted debris (IRD) record from the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, we propose that the two-stage EASM intensification observed in our speleothem records were linked with two massive <span class="hlt">Antarctic</span> icesheet discharge (AID) events at ∼16.0 ka and ∼14.7 ka, immediately following the peak HS1 stadial event. Notably, the large increase in EASM intensity at the beginning of the HS1/B-A transition (∼16 ka) is relatively muted in the NH higher latitudes, and better aligns with the changes observed in the SH, indicating the <span class="hlt">Antarctic</span> and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> perturbations could have an active role in driving the initial EASM strengthening at this time. Indeed, <span class="hlt">Antarctic</span> freshwater input to the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> during these AID events would have cooled the surrounding surface waters and caused an expansion of sea ice, restricting the</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSPC14E2102M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSPC14E2102M"><span>Global decadal climate variability driven by <span class="hlt">Southern</span> <span class="hlt">Ocean</span> convection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marinov, I.; Cabre, A.</p> <p>2016-02-01</p> <p>Here we suggest a set of new "teleconnections" by which the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (SO) can induce anomalies in the tropical <span class="hlt">oceans</span> and atmosphere. A 5000-year long control simulation in a coupled atmosphere-<span class="hlt">ocean</span> model (CM2Mc, a low-resolution GFDL model) shows a natural, highly regular multi-decadal oscillation between periods of SO open sea convection and non-convective periods. This process happens naturally, with different frequencies and durations of convection across the majority of CMIP5 under preindustrial forcing (deLavergne et al., 2014). In our model, oscillations in Weddell Sea convection drive multidecadal variability in SO and global SSTs, as well as SO heat storage, with convective decades warm due to the heat released from the Circumpolar Deep Water and non-convective decades cold due to subsurface heat storage. Convective pulses drive local SST and sea ice variations south of 60S, immediately triggering changes in the Ferrell and Hadley cells, atmospheric energy budget and cross-equatorial heat exchange, ultimately influencing the position of the Intertropical Convergence Zone and rain patterns in the tropics. Additionally, the SO convection pulse is propagated to the tropics and the North Atlantic MOC via <span class="hlt">oceanic</span> pathways on relatively fast (decadal) timescales, in agreement with recent observational constraints. Open sea convection is the major mode of <span class="hlt">Antarctic</span> Bottom Water (AABW) formation in the CMIP5 models. Future improvements in the representation of shelf convection and sea-ice interaction in the SO are a clear necessity. These model improvements should render the AABW representation more realistic, and might influence (a) the connectivity of the SO with the rest of the planet, as described above and (b) the <span class="hlt">oceanic</span> and global carbon cycle, of which the AABW is a fundamental conduit.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29061120','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29061120"><span>Transcriptomic response of the <span class="hlt">Antarctic</span> pteropod Limacina helicina antarctica to <span class="hlt">ocean</span> acidification.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Johnson, Kevin M; Hofmann, Gretchen E</p> <p>2017-10-23</p> <p><span class="hlt">Ocean</span> acidification (OA), a change in <span class="hlt">ocean</span> chemistry due to the absorption of atmospheric CO 2 into surface <span class="hlt">oceans</span>, challenges biogenic calcification in many marine organisms. <span class="hlt">Ocean</span> acidification is expected to rapidly progress in polar seas, with regions of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> expected to experience severe OA within decades. Biologically, the consequences of OA challenge calcification processes and impose an energetic cost. In order to better characterize the response of a polar calcifier to conditions of OA, we assessed differential gene expression in the <span class="hlt">Antarctic</span> pteropod, Limacina helicina antarctica. Experimental levels of pCO 2 were chosen to create both contemporary pH conditions, and to mimic future pH expected in OA scenarios. Significant changes in the transcriptome were observed when juvenile L. h. antarctica were acclimated for 21 days to low-pH (7.71), mid-pH (7.9) or high-pH (8.13) conditions. Differential gene expression analysis of individuals maintained in the low-pH treatment identified down-regulation of genes involved in cytoskeletal structure, lipid transport, and metabolism. High pH exposure led to increased expression and enrichment for genes involved in shell formation, calcium ion binding, and DNA binding. Significant differential gene expression was observed in four major cellular and physiological processes: shell formation, the cellular stress response, metabolism, and neural function. Across these functional groups, exposure to conditions that mimic <span class="hlt">ocean</span> acidification led to rapid suppression of gene expression. Results of this study demonstrated that the transcriptome of the juvenile pteropod, L. h. antarctica, was dynamic and changed in response to different levels of pCO 2 . In a global change context, exposure of L. h. antarctica to the low pH, high pCO 2 OA conditions resulted in a suppression of transcripts for genes involved in key physiological processes: calcification, metabolism, and the cellular stress response. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29540750','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29540750"><span>Recent high-resolution <span class="hlt">Antarctic</span> ice velocity maps reveal increased mass loss in Wilkes Land, East Antarctica.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shen, Qiang; Wang, Hansheng; Shum, C K; Jiang, Liming; Hsu, Hou Tse; Dong, Jinglong</p> <p>2018-03-14</p> <p>We constructed <span class="hlt">Antarctic</span> ice velocity maps from Landsat 8 images for the years 2014 and 2015 at a high spatial resolution (100 m). These maps were assembled from 10,690 scenes of displacement vectors inferred from more than 10,000 optical images acquired from December 2013 through March 2016. We estimated the mass discharge of the <span class="hlt">Antarctic</span> ice sheet in 2008, 2014, and 2015 using the Landsat ice velocity maps, interferometric synthetic aperture radar (InSAR)-derived ice velocity maps (~2008) available from prior studies, and ice thickness data. An increased mass discharge (53 ± 14 Gt yr -1 ) was found in the East Indian <span class="hlt">Ocean</span> sector since 2008 due to unexpected widespread glacial acceleration in Wilkes Land, East Antarctica, while the other five <span class="hlt">oceanic</span> sectors did not exhibit significant changes. However, present-day increased mass loss was found by previous studies predominantly in west Antarctica and the <span class="hlt">Antarctic</span> Peninsula. The newly discovered increased mass loss in Wilkes Land suggests that the <span class="hlt">ocean</span> heat flux may already be influencing ice dynamics in the marine-based sector of the East <span class="hlt">Antarctic</span> ice sheet (EAIS). The marine-based sector could be adversely impacted by ongoing warming in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, and this process may be conducive to destabilization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.V43F..07C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.V43F..07C"><span>Volcanism, Iron, and Phytoplankton in the Heard and McDonald Islands Region, <span class="hlt">Southern</span> Indian <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Coffin, M. F.; Arculus, R. J.; Bowie, A. R.; Chase, Z.; Robertson, R.; Trull, T. W.; Heobi in2016 v01 Shipboard Party, T.</p> <p>2016-12-01</p> <p>Phytoplankton supply approximately half of the oxygen in Earth's atmosphere, and iron supply limits the growth of phytoplankton in the anemic <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Situated entirely within the Indian <span class="hlt">Ocean</span> sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> are Australia's only active subaerial volcanoes, Heard and McDonald islands (HIMI) on the central Kerguelen Plateau, a large igneous province. Widespread fields of submarine volcanoes, some of which may be active, extend for distances of up to several hundred kilometers from the islands. The predominantly eastward-flowing <span class="hlt">Antarctic</span> Circumpolar Current sweeps across the central Kerguelen Plateau, and extensive blooms of phytoplankton are observed on the Plateau down-current of HIMI. The goal of RV Investigator voyage IN2016_V01, conducted in January/February 2016, is to test the hypothesis that hydrothermal fluids, which cool active submarine volcanoes in the HIMI region, ascend from the seafloor and fertilise surface waters with iron, thereby enhancing biological productivity beginning with phytoplankton. Significant initial shipboard results include: Documentation, for the first time, of the role of active HIMI and nearby submarine volcanoes in supplying iron to the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Nearshore waters had elevated dissolved iron levels. Although biomass was not correspondingly elevated, fluorescence induction data indicated highly productive resident phytoplankton. Discovery of >200 acoustic plumes emanating from the seafloor and ascending up to tens of meters into the water column near HIMI. Deep tow camera footage shows bubbles rising from the seafloor in an acoustic plume field north of Heard Island. Mapping 1,000 km2 of uncharted seafloor around HIMI. Submarine volcanic edifices punctuate the adjacent seafloor, and yielded iron-rich rocks similar to those found on HIMI, respectively. Acoustic plumes emanating from some of these features suggest active seafloor hydrothermal systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.1705F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.1705F"><span>Heat fluxes across the <span class="hlt">Antarctic</span> Circumpolar Current</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ferrari, Ramiro; Provost, Christine; Hyang Park, Young; Sennéchael, Nathalie; Garric, Gilles; Bourdallé-Badie, Romain</p> <p>2014-05-01</p> <p>Determining the processes responsible for the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> heat balance is fundamental to our understanding of the weather and climate systems. Therefore, in the last decades, various studies aimed at analyzing the major mechanisms of the <span class="hlt">oceanic</span> poleward heat flux in this region. Previous works stipulated that the cross-stream heat flux due to the mesoscale transient eddies was responsible for the total meridional heat transport across the <span class="hlt">Antarctic</span> Circumpolar Current (ACC). Several numerical modelling and current meters data studies have recently challenged this idea. These showed that the heat flux due to the mean flow in the <span class="hlt">southern</span> part of the <span class="hlt">Antarctic</span> Circumpolar Current could be larger than the eddy heat flux contribution by two orders of magnitude. Eddy heat flux and heat flux by the mean flow distributions of were examined in Drake Passage using in situ measurements collected during the DRAKE 2006-9 project (from January 2006 to March 2009), available observations from the historical DRAKE 79 experiment and high resolution model outputs (ORCA 12, MERCATOR). The Drake Passage estimations provided a limited view of heat transport in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. The small spatial scales shown by the model derived heat flux by the mean flow indicate that circumpolar extrapolations from a single point observation are perilous. The importance of the heat flux due by the mean flow should be further investigated using other in situ observations and numerical model outputs. Similar situation has been observed, with important implication for heat flux due to the mean flow, in other topographically constricted regions with strong flow across prominent submarine ridges (choke points). We have estimated the heat flux due to the mean flow revisiting other ACC mooring sites where in situ time series are available, e.g. south of Australia (Tasmania) (Phillips and Rintoul, 2000), southeast of New Zealand (Campbell Plateau) (Bryden and Heath, 1985). Heat fluxes due to the mean</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23903871','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23903871"><span>Vulnerability of polar <span class="hlt">oceans</span> to anthropogenic acidification: comparison of arctic and <span class="hlt">antarctic</span> seasonal cycles.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shadwick, E H; Trull, T W; Thomas, H; Gibson, J A E</p> <p>2013-01-01</p> <p>Polar <span class="hlt">oceans</span> are chemically sensitive to anthropogenic acidification due to their relatively low alkalinity and correspondingly weak carbonate buffering capacity. Here, we compare unique CO2 system observations covering complete annual cycles at an Arctic (Amundsen Gulf) and <span class="hlt">Antarctic</span> site (Prydz Bay). The Arctic site experiences greater seasonal warming (10 vs 3°C), and freshening (3 vs 2), has lower alkalinity (2220 vs 2320 μmol/kg), and lower summer pH (8.15 vs 8.5), than the <span class="hlt">Antarctic</span> site. Despite a larger uptake of inorganic carbon by summer photosynthesis, the Arctic carbon system exhibits smaller seasonal changes than the more alkaline <span class="hlt">Antarctic</span> system. In addition, the excess surface nutrients in the <span class="hlt">Antarctic</span> may allow mitigation of acidification, via CO2 removal by enhanced summer production driven by iron inputs from glacial and sea-ice melting. These differences suggest that the Arctic system is more vulnerable to anthropogenic change due to lower alkalinity, enhanced warming, and nutrient limitation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3730166','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3730166"><span>Vulnerability of Polar <span class="hlt">Oceans</span> to Anthropogenic Acidification: Comparison of Arctic and <span class="hlt">Antarctic</span> Seasonal Cycles</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Shadwick, E. H.; Trull, T. W.; Thomas, H.; Gibson, J. A. E.</p> <p>2013-01-01</p> <p>Polar <span class="hlt">oceans</span> are chemically sensitive to anthropogenic acidification due to their relatively low alkalinity and correspondingly weak carbonate buffering capacity. Here, we compare unique CO2 system observations covering complete annual cycles at an Arctic (Amundsen Gulf) and <span class="hlt">Antarctic</span> site (Prydz Bay). The Arctic site experiences greater seasonal warming (10 vs 3°C), and freshening (3 vs 2), has lower alkalinity (2220 vs 2320 μmol/kg), and lower summer pH (8.15 vs 8.5), than the <span class="hlt">Antarctic</span> site. Despite a larger uptake of inorganic carbon by summer photosynthesis, the Arctic carbon system exhibits smaller seasonal changes than the more alkaline <span class="hlt">Antarctic</span> system. In addition, the excess surface nutrients in the <span class="hlt">Antarctic</span> may allow mitigation of acidification, via CO2 removal by enhanced summer production driven by iron inputs from glacial and sea-ice melting. These differences suggest that the Arctic system is more vulnerable to anthropogenic change due to lower alkalinity, enhanced warming, and nutrient limitation. PMID:23903871</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20840607','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20840607"><span>Contrasted demographic responses facing future climate change in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> seabirds.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Barbraud, Christophe; Rivalan, Philippe; Inchausti, Pablo; Nevoux, Marie; Rolland, Virginie; Weimerskirch, Henri</p> <p>2011-01-01</p> <p>1. Recent climate change has affected a wide range of species, but predicting population responses to projected climate change using population dynamics theory and models remains challenging, and very few attempts have been made. The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> sea surface temperature and sea ice extent are projected to warm and shrink as concentrations of atmospheric greenhouse gases increase, and several top predator species are affected by fluctuations in these oceanographic variables. 2. We compared and projected the population responses of three seabird species living in sub-tropical, sub-<span class="hlt">Antarctic</span> and <span class="hlt">Antarctic</span> biomes to predicted climate change over the next 50 years. Using stochastic population models we combined long-term demographic datasets and projections of sea surface temperature and sea ice extent for three different IPCC emission scenarios (from most to least severe: A1B, A2, B1) from general circulation models of Earth's climate. 3. We found that climate mostly affected the probability to breed successfully, and in one case adult survival. Interestingly, frequent nonlinear relationships in demographic responses to climate were detected. Models forced by future predicted climatic change provided contrasted population responses depending on the species considered. The northernmost distributed species was predicted to be little affected by a future warming of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, whereas steep declines were projected for the more southerly distributed species due to sea surface temperature warming and decrease in sea ice extent. For the most southerly distributed species, the A1B and B1 emission scenarios were respectively the most and less damaging. For the two other species, population responses were similar for all emission scenarios. 4. This is among the first attempts to study the demographic responses for several populations with contrasted environmental conditions, which illustrates that investigating the effects of climate change on core population dynamics</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21253607','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21253607"><span><span class="hlt">Antarctic</span> krill 454 pyrosequencing reveals chaperone and stress transcriptome.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Clark, Melody S; Thorne, Michael A S; Toullec, Jean-Yves; Meng, Yan; Guan, Le Luo; Peck, Lloyd S; Moore, Stephen</p> <p>2011-01-06</p> <p>The <span class="hlt">Antarctic</span> krill Euphausia superba is a keystone species in the <span class="hlt">Antarctic</span> food chain. Not only is it a significant grazer of phytoplankton, but it is also a major food item for charismatic megafauna such as whales and seals and an important <span class="hlt">Southern</span> <span class="hlt">Ocean</span> fisheries crop. Ecological data suggest that this species is being affected by climate change and this will have considerable consequences for the balance of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ecosystem. Hence, understanding how this organism functions is a priority area and will provide fundamental data for life history studies, energy budget calculations and food web models. The assembly of the 454 transcriptome of E. superba resulted in 22,177 contigs with an average size of 492bp (ranging between 137 and 8515bp). In depth analysis of the data revealed an extensive catalogue of the cellular chaperone systems and the major antioxidant proteins. Full length sequences were characterised for the chaperones HSP70, HSP90 and the super-oxide dismutase antioxidants, with the discovery of potentially novel duplications of these genes. The sequence data contained 41,470 microsatellites and 17,776 Single Nucleotide Polymorphisms (SNPs/INDELS), providing a resource for population and also gene function studies. This paper details the first 454 generated data for a pelagic <span class="hlt">Antarctic</span> species or any pelagic crustacean globally. The classical "stress proteins", such as HSP70, HSP90, ferritin and GST were all highly expressed. These genes were shown to be over expressed in the transcriptomes of <span class="hlt">Antarctic</span> notothenioid fish and hypothesized as adaptations to living in the cold, with the associated problems of decreased protein folding efficiency and increased vulnerability to damage by reactive oxygen species. Hence, these data will provide a major resource for future physiological work on krill, but in particular a suite of "stress" genes for studies understanding marine ectotherms' capacities to cope with environmental change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.1821W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.1821W"><span>Satellite microwave observations of the interannual variability of snowmelt on sea ice in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Willmes, S.; Haas, C.; Nicolaus, M.; Bareiss, J.</p> <p>2009-04-01</p> <p>Snowmelt processes on <span class="hlt">Antarctic</span> sea ice are examined. We present a simple snowmelt indicator based on diurnal brightness temperature variations from microwave satellite data. The method is validated through extensive field data from the western Weddell Sea and lends itself to the investigation of interannual and spatial variations of the typical snowmelt on <span class="hlt">Antarctic</span> sea ice. We use in situ measurements of physical snow properties to show that despite the absence of strong melting, the summer period is distinct from all other seasons with enhanced diurnal variations of snow wetness. A microwave emission model reveals that repeated thawing and refreezing causes the typical microwave emissivity signatures that are found on perennial <span class="hlt">Antarctic</span> sea ice during summer. The proposed melt indicator accounts for the characteristic phenomenological stages of snowmelt in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and detects the onset of diurnal snow wetting. An algorithm is presented to map large-scale snowmelt onset, based on satellite data from the period between 1988 and 2006. The results indicate strong meridional gradients of snowmelt onset with the Weddell, Amundsen and Ross Seas showing earliest (beginning of October) and most frequent snowmelt. Moreover, a distinct interannual variability of melt onset dates and large areas of first-year ice where no diurnal freeze-thawing occurs at the surface are determined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JGRC..114.3006W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JGRC..114.3006W"><span>Satellite microwave observations of the interannual variability of snowmelt on sea ice in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Willmes, Sascha; Haas, Christian; Nicolaus, Marcel; Bareiss, JöRg</p> <p>2009-03-01</p> <p>Snowmelt processes on <span class="hlt">Antarctic</span> sea ice are examined. We present a simple snowmelt indicator based on diurnal brightness temperature variations from microwave satellite data. The method is validated through extensive field data from the western Weddell Sea and lends itself to the investigation of interannual and spatial variations of the typical snowmelt on <span class="hlt">Antarctic</span> sea ice. We use in-situ measurements of physical snow properties to show that despite the absence of strong melting, the summer period is distinct from all other seasons with enhanced diurnal variations of snow wetness. A microwave emission model reveals that repeated thawing and refreezing cause the typical microwave emissivity signatures that are found on perennial <span class="hlt">Antarctic</span> sea ice during summer. The proposed melt indicator accounts for the characteristic phenomenological stages of snowmelt in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and detects the onset of diurnal snow wetting. An algorithm is presented to map large-scale snowmelt onset based on satellite data from the period between 1988 and 2006. The results indicate strong meridional gradients of snowmelt onset with the Weddell, Amundsen, and Ross Seas showing earliest (beginning of October) and most frequent snowmelt. Moreover, a distinct interannual variability of melt onset dates and large areas of first-year ice where no diurnal freeze thawing occurs at the surface are determined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3479616','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3479616"><span>Dynamics of the last glacial maximum <span class="hlt">Antarctic</span> ice-sheet and its response to <span class="hlt">ocean</span> forcing</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Golledge, Nicholas R.; Fogwill, Christopher J.; Mackintosh, Andrew N.; Buckley, Kevin M.</p> <p>2012-01-01</p> <p>Retreat of the Last Glacial Maximum (LGM) <span class="hlt">Antarctic</span> ice sheet is thought to have been initiated by changes in <span class="hlt">ocean</span> heat and eustatic sea level propagated from the Northern Hemisphere (NH) as northern ice sheets melted under rising atmospheric temperatures. The extent to which spatial variability in ice dynamics may have modulated the resultant pattern and timing of decay of the <span class="hlt">Antarctic</span> ice sheet has so far received little attention, however, despite the growing recognition that dynamic effects account for a sizeable proportion of mass-balance changes observed in modern ice sheets. Here we use a 5-km resolution whole-continent numerical ice-sheet model to assess whether differences in the mechanisms governing ice sheet flow could account for discrepancies between geochronological studies in different parts of the continent. We first simulate the geometry and flow characteristics of an equilibrium LGM ice sheet, using pan-<span class="hlt">Antarctic</span> terrestrial and marine geological data for constraint, then perturb the system with sea level and <span class="hlt">ocean</span> heat flux increases to investigate ice-sheet vulnerability. Our results identify that fast-flowing glaciers in the eastern Weddell Sea, the Amundsen Sea, central Ross Sea, and in the Amery Trough respond most rapidly to <span class="hlt">ocean</span> forcings, in agreement with empirical data. Most significantly, we find that although <span class="hlt">ocean</span> warming and sea-level rise bring about mainly localized glacier acceleration, concomitant drawdown of ice from neighboring areas leads to widespread thinning of entire glacier catchments—a discovery that has important ramifications for the dynamic changes presently being observed in modern ice sheets. PMID:22988078</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22988078','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22988078"><span>Dynamics of the last glacial maximum <span class="hlt">Antarctic</span> ice-sheet and its response to <span class="hlt">ocean</span> forcing.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Golledge, Nicholas R; Fogwill, Christopher J; Mackintosh, Andrew N; Buckley, Kevin M</p> <p>2012-10-02</p> <p>Retreat of the Last Glacial Maximum (LGM) <span class="hlt">Antarctic</span> ice sheet is thought to have been initiated by changes in <span class="hlt">ocean</span> heat and eustatic sea level propagated from the Northern Hemisphere (NH) as northern ice sheets melted under rising atmospheric temperatures. The extent to which spatial variability in ice dynamics may have modulated the resultant pattern and timing of decay of the <span class="hlt">Antarctic</span> ice sheet has so far received little attention, however, despite the growing recognition that dynamic effects account for a sizeable proportion of mass-balance changes observed in modern ice sheets. Here we use a 5-km resolution whole-continent numerical ice-sheet model to assess whether differences in the mechanisms governing ice sheet flow could account for discrepancies between geochronological studies in different parts of the continent. We first simulate the geometry and flow characteristics of an equilibrium LGM ice sheet, using pan-<span class="hlt">Antarctic</span> terrestrial and marine geological data for constraint, then perturb the system with sea level and <span class="hlt">ocean</span> heat flux increases to investigate ice-sheet vulnerability. Our results identify that fast-flowing glaciers in the eastern Weddell Sea, the Amundsen Sea, central Ross Sea, and in the Amery Trough respond most rapidly to <span class="hlt">ocean</span> forcings, in agreement with empirical data. Most significantly, we find that although <span class="hlt">ocean</span> warming and sea-level rise bring about mainly localized glacier acceleration, concomitant drawdown of ice from neighboring areas leads to widespread thinning of entire glacier catchments-a discovery that has important ramifications for the dynamic changes presently being observed in modern ice sheets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSHE52B..08C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSHE52B..08C"><span>An Integrative Approach to Understand a Rich Ecosystem in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> From Carbon to Top Predators</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cotté, C.; d'Ovidio, F.; Behagle, N.; Roudaut, G.; Brehmer, P.; Bost, C. A.; Guinet, C.; Cherel, Y.</p> <p>2016-02-01</p> <p>Large parts of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> waters are rich in macronutrients, but blooms of phytoplankton occur in a patchy and localized way. This is in part due to the presence of sources of limiting micronutrients scattered along the continental breaks, whose inputs are stirred into the open <span class="hlt">ocean</span> very inhomogeneously. At the highest levels of ecosystems, top predators reveal areas of ecological importance where no other information is available on the underpinning trophic web. A dramatic example of this situation is provided by the region around Kerguelen archipelago, in the <span class="hlt">Southern</span> Indian <span class="hlt">Ocean</span>. Here, the high nutrient, low iron waters transported eastward by the <span class="hlt">Antarctic</span> Circumpolar Current encounter the iron-rich Kerguelen shelf break. As a consequence, a plume of high chlorophyll water develops east of the plateau, extending from the shelf break for hundreds of kms into the open <span class="hlt">ocean</span>, and strongly modulated by the intense mesoscale activity. Large populations of top predators use this area to forage during the summer periode, despite very scarce knowledge on their micronektonic prey and on mid-trophic oragnisms. By combining in campaign data, satellite observations, and biologging, we adopt an end-to-end approach and describe the mechanisms by which the <span class="hlt">ocean</span> physics impacts the regional biogeochemistry firstly by redistributing iron-rich coastal waters into the open <span class="hlt">ocean</span>, and then by focusing on the trophic interactions. We consider in particular the role of mesoscale eddies and submesoscale fronts, whose temporal dynamics resonates with biological processes and organises the variability of ecosystems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018OcSci..14..105C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018OcSci..14..105C"><span>Using kinetic energy measurements from altimetry to detect shifts in the positions of fronts in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chambers, Don P.</p> <p>2018-02-01</p> <p>A novel analysis is performed utilizing cross-track kinetic energy (CKE) computed from along-track sea surface height anomalies. The midpoint of enhanced kinetic energy averaged over 3-year periods from 1993 to 2016 is determined across the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and examined to detect shifts in frontal positions, based on previous observations that kinetic energy is high around fronts in the <span class="hlt">Antarctic</span> Circumpolar Current system due to jet instabilities. It is demonstrated that although the CKE does not represent the full eddy kinetic energy (computed from crossovers), the shape of the enhanced regions along ground tracks is the same, and CKE has a much finer spatial sampling of 6.9 km. Results indicate no significant shift in the front positions across the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, on average, although there are some localized, large movements. This is consistent with other studies utilizing sea surface temperature gradients, the latitude of mean transport, and the probability of jet occurrence, but is inconsistent with studies utilizing the movement of contours of dynamic topography.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017E%26PSL.458...49C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017E%26PSL.458...49C"><span>Widespread <span class="hlt">Antarctic</span> glaciation during the Late Eocene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carter, Andrew; Riley, Teal R.; Hillenbrand, Claus-Dieter; Rittner, Martin</p> <p>2017-01-01</p> <p>Marine sedimentary rocks drilled on the southeastern margin of the South Orkney microcontinent in Antarctica (<span class="hlt">Ocean</span> Drilling Program Leg 113 Site 696) were deposited between ∼36.5 Ma to 33.6 Ma, across the Eocene-Oligocene climate transition. The recovered rocks contain abundant grains exhibiting mechanical features diagnostic of iceberg-rafted debris. Sand provenance based on a multi-proxy approach that included petrographic analysis of over 275,000 grains, detrital zircon geochronology and apatite thermochronometry rule out local sources (<span class="hlt">Antarctic</span> Peninsula or the South Orkney Islands) for the material. Instead the ice-transported grains show a clear provenance from the <span class="hlt">southern</span> Weddell Sea region, extending from the Ellsworth-Whitmore Mountains of West Antarctica to the coastal region of Dronning Maud Land in East Antarctica. This study provides the first evidence for a continuity of widespread glacier calving along the coastline of the <span class="hlt">southern</span> Weddell Sea embayment at least 2.5 million yrs before the prominent oxygen isotope event at 34-33.5 Ma that is considered to mark the onset of widespread glaciation of the <span class="hlt">Antarctic</span> continent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25898908','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25898908"><span>In situ observations of a possible skate nursery off the western <span class="hlt">Antarctic</span> Peninsula.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Amsler, M O; Smith, K E; McClintock, J B; Singh, H; Thatje, S; Vos, S C; Brothers, C J; Brown, A; Ellis, D; Anderson, J; Aronson, R B</p> <p>2015-06-01</p> <p>A dense aggregation of skate egg cases was imaged during a photographic survey of the sea floor along the western <span class="hlt">Antarctic</span> Peninsula in November 2013. Egg cases were noted in a narrow band between 394 and 443 m depth. Although some skate species in other <span class="hlt">oceans</span> are known to utilize restricted areas to deposit eggs in great numbers, such nurseries have not been described in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. © 2015 The Fisheries Society of the British Isles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1910612K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1910612K"><span>Mapping <span class="hlt">Antarctic</span> Crustal Thickness using Gravity Inversion and Comparison with Seismic Estimates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kusznir, Nick; Ferraccioli, Fausto; Jordan, Tom</p> <p>2017-04-01</p> <p>Using gravity anomaly inversion, we produce comprehensive regional maps of crustal thickness and <span class="hlt">oceanic</span> lithosphere distribution for Antarctica and the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Crustal thicknesses derived from gravity inversion are consistent with seismic estimates. We determine Moho depth, crustal basement thickness, continental lithosphere thinning (1-1/β) and <span class="hlt">ocean</span>-continent transition location using a 3D spectral domain gravity inversion method, which incorporates a lithosphere thermal gravity anomaly correction (Chappell & Kusznir 2008). The gravity anomaly contribution from ice thickness is included in the gravity inversion, as is the contribution from sediments which assumes a compaction controlled sediment density increase with depth. Data used in the gravity inversion are elevation and bathymetry, free-air gravity anomaly, the Bedmap 2 ice thickness and bedrock topography compilation south of 60 degrees south and relatively sparse constraints on sediment thickness. <span class="hlt">Ocean</span> isochrons are used to define the cooling age of <span class="hlt">oceanic</span> lithosphere. Crustal thicknesses from gravity inversion are compared with independent seismic estimates, which are still relatively sparse over Antarctica. Our gravity inversion study predicts thick crust (> 45 km) under interior East Antarctica, which is penetrated by narrow continental rifts featuring relatively thinner crust. The largest crustal thicknesses predicted from gravity inversion lie in the region of the Gamburtsev Subglacial Mountains, and are consistent with seismic estimates. The East <span class="hlt">Antarctic</span> Rift System (EARS), a major Permian to Cretaceous age rift system, is imaged by our inversion and appears to extend from the continental margin at the Lambert Rift to the South Pole region, a distance of 2500 km. Offshore an extensive region of either thick <span class="hlt">oceanic</span> crust or highly thinned continental crust lies adjacent to Oates Land and north Victoria Land, and also off West Antarctica around the Amundsen Ridges. Thin crust is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.G23C..06M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.G23C..06M"><span>Can we observe the fronts of the <span class="hlt">Antarctic</span> Circumpolar Current using GRACE OBP?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Makowski, J.; Chambers, D. P.; Bonin, J. A.</p> <p>2014-12-01</p> <p>The <span class="hlt">Antarctic</span> Circumpolar Current (ACC) and the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> remains one of the most undersampled regions of the world's <span class="hlt">oceans</span>. The ACC is comprised of four major fronts: the Sub-Tropical Front (STF), the Polar Front (PF), the Sub-<span class="hlt">Antarctic</span> Front (SAF), and the <span class="hlt">Southern</span> ACC Front (SACCF). These were initially observed individually from repeat hydrographic sections and their approximate locations globally have been quantified using all available temperature data from the World <span class="hlt">Ocean</span> and Climate Experiment (WOCE). More recent studies based on satellite altimetry have found that the front positions are more dynamic and have shifted south by up to 1° on average since 1993. Using <span class="hlt">ocean</span> bottom pressure (OBP) data from the current Gravity Recovery and Climate Experiment (GRACE) we have measured integrated transport variability of the ACC south of Australia. However, differentiation of variability of specific fronts has been impossible due to the necessary smoothing required to reduce noise and correlated errors in the measurements. The future GRACE Follow-on (GFO) mission and the post 2020 GRACE-II mission are expected to produce higher resolution gravity fields with a monthly temporal resolution. Here, we study the resolution and error characteristics of GRACE gravity data that would be required to resolve variations in the front locations and transport. To do this, we utilize output from a high-resolution model of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, hydrology models, and ice sheet surface mass balance models; add various amounts of random and correlated errors that may be expected from GFO and GRACE-II; and quantify requirements needed for future satellite gravity missions to resolve variations along the ACC fronts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997JGR...10216761C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997JGR...10216761C"><span>Annually resolved <span class="hlt">southern</span> hemisphere volcanic history from two <span class="hlt">Antarctic</span> ice cores</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cole-Dai, Jihong; Mosley-Thompson, Ellen; Thompson, Lonnie G.</p> <p>1997-07-01</p> <p>The continuous sulfate analysis of two <span class="hlt">Antarctic</span> ice cores, one from the <span class="hlt">Antarctic</span> Peninsula region and one from West Antarctica, provides an annually resolved proxy history of <span class="hlt">southern</span> semisphere volcanism since early in the 15th century. The dating is accurate within ±3 years due to the high rate of snow accumulation at both core sites and the small sample sizes used for analysis. The two sulfate records are consistent with each other. A systematic and objective method of separating outstanding sulfate events from the background sulfate flux is proposed and used to identify all volcanic signals. The resulting volcanic chronology covering 1417-1989 A.D. resolves temporal ambiguities about several recently discovered events. A number of previously unknown, moderate eruptions during late 1600s are uncovered in this chronology. The eruption of Tambora (1815) and the recently discovered eruption of Kuwae (1453) in the tropical South Pacific injected the greatest amount of sulfur dioxide into the <span class="hlt">southern</span> hemisphere stratosphere during the last half millennium. A technique for comparing the magnitude of volcanic events preserved within different ice cores is developed using normalized sulfate flux. For the same eruptions the variability of the volcanic sulfate flux between the cores is within ±20% of the sulfate flux from the Tambora eruption.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMPP11B1036R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMPP11B1036R"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> Circulation: a High Resolution Examination of the Last Deglaciation from Deep-Sea Corals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Robinson, L. F.; Li, T.; Chen, T.; Burke, A.; Pegrum Haram, A.; Stewart, J.; Rae, J. W. B.; van de Flierdt, T.; Struve, T.; Wilson, D. J.</p> <p>2017-12-01</p> <p>Two decades ago it was first noted that the skeletal remains of deep-sea corals had the potential to provide absolutely dated archives of past <span class="hlt">ocean</span> conditions. In the intervening twenty years this field has developed to the point where strategic collections and high throughput dating techniques now allow high resolution, well dated records of past deep sea behaviour to be produced. Likewise, efforts to improve understanding of biomineralisation and growth rates are leading to refinements in proxy tools useful for examining circulation, nutrient and carbon cycling, temperature and weathering processes. Deep-sea corals are particularly valuable archives in high latitude regions where radiocarbon-based age models are susceptible to large changes in surface reservoir ages. In this presentation we show new high resolution multiproxy records of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (Drake Passage) made on U-Th dated corals spanning the last glacial cycle. With more than seventeen hundred reconnaissance ages, and around 200 precise isotope dilution U-Th ages, subtle changes in <span class="hlt">ocean</span> behaviour can be identified during times of abrupt climate change. The geochemical signature of corals from the deepest sites, closest to modern day Lower Circumpolar Deep Waters, typically show a gradual shift from glacial to Holocene values during deglaciation, likely related to ventilation of the deep <span class="hlt">ocean</span>. By contrast for the samples collected shallower in the water column (within sites currently bathed by Upper Circumpolar Deep Waters and <span class="hlt">Antarctic</span> Intermediate and Mode Waters) the evidence points to a more complicated picture. Vertical zonation in the geochemical data suggests that periods of stratification are interspersed with mixing events within the upper 1500m of the water column. At the same time comparison to U-Th dated records from the low latitude Pacific and Atlantic points to an important role for the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in feeding the intermediate waters of both <span class="hlt">ocean</span> basins throughout the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRC..122.8661B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRC..122.8661B"><span>Oxygen in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> From Argo Floats: Determination of Processes Driving Air-Sea Fluxes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bushinsky, Seth M.; Gray, Alison R.; Johnson, Kenneth S.; Sarmiento, Jorge L.</p> <p>2017-11-01</p> <p>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is of outsized significance to the global oxygen and carbon cycles with relatively poor measurement coverage due to harsh winters and seasonal ice cover. In this study, we use recent advances in the parameterization of air-sea oxygen fluxes to analyze 9 years of oxygen data from a recalibrated Argo oxygen data set and from air-calibrated oxygen floats deployed as part of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Carbon and Climate Observations and Modeling (SOCCOM) project. From this combined data set of 150 floats, we find a total <span class="hlt">Southern</span> <span class="hlt">Ocean</span> oxygen sink of -183 ± 80 Tmol yr-1 (positive to the atmosphere), greater than prior estimates. The uptake occurs primarily in the Polar-Frontal <span class="hlt">Antarctic</span> Zone (PAZ, -94 ± 30 Tmol O2 yr-1) and Seasonal Ice Zone (SIZ, -111 ± 9.3 Tmol O2 yr-1). This flux is driven by wintertime ventilation, with a large portion of the flux in the SIZ passing through regions with fractional sea ice. The Subtropical Zone (STZ) is seasonally driven by thermal fluxes and exhibits a net outgassing of 47 ± 29 Tmol O2 yr-1 that is likely driven by biological production. The Subantarctic Zone (SAZ) uptake is -25 ± 12 Tmol O2 yr-1. Total oxygen fluxes were separated into a thermal and nonthermal component. The nonthermal flux is correlated with net primary production and mixed layer depth in the STZ, SAZ, and PAZ, but not in the SIZ where seasonal sea ice slows the air-sea gas flux response to the entrainment of deep, low-oxygen waters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.T13F..06T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.T13F..06T"><span>Turning up the Heat on the <span class="hlt">Antarctic</span> Ice Sheet (From Below): Challenges and Near-Term Opportunities for Measuring <span class="hlt">Antarctic</span> Geothermal Fluxes (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tulaczyk, S. M.; Hossainzadeh, S.</p> <p>2010-12-01</p> <p><span class="hlt">Antarctic</span> heat flow plays an important role in determining the rate of meltwater production at the base of the <span class="hlt">Antarctic</span> ice sheet. Basal meltwater represents a key control on ice sheet mass balance, <span class="hlt">Antarctic</span> geochemical fluxes into the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, and subglacial microbial habitats. However, direct measurements of heat flow are difficult in glaciated terrains. Vertical temperature profiles determined in ice boreholes are influenced by thermal energy fluxes associated with basal melting/freezing and have to be used with caution when calculating geothermal flux rates. Two published continent-wide geophysical estimates of <span class="hlt">Antarctic</span> geothermal fluxes provide valuable databases but are not fully consistent with each other and need to be verified by direct subglacial measurements. Planned drilling into <span class="hlt">Antarctic</span> subglacial environments will offer the opportunity to perform such measurements. Determination of temperature gradients in sedimentary sequences resting at the bottom of subglacial lakes will offer particularly useful insights. Temperature profiles in such environments will not be thermally or mechanically disturbed as it may be the case in till layers proximal to a sliding ice base. We will review plans for making such measurements as part of the WISSARD (Whillans Ice Stream Subglacial Access Research Drilling) project, which is scheduled to penetrate the West <span class="hlt">Antarctic</span> ice sheet in 2012-13 and 2013-14.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5013606','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5013606"><span>Source identification and distribution reveals the potential of the geochemical <span class="hlt">Antarctic</span> sea ice proxy IPSO25</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Belt, S. T.; Smik, L.; Brown, T. A.; Kim, J.-H.; Rowland, S. J.; Allen, C. S.; Gal, J.-K.; Shin, K.-H.; Lee, J. I.; Taylor, K. W. R.</p> <p>2016-01-01</p> <p>The presence of a di-unsaturated highly branched isoprenoid (HBI) lipid biomarker (diene II) in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> sediments has previously been proposed as a proxy measure of palaeo <span class="hlt">Antarctic</span> sea ice. Here we show that a source of diene II is the sympagic diatom Berkeleya adeliensis Medlin. Furthermore, the propensity for B. adeliensis to flourish in platelet ice is reflected by an offshore downward gradient in diene II concentration in >100 surface sediments from <span class="hlt">Antarctic</span> coastal and near-coastal environments. Since platelet ice formation is strongly associated with super-cooled freshwater inflow, we further hypothesize that sedimentary diene II provides a potentially sensitive proxy indicator of landfast sea ice influenced by meltwater discharge from nearby glaciers and ice shelves, and re-examination of some previous diene II downcore records supports this hypothesis. The term IPSO25—Ice Proxy for the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> with 25 carbon atoms—is proposed as a proxy name for diene II. PMID:27573030</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-GSFC_20171208_Archive_e000198.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-GSFC_20171208_Archive_e000198.html"><span>NASA Launches Eighth Year of <span class="hlt">Antarctic</span> Ice Change Airborne Survey</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-12-08</p> <p>At the <span class="hlt">southern</span> end of the Earth, a NASA plane carrying a team of scientists and a sophisticated instrument suite to study ice is returning to surveying Antarctica. For the past eight years, Operation IceBridge has been on a mission to build a record of how polar ice is evolving in a changing environment. The information IceBridge has gathered in the <span class="hlt">Antarctic</span>, which includes data on the thickness and shape of snow and ice, as well as the topography of the land and <span class="hlt">ocean</span> floor beneath the <span class="hlt">ocean</span> and the ice, has allowed scientists to determine that the West <span class="hlt">Antarctic</span> Ice Sheet may be in irreversible decline. Researchers have also used IceBridge data to evaluate climate models of Antarctica and map the bedrock underneath <span class="hlt">Antarctic</span> ice. Read more:http://go.nasa.gov/2dxczkd NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A21Q..08F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A21Q..08F"><span>Response of <span class="hlt">Antarctic</span> sea surface temperature and sea ice to ozone depletion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ferreira, D.; Gnanadesikan, A.; Kostov, Y.; Marshall, J.; Seviour, W.; Waugh, D.</p> <p>2017-12-01</p> <p>The influence of the <span class="hlt">Antarctic</span> ozone hole extends all the way from the stratosphere through the troposphere down to the surface, with clear signatures on surface winds, and SST during summer. In this talk we discuss the impact of these changes on the <span class="hlt">ocean</span> circulation and sea ice state. We are notably motivated by the observed cooling of the surface <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and associated increase in <span class="hlt">Antarctic</span> sea ice extent since the 1970s. These trends are not reproduced by CMIP5 climate models, and the underlying mechanism at work in nature and the models remain unexplained. Did the ozone hole contribute to the observed trends?Here, we review recent advances toward answering these issues using "abrupt ozone depletion" experiments. The <span class="hlt">ocean</span> and sea ice response is rather complex, comprising two timescales: a fast ( 1-2y) cooling of the surface <span class="hlt">ocean</span> and sea ice cover increase, followed by a slower warming trend, which, depending on models, flip the sign of the SST and sea ice responses on decadal timescale. Although the basic mechanism seems robust, comparison across climate models reveal large uncertainties in the timescales and amplitude of the response to the extent that even the sign of the <span class="hlt">ocean</span> and sea ice response to ozone hole and recovery remains unconstrained. After briefly describing the dynamics and thermodynamics behind the two-timescale response, we will discuss the main sources of uncertainties in the modeled response, namely cloud effects and air-sea heat exchanges, surface wind stress response and <span class="hlt">ocean</span> eddy transports. Finally, we will consider the implications of our results on the ability of coupled climate models to reproduce observed <span class="hlt">Southern</span> <span class="hlt">Ocean</span> changes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMPA32A..02V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMPA32A..02V"><span>Integrated Science and Logistical Planning to Support Big Questions in <span class="hlt">Antarctic</span> Science</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vaughan, D. G.; Stockings, T. M.</p> <p>2015-12-01</p> <p>Each year, British <span class="hlt">Antarctic</span> Survey (BAS) supports an extensive programme of science at five <span class="hlt">Antarctic</span> and sub-<span class="hlt">Antarctic</span> stations, ranging from the tiny Bird Island Research Station at 54°S in the South Atlantic, to the massive, and fully re-locatable, Halley Research Station on Brunt Ice Shelf at 75°S. The BAS logistics hub, Rothera Research Station on the <span class="hlt">Antarctic</span> Peninsula supports deployment of deep-field and airborne field campaigns through much of the <span class="hlt">Antarctic</span> continent, and an innovative new UK polar research vessel is under design, and planned to enter service in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in 2019. BAS's core science programme covering all aspects of physical, biological and geological science is delivered by our own science teams, but every year many other UK scientists and overseas collaborators also access BAS's <span class="hlt">Antarctic</span> logistics to support their own programmes. As an integrated science and logistics provider, BAS is continuously reviewing its capabilities and operational procedures to ensure that the future long-term requirements of science are optimally supported. Current trends are towards providing the capacity for heavier remote operations and larger-scale field camps, increasing use of autonomous <span class="hlt">ocean</span> and airborne platforms, and increasing opportunities to provide turnkey solutions for low-cost experimental deployments. This talk will review of expected trends in <span class="hlt">Antarctic</span> science and the opportunities to conduct science in Antarctica. It will outline the anticipated logistic developments required to support future stakeholder-led and strategically-directed science programmes, and the long-term ambitions of our science communities indentified in several recent horizon-scanning activities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRC..120..547M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRC..120..547M"><span>Circulation, retention, and mixing of waters within the Weddell-Scotia Confluence, <span class="hlt">Southern</span> <span class="hlt">Ocean</span>: The role of stratified Taylor columns</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meredith, Michael P.; Meijers, Andrew S.; Naveira Garabato, Alberto C.; Brown, Peter J.; Venables, Hugh J.; Abrahamsen, E. Povl; Jullion, Loïc.; Messias, Marie-José</p> <p>2015-01-01</p> <p>The waters of the Weddell-Scotia Confluence (WSC) lie above the rugged topography of the South Scotia Ridge in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Meridional exchanges across the WSC transfer water and tracers between the <span class="hlt">Antarctic</span> Circumpolar Current (ACC) to the north and the subpolar Weddell Gyre to the south. Here, we examine the role of topographic interactions in mediating these exchanges, and in modifying the waters transferred. A case study is presented using data from a free-drifting, intermediate-depth float, which circulated anticyclonically over Discovery Bank on the South Scotia Ridge for close to 4 years. Dimensional analysis indicates that the local conditions are conducive to the formation of Taylor columns. Contemporaneous ship-derived transient tracer data enable estimation of the rate of isopycnal mixing associated with this column, with values of O(1000 m2/s) obtained. Although necessarily coarse, this is of the same order as the rate of isopycnal mixing induced by transient mesoscale eddies within the ACC. A picture emerges of the Taylor column acting as a slow, steady blender, retaining the waters in the vicinity of the WSC for lengthy periods during which they can be subject to significant modification. A full regional float data set, bathymetric data, and a <span class="hlt">Southern</span> <span class="hlt">Ocean</span> state estimate are used to identify other potential sites for Taylor column formation. We find that they are likely to be sufficiently widespread to exert a significant influence on water mass modification and meridional fluxes across the <span class="hlt">southern</span> edge of the ACC in this sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..MARF12003C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..MARF12003C"><span>Spatial distirbution of <span class="hlt">Antarctic</span> mass flux due to iceberg transport</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Comeau, Darin; Hunke, Elizabeth; Turner, Adrian</p> <p></p> <p>Under a changing climate that sees amplified warming in the polar regions, the stability of the West <span class="hlt">Antarctic</span> ice sheet and its impact on sea level rise is of great importance. Icebergs are at the interface of the land-ice, <span class="hlt">ocean</span>, and sea ice systems, and represent approximately half of the mass flux from the <span class="hlt">Antarctic</span> ice sheet to the <span class="hlt">ocean</span>. Calved icebergs transport freshwater away from the coast and exchange heat with the <span class="hlt">ocean</span>, thereby affecting stratification and circulation, with subsequent indirect thermodynamic effects to the sea ice system. Icebergs also dynamically interact with surrounding sea ice pack, as well as serving as nutrient sources for biogeochemical activity. The spatial pattern of these fluxes transported from the continent to the <span class="hlt">ocean</span> is generally poorly represented in current global climate models. We are implementing an iceberg model into the new Accelerated Climate Model for Energy (ACME) within the MPAS-Seaice model, which uses a variable resolution, unstructured grid framework. This capability will allow for full coupling with the land ice model to inform calving fluxes, and the <span class="hlt">ocean</span> model for freshwater and heat exchange, giving a complete representation of the iceberg lifecycle and increasing the fidelity of ACME <span class="hlt">southern</span> cryosphere simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ARMS...10..503P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ARMS...10..503P"><span>A Synoptic View of the Ventilation and Circulation of <span class="hlt">Antarctic</span> Bottom Water from Chlorofluorocarbons and Natural Tracers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Purkey, Sarah G.; Smethie, William M.; Gebbie, Geoffrey; Gordon, Arnold L.; Sonnerup, Rolf E.; Warner, Mark J.; Bullister, John L.</p> <p>2018-01-01</p> <p><span class="hlt">Antarctic</span> Bottom Water (AABW) is the coldest, densest, most prolific water mass in the global <span class="hlt">ocean</span>. AABW forms at several distinct regions along the <span class="hlt">Antarctic</span> coast and feeds into the bottom limb of the meridional overturning circulation, filling most of the global deep <span class="hlt">ocean</span>. AABW has warmed, freshened, and declined in volume around the globe in recent decades, which has implications for the global heat and sea level rise budgets. Over the past three decades, the use of tracers, especially time-varying tracers such as chlorofluorocarbons, has been essential to our understanding of the formation, circulation, and variability of AABW. Here, we review three decades of temperature, salinity, and tracer data and analysis that have led to our current knowledge of AABW and how the <span class="hlt">southern</span> component of deep-<span class="hlt">ocean</span> ventilation is changing with time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28877009','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28877009"><span>A Synoptic View of the Ventilation and Circulation of <span class="hlt">Antarctic</span> Bottom Water from Chlorofluorocarbons and Natural Tracers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Purkey, Sarah G; Smethie, William M; Gebbie, Geoffrey; Gordon, Arnold L; Sonnerup, Rolf E; Warner, Mark J; Bullister, John L</p> <p>2018-01-03</p> <p><span class="hlt">Antarctic</span> Bottom Water (AABW) is the coldest, densest, most prolific water mass in the global <span class="hlt">ocean</span>. AABW forms at several distinct regions along the <span class="hlt">Antarctic</span> coast and feeds into the bottom limb of the meridional overturning circulation, filling most of the global deep <span class="hlt">ocean</span>. AABW has warmed, freshened, and declined in volume around the globe in recent decades, which has implications for the global heat and sea level rise budgets. Over the past three decades, the use of tracers, especially time-varying tracers such as chlorofluorocarbons, has been essential to our understanding of the formation, circulation, and variability of AABW. Here, we review three decades of temperature, salinity, and tracer data and analysis that have led to our current knowledge of AABW and how the <span class="hlt">southern</span> component of deep-<span class="hlt">ocean</span> ventilation is changing with time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920044190&hterms=marine+biology&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dmarine%2Bbiology','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920044190&hterms=marine+biology&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dmarine%2Bbiology"><span>Ozone depletion - Ultraviolet radiation and phytoplankton biology in <span class="hlt">Antarctic</span> waters</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smith, R. C.; Prezelin, B. B.; Baker, K. S.; Bidigare, R. R.; Boucher, N. P.; Coley, T.; Karentz, D.; Macintyre, S.; Matlick, H. A.; Menzies, D.</p> <p>1992-01-01</p> <p>The near-50-percent thinning of the stratospheric ozone layer over the <span class="hlt">Antarctic</span>, with increased passage of mid-UV radiation to the surface of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, has prompted concern over possible radiation damage to the near-surface phytoplankton communities that are the bases of <span class="hlt">Antarctic</span> marine ecosystems. As the ozone layer thinned, a 6-week study of the marginal ice zone of the Bellingshousen Sea in the austral spring of 1990 noted sea-surface and depth-dependent ratios of mid-UV irradiance to total irradiance increased, and mid-UV inhibition of photosynthesis increased. A 6-12 percent reduction in primary production associated with ozone depletion was estimated to have occurred over the course of the present study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMPP31D1895P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMPP31D1895P"><span><span class="hlt">Southern</span> <span class="hlt">ocean</span> winds during past (and future) warm periods and their affect on Agulhas Leakage and the Atlantic Merdional Overturning Circulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Patel, N. P.; Deconto, R. M.; Condron, A.</p> <p>2013-12-01</p> <p>The leakage of Agulhas Current water into the South Atlantic is now thought to be a major player in global climate change. The volume of Agulhas Leakage is linked to the strength and position of <span class="hlt">southern</span> westerlies. Past changes in the westerly winds over the <span class="hlt">southern</span> <span class="hlt">ocean</span> have been noted on glacial-interglacial timescales, in response to both Northern Hemispheric conditions and more proximal changes in <span class="hlt">Antarctic</span> ice volume. Over recent decades, a southward shift in the <span class="hlt">southern</span> <span class="hlt">ocean</span> westerlies has been observed and is expected to continue with projected climate warming. The resulting increase in Agulhas Leakage is thought to allow more warm, salty water from the Indian <span class="hlt">Ocean</span> into the Atlantic, with the potential to impact the Atlantic Meridional Overturning circulation (AMOC). Some climate models have predicted global warming will result in a slowdown and weakening of the AMOC. A strengthening of the Agulhas Leakage therefore has the potential to counteract that slowdown. Much of the Agulhas leakage is carried in small eddies rotating off the main flow south of Cape Horn. High <span class="hlt">ocean</span> model resolution (< 1/2°) is therefore required to simulate their response to the overlying wind field. However the majority of previous model studies have been too coarse in resolution to quantify the link between the Agulhas Leakage the AMOC. Here we run a series of global high-resolution <span class="hlt">ocean</span> model (1/6°) experiments using the MITgcm to test the effect of a shift in the <span class="hlt">southern</span> hemisphere westerlies on the Agulhas Leakage. A prescribed perturbation of the winds near South Africa shows a significant increase in Agulhas eddies into the Atlantic. Following this, we have conducted longer simulations with the winds over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> perturbed to reflect both past and possible future shifts in the wind field to quantify changes in North Atlantic Deep Water formation and the overall response of the AMOC to this perturbation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.8188C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.8188C"><span>Trends in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Eddy Kinetic Energy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chambers, Don</p> <p>2016-04-01</p> <p>A recent study by Hogg et al. (JGR, 2015) has demonstrated a 20-year trend in eddy kinetic energy (EKE) computed from satellite altimetry data. However, this estimate is based on an averaging over large spatial areas. In this study, we use the same methods to examine regional EKE trends throughout the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, from 1993-2015. We do find significant positive trends in several areas of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, mainly in regions with high mean EKE associated with interactions between jets and bathymetry. At the same time, however, there are also regions with significant negative trends. Overall, EKE in the majority of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> has not changed. These results suggest that the estimates of Hogg et al. may have been biased by these regional extremes, and that more work is needed to quantify climatic changes in EKE.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSPC12B..05C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSPC12B..05C"><span>Trends in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Eddy Kinetic Energy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chambers, D. P.</p> <p>2016-02-01</p> <p>A recent study by Hogg et al. (JGR, 2015) has demonstrated a 20-year trend in eddy kinetic energy (EKE) computed from satellite altimetry data. However, this estimate is based on an averaging over large spatial areas. In this study, we use the same methods to examine regional EKE trends throughout the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, from 1993-2015. We do find significant positive trends in several areas of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, mainly in regions with high mean EKE associated with interactions between jets and bathymetry. At the same time, however, there are also regions with significant negative trends. Overall, EKE in the majority of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> has not changed. These results suggest that the estimates of Hogg et al. may have been biased by these regional extremes, and that more work is needed to quantify climatic changes in EKE.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.2354M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.2354M"><span>Coherency Between Volume Transport in the <span class="hlt">Antarctic</span> Circumpolar Current and <span class="hlt">Southern</span> Hemisphere Winds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Makowski, Jessica; Chambers, Don; Bonin, Jennifer</p> <p>2013-04-01</p> <p>Previous studies have suggested that <span class="hlt">ocean</span> bottom pressure (OBP) can be used to measure the transport variability of the <span class="hlt">Antarctic</span> Circumpolar Current (ACC). The OBP observations from the Gravity Recovery and Climate Experiment (GRACE) will be used to calculate transport along the 150°E longitude choke point, between Antarctica and Australia. We will examine whether zonally averaged wind stress, wind stress curl, or local zonal winds are more coherent with zonal mass transport variability. Preliminary studies suggest that seasonal variation in transport across 150°E is more correlated with winds along and north of the northern front of the ACC: the Sub Tropical front (STF). It also appears that interannual variations in transport along 150°E are related to wind variations south of the STF and centered south of the Sub <span class="hlt">Antarctic</span> Front (SAF). We have observed a strong anti-correlation across the SAF, in the Indian <span class="hlt">Ocean</span>, which suggests wind stress curl may also be responsible for transport variations. Preliminary results will be presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940011207','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940011207"><span>Exploring the <span class="hlt">southern</span> <span class="hlt">ocean</span> response to climate change</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Martinson, Douglas G.; Rind, David; Parkinson, Claire</p> <p>1993-01-01</p> <p>The purpose of this project was to couple a regional (<span class="hlt">Southern</span> <span class="hlt">Ocean</span>) <span class="hlt">ocean</span>/sea ice model to the existing Goddard Institute for Space Science (GISS) atmospheric general circulation model (GCM). This modification recognizes: the relative isolation of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>; the need to account, prognostically, for the significant air/sea/ice interaction through all involved components; and the advantage of translating the atmospheric lower boundary (typically the rapidly changing <span class="hlt">ocean</span> surface) to a level that is consistent with the physical response times governing the system evolution (that is, to the base of the fast responding <span class="hlt">ocean</span> surface layer). The deeper <span class="hlt">ocean</span> beneath this layer varies on time scales several orders of magnitude slower than the atmosphere and surface <span class="hlt">ocean</span>, and therefore the boundary between the upper and deep <span class="hlt">ocean</span> represents a more reasonable fixed boundary condition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007DSRII..54..601L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007DSRII..54..601L"><span>High biomass, low export regimes in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lam, Phoebe J.; Bishop, James K. B.</p> <p>2007-03-01</p> <p>This paper investigates ballasting and remineralization controls of carbon sedimentation in the Twilight Zone (100-1000 m) of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Size-fractionated (<1 μm, 1-51 μm, >51 μm) suspended particulate matter was collected by large-volume in-situ filtration from the upper 1000 m in the Subantarctic (55°S, 172°W) and <span class="hlt">Antarctic</span> (66°S, 172°W) zones of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> during the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Iron Experiment (SOFeX) in January-February 2002. Particles were analyzed for major chemical constituents (POC, P, biogenic Si, CaCO 3), and digital and SEM image analyses of particles were used to aid in the interpretation of the chemical profiles. Twilight Zone waters at 66°S in the <span class="hlt">Antarctic</span> had a steeper decrease in POC with depth than at 55°S in the Subantarctic, with lower POC concentrations in all size fractions at 66°S than at 55°S, despite up to an-order-of magnitude higher POC in surface waters at 66°S. The decay length scale of >51-μm POC was significantly shorter in the upper Twilight Zone at 66°S ( δe=26 m) compared to 55°S ( δe=81 m). Particles in the carbonate-producing 55°S did not have higher excess densities than particles from the diatom-dominated 66°S, indicating that there was no direct ballast effect that accounted for deeper POC penetration at 55°S. An indirect ballast effect due to differences in particle packaging and porosities cannot be ruled out, however, as aggregate porosities were high (˜97%) and variable. Image analyses point to the importance of particle loss rates from zooplankton grazing and remineralization as determining factors for the difference in Twilight Zone POC concentrations at 55°S and 66°S, with stronger and more focused shallow remineralization at 66°S. At 66°S, an abundance of large (several mm long) fecal pellets from the surface to 150 m, and almost total removal of large aggregates by 200 m, reflected the actions of a single or few zooplankton species capable of grazing diatoms in the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20070016598&hterms=sea+ice+albedo&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dsea%2Bice%2Balbedo','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20070016598&hterms=sea+ice+albedo&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dsea%2Bice%2Balbedo"><span>Observational Evidence of a Hemispheric-wide Ice-<span class="hlt">ocean</span> Albedo Feedback Effect on <span class="hlt">Antarctic</span> Sea-ice Decay</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nihashi, Sohey; Cavalieri, Donald J.</p> <p>2007-01-01</p> <p>The effect of ice-<span class="hlt">ocean</span> albedo feedback (a kind of ice-albedo feedback) on sea-ice decay is demonstrated over the <span class="hlt">Antarctic</span> sea-ice zone from an analysis of satellite-derived hemispheric sea ice concentration and European Centre for Medium-Range Weather Forecasts (ERA-40) atmospheric data for the period 1979-2001. Sea ice concentration in December (time of most active melt) correlates better with the meridional component of the wind-forced ice drift (MID) in November (beginning of the melt season) than the MID in December. This 1 month lagged correlation is observed in most of the <span class="hlt">Antarctic</span> sea-ice covered <span class="hlt">ocean</span>. Daily time series of ice , concentration show that the ice concentration anomaly increases toward the time of maximum sea-ice melt. These findings can be explained by the following positive feedback effect: once ice concentration decreases (increases) at the beginning of the melt season, solar heating of the upper <span class="hlt">ocean</span> through the increased (decreased) open water fraction is enhanced (reduced), leading to (suppressing) a further decrease in ice concentration by the <span class="hlt">oceanic</span> heat. Results obtained fi-om a simple ice-<span class="hlt">ocean</span> coupled model also support our interpretation of the observational results. This positive feedback mechanism explains in part the large interannual variability of the sea-ice cover in summer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1815826M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1815826M"><span>Evaluating <span class="hlt">Antarctic</span> sea ice predictability at seasonal to interannual timescales in global climate models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marchi, Sylvain; Fichefet, Thierry; Goosse, Hugues; Zunz, Violette; Tietsche, Steffen; Day, Jonny; Hawkins, Ed</p> <p>2016-04-01</p> <p>Unlike the rapid sea ice losses reported in the Arctic, satellite observations show an overall increase in <span class="hlt">Antarctic</span> sea ice extent over recent decades. Although many processes have already been suggested to explain this positive trend, it remains the subject of current investigations. Understanding the evolution of the <span class="hlt">Antarctic</span> sea ice turns out to be more complicated than for the Arctic for two reasons: the lack of observations and the well-known biases of climate models in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Irrespective of those issues, another one is to determine whether the positive trend in sea ice extent would have been predictable if adequate observations and models were available some decades ago. This study of <span class="hlt">Antarctic</span> sea ice predictability is carried out using 6 global climate models (HadGEM1.2, MPI-ESM-LR, GFDL CM3, EC-Earth V2, MIROC 5.2 and ECHAM 6-FESOM) which are all part of the APPOSITE project. These models are used to perform hindcast simulations in a perfect model approach. The predictive skill is estimated thanks to the PPP (Potential Prognostic Predictability) and the ACC (Anomaly Correlation Coefficient). The former is a measure of the uncertainty of the ensemble while the latter assesses the accuracy of the prediction. These two indicators are applied to different variables related to sea ice, in particular the total sea ice extent and the ice edge location. This first model intercomparison study about sea ice predictability in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> aims at giving a general overview of <span class="hlt">Antarctic</span> sea ice predictability in current global climate models.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1915443S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1915443S"><span>Centennial-millennial scale variations in Western <span class="hlt">Antarctic</span> Ice Sheet discharge and their relationship to climate and <span class="hlt">ocean</span> changes during the late Holocene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Snilstveit Hoem, Frida; Ninnemann, Ulysses S.; Kleiven, Helga (Kikki) F.; Irvali, Nil</p> <p>2017-04-01</p> <p>The Western <span class="hlt">Antarctic</span> Ice Sheet (WAIS) may be highly sensitive to future warming and to <span class="hlt">ocean</span> driven changes in subsurface melting. Understanding this sensitivity is critical as WAIS dynamics are a major source of uncertainty in sea level rise and regional climate projections. Although there is increasing evidence that WAIS discharge has varied on centennial to multi-millennial timescales since the last glacial period much less is known about its most recent (late Holocene) behavior. This period is particularly important as a baseline for delineating natural and anthropogenic influences and understanding potential coupling between climate, <span class="hlt">ocean</span> circulation, and WAIS discharge. Here we present high-resolution records of WAIS discharge together with co-registered signals of surface and deep <span class="hlt">ocean</span> physical property changes in a multicore taken from the <span class="hlt">southern</span> flank of the North Scotia Sea Ridge (53˚ 31.813 S; 44˚ 42.143 W at 2750m water depth) spanning the past 4000 years. The site is situated just south/east of the polar front beyond the reach of seasonal sea ice and its potentially confounding influence on the ice-rafted debris (IRD) signal but still influenced by icebergs mostly originating from the WAIS. Our record of IRD from core GS08-151-02MC provides a centennially resolved record of iceberg supply from which we infer <span class="hlt">Antarctic</span> ice-sheet dynamics and variability, while we use the oxygen and carbon isotopic composition of benthic (U. peregrina) and planktonic (N. pachyderma (s)) foraminifera to give (regional) information on past polar deep water and surface water temperatures, circulation and nutrients. Our results show higher amount of IRD between 4200-1800 cal yr B.P. This is in agreement with paleoclimate records reconstructing the onset of the neoglacial, sea ice expansion at about 5000 cal yr B.P. in the Atlantic sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, and glaciers advancing in South America. The strongest IRD peak of the past millennium, which is otherwise a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.C21C0710W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.C21C0710W"><span>Observations of upper <span class="hlt">ocean</span> stability and heat fluxes in the <span class="hlt">Antarctic</span> from under-ice Argo float profile data.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wilson, E. A.; Riser, S.</p> <p>2016-12-01</p> <p>Sea ice growth around Antarctica is intimately linked to the stability and thermohaline structure of the underlying <span class="hlt">ocean</span>. As sea ice grows, the resulting brine triggers convective instabilities that deepen the mixed layer and entrain warm water from the weakly stratified pycnocline. The heat released from this process acts as a strong negative feedback to ice growth which, under the right scenarios, can exceed the initial atmospheric heat loss. Much of our current understanding of this ice-<span class="hlt">ocean</span> interaction comes from a handful of relatively short field campaigns in the Weddell Sea. Here, we supplement those observations with an analysis of over 9000 under-ice Argo float profiles, collected between 2006-2015. These profiles provide an unprecedented view of the temporal and spatial variability of the upper <span class="hlt">ocean</span> structure throughout the <span class="hlt">Antarctic</span> region. With these observations and a theoretical understanding of the coupled ice-<span class="hlt">ocean</span> system, we assess the <span class="hlt">ocean</span>'s potential to limit thermodynamic ice growth as well as its susceptibility to deep convection in different regions. Using these results, we infer how recent climatic changes may influence <span class="hlt">Antarctic</span> sea ice growth and deep <span class="hlt">ocean</span> ventilation in the near future.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMGC33A0498N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMGC33A0498N"><span>High-resolution coupled ice sheet-<span class="hlt">ocean</span> modeling using the POPSICLES model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ng, E. G.; Martin, D. F.; Asay-Davis, X.; Price, S. F.; Collins, W.</p> <p>2014-12-01</p> <p>It is expected that a primary driver of future change of the <span class="hlt">Antarctic</span> ice sheet will be changes in submarine melting driven by incursions of warm <span class="hlt">ocean</span> water into sub-ice shelf cavities. Correctly modeling this response on a continental scale will require high-resolution modeling of the coupled ice-<span class="hlt">ocean</span> system. We describe the computational and modeling challenges in our simulations of the full <span class="hlt">Southern</span> <span class="hlt">Ocean</span> coupled to a continental-scale <span class="hlt">Antarctic</span> ice sheet model at unprecedented spatial resolutions (0.1 degree for the <span class="hlt">ocean</span> model and adaptive mesh refinement down to 500m in the ice sheet model). The POPSICLES model couples the POP2x <span class="hlt">ocean</span> model, a modified version of the Parallel <span class="hlt">Ocean</span> Program (Smith and Gent, 2002), with the BISICLES ice-sheet model (Cornford et al., 2012) using a synchronous offline-coupling scheme. Part of the PISCEES SciDAC project and built on the Chombo framework, BISICLES makes use of adaptive mesh refinement to fully resolve dynamically-important regions like grounding lines and employs a momentum balance similar to the vertically-integrated formulation of Schoof and Hindmarsh (2009). Results of BISICLES simulations have compared favorably to comparable simulations with a Stokes momentum balance in both idealized tests like MISMIP3D (Pattyn et al., 2013) and realistic configurations (Favier et al. 2014). POP2x includes sub-ice-shelf circulation using partial top cells (Losch, 2008) and boundary layer physics following Holland and Jenkins (1999), Jenkins (2001), and Jenkins et al. (2010). Standalone POP2x output compares well with standard ice-<span class="hlt">ocean</span> test cases (e.g., ISOMIP; Losch, 2008) and other continental-scale simulations and melt-rate observations (Kimura et al., 2013; Rignot et al., 2013). For the POPSICLES <span class="hlt">Antarctic-Southern</span> <span class="hlt">Ocean</span> simulations, ice sheet and <span class="hlt">ocean</span> models communicate at one-month coupling intervals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22174131','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22174131"><span>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span>'s role in carbon exchange during the last deglaciation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Burke, Andrea; Robinson, Laura F</p> <p>2012-02-03</p> <p>Changes in the upwelling and degassing of carbon from the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> form one of the leading hypotheses for the cause of glacial-interglacial changes in atmospheric carbon dioxide. We present a 25,000-year-long <span class="hlt">Southern</span> <span class="hlt">Ocean</span> radiocarbon record reconstructed from deep-sea corals, which shows radiocarbon-depleted waters during the glacial period and through the early deglaciation. This depletion and associated deep stratification disappeared by ~14.6 ka (thousand years ago), consistent with the transfer of carbon from the deep <span class="hlt">ocean</span> to the surface <span class="hlt">ocean</span> and atmosphere via a <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ventilation event. Given this evidence for carbon exchange in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, we show that existing deep-<span class="hlt">ocean</span> radiocarbon records from the glacial period are sufficiently depleted to explain the ~190 per mil drop in atmospheric radiocarbon between ~17 and 14.5 ka.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010NatGe...3..273S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010NatGe...3..273S"><span>Zonally asymmetric response of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> mixed-layer depth to the <span class="hlt">Southern</span> Annular Mode</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sallée, J. B.; Speer, K. G.; Rintoul, S. R.</p> <p>2010-04-01</p> <p>Interactions between the atmosphere and <span class="hlt">ocean</span> are mediated by the mixed layer at the <span class="hlt">ocean</span> surface. The depth of this layer is determined by wind forcing and heating from the atmosphere. Variations in mixed-layer depth affect the rate of exchange between the atmosphere and deeper <span class="hlt">ocean</span>, the capacity of the <span class="hlt">ocean</span> to store heat and carbon and the availability of light and nutrients to support the growth of phytoplankton. However, the response of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> mixed layer to changes in the atmosphere is not well known. Here we analyse temperature and salinity data from Argo profiling floats to show that the <span class="hlt">Southern</span> Annular Mode (SAM), the dominant mode of atmospheric variability in the <span class="hlt">Southern</span> Hemisphere, leads to large-scale anomalies in mixed-layer depth that are zonally asymmetric. From a simple heat budget of the mixed layer we conclude that meridional winds associated with departures of the SAM from zonal symmetry cause anomalies in heat flux that can, in turn, explain the observed changes of mixed-layer depth and sea surface temperature. Our results suggest that changes in the SAM, including recent and projected trends attributed to human activity, drive variations in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> mixed-layer depth, with consequences for air-sea exchange, <span class="hlt">ocean</span> sequestration of heat and carbon, and biological productivity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRC..120.4245M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRC..120.4245M"><span>Using <span class="hlt">ocean</span> bottom pressure from the gravity recovery and climate experiment (GRACE) to estimate transport variability in the <span class="hlt">southern</span> Indian <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Makowski, Jessica K.; Chambers, Don P.; Bonin, Jennifer A.</p> <p>2015-06-01</p> <p>Previous studies have suggested that <span class="hlt">ocean</span> bottom pressure (OBP) from the Gravity Recovery and Climate Experiment (GRACE) can be used to measure the depth-averaged, or barotropic, transport variability of the <span class="hlt">Antarctic</span> Circumpolar Current (ACC). Here, we use GRACE OBP observations to calculate transport variability in a region of the <span class="hlt">southern</span> Indian <span class="hlt">Ocean</span> encompassing the major fronts of the ACC. We use a statistical analysis of a simulated GRACE-like data set to determine the uncertainty of the estimated transport for the 2003.0-2013.0 time period. We find that when the transport is averaged over 60° of longitude, the uncertainty (one standard error) is close to 1 Sv (1 Sv = 106 m3 s-1) for low-pass filtered transport, which is significantly smaller than the signal and lower than previous studies have found. The interannual variability is correlated with the <span class="hlt">Southern</span> Annual mode (SAM) (0.61), but more highly correlated with circumpolar zonally averaged winds between 45°S and 65°S (0.88). GRACE transport reflects significant changes in transport between 2007 and 2009 that is observed in the zonal wind variations but not in the SAM index. We also find a statistically significant trend in transport (-1.0 ± 0.4 Sv yr-1, 90% confidence) that is correlated with a local deceleration in zonal winds related to an asymmetry in the SAM on multidecadal periods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3295276','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3295276"><span>Ancient climate change, antifreeze, and the evolutionary diversification of <span class="hlt">Antarctic</span> fishes</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Near, Thomas J.; Dornburg, Alex; Kuhn, Kristen L.; Eastman, Joseph T.; Pennington, Jillian N.; Patarnello, Tomaso; Zane, Lorenzo; Fernández, Daniel A.; Jones, Christopher D.</p> <p>2012-01-01</p> <p>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> around Antarctica is among the most rapidly warming regions on Earth, but has experienced episodic climate change during the past 40 million years. It remains unclear how ancient periods of climate change have shaped <span class="hlt">Antarctic</span> biodiversity. The origin of antifreeze glycoproteins (AFGPs) in <span class="hlt">Antarctic</span> notothenioid fishes has become a classic example of how the evolution of a key innovation in response to climate change can drive adaptive radiation. By using a time-calibrated molecular phylogeny of notothenioids and reconstructed paleoclimate, we demonstrate that the origin of AFGP occurred between 42 and 22 Ma, which includes a period of global cooling approximately 35 Ma. However, the most species-rich lineages diversified and evolved significant ecological differences at least 10 million years after the origin of AFGPs, during a second cooling event in the Late Miocene (11.6–5.3 Ma). This pattern indicates that AFGP was not the sole trigger of the notothenioid adaptive radiation. Instead, the bulk of the species richness and ecological diversity originated during the Late Miocene and into the Early Pliocene, a time coincident with the origin of polar conditions and increased ice activity in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Our results challenge the current understanding of the evolution of <span class="hlt">Antarctic</span> notothenioids suggesting that the ecological opportunity that underlies this adaptive radiation is not linked to a single trait, but rather to a combination of freeze avoidance offered by AFGPs and subsequent exploitation of new habitats and open niches created by increased glacial and ice sheet activity. PMID:22331888</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4032509','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4032509"><span>The <span class="hlt">ocean</span>'s role in polar climate change: asymmetric Arctic and <span class="hlt">Antarctic</span> responses to greenhouse gas and ozone forcing</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Marshall, John; Armour, Kyle C.; Scott, Jeffery R.; Kostov, Yavor; Hausmann, Ute; Ferreira, David; Shepherd, Theodore G.; Bitz, Cecilia M.</p> <p>2014-01-01</p> <p>In recent decades, the Arctic has been warming and sea ice disappearing. By contrast, the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> around Antarctica has been (mainly) cooling and sea-ice extent growing. We argue here that interhemispheric asymmetries in the mean <span class="hlt">ocean</span> circulation, with sinking in the northern North Atlantic and upwelling around Antarctica, strongly influence the sea-surface temperature (SST) response to anthropogenic greenhouse gas (GHG) forcing, accelerating warming in the Arctic while delaying it in the <span class="hlt">Antarctic</span>. Furthermore, while the amplitude of GHG forcing has been similar at the poles, significant ozone depletion only occurs over Antarctica. We suggest that the initial response of SST around Antarctica to ozone depletion is one of cooling and only later adds to the GHG-induced warming trend as upwelling of sub-surface warm water associated with stronger surface westerlies impacts surface properties. We organize our discussion around ‘climate response functions’ (CRFs), i.e. the response of the climate to ‘step’ changes in anthropogenic forcing in which GHG and/or ozone-hole forcing is abruptly turned on and the transient response of the climate revealed and studied. Convolutions of known or postulated GHG and ozone-hole forcing functions with their respective CRFs then yield the transient forced SST response (implied by linear response theory), providing a context for discussion of the differing warming/cooling trends in the Arctic and <span class="hlt">Antarctic</span>. We speculate that the period through which we are now passing may be one in which the delayed warming of SST associated with GHG forcing around Antarctica is largely cancelled by the cooling effects associated with the ozone hole. By mid-century, however, ozone-hole effects may instead be adding to GHG warming around Antarctica but with diminished amplitude as the ozone hole heals. The Arctic, meanwhile, responding to GHG forcing but in a manner amplified by <span class="hlt">ocean</span> heat transport, may continue to warm at an</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24891392','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24891392"><span>The <span class="hlt">ocean</span>'s role in polar climate change: asymmetric Arctic and <span class="hlt">Antarctic</span> responses to greenhouse gas and ozone forcing.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Marshall, John; Armour, Kyle C; Scott, Jeffery R; Kostov, Yavor; Hausmann, Ute; Ferreira, David; Shepherd, Theodore G; Bitz, Cecilia M</p> <p>2014-07-13</p> <p>In recent decades, the Arctic has been warming and sea ice disappearing. By contrast, the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> around Antarctica has been (mainly) cooling and sea-ice extent growing. We argue here that interhemispheric asymmetries in the mean <span class="hlt">ocean</span> circulation, with sinking in the northern North Atlantic and upwelling around Antarctica, strongly influence the sea-surface temperature (SST) response to anthropogenic greenhouse gas (GHG) forcing, accelerating warming in the Arctic while delaying it in the <span class="hlt">Antarctic</span>. Furthermore, while the amplitude of GHG forcing has been similar at the poles, significant ozone depletion only occurs over Antarctica. We suggest that the initial response of SST around Antarctica to ozone depletion is one of cooling and only later adds to the GHG-induced warming trend as upwelling of sub-surface warm water associated with stronger surface westerlies impacts surface properties. We organize our discussion around 'climate response functions' (CRFs), i.e. the response of the climate to 'step' changes in anthropogenic forcing in which GHG and/or ozone-hole forcing is abruptly turned on and the transient response of the climate revealed and studied. Convolutions of known or postulated GHG and ozone-hole forcing functions with their respective CRFs then yield the transient forced SST response (implied by linear response theory), providing a context for discussion of the differing warming/cooling trends in the Arctic and <span class="hlt">Antarctic</span>. We speculate that the period through which we are now passing may be one in which the delayed warming of SST associated with GHG forcing around Antarctica is largely cancelled by the cooling effects associated with the ozone hole. By mid-century, however, ozone-hole effects may instead be adding to GHG warming around Antarctica but with diminished amplitude as the ozone hole heals. The Arctic, meanwhile, responding to GHG forcing but in a manner amplified by <span class="hlt">ocean</span> heat transport, may continue to warm at an accelerating rate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4778439','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4778439"><span><span class="hlt">Ocean</span> acidification exerts negative effects during warming conditions in a developing <span class="hlt">Antarctic</span> fish</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Flynn, Erin E; Bjelde, Brittany E; Miller, Nathan A</p> <p>2015-01-01</p> <p>Abstract Anthropogenic CO2 is rapidly causing <span class="hlt">oceans</span> to become warmer and more acidic, challenging marine ectotherms to respond to simultaneous changes in their environment. While recent work has highlighted that marine fishes, particularly during early development, can be vulnerable to <span class="hlt">ocean</span> acidification, we lack an understanding of how life-history strategies, ecosystems and concurrent <span class="hlt">ocean</span> warming interplay with interspecific susceptibility. To address the effects of multiple <span class="hlt">ocean</span> changes on cold-adapted, slowly developing fishes, we investigated the interactive effects of elevated partial pressure of carbon dioxide (pCO2) and temperature on the embryonic physiology of an <span class="hlt">Antarctic</span> dragonfish (Gymnodraco acuticeps), with protracted embryogenesis (∼10 months). Using an integrative, experimental approach, our research examined the impacts of near-future warming [−1 (ambient) and 2°C (+3°C)] and <span class="hlt">ocean</span> acidification [420 (ambient), 650 (moderate) and 1000 μatm pCO2 (high)] on survival, development and metabolic processes over the course of 3 weeks in early development. In the presence of increased pCO2 alone, embryonic mortality did not increase, with greatest overall survival at the highest pCO2. Furthermore, embryos were significantly more likely to be at a later developmental stage at high pCO2 by 3 weeks relative to ambient pCO2. However, in combined warming and <span class="hlt">ocean</span> acidification scenarios, dragonfish embryos experienced a dose-dependent, synergistic decrease in survival and developed more slowly. We also found significant interactions between temperature, pCO2 and time in aerobic enzyme activity (citrate synthase). Increased temperature alone increased whole-organism metabolic rate (O2 consumption) and developmental rate and slightly decreased osmolality at the cost of increased mortality. Our findings suggest that developing dragonfish are more sensitive to <span class="hlt">ocean</span> warming and may experience negative physiological effects of <span class="hlt">ocean</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27293718','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27293718"><span><span class="hlt">Ocean</span> acidification exerts negative effects during warming conditions in a developing <span class="hlt">Antarctic</span> fish.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Flynn, Erin E; Bjelde, Brittany E; Miller, Nathan A; Todgham, Anne E</p> <p>2015-01-01</p> <p>Anthropogenic CO2 is rapidly causing <span class="hlt">oceans</span> to become warmer and more acidic, challenging marine ectotherms to respond to simultaneous changes in their environment. While recent work has highlighted that marine fishes, particularly during early development, can be vulnerable to <span class="hlt">ocean</span> acidification, we lack an understanding of how life-history strategies, ecosystems and concurrent <span class="hlt">ocean</span> warming interplay with interspecific susceptibility. To address the effects of multiple <span class="hlt">ocean</span> changes on cold-adapted, slowly developing fishes, we investigated the interactive effects of elevated partial pressure of carbon dioxide (pCO2) and temperature on the embryonic physiology of an <span class="hlt">Antarctic</span> dragonfish (Gymnodraco acuticeps), with protracted embryogenesis (∼10 months). Using an integrative, experimental approach, our research examined the impacts of near-future warming [-1 (ambient) and 2°C (+3°C)] and <span class="hlt">ocean</span> acidification [420 (ambient), 650 (moderate) and 1000 μatm pCO2 (high)] on survival, development and metabolic processes over the course of 3 weeks in early development. In the presence of increased pCO2 alone, embryonic mortality did not increase, with greatest overall survival at the highest pCO2. Furthermore, embryos were significantly more likely to be at a later developmental stage at high pCO2 by 3 weeks relative to ambient pCO2. However, in combined warming and <span class="hlt">ocean</span> acidification scenarios, dragonfish embryos experienced a dose-dependent, synergistic decrease in survival and developed more slowly. We also found significant interactions between temperature, pCO2 and time in aerobic enzyme activity (citrate synthase). Increased temperature alone increased whole-organism metabolic rate (O2 consumption) and developmental rate and slightly decreased osmolality at the cost of increased mortality. Our findings suggest that developing dragonfish are more sensitive to <span class="hlt">ocean</span> warming and may experience negative physiological effects of <span class="hlt">ocean</span> acidification only in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25753990','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25753990"><span>Bacterial community dynamics during polysaccharide degradation at contrasting sites in the <span class="hlt">Southern</span> and Atlantic <span class="hlt">Oceans</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wietz, Matthias; Wemheuer, Bernd; Simon, Heike; Giebel, Helge-Ansgar; Seibt, Maren A; Daniel, Rolf; Brinkhoff, Thorsten; Simon, Meinhard</p> <p>2015-10-01</p> <p>The bacterial degradation of polysaccharides is central to marine carbon cycling, but little is known about the bacterial taxa that degrade specific marine polysaccharides. Here, bacterial growth and community dynamics were studied during the degradation of the polysaccharides chitin, alginate and agarose in microcosm experiments at four contrasting locations in the <span class="hlt">Southern</span> and Atlantic <span class="hlt">Oceans</span>. At the <span class="hlt">Southern</span> polar front, chitin-supplemented microcosms were characterized by higher fractions of actively growing cells and a community shift from Alphaproteobacteria to Gammaproteobacteria and Bacteroidetes. At the <span class="hlt">Antarctic</span> ice shelf, chitin degradation was associated with growth of Bacteroidetes, with 24% higher cell numbers compared with the control. At the Patagonian continental shelf, alginate and agarose degradation covaried with growth of different Alteromonadaceae populations, each with specific temporal growth patterns. At the Mauritanian upwelling, only the alginate hydrolysis product guluronate was consumed, coincident with increasing abundances of Alteromonadaceae and possibly cross-feeding SAR11. 16S rRNA gene amplicon libraries indicated that growth of the Bacteroidetes-affiliated genus Reichenbachiella was stimulated by chitin at all cold and temperate water stations, suggesting comparable ecological roles over wide geographical scales. Overall, the predominance of location-specific patterns showed that bacterial communities from contrasting <span class="hlt">oceanic</span> biomes have members with different potentials to hydrolyse polysaccharides. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JARS...11a6019M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JARS...11a6019M"><span>Shifting of phytoplankton community in the frontal regions of Indian <span class="hlt">Ocean</span> sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> using in situ and satellite data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mishra, Rajani Kanta; Jena, Babula; Anilkumar, Narayana Pillai; Sinha, Rupesh Kumar</p> <p>2017-01-01</p> <p>The phytoplankton pigment indices were used to characterize the spatial succession of the community composition in the frontal regions of the subtropical front (STF), sub-<span class="hlt">Antarctic</span> front (SAF), and polar front (PF) in the Indian <span class="hlt">Ocean</span> sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> during austral summer 2013. Diagnostic indices revealed that the flagellates were dominant in STF (51%) and progressively declined toward SAF (39%) and PF (11%). Similarly, the prokaryotes were highest in STF (43%) and decreased to SAF (32%) and PF (28%). In contrast, the diatoms were gradually increased from STF (6%) to SAF (29%) and PF (61%). The variability of flagellates and diatoms from the STF to PF is attributed to the variability of photosynthetically available radiation, sea surface temperature, and sea surface wind speed. The in-situ pigment indices were then compared to the NASA <span class="hlt">Ocean</span> Biogeochemical model that shows the similar patterns of frontal community distribution except their magnitude. Similarly, the satellite retrieved phytoplankton biomass (chlorophyll a) was checked for its consistency after comparing with the in-situ observations and the result shows underestimation of satellite measured values. The result suggests that the conjunctive analysis of in-situ, satellite, and model archive is suitable to study the impact of climate variability on the structure of marine ecosystems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3459913','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3459913"><span>Effects of Late-Cenozoic Glaciation on Habitat Availability in <span class="hlt">Antarctic</span> Benthic Shrimps (Crustacea: Decapoda: Caridea)</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dambach, Johannes; Thatje, Sven; Rödder, Dennis; Basher, Zeenatul; Raupach, Michael J.</p> <p>2012-01-01</p> <p>Marine invertebrates inhabiting the high <span class="hlt">Antarctic</span> continental shelves are challenged by disturbance of the seafloor by grounded ice, low but stable water temperatures and variable food availability in response to seasonal sea-ice cover. Though a high diversity of life has successfully adapted to such conditions, it is generally agreed that during the Last Glacial Maximum (LGM) the large-scale cover of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> by multi-annual sea ice and the advance of the continental ice sheets across the shelf faced life with conditions, exceeding those seen today by an order of magnitude. Conditions prevailing at the LGM may have therefore acted as a bottleneck event to both the ecology as well as genetic diversity of today's fauna. Here, we use for the first time specific Species Distribution Models (SDMs) for marine arthropods of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> to assess effects of habitat contraction during the LGM on the three most common benthic caridean shrimp species that exhibit a strong depth zonation on the <span class="hlt">Antarctic</span> continental shelf. While the shallow-water species Chorismus antarcticus and Notocrangon antarcticus were limited to a drastically reduced habitat during the LGM, the deep-water shrimp Nematocarcinus lanceopes found refuge in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> deep sea. The modeling results are in accordance with genetic diversity patterns available for C. antarcticus and N. lanceopes and support the hypothesis that habitat contraction at the LGM resulted in a loss of genetic diversity in shallow water benthos. PMID:23029463</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23029463','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23029463"><span>Effects of late-cenozoic glaciation on habitat availability in <span class="hlt">Antarctic</span> benthic shrimps (Crustacea: Decapoda: Caridea).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dambach, Johannes; Thatje, Sven; Rödder, Dennis; Basher, Zeenatul; Raupach, Michael J</p> <p>2012-01-01</p> <p>Marine invertebrates inhabiting the high <span class="hlt">Antarctic</span> continental shelves are challenged by disturbance of the seafloor by grounded ice, low but stable water temperatures and variable food availability in response to seasonal sea-ice cover. Though a high diversity of life has successfully adapted to such conditions, it is generally agreed that during the Last Glacial Maximum (LGM) the large-scale cover of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> by multi-annual sea ice and the advance of the continental ice sheets across the shelf faced life with conditions, exceeding those seen today by an order of magnitude. Conditions prevailing at the LGM may have therefore acted as a bottleneck event to both the ecology as well as genetic diversity of today's fauna. Here, we use for the first time specific Species Distribution Models (SDMs) for marine arthropods of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> to assess effects of habitat contraction during the LGM on the three most common benthic caridean shrimp species that exhibit a strong depth zonation on the <span class="hlt">Antarctic</span> continental shelf. While the shallow-water species Chorismus antarcticus and Notocrangon antarcticus were limited to a drastically reduced habitat during the LGM, the deep-water shrimp Nematocarcinus lanceopes found refuge in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> deep sea. The modeling results are in accordance with genetic diversity patterns available for C. antarcticus and N. lanceopes and support the hypothesis that habitat contraction at the LGM resulted in a loss of genetic diversity in shallow water benthos.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMPA32A..08R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMPA32A..08R"><span>Reaching for the Horizon: Enabling 21st Century <span class="hlt">Antarctic</span> Science</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rogan-Finnemore, M.; Kennicutt, M. C., II; Kim, Y.</p> <p>2015-12-01</p> <p>The Council of Managers of National <span class="hlt">Antarctic</span> Programs' (COMNAP) <span class="hlt">Antarctic</span> Roadmap Challenges(ARC) project translated the 80 highest priority <span class="hlt">Antarctic</span> and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> scientific questionsidentified by the community via the SCAR <span class="hlt">Antarctic</span> Science Horizon Scan into the highest prioritytechnological, access, infrastructure and logistics needs to enable the necessary research to answer thequestions. A workshop assembled expert and experienced <span class="hlt">Antarctic</span> scientists and National <span class="hlt">Antarctic</span>Program operators from around the globe to discern the highest priority technological needs includingthe current status of development and availability, where the technologies will be utilized in the <span class="hlt">Antarctic</span> area, at what temporal scales and frequencies the technologies will be employed,and how broadly applicable the technologies are for answering the highest priority scientific questions.Secondly the logistics, access, and infrastructure requirements were defined that are necessary todeliver the science in terms of feasibility including cost and benefit as determined by expected scientific return on investment. Finally, based on consideration of the science objectives and the mix oftechnologies implications for configuring National <span class="hlt">Antarctic</span> Program logistics capabilities andinfrastructure architecture over the next 20 years were determined. In particular those elements thatwere either of a complexity, requiring long term investments to achieve and/or having an associated cost that realistically can only (or best) be achieved by international coordination, planning and partnerships were identified. Major trends (changes) in logistics, access, and infrastructure requirements were identified that allow for long-term strategic alignment of international capabilities, resources and capacity. The outcomes of this project will be reported.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/7264152-possible-impacts-ozone-depletion-trophic-interactions-biogenic-vertical-carbon-flux-southern-ocean','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/7264152-possible-impacts-ozone-depletion-trophic-interactions-biogenic-vertical-carbon-flux-southern-ocean"><span>Possible impacts of ozone depletion on trophic interactions and biogenic vertical carbon flux in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Marchant, H.J.; Davidson, A.</p> <p>1992-03-01</p> <p>Among the most productive region of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is the marginal ice edge zone that trails the retreating ice edge in spring and early summer. The timing of this near-surface phytoplankton bloom coincides with seasonal stratospheric ozone depletion when UV irradiance is reportedly as high as in mid-summer. Recent investigations indicate that <span class="hlt">antarctic</span> marine phytoplankton are presently UV stressed. The extent to which increasing UV radiation diminishes the ability of phytoplankton to fix C02 and/or leads to changes in their species composition is equivocal. The colonial stage in the life cycle of the alga Phaeocystis pouchetii is one ofmore » the major components of the bloom. The authors have found that this alga produces extracellular products which are strongly UV-B absorbing. When exposed to increasing levels of UV-B radiation, survival of <span class="hlt">antarctic</span> colonial Phaeocystis was significantly greater than colonies of this species from temperate waters and of the single-celled stage of its life cycle which produces no UV-B-absorbing compounds. Phaeocystis is apparently a minor dietary component of <span class="hlt">Antarctic</span> krill, Euphausia superba, and its nutritional value to crustacea is reportedly low. Phytoplankton, principally diatoms, together with fecal pellets and molted exoskeletons of grazers contribute most of the particulate carbon flux from the euphotic zone to deep water.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.G21B0871F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.G21B0871F"><span>A new research project on the interaction of the solid Earth and the <span class="hlt">Antarctic</span> Ice Sheet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fukuda, Y.; Nishijima, J.; Kazama, T.; Nakamura, K.; Doi, K.; Suganuma, Y.; Okuno, J.; Araya, A.; Kaneda, H.; Aoyama, Y.</p> <p>2017-12-01</p> <p>A new research project of "Grant-in-Aid for Scientific Research on Innovative Areas" funded by JSPS (Japan Society for the Promotion of Science) has recently been launched. The title of the project is "Giant reservoirs of heat/water/material: Global environmental changes driven by <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and <span class="hlt">Antarctic</span> Ice Sheet", and as a five years project, is aiming to establish a new research area for <span class="hlt">Antarctic</span> environmental system science. The project consists of 7 research topics, including <span class="hlt">Antarctic</span> ice sheet and <span class="hlt">Southern</span> <span class="hlt">ocean</span> sciences, new observation methodology, modeling and other interdisciplinary topics, and we are involved in the topic A02-2, "Interaction of the solid Earth and the <span class="hlt">Antarctic</span> Ice Sheet". The <span class="hlt">Antarctic</span> ice sheet, which relates to the global climate changes through the sea level rise and <span class="hlt">ocean</span> circulation, is an essential element of the Earth system for predicting the future environment changes. Thus many studies of the ice sheet changes have been conducted by means of geomorphological, geological, geodetic surveys, as well as satellite gravimetry and satellite altimetry. For these studies, one of the largest uncertainties is the effects of GIA. Therefore, GIA as a key to investigate the interaction between the solid Earth and the ice sheet changes, we plan to conduct geomorphological, geological and geodetic surveys in the inland mountain areas and the coastal areas including the surrounding areas of a Japanese station Syowa in East Antarctica, where the in-situ data for constraining GIA models are very few. Combining these new observations with other in-site data, various satellite data and numerical modeling, we aim to estimating a precise GIA model, constructing a reliable ice melting history after the last glacial maximum and obtaining the viscoelastic structure of the Earth's interior. In the presentation, we also show the five years research plans as well. This study was partially supported by JSPS KAKENHI Grant No. 17H06321.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004GBioC..18.2003C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004GBioC..18.2003C"><span>Bicarbonate uptake by <span class="hlt">Southern</span> <span class="hlt">Ocean</span> phytoplankton</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cassar, Nicolas; Laws, Edward A.; Bidigare, Robert R.; Popp, Brian N.</p> <p>2004-06-01</p> <p>Marine phytoplankton have the potential to significantly buffer future increases in atmospheric carbon dioxide levels. However, in order for CO2 fertilization to have an effect on carbon sequestration to the deep <span class="hlt">ocean</span>, the increase in dissolved CO2 must stimulate primary productivity; that is, marine phototrophs must be CO2 limited [, 1993]. Estimation of the extent of bicarbonate (HCO3-) uptake in the <span class="hlt">oceans</span> is therefore required to determine whether the anthropogenic carbon sources will enhance carbon flux to the deep <span class="hlt">ocean</span>. Using short-term 14CO2-disequilibrium experiments during the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Iron Experiment (SOFeX), we show that HCO3- uptake by <span class="hlt">Southern</span> <span class="hlt">Ocean</span> phytoplankton is significant. Since the majority of dissolved inorganic carbon (DIC) in the <span class="hlt">ocean</span> is in the form of bicarbonate, the biological pump may therefore be insensitive to anthropogenic CO2. Approximately half of the DIC uptake observed was attributable to direct HCO3- uptake, the other half being direct CO2 uptake mediated either by passive diffusion or active uptake mechanisms. The increase in growth rates and decrease in CO2 concentration associated with the iron fertilization did not trigger any noticeable changes in the mode of DIC acquisition, indicating that under most environmental conditions the carbon concentrating mechanism (CCM) is constitutive. A low-CO2 treatment induced an increase in uptake of CO2, which we attributed to increased extracellular carbonic anhydrase activity, at the expense of direct HCO3- transport across the plasmalemma. Isotopic disequilibrium experimental results are consistent with <span class="hlt">Southern</span> <span class="hlt">Ocean</span> carbon stable isotope fractionation data from this and other studies. Although iron fertilization has been shown to significantly enhance phytoplankton growth and may potentially increase carbon flux to the deep <span class="hlt">ocean</span>, an important source of the inorganic carbon taken up by phytoplankton in this study was HCO3-, whose concentration is negligibly affected by the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.A33E3237M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.A33E3237M"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> Convection and tropical telleconnections</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marinov, I.; Cabre, A.; Gnanadesikan, A.</p> <p>2014-12-01</p> <p>We show that <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (SO) temperatures in the latest generation of Earth System Models exhibit two major modes of variation, one driven by deep convection, the other by tropical variability. We perform a CMIP5 model intercomparison to understand why different climate models represent SO variability so differently in long, control simulations. We show that multiyear variability in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> sea surface temperatures (SSTs) can in turn influence <span class="hlt">oceanic</span> and atmospheric conditions in the tropics on short (atmospheric) time-scales. We argue that the strength and pattern of SO-tropical teleconnections depends on the intensity of SO deep convection. Periodic convection in the SO is a feature of most CMIP5 models under preindustrial forcing (deLavergne et al., 2014). Models show a wide distribution in the spatial extent, periodicity and intensity of their SO convection, with some models convecting most of the time, and some showing very little convection. In a highly convective coupled model, we find that multidecadal variability in SO and global SSTs, as well as SO heat storage are driven by Weddell Sea convective variability, with convective decades relatively warm due to the heat released from the deep <span class="hlt">southern</span> <span class="hlt">ocean</span> and non-convective decades cold due to the subsurface storage of heat. Furthermore, pulses of SO convection drive SST and sea ice variations, influencing absorbed shortwave and emitted longwave radiation, wind, cloud and precipitation patterns, with climatic implications for the low latitudes via fast atmospheric teleconnections. We suggest that these high-low latitude teleconnection mechanisms are relevant for understanding hiatus decades. Additionally, <span class="hlt">Southern</span> <span class="hlt">Ocean</span> deep convection varied significantly during past, natural climate changes such as during the last deglaciation. Weddell Sea open convection was recently weakened, likely as a consequence of anthropogenic forcing and the resulting surface freshening. Our study opens up the</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24451542','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24451542"><span>Impacts of the north and tropical Atlantic <span class="hlt">Ocean</span> on the <span class="hlt">Antarctic</span> Peninsula and sea ice.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Xichen; Holland, David M; Gerber, Edwin P; Yoo, Changhyun</p> <p>2014-01-23</p> <p>In recent decades, Antarctica has experienced pronounced climate changes. The <span class="hlt">Antarctic</span> Peninsula exhibited the strongest warming of any region on the planet, causing rapid changes in land ice. Additionally, in contrast to the sea-ice decline over the Arctic, <span class="hlt">Antarctic</span> sea ice has not declined, but has instead undergone a perplexing redistribution. <span class="hlt">Antarctic</span> climate is influenced by, among other factors, changes in radiative forcing and remote Pacific climate variability, but none explains the observed <span class="hlt">Antarctic</span> Peninsula warming or the sea-ice redistribution in austral winter. However, in the north and tropical Atlantic <span class="hlt">Ocean</span>, the Atlantic Multidecadal Oscillation (a leading mode of sea surface temperature variability) has been overlooked in this context. Here we show that sea surface warming related to the Atlantic Multidecadal Oscillation reduces the surface pressure in the Amundsen Sea and contributes to the observed dipole-like sea-ice redistribution between the Ross and Amundsen-Bellingshausen-Weddell seas and to the <span class="hlt">Antarctic</span> Peninsula warming. Support for these findings comes from analysis of observational and reanalysis data, and independently from both comprehensive and idealized atmospheric model simulations. We suggest that the north and tropical Atlantic is important for projections of future climate change in Antarctica, and has the potential to affect the global thermohaline circulation and sea-level change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GBioC..31..922R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GBioC..31..922R"><span>Variability in the mechanisms controlling <span class="hlt">Southern</span> <span class="hlt">Ocean</span> phytoplankton bloom phenology in an <span class="hlt">ocean</span> model and satellite observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rohr, Tyler; Long, Matthew C.; Kavanaugh, Maria T.; Lindsay, Keith; Doney, Scott C.</p> <p>2017-05-01</p> <p>A coupled global numerical simulation (conducted with the Community Earth System Model) is used in conjunction with satellite remote sensing observations to examine the role of top-down (grazing pressure) and bottom-up (light, nutrients) controls on marine phytoplankton bloom dynamics in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Phytoplankton seasonal phenology is evaluated in the context of the recently proposed "disturbance-recovery" hypothesis relative to more traditional, exclusively "bottom-up" frameworks. All blooms occur when phytoplankton division rates exceed loss rates to permit sustained net population growth; however, the nature of this decoupling period varies regionally in Community Earth System Model. Regional case studies illustrate how unique pathways allow blooms to emerge despite very poor division rates or very strong grazing rates. In the Subantarctic, southeast Pacific small spring blooms initiate early cooccurring with deep mixing and low division rates, consistent with the disturbance-recovery hypothesis. Similar systematics are present in the Subantarctic, southwest Atlantic during the spring but are eclipsed by a subsequent, larger summer bloom that is coincident with shallow mixing and the annual maximum in division rates, consistent with a bottom-up, light limited framework. In the model simulation, increased iron stress prevents a similar summer bloom in the southeast Pacific. In the simulated <span class="hlt">Antarctic</span> zone (70°S-65°S) seasonal sea ice acts as a dominant phytoplankton-zooplankton decoupling agent, triggering a delayed but substantial bloom as ice recedes. Satellite <span class="hlt">ocean</span> color remote sensing and <span class="hlt">ocean</span> physical reanalysis products do not precisely match model-predicted phenology, but observed patterns do indicate regional variability in mechanism across the Atlantic and Pacific.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20180002175&hterms=cycles&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dcycles','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20180002175&hterms=cycles&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dcycles"><span>The <span class="hlt">Ocean</span> Carbon States Database: A Proof-of-Concept Application of Cluster Analysis in the <span class="hlt">Ocean</span> Carbon Cycle</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Latto, Rebecca; Romanou, Anastasia</p> <p>2018-01-01</p> <p>In this paper, we present a database of the basic regimes of the carbon cycle in the <span class="hlt">ocean</span>, the '<span class="hlt">ocean</span> carbon states', as obtained using a data mining/pattern recognition technique in observation-based as well as model data. The goal of this study is to establish a new data analysis methodology, test it and assess its utility in providing more insights into the regional and temporal variability of the marine carbon cycle. This is important as advanced data mining techniques are becoming widely used in climate and Earth sciences and in particular in studies of the global carbon cycle, where the interaction of physical and biogeochemical drivers confounds our ability to accurately describe, understand, and predict CO2 concentrations and their changes in the major planetary carbon reservoirs. In this proof-of-concept study, we focus on using well-understood data that are based on observations, as well as model results from the NASA Goddard Institute for Space Studies (GISS) climate model. Our analysis shows that <span class="hlt">ocean</span> carbon states are associated with the subtropical-subpolar gyre during the colder months of the year and the tropics during the warmer season in the North Atlantic basin. Conversely, in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, the <span class="hlt">ocean</span> carbon states can be associated with the subtropical and <span class="hlt">Antarctic</span> convergence zones in the warmer season and the coastal <span class="hlt">Antarctic</span> divergence zone in the colder season. With respect to model evaluation, we find that the GISS model reproduces the cold and warm season regimes more skillfully in the North Atlantic than in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and matches the observed seasonality better than the spatial distribution of the regimes. Finally, the <span class="hlt">ocean</span> carbon states provide useful information in the model error attribution. Model air-sea CO2 flux biases in the North Atlantic stem from wind speed and salinity biases in the subpolar region and nutrient and wind speed biases in the subtropics and tropics. Nutrient biases are shown to be most important</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMOS43A2000T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMOS43A2000T"><span>Assessment of fine-scale parameterizations of turbulent dissipation rates in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takahashi, A.; Hibiya, T.</p> <p>2016-12-01</p> <p>To sustain the global overturning circulation, more mixing is required in the <span class="hlt">ocean</span> than has been observed. The most likely candidates for this missing mixing are breaking of wind-induced near-inertial waves and bottom-generated internal lee waves in the sparsely observed <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Nevertheless, there is a paucity of direct microstructure measurements in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> where energy dissipation rates have been estimated mostly using fine-scale parameterizations. In this study, we assess the validity of the existing fine-scale parameterizations in the <span class="hlt">Antarctic</span> Circumpolar Current (ACC) region using the data obtained from simultaneous full-depth measurements of micro-scale turbulence and fine-scale shear/strain carried out south of Australia during January 17 to February 2, 2016. Although the fine-scale shear/strain ratio (Rω) is close to the Garrett-Munk (GM) value at the station north of Subtropical Front, the values of Rω at the stations south of Subantarctic Front well exceed the GM value, suggesting that the local internal wave spectra are significantly biased to lower frequencies. We find that not all of the observed energy dissipation rates at these locations are well predicted using Gregg-Henyey-Polzin (GHP; Gregg et al., 2003) and Ijichi-Hibiya (IH; Ijichi and Hibiya, 2015) parameterizations, both of which take into account the spectral distortion in terms of Rω; energy dissipation rates at some locations are obviously overestimated by GHP and IH, although only the strain-based Wijesekera (Wijesekera et al., 1993) parameterization yields fairly good predictions. One possible explanation for this result is that a significant portion of the observed shear variance at these locations might be attributed to kinetic-energy-dominant small-scale eddies associated with the ACC, so that fine-scale strain rather than Rω becomes a more appropriate parameter to characterize the actual internal wave field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013NatGe...6..765C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013NatGe...6..765C"><span>Dynamic behaviour of the East <span class="hlt">Antarctic</span> ice sheet during Pliocene warmth</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cook, Carys P.; van de Flierdt, Tina; Williams, Trevor; Hemming, Sidney R.; Iwai, Masao; Kobayashi, Munemasa; Jimenez-Espejo, Francisco J.; Escutia, Carlota; González, Jhon Jairo; Khim, Boo-Keun; McKay, Robert M.; Passchier, Sandra; Bohaty, Steven M.; Riesselman, Christina R.; Tauxe, Lisa; Sugisaki, Saiko; Galindo, Alberto Lopez; Patterson, Molly O.; Sangiorgi, Francesca; Pierce, Elizabeth L.; Brinkhuis, Henk; Klaus, Adam; Fehr, Annick; Bendle, James A. P.; Bijl, Peter K.; Carr, Stephanie A.; Dunbar, Robert B.; Flores, José Abel; Hayden, Travis G.; Katsuki, Kota; Kong, Gee Soo; Nakai, Mutsumi; Olney, Matthew P.; Pekar, Stephen F.; Pross, Jörg; Röhl, Ursula; Sakai, Toyosaburo; Shrivastava, Prakash K.; Stickley, Catherine E.; Tuo, Shouting; Welsh, Kevin; Yamane, Masako</p> <p>2013-09-01</p> <p>Warm intervals within the Pliocene epoch (5.33-2.58 million years ago) were characterized by global temperatures comparable to those predicted for the end of this century and atmospheric CO2 concentrations similar to today. Estimates for global sea level highstands during these times imply possible retreat of the East <span class="hlt">Antarctic</span> ice sheet, but ice-proximal evidence from the <span class="hlt">Antarctic</span> margin is scarce. Here we present new data from Pliocene marine sediments recovered offshore of Adélie Land, East Antarctica, that reveal dynamic behaviour of the East <span class="hlt">Antarctic</span> ice sheet in the vicinity of the low-lying Wilkes Subglacial Basin during times of past climatic warmth. Sedimentary sequences deposited between 5.3 and 3.3 million years ago indicate increases in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> surface water productivity, associated with elevated circum-<span class="hlt">Antarctic</span> temperatures. The geochemical provenance of detrital material deposited during these warm intervals suggests active erosion of continental bedrock from within the Wilkes Subglacial Basin, an area today buried beneath the East <span class="hlt">Antarctic</span> ice sheet. We interpret this erosion to be associated with retreat of the ice sheet margin several hundreds of kilometres inland and conclude that the East <span class="hlt">Antarctic</span> ice sheet was sensitive to climatic warmth during the Pliocene.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2982231','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2982231"><span>Iron defecation by sperm whales stimulates carbon export in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Lavery, Trish J.; Roudnew, Ben; Gill, Peter; Seymour, Justin; Seuront, Laurent; Johnson, Genevieve; Mitchell, James G.; Smetacek, Victor</p> <p>2010-01-01</p> <p>The iron-limited <span class="hlt">Southern</span> <span class="hlt">Ocean</span> plays an important role in regulating atmospheric CO2 levels. Marine mammal respiration has been proposed to decrease the efficiency of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> biological pump by returning photosynthetically fixed carbon to the atmosphere. Here, we show that by consuming prey at depth and defecating iron-rich liquid faeces into the photic zone, sperm whales (Physeter macrocephalus) instead stimulate new primary production and carbon export to the deep <span class="hlt">ocean</span>. We estimate that <span class="hlt">Southern</span> <span class="hlt">Ocean</span> sperm whales defecate 50 tonnes of iron into the photic zone each year. Molar ratios of Cexport ∶Feadded determined during natural <span class="hlt">ocean</span> fertilization events are used to estimate the amount of carbon exported to the deep <span class="hlt">ocean</span> in response to the iron defecated by sperm whales. We find that <span class="hlt">Southern</span> <span class="hlt">Ocean</span> sperm whales stimulate the export of 4 × 105 tonnes of carbon per year to the deep <span class="hlt">ocean</span> and respire only 2 × 105 tonnes of carbon per year. By enhancing new primary production, the populations of 12 000 sperm whales in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> act as a carbon sink, removing 2 × 105 tonnes more carbon from the atmosphere than they add during respiration. The ability of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> to act as a carbon sink may have been diminished by large-scale removal of sperm whales during industrial whaling. PMID:20554546</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A51E2104K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A51E2104K"><span>Sensitivity of the <span class="hlt">Antarctic</span> surface mass balance to <span class="hlt">oceanic</span> perturbations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kittel, C.; Amory, C.; Agosta, C.; Fettweis, X.</p> <p>2017-12-01</p> <p>Regional climate models (RCMs) are suitable numerical tools to study the surface mass balance (SMB) of the wide polar ice sheets due to their high spatial resolution and polar-adapted physics. Nonetheless, RCMs are driven at their boundaries and over the <span class="hlt">ocean</span> by reanalysis or global climate model (GCM) products and are thus influenced by potential biases in these large-scale fields. These biases can be significant for both the atmosphere and the sea surface conditions (i.e. sea ice concentration and sea surface temperature). With the RCM MAR, a set of sensitivity experiments has been realized to assess the direct response of the SMB of the <span class="hlt">Antarctic</span> ice sheet to <span class="hlt">oceanic</span> perturbations. MAR is forced by ERA-Interim and anomalies based on mean GCM biases are introduced in sea surface conditions. Results show significant increases (decreases) of liquid and solid precipitation due to biases related to warm (cold) <span class="hlt">oceans</span>. As precipitation is mainly caused by low-pressure systems that intrude into the continent and do not penetrate far inland, coastal areas are more sensitive than inland regions. Furthermore, warm <span class="hlt">ocean</span> representative biases lead to anomalies as large as anomalies simulated by other RCMs or GCMs for the end of the 21st century.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018E%26PSL.481..136Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018E%26PSL.481..136Y"><span>Oceanographic mechanisms and penguin population increases during the Little Ice Age in the <span class="hlt">southern</span> Ross Sea, Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, Lianjiao; Sun, Liguang; Emslie, Steven D.; Xie, Zhouqing; Huang, Tao; Gao, Yuesong; Yang, Wenqing; Chu, Zhuding; Wang, Yuhong</p> <p>2018-01-01</p> <p>The Adélie penguin is a well-known indicator for climate and environmental changes. Exploring how large-scale climate variability affects penguin ecology in the past is essential for understanding the responses of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ecosystems to future global change. Using ornithogenic sediments at Cape Bird, Ross Island, Antarctica, we inferred relative population changes of Adélie penguins in the <span class="hlt">southern</span> Ross Sea over the past 500 yr, and observed an increase in penguin populations during the Little Ice Age (LIA; 1500-1850 AD). We used cadmium content in ancient penguin guano as a proxy of <span class="hlt">ocean</span> upwelling and identified a close linkage between penguin dynamics and atmospheric circulation and <span class="hlt">oceanic</span> conditions. During the cold period of ∼1600-1825 AD, a deepened Amundsen Sea Low (ASL) led to stronger winds, intensified <span class="hlt">ocean</span> upwelling, enlarged Ross Sea and McMurdo Sound polynyas, and thus higher food abundance and penguin populations. We propose a mechanism linking <span class="hlt">Antarctic</span> marine ecology and atmospheric/<span class="hlt">oceanic</span> dynamics which can help explain and predict responses of <span class="hlt">Antarctic</span> high latitudes ecosystems to climate change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.5022A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.5022A"><span>The effect of changing wind forcing on <span class="hlt">Antarctic</span> ice shelf melting in high-resolution, global sea ice-<span class="hlt">ocean</span> simulations with the Accelerated Climate Model for Energy (ACME)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Asay-Davis, Xylar; Price, Stephen; Petersen, Mark; Wolfe, Jonathan</p> <p>2017-04-01</p> <p>The capability for simulating sub-ice shelf circulation and submarine melting and freezing has recently been added to the U.S. Department of Energy's Accelerated Climate Model for Energy (ACME). With this new capability, we use an eddy permitting <span class="hlt">ocean</span> model to conduct two sets of simulations in the spirit of Spence et al. (GRL, 41, 2014), who demonstrate increased warm water upwelling along the <span class="hlt">Antarctic</span> coast in response to poleward shifting and strengthening of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> westerly winds. These characteristics, symptomatic of a positive <span class="hlt">Southern</span> Annular Mode (SAM), are projected to continue into the 21st century under anthropogenic climate change (Fyfe et al., J. Clim., 20, 2007). In our first simulation, we force the climate model using the standard CORE interannual forcing dataset (Large and Yeager; Clim. Dyn., 33, 2009). In our second simulation, we force our climate model using an altered version of CORE interannual forcing, based on the latter half of the full time series, which we take as a proxy for a future climate state biased towards a positive SAM. We compare <span class="hlt">ocean</span> model states and sub-ice shelf melt rates with observations, exploring sources of model biases as well as the effects of the two forcing scenarios.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25270127','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25270127"><span>Could the acid-base status of <span class="hlt">Antarctic</span> sea urchins indicate a better-than-expected resilience to near-future <span class="hlt">ocean</span> acidification?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Collard, Marie; De Ridder, Chantal; David, Bruno; Dehairs, Frank; Dubois, Philippe</p> <p>2015-02-01</p> <p>Increasing atmospheric carbon dioxide concentration alters the chemistry of the <span class="hlt">oceans</span> towards more acidic conditions. Polar <span class="hlt">oceans</span> are particularly affected due to their low temperature, low carbonate content and mixing patterns, for instance upwellings. Calcifying organisms are expected to be highly impacted by the decrease in the <span class="hlt">oceans</span>' pH and carbonate ions concentration. In particular, sea urchins, members of the phylum Echinodermata, are hypothesized to be at risk due to their high-magnesium calcite skeleton. However, tolerance to <span class="hlt">ocean</span> acidification in metazoans is first linked to acid-base regulation capacities of the extracellular fluids. No information on this is available to date for <span class="hlt">Antarctic</span> echinoderms and inference from temperate and tropical studies needs support. In this study, we investigated the acid-base status of 9 species of sea urchins (3 cidaroids, 2 regular euechinoids and 4 irregular echinoids). It appears that <span class="hlt">Antarctic</span> regular euechinoids seem equipped with similar acid-base regulation systems as tropical and temperate regular euechinoids but could rely on more passive ion transfer systems, minimizing energy requirements. Cidaroids have an acid-base status similar to that of tropical cidaroids. Therefore <span class="hlt">Antarctic</span> cidaroids will most probably not be affected by decreasing seawater pH, the pH drop linked to <span class="hlt">ocean</span> acidification being negligible in comparison of the naturally low pH of the coelomic fluid. Irregular echinoids might not suffer from reduced seawater pH if acidosis of the coelomic fluid pH does not occur but more data on their acid-base regulation are needed. Combining these results with the resilience of <span class="hlt">Antarctic</span> sea urchin larvae strongly suggests that these organisms might not be the expected victims of <span class="hlt">ocean</span> acidification. However, data on the impact of other global stressors such as temperature and of the combination of the different stressors needs to be acquired to assess the sensitivity of these organisms to global</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSPC14E2098P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSPC14E2098P"><span>How <span class="hlt">ocean</span> lateral mixing changes <span class="hlt">Southern</span> <span class="hlt">Ocean</span> variability in coupled climate models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pradal, M. A. S.; Gnanadesikan, A.; Thomas, J. L.</p> <p>2016-02-01</p> <p>The lateral mixing of tracers represents a major uncertainty in the formulation of coupled climate models. The mixing of tracers along density surfaces in the interior and horizontally within the mixed layer is often parameterized using a mixing coefficient ARedi. The models used in the Coupled Model Intercomparison Project 5 exhibit more than an order of magnitude range in the values of this coefficient used within the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. The impacts of such uncertainty on <span class="hlt">Southern</span> <span class="hlt">Ocean</span> variability have remained unclear, even as recent work has shown that this variability differs between different models. In this poster, we change the lateral mixing coefficient within GFDL ESM2Mc, a coarse-resolution Earth System model that nonetheless has a reasonable circulation within the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. As the coefficient varies from 400 to 2400 m2/s the amplitude of the variability varies significantly. The low-mixing case shows strong decadal variability with an annual mean RMS temperature variability exceeding 1C in the Circumpolar Current. The highest-mixing case shows a very similar spatial pattern of variability, but with amplitudes only about 60% as large. The suppression of mixing is larger in the Atlantic Sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> relatively to the Pacific sector. We examine the salinity budgets of convective regions, paying particular attention to the extent to which high mixing prevents the buildup of low-saline waters that are capable of shutting off deep convection entirely.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018BGeo...15.2393H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018BGeo...15.2393H"><span><span class="hlt">Ocean</span> acidification changes the structure of an <span class="hlt">Antarctic</span> coastal protistan community</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hancock, Alyce M.; Davidson, Andrew T.; McKinlay, John; McMinn, Andrew; Schulz, Kai G.; van den Enden, Rick L.</p> <p>2018-04-01</p> <p><span class="hlt">Antarctic</span> near-shore waters are amongst the most sensitive in the world to <span class="hlt">ocean</span> acidification. Microbes occupying these waters are critical drivers of ecosystem productivity, elemental cycling and <span class="hlt">ocean</span> biogeochemistry, yet little is known about their sensitivity to <span class="hlt">ocean</span> acidification. A six-level, dose-response experiment was conducted using 650 L incubation tanks (minicosms) adjusted to a gradient in fugacity of carbon dioxide (fCO2) from 343 to 1641 µatm. The six minicosms were filled with near-shore water from Prydz Bay, East Antarctica, and the protistan composition and abundance was determined by microscopy during 18 days of incubation. No CO2-related change in the protistan community composition was observed during the initial 8 day acclimation period under low light. Thereafter, the response of both autotrophic and heterotrophic protists to fCO2 was species-specific. The response of diatoms was mainly cell size related; microplanktonic diatoms ( > 20 µm) increased in abundance with low to moderate fCO2 (343-634 µatm) but decreased at fCO2 ≥ 953 µatm. Similarly, the abundance of Phaeocystis antarctica increased with increasing fCO2 peaking at 634 µatm. Above this threshold the abundance of micro-sized diatoms and P. antarctica fell dramatically, and nanoplanktonic diatoms ( ≤ 20 µm) dominated, therefore culminating in a significant change in the protistan community composition. Comparisons of these results with previous experiments conducted at this site show that the fCO2 thresholds are similar, despite seasonal and interannual differences in the physical and biotic environment. This suggests that near-shore microbial communities are likely to change significantly near the end of this century if anthropogenic CO2 release continues unabated, with profound ramifications for near-shore <span class="hlt">Antarctic</span> ecosystem food webs and biogeochemical cycling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMPP52A..07R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMPP52A..07R"><span>How are recent changes in <span class="hlt">Southern</span> Hemisphere Westerly Winds affecting East <span class="hlt">Antarctic</span> terrestrial plants?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Robinson, S. A.; Waterman, M. J.; Bramley-Alves, J.; Clarke, L. J.; Hua, Q.</p> <p>2017-12-01</p> <p>Antarctica has experienced major changes in temperature, wind speed, stratospheric ozone levels and ultraviolet-B radiation over the last century. However, because East Antarctica has shown little climate warming, biological changes were predicted to be relatively slow, compared to the rapid changes observed on the warmer <span class="hlt">Antarctic</span> Peninsula. Detecting the biological effects of <span class="hlt">Antarctic</span> climate change has been hindered by the paucity of long-term data sets, particularly for organisms that have been exposed to these changes throughout their lives. Recent studies using radiocarbon signals preserved along the shoots of individual mosses, as well as peat cores, enables accurate determination of the growth rates of the dominant <span class="hlt">Antarctic</span> moss flora over the last century. This allows us to explore the influence of environmental variables on growth providing a dramatic demonstration of the effects of climate change on <span class="hlt">Antarctic</span> biodiversity. We generated detailed 50-year growth records for four <span class="hlt">Antarctic</span> moss species, Ceratodon purpureus, Bryum pseudotriquetrum, Schistidium antarctici and Bryoerythrophyllum recurvirostre using the 1960s radiocarbon bomb spike. Ceratodon purpureus' growth rates are positively correlated with ozone depth and temperature and negatively correlated with wind speed. Carbon stable isotopic measurements (∂13C) suggest that the observed effects of climate variation on growth are mediated through changes in water availability and mostly likely linked to the more positive phase of the <span class="hlt">Southern</span> Annular Mode (SAM) and changing westerly wind patterns. For cold remote locations like Antarctica, where climate records are limited and of relatively short duration, this illustrates that mosses can act as microclimate proxies and have the potential to increase our knowledge of coastal <span class="hlt">Antarctic</span> climate change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29874287','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29874287"><span>Genetic structure and demographic inference of the regular sea urchin Sterechinus neumayeri (Meissner, 1900) in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>: The role of the last glaciation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Díaz, Angie; Gérard, Karin; González-Wevar, Claudio; Maturana, Claudia; Féral, Jean-Pierre; David, Bruno; Saucède, Thomas; Poulin, Elie</p> <p>2018-01-01</p> <p>One of the most relevant characteristics of the extant <span class="hlt">Southern</span> <span class="hlt">Ocean</span> fauna is its resiliency to survive glacial processes of the Quaternary. These climatic events produced catastrophic habitat reductions and forced some marine benthic species to move, adapt or go extinct. The marine benthic species inhabiting the <span class="hlt">Antarctic</span> upper continental shelf faced the Quaternary glaciations with different strategies that drastically modified population sizes and thus affected the amount and distribution of intraspecific genetic variation. Here we present new genetic information for the most conspicuous regular sea urchin of the <span class="hlt">Antarctic</span> continental shelf, Sterechinus neumayeri. We studied the patterns of genetic diversity and structure in this broadcast-spawner across three <span class="hlt">Antarctic</span> regions: <span class="hlt">Antarctic</span> Peninsula, the Weddell Sea and Adélie Land in East Antarctica. Genetic analyses based on mitochondrial and nuclear markers suggested that S. neumayeri is a single genetic unit around the <span class="hlt">Antarctic</span> continent. The species is characterized by low levels of genetic diversity and exhibits a typical star-like haplotype genealogy that supports the hypothesis of a single in situ refugium. Based on two mutation rates standardized for this genus, the Bayesian Skyline plot analyses detected a rapid demographic expansion after the Last Glacial Maximum. We propose a scenario of rapid postglacial expansion and recolonization of <span class="hlt">Antarctic</span> shallow areas from a less ice-impacted refugium where the species survived the LGM. Considering the patterns of genetic diversity and structure recorded in the species, this refugium was probably located in East Antarctica.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5991379','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5991379"><span>Genetic structure and demographic inference of the regular sea urchin Sterechinus neumayeri (Meissner, 1900) in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>: The role of the last glaciation</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Gérard, Karin; González-Wevar, Claudio; Maturana, Claudia; Féral, Jean-Pierre; David, Bruno; Saucède, Thomas; Poulin, Elie</p> <p>2018-01-01</p> <p>One of the most relevant characteristics of the extant <span class="hlt">Southern</span> <span class="hlt">Ocean</span> fauna is its resiliency to survive glacial processes of the Quaternary. These climatic events produced catastrophic habitat reductions and forced some marine benthic species to move, adapt or go extinct. The marine benthic species inhabiting the <span class="hlt">Antarctic</span> upper continental shelf faced the Quaternary glaciations with different strategies that drastically modified population sizes and thus affected the amount and distribution of intraspecific genetic variation. Here we present new genetic information for the most conspicuous regular sea urchin of the <span class="hlt">Antarctic</span> continental shelf, Sterechinus neumayeri. We studied the patterns of genetic diversity and structure in this broadcast-spawner across three <span class="hlt">Antarctic</span> regions: <span class="hlt">Antarctic</span> Peninsula, the Weddell Sea and Adélie Land in East Antarctica. Genetic analyses based on mitochondrial and nuclear markers suggested that S. neumayeri is a single genetic unit around the <span class="hlt">Antarctic</span> continent. The species is characterized by low levels of genetic diversity and exhibits a typical star-like haplotype genealogy that supports the hypothesis of a single in situ refugium. Based on two mutation rates standardized for this genus, the Bayesian Skyline plot analyses detected a rapid demographic expansion after the Last Glacial Maximum. We propose a scenario of rapid postglacial expansion and recolonization of <span class="hlt">Antarctic</span> shallow areas from a less ice-impacted refugium where the species survived the LGM. Considering the patterns of genetic diversity and structure recorded in the species, this refugium was probably located in East Antarctica. PMID:29874287</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSAH54A0112S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSAH54A0112S"><span>Temperature and pH effects on feeding and growth of <span class="hlt">Antarctic</span> krill</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saba, G.; Bockus, A.; Fantasia, R. L.; Shaw, C.; Sugla, M.; Seibel, B.</p> <p>2016-02-01</p> <p>Rapid warming in the Western <span class="hlt">Antarctic</span> Peninsula (WAP) region is occurring, and is associated with an overall decline in primary, secondary, and higher trophic levels, including <span class="hlt">Antarctic</span> krill (Euphausia superba), a key species in <span class="hlt">Antarctic</span> food webs. Additionally, there are predictions that by the end of this century the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> will be one of the first regions to be affected by seawater chemistry changes associated with enhanced CO2. <span class="hlt">Ocean</span> acidification and warming may act synergistically to impair animal performance, which may negatively impact <span class="hlt">Antarctic</span> krill. We assessed the effects of temperature (ambient temperature, ambient +3 degrees C) and pH (Experiment 1 = 8.0, 7.7; Experiment 2 = 8.0, 7.5, 7.1) on juvenile <span class="hlt">Antarctic</span> krill feeding and growth (growth increment and intermolt period) during incubation experiments at Palmer Station, Antarctica. Food intake was lower in krill exposed to reduced pH. Krill intermolt period (IMP) was significantly lower in the elevated temperature treatments (16.9 days) compared to those at 0 degrees (22.8 days). Within the elevated temperature treatment, minor increases in IMP occurred in krill exposed reduced pH. Growth increment (GI) was lower with decreased pH at the first molt, and this was exacerbated at elevated temperature. However, differences in GI were eliminated between the first and second molts suggesting potential ability of <span class="hlt">Antarctic</span> krill to acclimate to changes in temperature and pH. Reductions in juvenile krill growth and feeding under elevated temperature and reduced pH are likely caused by higher demands for internal acid-base regulation or a metabolic suppression. However, the subtlety of these feeding and growth responses leaves an open question as to how krill populations will tolerate prolonged future climate change in the <span class="hlt">Antarctic</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5510715','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5510715"><span>West <span class="hlt">Antarctic</span> Ice Sheet retreat driven by Holocene warm water incursions</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hillenbrand, Claus-Dieter; Smith, James A.; Hodell, David A.; Greaves, Mervyn; Poole, Christopher R.; Kender, Sev; Williams, Mark; Andersen, Thorbjørn Joest; Jernas, Patrycja E.; Klages, Johann P.; Roberts, Stephen J.; Gohl, Karsten; Larter, Robert D.; Kuhn, Gerhard</p> <p>2017-01-01</p> <p>Glaciological and oceanographic observations coupled with numerical models show that warm Circumpolar Deep Water (CDW) upwelling onto the West <span class="hlt">Antarctic</span> continental shelf causes melting of the undersides of floating ice shelves. Because these ice shelves buttress glaciers feeding into them, their <span class="hlt">ocean</span>-induced thinning is driving <span class="hlt">Antarctic</span> ice-sheet loss today. Here we present the first multi-proxy data based reconstruction of variability in CDW inflow to the Amundsen Sea sector, the most vulnerable part of the West <span class="hlt">Antarctic</span> Ice Sheet, during the last 11,000 years. The chemical composition of foraminifer shells and benthic foraminifer assemblages in marine sediments indicate that enhanced CDW upwelling, controlled by the latitudinal position of the <span class="hlt">Southern</span> Hemisphere westerly winds, forced deglaciation of this sector both until 7,500 years ago, when an ice-shelf collapse may have caused rapid ice-sheet thinning further upstream, and since the 1940s. These results increase confidence in the predictive capability of current ice-sheet models. PMID:28682333</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23542487','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23542487"><span>Penguins as bioindicators of mercury contamination in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>: birds from the Kerguelen Islands as a case study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Carravieri, Alice; Bustamante, Paco; Churlaud, Carine; Cherel, Yves</p> <p>2013-06-01</p> <p>Seabirds have been used extensively as bioindicators of mercury (Hg) contamination in the marine environment, although information on flightless species like penguins remains limited. In order to assess the use of penguins as bioindicators of Hg contamination in subantarctic and <span class="hlt">Antarctic</span> marine ecosystems, Hg concentrations were evaluated in the feathers of the four species that breed on the Kerguelen Islands in the <span class="hlt">southern</span> Indian <span class="hlt">Ocean</span>. Compared to other seabirds, adult Kerguelen penguins had low to moderate feather Hg concentrations, with an average ranging from 1.96 ± 0.41 μgg(-1) dry weight in the <span class="hlt">southern</span> rockhopper penguin to 5.85 ± 3.00 μg g(-1) dry weight in the gentoo penguin. The species was a major determinant of Hg contamination, with feather Hg concentrations being lower in the <span class="hlt">oceanic</span> species (king and crested penguins) than in the coastal one (gentoo penguin). In all species however, feather Hg concentrations were higher in adults than in chicks, reflecting the different periods of Hg bioaccumulation in the internal tissues of the two age classes. The relationship between adult penguin trophic ecology and Hg burdens was investigated using stable isotopes. Feeding habits (reflected by δ(15)N values) had a greater effect on adult feather Hg concentrations when compared to foraging habitats (reflected by δ(13)C values), indicating Hg biomagnification in Kerguelen neritic and <span class="hlt">oceanic</span> waters. Dietary preferences were crucial in explaining individual feather Hg concentrations, as highlighted by intra-specific variation in Hg levels of gentoo penguins sampled at two different breeding sites of the archipelago. Penguins appear to reflect Hg bioavailability reliably in their foraging environment and could serve as efficient bioindicators of Hg contamination in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> on different spatial and temporal scales. Copyright © 2013 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4032512','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4032512"><span>Meridional displacement of the <span class="hlt">Antarctic</span> Circumpolar Current</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Gille, Sarah T.</p> <p>2014-01-01</p> <p>Observed long-term warming trends in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> have been interpreted as a sign of increased poleward eddy heat transport or of a poleward displacement of the entire <span class="hlt">Antarctic</span> Circumpolar Current (ACC) frontal system. The two-decade-long record from satellite altimetry is an important source of information for evaluating the mechanisms governing these trends. While several recent studies have used sea surface height contours to index ACC frontal displacements, here altimeter data are instead used to track the latitude of mean ACC transport. Altimetric height contours indicate a poleward trend, regardless of whether they are associated with ACC fronts. The zonally averaged transport latitude index shows no long-term trend, implying that ACC meridional shifts determined from sea surface height might be associated with large-scale changes in sea surface height more than with localized shifts in frontal positions. The transport latitude index is weakly sensitive to the <span class="hlt">Southern</span> Annular Mode, but is uncorrelated with El Niño/<span class="hlt">Southern</span> Oscillation. PMID:24891396</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSPO13B..02N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSPO13B..02N"><span>A Comparison Between Internal Waves Observed in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and Lee Wave Generation Theory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nikurashin, M.; Benthuysen, J.; Naveira Garabato, A.; Polzin, K. L.</p> <p>2016-02-01</p> <p>Direct observations in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> report enhanced internal wave activity and turbulence in a few kilometers above rough bottom topography. The enhancement is co-located with the deep-reaching fronts of the <span class="hlt">Antarctic</span> Circumpolar Current, suggesting that the internal waves and turbulence are sustained by near-bottom flows interacting with rough topography. Recent numerical simulations confirm that <span class="hlt">oceanic</span> flows impinging on rough small-scale topography are very effective generators of internal gravity waves and predict vigorous wave radiation, breaking, and turbulence within a kilometer above bottom. However, a linear lee wave generation theory applied to the observed bottom topography and mean flow characteristics has been shown to overestimate the observed rates of the turbulent energy dissipation. In this study, we compare the linear lee wave theory with the internal wave kinetic energy estimated from finestructure data collected as part of the Diapycnal and Isopycnal Mixing Experiment in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (DIMES). We show that the observed internal wave kinetic energy levels are generally in agreement with the theory. Consistent with the lee wave theory, the observed internal wave kinetic energy scales quadratically with the mean flow speed, stratification, and topographic roughness. The correlation coefficient between the observed internal wave kinetic energy and mean flow and topography parameters reaches 0.6-0.8 for the 100-800 m vertical wavelengths, consistent with the dominant lee wave wavelengths, and drops to 0.2-0.5 for wavelengths outside this range. A better agreement between the lee wave theory and the observed internal wave kinetic energy than the observed turbulent energy dissipation suggests remote breaking of internal waves.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18818151','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18818151"><span>The atmospheric <span class="hlt">ocean</span>: eddies and jets in the <span class="hlt">Antarctic</span> Circumpolar Current.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Thompson, Andrew F</p> <p>2008-12-28</p> <p>Although the <span class="hlt">Antarctic</span> Circumpolar Current (ACC) is the longest and the strongest <span class="hlt">oceanic</span> current on the Earth and is the primary means of inter-basin exchange, it remains one of the most poorly represented components of global climate models. Accurately describing the circulation of the ACC is made difficult owing to the prominent role that mesoscale eddies and jets, <span class="hlt">oceanic</span> equivalents of atmospheric storms and storm tracks, have in setting the density structure and transport properties of the current. The successes and limitations of different representations of eddy processes in models of the ACC are considered, with particular attention given to how the circulation responds to changes in wind forcing. The dynamics of energetic eddies and topographically steered jets may both temper and enhance the sensitivity of different aspects of the ACC's circulation to changes in climate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27670112','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27670112"><span>Microbial mercury methylation in <span class="hlt">Antarctic</span> sea ice.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gionfriddo, Caitlin M; Tate, Michael T; Wick, Ryan R; Schultz, Mark B; Zemla, Adam; Thelen, Michael P; Schofield, Robyn; Krabbenhoft, David P; Holt, Kathryn E; Moreau, John W</p> <p>2016-08-01</p> <p>Atmospheric deposition of mercury onto sea ice and circumpolar sea water provides mercury for microbial methylation, and contributes to the bioaccumulation of the potent neurotoxin methylmercury in the marine food web. Little is known about the abiotic and biotic controls on microbial mercury methylation in polar marine systems. However, mercury methylation is known to occur alongside photochemical and microbial mercury reduction and subsequent volatilization. Here, we combine mercury speciation measurements of total and methylated mercury with metagenomic analysis of whole-community microbial DNA from <span class="hlt">Antarctic</span> snow, brine, sea ice and sea water to elucidate potential microbially mediated mercury methylation and volatilization pathways in polar marine environments. Our results identify the marine microaerophilic bacterium Nitrospina as a potential mercury methylator within sea ice. Anaerobic bacteria known to methylate mercury were notably absent from sea-ice metagenomes. We propose that <span class="hlt">Antarctic</span> sea ice can harbour a microbial source of methylmercury in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA03430.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA03430.html"><span>Extratropical Cyclone in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2001-11-07</p> <p>These images acquired on October 11, 2001 by NASA Terra satellite portray an occluded extratropical cyclone situated in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, about 650 kilometers south of the Eyre Peninsula, South Australia.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMPP52A..02K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMPP52A..02K"><span>Glacier History of the Northern <span class="hlt">Antarctic</span> Peninsula Region Since the End of the Last Ice Age and Implications for <span class="hlt">Southern</span> Hemisphere Westerly-Climate Changes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kaplan, M. R.; Schaefer, J. M.; Strelin, J. A.; Peltier, C.; Southon, J. R.; Lepper, K. E.; Winckler, G.</p> <p>2017-12-01</p> <p>For the area around James Ross Island, we present new cosmogenic 10Be exposure ages on glacial deposits, and 14C ages on associated fossil materials. These data allow us to reconstruct in detail when and how the <span class="hlt">Antarctic</span> Peninsula Ice Sheet retreated around the Island as the last Ice Age ended, and afterward when local land-based glaciers fluctuated. Similar to other studies, we found widespread deglaciation during the earliest Holocene, with fjords and bays becoming ice free between about 11,000 and 8,000 years ago. After 7,000 years ago, neoglacial type advances initiated. Then, both expansions and ice free periods occurred from the middle to late Holocene. We compare the new glacier record to those in <span class="hlt">southern</span> Patagonia, which is on the other side of the Drake Passage, and published <span class="hlt">Southern</span> <span class="hlt">Ocean</span> marine records, in order to infer past middle to high latitude changes in the <span class="hlt">Southern</span> Hemisphere Westerlies. Widespread warmth in the earliest Holocene, to the north and south of the Drake Passage, led to small glacier systems in Patagonia and wide-ranging glacier recession around the northern <span class="hlt">Antarctic</span> Peninsula. We infer that this early Holocene period of overall glacier recession - from Patagonia to the northern Peninsula - was caused by a persistent far-southerly setting of the westerlies and accompanying warm climates. Subsequently, during the middle Holocene renewed glacier expansions occurred on both sides of the Drake Passage, which reflects that the Westerlies and associated colder climate systems were generally more equatorward. From the middle to late Holocene, glacier expansions and ice free periods (and likely related ice shelf behavior) document how the Westerlies and associated higher-latitude climate systems varied.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017DSRII.139...58H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017DSRII.139...58H"><span>Macronutrient supply, uptake and recycling in the coastal <span class="hlt">ocean</span> of the west <span class="hlt">Antarctic</span> Peninsula</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Henley, Sian F.; Tuerena, Robyn E.; Annett, Amber L.; Fallick, Anthony E.; Meredith, Michael P.; Venables, Hugh J.; Clarke, Andrew; Ganeshram, Raja S.</p> <p>2017-05-01</p> <p>Nutrient supply, uptake and cycling underpin high primary productivity over the continental shelf of the west <span class="hlt">Antarctic</span> Peninsula (WAP). Here we use a suite of biogeochemical and isotopic data collected over five years in northern Marguerite Bay to examine these macronutrient dynamics and their controlling biological and physical processes in the WAP coastal <span class="hlt">ocean</span>. We show pronounced nutrient drawdown over the summer months by primary production which drives a net seasonal nitrate uptake of 1.83 mol N m-2 yr-1, equivalent to net carbon uptake of 146 g C m-2 yr-1. High primary production fuelled primarily by deep-sourced macronutrients is diatom-dominated, but non-siliceous phytoplankton also play a role. Strong nutrient drawdown in the uppermost surface <span class="hlt">ocean</span> has the potential to cause transient nitrogen limitation before nutrient resupply and/or regeneration. Interannual variability in nutrient utilisation corresponds to winter sea ice duration and the degree of upper <span class="hlt">ocean</span> mixing, implying susceptibility to physical climate change. The nitrogen isotope composition of nitrate (δ15NNO3) shows a utilisation signal during the growing seasons with a community-level net isotope effect of 4.19 ± 0.29‰. We also observe significant deviation of our data from modelled and observed utilisation trends, and argue that this is driven primarily by water column nitrification and meltwater dilution of surface nitrate. This study is important because it provides a detailed description of the nutrient biogeochemistry underlying high primary productivity at the WAP, and shows that surface <span class="hlt">ocean</span> nutrient inventories in the <span class="hlt">Antarctic</span> sea ice zone can be affected by intense recycling in the water column, meltwater dilution and sea ice processes, in addition to utilisation in the upper <span class="hlt">ocean</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMOS51E..08W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMOS51E..08W"><span>A New Species of the Genus Kiwa (Decapoda: Anomura) from the Hydrothermal Vent of the Australia-<span class="hlt">Antarctic</span> Ridge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Won, Y. J.; Lee, S. H.; Lee, W. K.</p> <p>2014-12-01</p> <p>Due to extreme weather conditions and remoteness to access, the great part of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> remains to be explored. Therefore, little is known about the Circum-<span class="hlt">Antarctic</span> Ridge (CAR) system and its hydrothermal vent ecosystem underlying the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. We report the first discovery of a new deep-sea hydrothermal vent field and a new anomuran species from the Australia-<span class="hlt">Antarctic</span> Ridge (AAR), the highest latitude (62°S; 158°E) explored in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> up to date. At this site, a new anomuran species which belongs to the genus Kiwa known as 'yeti crabs' was found. Morphologically, this species has characteristics of the genus Kiwa, including fifth pereopod inserted below sterna plastron, third sternite strongly produced anteriorly, and eyes extremely reduced. However, the new species differs from the other known species of Kiwa, K. hirsuta and K. puravida, showing relatively short rostrum and slender dactylus on second to fourth pereopods. Phylogenetic analysis using DNA sequences of eight genetic loci also supported the result of morphological analysis, confirming this species as a new Kiwa species, Kiwa n. sp. In addition, phylogenetic tree revealed the evolutionary relationship among the Kiwa species, presenting the Kiwa n. sp. as the sister species to K. puravida which inhabits the methane cold seep on the Pacific continental slope off Costa Rica. Considering the geography and the physicochemical environment, this unlikely result casts a mystery to be solved through further taxon sampling particularly from as-yet-unexplored vents and seeps. Discovery of the hydrothermal vent and Kiwa n. sp. from the AAR segment is significant because this site is located in the high latitude of the <span class="hlt">southern</span> hemisphere and it is the region affected by the <span class="hlt">Antarctic</span> Circumpolar Current (ACC). Future research on the relation of Kiwa n. sp. and the other Kiwa species affected by the ACC will provide an idea about the biogeography and the evolutionary connections of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/15013549','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/15013549"><span>Determination of the Prebomb <span class="hlt">Southern</span> (Antartic) <span class="hlt">Ocean</span> Radiocarbon in Organic Matter</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Guilderson, T P</p> <p>2001-02-26</p> <p>The <span class="hlt">Southern</span> Hemisphere is an important and unique region of the world's <span class="hlt">oceans</span> for water-mass formation and mixing, upwelling, nutrient utilization, and carbon export. In fact, one of the primary interests of the oceanographic community is to decipher the climatic record of these processes in the source or sink terms for <span class="hlt">Southern</span> <span class="hlt">Ocean</span> surface waters in the CO{sub 2} balance of the atmosphere. Current coupled <span class="hlt">ocean</span>-atmosphere modeling efforts to trace the input of CO{sub 2} into the <span class="hlt">ocean</span> imply a strong sink of anthropogenic CO{sub 2} in the <span class="hlt">southern</span> <span class="hlt">ocean</span>. However, because of its relative inaccessibility and the difficulty inmore » directly measuring CO{sub 2} fluxes in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, these results are controversial at best. An accepted diagnostic of the exchange of CO{sub 2} between the atmosphere and <span class="hlt">ocean</span> is the prebomb distribution of radiocarbon in the <span class="hlt">ocean</span> and its time-history since atmospheric nuclear testing. Such histories of {sup 14}C in the surface waters of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> do not currently exist, primarily because there are few continuous biological archives (e.g., in corals) such as those that have been used to monitor the {sup 14}C history of the tropics and subtropics. One of the possible long-term archives is the scallop Adamussium collbecki. Although not independently confirmed, relatively crude growth rate estimates of A. collbecki indicate that it has the potential to provide continuous 100 year time-series. We are exploring the suitability of this potential archive.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940026114','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940026114"><span>Dynamic constraints on CO2 uptake by an iron-fertilized <span class="hlt">Antarctic</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Peng, Tsung-Hung; Broecker, Wallace S.; Oestlund, H. G.</p> <p>1992-01-01</p> <p>The topics covered include the following: tracer distribution and dynamics in the <span class="hlt">Antarctic</span> <span class="hlt">Ocean</span>; a model of <span class="hlt">Antarctic</span> and Non-<span class="hlt">Antarctic</span> <span class="hlt">Oceans</span>; effects on an anthropogenically affected atmosphere; effects of seasonal iron fertilization; and implications of the South Atlantic Ventilation Experiment C-14 results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26163010','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26163010"><span>Effects of <span class="hlt">Southern</span> Hemisphere Wind Changes on the Meridional Overturning Circulation in <span class="hlt">Ocean</span> Models.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gent, Peter R</p> <p>2016-01-01</p> <p>Observations show that the <span class="hlt">Southern</span> Hemisphere zonal wind stress maximum has increased significantly over the past 30 years. Eddy-resolving <span class="hlt">ocean</span> models show that the resulting increase in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> mean flow meridional overturning circulation (MOC) is partially compensated by an increase in the eddy MOC. This effect can be reproduced in the non-eddy-resolving <span class="hlt">ocean</span> component of a climate model, providing the eddy parameterization coefficient is variable and not a constant. If the coefficient is a constant, then the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> mean MOC change is balanced by an unrealistically large change in the Atlantic <span class="hlt">Ocean</span> MOC. <span class="hlt">Southern</span> <span class="hlt">Ocean</span> eddy compensation means that <span class="hlt">Southern</span> Hemisphere winds cannot be the dominant mechanism driving midlatitude North Atlantic MOC variability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70027497','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70027497"><span>Deep and bottom water export from the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> to the Pacific over the past 38 million years</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>van de Flierdt, T.; Frank, M.; Halliday, A.N.; Hein, J.R.; Hattendorf, B.; Gunther, D.; Kubik, P.W.</p> <p>2004-01-01</p> <p>The application of radiogenic isotopes to the study of Cenozoic circulation patterns in the South Pacific <span class="hlt">Ocean</span> has been hampered by the fact that records from only equatorial Pacific deep water have been available. We present new Pb and Nd isotope time series for two ferromanganese crusts that grew from equatorial Pacific bottom water (D137-01, "Nova," 7219 m water depth) and southwest Pacific deep water (63KD, "Tasman," 1700 m water depth). The crusts were dated using 10Be/9Be ratios combined with constant Co-flux dating and yield time series for the past 38 and 23 Myr, respectively. The surface Nd and Pb isotope distributions are consistent with the present-day circulation pattern, and therefore the new records are considered suitable to reconstruct Eocene through Miocene paleoceanography for the South Pacific. The isotope time series of crusts Nova and Tasman suggest that equatorial Pacific deep water and waters from the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> supplied the dissolved trace metals to both sites over the past 38 Myr. Changes in the isotopic composition of crust Nova are interpreted to reflect development of the <span class="hlt">Antarctic</span> Circumpolar Current and changes in Pacific deep water circulation caused by the build up of the East <span class="hlt">Antarctic</span> Ice Sheet. The Nd isotopic composition of the shallower water site in the southwest Pacific appears to have been more sensitive to circulation changes resulting from closure of the Indonesian seaway. Copyright 2004 by the American Geophysical Union.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeoRL..42.1834F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeoRL..42.1834F"><span>Decreased calcification in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> over the satellite record</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Freeman, Natalie M.; Lovenduski, Nicole S.</p> <p>2015-03-01</p> <p>Widespread <span class="hlt">ocean</span> acidification is occurring as the <span class="hlt">ocean</span> absorbs anthropogenic carbon dioxide from the atmosphere, threatening marine ecosystems, particularly the calcifying plankton that provide the base of the marine food chain and play a key role within the global carbon cycle. We use satellite estimates of particulate inorganic carbon (PIC), surface chlorophyll, and sea surface temperature to provide a first estimate of changing calcification rates throughout the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. From 1998 to 2014 we observe a 4% basin-wide reduction in summer calcification, with ˜9% reductions in large regions (˜1 × 106 km2) of the Pacific and Indian sectors. <span class="hlt">Southern</span> <span class="hlt">Ocean</span> trends are spatially heterogeneous and primarily driven by changes in PIC concentration (suspended calcite), which has declined by ˜24% in these regions. The observed decline in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> calcification and PIC is suggestive of large-scale changes in the carbon cycle and provides insight into organism vulnerability in a changing environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUFM.A71C0116T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFM.A71C0116T"><span>Atmospheric Transport and Input of Iron to the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tindale, N. W.</p> <p>2002-12-01</p> <p>While Australia is not generally considered to be a major source of mineral dust to the atmosphere, at least compared to Asian and African desert regions, it does appear to be the main source of mineral material to the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> region south of Australia and New Zealand. In common with most of the greater <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, this region contains high nitrate, low chlorophyll (HNLC) waters. Recent open <span class="hlt">ocean</span> iron enrichment experiments in this region have demonstrated that phytoplankton growth and biomass are limited by iron availability. However the flux of atmospheric iron to this open <span class="hlt">ocean</span> region is poorly known with very few direct measurements of mineral aerosol levels and input. Using mineral aerosol samples collected on Macquarie Island and at Cape Grim, together with other chemical data, air mass trajectories and satellite data, the spatial and temporal variability of aerosol iron transport and input to the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> region south of Australia is estimated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850017722&hterms=worlds+oceans&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dworlds%2Boceans','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850017722&hterms=worlds+oceans&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dworlds%2Boceans"><span>North Atlantic Deep Water and the World <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gordon, A. L.</p> <p>1984-01-01</p> <p>North Atlantic Deep Water (NADW) by being warmer and more saline than the average abyssal water parcel introduces heat and salt into the abyssal <span class="hlt">ocean</span>. The source of these properties is upper layer or thermocline water considered to occupy the <span class="hlt">ocean</span> less dense than sigma-theta of 27.6. That NADW convects even though it's warmer than the abyssal <span class="hlt">ocean</span> is obviously due to the high salinity. In this way, NADW formation may be viewed as saline convection. The counter force removing heat and salinity (or introducing fresh water) is usually considered to to take place in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> where upwelling deep water is converted to cold fresher <span class="hlt">Antarctic</span> water masses. The <span class="hlt">Southern</span> <span class="hlt">ocean</span> convective process is driven by low temperatures and hence may be considered as thermal convection. A significant fresh water source may also occur in the North Pacific where the northward flowing of abyssal water from the <span class="hlt">Southern</span> circumpolar belt is saltier and denser than the southward flowing, return abyssal water. The source of the low salinity input may be vertical mixing of the low salinity surface water or the low salinity intermediate water.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2901456','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2901456"><span>Abrupt change of <span class="hlt">Antarctic</span> moisture origin at the end of Termination II</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Masson-Delmotte, V.; Stenni, B.; Blunier, T.; Cattani, O.; Chappellaz, J.; Cheng, H.; Dreyfus, G.; Edwards, R. L.; Falourd, S.; Govin, A.; Kawamura, K.; Johnsen, S. J.; Jouzel, J.; Landais, A.; Lemieux-Dudon, B.; Lourantou, A.; Marshall, G.; Minster, B.; Mudelsee, M.; Pol, K.; Röthlisberger, R.; Selmo, E.; Waelbroeck, C.</p> <p>2010-01-01</p> <p>The deuterium excess of polar ice cores documents past changes in evaporation conditions and moisture origin. New data obtained from the European Project for Ice Coring in Antarctica Dome C East <span class="hlt">Antarctic</span> ice core provide new insights on the sequence of events involved in Termination II, the transition between the penultimate glacial and interglacial periods. This termination is marked by a north–south seesaw behavior, with first a slow methane concentration rise associated with a strong <span class="hlt">Antarctic</span> temperature warming and a slow deuterium excess rise. This first step is followed by an abrupt north Atlantic warming, an abrupt resumption of the East Asian summer monsoon, a sharp methane rise, and a CO2 overshoot, which coincide within dating uncertainties with the end of <span class="hlt">Antarctic</span> optimum. Here, we show that this second phase is marked by a very sharp Dome C centennial deuterium excess rise, revealing abrupt reorganization of atmospheric circulation in the <span class="hlt">southern</span> Indian <span class="hlt">Ocean</span> sector. PMID:20566887</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4461077','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4461077"><span>Responses of <span class="hlt">ocean</span> circulation and carbon cycle to changes in the position of the <span class="hlt">Southern</span> Hemisphere westerlies at Last Glacial Maximum</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Völker, Christoph; Köhler, Peter</p> <p>2013-01-01</p> <p>We explore the impact of a latitudinal shift in the westerly wind belt over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> on the Atlantic meridional overturning circulation (AMOC) and on the carbon cycle for Last Glacial Maximum background conditions using a state-of-the-art <span class="hlt">ocean</span> general circulation model. We find that a southward (northward) shift in the westerly winds leads to an intensification (weakening) of no more than 10% of the AMOC. This response of the <span class="hlt">ocean</span> physics to shifting winds agrees with other studies starting from preindustrial background climate, but the responsible processes are different. In our setup changes in AMOC seemed to be more pulled by upwelling in the south than pushed by downwelling in the north, opposite to what previous studies with different background climate are suggesting. The net effects of the changes in <span class="hlt">ocean</span> circulation lead to a rise in atmospheric pCO2 of less than 10 μatm for both northward and southward shift in the winds. For northward shifted winds the zone of upwelling of carbon- and nutrient-rich waters in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is expanded, leading to more CO2outgassing to the atmosphere but also to an enhanced biological pump in the subpolar region. For southward shifted winds the upwelling region contracts around Antarctica, leading to less nutrient export northward and thus a weakening of the biological pump. These model results do not support the idea that shifts in the westerly wind belt play a dominant role in coupling atmospheric CO2 rise and <span class="hlt">Antarctic</span> temperature during deglaciation suggested by the ice core data. PMID:26074663</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26074663','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26074663"><span>Responses of <span class="hlt">ocean</span> circulation and carbon cycle to changes in the position of the <span class="hlt">Southern</span> Hemisphere westerlies at Last Glacial Maximum.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Völker, Christoph; Köhler, Peter</p> <p>2013-12-01</p> <p>We explore the impact of a latitudinal shift in the westerly wind belt over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> on the Atlantic meridional overturning circulation (AMOC) and on the carbon cycle for Last Glacial Maximum background conditions using a state-of-the-art <span class="hlt">ocean</span> general circulation model. We find that a southward (northward) shift in the westerly winds leads to an intensification (weakening) of no more than 10% of the AMOC. This response of the <span class="hlt">ocean</span> physics to shifting winds agrees with other studies starting from preindustrial background climate, but the responsible processes are different. In our setup changes in AMOC seemed to be more pulled by upwelling in the south than pushed by downwelling in the north, opposite to what previous studies with different background climate are suggesting. The net effects of the changes in <span class="hlt">ocean</span> circulation lead to a rise in atmospheric p CO 2 of less than 10 μatm for both northward and southward shift in the winds. For northward shifted winds the zone of upwelling of carbon- and nutrient-rich waters in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is expanded, leading to more CO 2 outgassing to the atmosphere but also to an enhanced biological pump in the subpolar region. For southward shifted winds the upwelling region contracts around Antarctica, leading to less nutrient export northward and thus a weakening of the biological pump. These model results do not support the idea that shifts in the westerly wind belt play a dominant role in coupling atmospheric CO 2 rise and <span class="hlt">Antarctic</span> temperature during deglaciation suggested by the ice core data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17405207','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17405207"><span>The biodiversity of the deep <span class="hlt">Southern</span> <span class="hlt">Ocean</span> benthos.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Brandt, A; De Broyer, C; De Mesel, I; Ellingsen, K E; Gooday, A J; Hilbig, B; Linse, K; Thomson, M R A; Tyler, P A</p> <p>2007-01-29</p> <p>Our knowledge of the biodiversity of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (SO) deep benthos is scarce. In this review, we describe the general biodiversity patterns of meio-, macro- and megafaunal taxa, based on historical and recent expeditions, and against the background of the geological events and phylogenetic relationships that have influenced the biodiversity and evolution of the investigated taxa. The relationship of the fauna to environmental parameters, such as water depth, sediment type, food availability and carbonate solubility, as well as species interrelationships, probably have shaped present-day biodiversity patterns as much as evolution. However, different taxa exhibit different large-scale biodiversity and biogeographic patterns. Moreover, there is rarely any clear relationship of biodiversity pattern with depth, latitude or environmental parameters, such as sediment composition or grain size. Similarities and differences between the SO biodiversity and biodiversity of global <span class="hlt">oceans</span> are outlined. The high percentage (often more than 90%) of new species in almost all taxa, as well as the high degree of endemism of many groups, may reflect undersampling of the area, and it is likely to decrease as more information is gathered about SO deep-sea biodiversity by future expeditions. Indeed, among certain taxa such as the Foraminifera, close links at the species level are already apparent between deep Weddell Sea faunas and those from similar depths in the North Atlantic and Arctic. With regard to the vertical zonation from the shelf edge into deep water, biodiversity patterns among some taxa in the SO might differ from those in other deep-sea areas, due to the deep <span class="hlt">Antarctic</span> shelf and the evolution of eurybathy in many species, as well as to deep-water production that can fuel the SO deep sea with freshly produced organic matter derived not only from phytoplankton, but also from ice algae.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1764829','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1764829"><span>The biodiversity of the deep <span class="hlt">Southern</span> <span class="hlt">Ocean</span> benthos</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Brandt, A; De Broyer, C; De Mesel, I; Ellingsen, K.E; Gooday, A.J; Hilbig, B; Linse, K; Thomson, M.R.A; Tyler, P.A</p> <p>2006-01-01</p> <p>Our knowledge of the biodiversity of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (SO) deep benthos is scarce. In this review, we describe the general biodiversity patterns of meio-, macro- and megafaunal taxa, based on historical and recent expeditions, and against the background of the geological events and phylogenetic relationships that have influenced the biodiversity and evolution of the investigated taxa. The relationship of the fauna to environmental parameters, such as water depth, sediment type, food availability and carbonate solubility, as well as species interrelationships, probably have shaped present-day biodiversity patterns as much as evolution. However, different taxa exhibit different large-scale biodiversity and biogeographic patterns. Moreover, there is rarely any clear relationship of biodiversity pattern with depth, latitude or environmental parameters, such as sediment composition or grain size. Similarities and differences between the SO biodiversity and biodiversity of global <span class="hlt">oceans</span> are outlined. The high percentage (often more than 90%) of new species in almost all taxa, as well as the high degree of endemism of many groups, may reflect undersampling of the area, and it is likely to decrease as more information is gathered about SO deep-sea biodiversity by future expeditions. Indeed, among certain taxa such as the Foraminifera, close links at the species level are already apparent between deep Weddell Sea faunas and those from similar depths in the North Atlantic and Arctic. With regard to the vertical zonation from the shelf edge into deep water, biodiversity patterns among some taxa in the SO might differ from those in other deep-sea areas, due to the deep <span class="hlt">Antarctic</span> shelf and the evolution of eurybathy in many species, as well as to deep-water production that can fuel the SO deep sea with freshly produced organic matter derived not only from phytoplankton, but also from ice algae. PMID:17405207</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22325720','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22325720"><span>Immunoglobulin from <span class="hlt">Antarctic</span> fish species of Rajidae family.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Coscia, Maria Rosaria; Cocca, Ennio; Giacomelli, Stefano; Cuccaro, Fausta; Oreste, Umberto</p> <p>2012-03-01</p> <p>Immunoglobulins (Ig) of Chondroichthyes have been extensively studied in sharks; in contrast, in skates investigations on Ig remain scarce and fragmentary despite the high occurrence of skates in all of the major <span class="hlt">oceans</span> of the world. To focus on Rajidae Igμ, the most abundant heavy chain isotype, we have chosen the <span class="hlt">Antarctic</span> species Bathyraja eatonii, Bathyraja albomaculata, Bathyraja brachyurops, and Amblyraja georgiana which live at high latitudes in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, and at very low temperatures. We prepared mRNA from the spleen of individuals of each species and performed RT-PCR experiments using two oligonucleotides designed on the alignment of various elasmobranch Igμ heavy chain sequences available in GenBank. The PCR products, about 1400-nt long, were cloned and sequenced. Nucleotide sequence identities calculated for the constant region domains ranged from 88.5% to 97.5% between species, and from 91.1% to 99.7% within species. In a distance tree, including also Raja erinacea sequences, two major branches were obtained, one containing Arhynchobatinae sequences, the other one Rajinae sequences. Four presumptive D gene segments were identified in the region of the VH/D/JH recombination; two different D segments were often found in the same sequence. Moreover, 5-15 genomic fragments of different lengths, carrying the gene locus encoding Igμ chain were revealed by <span class="hlt">Southern</span> blotting analysis. B. eatonii amino acid sequences were analyzed for the positional diversity by Shannon entropy analysis, showing CH4 as the most conserved domain, and CH3 as the most variable one. B. eatonii CDR3 region length varied between 11 and 15 amino acid residues; the mean length (13.4 aa) was greater than that of Leucoraja eglanteria sequences (7.7 aa). An alignment of representative sequences of <span class="hlt">Antarctic</span> species and R. erinacea showed that more cysteine residues not involved in the intradomain disulfide bridges were present in <span class="hlt">Antarctic</span> species. Copyright © 2011 Elsevier</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4371949','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4371949"><span><span class="hlt">Ocean</span>-driven thinning enhances iceberg calving and retreat of <span class="hlt">Antarctic</span> ice shelves</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Liu, Yan; Moore, John C.; Cheng, Xiao; Gladstone, Rupert M.; Bassis, Jeremy N.; Liu, Hongxing; Wen, Jiahong; Hui, Fengming</p> <p>2015-01-01</p> <p>Iceberg calving from all <span class="hlt">Antarctic</span> ice shelves has never been directly measured, despite playing a crucial role in ice sheet mass balance. Rapid changes to iceberg calving naturally arise from the sporadic detachment of large tabular bergs but can also be triggered by climate forcing. Here we provide a direct empirical estimate of mass loss due to iceberg calving and melting from <span class="hlt">Antarctic</span> ice shelves. We find that between 2005 and 2011, the total mass loss due to iceberg calving of 755 ± 24 gigatonnes per year (Gt/y) is only half the total loss due to basal melt of 1516 ± 106 Gt/y. However, we observe widespread retreat of ice shelves that are currently thinning. Net mass loss due to iceberg calving for these ice shelves (302 ± 27 Gt/y) is comparable in magnitude to net mass loss due to basal melt (312 ± 14 Gt/y). Moreover, we find that iceberg calving from these decaying ice shelves is dominated by frequent calving events, which are distinct from the less frequent detachment of isolated tabular icebergs associated with ice shelves in neutral or positive mass balance regimes. Our results suggest that thinning associated with <span class="hlt">ocean</span>-driven increased basal melt can trigger increased iceberg calving, implying that iceberg calving may play an overlooked role in the demise of shrinking ice shelves, and is more sensitive to <span class="hlt">ocean</span> forcing than expected from steady state calving estimates. PMID:25733856</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28645049','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28645049"><span>Gaseous elemental mercury in the marine boundary layer and air-sea flux in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in austral summer.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Jiancheng; Xie, Zhouqing; Wang, Feiyue; Kang, Hui</p> <p>2017-12-15</p> <p>Gaseous elemental mercury (GEM) in the marine boundary layer (MBL), and dissolved gaseous mercury (DGM) in surface seawater of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> were measured in the austral summer from December 13, 2014 to February 1, 2015. GEM concentrations in the MBL ranged from 0.4 to 1.9ngm -3 (mean±standard deviation: 0.9±0.2ngm -3 ), whereas DGM concentrations in surface seawater ranged from 7.0 to 75.9pgL -1 (mean±standard deviation: 23.7±13.2pgL -1 ). The occasionally observed low GEM in the MBL suggested either the occurrence of atmospheric mercury depletion in summer, or the transport of GEM-depleted air from the <span class="hlt">Antarctic</span> Plateau. Elevated GEM concentrations in the MBL and DGM concentrations in surface seawater were consistently observed in the ice-covered region of the Ross Sea implying the influence of the sea ice environment. Diminishing sea ice could cause more mercury evasion from the <span class="hlt">ocean</span> to the air. Using the thin film gas exchange model, the air-sea fluxes of gaseous mercury in non-ice-covered area during the study period were estimated to range from 0.0 to 6.5ngm -2 h -1 with a mean value of 1.5±1.8ngm -2 h -1 , revealing GEM (re-)emission from the East <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in summer. Copyright © 2017 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993JGR....98.2419C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993JGR....98.2419C"><span>Coastal zone color scanner pigment concentrations in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and relationships to geophysical surface features</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Comiso, J. C.; McClain, C. R.; Sullivan, C. W.; Ryan, J. P.; Leonard, C. L.</p> <p>1993-02-01</p> <p>The spatial and seasonal distributions of phytoplankton pigment concentration over the entire <span class="hlt">southern</span> <span class="hlt">ocean</span> have been studied for the first time using the coastal zone color scanner historical data set (from October 1978 through June 1986). Enhanced pigment concentrations are observed between 35°S and 55°S throughout the year, with such enhanced regions being more confined to the south in the austral summer and extending further north in the winter. North and south of the polar front, phytoplankton blooms (>1 mg/m3) are not uniformly distributed around the circumpolar region. Instead, blooms appear to be located in regions of ice retreat (or high melt areas) such as the Scotia Sea and the Ross Sea, in relatively shallow areas (e.g., the Patagonian and the New Zealand shelves), in some regions of Ekman upwelling like the Tasman Sea, and near areas of high eddy kinetic energy such as the Agulhas retroflection. Among all features examined by regression analysis, bathymetry appears to be the one most consistently correlated with pigments (correlation coefficient being about -0.3 for the entire region). The cause of negative correlation with bathymetry is unknown but is consistent with the observed abundance of iron in shallow areas in the <span class="hlt">Antarctic</span> region. It is also consistent with resuspension of phytoplankton cells by wind-induced mixing, especially in shallow waters. On the other hand, in the deep <span class="hlt">ocean</span> (especially at latitudes <45°S where surface nutrients may be limiting), upwelling induced by topographic features may cause resupply of nutrients to the surface and shoaling of the subsurface chlorophyll maximum. Low pigment values are common at low latitudes and in regions of high wind stress, where deep mixing and net loss of surface pigment occur. Nutrients (phosphate, nitrate, and silicate) are found to correlate significantly with pigments when the entire <span class="hlt">southern</span> <span class="hlt">ocean</span> is considered, but south of 55°S the correlation is poor, probably because the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018TCry...12.1969R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018TCry...12.1969R"><span><span class="hlt">Antarctic</span> sub-shelf melt rates via PICO</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reese, Ronja; Albrecht, Torsten; Mengel, Matthias; Asay-Davis, Xylar; Winkelmann, Ricarda</p> <p>2018-06-01</p> <p><span class="hlt">Ocean</span>-induced melting below ice shelves is one of the dominant drivers for mass loss from the <span class="hlt">Antarctic</span> Ice Sheet at present. An appropriate representation of sub-shelf melt rates is therefore essential for model simulations of marine-based ice sheet evolution. Continental-scale ice sheet models often rely on simple melt-parameterizations, in particular for long-term simulations, when fully coupled ice-<span class="hlt">ocean</span> interaction becomes computationally too expensive. Such parameterizations can account for the influence of the local depth of the ice-shelf draft or its slope on melting. However, they do not capture the effect of <span class="hlt">ocean</span> circulation underneath the ice shelf. Here we present the Potsdam Ice-shelf Cavity mOdel (PICO), which simulates the vertical overturning circulation in ice-shelf cavities and thus enables the computation of sub-shelf melt rates consistent with this circulation. PICO is based on an <span class="hlt">ocean</span> box model that coarsely resolves ice shelf cavities and uses a boundary layer melt formulation. We implement it as a module of the Parallel Ice Sheet Model (PISM) and evaluate its performance under present-day conditions of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. We identify a set of parameters that yield two-dimensional melt rate fields that qualitatively reproduce the typical pattern of comparably high melting near the grounding line and lower melting or refreezing towards the calving front. PICO captures the wide range of melt rates observed for <span class="hlt">Antarctic</span> ice shelves, with an average of about 0.1 m a-1 for cold sub-shelf cavities, for example, underneath Ross or Ronne ice shelves, to 16 m a-1 for warm cavities such as in the Amundsen Sea region. This makes PICO a computationally feasible and more physical alternative to melt parameterizations purely based on ice draft geometry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.C13G..02S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.C13G..02S"><span><span class="hlt">Antarctic</span> grounding-line migration</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Slater, T.; Konrad, H.; Shepherd, A.; Gilbert, L.; Hogg, A.; McMillan, M.; Muir, A. S.</p> <p>2017-12-01</p> <p>Knowledge of grounding-line position is critical for quantifying ice discharge into the <span class="hlt">ocean</span>, as a boundary condition for numerical models of ice flow, and as an indicator of ice sheet stability. Although geological investigations have documented extensive grounding-line retreat since the period of the Last Glacial Maximum, observations of grounding line migration during the satellite era are restricted to a handful of locations. We combine satellite altimeter observations of ice-elevation change and airborne measurements of ice geometry to track movement of the <span class="hlt">Antarctic</span> Ice Sheet grounding line. Based on these data, we estimate that 22%, 3%, and 10% of the West <span class="hlt">Antarctic</span>, East <span class="hlt">Antarctic</span>, and <span class="hlt">Antarctic</span> Peninsula ice sheet grounding lines are retreating at rates faster than the typical pace since the Last Glacial Maximum, and that the continent loses over 200 km2 of grounded-ice area per year. Although by far the fastest rates of retreat occurred in the Amundsen Sea Sector, the Pine Island Glacier grounding line has stabilized - likely as a consequence of abated <span class="hlt">ocean</span> forcing during the survey period.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1811977P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1811977P"><span>Sea-level response to abrupt <span class="hlt">ocean</span> warming of <span class="hlt">Antarctic</span> ice shelves</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pattyn, Frank</p> <p>2016-04-01</p> <p>Antarctica's contribution to global sea-level rise increases steadily. A fundamental question remains whether the ice discharge will lead to marine ice sheet instability (MISI) and collapse of certain sectors of the ice sheet or whether ice loss will increase linearly with the warming trends. Therefore, we employ a newly developed ice sheet model of the <span class="hlt">Antarctic</span> ice sheet, called f.ETISh (fast Elementary Thermomechanical Ice Sheet model) to simulate ice sheet response to abrupt perturbations in <span class="hlt">ocean</span> and atmospheric temperature. The f.ETISh model is a vertically integrated hybrid (SSA/SIA) ice sheet model including ice shelves. Although vertically integrated, thermomechanical coupling is ensured through a simplified representation of ice sheet thermodynamics based on an analytical solution of the vertical temperature profile, including strain heating and horizontal advection. The marine boundary is represented by a flux condition either coherent with power-law basal sliding (Pollard & Deconto (2012) based on Schoof (2007)) or according to Coulomb basal friction (Tsai et al., 2015), both taking into account ice-shelf buttressing. Model initialization is based on optimization of the basal friction field. Besides the traditional MISMIP tests, new tests with respect to MISI in plan-view models have been devised. The model is forced with stepwise <span class="hlt">ocean</span> and atmosphere temperature perturbations. The former is based on a parametrised sub-shelf melt (limited to ice shelves), while the latter is based on present-day mass balance/surface temperature and corrected for elevation changes. Surface melting is introduced using a PDD model. Results show a general linear response in mass loss to <span class="hlt">ocean</span> warming. Nonlinear response due to MISI occurs under specific conditions and is highly sensitive to the basal conditions near the grounding line, governed by both the initial conditions and the basal sliding/deformation model. The Coulomb friction model leads to significantly higher</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014NatSR...4E4046R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014NatSR...4E4046R"><span>A <span class="hlt">Southern</span> <span class="hlt">Ocean</span> trigger for Northwest Pacific ventilation during the Holocene?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rella, S. F.; Uchida, M.</p> <p>2014-02-01</p> <p>Holocene <span class="hlt">ocean</span> circulation is poorly understood due to sparsity of dateable marine archives with submillennial-scale resolution. Here we present a record of mid-depth water radiocarbon contents in the Northwest (NW) Pacific <span class="hlt">Ocean</span> over the last 12.000 years, which shows remarkable millennial-scale variations relative to changes in atmospheric radiocarbon inventory. Apparent decoupling of these variations from regional ventilation and mixing processes leads us to the suggestion that the mid-depth NW Pacific may have responded to changes in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> overturning forced by latitudinal displacements of the <span class="hlt">southern</span> westerly winds. By inference, a tendency of in-phase related North Atlantic and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> overturning would argue against the development of a steady bipolar seesaw regime during the Holocene.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24509792','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24509792"><span>A <span class="hlt">Southern</span> <span class="hlt">Ocean</span> trigger for Northwest Pacific ventilation during the Holocene?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rella, S F; Uchida, M</p> <p>2014-02-17</p> <p>Holocene <span class="hlt">ocean</span> circulation is poorly understood due to sparsity of dateable marine archives with submillennial-scale resolution. Here we present a record of mid-depth water radiocarbon contents in the Northwest (NW) Pacific <span class="hlt">Ocean</span> over the last 12.000 years, which shows remarkable millennial-scale variations relative to changes in atmospheric radiocarbon inventory. Apparent decoupling of these variations from regional ventilation and mixing processes leads us to the suggestion that the mid-depth NW Pacific may have responded to changes in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> overturning forced by latitudinal displacements of the <span class="hlt">southern</span> westerly winds. By inference, a tendency of in-phase related North Atlantic and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> overturning would argue against the development of a steady bipolar seesaw regime during the Holocene.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4027855','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4027855"><span>A <span class="hlt">Southern</span> <span class="hlt">Ocean</span> trigger for Northwest Pacific ventilation during the Holocene?</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Rella, S. F.; Uchida, M.</p> <p>2014-01-01</p> <p>Holocene <span class="hlt">ocean</span> circulation is poorly understood due to sparsity of dateable marine archives with submillennial-scale resolution. Here we present a record of mid-depth water radiocarbon contents in the Northwest (NW) Pacific <span class="hlt">Ocean</span> over the last 12.000 years, which shows remarkable millennial-scale variations relative to changes in atmospheric radiocarbon inventory. Apparent decoupling of these variations from regional ventilation and mixing processes leads us to the suggestion that the mid-depth NW Pacific may have responded to changes in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> overturning forced by latitudinal displacements of the <span class="hlt">southern</span> westerly winds. By inference, a tendency of in-phase related North Atlantic and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> overturning would argue against the development of a steady bipolar seesaw regime during the Holocene. PMID:24509792</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS43H..01N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS43H..01N"><span>From mesoscale eddies to small-scale turbulence in the <span class="hlt">Antarctic</span> Circumpolar Current</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Naveira Garabato, A.; Brearley, J. A.; Sheen, K. L.; Waterman, S. N.</p> <p>2012-12-01</p> <p>A foremost question in physical oceanography is that of how the <span class="hlt">oceanic</span> mesoscale dissipates. The <span class="hlt">Antarctic</span> Circumpolar Current (ACC), in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, is forced strongly by the wind and hosts a vigorous mesoscale eddy field. It has been recently suggested that substantial dampening of mesoscale flows in the region may occur through interactions with topography, on the basis of a number of indirect approaches. Here, we present the first direct evidence of a transfer of energy between mesoscale eddies and small-scale turbulence in the ACC, via the radiation, instability and breaking of internal waves generated as mesoscale flows impinge on rough topography. The evidence is provided by analysis of two data sets gathered by the DIMES (Diapycnal and Isopycnal Experiment in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>) experiment: (1) the observations of a mooring cluster, specifically designed to measure dynamical exchanges between the mesoscale eddy and internal wave fields in Drake Passage over a 2-year deployment; and (2) an extensive fine- and microstructure survey of the region. The physical mechanisms implicated in the cascade of energy across scales will be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.8811S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.8811S"><span>Shallow Carbon Export from an Iron fertilised Plankton Bloom in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sanders, R.; Pollard, R.; Morris, P.; Statham, P.; Moore, C. M. M.; Lucas, M.</p> <p>2009-04-01</p> <p>Some regions of the global <span class="hlt">ocean</span>, notably the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, have high levels of macronutrients yet low levels of chlorophyll (the high nutrient, low chlorophyll or HNLC condition). Numerous artificial iron fertilization experiments conducted in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> have resulted in enhanced phytoplankton biomass and macronutrient drawdown. However the subsequent long-term biogeochemical consequences of such iron fertilization are unclear due in part to the limited size and duration of such experiments. An alternative way to assess the affect of iron over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> biological carbon pump is to observe the evolution of plankton production in regions of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> where shallow topography and <span class="hlt">Ocean</span> currents interact to promote to release terrestrial iron into HNLC waters. During 2004-5 RRS Discovery conduced a complex programme of observations in such a region around the Crozet Islands in the SW Indian <span class="hlt">Ocean</span>. The results of this programme, focussing on a quantitative estimate of carbon export per unit iron addition, will be presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20150021521&hterms=sea&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dsea','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20150021521&hterms=sea&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dsea"><span>An Assessment of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Water Masses and Sea Ice During 1988-2007 in a Suite of Interannual CORE-II Simulations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Downes, Stephanie M.; Farneti, Riccardo; Uotila, Petteri; Griffies, Stephen M.; Marsland, Simon J.; Bailey, David; Behrens, Erik; Bentsen, Mats; Bi, Daohua; Biastoch, Arne; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20150021521'); toggleEditAbsImage('author_20150021521_show'); toggleEditAbsImage('author_20150021521_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20150021521_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20150021521_hide"></p> <p>2015-01-01</p> <p>We characterise the representation of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> water mass structure and sea ice within a suite of 15 global <span class="hlt">ocean</span>-ice models run with the Coordinated <span class="hlt">Ocean</span>-ice Reference Experiment Phase II (CORE-II) protocol. The main focus is the representation of the present (1988-2007) mode and intermediate waters, thus framing an analysis of winter and summer mixed layer depths; temperature, salinity, and potential vorticity structure; and temporal variability of sea ice distributions. We also consider the interannual variability over the same 20 year period. Comparisons are made between models as well as to observation-based analyses where available. The CORE-II models exhibit several biases relative to <span class="hlt">Southern</span> <span class="hlt">Ocean</span> observations, including an underestimation of the model mean mixed layer depths of mode and intermediate water masses in March (associated with greater <span class="hlt">ocean</span> surface heat gain), and an overestimation in September (associated with greater high latitude <span class="hlt">ocean</span> heat loss and a more northward winter sea-ice extent). In addition, the models have cold and fresh/warm and salty water column biases centred near 50 deg S. Over the 1988-2007 period, the CORE-II models consistently simulate spatially variable trends in sea-ice concentration, surface freshwater fluxes, mixed layer depths, and 200-700 m <span class="hlt">ocean</span> heat content. In particular, sea-ice coverage around most of the <span class="hlt">Antarctic</span> continental shelf is reduced, leading to a cooling and freshening of the near surface waters. The shoaling of the mixed layer is associated with increased surface buoyancy gain, except in the Pacific where sea ice is also influential. The models are in disagreement, despite the common CORE-II atmospheric state, in their spatial pattern of the 20-year trends in the mixed layer depth and sea-ice.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015FrES....9..742M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015FrES....9..742M"><span>Adaptations of phytoplankton in the Indian <span class="hlt">Ocean</span> sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> during austral summer of 1998—2014</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mishra, R. K.; Naik, R. K.; Anil Kumar, N.</p> <p>2015-12-01</p> <p>This study investigates the effects of light and temperature on the surface water diatoms and chlorophytes, phytoplankton in the Indian <span class="hlt">Ocean</span> sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (SO) during the austral summer of 1998‒2014. Significant longitudinal variations in hydrographic and biological parameters were observed at the Sub tropical front (STF), Sub <span class="hlt">Antarctic</span> front (SAF) and Polar front (PF) along 56°E‒58°E. The concentrations of total surface chlorophyll a ( Chl a), diatoms, and chlorophytes measured by the National Aeronautics Space Agency (NASA) estimated by the Sea-Viewing Wide Field-of-View Sensors (SeaWiFS), the Moderate Resolution Imaging Spectro Radiometer (MODIS), and the NASA <span class="hlt">Ocean</span> Biological Model (NOBM) were used in the study. Variations in the concentration of total Chl a was remarkable amongst the fronts during the study period. The contribution of diatoms to the total concentration of surface Chl a increased towards south from the STF to the PF while it decreased in the case of chlorophytes. The maximum photosynthetically active radiation (PAR) was observed at the STF and it progressively decreased to the PF through the SAF. At the PF region the contribution of diatoms to the total Chl a biomass was ≥80%. On the other hand, the chlorophytes showed a contrary distribution pattern with ≥70% of the total Chl a biomass recorded at the STF which gradually decreased towards the PF, mainly attributed to the temperate adaptation. This clearly reveals that the trend of diatoms increased at the STF and decreased at the SAF and the PF. Further, the trend of chlorophytes was increased at the STF, SAF and PF with a shift in the community in the frontal system of the Indian <span class="hlt">Ocean</span> sector of the SO.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29670936','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29670936"><span>Submesoscale Rossby waves on the <span class="hlt">Antarctic</span> circumpolar current.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Taylor, John R; Bachman, Scott; Stamper, Megan; Hosegood, Phil; Adams, Katherine; Sallee, Jean-Baptiste; Torres, Ricardo</p> <p>2018-03-01</p> <p>The eastward-flowing <span class="hlt">Antarctic</span> circumpolar current (ACC) plays a central role in the global <span class="hlt">ocean</span> overturning circulation and facilitates the exchange of water between the <span class="hlt">ocean</span> surface and interior. Submesoscale eddies and fronts with scales between 1 and 10 km are regularly observed in the upper <span class="hlt">ocean</span> and are associated with strong vertical circulations and enhanced stratification. Despite their importance in other locations, comparatively little is known about submesoscales in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. We present results from new observations, models, and theories showing that submesoscales are qualitatively changed by the strong jet associated with the ACC in the Scotia Sea, east of Drake Passage. Growing submesoscale disturbances develop along a dense filament and are transformed into submesoscale Rossby waves, which propagate upstream relative to the eastward jet. Unlike their counterparts in slower currents, the submesoscale Rossby waves do not destroy the underlying frontal structure. The development of submesoscale instabilities leads to strong net subduction of water associated with a dense outcropping filament, and later, the submesoscale Rossby waves are associated with intense vertical circulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5903883','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5903883"><span>Submesoscale Rossby waves on the <span class="hlt">Antarctic</span> circumpolar current</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bachman, Scott; Sallee, Jean-Baptiste</p> <p>2018-01-01</p> <p>The eastward-flowing <span class="hlt">Antarctic</span> circumpolar current (ACC) plays a central role in the global <span class="hlt">ocean</span> overturning circulation and facilitates the exchange of water between the <span class="hlt">ocean</span> surface and interior. Submesoscale eddies and fronts with scales between 1 and 10 km are regularly observed in the upper <span class="hlt">ocean</span> and are associated with strong vertical circulations and enhanced stratification. Despite their importance in other locations, comparatively little is known about submesoscales in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. We present results from new observations, models, and theories showing that submesoscales are qualitatively changed by the strong jet associated with the ACC in the Scotia Sea, east of Drake Passage. Growing submesoscale disturbances develop along a dense filament and are transformed into submesoscale Rossby waves, which propagate upstream relative to the eastward jet. Unlike their counterparts in slower currents, the submesoscale Rossby waves do not destroy the underlying frontal structure. The development of submesoscale instabilities leads to strong net subduction of water associated with a dense outcropping filament, and later, the submesoscale Rossby waves are associated with intense vertical circulations. PMID:29670936</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11493910','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11493910"><span>Palaeoceanography. <span class="hlt">Antarctic</span> stratification and glacial CO2.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Keeling, R F; Visbeck, M</p> <p>2001-08-09</p> <p>One way of accounting for lowered atmospheric carbon dioxide concentrations during Pleistocene glacial periods is by invoking the <span class="hlt">Antarctic</span> stratification hypothesis, which links the reduction in CO2 to greater stratification of <span class="hlt">ocean</span> surface waters around Antarctica. As discussed by Sigman and Boyle, this hypothesis assumes that increased stratification in the <span class="hlt">Antarctic</span> zone (Fig. 1) was associated with reduced upwelling of deep waters around Antarctica, thereby allowing CO2 outgassing to be suppressed by biological production while also allowing biological production to decline, which is consistent with <span class="hlt">Antarctic</span> sediment records. We point out here, however, that the response of <span class="hlt">ocean</span> eddies to increased <span class="hlt">Antarctic</span> stratification can be expected to increase, rather than reduce, the upwelling rate of deep waters around Antarctica. The stratification hypothesis may have difficulty in accommodating eddy feedbacks on upwelling within the constraints imposed by reconstructions of winds and <span class="hlt">Antarctic</span>-zone productivity in glacial periods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22494503','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22494503"><span>Persistent genetic signatures of historic climatic events in an <span class="hlt">Antarctic</span> octopus.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Strugnell, J M; Watts, P C; Smith, P J; Allcock, A L</p> <p>2012-06-01</p> <p>Repeated cycles of glaciation have had major impacts on the distribution of genetic diversity of the <span class="hlt">Antarctic</span> marine fauna. During glacial periods, ice cover limited the amount of benthic habitat on the continental shelf. Conversely, more habitat and possibly altered seaways were available during interglacials when the ice receded and the sea level was higher. We used microsatellites and partial sequences of the mitochondrial cytochrome oxidase 1 gene to examine genetic structure in the direct-developing, endemic <span class="hlt">Southern</span> <span class="hlt">Ocean</span> octopod Pareledone turqueti sampled from a broad range of areas that circumvent Antarctica. We find that, unusually for a species with poor dispersal potential, P. turqueti has a circumpolar distribution and is also found off the islands of South Georgia and Shag Rocks. The overriding pattern of spatial genetic structure can be explained by hydrographic (with <span class="hlt">ocean</span> currents both facilitating and hindering gene flow) and bathymetric features. The <span class="hlt">Antarctic</span> Peninsula region displays a complex population structure, consistent with its varied topographic and oceanographic influences. Genetic similarities between the Ross and Weddell Seas, however, are interpreted as a persistent historic genetic signature of connectivity during the hypothesized Pleistocene West <span class="hlt">Antarctic</span> Ice Sheet collapses. A calibrated molecular clock indicates two major lineages within P. turqueti, a continental lineage and a sub-<span class="hlt">Antarctic</span> lineage, that diverged in the mid-Pliocene with no subsequent gene flow. Both lineages survived subsequent major glacial cycles. Our data are indicative of potential refugia at Shag Rocks and South Georgia and also around the <span class="hlt">Antarctic</span> continent within the Ross Sea, Weddell Sea and off Adélie Land. The mean age of mtDNA diversity within these main continental lineages coincides with Pleistocene glacial cycles. © 2012 Blackwell Publishing Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70033839','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70033839"><span>Pliocene three-dimensional global <span class="hlt">ocean</span> temperature reconstruction</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Dowsett, H.J.; Robinson, M.M.; Foley, K.M.</p> <p>2009-01-01</p> <p>A snapshot of the thermal structure of the mid-Piacenzian <span class="hlt">ocean</span> is obtained by combining the Pliocene Research, Interpretation and Synoptic Mapping Project (PRISM3) multiproxy sea-surface temperature (SST) reconstruction with bottom water tempera-5 ture estimates produced using Mg/Ca paleothermometry. This reconstruction assumes a Pliocene water mass framework similar to that which exists today, with several important modifications. The area of formation of present day North Atlantic Deep Water (NADW) was expanded and extended further north toward the Arctic <span class="hlt">Ocean</span> during the mid-Piacenzian relative to today. This, combined with a deeper Greenland-Scotland Ridge, allowed a greater volume of warmer NADW to enter the Atlantic <span class="hlt">Ocean</span>. In the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, the Polar Front Zone was expanded relative to present day, but shifted closer to the <span class="hlt">Antarctic</span> continent. This, combined with at least seasonal reduction in sea ice extent, resulted in decreased <span class="hlt">Antarctic</span> BottomWater (AABW) production (relative to present day) as well as possible changes in the depth of intermediate wa15 ters. The reconstructed mid-Piacenzian three-dimensional <span class="hlt">ocean</span> was warmer overall than today, and the hypothesized aerial extent of water masses appears to fit the limited stable isotopic data available for this time period. ?? Author(s) 2009.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5324094','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5324094"><span>Variability in sea ice cover and climate elicit sex specific responses in an <span class="hlt">Antarctic</span> predator</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Labrousse, Sara; Sallée, Jean-Baptiste; Fraser, Alexander D.; Massom, Rob A.; Reid, Phillip; Hobbs, William; Guinet, Christophe; Harcourt, Robert; McMahon, Clive; Authier, Matthieu; Bailleul, Frédéric; Hindell, Mark A.; Charrassin, Jean-Benoit</p> <p>2017-01-01</p> <p>Contrasting regional changes in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> sea ice have occurred over the last 30 years with distinct regional effects on ecosystem structure and function. Quantifying how <span class="hlt">Antarctic</span> predators respond to such changes provides the context for predicting how climate variability/change will affect these assemblages into the future. Over an 11-year time-series, we examine how inter-annual variability in sea ice concentration and advance affect the foraging behaviour of a top <span class="hlt">Antarctic</span> predator, the <span class="hlt">southern</span> elephant seal. Females foraged longer in pack ice in years with greatest sea ice concentration and earliest sea ice advance, while males foraged longer in polynyas in years of lowest sea ice concentration. There was a positive relationship between near-surface meridional wind anomalies and female foraging effort, but not for males. This study reveals the complexities of foraging responses to climate forcing by a poleward migratory predator through varying sea ice property and dynamic anomalies. PMID:28233791</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28233791','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28233791"><span>Variability in sea ice cover and climate elicit sex specific responses in an <span class="hlt">Antarctic</span> predator.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Labrousse, Sara; Sallée, Jean-Baptiste; Fraser, Alexander D; Massom, Rob A; Reid, Phillip; Hobbs, William; Guinet, Christophe; Harcourt, Robert; McMahon, Clive; Authier, Matthieu; Bailleul, Frédéric; Hindell, Mark A; Charrassin, Jean-Benoit</p> <p>2017-02-24</p> <p>Contrasting regional changes in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> sea ice have occurred over the last 30 years with distinct regional effects on ecosystem structure and function. Quantifying how <span class="hlt">Antarctic</span> predators respond to such changes provides the context for predicting how climate variability/change will affect these assemblages into the future. Over an 11-year time-series, we examine how inter-annual variability in sea ice concentration and advance affect the foraging behaviour of a top <span class="hlt">Antarctic</span> predator, the <span class="hlt">southern</span> elephant seal. Females foraged longer in pack ice in years with greatest sea ice concentration and earliest sea ice advance, while males foraged longer in polynyas in years of lowest sea ice concentration. There was a positive relationship between near-surface meridional wind anomalies and female foraging effort, but not for males. This study reveals the complexities of foraging responses to climate forcing by a poleward migratory predator through varying sea ice property and dynamic anomalies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/28938-meltwater-input-southern-ocean-during-last-glacial-maximum','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/28938-meltwater-input-southern-ocean-during-last-glacial-maximum"><span>Meltwater input to the <span class="hlt">southern</span> <span class="hlt">ocean</span> during the last glacial maximum</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Shemesh, A.; Burckle, L.H.; Hays, J.D.</p> <p>1994-12-02</p> <p>Three records of oxygen isotopes in biogenic silica from deep-sea sediment cores from the Atlantic and Indian sectors of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> reveal the presence of isotopically depleted diatomaceous opal in sediment from the last glacial maximum. This depletion is attributed to the presence of lids of meltwater that mixed with surface water along certain trajectories in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. An increase in the drainage from Antarctica or extensive northward transport of icebergs are among the main mechanisms that could have produced the increase in meltwater input to the glacial <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Similar isotopic trends were observed in older climaticmore » cycles at the same cores.« less</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeoRL..42..459B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeoRL..42..459B"><span><span class="hlt">Ocean</span> glider observations of iceberg-enhanced biological production in the northwestern Weddell Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Biddle, Louise C.; Kaiser, Jan; Heywood, Karen J.; Thompson, Andrew F.; Jenkins, Adrian</p> <p>2015-01-01</p> <p>Icebergs affect local biological production around Antarctica. We used an <span class="hlt">ocean</span> glider to observe the effects of a large iceberg that was advected by the <span class="hlt">Antarctic</span> Slope Current along the continental slope in the northwestern Weddell Sea in early 2012. The high-resolution glider data reveal a pronounced effect of the iceberg on <span class="hlt">ocean</span> properties, with oxygen concentrations of (13 ± 4) μmol kg-1 higher than levels in surrounding waters, which are most likely due to positive net community production. This response was confined to three areas of water in the direct vicinity of the iceberg track, each no larger than 2 km2. Our findings suggest that icebergs have an impact on <span class="hlt">Antarctic</span> production presumably through local micronutrient injections, on a scale smaller than typical satellite observations of biological production in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28682333','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28682333"><span>West <span class="hlt">Antarctic</span> Ice Sheet retreat driven by Holocene warm water incursions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hillenbrand, Claus-Dieter; Smith, James A; Hodell, David A; Greaves, Mervyn; Poole, Christopher R; Kender, Sev; Williams, Mark; Andersen, Thorbjørn Joest; Jernas, Patrycja E; Elderfield, Henry; Klages, Johann P; Roberts, Stephen J; Gohl, Karsten; Larter, Robert D; Kuhn, Gerhard</p> <p>2017-07-05</p> <p>Glaciological and oceanographic observations coupled with numerical models show that warm Circumpolar Deep Water (CDW) incursions onto the West <span class="hlt">Antarctic</span> continental shelf cause melting of the undersides of floating ice shelves. Because these ice shelves buttress glaciers feeding into them, their <span class="hlt">ocean</span>-induced thinning is driving <span class="hlt">Antarctic</span> ice-sheet retreat today. Here we present a multi-proxy data based reconstruction of variability in CDW inflow to the Amundsen Sea sector, the most vulnerable part of the West <span class="hlt">Antarctic</span> Ice Sheet, during the Holocene epoch (from 11.7 thousand years ago to the present). The chemical compositions of foraminifer shells and benthic foraminifer assemblages in marine sediments indicate that enhanced CDW upwelling, controlled by the latitudinal position of the <span class="hlt">Southern</span> Hemisphere westerly winds, forced deglaciation of this sector from at least 10,400 years ago until 7,500 years ago-when an ice-shelf collapse may have caused rapid ice-sheet thinning further upstream-and since the 1940s. These results increase confidence in the predictive capability of current ice-sheet models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012PrOce..96...93L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012PrOce..96...93L"><span>Population dynamics of Salpa thompsoni near the <span class="hlt">Antarctic</span> Peninsula: Growth rates and interannual variations in reproductive activity (1993-2009)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Loeb, V. J.; Santora, J. A.</p> <p>2012-04-01</p> <p>The salp Salpa thompsoni has exhibited increased abundance in high latitude portions of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in recent decades and is now frequently the numerically dominant zooplankton taxon in the <span class="hlt">Antarctic</span> Peninsula region. The abundance increase of this species in high latitude waters is believed related to <span class="hlt">ocean</span> warming. Due to its continuous filter feeding and production of dense rapidly sinking fecal pellets S. thompsoni is considered to be an important link in the export of particulate carbon from the surface waters. Hence basic information on the life history of this component of the <span class="hlt">Antarctic</span> marine ecosystem is essential for assessing its impact given continued climate warming. Here we cover various aspects of the life history of S. thompsoni collected in the north <span class="hlt">Antarctic</span> Peninsula during annual austral summer surveys of the US <span class="hlt">Antarctic</span> Marine Living Resources (AMLR) Program between 1993 and 2009. We focus on seasonal and interannual variations in the size composition and abundance of the aggregate (sexual) and solitary (asexual) stages. This information is valuable for refining components of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> food web models that explicitly deal with size-structured and life history information on zooplankton. Intraseasonal changes in length-frequency distribution of both stages are used to estimate their growth rates. These average 0.40 mm day-1 for aggregates and 0.23 mm day-1 for solitaries; together these represent ∼7 week and ∼7.5 month generation times, respectively, and a 9 month life cycle (i.e., onset of aggregate production year 1 to aggregate production year 2). Based on the maximum lengths typically found during January-March, the life spans of the aggregate and solitary stages can reach at least ∼5 and ∼15 months, respectively. Length-frequency distributions each year reflect interannual differences in timing of the initiation and peak reproductive output. Interannual differences in the abundance of total salps and proportions of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006DSRI...53..836I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006DSRI...53..836I"><span>Seasonal trends in the pigment and amino acid compositions of sinking particles in biogenic CaCO 3 and SiO 2 dominated regions of the Pacific sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> along 170°W</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ingalls, Anitra E.; Liu, Zhanfei; Lee, Cindy</p> <p>2006-05-01</p> <p>We investigated amino acids and pigments in particles settling through the water column of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and showed that spatial and temporal differences in phytoplankton source and consumer population influence sinking particle composition. Sediment traps were deployed along 170°W from November 1996 to March 1998 as part of the United States Joint Global <span class="hlt">Ocean</span> Flux Study (US JGOFS) <span class="hlt">Antarctic</span> Environment <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Process Study (AESOPS) program. Peak fluxes of amino acids and pigments occurred during austral spring and summer (November-April) and were highest in the <span class="hlt">Antarctic</span> Circumpolar Current (ACC). Compositional changes in pigments and total hydrolyzed amino acids demonstrate how the source of sinking particles varies with latitude and suggest that sinking material was most degraded in relatively diatom-depleted regions and toward the end of the high-flux period (February-March). At the Subantarctic Front, high proportions of pheophytin and β-alanine illustrate the important role of microbes in degradation. Further south at the <span class="hlt">Antarctic</span> Polar Front, glycine, pyropheophorbide, and pheophorbide enrichments reflected a greater contribution of diatoms and greater processing by zooplankton grazers. Even further south in the ACC, enrichments of the diatom pigment fucoxanthin, diatom cell wall indicators glycine and serine, and diatom frustule-bound amino acids suggested the settling of empty frustules and aggregates. Despite being protected by the mineral, diatom-bound amino acids were not preferentially preserved between shallow and deep traps, possibly because of silica dissolution and a relatively small amount of organic carbon remineralization. Our results show that organic matter at diatom-rich stations is removed by mechanisms that do not result in the appearance of organic matter degradation indicators. Recent observations that calcium carbonate has a higher carrying capacity for sinking organic matter than silica may be related to diatom</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5666255','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5666255"><span>Genetic signature of Last Glacial Maximum regional refugia in a circum-<span class="hlt">Antarctic</span> sea spider</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Soler-Membrives, Anna; Linse, Katrin; Miller, Karen J.</p> <p>2017-01-01</p> <p>The evolutionary history of <span class="hlt">Antarctic</span> organisms is becoming increasingly important to understand and manage population trajectories under rapid environmental change. The <span class="hlt">Antarctic</span> sea spider Nymphon australe, with an apparently large population size compared with other sea spider species, is an ideal target to look for molecular signatures of past climatic events. We analysed mitochondrial DNA of specimens collected from the <span class="hlt">Antarctic</span> continent and two <span class="hlt">Antarctic</span> islands (AI) to infer past population processes and understand current genetic structure. Demographic history analyses suggest populations survived in refugia during the Last Glacial Maximum. The high genetic diversity found in the <span class="hlt">Antarctic</span> Peninsula and East <span class="hlt">Antarctic</span> (EA) seems related to multiple demographic contraction–expansion events associated with deep-sea refugia, while the low genetic diversity in the Weddell Sea points to a more recent expansion from a shelf refugium. We suggest the genetic structure of N. australe from AI reflects recent colonization from the continent. At a local level, EA populations reveal generally low genetic differentiation, geographically and bathymetrically, suggesting limited restrictions to dispersal. Results highlight regional differences in demographic histories and how these relate to the variation in intensity of glaciation–deglaciation events around Antarctica, critical for the study of local evolutionary processes. These are valuable data for understanding the remarkable success of <span class="hlt">Antarctic</span> pycnogonids, and how environmental changes have shaped the evolution and diversification of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> benthic biodiversity. PMID:29134072</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017RSOS....470615S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017RSOS....470615S"><span>Genetic signature of Last Glacial Maximum regional refugia in a circum-<span class="hlt">Antarctic</span> sea spider</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Soler-Membrives, Anna; Linse, Katrin; Miller, Karen J.; Arango, Claudia P.</p> <p>2017-10-01</p> <p>The evolutionary history of <span class="hlt">Antarctic</span> organisms is becoming increasingly important to understand and manage population trajectories under rapid environmental change. The <span class="hlt">Antarctic</span> sea spider Nymphon australe, with an apparently large population size compared with other sea spider species, is an ideal target to look for molecular signatures of past climatic events. We analysed mitochondrial DNA of specimens collected from the <span class="hlt">Antarctic</span> continent and two <span class="hlt">Antarctic</span> islands (AI) to infer past population processes and understand current genetic structure. Demographic history analyses suggest populations survived in refugia during the Last Glacial Maximum. The high genetic diversity found in the <span class="hlt">Antarctic</span> Peninsula and East <span class="hlt">Antarctic</span> (EA) seems related to multiple demographic contraction-expansion events associated with deep-sea refugia, while the low genetic diversity in the Weddell Sea points to a more recent expansion from a shelf refugium. We suggest the genetic structure of N. australe from AI reflects recent colonization from the continent. At a local level, EA populations reveal generally low genetic differentiation, geographically and bathymetrically, suggesting limited restrictions to dispersal. Results highlight regional differences in demographic histories and how these relate to the variation in intensity of glaciation-deglaciation events around Antarctica, critical for the study of local evolutionary processes. These are valuable data for understanding the remarkable success of <span class="hlt">Antarctic</span> pycnogonids, and how environmental changes have shaped the evolution and diversification of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> benthic biodiversity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014OcScD..11.2289S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014OcScD..11.2289S"><span>Transient tracer applications in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stöven, T.; Tanhua, T.; Hoppema, M.</p> <p>2014-10-01</p> <p>Transient tracers can be used to constrain the Inverse-Gaussian transit time distribution (IG-TTD) and thus provide information about <span class="hlt">ocean</span> ventilation. Individual transient tracers have different time and application ranges which are defined by their atmospheric history (chronological transient tracers) or their decay rate (radioactive transient tracers). The classification ranges from tracers for highly ventilated water masses, e.g. sulfur hexafluoride (SF6), the decay of Tritium (δ3H) and to some extent also dichlorodifluoromethane (CFC-12) to tracers for less ventilated deep <span class="hlt">ocean</span> basins, e.g. CFC-12, Argon-39 (39Ar) and radiocarbon (14C). The IG-TTD can be empirically constrained by using transient tracer couples with sufficiently different input functions. Each tracer couple has specific characteristics which influence the application limit of the IG-TTD. Here we provide an overview of commonly used transient tracer couples and their validity areas within the IG-TTD by using the concept of tracer age differences (TAD). New measured CFC-12 and SF6 data from a section along 10° E in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in 2012 are presented. These are combined with a similar data set of 1998 along 6° E in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> as well as with 39Ar data from the early 1980s in the western Atlantic <span class="hlt">Ocean</span> and the Weddell Sea for investigating the application limit of the IG-TTD and to analyze changes in ventilation in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. We found that the IG-TTD can be constrained south to 46° S which corresponds to the Subantarctic Front (SAF) denoting the application limit. The constrained IG-TTD north of the SAF shows a slight increase in mean ages between 1998 and 2012 in the upper 1200 m between 42-46° S. The absence of SF6 inhibits ventilation analyses below this depth. The time lag analysis between the 1998 and 2012 data shows an increase in ventilation down to 1000 m and a steady ventilation between 2000 m-bottom south of the SAF between 51-55° S.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27533327','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27533327"><span>At-Sea Distribution and Prey Selection of <span class="hlt">Antarctic</span> Petrels and Commercial Krill Fisheries.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Descamps, Sébastien; Tarroux, Arnaud; Cherel, Yves; Delord, Karine; Godø, Olaf Rune; Kato, Akiko; Krafft, Bjørn A; Lorentsen, Svein-Håkon; Ropert-Coudert, Yan; Skaret, Georg; Varpe, Øystein</p> <p>2016-01-01</p> <p>Commercial fisheries may impact marine ecosystems and affect populations of predators like seabirds. In the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, there is an extensive fishery for <span class="hlt">Antarctic</span> krill Euphausia superba that is projected to increase further. Comparing distribution and prey selection of fishing operations versus predators is needed to predict fishery-related impacts on krill-dependent predators. In this context, it is important to consider not only predators breeding near the fishing grounds but also the ones breeding far away and that disperse during the non-breeding season where they may interact with fisheries. In this study, we first quantified the overlap between the distribution of the <span class="hlt">Antarctic</span> krill fisheries and the distribution of a krill dependent seabird, the <span class="hlt">Antarctic</span> petrel Thalassoica antarctica, during both the breeding and non-breeding season. We tracked birds from the world biggest <span class="hlt">Antarctic</span> petrel colony (Svarthamaren, Dronning Maud Land), located >1000 km from the main fishing areas, during three consecutive seasons. The overall spatial overlap between krill fisheries and <span class="hlt">Antarctic</span> petrels was limited but varied greatly among and within years, and was high in some periods during the non-breeding season. In a second step, we described the length frequency distribution of <span class="hlt">Antarctic</span> krill consumed by <span class="hlt">Antarctic</span> petrels, and compared this with results from fisheries, as well as from diet studies in other krill predators. Krill taken by <span class="hlt">Antarctic</span> petrels did not differ in size from that taken by trawls or from krill taken by most <span class="hlt">Antarctic</span> krill predators. Selectivity for specific <span class="hlt">Antarctic</span> krill stages seems generally low in <span class="hlt">Antarctic</span> predators. Overall, our results show that competition between <span class="hlt">Antarctic</span> petrels and krill fisheries is currently likely negligible. However, if krill fisheries are to increase in the future, competition with the <span class="hlt">Antarctic</span> petrel may occur, even with birds breeding thousands of kilometers away.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4988635','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4988635"><span>At-Sea Distribution and Prey Selection of <span class="hlt">Antarctic</span> Petrels and Commercial Krill Fisheries</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Descamps, Sébastien; Tarroux, Arnaud; Cherel, Yves; Delord, Karine; Godø, Olaf Rune; Kato, Akiko; Krafft, Bjørn A.; Lorentsen, Svein-Håkon; Ropert-Coudert, Yan; Skaret, Georg; Varpe, Øystein</p> <p>2016-01-01</p> <p>Commercial fisheries may impact marine ecosystems and affect populations of predators like seabirds. In the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, there is an extensive fishery for <span class="hlt">Antarctic</span> krill Euphausia superba that is projected to increase further. Comparing distribution and prey selection of fishing operations versus predators is needed to predict fishery-related impacts on krill-dependent predators. In this context, it is important to consider not only predators breeding near the fishing grounds but also the ones breeding far away and that disperse during the non-breeding season where they may interact with fisheries. In this study, we first quantified the overlap between the distribution of the <span class="hlt">Antarctic</span> krill fisheries and the distribution of a krill dependent seabird, the <span class="hlt">Antarctic</span> petrel Thalassoica antarctica, during both the breeding and non-breeding season. We tracked birds from the world biggest <span class="hlt">Antarctic</span> petrel colony (Svarthamaren, Dronning Maud Land), located >1000 km from the main fishing areas, during three consecutive seasons. The overall spatial overlap between krill fisheries and <span class="hlt">Antarctic</span> petrels was limited but varied greatly among and within years, and was high in some periods during the non-breeding season. In a second step, we described the length frequency distribution of <span class="hlt">Antarctic</span> krill consumed by <span class="hlt">Antarctic</span> petrels, and compared this with results from fisheries, as well as from diet studies in other krill predators. Krill taken by <span class="hlt">Antarctic</span> petrels did not differ in size from that taken by trawls or from krill taken by most <span class="hlt">Antarctic</span> krill predators. Selectivity for specific <span class="hlt">Antarctic</span> krill stages seems generally low in <span class="hlt">Antarctic</span> predators. Overall, our results show that competition between <span class="hlt">Antarctic</span> petrels and krill fisheries is currently likely negligible. However, if krill fisheries are to increase in the future, competition with the <span class="hlt">Antarctic</span> petrel may occur, even with birds breeding thousands of kilometers away. PMID:27533327</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ESSD...10..609L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ESSD...10..609L"><span>The <span class="hlt">Ocean</span> Carbon States Database: a proof-of-concept application of cluster analysis in the <span class="hlt">ocean</span> carbon cycle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Latto, Rebecca; Romanou, Anastasia</p> <p>2018-03-01</p> <p>In this paper, we present a database of the basic regimes of the carbon cycle in the <span class="hlt">ocean</span>, the <q><span class="hlt">ocean</span> carbon states</q>, as obtained using a data mining/pattern recognition technique in observation-based as well as model data. The goal of this study is to establish a new data analysis methodology, test it and assess its utility in providing more insights into the regional and temporal variability of the marine carbon cycle. This is important as advanced data mining techniques are becoming widely used in climate and Earth sciences and in particular in studies of the global carbon cycle, where the interaction of physical and biogeochemical drivers confounds our ability to accurately describe, understand, and predict CO2 concentrations and their changes in the major planetary carbon reservoirs. In this proof-of-concept study, we focus on using well-understood data that are based on observations, as well as model results from the NASA Goddard Institute for Space Studies (GISS) climate model. Our analysis shows that <span class="hlt">ocean</span> carbon states are associated with the subtropical-subpolar gyre during the colder months of the year and the tropics during the warmer season in the North Atlantic basin. Conversely, in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, the <span class="hlt">ocean</span> carbon states can be associated with the subtropical and <span class="hlt">Antarctic</span> convergence zones in the warmer season and the coastal <span class="hlt">Antarctic</span> divergence zone in the colder season. With respect to model evaluation, we find that the GISS model reproduces the cold and warm season regimes more skillfully in the North Atlantic than in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and matches the observed seasonality better than the spatial distribution of the regimes. Finally, the <span class="hlt">ocean</span> carbon states provide useful information in the model error attribution. Model air-sea CO2 flux biases in the North Atlantic stem from wind speed and salinity biases in the subpolar region and nutrient and wind speed biases in the subtropics and tropics. Nutrient biases are shown to be most</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMOS53C1057B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMOS53C1057B"><span>Abundant Hydrothermal Venting in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Near 62°S/159°E on the Australian-<span class="hlt">Antarctic</span> Ridge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baker, E. T.; Hahm, D.; Rhee, T. S.; Park, S. H.; Lupton, J. E.; Walker, S. L.; Choi, H.</p> <p>2014-12-01</p> <p>Circum-<span class="hlt">Antarctic</span> Ridges (CARs) comprise almost one-third of the global Mid-<span class="hlt">Ocean</span> Ridge, yet remain terra incognita for hydrothermal activity and chemosynthetic ecosystems. The InterRidge Vents Database lists only 3 confirmed (visualized) and 35 inferred (plume evidence) active sites along the ~21,000 km of CARs. Here, we report on a multi-year effort to locate and characterize hydrothermal activity on two 1st-order segments of the Australian-<span class="hlt">Antarctic</span> Ridge that are perhaps more isolated from other known vent fields than any other vent site on the Mid-<span class="hlt">Ocean</span> Ridge. KR1 is a 300-km-long segment near 62°S/159°E, and KR2 a 90-km-long segment near 60°S/152.5°E. We used profiles collected by Miniature Autonomous Plume Recorders (MAPRs) on rock corers in March and December of 2011 to survey each segment, and an intensive CTD survey in Jan/Feb 2013 to pinpoint sites and sample plumes on KR1. Optical and oxidation-reduction potential (ORP, aka Eh) anomalies indicate multiple active sites on both segments. Seven profiles on KR2 found 3 sites, each separated by ~25 km. Forty profiles on KR1 identified 13 sites, some within a few km of each other. The densest site concentration on KR1 occurred along a relatively inflated, 90-km-long section near the segment center. CTD tows covered 20 km of the eastern, most inflated portion of this area, finding two 6-km-long zones centered near 158.6°E and 158.8°E with multiple plume anomalies. Three ORP anomalies within 50 m of the seafloor indicate precise venting locations. We call this area the Mujin "Misty Harbor" vent field. Vent frequency sharply decreases away from Mujin. 3He/heat ratios determined from 20 plume samples in the Mujin field were mostly <0.015 fM/J, indicative of chronic venting, but 3 samples, 0.021-0.034 fM/J, are ratios typical of a recent eruption. The spatial density of hydrothermal activity along KR1 and KR2 is similar to other intermediate-rate spreading ridges. We calculate the plume incidence (ph) along</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSPO11B..07M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSPO11B..07M"><span>Topographic Enhancement of Vertical Mixing in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mashayek, A.; Ferrari, R. M.; Merrifield, S.; St Laurent, L.</p> <p>2016-02-01</p> <p>Diapycnal turbulent mixing in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is believed to play a role in setting the rate of the <span class="hlt">ocean</span> Meridional Overturning Circulation (MOC), an important element of the global climate system. Whether this role is important, however, depends on the strength of this mixing, which remains poorly qualified on global scale. To address this question, a passive tracer was released upstream of the Drake Passage in 2009 as a part of the Diapycnal and Isopycnal Mixing Experiment in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (DIMES). The mixing was then inferred from the vertical/diapycnal spreading of the tracer. The mixing was also calculated from microstructure measurements of shear and stratification. The diapycnal turbulent mixing inferred from the tracer was found to be an order of magnitude larger than that estimated with the microstructure probes at various locations along the path of the tracer. While the values inferred from tracer imply a key role played by mixing in setting the MOC, those based on localized measurements suggest otherwise. In this work we use a high resolution numerical <span class="hlt">ocean</span> model of the Drake Passage region sampled in the DIMES experiment to explain that the difference between the two estimates arise from the large values of mixing encountered by the tracer, when it flows close to the bottom topography. We conclude that the large mixing close to the <span class="hlt">ocean</span> bottom topography is sufficiently strong to play an important role in setting the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> branch of the MOC below 2 km.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRC..121..327T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRC..121..327T"><span><span class="hlt">Antarctic</span> icebergs distributions 1992-2014</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tournadre, J.; Bouhier, N.; Girard-Ardhuin, F.; Rémy, F.</p> <p>2016-01-01</p> <p>Basal melting of floating ice shelves and iceberg calving constitute the two almost equal paths of freshwater flux between the <span class="hlt">Antarctic</span> ice cap and the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. The largest icebergs (>100 km2) transport most of the ice volume but their basal melting is small compared to their breaking into smaller icebergs that constitute thus the major vector of freshwater. The archives of nine altimeters have been processed to create a database of small icebergs (<8 km2) within open water containing the positions, sizes, and volumes spanning the 1992-2014 period. The intercalibrated monthly ice volumes from the different altimeters have been merged in a homogeneous 23 year climatology. The iceberg size distribution, covering the 0.1-10,000 km2 range, estimated by combining small and large icebergs size measurements follows well a power law of slope -1.52 ± 0.32 close to the -3/2 laws observed and modeled for brittle fragmentation. The global volume of ice and its distribution between the <span class="hlt">ocean</span> basins present a very strong interannual variability only partially explained by the number of large icebergs. Indeed, vast zones of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> free of large icebergs are largely populated by small iceberg drifting over thousands of kilometers. The correlation between the global small and large icebergs volumes shows that small icebergs are mainly generated by large ones breaking. Drifting and trapping by sea ice can transport small icebergs for long period and distances. Small icebergs act as an ice diffuse process along large icebergs trajectories while sea ice trapping acts as a buffer delaying melting.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.C34B..08F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.C34B..08F"><span><span class="hlt">Antarctic</span> Ice Sheet Discharge Driven by Atmosphere-<span class="hlt">Ocean</span> Feedbacks Across the Last Glacial Termination</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fogwill, C. J.; Turney, C. S.; Golledge, N. R.; Etheridge, D. M.; Rubino, M.; Thornton, D.; Baker, A.; Weber, M. E.; Woodward, J.; van Ommen, T. D.; Moy, A. D.; Davies, S. M.; Bird, M. I.; Winter, K.; Munksgaard, N.; Menviel, L.; Rootes, C.; Vohra, J.; Rivera, A.; Cooper, A.</p> <p>2016-12-01</p> <p>Reconstructing the dynamic response of the <span class="hlt">Antarctic</span> ice sheets to warming during the Last Glacial Termination (LGT; 18,000-11,650 yrs ago) allows us to identify ice-climate feedbacks that could improve future projections1,2. Whilst the sequence of events during this period are reasonably well-known, relatively poor chronological control has precluded precise alignment of ice, atmospheric and marine records2, making it difficult to assess relationships between <span class="hlt">Antarctic</span> ice-sheet dynamics, climate change and sea-level rise3-5. Here we present results from a highly-resolved `horizontal ice core'6,7 from the Weddell Sea Embayment, which records millennial-scale ice-sheet dynamics across this extensive sector of Antarctica. Counterintuitively, we find ice-sheet surface drawdown of 600 m across the <span class="hlt">Antarctic</span> Cold Reversal (ACR; 14,600-12,700 yrs ago)5, with stabilisation during the subsequent millennia of atmospheric warming. Earth system and ice-sheet modelling highlights that this response was likely sustained by strong <span class="hlt">ocean</span>-ice feedbacks4,8; however, the drivers remain uncertain. Given the coincidence of the ice-sheet changes recorded with marked shifts in atmospheric circulation9,10,11we suggest that millennial-scale <span class="hlt">Antarctic</span> ice-sheet behaviour was initiated and sustained by global atmospheric teleconnections across the LGT. This has important ramifications ice-sheet stability under contemporary climate change, with changing atmospheric and <span class="hlt">oceanic</span> circulation patterns. 1 Collins, M. et al. in Climate Change 2013: The Physical Science Basis. 2 Weber, M. E. et al. Nature 510, 134-138, (2014). 3 Weaver, A. J., et al., Science 299, 1709-1713, (2003). 4 Golledge, N. R. et al. Nat Commun 5, (2014). 5 Pedro, J. B. et al. Nature Geosci9. 51-55 (2015). 6 Turney, C. S. M. et al. Journal of Quaternary Science 28, 697-704 (2013). 7 Winter, K. et al. Geophys. Res. Lett.43. 5. 2019-2026 (2016). 8 Menviel, L., A. et al., Quaternary Science Reviews 30, 1155-1172 (2011). 9 Hogg</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1715438Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1715438Z"><span>Controls and variability of solute and sedimentary fluxes in <span class="hlt">Antarctic</span> and sub-<span class="hlt">Antarctic</span> Environments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zwolinski, Zbigniew</p> <p>2015-04-01</p> <p>The currently prepared SEDIBUD Book on "Source-to-Sink Fluxes in Undisturbed Cold Environments" (edited by Achim A. Beylich, John C. Dixon and Zbigniew Zwolinski and published by Cambridge University Press) is summarizing and synthesizing the achievements of the International Association of Geomorphologists` (I.A.G./A.I.G.) Working Group SEDIBUD (Sediment Budgets in Cold Environments), which has been active since 2005 (http://www.geomorph.org/wg/wgsb.html). The book comprises five parts. One of them is part about sub-<span class="hlt">Antarctic</span> and <span class="hlt">Antarctic</span> Environments. This part "Sub-<span class="hlt">Antarctic</span> and <span class="hlt">Antarctic</span> Environments" describes two different environments, namely <span class="hlt">oceanic</span> and continental ones. Each part contains results of research on environmental drivers and rates of contemporary solute and sedimentary fluxes in selected sites. Apart from describing the environmental conditions of the whole continent of Antarctica and sub-<span class="hlt">Antarctic</span> islands (Zb.Zwolinski, M.Kejna, A.N.Lastochkin, A.Zhirov, S.Boltramovich) this part of the book characterizes terrestrial polar oases free from multi-year ice and snow covers (Zb.Zwolinski). The detailed results of geoecological and sedimentological research come from different parts of Antarctica. <span class="hlt">Antarctic</span> continental shelf (E.Isla) is an example of sub-<span class="hlt">Antarctic</span> <span class="hlt">oceanic</span> environment. South Shetlands, especially King George Island (Zb.Zwolinski, M.Kejna, G.Rachlewicz, I.Sobota, J.Szpikowski), is an example of sub-<span class="hlt">Antarctic</span> terrestrial environment. <span class="hlt">Antarctic</span> Peninsula (G.Vieira, M.Francelino, J.C.Fernandes) and surroundings of McMurdo Dry Valleys (W.B.Lyons, K.A.Welch, J.Levy, A.Fountain, D.McKnight) are examples of <span class="hlt">Antarctic</span> continental environments. The key goals of the <span class="hlt">Antarctic</span> and sub-<span class="hlt">Antarctic</span> book chapters are following: (i) identify the main environmental drivers and rates of contemporary solute and sedimentary fluxes, and (ii) model possible effects of projected climate change on solute and sedimentary fluxes in cold climate environments</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010100393','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010100393"><span>Variability of <span class="hlt">Antarctic</span> Sea Ice 1979-1998</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zwally, H. Jay; Comiso, Josefino C.; Parkinson, Claire L.; Cavalieri, Donald J.; Gloersen, Per; Koblinsky, Chester J. (Technical Monitor)</p> <p>2001-01-01</p> <p>The principal characteristics of the variability of <span class="hlt">Antarctic</span> sea ice cover as previously described from satellite passive-microwave observations are also evident in a systematically-calibrated and analyzed data set for 20.2 years (1979-1998). The total <span class="hlt">Antarctic</span> sea ice extent (concentration > 15 %) increased by 13,440 +/- 4180 sq km/year (+1.18 +/- 0.37%/decade). The area of sea ice within the extent boundary increased by 16,960 +/- 3,840 sq km/year (+1.96 +/- 0.44%/decade). Regionally, the trends in extent are positive in the Weddell Sea (1.5 +/- 0.9%/decade), Pacific <span class="hlt">Ocean</span> (2.4 +/- 1.4%/decade), and Ross (6.9 +/- 1.1 %/decade) sectors, slightly negative in the Indian <span class="hlt">Ocean</span> (-1.5 +/- 1.8%/decade, and strongly negative in the Bellingshausen-Amundsen Seas sector (-9.5 +/- 1.5%/decade). For the entire ice pack, small ice increases occur in all seasons with the largest increase during autumn. On a regional basis, the trends differ season to season. During summer and fall, the trends are positive or near zero in all sectors except the Bellingshausen-Amundsen Seas sector. During winter and spring, the trends are negative or near zero in all sectors except the Ross Sea, which has positive trends in all seasons. Components of interannual variability with periods of about 3 to 5 years are regionally large, but tend to counterbalance each other in the total ice pack. The interannual variability of the annual mean sea-ice extent is only 1.6% overall, compared to 5% to 9% in each of five regional sectors. Analysis of the relation between regional sea ice extents and spatially-averaged surface temperatures over the ice pack gives an overall sensitivity between winter ice cover and temperature of -0.7% change in sea ice extent per K. For summer, some regional ice extents vary positively with temperature and others negatively. The observed increase in <span class="hlt">Antarctic</span> sea ice cover is counter to the observed decreases in the Arctic. It is also qualitatively consistent with the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950050449&hterms=Ross+1986&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DRoss%2B1986','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950050449&hterms=Ross+1986&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DRoss%2B1986"><span>Spatial patterns in the length of the sea ice season in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, 1979-1986</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Parkinson, Claire L.</p> <p>1994-01-01</p> <p>The length of the sea ice season summarizes in one number the ice coverage conditions for an individual location for an entire year. It becomes a particularly valuable variable when mapped spatially over a large area and examined for regional and interannual differences, as is done here for the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> over the years 1979-1986, using the satellite passive microwave data of the Nimbus 7 scanning multichannel microwave radiometer. Three prominent geographic anomalies in ice season lengths occur consistently in each year of the data set, countering the general tendency toward shorter ice seasons from south to north: (1) in the Weddell Sea the tendency is toward shorter ice seasons from southwest to northeast, reflective of the cyclonic ice/atmosphere/<span class="hlt">ocean</span> circulations in the Weddell Sea region. (2) Directly north of the Ross Ice Shelf anomalously short ice seasons occur, lasting only 245-270 days, in contrast to the perennial ice coverage at comparable latitudes in the <span class="hlt">southern</span> Bellingshausen and Amundsen Seas and in the western Weddell Sea. The short ice season off the Ross Ice Shelf reflects the consistently early opening of the ice cover each spring, under the influence of upwelling along the continental slope and shelf and atmospheric forcing from winds blowing off the <span class="hlt">Antarctic</span> continent. (3) In the <span class="hlt">southern</span> Amundsen Sea, anomalously short ice seasons occur adjacent to the coast, owing to the frequent existence of coastal polynyas off the many small ice shelves bordering the sea. Least squares trends in the ice season lengths over the 1979-1986 period are highly coherent spatially, with overall trends toward shorter ice seasons in the northern Weddell and Bellingshausen seas and toward longer ice seasons in the Ross Sea, around much of East Antarctica, and in a portion of the south central Weddell Sea.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994JGR....9916327P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994JGR....9916327P"><span>Spatial patterns in the length of the sea ice season in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, 1979-1986</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Parkinson, Claire L.</p> <p>1994-08-01</p> <p>The length of the sea ice season summarizes in one number the ice coverage conditions for an individual location for an entire year. It becomes a particularly valuable variable when mapped spatially over a large area and examined for regional and interannual differences, as is done here for the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> over the years 1979-1986, using the satellite passive microwave data of the Nimbus 7 scanning multichannel microwave radiometer. Three prominent geographic anomalies in ice season lengths occur consistently in each year of the data set, countering the general tendency toward shorter ice seasons from south to north: (1) In the Weddell Sea the tendency is toward shorter ice seasons from southwest to northeast, reflective of the cyclonic ice/atmosphere/<span class="hlt">ocean</span> circulations in the Weddell Sea region. (2) Directly north of the Ross Ice Shelf anomalously short ice seasons occur, lasting only 245-270 days, in contrast to the perennial ice coverage at comparable latitudes in the <span class="hlt">southern</span> Bellingshausen and Amundsen Seas and in the western Weddell Sea. The short ice season off the Ross Ice Shelf reflects the consistently early opening of the ice cover each spring, under the influence of upwelling along the continental slope and shelf and atmospheric forcing from winds blowing off the <span class="hlt">Antarctic</span> continent. (3) In the <span class="hlt">southern</span> Amundsen Sea, anomalously short ice seasons occur adjacent to the coast, owing to the frequent existence of coastal polynyas off the many small ice shelves bordering the sea. Least squares trends in the ice season lengths over the 1979-1986 period are highly coherent spatially, with overall trends toward shorter ice seasons in the northern Weddell and Bellingshausen seas and toward longer ice seasons in the Ross Sea, around much of East Antarctica, and in a portion of the south central Weddell Sea.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMPP11B1348F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMPP11B1348F"><span>Enhanced deep <span class="hlt">ocean</span> ventilation and oxygenation with global warming</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Froelicher, T. L.; Jaccard, S.; Dunne, J. P.; Paynter, D.; Gruber, N.</p> <p>2014-12-01</p> <p>Twenty-first century coupled climate model simulations, observations from the recent past, and theoretical arguments suggest a consistent trend towards warmer <span class="hlt">ocean</span> temperatures and fresher polar surface <span class="hlt">oceans</span> in response to increased radiative forcing resulting in increased upper <span class="hlt">ocean</span> stratification and reduced ventilation and oxygenation of the deep <span class="hlt">ocean</span>. Paleo-proxy records of the warming at the end of the last ice age, however, suggests a different outcome, namely a better ventilated and oxygenated deep <span class="hlt">ocean</span> with global warming. Here we use a four thousand year global warming simulation from a comprehensive Earth System Model (GFDL ESM2M) to show that this conundrum is a consequence of different rates of warming and that the deep <span class="hlt">ocean</span> is actually better ventilated and oxygenated in a future warmer equilibrated climate consistent with paleo-proxy records. The enhanced deep <span class="hlt">ocean</span> ventilation in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> occurs in spite of increased positive surface buoyancy fluxes and a constancy of the <span class="hlt">Southern</span> Hemisphere westerly winds - circumstances that would otherwise be expected to lead to a reduction in deep <span class="hlt">ocean</span> ventilation. This ventilation recovery occurs through a global scale interaction of the Atlantic Meridional Overturning Circulation undergoing a multi-centennial recovery after an initial century of transient decrease and transports salinity-rich waters inform the subtropical surface <span class="hlt">ocean</span> to the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> interior on multi-century timescales. The subsequent upwelling of salinity-rich waters in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> strips away the freshwater cap that maintains vertical stability and increases open <span class="hlt">ocean</span> convection and the formation of <span class="hlt">Antarctic</span> Bottom Waters. As a result, the global <span class="hlt">ocean</span> oxygen content and the nutrient supply from the deep <span class="hlt">ocean</span> to the surface are higher in a warmer <span class="hlt">ocean</span>. The implications for past and future changes in <span class="hlt">ocean</span> heat and carbon storage will be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5319791','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5319791"><span>Modelling the effects of environmental conditions on the acoustic occurrence and behaviour of <span class="hlt">Antarctic</span> blue whales</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Shabangu, Fannie W.; Yemane, Dawit; Stafford, Kathleen M.; Ensor, Paul; Findlay, Ken P.</p> <p>2017-01-01</p> <p>Harvested to perilously low numbers by commercial whaling during the past century, the large scale response of <span class="hlt">Antarctic</span> blue whales Balaenoptera musculus intermedia to environmental variability is poorly understood. This study uses acoustic data collected from 586 sonobuoys deployed in the austral summers of 1997 through 2009, south of 38°S, coupled with visual observations of blue whales during the IWC SOWER line-transect surveys. The characteristic Z-call and D-call of <span class="hlt">Antarctic</span> blue whales were detected using an automated detection template and visual verification method. Using a random forest model, we showed the environmental preferences pattern, spatial occurrence and acoustic behaviour of <span class="hlt">Antarctic</span> blue whales. Distance to the <span class="hlt">southern</span> boundary of the <span class="hlt">Antarctic</span> Circumpolar Current (SBACC), latitude and distance from the nearest <span class="hlt">Antarctic</span> shores were the main geographic predictors of blue whale call occurrence. Satellite-derived sea surface height, sea surface temperature, and productivity (chlorophyll-a) were the most important environmental predictors of blue whale call occurrence. Call rates of D-calls were strongly predicted by the location of the SBACC, latitude and visually detected number of whales in an area while call rates of Z-call were predicted by the SBACC, latitude and longitude. Satellite-derived sea surface height, wind stress, wind direction, water depth, sea surface temperatures, chlorophyll-a and wind speed were important environmental predictors of blue whale call rates in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Blue whale call occurrence and call rates varied significantly in response to inter-annual and long term variability of those environmental predictors. Our results identify the response of <span class="hlt">Antarctic</span> blue whales to inter-annual variability in environmental conditions and highlighted potential suitable habitats for this population. Such emerging knowledge about the acoustic behaviour, environmental and habitat preferences of <span class="hlt">Antarctic</span> blue whales is</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28222124','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28222124"><span>Modelling the effects of environmental conditions on the acoustic occurrence and behaviour of <span class="hlt">Antarctic</span> blue whales.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shabangu, Fannie W; Yemane, Dawit; Stafford, Kathleen M; Ensor, Paul; Findlay, Ken P</p> <p>2017-01-01</p> <p>Harvested to perilously low numbers by commercial whaling during the past century, the large scale response of <span class="hlt">Antarctic</span> blue whales Balaenoptera musculus intermedia to environmental variability is poorly understood. This study uses acoustic data collected from 586 sonobuoys deployed in the austral summers of 1997 through 2009, south of 38°S, coupled with visual observations of blue whales during the IWC SOWER line-transect surveys. The characteristic Z-call and D-call of <span class="hlt">Antarctic</span> blue whales were detected using an automated detection template and visual verification method. Using a random forest model, we showed the environmental preferences pattern, spatial occurrence and acoustic behaviour of <span class="hlt">Antarctic</span> blue whales. Distance to the <span class="hlt">southern</span> boundary of the <span class="hlt">Antarctic</span> Circumpolar Current (SBACC), latitude and distance from the nearest <span class="hlt">Antarctic</span> shores were the main geographic predictors of blue whale call occurrence. Satellite-derived sea surface height, sea surface temperature, and productivity (chlorophyll-a) were the most important environmental predictors of blue whale call occurrence. Call rates of D-calls were strongly predicted by the location of the SBACC, latitude and visually detected number of whales in an area while call rates of Z-call were predicted by the SBACC, latitude and longitude. Satellite-derived sea surface height, wind stress, wind direction, water depth, sea surface temperatures, chlorophyll-a and wind speed were important environmental predictors of blue whale call rates in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Blue whale call occurrence and call rates varied significantly in response to inter-annual and long term variability of those environmental predictors. Our results identify the response of <span class="hlt">Antarctic</span> blue whales to inter-annual variability in environmental conditions and highlighted potential suitable habitats for this population. Such emerging knowledge about the acoustic behaviour, environmental and habitat preferences of <span class="hlt">Antarctic</span> blue whales is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRC..122.1608P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRC..122.1608P"><span>The <span class="hlt">ocean</span> mixed layer under <span class="hlt">Southern</span> <span class="hlt">Ocean</span> sea-ice: Seasonal cycle and forcing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pellichero, Violaine; Sallée, Jean-Baptiste; Schmidtko, Sunke; Roquet, Fabien; Charrassin, Jean-Benoît</p> <p>2017-02-01</p> <p>The <span class="hlt">oceanic</span> mixed layer is the gateway for the exchanges between the atmosphere and the <span class="hlt">ocean</span>; in this layer, all hydrographic <span class="hlt">ocean</span> properties are set for months to millennia. A vast area of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is seasonally capped by sea-ice, which alters the characteristics of the <span class="hlt">ocean</span> mixed layer. The interaction between the <span class="hlt">ocean</span> mixed layer and sea-ice plays a key role for water mass transformation, the carbon cycle, sea-ice dynamics, and ultimately for the climate as a whole. However, the structure and characteristics of the under-ice mixed layer are poorly understood due to the sparseness of in situ observations and measurements. In this study, we combine distinct sources of observations to overcome this lack in our understanding of the polar regions. Working with elephant seal-derived, ship-based, and Argo float observations, we describe the seasonal cycle of the <span class="hlt">ocean</span> mixed-layer characteristics and stability of the <span class="hlt">ocean</span> mixed layer over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and specifically under sea-ice. Mixed-layer heat and freshwater budgets are used to investigate the main forcing mechanisms of the mixed-layer seasonal cycle. The seasonal variability of sea surface salinity and temperature are primarily driven by surface processes, dominated by sea-ice freshwater flux for the salt budget and by air-sea flux for the heat budget. Ekman advection, vertical diffusivity, and vertical entrainment play only secondary roles. Our results suggest that changes in regional sea-ice distribution and annual duration, as currently observed, widely affect the buoyancy budget of the underlying mixed layer, and impact large-scale water mass formation and transformation with far reaching consequences for <span class="hlt">ocean</span> ventilation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1919339M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1919339M"><span>Water masses transform at mid-depths over the <span class="hlt">Antarctic</span> Continental Slope</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mead Silvester, Jess; Lenn, Yueng-Djern; Polton, Jeffrey; Phillips, Helen E.; Morales Maqueda, Miguel</p> <p>2017-04-01</p> <p>The Meridional Overturning Circulation (MOC) controls the <span class="hlt">oceans</span>' latitudinal heat distribution, helping to regulate the Earth's climate. The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is the primary place where cool, deep waters return to the surface to complete this global circulation. While water mass transformations intrinsic to this process predominantly take place at the surface following upwelling, recent studies implicate vertical mixing in allowing transformation at mid-depths over the <span class="hlt">Antarctic</span> continental slope. We deployed an EM-Apex float near Elephant Island, north of the <span class="hlt">Antarctic</span> Peninsula's tip, to profile along the slope and use potential vorticity to diagnose observed instabilities. The float captures direct heat exchange between a lens of Upper Circumpolar Deep Water (UCDW) and surrounding Lower Circumpolar Deep Waters (LCDW) at mid-depths and over the course of several days. Heat fluxes peak across the top and bottom boundaries of the UCDW lens and peak diffusivities across the bottom boundary are associated with shear instability. Estimates of diffusivity from shear-strain finestructure parameterisation and heat fluxes are found to be in reasonable agreement. The two-dimensional Ertel potential vorticity is elevated both inside the UCDW lens and along its bottom boundary, with a strong contribution from the shear term in these regions and instabilities are associated with gravitational and symmetric forcing. Thus, shear instabilities are driving turbulent mixing across the lower boundary between these two water masses, leading to the observed heat exchange and transformation at mid-depths over the <span class="hlt">Antarctic</span> continental slope. This has implications for our understanding of the rates of upwelling and <span class="hlt">ocean</span>-atmosphere exchanges of heat and carbon at this critical location.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ERL....13e4024S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ERL....13e4024S"><span>Tropospheric jet response to <span class="hlt">Antarctic</span> ozone depletion: An update with Chemistry-Climate Model Initiative (CCMI) models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Son, Seok-Woo; Han, Bo-Reum; Garfinkel, Chaim I.; Kim, Seo-Yeon; Park, Rokjin; Abraham, N. Luke; Akiyoshi, Hideharu; Archibald, Alexander T.; Butchart, N.; Chipperfield, Martyn P.; Dameris, Martin; Deushi, Makoto; Dhomse, Sandip S.; Hardiman, Steven C.; Jöckel, Patrick; Kinnison, Douglas; Michou, Martine; Morgenstern, Olaf; O’Connor, Fiona M.; Oman, Luke D.; Plummer, David A.; Pozzer, Andrea; Revell, Laura E.; Rozanov, Eugene; Stenke, Andrea; Stone, Kane; Tilmes, Simone; Yamashita, Yousuke; Zeng, Guang</p> <p>2018-05-01</p> <p>The <span class="hlt">Southern</span> Hemisphere (SH) zonal-mean circulation change in response to <span class="hlt">Antarctic</span> ozone depletion is re-visited by examining a set of the latest model simulations archived for the Chemistry-Climate Model Initiative (CCMI) project. All models reasonably well reproduce <span class="hlt">Antarctic</span> ozone depletion in the late 20th century. The related SH-summer circulation changes, such as a poleward intensification of westerly jet and a poleward expansion of the Hadley cell, are also well captured. All experiments exhibit quantitatively the same multi-model mean trend, irrespective of whether the <span class="hlt">ocean</span> is coupled or prescribed. Results are also quantitatively similar to those derived from the Coupled Model Intercomparison Project phase 5 (CMIP5) high-top model simulations in which the stratospheric ozone is mostly prescribed with monthly- and zonally-averaged values. These results suggest that the ozone-hole-induced SH-summer circulation changes are robust across the models irrespective of the specific chemistry-atmosphere-<span class="hlt">ocean</span> coupling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GBioC..30.1069K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GBioC..30.1069K"><span>Enzyme-level interconversion of nitrate and nitrite in the fall mixed layer of the <span class="hlt">Antarctic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kemeny, P. C.; Weigand, M. A.; Zhang, R.; Carter, B. R.; Karsh, K. L.; Fawcett, S. E.; Sigman, D. M.</p> <p>2016-07-01</p> <p>In the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, the nitrogen (N) isotopes of organic matter and the N and oxygen (O) isotopes of nitrate (NO3-) have been used to investigate NO3- assimilation and N cycling in the summertime period of phytoplankton growth, both today and in the past. However, recent studies indicate the significance of processes in other seasons for producing the annual cycle of N isotope changes. This study explores the impact of fall conditions on the 15N/14N (δ15N) and 18O/16O (δ18O) of NO3- and nitrite (NO2-) in the Pacific <span class="hlt">Antarctic</span> Zone using depth profiles from late summer/fall of 2014. In the mixed layer, the δ15N and δ18O of NO3- + NO2- increase roughly equally, as expected for NO3- assimilation; however, the δ15N of NO3--only (measured after NO2- removal) increases more than does NO3--only δ18O. Differencing indicates that NO2- has an extremely low δ15N, often < -70‰ versus air. These observations are consistent with the expression of an equilibrium N isotope effect between NO3- and NO2-, likely due to enzymatic NO3--NO2- interconversion. Specifically, we propose reversibility of the nitrite oxidoreductase (NXR) enzyme of nitrite oxidizers that, having been entrained from the subsurface during late summer mixed layer deepening, are inhibited by light. Our interpretation suggests a role for NO3--NO2- interconversion where nitrifiers are transported into environments that discourage NO2- oxidation. This may apply to surface regions with upwelling, such as the summertime <span class="hlt">Antarctic</span>. It may also apply to oxygen-deficient zones, where NXR-catalyzed interconversion may explain previously reported evidence of NO2- oxidation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017NatCo...814499H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NatCo...814499H"><span>Climatically sensitive transfer of iron to maritime <span class="hlt">Antarctic</span> ecosystems by surface runoff</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hodson, Andy; Nowak, Aga; Sabacka, Marie; Jungblut, Anne; Navarro, Francisco; Pearce, David; Ávila-Jiménez, María Luisa; Convey, Peter; Vieira, Gonçalo</p> <p>2017-02-01</p> <p>Iron supplied by glacial weathering results in pronounced hotspots of biological production in an otherwise iron-limited <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Ecosystem. However, glacial iron inputs are thought to be dominated by icebergs. Here we show that surface runoff from three island groups of the maritime <span class="hlt">Antarctic</span> exports more filterable (<0.45 μm) iron (6-81 kg km-2 a-1) than icebergs (0.0-1.2 kg km-2 a-1). Glacier-fed streams also export more acid-soluble iron (27.0-18,500 kg km-2 a-1) associated with suspended sediment than icebergs (0-241 kg km-2 a-1). Significant fluxes of filterable and sediment-derived iron (1-10 Gg a-1 and 100-1,000 Gg a-1, respectively) are therefore likely to be delivered by runoff from the <span class="hlt">Antarctic</span> continent. Although estuarine removal processes will greatly reduce their availability to coastal ecosystems, our results clearly indicate that riverine iron fluxes need to be accounted for as the volume of <span class="hlt">Antarctic</span> melt increases in response to 21st century climate change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/2007/1047/srp/srp024/of2007-1047srp024.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/2007/1047/srp/srp024/of2007-1047srp024.pdf"><span>Abrupt turnover in calcareous-nannoplankton assemblages across the Paleocene/Eocene Thermal Maximum: implications for surface-water oligotrophy over the Kerguelen Plateau, <span class="hlt">Southern</span> Indian <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Jiang, Shijun; Wise, Sherwood W.</p> <p>2007-01-01</p> <p><span class="hlt">Ocean</span> Drilling Program (ODP) Core Section 183-1135A-25R-4 from the Kerguelen Plateau in the Indian <span class="hlt">Ocean</span> sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> represents only the second complete, expanded sequence through the Paleocene/Eocene Thermal Maximum (PETM; ~55 Ma) recovered from <span class="hlt">Antarctic</span> waters. Calcareous nannoplankton at this site underwent an abrupt, fundamental turnover across the PETM as defined by a carbon isotope excursion. Although Chiasmolithus, Discoaster, and Fasciculithus exponentially increase in abundance at the onset, the former abruptly drops but then rapidly recovers, whereas the latter two taxa show opposite trends due to surface-water oligotrophy. These observations confirm previous results from ODP Site 690 on Maud Rise. The elevated pCO2 that accompanied the PETM caused a shoaling of the lysocline and carbonate compensation depth, leading to intensive dissolution of susceptible holococcoliths and poor preservation of the assemblages. Similarities and contrasts between the results of this study and previous work from open-<span class="hlt">ocean</span> sites and shelf margins further demonstrate that the response to the PETM was consistent in open-<span class="hlt">ocean</span> environments, but could be localized on continental shelves where nutrient regimes depend on the local geologic setting and oceanographic conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002DSRII..49..869C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002DSRII..49..869C"><span>Mesozooplankton distribution and grazing during the productive season in the Northwest <span class="hlt">Antarctic</span> Peninsula (FRUELA cruises)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cabal, Jesús A.; Alvarez-Marqués, Florentina; Acuña, José L.; Quevedo, Mario; Gonzalez-Quirós, Rafael; Huskin, Ignacio; Fernández, Diego; del Valle, Carlos Rodriguez; Anadón, Ricardo</p> <p></p> <p>Mesozooplankton distribution and community structure in the Bellinghausen-Bransfield sector of the <span class="hlt">Antarctic</span> <span class="hlt">Ocean</span> were investigated during the FRUELA cruises (December 1995-February 1996). Total mesozooplankton biomass ranged between 0.015 and 1.43 g C m -2. Biomass was higher in the <span class="hlt">Southern</span> boundary of the <span class="hlt">Antarctic</span> Circumpolar Current (SbyACC) area and in coastal waters of the <span class="hlt">Antarctic</span> Peninsula. Total mesozooplankton abundance ranged from 0.4×10 3 to 1.3×10 5 individuals m -2, of which 41.6-99.5% corresponded to copepods, mainly families Oithonidae, Oncaeidae, Pseudocalanidae, Calanidae and Metrididae. There was no evidence of coupling between mesoscale physical features and biomass or community structure. While coastal stations mainly at the Gerlache Strait remained in a highly productive state through the spring-summer, <span class="hlt">oceanic</span> stations experienced a marked shift from a productive condition during FRUELA 95 to a low biomass, pteropod-dominated situation during FRUELA 96, possibly due to changing weather conditions. The median ingestion rates of herbivorous crustaceans during the FRUELA cruises were 0.7 mg Chl a m -2 day -1. Measured ingestion rates represented only 0.1% of the chlorophyll standing stock or 10% of the daily primary production. Thus, crustacean mesozooplankton had little control on the development of phytoplankton blooms in the area.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSPC14D2096T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSPC14D2096T"><span>Birth, life and death of an Anticyclonic eddy in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Torres, R.; Sallee, J. B.; Schwarz, J.; Hosegood, P. J.; Taylor, J. R.; Adams, K.; Bachman, S.; Stamper, M. A.</p> <p>2016-02-01</p> <p>The <span class="hlt">Antarctic</span> Circumpolar Current (ACC) is a climatically relevant frontal structure of global importance, which regularly develops instabilities growing into meanders, and eventually evolving into long-lived anticyclonic eddies. These eddies exhibit sustained primary productivity that can last several months fuelled by local resupply of nutrients. During April-May 2015 we conducted an intensive field experiment in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> where we sampled and tracked an ACC meander as it developed into an eddy and later vanished some 90 days later. The physical characteristics of the meander and eddy were observed with a combination of high resolution hydrography, ADCP and turbulence observations, in addition to biogeochemical observations of nutrients and phytoplankton. The life and death of the eddy was subsequently tracked through Argo, BIO-Argo Lagrangian profilers and remote sensing. In this presentation we will use observations and ecosystem modelling to discuss the physical processes that sustain the observed high Chlorophyll levels in the eddy and explore how the eddy evolution impacts the rate of nutrient supply and how this translates into the observed changes in chlorophyll. We will discuss the relevance of eddy formation to Chlorophyll and productivity in the region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1915171N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1915171N"><span><span class="hlt">Southern</span> <span class="hlt">Ocean</span> coccolithophore biogeography - controlling factors and implications for global biogeochemical cycles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nissen, Cara; Vogt, Meike; Münnich, Matthias; Gruber, Nicolas</p> <p>2017-04-01</p> <p><span class="hlt">Southern</span> <span class="hlt">Ocean</span> phytoplankton biogeography is important for the biogeochemical cycling of carbon, silicate, and the transport of macronutrients to lower latitudes. With the discovery of the "Great Calcite Belt" (GBC), revealing an unexpectedly high prevalence of calcifying phytoplankton in the subtropical frontal region between 40-55°S, the relative importance of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> coccolithophores for phytoplankton biomass, net primary productivity and the carbon cycle need to be revisited. Using a regional high-resolution model with an embedded ecosystem module (ROMS-BEC) for the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (24-78°S) that has been extended to include an explicit representation of coccolithophores, we assess the environmental drivers of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> coccolithophore biogeography over the course of the growing season. We thereby focus on biotic interactions and the relative importance of top-down (grazing) versus bottom-up factors (light, nutrient, temperature) controlling growth and abundance. In our simulation, coccolithophores are an important member of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> phytoplankton community, contributing 13% to annually integrated net primary productivity south of 30°S. We estimate the integrated annual calcification rate to account for 40% of the satellite derived global estimate. Modeled coccolithophore biomass is highest in February and March in a latitudinal band between 40-55°S, when diatoms become heavily silicate limited. This region is characterized by a number of divergent fronts with a low Si:Fe ratio of waters supplied to the mixed layer, supporting an increased growth of coccolithophores at the expense of diatoms. We find top down controls to be the major control on the relative abundance of diatoms and coccolithophores in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. We perform iron and silicate fertilization experiments to assess the effects of changed nutrient availability on coccolithophore abundance in the GCB. We find that changes in nutrient stoichiometry significantly alter</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24889624','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24889624"><span><span class="hlt">Antarctic</span> sea ice control on <span class="hlt">ocean</span> circulation in present and glacial climates.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ferrari, Raffaele; Jansen, Malte F; Adkins, Jess F; Burke, Andrea; Stewart, Andrew L; Thompson, Andrew F</p> <p>2014-06-17</p> <p>In the modern climate, the <span class="hlt">ocean</span> below 2 km is mainly filled by waters sinking into the abyss around Antarctica and in the North Atlantic. Paleoproxies indicate that waters of North Atlantic origin were instead absent below 2 km at the Last Glacial Maximum, resulting in an expansion of the volume occupied by <span class="hlt">Antarctic</span> origin waters. In this study we show that this rearrangement of deep water masses is dynamically linked to the expansion of summer sea ice around Antarctica. A simple theory further suggests that these deep waters only came to the surface under sea ice, which insulated them from atmospheric forcing, and were weakly mixed with overlying waters, thus being able to store carbon for long times. This unappreciated link between the expansion of sea ice and the appearance of a voluminous and insulated water mass may help quantify the <span class="hlt">ocean</span>'s role in regulating atmospheric carbon dioxide on glacial-interglacial timescales. Previous studies pointed to many independent changes in <span class="hlt">ocean</span> physics to account for the observed swings in atmospheric carbon dioxide. Here it is shown that many of these changes are dynamically linked and therefore must co-occur.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMOS43B2057M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMOS43B2057M"><span>Understanding the recent changes in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> carbon cycle: A multidisciplinary approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Manizza, M.; Kahru, M.; Menemenlis, D.; Nevison, C. D.; Mitchell, B. G.; Keeling, R. F.</p> <p>2016-12-01</p> <p>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> represents a key area of the global <span class="hlt">ocean</span> for the uptake of the CO2 originating from fossil fuels emissions. In these waters, cold temperatures combined with high rates of biological production drive the carbon uptake that accounts for about one-third of the global <span class="hlt">ocean</span> uptake.Recent studies showed that changes in the <span class="hlt">Southern</span> Annular Mode (SAM) index, mainly a proxy of the intensity of westerly winds, had a significant impact on the temporal variability of the CO2 uptake in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. In order to shed light on this problem we propose to use both satellite-derived estimates of <span class="hlt">ocean</span> productivity and carbon export in combinations of <span class="hlt">ocean</span> physical and biogeochemical state estimates focusing on the 2006-2013 period. While the estimates of carbon fixation and export based on remote sensing will provide key information on the spatial and temporal variations of the biological carbon pump, the <span class="hlt">ocean</span> state estimates will provide additional information on physical and carbon cycle processes, including the air-sea CO2 fluxes of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in the 2006-2013 period where model solutions have been optimized.These physical estimates will be used to force an <span class="hlt">ocean</span> biogeochemical model (ECCO2-Darwin) that will compute the CO2 uptake for each year. The physical model, forced with optimized atmospheric forcing, aims to realistically simulate interannual <span class="hlt">ocean</span> climate variability that drives changes in both physical and biogeochemical processes ultimately impacting the carbon uptake of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, and potentially responding to the SAM index variations.Although in this study great emphasis is given to the role of physical climate variations at driving the CO2 uptake of these polar waters, we will integrate model results with estimates from remote sensing techniques to better understand role of the biological carbon pump and its variability potentially responding to the SAM index changes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PNAS..115.2687V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PNAS..115.2687V"><span>Strong control of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> cloud reflectivity by ice-nucleating particles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vergara-Temprado, Jesús; Miltenberger, Annette K.; Furtado, Kalli; Grosvenor, Daniel P.; Shipway, Ben J.; Hill, Adrian A.; Wilkinson, Jonathan M.; Field, Paul R.; Murray, Benjamin J.; Carslaw, Ken S.</p> <p>2018-03-01</p> <p>Large biases in climate model simulations of cloud radiative properties over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> cause large errors in modeled sea surface temperatures, atmospheric circulation, and climate sensitivity. Here, we combine cloud-resolving model simulations with estimates of the concentration of ice-nucleating particles in this region to show that our simulated <span class="hlt">Southern</span> <span class="hlt">Ocean</span> clouds reflect far more radiation than predicted by global models, in agreement with satellite observations. Specifically, we show that the clouds that are most sensitive to the concentration of ice-nucleating particles are low-level mixed-phase clouds in the cold sectors of extratropical cyclones, which have previously been identified as a main contributor to the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> radiation bias. The very low ice-nucleating particle concentrations that prevail over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> strongly suppress cloud droplet freezing, reduce precipitation, and enhance cloud reflectivity. The results help explain why a strong radiation bias occurs mainly in this remote region away from major sources of ice-nucleating particles. The results present a substantial challenge to climate models to be able to simulate realistic ice-nucleating particle concentrations and their effects under specific meteorological conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29490918','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29490918"><span>Strong control of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> cloud reflectivity by ice-nucleating particles.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vergara-Temprado, Jesús; Miltenberger, Annette K; Furtado, Kalli; Grosvenor, Daniel P; Shipway, Ben J; Hill, Adrian A; Wilkinson, Jonathan M; Field, Paul R; Murray, Benjamin J; Carslaw, Ken S</p> <p>2018-03-13</p> <p>Large biases in climate model simulations of cloud radiative properties over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> cause large errors in modeled sea surface temperatures, atmospheric circulation, and climate sensitivity. Here, we combine cloud-resolving model simulations with estimates of the concentration of ice-nucleating particles in this region to show that our simulated <span class="hlt">Southern</span> <span class="hlt">Ocean</span> clouds reflect far more radiation than predicted by global models, in agreement with satellite observations. Specifically, we show that the clouds that are most sensitive to the concentration of ice-nucleating particles are low-level mixed-phase clouds in the cold sectors of extratropical cyclones, which have previously been identified as a main contributor to the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> radiation bias. The very low ice-nucleating particle concentrations that prevail over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> strongly suppress cloud droplet freezing, reduce precipitation, and enhance cloud reflectivity. The results help explain why a strong radiation bias occurs mainly in this remote region away from major sources of ice-nucleating particles. The results present a substantial challenge to climate models to be able to simulate realistic ice-nucleating particle concentrations and their effects under specific meteorological conditions. Copyright © 2018 the Author(s). Published by PNAS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5856555','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5856555"><span>Strong control of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> cloud reflectivity by ice-nucleating particles</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Miltenberger, Annette K.; Furtado, Kalli; Grosvenor, Daniel P.; Shipway, Ben J.; Hill, Adrian A.; Wilkinson, Jonathan M.; Field, Paul R.</p> <p>2018-01-01</p> <p>Large biases in climate model simulations of cloud radiative properties over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> cause large errors in modeled sea surface temperatures, atmospheric circulation, and climate sensitivity. Here, we combine cloud-resolving model simulations with estimates of the concentration of ice-nucleating particles in this region to show that our simulated <span class="hlt">Southern</span> <span class="hlt">Ocean</span> clouds reflect far more radiation than predicted by global models, in agreement with satellite observations. Specifically, we show that the clouds that are most sensitive to the concentration of ice-nucleating particles are low-level mixed-phase clouds in the cold sectors of extratropical cyclones, which have previously been identified as a main contributor to the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> radiation bias. The very low ice-nucleating particle concentrations that prevail over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> strongly suppress cloud droplet freezing, reduce precipitation, and enhance cloud reflectivity. The results help explain why a strong radiation bias occurs mainly in this remote region away from major sources of ice-nucleating particles. The results present a substantial challenge to climate models to be able to simulate realistic ice-nucleating particle concentrations and their effects under specific meteorological conditions. PMID:29490918</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoRL..44.9449H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoRL..44.9449H"><span>Connecting tropical climate change with <span class="hlt">Southern</span> <span class="hlt">Ocean</span> heat uptake</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hwang, Yen-Ting; Xie, Shang-Ping; Deser, Clara; Kang, Sarah M.</p> <p>2017-09-01</p> <p>Under increasing greenhouse gas forcing, climate models project tropical warming that is greater in the Northern than the <span class="hlt">Southern</span> Hemisphere, accompanied by a reduction in the northeast trade winds and a strengthening of the southeast trades. While the <span class="hlt">ocean</span>-atmosphere coupling indicates a positive feedback, what triggers the coupled asymmetry and favors greater warming in the northern tropics remains unclear. Far away from the tropics, the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (SO) has been identified as the major region of <span class="hlt">ocean</span> heat uptake. Beyond its local effect on the magnitude of sea surface warming, we show by idealized modeling experiments in a coupled slab <span class="hlt">ocean</span> configuration that enhanced SO heat uptake has a profound global impact. This SO-to-tropics connection is consistent with southward atmospheric energy transport across the equator. Enhanced SO heat uptake results in a zonally asymmetric La-Nina-like pattern of sea surface temperature change that not only affects tropical precipitation but also has influences on the Asian and North American monsoons.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1914547S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1914547S"><span>The role of internal variability for decadal carbon uptake anomalies in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Spring, Aaron; Hi, Hongmei; Ilyina, Tatiana</p> <p>2017-04-01</p> <p>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is a major sink for anthropogenic CO2 emissions and hence it plays an essential role in modulating global carbon cycle and climate change. Previous studies based on observations (e.g., Landschützer et al. 2015) show pronounced decadal variations of carbon uptake in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in recent decades and this variability is largely driven by internal climate variability. However, due to limited ensemble size of simulations, the variability of this important <span class="hlt">ocean</span> sink is still poorly assessed by the state-of-the-art earth system models (ESMs). To assess the internal variability of carbon sink in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, we use a large ensemble of 100 member simulations based on the Max Planck Institute-ESM (MPI-ESM). The large ensemble of simulations is generated via perturbed initial conditions in the <span class="hlt">ocean</span> and atmosphere. Each ensemble member includes a historical simulation from 1850 to 2005 with an extension until 2100 under Representative Concentration Pathway (RCP) 4.5 future projections. Here we use model simulations from 1980-2015 to compare with available observation-based dataset. We found several ensemble members showing decadal decreasing trends in the carbon sink, which are similar to the trend shown in observations. This result suggests that MPI-ESM large ensemble simulations are able to reproduce decadal variation of carbon sink in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Moreover, the decreasing trends of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> carbon sink in MPI-ESM are mainly contributed by region between 50-60°S. To understand the internal variability of the air-sea carbon fluxes in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, we further investigate the variability of underlying processes, such as physical climate variability and <span class="hlt">ocean</span> biological processes. Our results indicate two main drivers for the decadal decreasing trend of carbon sink: i) Intensified winds enhance upwelling of old carbon-rich waters, this leads to increase of the <span class="hlt">ocean</span> surface pCO2; ii) Primary production is reduced in area</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018BGeo...15.2851P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018BGeo...15.2851P"><span>The seasonal cycle of pCO2 and CO2 fluxes in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>: diagnosing anomalies in CMIP5 Earth system models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Precious Mongwe, N.; Vichi, Marcello; Monteiro, Pedro M. S.</p> <p>2018-05-01</p> <p>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> forms an important component of the Earth system as a major sink of CO2 and heat. Recent studies based on the Coupled Model Intercomparison Project version 5 (CMIP5) Earth system models (ESMs) show that CMIP5 models disagree on the phasing of the seasonal cycle of the CO2 flux (FCO2) and compare poorly with available observation products for the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Because the seasonal cycle is the dominant mode of CO2 variability in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, its simulation is a rigorous test for models and their long-term projections. Here we examine the competing roles of temperature and dissolved inorganic carbon (DIC) as drivers of the seasonal cycle of pCO2 in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> to explain the mechanistic basis for the seasonal biases in CMIP5 models. We find that despite significant differences in the spatial characteristics of the mean annual fluxes, the intra-model homogeneity in the seasonal cycle of FCO2 is greater than observational products. FCO2 biases in CMIP5 models can be grouped into two main categories, i.e., group-SST and group-DIC. Group-SST models show an exaggeration of the seasonal rates of change of sea surface temperature (SST) in autumn and spring during the cooling and warming peaks. These higher-than-observed rates of change of SST tip the control of the seasonal cycle of pCO2 and FCO2 towards SST and result in a divergence between the observed and modeled seasonal cycles, particularly in the Sub-<span class="hlt">Antarctic</span> Zone. While almost all analyzed models (9 out of 10) show these SST-driven biases, 3 out of 10 (namely NorESM1-ME, HadGEM-ES and MPI-ESM, collectively the group-DIC models) compensate for the solubility bias because of their overly exaggerated primary production, such that biologically driven DIC changes mainly regulate the seasonal cycle of FCO2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170003456','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170003456"><span>Observation Impact over the <span class="hlt">Antarctic</span> During the Concordiasi Field Campaign</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Boullot, Nathalie; Rabier, Florence; Langland, Rolf; Gelaro, Ron; Cardinali, Carla; Guidard, Vincent; Bauer, Peter; Doerenbecher, Alexis</p> <p>2014-01-01</p> <p>The impact of observations on analysis uncertainty and forecast performance was investigated for Austral Spring 2010 over the <span class="hlt">Southern</span> polar area for four different systems (NRL, GMAO, ECMWF and Meteo-France), at the time of the Concordiasi field experiment. The largest multi model variance in 500 hPa height analyses is found in the <span class="hlt">southern</span> sub-<span class="hlt">Antarctic</span> <span class="hlt">oceanic</span> region, where there are strong atmospheric dynamics, rapid forecast error growth, and fewer upper air wind observation data to constrain the analyses. In terms of data impact the most important observation components are shown to be AMSU, IASI, AIRS, GPS-RO, radiosonde, surface and atmospheric motion vector observations. For sounding data, radiosondes and dropsondes, one can note a large impact of temperature at low levels and a large impact of wind at high levels. Observing system experiments using the Concordiasi dropsondes show a large impact of the observations over the <span class="hlt">Antarctic</span> plateau extending to lower latitudes with the forecast range, with a large impact around 50 to 70deg South. These experiments indicate there is a potential benefit of better using radiance data over land and sea-ice and innovative atmospheric motion vectors obtained from a combination of various satellites to fill the current data gaps and improve NWP in this region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29796342','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29796342"><span>Effect of elevated temperature on membrane lipid saturation in <span class="hlt">Antarctic</span> notothenioid fish.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Malekar, Vanita C; Morton, James D; Hider, Richard N; Cruickshank, Robert H; Hodge, Simon; Metcalf, Victoria J</p> <p>2018-01-01</p> <p>Homeoviscous adaptation (HVA) is a key cellular response by which fish protect their membranes against thermal stress. We investigated evolutionary HVA (long time scale) in <span class="hlt">Antarctic</span> and non-<span class="hlt">Antarctic</span> fish. Membrane lipid composition was determined for four Perciformes fish: two closely related <span class="hlt">Antarctic</span> notothenioid species ( Trematomus bernacchii and Pagothenia borchgrevinki ); a diversified related notothenioid <span class="hlt">Antarctic</span> icefish ( Chionodraco hamatus ); and a New Zealand species ( Notolabrus celidotus ). The membrane lipid compositions were consistent across the three <span class="hlt">Antarctic</span> species and these were significantly different from that of the New Zealand species. Furthermore, acclimatory HVA (short time periods with seasonal changes) was investigated to determine whether stenothermal <span class="hlt">Antarctic</span> fish, which evolved in the cold, stable environment of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, have lost the acclimatory capacity to modulate their membrane saturation states, making them vulnerable to anthropogenic global warming. We compared liver membrane lipid composition in two closely related <span class="hlt">Antarctic</span> fish species acclimated at 0 °C (control temperature), 4 °C for a period of 14 days in T. bernacchii and 28 days for P. borchgrevinki, and 6 °C for 7 days in both species. Thermal acclimation at 4 °C did not result in changed membrane saturation states in either <span class="hlt">Antarctic</span> species. Despite this, membrane functions were not compromised, as indicated by declining serum osmolality, implying positive compensation by enhanced hypo-osmoregulation. Increasing the temperature to 6 °C did not change the membrane lipids of P. borchgrevinki. However, in T. bernacchii, thermal acclimation at 6 °C resulted in an increase of membrane saturated fatty acids and a decline in unsaturated fatty acids. This is the first study to show a homeoviscous response to higher temperatures in an <span class="hlt">Antarctic</span> fish, although for only one of the two species examined.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSHE44B1511L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSHE44B1511L"><span>Contribution of Increasing Glacial Freshwater Fluxes to Observed Trends in <span class="hlt">Antarctic</span> Sea Ice</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Le Sommer, J.; Merino, N.; Durand, G.; Jourdain, N.; Goosse, H.; Mathiot, P.; Gurvan, M.</p> <p>2016-02-01</p> <p><span class="hlt">Southern</span> <span class="hlt">Ocean</span> sea-ice extent has experienced an overall positive trend over recent decades. While the amplitude of this trend is open to debate, the geographical pattern of regional changes has been clearly identified by observations. Mechanisms driving changes in the <span class="hlt">Antarctic</span> Sea Ice Extent (SIE) are not fully understood and climate models fail to simulate these trends. Changes in different atmospheric features such as SAM or ENSO seem to explain the observed trend of Antartic sea ice, but only partly, since they can not account for the actual amplitude of the observed signal. The increasing injection of freshwater due to the accelerating ice discharge from Antarctica Ice Sheet (AIS) during the last two decades has been proposed as another candidate to contribute to SIE trend. However, the quantity and the distribution of the extra freshwater injection were not properly constrained. Recent glaciological estimations may improve the way the glacial freshwater is injected in the model. Here, we study the role of the glacial freshwater into the observed SIE trend, using the state-of-the-art <span class="hlt">Antarctic</span> mass loss estimations. <span class="hlt">Ocean</span>/sea-ice model simulations have been carried out with two different <span class="hlt">Antarctic</span> freshwater scenarios corresponding to 20-years of <span class="hlt">Antarctic</span> Ice Sheet evolution. The combination of an improved iceberg model with the most recent glaciological estimations has been applied to account for the most realistic possible <span class="hlt">Antarctic</span> freshwater evolution scenarios. Results suggest that Antarctica has contributed to almost a 30% of the observed trend in regions of the South Pacific and South East Indian sectors, but has little impact in the South Atlantic sector. We conclude that the observed SIE trend over the last decades is due to a combination of both an atmospheric forcing and the extra freshwater injection. Our results advocates that the evolution of glacial freshwater needs to be correctly represented in climate models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25143114','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25143114"><span>A microbial ecosystem beneath the West <span class="hlt">Antarctic</span> ice sheet.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Christner, Brent C; Priscu, John C; Achberger, Amanda M; Barbante, Carlo; Carter, Sasha P; Christianson, Knut; Michaud, Alexander B; Mikucki, Jill A; Mitchell, Andrew C; Skidmore, Mark L; Vick-Majors, Trista J</p> <p>2014-08-21</p> <p>Liquid water has been known to occur beneath the <span class="hlt">Antarctic</span> ice sheet for more than 40 years, but only recently have these subglacial aqueous environments been recognized as microbial ecosystems that may influence biogeochemical transformations on a global scale. Here we present the first geomicrobiological description of water and surficial sediments obtained from direct sampling of a subglacial <span class="hlt">Antarctic</span> lake. Subglacial Lake Whillans (SLW) lies beneath approximately 800 m of ice on the lower portion of the Whillans Ice Stream (WIS) in West Antarctica and is part of an extensive and evolving subglacial drainage network. The water column of SLW contained metabolically active microorganisms and was derived primarily from glacial ice melt with solute sources from lithogenic weathering and a minor seawater component. Heterotrophic and autotrophic production data together with small subunit ribosomal RNA gene sequencing and biogeochemical data indicate that SLW is a chemosynthetically driven ecosystem inhabited by a diverse assemblage of bacteria and archaea. Our results confirm that aquatic environments beneath the <span class="hlt">Antarctic</span> ice sheet support viable microbial ecosystems, corroborating previous reports suggesting that they contain globally relevant pools of carbon and microbes that can mobilize elements from the lithosphere and influence <span class="hlt">Southern</span> <span class="hlt">Ocean</span> geochemical and biological systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011CliPa...7.1123R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011CliPa...7.1123R"><span>Interhemispheric gradient of atmospheric radiocarbon reveals natural variability of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> winds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rodgers, K. B.; Mikaloff-Fletcher, S. E.; Bianchi, D.; Beaulieu, C.; Galbraith, E. D.; Gnanadesikan, A.; Hogg, A. G.; Iudicone, D.; Lintner, B. R.; Naegler, T.; Reimer, P. J.; Sarmiento, J. L.; Slater, R. D.</p> <p>2011-10-01</p> <p>Tree ring Δ14C data (Reimer et al., 2004; McCormac et al., 2004) indicate that atmospheric Δ14C varied on multi-decadal to centennial timescales, in both hemispheres, over the period between AD 950 and 1830. The Northern and <span class="hlt">Southern</span> Hemispheric Δ14C records display similar variability, but from the data alone is it not clear whether these variations are driven by the production of 14C in the stratosphere (Stuiver and Quay, 1980) or by perturbations to exchanges between carbon reservoirs (Siegenthaler et al., 1980). As the sea-air flux of 14CO2 has a clear maximum in the open <span class="hlt">ocean</span> regions of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, relatively modest perturbations to the winds over this region drive significant perturbations to the interhemispheric gradient. In this study, model simulations are used to show that <span class="hlt">Southern</span> <span class="hlt">Ocean</span> winds are likely a main driver of the observed variability in the interhemispheric gradient over AD 950-1830, and further, that this variability may be larger than the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> wind trends that have been reported for recent decades (notably 1980-2004). This interpretation also implies that there may have been a significant weakening of the winds over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> within a few decades of AD 1375, associated with the transition between the Medieval Climate Anomaly and the Little Ice Age. The driving forces that could have produced such a shift in the winds at the Medieval Climate Anomaly to Little Ice Age transition remain unknown. Our process-focused suite of perturbation experiments with models raises the possibility that the current generation of coupled climate and earth system models may underestimate the natural background multi-decadal- to centennial-timescale variations in the winds over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSHE44D1548G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSHE44D1548G"><span>Inferring Source Regions and Supply Mechanisms of Iron in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> from Satellite Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Graham, R. M.</p> <p>2016-02-01</p> <p>In many biogeochemical models a large shelf sediment iron flux is prescribed through the seafloor over all areas of bathymetry shallower than 1000 m. Here we infer the likely location of shelf sediment iron sources by identifying where mean annual satellite chlorophyll concentrations are enhanced over shallow bathymetry ( < 1000 m). We show that mean annual chlorophyll concentrations are not visibly enhanced over areas of shallow bathymetry located more than 500 km from a coastline. Chlorophyll concentrations > 2 mg m-3are only found within 50 km of a continental or island coastline. These results suggest that large sedimentary iron fluxes only exist on continental or island shelves. Large sedimentary iron fluxes are unlikely to be found on isolated seamounts and submerged plateaus. We further compare satellite chlorophyll concentrations to the position of <span class="hlt">ocean</span> fronts to assess the relative role of horizontal advection and upwelling for supplying iron to the <span class="hlt">ocean</span> surface. Sharp gradients in chlorophyll concentrations are observed across western boundary currents. Large chlorophyll blooms develop where western boundary currents detach from the continental shelves and turn eastwards into the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. Chlorophyll concentrations are enhanced along contours of sea surface height extending off continental and island shelves. These observations support the hypothesis that bioavailable iron from continental shelves is entrained into western boundary currents and advected into the Sub-<span class="hlt">Antarctic</span> Zone along the Dynamical Subtropical Front. Likewise, iron from island shelves is entrained into nearby fronts and advected downstream. Mean annual chlorophyll concentrations are very low in open <span class="hlt">ocean</span> regions with large modelled upwelling velocities, where fronts cross over topographic ridges. These results suggests that open <span class="hlt">ocean</span> upwelling is unlikely to deliver iron to the surface from deep sources such as hydrothermal vents.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017DSRII.139...31V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017DSRII.139...31V"><span>Characteristics of the modelled meteoric freshwater budget of the western <span class="hlt">Antarctic</span> Peninsula</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>van Wessem, J. M.; Meredith, M. P.; Reijmer, C. H.; van den Broeke, M. R.; Cook, A. J.</p> <p>2017-05-01</p> <p>Rapid climatic changes in the western <span class="hlt">Antarctic</span> Peninsula (WAP) have led to considerable changes in the meteoric freshwater input into the surrounding <span class="hlt">ocean</span>, with implications for <span class="hlt">ocean</span> circulation, the marine ecosystem and sea-level rise. In this study, we use the high-resolution Regional Atmospheric Climate Model RACMO2.3, coupled to a firn model, to assess the various contributions to the meteoric freshwater budget of the WAP for 1979-2014: precipitation (snowfall and rainfall), meltwater runoff to the <span class="hlt">ocean</span>, and glacial discharge. Snowfall is the largest component in the atmospheric contribution to the freshwater budget, and exhibits large spatial and temporal variability. The highest snowfall rates are orographically forced and occur over the coastal regions of the WAP (> 2000 mm water equivalent (w.e.) y-1) and extend well onto the <span class="hlt">ocean</span> up to the continental shelf break; a minimum (∼ 500 mm w . e .y-1) is reached over the open <span class="hlt">ocean</span>. Rainfall is an order of magnitude smaller, and strongly depends on latitude and season, being large in summer, when sea ice extent is at its minimum. For <span class="hlt">Antarctic</span> standards, WAP surface meltwater production is relatively large (> 50 mm w . e .y-1) , but a large fraction refreezes in the snowpack, limiting runoff. Only at a few more northerly locations is the meltwater predicted to run off into the <span class="hlt">ocean</span>. In summer, we find a strong relationship of the freshwater fluxes with the <span class="hlt">Southern</span> Annular Mode (SAM) index. When SAM is positive and occurs simultaneously with a La Niña event there are anomalously strong westerly winds and enhanced snowfall rates over the WAP mountains, Marguerite Bay and the Bellingshausen Sea. When SAM coincides with an El Niño event, winds are more northerly, reducing snowfall and increasing rainfall over the <span class="hlt">ocean</span>, and enhancing orographic snowfall over the WAP mountains. Assuming balance between snow accumulation (mass gain) and glacial discharge (mass loss), the largest glacial discharge is found</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997amc..book.....K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997amc..book.....K"><span><span class="hlt">Antarctic</span> Meteorology and Climatology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>King, J. C.; Turner, J.</p> <p>1997-07-01</p> <p>This book is a comprehensive survey of the climatology and meteorology of Antarctica. The first section of the book reviews the methods by which we can observe the <span class="hlt">Antarctic</span> atmosphere and presents a synthesis of climatological measurements. In the second section, the authors consider the processes that maintain the observed climate, from large-scale atmospheric circulation to small-scale processes. The final section reviews our current knowledge of the variability of <span class="hlt">Antarctic</span> climate and the possible effects of "greenhouse" warming. The authors stress links among the <span class="hlt">Antarctic</span> atmosphere, other elements of the <span class="hlt">Antarctic</span> climate system (<span class="hlt">oceans</span>, sea ice and ice sheets), and the global climate system. This volume will be of greatest interest to meteorologists and climatologists with a specialized interest in Antarctica, but it will also appeal to researchers in <span class="hlt">Antarctic</span> glaciology, oceanography and biology. Graduates and undergraduates studying physical geography, and the earth, atmospheric and environmental sciences will find much useful background material in the book.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28100418','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28100418"><span>Persistent organic pollutants in the Atlantic and <span class="hlt">southern</span> <span class="hlt">oceans</span> and <span class="hlt">oceanic</span> atmosphere.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Luek, Jenna L; Dickhut, Rebecca M; Cochran, Michele A; Falconer, Renee L; Kylin, Henrik</p> <p>2017-04-01</p> <p>Persistent organic pollutants (POPs) continue to cycle through the atmosphere and hydrosphere despite banned or severely restricted usages. Global scale analyses of POPs are challenging, but knowledge of the current distribution of these compounds is needed to understand the movement and long-term consequences of their global use. In the current study, air and seawater samples were collected Oct. 2007-Jan. 2008 aboard the Icebreaker Oden en route from Göteborg, Sweden to McMurdo Station, Antarctica. Both air and surface seawater samples consistently contained α-hexachlorocyclohexane (α-HCH), γ-HCH, hexachlorobenzene (HCB), α-Endosulfan, and polychlorinated biphenyls (PCBs). Sample concentrations for most POPs in air were higher in the northern hemisphere with the exception of HCB, which had high gas phase concentrations in the northern and <span class="hlt">southern</span> latitudes and low concentrations near the equator. South Atlantic and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> seawater had a high ratio of α-HCH to γ-HCH, indicating persisting levels from technical grade sources. The Atlantic and <span class="hlt">Southern</span> <span class="hlt">Ocean</span> continue to be net sinks for atmospheric α-, γ-HCH, and Endosulfan despite declining usage. Copyright © 2017 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ClDy...44.2267Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ClDy...44.2267Z"><span>Impact of the initialisation on the predictability of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> sea ice at interannual to multi-decadal timescales</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zunz, Violette; Goosse, Hugues; Dubinkina, Svetlana</p> <p>2015-04-01</p> <p>In this study, we assess systematically the impact of different initialisation procedures on the predictability of the sea ice in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. These initialisation strategies are based on three data assimilation methods: the nudging, the particle filter with sequential importance resampling and the nudging proposal particle filter. An Earth system model of intermediate complexity is used to perform hindcast simulations in a perfect model approach. The predictability of the <span class="hlt">Antarctic</span> sea ice at interannual to multi-decadal timescales is estimated through two aspects: the spread of the hindcast ensemble, indicating the uncertainty of the ensemble, and the correlation between the ensemble mean and the pseudo-observations, used to assess the accuracy of the prediction. Our results show that at decadal timescales more sophisticated data assimilation methods as well as denser pseudo-observations used to initialise the hindcasts decrease the spread of the ensemble. However, our experiments did not clearly demonstrate that one of the initialisation methods systematically provides with a more accurate prediction of the sea ice in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> than the others. Overall, the predictability at interannual timescales is limited to 3 years ahead at most. At multi-decadal timescales, the trends in sea ice extent computed over the time period just after the initialisation are clearly better correlated between the hindcasts and the pseudo-observations if the initialisation takes into account the pseudo-observations. The correlation reaches values larger than 0.5 in winter. This high correlation has likely its origin in the slow evolution of the <span class="hlt">ocean</span> ensured by its strong thermal inertia, showing the importance of the quality of the initialisation below the sea ice.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JMS...161...26C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JMS...161...26C"><span>Developing priority variables ("ecosystem Essential <span class="hlt">Ocean</span> Variables" - eEOVs) for observing dynamics and change in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ecosystems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Constable, Andrew J.; Costa, Daniel P.; Schofield, Oscar; Newman, Louise; Urban, Edward R.; Fulton, Elizabeth A.; Melbourne-Thomas, Jessica; Ballerini, Tosca; Boyd, Philip W.; Brandt, Angelika; de la Mare, Willaim K.; Edwards, Martin; Eléaume, Marc; Emmerson, Louise; Fennel, Katja; Fielding, Sophie; Griffiths, Huw; Gutt, Julian; Hindell, Mark A.; Hofmann, Eileen E.; Jennings, Simon; La, Hyoung Sul; McCurdy, Andrea; Mitchell, B. Greg; Moltmann, Tim; Muelbert, Monica; Murphy, Eugene; Press, Anthony J.; Raymond, Ben; Reid, Keith; Reiss, Christian; Rice, Jake; Salter, Ian; Smith, David C.; Song, Sun; Southwell, Colin; Swadling, Kerrie M.; Van de Putte, Anton; Willis, Zdenka</p> <p>2016-09-01</p> <p>Reliable statements about variability and change in marine ecosystems and their underlying causes are needed to report on their status and to guide management. Here we use the Framework on <span class="hlt">Ocean</span> Observing (FOO) to begin developing ecosystem Essential <span class="hlt">Ocean</span> Variables (eEOVs) for the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Observing System (SOOS). An eEOV is a defined biological or ecological quantity, which is derived from field observations, and which contributes significantly to assessments of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ecosystems. Here, assessments are concerned with estimating status and trends in ecosystem properties, attribution of trends to causes, and predicting future trajectories. eEOVs should be feasible to collect at appropriate spatial and temporal scales and are useful to the extent that they contribute to direct estimation of trends and/or attribution, and/or development of ecological (statistical or simulation) models to support assessments. In this paper we outline the rationale, including establishing a set of criteria, for selecting eEOVs for the SOOS and develop a list of candidate eEOVs for further evaluation. Other than habitat variables, nine types of eEOVs for <span class="hlt">Southern</span> <span class="hlt">Ocean</span> taxa are identified within three classes: state (magnitude, genetic/species, size spectrum), predator-prey (diet, foraging range), and autecology (phenology, reproductive rate, individual growth rate, detritus). Most candidates for the suite of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> taxa relate to state or diet. Candidate autecological eEOVs have not been developed other than for marine mammals and birds. We consider some of the spatial and temporal issues that will influence the adoption and use of eEOVs in an observing system in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, noting that existing operations and platforms potentially provide coverage of the four main sectors of the region - the East and West Pacific, Atlantic and Indian. Lastly, we discuss the importance of simulation modelling in helping with the design of the observing system in the long</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993EOSTr..74...59S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993EOSTr..74...59S"><span>Including eddies in global <span class="hlt">ocean</span> models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Semtner, Albert J.; Chervin, Robert M.</p> <p></p> <p>The <span class="hlt">ocean</span> is a turbulent fluid that is driven by winds and by surface exchanges of heat and moisture. It is as important as the atmosphere in governing climate through heat distribution, but so little is known about the <span class="hlt">ocean</span> that it remains a “final frontier” on the face of the Earth. Many <span class="hlt">ocean</span> currents are truly global in extent, such as the <span class="hlt">Antarctic</span> Circumpolar Current and the “conveyor belt” that connects the North Atlantic and North Pacific <span class="hlt">oceans</span> by flows around the <span class="hlt">southern</span> tips of Africa and South America. It has long been a dream of some oceanographers to supplement the very limited observational knowledge by reconstructing the currents of the world <span class="hlt">ocean</span> from the first principles of physics on a computer. However, until very recently, the prospect of doing this was thwarted by the fact that fluctuating currents known as “mesoscale eddies” could not be explicitly included in the calculation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.C34B..04F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.C34B..04F"><span>Sequence stratigraphy of the ANDRILL <span class="hlt">Southern</span> McMurdo Sound (SMS) project drillcore, Antarctica: an expanded, near-field record of <span class="hlt">Antarctic</span> Early to Middle Miocene climate and relative sea-level change</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fielding, C. R.; Browne, G. H.; Field, B.; Florindo, F.; Harwood, D. M.; Krissek, L. A.; Levy, R. H.; Panter, K.; Passchier, S.; Pekar, S. F.; SMS Science Team</p> <p>2008-12-01</p> <p>Present understanding of <span class="hlt">Antarctic</span> climate change during the Early to Middle Miocene, including definition of major cycles of glacial expansion and contraction, relies in large part on stable isotope proxy records from <span class="hlt">Ocean</span> Drilling Program cores. Here, we present a sequence stratigraphic analysis of the <span class="hlt">Southern</span> McMurdo Sound drillcore (AND-2A), which was acquired during the Austral Spring of 2007. This core offers a hitherto unavailable ice-proximal stratigraphic archive of the Early to Middle Miocene from a high-accommodation <span class="hlt">Antarctic</span> continental margin setting, and provides clear evidence of repeated fluctuations in climate, ice expansion/contraction and attendant sea-level change over the period 20-14 Ma, with a more fragmentary record of the post-14 Ma period. A succession of seventy sequences is recognized, each bounded by a significant facies dislocation (sequence boundary), composed internally of deposits of glacimarine to open shallow marine environments, and each typically dominated by the transgressive systems tract. From changes in facies abundances and sequence character, a series of long-term (m.y.) changes in climate and relative sea-level is identified. The lithostratigraphy can be correlated confidently to glacial events Mi1b and Mi2, to the Miocene Climatic Optimum, and to the global eustatic sea-level curve. SMS provides a detailed, direct, ice-proximal reference point from which to evaluate stable isotope proxy records for Neogene <span class="hlt">Antarctic</span> paleoclimate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..1111226R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..1111226R"><span>Atmospheric radiocarbon as a <span class="hlt">Southern</span> <span class="hlt">Ocean</span> wind proxy over the last 1000 years</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rodgers, K. B.; Mikaloff Fletcher, S.; Galbraith, E.; Sarmiento, J. L.; Gnanadesikan, A.; Slater, R. D.; Naegler, T.</p> <p>2009-04-01</p> <p>Measurements of radiocarbon in tree rings over the last 1000 years indicate that there was a pre-industrial latitudinal gradient of atmospheric radiocarbon of 3.9-4.5 per mail and that this gradient had temporal variability of order 6 per mil. Here we test the idea that the mean gradient as well as variability in he gradient is dominated by the strength of the winds over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. This is done using an <span class="hlt">ocean</span> model and an atmospheric transport model. The <span class="hlt">ocean</span> model is used to derive fluxes of 12CO2 and 14CO2 at the sea surface, and these fluxes are used as a lower boundary condition for the transport model. For the mean state, strong winds in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> drive significant upwelling of radiocarbon-depleted Circumpolar Deep Water (CDW), leading to a net flux of 14CO2 relative to 12CO2 into the <span class="hlt">ocean</span>. This serves to maintain a hemispheric gradient in pre-anthropogenic atmospheric delta-c14. For perturbations, increased/decreased <span class="hlt">Southern</span> <span class="hlt">Ocean</span> winds drive increased/decreased uptake of 14CO2 relative to 12CO2, thus increasing/decreasing the hemispheric gradient in atmospheric delta-c14. The tree ring data is interpreted to reveal a decrease in the strength of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> winds at the transition between the Little Ice Age and the Medieval Warm Period.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.T13B0516F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.T13B0516F"><span>Satellite gravity gradient views help reveal the <span class="hlt">Antarctic</span> lithosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ferraccioli, F.; Ebbing, J.; Pappa, F.; Kern, M.; Forsberg, R.</p> <p>2017-12-01</p> <p>Here we present and analyse satellite gravity gradient signatures derived from GOCE and superimpose these on tectonic and bedrock topography elements, as well as seismically-derived estimates of crustal thickness for the <span class="hlt">Antarctic</span> continent. The GIU satellite gravity component images the contrast between the thinner crust and lithosphere underlying the West <span class="hlt">Antarctic</span> Rift System and the Weddell Sea Rift System and the thicker lithosphere of East Antarctica. The new images also suggest that more distributed wide-mode lithospheric and crustal extension affects both the Ross Sea Embayment and the less well known Ross Ice Shelf segment of the rift system. However, this pattern is less clear towards the Bellingshousen Embayment, indicating that the rift system narrows towards the <span class="hlt">southern</span> edge of the <span class="hlt">Antarctic</span> Peninsula. In East Antarctica, the satellite gravity data provides new views into the Archean to Mesoproterozoic Terre Adelie Craton, and clearly shows the contrast wrt to the crust and lithosphere underlying both the Wilkes Subglacial Basin to the east and the Sabrina Subglacial Basin to the west. This finding augments recent interpretations of aeromagnetic and airborne gravity data over the region, suggesting that the Mawson Continent is a composite lithospheric-scale entity, which was affected by several Paleoproterozoic and Mesoproterozoic orogenic events. Thick crust is imaged beneath the Transantarctic Mountains, the Terre Adelie Craton, the Gamburtsev Subglacial Mountains and also Eastern Dronning Maud Land, in particular beneath the recently proposed region of the Tonian <span class="hlt">Oceanic</span> Arc Superterrane. The GIA and GIU components help delineate the edges of several of these lithospheric provinces. One of the most prominent lithospheric-scale features discovered in East Antarctica from satellite gravity gradient imaging is the Trans East <span class="hlt">Antarctic</span> Shear Zone that separates the Gamburtsev Province from the Eastern Dronning Maud Land Province and appears to form the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012DSRI...63...91R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012DSRI...63...91R"><span>Advective pathways near the tip of the <span class="hlt">Antarctic</span> Peninsula: Trends, variability and ecosystem implications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Renner, Angelika H. H.; Thorpe, Sally E.; Heywood, Karen J.; Murphy, Eugene J.; Watkins, Jon L.; Meredith, Michael P.</p> <p>2012-05-01</p> <p>Pathways and rates of <span class="hlt">ocean</span> flow near the <span class="hlt">Antarctic</span> Peninsula are strongly affected by frontal features, forcings from the atmosphere and the cryosphere. In the surface mixed layer, the currents advect material from the northwestern Weddell Sea on the eastern side of the Peninsula around the tip of the Peninsula to its western side and into the Scotia Sea, connecting populations of <span class="hlt">Antarctic</span> krill (Euphausia superba) and supporting the ecosystem of the region. Modelling of subsurface drifters using a particle tracking algorithm forced by the velocity fields of a coupled sea ice-<span class="hlt">ocean</span> model (ORCA025-LIM2) allows analysis of the seasonal and interannual variability of drifter pathways over 43 years. The results show robust and persistent connections from the Weddell Sea both to the west into the Bellingshausen Sea and across the Scotia Sea towards South Georgia, reproducing well the observations. The fate of the drifters is sensitive to their deployment location, in addition to other factors. From the shelf of the eastern <span class="hlt">Antarctic</span> Peninsula, the majority enter the Bransfield Strait and subsequently the Bellingshausen Sea. When originating further offshore over the deeper Weddell Sea, drifters are more likely to cross the South Scotia Ridge and reach South Georgia. However, the wind field east and southeast of Elephant Island, close to the tip of the Peninsula, is crucial for the drifter trajectories and is highly influenced by the <span class="hlt">Southern</span> Annular Mode (SAM). Increased advection and short travel times to South Georgia, and reduced advection to the western <span class="hlt">Antarctic</span> Peninsula can be linked to strong westerlies, a signature of the positive phase of the SAM. The converse is true for the negative phase. Strong westerlies and shifts of <span class="hlt">ocean</span> fronts near the tip of the Peninsula that are potentially associated with both the SAM and the El Niño-<span class="hlt">Southern</span> Oscillation restrict the connection from the Weddell Sea to the west, and drifters then predominantly follow the open</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA257132','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA257132"><span>Investigation of <span class="hlt">Antarctic</span> Sea Ice Concentration by Means of Selected Algorithms</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1992-05-08</p> <p>Changes in areal extent and concentration of sea ice around Antarctica may serve as sensitive indicators of global warming . A comparison study was...occurred from July, 1987 through June, 1990. <span class="hlt">Antarctic</span> <span class="hlt">Ocean</span>, <span class="hlt">Antarctic</span> regions, Global warming , Sea ice-<span class="hlt">Antarctic</span> regions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004DSRII..51.1369K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004DSRII..51.1369K"><span>Salp distribution and size composition in the Atlantic sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kawaguchi, S.; Siegel, V.; Litvinov, F.; Loeb, V.; Watkins, J.</p> <p>2004-06-01</p> <p>Salp abundance and length frequency were measured during the large-scale CCAMLR 2000 Survey conducted in the Atlantic Sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> in the 1999/2000 season. Results from regional surveys around Elephant Island in 1994/95 and 1996/97 seasons also were examined. During the CCAMLR 2000 Survey, salp abundance was higher in the <span class="hlt">Antarctic</span> Peninsula and South Sandwich Island areas than in the central Scotia Sea. The probable reason for this pattern is a negative relationship with phytoplankton abundance; the central Scotia Sea having greater phytoplankton concentrations than required for optimal salp filter-feeding performance. Cluster analysis of salp size composition resulted in three cluster groups for each of the three surveys. Clusters comprising large salps occurred in warmer waters in all three surveys. The size composition of the salp populations suggests that the timing of intense asexual reproductive budding was earlier in warmer waters. As surface water temperatures generally decrease from north to south, and increase from spring to summer, the general spatio-temporal pattern of asexual reproduction by budding is likely to proceed from north to south as the summer season progresses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GeoRL..45.4198S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GeoRL..45.4198S"><span>Convection Enhances Mixing in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sohail, Taimoor; Gayen, Bishakhdatta; Hogg, Andrew McC.</p> <p>2018-05-01</p> <p>Mixing efficiency is a measure of the energy lost to mixing compared to that lost to viscous dissipation. In a turbulent stratified fluid the mixing efficiency is often assumed constant at η = 0.2, whereas with convection it takes values closer to 1. The value of mixing efficiency when both stratified shear flow and buoyancy-driven convection are active remains uncertain. We use a series of numerical simulations to determine the mixing efficiency in an idealized <span class="hlt">Southern</span> <span class="hlt">Ocean</span> model. The model is energetically closed and fully resolves convection and turbulence such that mixing efficiency can be diagnosed. Mixing efficiency decreases with increasing wind stress but is enhanced by turbulent convection and by large thermal gradients in regions with a strongly stratified thermocline. Using scaling theory and the model results, we predict an overall mixing efficiency for the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> that is significantly greater than 0.2 while emphasizing that mixing efficiency is not constant.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25818178','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25818178"><span>Pyrosequencing and de novo assembly of <span class="hlt">Antarctic</span> krill (Euphausia superba) transcriptome to study the adaptability of krill to climate-induced environmental changes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Meyer, B; Martini, P; Biscontin, A; De Pittà, C; Romualdi, C; Teschke, M; Frickenhaus, S; Harms, L; Freier, U; Jarman, S; Kawaguchi, S</p> <p>2015-11-01</p> <p>The <span class="hlt">Antarctic</span> krill, Euphausia superba, has a key position in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> food web by serving as direct link between primary producers and apex predators. The south-west Atlantic sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, where the majority of the krill population is located, is experiencing one of the most profound environmental changes worldwide. Up to now, we have only cursory information about krill's genomic plasticity to cope with the ongoing environmental changes induced by anthropogenic CO2 emission. The genome of krill is not yet available due to its large size (about 48 Gbp). Here, we present two cDNA normalized libraries from whole krill and krill heads sampled in different seasons that were combined with two data sets of krill transcriptome projects, already published, to produce the first knowledgebase krill 'master' transcriptome. The new library produced 25% more E. superba transcripts and now includes nearly all the enzymes involved in the primary oxidative metabolism (Glycolysis, Krebs cycle and oxidative phosphorylation) as well as all genes involved in glycogenesis, glycogen breakdown, gluconeogenesis, fatty acid synthesis and fatty acids β-oxidation. With these features, the 'master' transcriptome provides the most complete picture of metabolic pathways in <span class="hlt">Antarctic</span> krill and will provide a major resource for future physiological and molecular studies. This will be particularly valuable for characterizing the molecular networks that respond to stressors caused by the anthropogenic CO2 emissions and krill's capacity to cope with the ongoing environmental changes in the Atlantic sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. © 2015 The Authors. Molecular Ecology Resources published by John Wiley & Sons Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4672718','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4672718"><span>Pyrosequencing and de novo assembly of <span class="hlt">Antarctic</span> krill (Euphausia superba) transcriptome to study the adaptability of krill to climate-induced environmental changes</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Meyer, B; Martini, P; Biscontin, A; De Pittà, C; Romualdi, C; Teschke, M; Frickenhaus, S; Harms, L; Freier, U; Jarman, S; Kawaguchi, S</p> <p>2015-01-01</p> <p>The <span class="hlt">Antarctic</span> krill, Euphausia superba, has a key position in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> food web by serving as direct link between primary producers and apex predators. The south-west Atlantic sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, where the majority of the krill population is located, is experiencing one of the most profound environmental changes worldwide. Up to now, we have only cursory information about krill’s genomic plasticity to cope with the ongoing environmental changes induced by anthropogenic CO2 emission. The genome of krill is not yet available due to its large size (about 48 Gbp). Here, we present two cDNA normalized libraries from whole krill and krill heads sampled in different seasons that were combined with two data sets of krill transcriptome projects, already published, to produce the first knowledgebase krill ‘master’ transcriptome. The new library produced 25% more E. superba transcripts and now includes nearly all the enzymes involved in the primary oxidative metabolism (Glycolysis, Krebs cycle and oxidative phosphorylation) as well as all genes involved in glycogenesis, glycogen breakdown, gluconeogenesis, fatty acid synthesis and fatty acids β-oxidation. With these features, the ‘master’ transcriptome provides the most complete picture of metabolic pathways in <span class="hlt">Antarctic</span> krill and will provide a major resource for future physiological and molecular studies. This will be particularly valuable for characterizing the molecular networks that respond to stressors caused by the anthropogenic CO2 emissions and krill’s capacity to cope with the ongoing environmental changes in the Atlantic sector of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. PMID:25818178</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16346297','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16346297"><span>Bacterioplankton in <span class="hlt">antarctic</span> <span class="hlt">ocean</span> waters during late austral winter: abundance, frequency of dividing cells, and estimates of production.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hanson, R B; Shafer, D; Ryan, T; Pope, D H; Lowery, H K</p> <p>1983-05-01</p> <p>Bacterioplankton productivity in <span class="hlt">Antarctic</span> waters of the eastern South Pacific <span class="hlt">Ocean</span> and Drake Passage was estimated by direct counts and frequency of dividing cells (FDC). Total bacterioplankton assemblages were enumerated by epifluorescent microscopy. The experimentally determined relationship between in situ FDC and the potential instantaneous growth rate constant (mu) is best described by the regression equation ln mu = 0.081 FDC - 3.73. In the eastern South Pacific <span class="hlt">Ocean</span>, bacterioplankton abundance (2 x 10 to 3.5 x 10 cells per ml) and FDC (11%) were highest at the Polar Front (<span class="hlt">Antarctic</span> Convergence). North of the Subantarctic Front, abundance and FDC were between 1 x 10 to 2 x 10 cells per ml and 3 to 5%, respectively, and were vertically homogeneous to a depth of 600 m. In Drake Passage, abundance (10 x 10 cells per ml) and FDC (16%) were highest in waters south of the Polar Front and near the sea ice. Subantarctic waters in Drake Passage contained 4 x 10 cells per ml with 4 to 5% FDC. Instantaneous growth rate constants ranged between 0.029 and 0.088 h. Using estimates of potential mu and measured standing stocks, we estimated productivity to range from 0.62 mug of C per liter . day in the eastern South Pacific <span class="hlt">Ocean</span> to 17.1 mug of C per liter . day in the Drake Passage near the sea ice.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMGC32B..02P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMGC32B..02P"><span>Contrasting Trends in Arctic and <span class="hlt">Antarctic</span> Sea Ice Coverage Since the Late 1970s</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Parkinson, C. L.</p> <p>2016-12-01</p> <p>Satellite observations have allowed a near-continuous record of Arctic and <span class="hlt">Antarctic</span> sea ice coverage since late 1978. This record has revealed considerable interannual variability in both polar regions but also significant long-term trends, with the Arctic losing, the <span class="hlt">Antarctic</span> gaining, and the Earth as a whole losing sea ice coverage. Over the period 1979-2015, the trend in yearly average sea ice extents in the Arctic is -53,100 km2/yr (-4.3 %/decade) and in the <span class="hlt">Antarctic</span> is 23,800 km2/yr (2.1 %/decade). For all 12 months, trends are negative in the Arctic and positive in the <span class="hlt">Antarctic</span>, with the highest magnitude monthly trend being for September in the Arctic, at -85,300 km2/yr (-10.9 %/decade). The decreases in Arctic sea ice extents have been so dominant that not a single month since 1986 registered a new monthly record high, whereas 75 months registered new monthly record lows between 1987 and 2015 and several additional record lows were registered in 2016. The <span class="hlt">Antarctic</span> sea ice record highs and lows are also out of balance, in the opposite direction, although not in such dramatic fashion. Geographic details on the changing ice covers, down to the level of individual pixels, can be seen by examining changes in the length of the sea ice season. Results reveal (and quantify) shortening ice seasons throughout the bulk of the Arctic marginal ice zone, the main exception being within the Bering Sea, and lengthening sea ice seasons through much of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> but shortening seasons in the Bellingshausen Sea, <span class="hlt">southern</span> Amundsen Sea, and northwestern Weddell Sea. The decreasing Arctic sea ice coverage was widely anticipated and fits well with a large array of environmental changes in the Arctic, whereas the increasing <span class="hlt">Antarctic</span> sea ice coverage was not widely anticipated and explaining it remains an area of active research by many scientists exploring a variety of potential explanations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5316877','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5316877"><span>Climatically sensitive transfer of iron to maritime <span class="hlt">Antarctic</span> ecosystems by surface runoff</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hodson, Andy; Nowak, Aga; Sabacka, Marie; Jungblut, Anne; Navarro, Francisco; Pearce, David; Ávila-Jiménez, María Luisa; Convey, Peter; Vieira, Gonçalo</p> <p>2017-01-01</p> <p>Iron supplied by glacial weathering results in pronounced hotspots of biological production in an otherwise iron-limited <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Ecosystem. However, glacial iron inputs are thought to be dominated by icebergs. Here we show that surface runoff from three island groups of the maritime <span class="hlt">Antarctic</span> exports more filterable (<0.45 μm) iron (6–81 kg km−2 a−1) than icebergs (0.0–1.2 kg km−2 a−1). Glacier-fed streams also export more acid-soluble iron (27.0–18,500 kg km−2 a−1) associated with suspended sediment than icebergs (0–241 kg km−2 a−1). Significant fluxes of filterable and sediment-derived iron (1–10 Gg a−1 and 100–1,000 Gg a−1, respectively) are therefore likely to be delivered by runoff from the <span class="hlt">Antarctic</span> continent. Although estuarine removal processes will greatly reduce their availability to coastal ecosystems, our results clearly indicate that riverine iron fluxes need to be accounted for as the volume of <span class="hlt">Antarctic</span> melt increases in response to 21st century climate change. PMID:28198359</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://files.eric.ed.gov/fulltext/ED311985.pdf','ERIC'); return false;" href="http://files.eric.ed.gov/fulltext/ED311985.pdf"><span>The Need for a <span class="hlt">Southern</span> Branch Campus of <span class="hlt">Ocean</span> County College.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Ocean County Coll., Toms River, NJ. Office of Institutional Research.</p> <p></p> <p>In 1989, a study was conducted at <span class="hlt">Ocean</span> County College (OCC) to determine the feasibility of establishing a branch campus in <span class="hlt">southern</span> <span class="hlt">Ocean</span> County, New Jersey. Specific factors examined in the study included <span class="hlt">Ocean</span> County's demographic characteristics (e.g., land area and dispersion, population trends, public transportation, and economic trends);…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011CliPD...7..347R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011CliPD...7..347R"><span>Interhemispheric gradient of atmospheric radiocarbon reveals natural variability of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> winds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rodgers, K. B.; Fletcher, S. E. M.; Bianchi, D.; Beaulieu, C.; Galbraith, E. D.; Gnanadesikan, A.; Hogg, A. G.; Iudicone, D.; Lintner, B.; Naegler, T.; Reimer, P. J.; Sarmiento, J. L.; Slater, R. D.</p> <p>2011-01-01</p> <p>Tree ring Δ14C data (Reimer et al., 2004; McCormac et al., 2004) indicate that atmospheric Δ14C varied on multi-decadal to centennial timescales, in both hemispheres, over the pre-industrial period AD 950-1830. Although the Northern and <span class="hlt">Southern</span> Hemispheric Δ14C records display similar variability, it is difficult from these data alone to distinguish between variations driven by 14CO2 production in the upper atmosphere (Stuiver, 1980) and exchanges between carbon reservoirs (Siegenthaler, 1980). Here we consider rather the Interhemispheric Gradient in atmospheric Δ14C as revealing of the background pre-bomb air-sea Disequilbrium Flux between 14CO2 and CO2. As the global maximum of the Disequilibrium Flux is squarely centered in the open <span class="hlt">ocean</span> regions of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, relatively modest perturbations to the winds over this region drive significant perturbations to the Interhemispheric Gradient. The analysis presented here implies that changes to <span class="hlt">Southern</span> <span class="hlt">Ocean</span> windspeeds are likely a main driver of the observed variability in the Interhemispheric Gradient over 950-1830, and further, that this variability may be larger than the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> wind trends that have been reported for recent decades (notably 1980-2004). This interpretation also implies a significant weakening of the winds over the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> within a few decades of AD 1375, associated with the transition between the Medieval Climate Anomaly and the Little Ice Age. The driving forces that could have produced such a shift in the winds remain unkown.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920051541&hterms=Parkinsons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DParkinsons','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920051541&hterms=Parkinsons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DParkinsons"><span>Interannual variability of monthly <span class="hlt">Southern</span> <span class="hlt">Ocean</span> sea ice distributions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Parkinson, Claire L.</p> <p>1992-01-01</p> <p>The interannual variability of the <span class="hlt">Southern-Ocean</span> sea-ice distributions was mapped and analyzed using data from Nimbus-5 ESMR and Nimbus-7 SMMR, collected from 1973 to 1987. The set of 12 monthly maps obtained reveals many details on spatial variability that are unobtainable from time series of ice extents. These maps can be used as baseline maps for comparisons against future <span class="hlt">Southern</span> <span class="hlt">Ocean</span> sea ice distributions. The maps are supplemented by more detailed maps of the frequency of ice coverage, presented in this paper for one month within each of the four seasons, and by the breakdown of these results to the periods covered individually by each of the two passive-microwave imagers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.7907W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.7907W"><span>Impact of Icebergs on Net Primary Productivity in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Shuang-Ye; Hou, Shugui</p> <p>2017-04-01</p> <p>Productivity in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (SO) is iron-limited, and supply of iron dissolved from aeolian dust is believed to be the main source from outside the marine environment. However, recent studies show that icebergs could provide comparable amount of bioavailable iron to the SO as aeolian dust. In addition, small scale areal studies suggest increased concentrations of chlorophyll, krill, and seabirds surrounding icebergs. Based on previous research, this study aims to examine whether iceberg occurrence has a significant impact on marine productivity at the scale of the SO, using remote sensing data of iceberg occurrences and <span class="hlt">ocean</span> net primary productivity (NPP) covering the period 2002-2014. The impacts of both large and small icebergs are examined in four major ecological zones of the SO: the continental shelf zone (CSZ), the seasonal ice zone (SIZ), the permanent open <span class="hlt">ocean</span> zone (POOZ) and the polar front zone (PFZ). We found that both large and small icebergs have an observable positive impact on NPP, but their impacts vary in different zones. Small icebergs on average increase NPP in most iron deficient zones: by 21% for the SIZ, 16% for the POOZ, and 12% for the PFZ, but have relatively small effect in the CSZ where iron is supplied from melt water and sediment input from the continent. Large icebergs on average increase the NPP by about 10%. Their impacts are stronger at higher latitudes, where they are more concentrated. From 1992-2014, there is a significant increasing trend for both small and large icebergs. The increase was most rapid in the early 2000s, and has levelled off since then. As the climate continues to warm, the <span class="hlt">Antarctic</span> Ice Sheet is expected to experience increased mass loss as a whole, which could lead to more icebergs in the region. Based on our study, this could result in higher level of NPP in the SO as a whole, providing a negative feedback for global warming.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMPP23A1374K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMPP23A1374K"><span>Role of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> stratification in glacial atmospheric CO2 reduction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kobayashi, H.; Oka, A.</p> <p>2014-12-01</p> <p>Paleoclimate proxy data at the glacial period shows high salinity of more than 37.0 psu in the deep South Atlantic. At the same time, data also indicate that the residence time of the water mass was more than 3000 years. These data implies that the stratification by salinity was stronger in the deep <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (SO) in the Last Glacial Maximum (LGM). Previous studies using <span class="hlt">Ocean</span> General Circulation Model (OGCM) fail to explain the low glacial atmospheric carbon dioxide (CO2) concentration at LGM. The reproducibility of salinity and water mass age is considered insufficient in these OGCMs, which may in turn affect the reproducibility of the atmospheric CO2concentration. In coarse-resolution OGCMs, The deep water is formed by unrealistic open-<span class="hlt">ocean</span> deep convection in the SO. Considering these facts, we guessed previous studies using OGCM underestimated the salinity and water mass age at LGM. This study investigate the role of the enhanced stratification in the glacial SO on the variation of atmospheric CO2 concentration by using OGCM. In order to reproduce the recorded salinity of the deep water, relaxation of salinity toward value of recorded data is introduced in our OGCM simulations. It was found that deep water formation in East Antarctica is required for explaining the high salinity in the South Atlantic. In contrast, it is difficult to explain the glacial water mass age, even if we assume the situation vertical mixing is very weak in the SO. Contrary to previous estimate, the high salinity of the deep SO resulted in increase of <span class="hlt">Antarctic</span> Bottom water (AABW) flow and decrease the residence time of carbon in the deep <span class="hlt">ocean</span>, which increased atmospheric CO2 concentration. On the other hand, the weakening of the vertical mixing in the SO contributed to increase the vertical gradient of dissolved inorganic carbon (DIC), which decreased atmospheric CO2 concentration. Adding the contribution of the enhanced stratification in the glacial SO, we obtained larger</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSPC11B..05V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSPC11B..05V"><span>The <span class="hlt">ocean</span> mixed layer under <span class="hlt">Southern</span> <span class="hlt">Ocean</span> sea-ice: seasonal cycle and forcing.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Violaine, P.; Sallee, J. B.; Schmidtko, S.; Roquet, F.; Charrassin, J. B.</p> <p>2016-02-01</p> <p>The mixed-layer at the surface of the <span class="hlt">ocean</span> is the gateway for all exchanges between air and sea. A vast area of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is however seasonally capped by sea-ice, which alters this gateway and the characteristic the <span class="hlt">ocean</span> mixed-layer. The interaction between the <span class="hlt">ocean</span> mixed-layer and sea-ice plays a key role for water-mass formation and circulation, carbon cycle, sea-ice dynamics, and ultimately for the climate as a whole. However, the structure and characteristics of the mixed layer, as well as the processes responsible for its evolution, are poorly understood due to the lack of in-situ observations and measurements. We urgently need to better understand the forcing and the characteristics of the <span class="hlt">ocean</span> mixed-layer under sea-ice if we are to understand and predict the world's climate. In this study, we combine a range of distinct sources of observation to overcome this lack in our understanding of the Polar Regions. Working on Elephant Seal-derived data as well as ship-based observations and Argo float data, we describe the seasonal cycle of the characteristics and stability of the <span class="hlt">ocean</span> mixed layer over the entire <span class="hlt">Southern</span> <span class="hlt">Ocean</span> (South of 40°S), and specifically under sea-ice. Mixed-layer budgets of heat and freshwater are used to investigate the main forcings of the mixed-layer seasonal cycle. The seasonal variability of sea surface salinity and temperature are primarily driven by surface processes, dominated by sea-ice freshwater flux for the salt budget, and by air-sea flux for the heat budget. Ekman advection, vertical diffusivity and vertical entrainment play only secondary role.Our results suggest that changes in regional sea-ice distribution or sea-ice seasonal cycle duration, as currently observed, would widely affect the buoyancy budget of the underlying mixed-layer, and impacts large-scale water-mass formation and transformation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70035221','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70035221"><span>Pliocene three-dimensional global <span class="hlt">ocean</span> temperature reconstruction</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Dowsett, H.J.; Robinson, M.M.; Foley, K.M.</p> <p>2009-01-01</p> <p>The thermal structure of the mid-Piacenzian <span class="hlt">ocean</span> is obtained by combining the Pliocene Research, Interpretation and Synoptic Mapping Project (PRISM3) multiproxy sea-surface temperature (SST) reconstruction with bottom water temperature estimates from 27 locations produced using Mg/Ca paleothermometry based upon the ostracod genus Krithe. Deep water temperature estimates are skewed toward the Atlantic Basin (63% of the locations) and represent depths from 1000m to 4500 m. This reconstruction, meant to serve as a validation data set as well as an initialization for coupled numerical climate models, assumes a Pliocene water mass framework similar to that which exists today, with several important modifications. The area of formation of present day North Atlantic Deep Water (NADW) was expanded and extended further north toward the Arctic <span class="hlt">Ocean</span> during the mid-Piacenzian relative to today. This, combined with a deeper Greenland-Scotland Ridge, allowed a greater volume of warmer NADW to enter the Atlantic <span class="hlt">Ocean</span>. In the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, the Polar Front Zone was expanded relative to present day, but shifted closer to the <span class="hlt">Antarctic</span> continent. This, combined with at least seasonal reduction in sea ice extent, resulted in decreased <span class="hlt">Antarctic</span> Bottom Water (AABW) production (relative to present day) as well as possible changes in the depth of intermediate waters. The reconstructed mid-Piacenzian three-dimensional <span class="hlt">ocean</span> was warmer overall than today, and the hypothesized aerial extent of water masses appears to fit the limited stable isotopic data available for this time period. ?? Author(s) 2009.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018OcMod.123...98D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018OcMod.123...98D"><span>Understanding variability of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> overturning circulation in CORE-II models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Downes, S. M.; Spence, P.; Hogg, A. M.</p> <p>2018-03-01</p> <p>The current generation of climate models exhibit a large spread in the steady-state and projected <span class="hlt">Southern</span> <span class="hlt">Ocean</span> upper and lower overturning circulation, with mechanisms for deep <span class="hlt">ocean</span> variability remaining less well understood. Here, common <span class="hlt">Southern</span> <span class="hlt">Ocean</span> metrics in twelve models from the Coordinated <span class="hlt">Ocean</span>-ice Reference Experiment Phase II (CORE-II) are assessed over a 60 year period. Specifically, stratification, surface buoyancy fluxes, and eddies are linked to the magnitude of the strengthening trend in the upper overturning circulation, and a decreasing trend in the lower overturning circulation across the CORE-II models. The models evolve similarly in the upper 1 km and the deep <span class="hlt">ocean</span>, with an almost equivalent poleward intensification trend in the <span class="hlt">Southern</span> Hemisphere westerly winds. However, the models differ substantially in their eddy parameterisation and surface buoyancy fluxes. In general, models with a larger heat-driven water mass transformation where deep waters upwell at the surface ( ∼ 55°S) transport warmer waters into intermediate depths, thus weakening the stratification in the upper 2 km. Models with a weak eddy induced overturning and a warm bias in the intermediate waters are more likely to exhibit larger increases in the upper overturning circulation, and more significant weakening of the lower overturning circulation. We find the opposite holds for a cool model bias in intermediate depths, combined with a more complex 3D eddy parameterisation that acts to reduce isopycnal slope. In summary, the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> overturning circulation decadal trends in the coarse resolution CORE-II models are governed by biases in surface buoyancy fluxes and the <span class="hlt">ocean</span> density field, and the configuration of the eddy parameterisation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013DSRI...77...63S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013DSRI...77...63S"><span>Distribution and abundance of <span class="hlt">Antarctic</span> krill (Euphausia superba) along the <span class="hlt">Antarctic</span> Peninsula</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Siegel, Volker; Reiss, Christian S.; Dietrich, Kimberly S.; Haraldsson, Matilda; Rohardt, Gerhard</p> <p>2013-07-01</p> <p>Net-based data on the abundance, distribution, and demographic patterns of <span class="hlt">Antarctic</span> krill are quantified from a contemporaneous two ship survey of the <span class="hlt">Antarctic</span> Peninsula during austral summer 2011. Two survey areas were sampled focussed on Marguerite Bay in the south, and the tip of the <span class="hlt">Antarctic</span> Peninsula in the north. Data from 177 stations showed that the highest concentrations of krill were found in the <span class="hlt">southern</span> sampling area. Differences between areas were associated with a few large catches of one year old krill found in anomalously warm and productive waters in Marguerite Bay, and small krill catches in the less-productive, offshore waters in the north. Estimated krill density across the survey area was 3.4 krill m-2, and was low compared to the long-term average of 45 krill m-2 for the Elephant Island area. Overall recruitment between the two survey regions was similar, but per capita recruitment was about 60% lower than historical mean recruitment levels measured at Elephant Island since the late 1970s. Demographic patterns showed small krill concentrated near the coast, and large krill concentrated offshore on the shelf and slope all along the survey area. The offshore distribution of adult krill was delineated by the warm (˜1 °C), low salinity (33.8) water at 30 m, suggesting that most krill were present shoreward of the <span class="hlt">southern</span> boundary of <span class="hlt">Antarctic</span> Circumpolar Current Front. Distributions of larvae indicated that three hotspot areas were important for the production of krill: slope areas outside Marguerite Bay and north of the South Shetland Islands, and near the coast around <span class="hlt">Antarctic</span> Sound. Successful spawning, as inferred from larval abundance, was roughly coincident with the shelf break and not with inshore waters. Given the rapid changes in climate along the <span class="hlt">Antarctic</span> Peninsula and the lower per capita recruitment observed in recent years, studies comparing and contrasting production, growth, and recruitment across the Peninsula will be</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29018199','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29018199"><span>Pan-<span class="hlt">Antarctic</span> analysis aggregating spatial estimates of Adélie penguin abundance reveals robust dynamics despite stochastic noise.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Che-Castaldo, Christian; Jenouvrier, Stephanie; Youngflesh, Casey; Shoemaker, Kevin T; Humphries, Grant; McDowall, Philip; Landrum, Laura; Holland, Marika M; Li, Yun; Ji, Rubao; Lynch, Heather J</p> <p>2017-10-10</p> <p>Colonially-breeding seabirds have long served as indicator species for the health of the <span class="hlt">oceans</span> on which they depend. Abundance and breeding data are repeatedly collected at fixed study sites in the hopes that changes in abundance and productivity may be useful for adaptive management of marine resources, but their suitability for this purpose is often unknown. To address this, we fit a Bayesian population dynamics model that includes process and observation error to all known Adélie penguin abundance data (1982-2015) in the <span class="hlt">Antarctic</span>, covering >95% of their population globally. We find that process error exceeds observation error in this system, and that continent-wide "year effects" strongly influence population growth rates. Our findings have important implications for the use of Adélie penguins in <span class="hlt">Southern</span> <span class="hlt">Ocean</span> feedback management, and suggest that aggregating abundance across space provides the fastest reliable signal of true population change for species whose dynamics are driven by stochastic processes.Adélie penguins are a key <span class="hlt">Antarctic</span> indicator species, but data patchiness has challenged efforts to link population dynamics to key drivers. Che-Castaldo et al. resolve this issue using a pan-<span class="hlt">Antarctic</span> Bayesian model to infer missing data, and show that spatial aggregation leads to more robust inference regarding dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20080025048&hterms=Roms&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DRoms','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20080025048&hterms=Roms&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DRoms"><span><span class="hlt">Antarctic</span> Circumpolar Current Transport Variability during 2003-05 from GRACE</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zlotnicki, Victor; Wahr, John; Fukumori, Ichiro; Song, Yuhe T.</p> <p>2006-01-01</p> <p>Gravity Recovery and Climate Experiment (GRACE) gravity data spanning January 2003 - November 2005 are used as proxies for <span class="hlt">ocean</span> bottom pressure (BP) averaged over 1 month, spherical Gaussian caps 500 km in radius, and along paths bracketing the <span class="hlt">Antarctic</span> Circumpolar Current's various fronts. The GRACE BP signals are compared with those derived from the Estimating the Circulation and Climate of the <span class="hlt">Ocean</span> (ECCO) <span class="hlt">ocean</span> modeling-assimilation system, and to a non-Boussinesq version of the Regional <span class="hlt">Ocean</span> Model System (ROMS). The discrepancy found between GRACE and the models is 1.7 cm(sub H2O) (1 cm(sub H2O) similar to 1 hPa), slightly lower than the 1.9 cm(sub H2O) estimated by the authors independently from propagation of GRACE errors. The northern signals are weak and uncorrelated among basins. The <span class="hlt">southern</span> signals are strong, with a common seasonality. The seasonal cycle GRACE data observed in the Pacific and Indian <span class="hlt">Ocean</span> sectors of the ACC are consistent, with annual and semiannual amplitudes of 3.6 and 0.6 cm(sub H2O) (1.1 and 0.6 cm(sub H2O) with ECCO), the average over the full <span class="hlt">southern</span> path peaks (stronger ACC) in the <span class="hlt">southern</span> winter, on days of year 197 and 97 for the annual and semiannual components, respectively; the Atlantic <span class="hlt">Ocean</span> annual peak is 20 days earlier. An approximate conversion factor of 3.1 Sv ( Sv equivalent to 10(exp 6) m(exp 3) s(exp -1)) of barotropic transport variability per cm(sub H2O) of BP change is estimated. Wind stress data time series from the Quick Scatterometer (QuikSCAT), averaged monthly, zonally, and over the latitude band 40 de - 65 deg S, are also constructed and subsampled at the same months as with the GRACE data. The annual and semiannual harmonics of the wind stress peak on days 198 and 82, respectively. A decreasing trend over the 3 yr is observed in the three data types.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20070034064&hterms=Roms&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DRoms','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20070034064&hterms=Roms&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DRoms"><span><span class="hlt">Antarctic</span> Circumpolar Current Transport Variability during 2003-05 from GRACE</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zlotnicki, Victor; Wahr, John; Fukumori, Ichiro; Song, Yuhe T.</p> <p>2007-01-01</p> <p>Gravity Recovery and Climate Experiment (GRACE) gravity data spanning January 2003-November 2005 are used as proxies for <span class="hlt">ocean</span> bottom pressure (BP) averaged over 1 month, spherical Gaussian caps 500 km in radius, and along paths bracketing the <span class="hlt">Antarctic</span> Circumpolar Current's various fronts. The GRACE BP signals are compared with those derived from the Estimating the Circulation and Climate of the <span class="hlt">Ocean</span> (ECCO) <span class="hlt">ocean</span> modeling-assimilation system, and to a non-Boussinesq version of the Regional <span class="hlt">Ocean</span> Model System (ROMS). The discrepancy found between GRACE and the models is 1.7 cm<subscript>H2O (1 cm<subscript>H2O approx. 1 hPa), slightly lower than the 1.9 cmH2O estimated by the authors independently from propagation of GRACE errors. The northern signals are weak and uncorrelated among basins. The <span class="hlt">southern</span> signals are strong, with a common seasonality. The seasonal cycle GRACE data observed in the Pacific and Indian <span class="hlt">Ocean</span> sectors of the ACC are consistent, with annual and semiannual amplitudes of 3.6 and 0.6 cmH2O (1.1 and 0.6 cm<subscript>H2O with ECCO), the average over the full <span class="hlt">southern</span> path peaks (stronger ACC) in the <span class="hlt">southern</span> winter, on days of year 197 and 97 for the annual and semiannual components, respectively; the Atlantic <span class="hlt">Ocean</span> annual peak is 20 days earlier. An approximate conversion factor of 3.1 Sv (Sv equiv 10(exp 6)cu m/s) of barotropic transport variability per cm<subscript>H2O of BP change is estimated. Wind stress data time series from the Quick Scatterometer (QuikSCAT), averaged monthly, zonally, and over the latitude band 40(deg)- 65(deg)S, are also constructed and subsampled at the same months as with the GRACE data. The annual and semiannual harmonics of the wind stress peak on days 198 and 82, respectively. A decreasing trend over the 3 yr is observed in the three data types.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRC..122.8208L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRC..122.8208L"><span>Global <span class="hlt">Ocean</span> Vertical Velocity From a Dynamically Consistent <span class="hlt">Ocean</span> State Estimate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liang, Xinfeng; Spall, Michael; Wunsch, Carl</p> <p>2017-10-01</p> <p>Estimates of the global <span class="hlt">ocean</span> vertical velocities (Eulerian, eddy-induced, and residual) from a dynamically consistent and data-constrained <span class="hlt">ocean</span> state estimate are presented and analyzed. Conventional patterns of vertical velocity, Ekman pumping, appear in the upper <span class="hlt">ocean</span>, with topographic dominance at depth. Intense and vertically coherent upwelling and downwelling occur in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, which are likely due to the interaction of the <span class="hlt">Antarctic</span> Circumpolar Current and large-scale topographic features and are generally canceled out in the conventional zonally averaged results. These "elevators" at high latitudes connect the upper to the deep and abyssal <span class="hlt">oceans</span> and working together with isopycnal mixing are likely a mechanism, in addition to the formation of deep and abyssal waters, for fast responses of the deep and abyssal <span class="hlt">oceans</span> to the changing climate. Also, Eulerian and parameterized eddy-induced components are of opposite signs in numerous regions around the global <span class="hlt">ocean</span>, particularly in the <span class="hlt">ocean</span> interior away from surface and bottom. Nevertheless, residual vertical velocity is primarily determined by the Eulerian component, and related to winds and large-scale topographic features. The current estimates of vertical velocities can serve as a useful reference for investigating the vertical exchange of <span class="hlt">ocean</span> properties and tracers, and its complex spatial structure ultimately permits regional tests of basic oceanographic concepts such as Sverdrup balance and coastal upwelling/downwelling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMPP43B1352N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMPP43B1352N"><span>Cryptic outgassing from the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> during the Holocene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nichols, J. E.; Moy, C. M.; Peteet, D. M.; Vandergoes, M.; Curtin, L.; Gilmer, G.</p> <p>2017-12-01</p> <p>The <span class="hlt">Southern</span> <span class="hlt">Ocean</span> is an important pre-anthropogenic source of carbon to the atmosphere. When <span class="hlt">Southern</span> Hemisphere Westerly Winds are shifted poleward, wind-driven upwelling brings carbon-rich deep water to the surface. Multiple studies have shown that this mechanism is particularly important during the last deglaciation and is partly influenced by climate and oceanographic change triggered by the Northern Hemisphere high latitudes and the tropics. Here we show that the middle Holocene, too, was an important time for increased upwelling. New paleoecological reconstructions, inorganic and organic geochemical data, and stable isotope data from lakes and peatlands on New Zealand's South Island and Subantarctic Islands show strong evidence for poleward-shifted <span class="hlt">Southern</span> Hemisphere Westerly Winds during the middle Holocene. Warming in the northern hemisphere either weakens westerlies or shifts them southward, reinvigorating the CO2 outgassing from the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. However, if, like in the deglacial period, the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> was a source of carbon to the atmosphere in the middle Holocene, why do we not see ice-core evidence for increased pCO2 of the atmosphere? To answer this question, we look north, to the peatlands of the sub-Boreal, Boreal, and Arctic regions. We find, using a new compilation of peatland carbon accumulation rate data, that the northern peatland carbon sink, which was not a factor in the deglacial carbon cycle, could be strong enough in the mid Holocene to counterbalance the increased outgassing. The peatland carbon sink is strongest at the same time as our records from the subantarctic show that the SHWW are in a weakened or poleward-shifted state. Our work shows how the subantarctic has revealed a globally important mechanism impacting the carbon cycle of the Holocene.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PalOc..31..131B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PalOc..31..131B"><span>Environmental responses of the Northeast <span class="hlt">Antarctic</span> Peninsula to the Holocene climate variability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barbara, Loïc.; Crosta, Xavier; Leventer, Amy; Schmidt, Sabine; Etourneau, Johan; Domack, Eugene; Massé, Guillaume</p> <p>2016-01-01</p> <p>In this study, we present a unique high-resolution Holocene record of oceanographic and climatic change based on analyses of diatom assemblages combined with biomarker data from a sediment core collected from the Vega Drift, eastern <span class="hlt">Antarctic</span> Peninsula (EAP). These data add to the climate framework already established by high-resolution marine sedimentary records from the Palmer Deep, western <span class="hlt">Antarctic</span> Peninsula (WAP). Heavy sea ice conditions and reduced primary productivity were observed prior to 7.4 ka B.P. in relation with the proximity of the glacial ice melt and calving. Subsequent Holocene oceanographic conditions were controlled by the interactions between the Westerlies-<span class="hlt">Antarctic</span> Circumpolar Current (ACC)-Weddell Gyre dynamics. A warm period characterized by short seasonal sea ice duration associated with a <span class="hlt">southern</span> shift of both ACC and Westerlies field persisted until 5 ka B.P. This warm episode was then followed by climate deterioration during the middle-to-late Holocene (5 to 1.9 ka B.P.) with a gradual increase in annual sea ice duration triggered by the expansion of the Weddell Gyre and a strong <span class="hlt">oceanic</span> connection from the EAP to the WAP. Increase of benthic diatom species during this period was indicative of more summer/autumn storms, which was consistent with changes in synoptic atmospheric circulation and the establishment of low- to high-latitude teleconnections. Finally, the multicentennial scale variability of the Weddell Gyre intensity and storm frequency during the late Holocene appeared to be associated with the increased El Niño-<span class="hlt">Southern</span> Oscillation frequency.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1438736','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1438736"><span>Global Climate Impacts of Fixing the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Shortwave Radiation Bias in the Community Earth System Model (CESM)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Kay, Jennifer E.; Wall, Casey; Yettella, Vineel</p> <p></p> <p>Here, a large, long-standing, and pervasive climate model bias is excessive absorbed shortwave radiation (ASR) over the midlatitude <span class="hlt">oceans</span>, especially the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. This study investigates both the underlying mechanisms for and climate impacts of this bias within the Community Earth System Model, version 1, with the Community Atmosphere Model, version 5 [CESM1(CAM5)]. Excessive <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ASR in CESM1(CAM5) results in part because low-level clouds contain insufficient amounts of supercooled liquid. In a present-day atmosphere-only run, an observationally motivated modification to the shallow convection detrainment increases supercooled cloud liquid, brightens low-level clouds, and substantially reduces the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ASR bias.more » Tuning to maintain global energy balance enables reduction of a compensating tropical ASR bias. In the resulting preindustrial fully coupled run with a brighter <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and dimmer tropics, the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> cools and the tropics warm. As a result of the enhanced meridional temperature gradient, poleward heat transport increases in both hemispheres (especially the <span class="hlt">Southern</span> Hemisphere), and the <span class="hlt">Southern</span> Hemisphere atmospheric jet strengthens. Because northward cross-equatorial heat transport reductions occur primarily in the <span class="hlt">ocean</span> (80%), not the atmosphere (20%), a proposed atmospheric teleconnection linking <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ASR bias reduction and cooling with northward shifts in tropical precipitation has little impact. In summary, observationally motivated supercooled liquid water increases in shallow convective clouds enable large reductions in long-standing climate model shortwave radiation biases. Of relevance to both model bias reduction and climate dynamics, quantifying the influence of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> cooling on tropical precipitation requires a model with dynamic <span class="hlt">ocean</span> heat transport.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1438736-global-climate-impacts-fixing-southern-ocean-shortwave-radiation-bias-community-earth-system-model-cesm','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1438736-global-climate-impacts-fixing-southern-ocean-shortwave-radiation-bias-community-earth-system-model-cesm"><span>Global Climate Impacts of Fixing the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> Shortwave Radiation Bias in the Community Earth System Model (CESM)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Kay, Jennifer E.; Wall, Casey; Yettella, Vineel; ...</p> <p>2016-06-10</p> <p>Here, a large, long-standing, and pervasive climate model bias is excessive absorbed shortwave radiation (ASR) over the midlatitude <span class="hlt">oceans</span>, especially the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>. This study investigates both the underlying mechanisms for and climate impacts of this bias within the Community Earth System Model, version 1, with the Community Atmosphere Model, version 5 [CESM1(CAM5)]. Excessive <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ASR in CESM1(CAM5) results in part because low-level clouds contain insufficient amounts of supercooled liquid. In a present-day atmosphere-only run, an observationally motivated modification to the shallow convection detrainment increases supercooled cloud liquid, brightens low-level clouds, and substantially reduces the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ASR bias.more » Tuning to maintain global energy balance enables reduction of a compensating tropical ASR bias. In the resulting preindustrial fully coupled run with a brighter <span class="hlt">Southern</span> <span class="hlt">Ocean</span> and dimmer tropics, the <span class="hlt">Southern</span> <span class="hlt">Ocean</span> cools and the tropics warm. As a result of the enhanced meridional temperature gradient, poleward heat transport increases in both hemispheres (especially the <span class="hlt">Southern</span> Hemisphere), and the <span class="hlt">Southern</span> Hemisphere atmospheric jet strengthens. Because northward cross-equatorial heat transport reductions occur primarily in the <span class="hlt">ocean</span> (80%), not the atmosphere (20%), a proposed atmospheric teleconnection linking <span class="hlt">Southern</span> <span class="hlt">Ocean</span> ASR bias reduction and cooling with northward shifts in tropical precipitation has little impact. In summary, observationally motivated supercooled liquid water increases in shallow convective clouds enable large reductions in long-standing climate model shortwave radiation biases. Of relevance to both model bias reduction and climate dynamics, quantifying the influence of <span class="hlt">Southern</span> <span class="hlt">Ocean</span> cooling on tropical precipitation requires a model with dynamic <span class="hlt">ocean</span> heat transport.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017BGeo...14.5217C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017BGeo...14.5217C"><span>Carbon uptake and biogeochemical change in the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, south of Tasmania</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Conde Pardo, Paula; Tilbrook, Bronte; Langlais, Clothilde; Trull, Thomas William; Rich Rintoul, Stephen</p> <p>2017-11-01</p> <p>Biogeochemical change in the water masses of the <span class="hlt">Southern</span> <span class="hlt">Ocean</span>, south of Tasmania, was assessed for the 16-year period between 1995 and 2011 using data from four summer repeats of the WOCE-JGOFS-CLIVAR-GO-SHIP (Key et al., 2015; Olsen et al., 2016) SR03 hydrographic section (at ˜ 140° E). Changes in temperature, salinity, oxygen, and nutrients were used to disentangle the effect of solubility, biology, circulation and anthropogenic carbon (CANT) uptake on the variability of dissolved inorganic carbon (DIC) for eight water mass layers defined by neutral surfaces (γn). CANT was estimated using an improved back-calculation method. Warming (˜ 0.0352 ± 0.0170 °C yr-1) of Subtropical Central Water (STCW) and <span class="hlt">Antarctic</span> Surface Water (AASW) layers decreased their gas solubility, and accordingly DIC concentrations increased less rapidly than expected from equilibration with rising atmospheric CO2 (˜ 0.86 ± 0.16 µmol kg-1 yr-1 versus ˜ 1 ± 0.12 µmol kg-1 yr-1). An increase in apparent oxygen utilisation (AOU) occurred in these layers due to either remineralisation of organic matter or intensification of upwelling. The range of estimates for the increases in CANT were 0.71 ± 0.08 to 0.93 ± 0.08 µmol kg-1 yr-1 for STCW and 0.35 ± 0.14 to 0.65 ± 0.21 µmol kg-1 yr-1 for AASW, with the lower values in each water mass obtained by assigning all the AOU change to remineralisation. DIC increases in the Sub-<span class="hlt">Antarctic</span> Mode Water (SAMW, 1.10 ± 0.14 µmol kg-1 yr-1) and <span class="hlt">Antarctic</span> Intermediate Water (AAIW, 0.40 ± 0.15 µmol kg-1 yr-1) layers were similar to the calculated CANT trends. For SAMW, the CANT increase tracked rising atmospheric CO2. As a consequence of the general DIC increase, decreases in total pH (pHT) and aragonite saturation (ΩAr) were found in most water masses, with the upper <span class="hlt">ocean</span> and the SAMW layer presenting the largest trends for pHT decrease (˜ -0.0031 ± 0.0004 yr-1). DIC increases in deep and bottom layers (˜ 0.24 ± 0.04 µmol kg-1 yr-1</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <div class="footer-extlink text-muted" style="margin-bottom:1rem; text-align:center;">Some links on this page may take you to non-federal websites. 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