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Sample records for global ocean storage

  1. Global ocean storage of anthropogenic carbon

    NASA Astrophysics Data System (ADS)

    Khatiwala, S.; Tanhua, T.; Mikaloff Fletcher, S.; Gerber, M.; Doney, S. C.; Graven, H. D.; Gruber, N.; McKinley, G. A.; Murata, A.; Ríos, A. F.; Sabine, C. L.

    2013-04-01

    The global ocean is a significant sink for anthropogenic carbon (Cant), absorbing roughly a third of human CO2 emitted over the industrial period. Robust estimates of the magnitude and variability of the storage and distribution of Cant in the ocean are therefore important for understanding the human impact on climate. In this synthesis we review observational and model-based estimates of the storage and transport of Cant in the ocean. We pay particular attention to the uncertainties and potential biases inherent in different inference schemes. On a global scale, three data-based estimates of the distribution and inventory of Cant are now available. While the inventories are found to agree within their uncertainty, there are considerable differences in the spatial distribution. We also present a review of the progress made in the application of inverse and data assimilation techniques which combine ocean interior estimates of Cant with numerical ocean circulation models. Such methods are especially useful for estimating the air-sea flux and interior transport of Cant, quantities that are otherwise difficult to observe directly. However, the results are found to be highly dependent on modeled circulation, with the spread due to different ocean models at least as large as that from the different observational methods used to estimate Cant. Our review also highlights the importance of repeat measurements of hydrographic and biogeochemical parameters to estimate the storage of Cant on decadal timescales in the presence of the variability in circulation that is neglected by other approaches. Data-based Cant estimates provide important constraints on forward ocean models, which exhibit both broad similarities and regional errors relative to the observational fields. A compilation of inventories of Cant gives us a "best" estimate of the global ocean inventory of anthropogenic carbon in 2010 of 155 ± 31 PgC (±20% uncertainty). This estimate includes a broad range of

  2. Global ocean storage of anthropogenic carbon

    NASA Astrophysics Data System (ADS)

    Khatiwala, S.; Tanhua, T.; Mikaloff Fletcher, S.; Gerber, M.; Doney, S. C.; Graven, H. D.; Gruber, N.; McKinley, G. A.; Murata, A.; Ríos, A. F.; Sabine, C. L.; Sarmiento, J. L.

    2012-07-01

    The global ocean is a significant sink for anthropogenic carbon (Cant), absorbing roughly a third of human CO2 emitted over the industrial period. Robust estimates of the magnitude and variability of the storage and distribution of Cant in the ocean are therefore important for understanding the human impact on climate. In this synthesis we review observational and model-based estimates of the storage and transport of Cant in the ocean. We pay particular attention to the uncertainties and potential biases inherent in different inference schemes. On a global scale, three data based estimates of the distribution and inventory of Cant are now available. While the inventories are found to agree within their uncertainty, there are considerable differences in the spatial distribution. We also present a review of the progress made in the application of inverse and data-assimilation techniques which combine ocean interior estimates of Cant with numerical ocean circulation models. Such methods are especially useful for estimating the air-sea flux and interior transport of Cant, quantities that are otherwise difficult to observe directly. However, the results are found to be highly dependent on modeled circulation, with the spread due to different ocean models at least as large as that from the different observational methods used to estimate Cant. Our review also highlights the importance of repeat measurements of hydrographic and biogeochemical parameters to estimate the storage of Cant on decadal timescales in the presence of the variability in circulation that is neglected by other approaches. Data-based Cant estimates provide important constraints on ocean forward models, which exhibit both broad similarities and regional errors relative to the observational fields. A compilation of inventories of Cant gives us a "best" estimate of the global ocean inventory of anthropogenic carbon in 2010 of 155 Pg C with an uncertainty of ±20%. This estimate includes a broad range of

  3. Global Ocean Storage of Anthropogenic Carbon (GOSAC)

    SciTech Connect

    Orr, J C

    2002-04-02

    GOSAC was an EC-funded project (1998-2001) focused on improving the predictive capacity and accelerating development of global-scale, three-dimensional, ocean carbon-cycle models by means of standardized model evaluation and model intercomparison. Through the EC Environment and Climate Programme, GOSAC supported the participation of seven European modeling groups in the second phase of the larger international effort OCMIP (the Ocean Carbon-Cycle Model Intercomparison Project). OCMIP included model comparison and validation for both CO{sub 2} and other ocean circulation and biogeochemical tracers. Beyond the international OCMIP effort, GOSAC also supported the same EC ocean carbon cycle modeling groups to make simulations to evaluate the efficiency of purposeful sequestration of CO{sub 2} in the ocean. Such sequestration, below the thermocline has been proposed as a strategy to help mitigate the increase of CO{sub 2} in the atmosphere. Some technical and scientific highlights of GOSAC are given.

  4. Global upper ocean heat storage response to radiative forcing from changing solar irradiance and increasing greenhouse gas/aerosol concentrations

    NASA Astrophysics Data System (ADS)

    White, Warren B.; Cayan, Daniel R.; Lean, Judith

    1998-09-01

    We constructed gridded fields of diabatic heat storage changes in the upper ocean from 20°S to 60°N from historical temperature profiles collected from 1955 to 1996. We filtered these 42 year records for periods of 8 to 15 years and 15 to 30 years, producing depth-weighted vertical average temperature (DVT) changes from the sea surface to the top of the main pycnocline. Basin and global averages of these DVT changes reveal decadal and interdecadal variability in phase across the Indian, Pacific, Atlantic, and Global Oceans, each significantly correlated with changing surface solar radiative forcing at a lag of 0+/-2 years. Decadal and interdecadal changes in global average DVT are 0.06°+/-0.01°K and 0.04°K+/-0.01°K, respectively, the same as those expected from consideration of the Stefan-Boltzmann radiation balance (i.e., 0.3°K per Wm-2) in response to 0.1% changes in surface solar radiative forcing of 0.2 Wm-2 and 0.15 Wm-2, respectively. Global spatial patterns of DVT changes are similar to temperature changes simulated in coupled ocean-atmosphere models, suggesting that natural modes of Earth's variability are phase-locked to the solar irradiance cycle. A trend in global average DVT of 0.15°K over this 42 year record cannot be explained by changing surface solar radiative forcing. But when we consider the 0.5 Wm-2 increase in surface radiative forcing estimated from the increase in atmospheric greenhouse gas and aerosol (GGA) concentrations over this period [Intergovernmental Panel on Climate Change, 1995], the Stefan-Boltzmann radiation balance yields this observed change. Moreover, the sum of solar and GGA surface radiative forcing can explain the relatively sharp increase in global and basin average DVT in the late 1970's.

  5. Microbial Carbon Pump ---A New Mechanism for Long-Term Carbon Storage in the Global Ocean (Invited)

    NASA Astrophysics Data System (ADS)

    Jiao, N.; Azam, F.; McP Working Group; Scor Wg134

    2010-12-01

    to a recalcitrant carbon reservoir, pumping organic carbon from low concentrations of labile DOM to high concentrations of recalcitrant DOM, building up a huge reservoir for carbon storage over time. Meanwhile the MCP transfers more carbon relative to nitrogen and phosphorus from the reactive organic matter pool into recalcitrant organic matter pool. Compared with the solubility pump, an abiotic mechanism for carbon storage in the ocean which has ocean acidification impacts on marine organisms and biogeochemical cycles, the MCP-driven recalcitrant DOM carbon storage does not appreciably alter the buffering capacity of seawater and has no known negative impact on marine organisms. Furthermore, in the ocean warming scenario, the partitioning of biogenic carbon flow will change, with the flow to POM diminishing and that to DOM increasing, and thus the role of the MCP in carbon storage will most likely enhanced. A working group joined by 26 scientists from 12 countries has been formed under the Scientific Committee for Oceanic Research (SCOR-WG134) to address this multi-faceted biogeochemical issue related to carbon cycling in the ocean and global climate changes.

  6. Global Ocean Phytoplankton

    NASA Technical Reports Server (NTRS)

    Franz, B. A.; Behrenfeld, M. J.; Siegel, D. A.; Werdell, P. J.

    2013-01-01

    Phytoplankton are free-floating algae that grow in the euphotic zone of the upper ocean, converting carbon dioxide, sunlight, and available nutrients into organic carbon through photosynthesis. Despite their microscopic size, these photoautotrophs are responsible for roughly half the net primary production on Earth (NPP; gross primary production minus respiration), fixing atmospheric CO2 into food that fuels our global ocean ecosystems. Phytoplankton thus play a critical role in the global carbon cycle, and their growth patterns are highly sensitive to environmental changes such as increased ocean temperatures that stratify the water column and prohibit the transfer of cold, nutrient richwaters to the upper ocean euphotic zone.

  7. Global Ocean Phytoplankton

    NASA Technical Reports Server (NTRS)

    Franz, B. A.; Behrenfeld, M. J.; Siegel, D. A.; Werdell, P. J.

    2014-01-01

    Marine phytoplankton are responsible for roughly half the net primary production (NPP) on Earth, fixing atmospheric CO2 into food that fuels global ocean ecosystems and drives the ocean's biogeochemical cycles. Phytoplankton growth is highly sensitive to variations in ocean physical properties, such as upper ocean stratification and light availability within this mixed layer. Satellite ocean color sensors, such as the Sea-viewing Wide Field-of-view Sensor (SeaWiFS; McClain 2009) and Moderate Resolution Imaging Spectroradiometer (MODIS; Esaias 1998), provide observations of sufficient frequency and geographic coverage to globally monitor physically-driven changes in phytoplankton distributions. In practice, ocean color sensors retrieve the spectral distribution of visible solar radiation reflected upward from beneath the ocean surface, which can then be related to changes in the photosynthetic phytoplankton pigment, chlorophyll- a (Chla; measured in mg m-3). Here, global Chla data for 2013 are evaluated within the context of the 16-year continuous record provided through the combined observations of SeaWiFS (1997-2010) and MODIS on Aqua (MODISA; 2002-present). Ocean color measurements from the recently launched Visible and Infrared Imaging Radiometer Suite (VIIRS; 2011-present) are also considered, but results suggest that the temporal calibration of the VIIRS sensor is not yet sufficiently stable for quantitative global change studies. All MODISA (version 2013.1), SeaWiFS (version 2010.0), and VIIRS (version 2013.1) data presented here were produced by NASA using consistent Chla algorithms.

  8. The effect of ocean acidification on carbon storage and sequestration in seagrass beds; a global and UK context.

    PubMed

    Garrard, Samantha L; Beaumont, Nicola J

    2014-09-15

    Ocean acidification will have many negative consequences for marine organisms and ecosystems, leading to a decline in many ecosystem services provided by the marine environment. This study reviews the effect of ocean acidification (OA) on seagrasses, assessing how this may affect their capacity to sequester carbon in the future and providing an economic valuation of these changes. If ocean acidification leads to a significant increase in above- and below-ground biomass, the capacity of seagrass to sequester carbon will be significantly increased. The associated value of this increase in sequestration capacity is approximately £500 and 600 billion globally between 2010 and 2100. A proportionally similar increase in carbon sequestration value was found for the UK. This study highlights one of the few positive stories for ocean acidification and underlines that sustainable management of seagrasses is critical to avoid their continued degradation and loss of carbon sequestration capacity. PMID:25103900

  9. Freshwater and its role in the Arctic Marine System: Sources, disposition, storage, export, and physical and biogeochemical consequences in the Arctic and global oceans

    NASA Astrophysics Data System (ADS)

    Carmack, E. C.; Yamamoto-Kawai, M.; Haine, T. W. N.; Bacon, S.; Bluhm, B. A.; Lique, C.; Melling, H.; Polyakov, I. V.; Straneo, F.; Timmermans, M.-L.; Williams, W. J.

    2016-03-01

    The Arctic Ocean is a fundamental node in the global hydrological cycle and the ocean's thermohaline circulation. We here assess the system's key functions and processes: (1) the delivery of fresh and low-salinity waters to the Arctic Ocean by river inflow, net precipitation, distillation during the freeze/thaw cycle, and Pacific Ocean inflows; (2) the disposition (e.g., sources, pathways, and storage) of freshwater components within the Arctic Ocean; and (3) the release and export of freshwater components into the bordering convective domains of the North Atlantic. We then examine physical, chemical, or biological processes which are influenced or constrained by the local quantities and geochemical qualities of freshwater; these include stratification and vertical mixing, ocean heat flux, nutrient supply, primary production, ocean acidification, and biogeochemical cycling. Internal to the Arctic the joint effects of sea ice decline and hydrological cycle intensification have strengthened coupling between the ocean and the atmosphere (e.g., wind and ice drift stresses, solar radiation, and heat and moisture exchange), the bordering drainage basins (e.g., river discharge, sediment transport, and erosion), and terrestrial ecosystems (e.g., Arctic greening, dissolved and particulate carbon loading, and altered phenology of biotic components). External to the Arctic freshwater export acts as both a constraint to and a necessary ingredient for deep convection in the bordering subarctic gyres and thus affects the global thermohaline circulation. Geochemical fingerprints attained within the Arctic Ocean are likewise exported into the neighboring subarctic systems and beyond. Finally, we discuss observed and modeled functions and changes in this system on seasonal, annual, and decadal time scales and discuss mechanisms that link the marine system to atmospheric, terrestrial, and cryospheric systems.

  10. The Global Ocean Observing System

    NASA Technical Reports Server (NTRS)

    Kester, Dana

    1992-01-01

    A Global Ocean Observing System (GOOS) should be established now with international coordination (1) to address issues of global change, (2) to implement operational ENSO forecasts, (3) to provide the data required to apply global ocean circulation models, and (4) to extract the greatest value from the one billion dollar investment over the next ten years in ocean remote sensing by the world's space agencies. The objectives of GOOS will focus on climatic and oceanic predictions, on assessing coastal pollution, and in determining the sustainability of living marine resources and ecosystems. GOOS will be a complete system including satellite observations, in situ observations, numerical modeling of ocean processes, and data exchange and management. A series of practical and economic benefits will be derived from the information generated by GOOS. In addition to the marine science community, these benefits will be realized by the energy industries of the world, and by the world's fisheries. The basic oceanic variables that are required to meet the oceanic and predictability objectives of GOOS include wind velocity over the ocean, sea surface temperature and salinity, oceanic profiles of temperature and salinity, surface current, sea level, the extent and thickness of sea ice, the partial pressure of CO2 in surface waters, and the chlorophyll concentration of surface waters. Ocean circulation models and coupled ocean-atmosphere models can be used to evaluate observing system design, to assimilate diverse data sets from in situ and remotely sensed observations, and ultimately to predict future states of the system. The volume of ocean data will increase enormously over the next decade as new satellite systems are launched and as complementary in situ measuring systems are deployed. These data must be transmitted, quality controlled, exchanged, analyzed, and archived with the best state-of-the-art computational methods.

  11. The global ocean microbiome.

    PubMed

    Moran, Mary Ann

    2015-12-11

    The microbiome of the largest environment on Earth has been gradually revealing its secrets over four decades of study. Despite the dispersed nature of substrates and the transience of surfaces, marine microbes drive essential transformations in all global elemental cycles. Much has been learned about the microbes that carry out key biogeochemical processes, but there are still plenty of ambiguities about the factors important in regulating activity, including the role of microbial interactions. Identifying the molecular "currencies" exchanged within the microbial community will provide key information on microbiome function and its vulnerability to environmental change. PMID:26659059

  12. Modelling the global coastal ocean.

    PubMed

    Holt, Jason; Harle, James; Proctor, Roger; Michel, Sylvain; Ashworth, Mike; Batstone, Crispian; Allen, Icarus; Holmes, Robert; Smyth, Tim; Haines, Keith; Bretherton, Dan; Smith, Gregory

    2009-03-13

    Shelf and coastal seas are regions of exceptionally high biological productivity, high rates of biogeochemical cycling and immense socio-economic importance. They are, however, poorly represented by the present generation of Earth system models, both in terms of resolution and process representation. Hence, these models cannot be used to elucidate the role of the coastal ocean in global biogeochemical cycles and the effects global change (both direct anthropogenic and climatic) are having on them. Here, we present a system for simulating all the coastal regions around the world (the Global Coastal Ocean Modelling System) in a systematic and practical fashion. It is based on automatically generating multiple nested model domains, using the Proudman Oceanographic Laboratory Coastal Ocean Modelling System coupled to the European Regional Seas Ecosystem Model. Preliminary results from the system are presented. These demonstrate the viability of the concept, and we discuss the prospects for using the system to explore key areas of global change in shelf seas, such as their role in the carbon cycle and climate change effects on fisheries. PMID:19087928

  13. Global ocean circulation by altimetry

    NASA Technical Reports Server (NTRS)

    Wunsch, Carl; Haidvogel, D.

    1991-01-01

    The overall objectives of this project are to determine the general circulation of the oceans and many of its climate and biochemical consequences through the optimum use of altimetry data from TOPEX/POSEIDON and related missions. Emphasis is on the global-scale circulation, as opposed to the regional scale, but some more local studies will be carried out. Because of funding limitations, the primary initial focus will be on the time-dependent global-scale circulation rather than the mean; eventually, the mean circulation must be dealt with as well.

  14. Ecosystem and Societal Consequences of Ocean versus Atmosphere Carbon Storage

    NASA Astrophysics Data System (ADS)

    Barry, J. P.; Adams, E. E.; Bleck, R.; Caldeira, K.; Carman, K.; Erickson, D.; Kennett, J. P.; Sarmiento, J. L.; Tsouris, C.

    2005-12-01

    Climate stabilization during the next 100 to 200 y will require significant reductions in atmospheric carbon dioxide emissions to avoid large increases in global temperature. While there is only mild disagreement concerning carbon management options such as energy efficiency, alternative energy sources, and even geologic C storage, ocean storage remains controversial, due to its potential impacts for deep-sea ecosystems. A cautionary approach to carbon management might avoid any ocean C storage. However, this approach does not consider the balance between ocean and terrestrial ecosystems, or societal concerns. Using a broader perspective, we might ask whether atmospheric CO2 storage (i.e. the status quo), or deep ocean sequestration is better for Earth's ecosystems and societies? We explored the potential storage capacity of the deep ocean for carbon dioxide, under scenarios producing a 0.2 pH unit reduction, a level similar to observed scale of pH variability in deep ocean basins, which may also represent coarse thresholds for deep-sea ecosystem impacts. Roughly 500 PgC could be stored in the deep ocean to lower pH by 0.2 units, yielding a long term (~250 y) ocean sequestration program of 2 PgCy-1. The mitigation value of such ocean C sequestration for upper ocean and terrestrial systems depends strongly on future emission scenarios. Under a low emission scenario (e.g. SRES scenario A1T, B1; atm CO2 ~575 ppm, global temperature change of ~+2 oC), a 2 PgCy-1 ocean CO2 injection program could mitigate global temperature by ~-0.4 oC (20%) by 2100. This could reduce significantly the number of people at risk of water shortage and tropical diseases, with lesser improvement expected for hunger or coastal flooding. Mitigation for terrestrial and shallow ocean ecosystems is difficult to predict. A 0.4 oC reduction in warming this century is expected to delay the progression of coral reef devastation by roughly 20 y. The mitigation potential of ocean storage under very

  15. Enhanced deep ocean ventilation and oxygenation with global warming

    NASA Astrophysics Data System (ADS)

    Froelicher, T. L.; Jaccard, S.; Dunne, J. P.; Paynter, D.; Gruber, N.

    2014-12-01

    Twenty-first century coupled climate model simulations, observations from the recent past, and theoretical arguments suggest a consistent trend towards warmer ocean temperatures and fresher polar surface oceans in response to increased radiative forcing resulting in increased upper ocean stratification and reduced ventilation and oxygenation of the deep ocean. 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 ocean 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 ocean is actually better ventilated and oxygenated in a future warmer equilibrated climate consistent with paleo-proxy records. The enhanced deep ocean ventilation in the Southern Ocean occurs in spite of increased positive surface buoyancy fluxes and a constancy of the Southern Hemisphere westerly winds - circumstances that would otherwise be expected to lead to a reduction in deep ocean 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 ocean to the Southern Ocean interior on multi-century timescales. The subsequent upwelling of salinity-rich waters in the Southern Ocean strips away the freshwater cap that maintains vertical stability and increases open ocean convection and the formation of Antarctic Bottom Waters. As a result, the global ocean oxygen content and the nutrient supply from the deep ocean to the surface are higher in a warmer ocean. The implications for past and future changes in ocean heat and carbon storage will be discussed.

  16. Monitoring ocean heat content from the current generation of global ocean observing systems

    NASA Astrophysics Data System (ADS)

    von Schuckmann, K.; Sallée, J.-B.; Chambers, D.; Le Traon, P.-Y.; Cabanes, C.; Gaillard, F.; Speich, S.; Hamon, M.

    2013-06-01

    Variations in the world's ocean heat storage and its associated volume changes are a key factor to gauge global warming and to assess the Earth's energy budget. It is also directly link to sea level change, which has a direct impact on coastal populations. Understanding and monitoring heat and sea level change is therefore one of the major legacies of current global ocean observing systems. In this study, we present an inter-comparison of the three of these global ocean observing systems: the ocean temperature/salinity network Argo, the gravimeter GRACE and the satellite altimeters. Their consistency is investigated at global and regional scale during the period 2005-2010 of overlapping time window of re-qualified data. These three datasets allow closing the recent global ocean sea level budget within uncertainties. However, sampling inconsistencies need to be corrected for an accurate budget at global scale. The Argo network allows estimating global ocean heat content and global sea level and reveals a positive change of 0.5 ± 0.1W m-2 and 0.5 ± 0.1 mm yr-1 over the last 8 yr (2005-2012). Regional inter-comparison of the global observing systems highlights the importance of specific ocean basins for the global estimates. Specifically, the Indonesian Archipelago appears as a key region for the global ocean variability. Both the large regional variability and the uncertainties in the current observing systems, prevent us to shed light, from the global sea level perspective, on the climatically important deep ocean changes. This emphasises, once more, the importance of continuing sustained effort in measuring the deep ocean from ship platforms and by setting up a much needed automated deep-Argo network.

  17. A global distributed storage architecture

    NASA Technical Reports Server (NTRS)

    Lionikis, Nemo M.; Shields, Michael F.

    1996-01-01

    NSA architects and planners have come to realize that to gain the maximum benefit from, and keep pace with, emerging technologies, we must move to a radically different computing architecture. The compute complex of the future will be a distributed heterogeneous environment, where, to a much greater extent than today, network-based services are invoked to obtain resources. Among the rewards of implementing the services-based view are that it insulates the user from much of the complexity of our multi-platform, networked, computer and storage environment and hides its diverse underlying implementation details. In this paper, we will describe one of the fundamental services being built in our envisioned infrastructure; a global, distributed archive with near-real-time access characteristics. Our approach for adapting mass storage services to this infrastructure will become clear as the service is discussed.

  18. Decadal Changes in Global Ocean Chlorophyll

    NASA Technical Reports Server (NTRS)

    Gregg, Watson W.; Conkright, Margarita E.; Koblinsky, Chester J. (Technical Monitor)

    2001-01-01

    The global ocean chlorophyll archive produced by the Coastal Zone Color Scanner (CZCS) was revised using compatible algorithms with the Sea-viewing Wide Field-of-view Sensor (SeaWIFS), and both were blended with in situ data. This methodology permitted a quantitative comparison of decadal changes in global ocean chlorophyll from the CZCS (1979-1986) and SeaWiFS (Sep. 1997-Dec. 2000) records. Global seasonal means of ocean chlorophyll decreased over the two observational segments, by 8% in winter to 16% in autumn. Chlorophyll in the high latitudes was responsible for most of the decadal change. Conversely, chlorophyll concentrations in the low latitudes increased. The differences and similarities of the two data records provide evidence of how the Earth's climate may be changing and how ocean biota respond. Furthermore, the results have implications for the ocean carbon cycle.

  19. Notes on global climate and ocean currents

    NASA Astrophysics Data System (ADS)

    Nigmatulin, R. I.

    2012-02-01

    The problems related to the role of both natural and anthropogenic factors in global climate change are considered. The role of ocean circulation in the Earth's global thermodynamic processes is qualitatively analyzed. The balances of greenhouse gases in the atmosphere and in the ocean and the effect of anthropogenic factors are analyzed. The requirements for new-generation models of the Earth's climate are formulated.

  20. Global warming and changes in ocean circulation

    SciTech Connect

    Duffy, P.B.; Caldeira, K.C.

    1998-02-01

    This final report provides an overview of the goals and accomplishments of this project. Modeling and observational work has raised the possibility that global warming may cause changes in the circulation of the ocean. If such changes would occur they could have important climatic consequences. The first technical goal of this project was to investigate some of these possible changes in ocean circulation in a quantitative way, using a state-of -the-art numerical model of the ocean. Another goal was to develop our ocean model, a detailed three-dimensional numerical model of the ocean circulation and ocean carbon cycles. A major non-technical goal was to establish LLNL as a center of excellence in modelling the ocean circulation and carbon cycle.

  1. Southern Ocean biological impacts on global ocean oxygen

    NASA Astrophysics Data System (ADS)

    Keller, David P.; Kriest, Iris; Koeve, Wolfgang; Oschlies, Andreas

    2016-06-01

    Southern Ocean (SO) physical and biological processes are known to have a large impact on global biogeochemistry. However, the role that SO biology plays in determining ocean oxygen concentrations is not completely understood. These dynamics are investigated here by shutting off SO biology in two marine biogeochemical models. The results suggest that SO biological processes reduce the ocean's oxygen content, mainly in the deep ocean, by 14 to 19%. However, since these processes also trap nutrients that would otherwise be transported northward to fuel productivity and subsequent organic matter export, consumption, and the accompanying oxygen consumption in midlatitude to low-latitude waters, SO biology helps to maintain higher oxygen concentrations in these subsurface waters. Thereby, SO biology can influence the size of the tropical oxygen minimum zones. As a result of ocean circulation the link between SO biological processes and remote oxygen changes operates on decadal to centennial time scales.

  2. Toward Submesocale Ocean Modelling and Observations for Global Ocean Forecast.

    NASA Astrophysics Data System (ADS)

    Drillet, Y.

    2014-12-01

    Mercator Ocean is the French oceanographic operational center involved in the development an operation of global high resolution ocean forecasting systems; it is part of the European Copernicus Marine service initiated during MyOcean project. Mercator Ocean currently delivers daily 1/12° global ocean forecast based on the NEMO model which allows for a good representation of mesoscale structures in main areas of the global ocean. Data assimilation of altimetry provides a precise initialization of the mesoscale structures while in situ observations, mainly based on the ARGO network, and satellite Sea Surface Temperature constrain water mass properties from the surface to intermediate depths. One of the main improvements scheduled in the coming years is the transitioning towards submesoscale permitting horizontal resolution (1/36°). On the basis of numerical simulations in selected areas and standard diagnostics developed to validate operational systems, we will discuss : i) The impact of the resolution increase at the basin scale. ii) Adequacy of numerical schemes, vertical resolution and physical parameterization. iii) Adequacy of currently implemented data assimilation procedures in particular with respect to new high resolution data set such as SWOT.

  3. State of Climate 2011 - Global Ocean Phytoplankton

    NASA Technical Reports Server (NTRS)

    Siegel, D. A.; Antoine, D.; Behrenfeld, M. J.; d'Andon, O. H. Fanton; Fields, E.; Franz, B. A.; Goryl, P.; Maritorena, S.; McClain, C. R.; Wang, M.; Yoder, J. A.

    2012-01-01

    Phytoplankton photosynthesis in the sun lit upper layer of the global ocean is the overwhelmingly dominant source of organic matter that fuels marine ecosystems. Phytoplankton contribute roughly half of the global (land and ocean) net primary production (NPP; gross photosynthesis minus plant respiration) and phytoplankton carbon fixation is the primary conduit through which atmospheric CO2 concentrations interact with the ocean s carbon cycle. Phytoplankton productivity depends on the availability of sunlight, macronutrients (e.g., nitrogen, phosphorous), and micronutrients (e.g., iron), and thus is sensitive to climate-driven changes in the delivery of these resources to the euphotic zone

  4. Improved Global Ocean Color Using Polymer Algorithm

    NASA Astrophysics Data System (ADS)

    Steinmetz, Francois; Ramon, Didier; Deschamps, ierre-Yves; Stum, Jacques

    2010-12-01

    A global ocean color product has been developed based on the use of the POLYMER algorithm to correct atmospheric scattering and sun glint and to process the data to a Level 2 ocean color product. Thanks to the use of this algorithm, the coverage and accuracy of the MERIS ocean color product have been significantly improved when compared to the standard product, therefore increasing its usefulness for global ocean monitor- ing applications like GLOBCOLOUR. We will present the latest developments of the algorithm, its first application to MODIS data and its validation against in-situ data from the MERMAID database. Examples will be shown of global NRT chlorophyll maps produced by CLS with POLYMER for operational applications like fishing or oil and gas industry, as well as its use by Scripps for a NASA study of the Beaufort and Chukchi seas.

  5. Global Education for Ocean County College.

    ERIC Educational Resources Information Center

    Rykiel, Joan Devlin

    This paper presents a rationale for establishing a global education curriculum at Ocean County College (OCC) (New Jersey) and proposes a workable curriculum, along with suggestions for implementation. The author distinguishes between multicultural and global education--both curricula address issues of cultural diversity, human rights, and…

  6. Global Ocean Carbon and Biogeochemistry Coordination

    NASA Astrophysics Data System (ADS)

    Telszewski, Maciej; Tanhua, Toste; Palacz, Artur

    2016-04-01

    The complexity of the marine carbon cycle and its numerous connections to carbon's atmospheric and terrestrial pathways means that a wide range of approaches have to be used in order to establish it's qualitative and quantitative role in the global climate system. Ocean carbon and biogeochemistry research, observations, and modelling are conducted at national, regional, and global levels to quantify the global ocean uptake of atmospheric CO2 and to understand controls of this process, the variability of uptake and vulnerability of carbon fluxes into the ocean. These science activities require support by a sustained, international effort that provides a central communication forum and coordination services to facilitate the compatibility and comparability of results from individual efforts and development of the ocean carbon data products that can be integrated with the terrestrial, atmospheric and human dimensions components of the global carbon cycle. The International Ocean Carbon Coordination Project (IOCCP) was created in 2005 by the IOC of UNESCO and the Scientific Committee on Oceanic Research. IOCCP provides an international, program-independent forum for global coordination of ocean carbon and biogeochemistry observations and integration with global carbon cycle science programs. The IOCCP coordinates an ever-increasing set of observations-related activities in the following domains: underway observations of biogeochemical water properties, ocean interior observations, ship-based time-series observations, large-scale ocean acidification monitoring, inorganic nutrients observations, biogeochemical instruments and autonomous sensors and data and information creation. Our contribution is through the facilitation of the development of globally acceptable strategies, methodologies, practices and standards homogenizing efforts of the research community and scientific advisory groups as well as integrating the ocean biogeochemistry observations with the

  7. DOE Global Energy Storage Database

    DOE Data Explorer

    The DOE International Energy Storage Database has more than 400 documented energy storage projects from 34 countries around the world. The database provides free, up-to-date information on grid-connected energy storage projects and relevant state and federal policies. More than 50 energy storage technologies are represented worldwide, including multiple battery technologies, compressed air energy storage, flywheels, gravel energy storage, hydrogen energy storage, pumped hydroelectric, superconducting magnetic energy storage, and thermal energy storage. The policy section of the database shows 18 federal and state policies addressing grid-connected energy storage, from rules and regulations to tariffs and other financial incentives. It is funded through DOE’s Sandia National Laboratories, and has been operating since January 2012.

  8. Revaluating ocean warming impacts on global phytoplankton

    NASA Astrophysics Data System (ADS)

    Behrenfeld, Michael J.; O'Malley, Robert T.; Boss, Emmanuel S.; Westberry, Toby K.; Graff, Jason R.; Halsey, Kimberly H.; Milligan, Allen J.; Siegel, David A.; Brown, Matthew B.

    2016-03-01

    Global satellite observations document expansions of the low-chlorophyll central ocean gyres and an overall inverse relationship between anomalies in sea surface temperature and phytoplankton chlorophyll concentrations. These findings can provide an invaluable glimpse into potential future ocean changes, but only if the story they tell is accurately interpreted. Chlorophyll is not simply a measure of phytoplankton biomass, but also registers changes in intracellular pigmentation arising from light-driven (photoacclimation) and nutrient-driven physiological responses. Here, we show that the photoacclimation response is an important component of temporal chlorophyll variability across the global ocean. This attribution implies that contemporary relationships between chlorophyll changes and ocean warming are not indicative of proportional changes in productivity, as light-driven decreases in chlorophyll can be associated with constant or even increased photosynthesis. Extension of these results to future change, however, requires further evaluation of how the multifaceted stressors of a warmer, higher-CO2 world will impact plankton communities.

  9. Including eddies in global ocean models

    NASA Astrophysics Data System (ADS)

    Semtner, Albert J.; Chervin, Robert M.

    The ocean 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 ocean that it remains a “final frontier” on the face of the Earth. Many ocean currents are truly global in extent, such as the Antarctic Circumpolar Current and the “conveyor belt” that connects the North Atlantic and North Pacific oceans by flows around the southern 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 ocean 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.

  10. Ocean Observatories and Information: Building a Global Ocean Observing Network

    NASA Astrophysics Data System (ADS)

    Schofield, O.; Glenn, S. M.; Moline, M. A.; Oliver, M.; Irwin, A.; Chao, Y.; Arrott, M.

    Ocean observatories are collections of networks of sensors that are deployed to sample the ocean physics, chemistry, and biology. The goal of these networks is to overcome chronic undersampling of the oceans by providing sustained measurements in space and time. The data collected by these networks are used to address a range of basic and applied research questions, hindered by a lack of data. The ocean observatories represent collections of platforms capable of collecting data over a range of scales. The platforms include ships, satellites, radars, and a range of Lagrangian systems. Data from the individual platforms are aggregated by sophisticated cyberinfrastructure software systems, which when combined with global communications allow for two-way communication between the shoreside personnel and the networks that can be deployed anywhere in the world. This two-way communication allows the networks to be adaptively configured to improve sampling of specific processes. The maturation of these systems comes at a fortuitous time as the oceans are increasingly showing evidence of changes in the physics, chemistry, and biology over the last few decades. Understanding those changes will require the data collected by the ocean observatories.

  11. Ocean plankton. Structure and function of the global ocean microbiome.

    PubMed

    Sunagawa, Shinichi; Coelho, Luis Pedro; Chaffron, Samuel; Kultima, Jens Roat; Labadie, Karine; Salazar, Guillem; Djahanschiri, Bardya; Zeller, Georg; Mende, Daniel R; Alberti, Adriana; Cornejo-Castillo, Francisco M; Costea, Paul I; Cruaud, Corinne; d'Ovidio, Francesco; Engelen, Stefan; Ferrera, Isabel; Gasol, Josep M; Guidi, Lionel; Hildebrand, Falk; Kokoszka, Florian; Lepoivre, Cyrille; Lima-Mendez, Gipsi; Poulain, Julie; Poulos, Bonnie T; Royo-Llonch, Marta; Sarmento, Hugo; Vieira-Silva, Sara; Dimier, Céline; Picheral, Marc; Searson, Sarah; Kandels-Lewis, Stefanie; Bowler, Chris; de Vargas, Colomban; Gorsky, Gabriel; Grimsley, Nigel; Hingamp, Pascal; Iudicone, Daniele; Jaillon, Olivier; Not, Fabrice; Ogata, Hiroyuki; Pesant, Stephane; Speich, Sabrina; Stemmann, Lars; Sullivan, Matthew B; Weissenbach, Jean; Wincker, Patrick; Karsenti, Eric; Raes, Jeroen; Acinas, Silvia G; Bork, Peer

    2015-05-22

    Microbes are dominant drivers of biogeochemical processes, yet drawing a global picture of functional diversity, microbial community structure, and their ecological determinants remains a grand challenge. We analyzed 7.2 terabases of metagenomic data from 243 Tara Oceans samples from 68 locations in epipelagic and mesopelagic waters across the globe to generate an ocean microbial reference gene catalog with >40 million nonredundant, mostly novel sequences from viruses, prokaryotes, and picoeukaryotes. Using 139 prokaryote-enriched samples, containing >35,000 species, we show vertical stratification with epipelagic community composition mostly driven by temperature rather than other environmental factors or geography. We identify ocean microbial core functionality and reveal that >73% of its abundance is shared with the human gut microbiome despite the physicochemical differences between these two ecosystems. PMID:25999513

  12. Achieving Global Ocean Color Climate Data Records

    NASA Technical Reports Server (NTRS)

    Franz, Bryan

    2010-01-01

    Ocean color, or the spectral distribution of visible light upwelling from beneath the ocean surface, carries information on the composition and concentration of biological constituents within the water column. The CZCS mission in 1978 demonstrated that quantitative ocean color measurements could be. made from spaceborne sensors, given sufficient corrections for atmospheric effects and a rigorous calibration and validation program. The launch of SeaWiFS in 1997 represents the beginning of NASA's ongoing efforts to develop a continuous ocean color data record with sufficient coverage and fidelity for global change research. Achievements in establishing and maintaining the consistency of the time-series through multiple missions and varying instrument designs will be highlighted in this talk, including measurements from NASA'S MODIS instruments currently flying on the Terra and Aqua platforms, as well as the MERIS sensor flown by ESA and the OCM-2 sensor recently launched by ISRO.

  13. Sustained growth of the Southern Ocean carbon storage in a warming climate

    NASA Astrophysics Data System (ADS)

    Ito, Takamitsu; Bracco, Annalisa; Deutsch, Curtis; Frenzel, Hartmut; Long, Matthew; Takano, Yohei

    2015-06-01

    We investigate the mechanisms controlling the evolution of Southern Ocean carbon storage under a future climate warming scenario. A subset of Coupled Model Intercomparison Project Phase 5 models predicts that the inventory of biologically sequestered carbon south of 40°S increases about 18-34 Pg C by 2100 relative to the preindustrial condition. Sensitivity experiments with an ocean circulation and biogeochemistry model illustrates the impacts of the wind and buoyancy forcings under a warming climate. Intensified and poleward shifted westerly wind strengthens the upper overturning circulation, not only leading to an increased uptake of anthropogenic CO2 but also releasing biologically regenerated carbon to the atmosphere. Freshening of Antarctic Surface Water causes a slowdown of the lower overturning circulation, leading to an increased Southern Ocean biological carbon storage. The rectified effect of these processes operating together is the sustained growth of the carbon storage in the Southern Ocean, even under the warming climate with a weaker global ocean carbon uptake.

  14. The Global Ocean Observing System: One perspective

    NASA Technical Reports Server (NTRS)

    Wilson, J. Ron

    1992-01-01

    This document presents a possible organization for a Global Ocean Observing System (GOOS) within the Intergovernmental Oceanographic Commission and the joint ocean programs with the World Meteorological Organization. The document and the organization presented here is not intended to be definitive, complete or the best possible organization for such an observation program. It is presented at this time to demonstrate three points. The first point to be made is that an international program office for GOOS along the lines of the WOCE and TOGA IPOs is essential. The second point is that national programs will have to continue to collect data at the scale of WOCE plus TOGA and more. The third point is that there are many existing groups and committees within the IOC and joint IOC/WMO ocean programs that can contribute essential experience to and form part of the basis of a Global Ocean Observing System. It is particularly important to learn from what has worked and what has not worked in the past if a successful ocean observing system is to result.

  15. Carbon Storage in Biologic and Oceanic Reservoirs: Issues and Opportunities

    NASA Astrophysics Data System (ADS)

    Caldeira, K.

    2007-12-01

    Most discussion of carbon capture and storage have focused on geologic reservoirs because these are the reservoirs most likely to provide for long-term storage with a minimum of adverse environmental consequences. Nevertheless, there is interest in storage in other reservoirs such as the biosphere or the oceans. Storage in biological reservoirs such as forests or agricultural soils may in many cases be relatively inexpensive. Because this biological storage involves carbon dioxide removal from the atmosphere, it can potentially offset emissions from the transportation sector. Biological storage can be politically popular because it can be deployed with simple technologies, can be deployed in developing countries, and in many cases involves other environmental co-benefits. However, total capacity is limited. Furthermore, biological storage is temporary unless the store is actively maintained forever. Such temporary storage can be valuable, although it is clearly not as valuable as the quasi-permanent storage offered by good geologic storage reservoirs Ocean storage options fall into two main classes. The first involves conventional separation and compression of carbon dioxide from large point sources which would then be piped into the deep ocean and released either into the water or as a lake on the sea floor. In either case, the carbon dioxide would eventually interact with the atmosphere and contribute to ocean acidification. However, there is potential for the development of long-term engineered containment of carbon dioxide on or in the sea floor. The second main ocean storage option involves increasing ocean alkalinity, probably by dissolving carbonate minerals. This approach may offer safe, quasi- permanent, and cost-effective storage in settings where coastal carbon dioxide point sources are co-located with carbonate mineral deposits. Not every location or carbon dioxide source is suitable for geologic storage of carbon dioxide. At this early stage, it is

  16. Robust warming of the global upper ocean.

    PubMed

    Lyman, John M; Good, Simon A; Gouretski, Viktor V; Ishii, Masayoshi; Johnson, Gregory C; Palmer, Matthew D; Smith, Doug M; Willis, Josh K

    2010-05-20

    A large ( approximately 10(23) J) multi-decadal globally averaged warming signal in the upper 300 m of the world's oceans was reported roughly a decade ago and is attributed to warming associated with anthropogenic greenhouse gases. The majority of the Earth's total energy uptake during recent decades has occurred in the upper ocean, but the underlying uncertainties in ocean warming are unclear, limiting our ability to assess closure of sea-level budgets, the global radiation imbalance and climate models. For example, several teams have recently produced different multi-year estimates of the annually averaged global integral of upper-ocean heat content anomalies (hereafter OHCA curves) or, equivalently, the thermosteric sea-level rise. Patterns of interannual variability, in particular, differ among methods. Here we examine several sources of uncertainty that contribute to differences among OHCA curves from 1993 to 2008, focusing on the difficulties of correcting biases in expendable bathythermograph (XBT) data. XBT data constitute the majority of the in situ measurements of upper-ocean heat content from 1967 to 2002, and we find that the uncertainty due to choice of XBT bias correction dominates among-method variability in OHCA curves during our 1993-2008 study period. Accounting for multiple sources of uncertainty, a composite of several OHCA curves using different XBT bias corrections still yields a statistically significant linear warming trend for 1993-2008 of 0.64 W m(-2) (calculated for the Earth's entire surface area), with a 90-per-cent confidence interval of 0.53-0.75 W m(-2). PMID:20485432

  17. Global charts of ocean tide loading effects

    SciTech Connect

    Francis, O.; Mazzega, P. )

    1990-07-15

    Global ocean tide loading charts of the radial displacement, the potential divided by g (gravity acceleration), and the gravity effect have been computed using the 11 constituents M{sub 2}, S{sub 2}, N{sub 2}, K{sub 2}K{sub 1}, O{sub 1}, P{sub 1}, Q{sub 1}, M{sub f}, M{sub m}, S{sub s a} of Schwiderski's tidal model. These new charts have a resolution of 1{degree}{times}1{degree} on the continents as well as on the oceanic area. A description of Farrell's convolution method to compute the loading effects is given, and an estimate of the numerical errors leads to the conclusion that these global charts have a precision better than 2.5% independent of the accuracy of Schwiderski's maps. The current approximation of the loading effects by a proportionality relation with the local oceanic tides is also compared with Farrell's convolution method. Departures of several centimeters systematically appear, in particular over the continental shelves. The authors then show that the maps of the oceanic tides deduced from satellite altimetry could be corrected for the loading effect by an iterative computational procedure based on their algorithm of Farrell's convolution.

  18. Ocean Properties in 2007 Described by the Mercator-Ocean Global Ocean Analysis and Forecasting System

    NASA Astrophysics Data System (ADS)

    Drevillon, M.; Lellouche, J.; Greiner, E.; Verbrugge, N.; Remy, E.; Crosnier, L.

    2008-12-01

    Since the beginning of GODAE and also in the framework of the European projects MERSEA and now GMES/MyOcean, Mercator-Ocean has been designing a hierarchy of operational oceanography analysis and forecasting systems. These systems are based on numerical models of the ocean and data assimilation systems which interpolate in an optimal way all available observations of the ocean. The real time operation of these systems began in 2001, in order to produce each week realistic 3-dimensional oceanic conditions (temperature, salinity, currents) two weeks back in time and a two weeks forecast, driven at the surface by atmospheric conditions from the European Center for Medium Range Weather Forecast (ECMWF). Since April 2008, the state-of-the-art Mercator Ocean forecasting system demonstrates that the use of the ocean and sea ice model NEMO and of the data assimilation system SAM2 (Système d'Assimilation Mercator V2) can produce high quality real time analyses and forecast of the ocean at the global scale, and up to the "eddy resolving" horizontal resolution. This system currently comprises a global ocean configuration at 1/4° horizontal resolution and a North Atlantic and Mediterranean zoom at 1/12°, both having 50 levels on the vertical with a surface refinement. Both have been run and comprehensively validated over the year 2007. The realism of the description of the ocean physics, sea ice, water masses, and volume transports is assessed. Although some biases develop in regions where complex interactions take place between the different limitations of the system (mostly the Antarctic and the tropics), the results show a "qualitative jump" of the physical and statistical skills of the system. They reinforce the scientific feasibility of the future upgrade of the system into a global high resolution configuration at 1/12°.

  19. Global equivalent magnetization of the oceanic lithosphere

    NASA Astrophysics Data System (ADS)

    Dyment, J.; Choi, Y.; Hamoudi, M.; Lesur, V.; Thebault, E.

    2015-11-01

    As a by-product of the construction of a new World Digital Magnetic Anomaly Map over oceanic areas, we use an original approach based on the global forward modeling of seafloor spreading magnetic anomalies and their comparison to the available marine magnetic data to derive the first map of the equivalent magnetization over the World's ocean. This map reveals consistent patterns related to the age of the oceanic lithosphere, the spreading rate at which it was formed, and the presence of mantle thermal anomalies which affects seafloor spreading and the resulting lithosphere. As for the age, the equivalent magnetization decreases significantly during the first 10-15 Myr after its formation, probably due to the alteration of crustal magnetic minerals under pervasive hydrothermal alteration, then increases regularly between 20 and 70 Ma, reflecting variations in the field strength or source effects such as the acquisition of a secondary magnetization. As for the spreading rate, the equivalent magnetization is twice as strong in areas formed at fast rate than in those formed at slow rate, with a threshold at ∼40 km/Myr, in agreement with an independent global analysis of the amplitude of Anomaly 25. This result, combined with those from the study of the anomalous skewness of marine magnetic anomalies, allows building a unified model for the magnetic structure of normal oceanic lithosphere as a function of spreading rate. Finally, specific areas affected by thermal mantle anomalies at the time of their formation exhibit peculiar equivalent magnetization signatures, such as the cold Australian-Antarctic Discordance, marked by a lower magnetization, and several hotspots, marked by a high magnetization.

  20. Is low frequency ocean sound increasing globally?

    PubMed

    Miksis-Olds, Jennifer L; Nichols, Stephen M

    2016-01-01

    Low frequency sound has increased in the Northeast Pacific Ocean over the past 60 yr [Ross (1993) Acoust. Bull. 18, 5-8; (2005) IEEE J. Ocean. Eng. 30, 257-261; Andrew, Howe, Mercer, and Dzieciuch (2002) J. Acoust. Soc. Am. 129, 642-651; McDonald, Hildebrand, and Wiggins (2006) J. Acoust. Soc. Am. 120, 711-717; Chapman and Price (2011) J. Acoust. Soc. Am. 129, EL161-EL165] and in the Indian Ocean over the past decade, [Miksis-Olds, Bradley, and Niu (2013) J. Acoust. Soc. Am. 134, 3464-3475]. More recently, Andrew, Howe, and Mercer's [(2011) J. Acoust. Soc. Am. 129, 642-651] observations in the Northeast Pacific show a level or slightly decreasing trend in low frequency noise. It remains unclear what the low frequency trends are in other regions of the world. In this work, data from the Comprehensive Nuclear-Test Ban Treaty Organization International Monitoring System was used to examine the rate and magnitude of change in low frequency sound (5-115 Hz) over the past decade in the South Atlantic and Equatorial Pacific Oceans. The dominant source observed in the South Atlantic was seismic air gun signals, while shipping and biologic sources contributed more to the acoustic environment at the Equatorial Pacific location. Sound levels over the past 5-6 yr in the Equatorial Pacific have decreased. Decreases were also observed in the ambient sound floor in the South Atlantic Ocean. Based on these observations, it does not appear that low frequency sound levels are increasing globally. PMID:26827043

  1. Coccolithophorid blooms in the global ocean

    NASA Technical Reports Server (NTRS)

    Brown, Christopher W.; Yoder, James A.

    1994-01-01

    The global distribution pattern of coccolithophrid blooms was mapped in order to ascertain the prevalence of these blooms in the world's oceans and to estimate their worldwide production of CaCO3 and dimethyl sulfide (DMS). Mapping was accomplished by classifying pixels of 5-day global composites of coastal zone color scanner imagery into bloom and nonbloom classes using a supervised, multispectral classification scheme. Surface waters with the spectral signature of coccolithophorid blooms annually covered an average of 1.4 x 10(exp 6) sq km in the world oceans from 1979 to 1985, with the subpolar latitudes accounting for 71% of this surface area. Classified blooms were most extensive in the Subartic North Atlantic. Large expanses of the bloom signal were also detected in the North Pacific, on the Argentine shelf and slope, and in numerous lower latitude marginal seas and shelf regions. The greatest spatial extent of classified blooms in subpolar oceanic regions occurred in the months from summer to early autumn, while those in lower latitude marginal seas occurred in midwinter to early spring. Though the classification scheme was effcient in separating bloom and nonbloom classes during test simulations, and biogeographical literature generally confirms the resulting distribution pattern of blooms in the subpolar regions, the cause of the bloom signal is equivocal in some geographic areas, particularly on shelf regions at lower latitudes. Standing stock estimates suggest that the presumed Emiliania huxleyi blooms act as a significant source of calcite carbon and DMS sulfur on a regional scale. On a global scale, however, the satellite-detected coccolithophorid blooms are estimated to play only a minor role in the annual production of these two compounds and their flux from the surface mixed layer.

  2. Ecological controls over global soil carbon storage

    SciTech Connect

    Schimel, D.S.

    1995-09-01

    Globally, soil carbon comprises about 2/3 of terrestrial carbon storage. Soil carbon is thus an important reservoir of carbon, but also influences the responses of ecosystems to change by controlling many aspects of nutrient cycling. While broad-scale patterns of soil carbon accumulation can be explained in terms of climatic and biome distributions, many ecological processes also influence the storage and turnover of carbon in soils. I will present a synthesis of information from field studies, model experiments and global data bases on factors controlling the turnover and storage of soil carbon. First, I will review a series of studies showing links between vegetation change (successional and invasions) and soil carbon. Then I will review model analyses of the sensitivity of soil carbon to climatic and ecological changes. Results show that soil carbon storage is broadly sensitive to climate but greatly influenced by the allocation of detritus between resistant (lignaceous and woody) and more labile forms, and that biotic changes that affect allocation, affect soil carbon substantially at regionally and perhaps global scales.

  3. The Global S$_1$ Ocean Tide

    NASA Technical Reports Server (NTRS)

    Ray, Richard D.; Egbert, G. D.

    2003-01-01

    The small S$_1$ ocean tide is caused primarily by diurnal atmospheric pressure loading. Its excitation is therefore unlike any other diurnal tide. The global character of $S-1$ is here determined by numerical modeling and by analysis of Topex/Poseidon satellite altimeter data. The two approaches yield reasonably consistent results, and large ( $ greater than $l\\cm) amplitudes in several regions are further confirmed by comparison with coastal tide gauges. Notwithstanding their excitation differences, S$-1$ and other diurnal tides are found to share several common features, such as relatively large amplitudes in the Arabian Sea, the Sea of Okhotsk, and the Gulf of Alaska. The most noticeable difference is the lack of an S$-1$ Antarctic Kelvin wave. These similarities and differences can be explained in terms of the coherences between near-diurnal oceanic normal modes and the underlying tidal forcings. While gravitational diurnal tidal forces excite primarily a 28-hour Antarctic-Pacific mode, the S$_1$ air tide excites several other near-diurnal modes, none of which has large amplitudes near Antarctica.

  4. Picophytoplankton biomass distribution in the global ocean

    NASA Astrophysics Data System (ADS)

    Buitenhuis, E. T.; Li, W. K. W.; Vaulot, D.; Lomas, M. W.; Landry, M. R.; Partensky, F.; Karl, D. M.; Ulloa, O.; Campbell, L.; Jacquet, S.; Lantoine, F.; Chavez, F.; Macias, D.; Gosselin, M.; McManus, G. B.

    2012-08-01

    The smallest marine phytoplankton, collectively termed picophytoplankton, have been routinely enumerated by flow cytometry since the late 1980s during cruises throughout most of the world ocean. We compiled a database of 40 946 data points, with separate abundance entries for Prochlorococcus, Synechococcus and picoeukaryotes. We use average conversion factors for each of the three groups to convert the abundance data to carbon biomass. After gridding with 1° spacing, the database covers 2.4% of the ocean surface area, with the best data coverage in the North Atlantic, the South Pacific and North Indian basins, and at least some data in all other basins. The average picophytoplankton biomass is 12 ± 22 μg C l-1 or 1.9 g C m-2. We estimate a total global picophytoplankton biomass of 0.53-1.32 Pg C (17-39% Prochlorococcus, 12-15% Synechococcus and 49-69% picoeukaryotes), with an intermediate/best estimate of 0.74 Pg C. Future efforts in this area of research should focus on reporting calibrated cell size and collecting data in undersampled regions. http://doi.pangaea.de/10.1594/PANGAEA.777385

  5. Picophytoplankton biomass distribution in the global ocean

    NASA Astrophysics Data System (ADS)

    Buitenhuis, E. T.; Li, W. K. W.; Vaulot, D.; Lomas, M. W.; Landry, M.; Partensky, F.; Karl, D. M.; Ulloa, O.; Campbell, L.; Jacquet, S.; Lantoine, F.; Chavez, F.; Macias, D.; Gosselin, M.; McManus, G. B.

    2012-04-01

    The smallest marine phytoplankton, collectively termed picophytoplankton, have been routinely enumerated by flow cytometry since the late 1980s, during cruises throughout most of the world ocean. We compiled a database of 40 946 data points, with separate abundance entries for Prochlorococcus, Synechococcus and picoeukaryotes. We use average conversion factors for each of the three groups to convert the abundance data to carbon biomass. After gridding with 1° spacing, the database covers 2.4% of the ocean surface area, with the best data coverage in the North Atlantic, the South Pacific and North Indian basins. The average picophytoplankton biomass is 12 ± 22 μg C l-1 or 1.9 g C m-2. We estimate a total global picophytoplankton biomass of 0.53-0.74 Pg C (17-39% Prochlorococcus, 12-15% Synechococcus and 49-69% picoeukaryotes). Future efforts in this area of research should focus on reporting calibrated cell size, and collecting data in undersampled regions.

  6. Global View of the Arctic Ocean

    NASA Technical Reports Server (NTRS)

    2000-01-01

    together to create a time-lapsed view of this remote and inhospitable region. So far, they have processed one season's worth of images.

    'We can see large cracks in the ice cover, where most ice grows, ' said Kwok. 'These cracks are much longer than previously thought, some as long as 2,000 kilometers (1,200 miles),' Kwok continued. 'If the ice is thinning due to warming, we'll expect to see more of these long cracks over the Arctic Ocean. '

    Scientists believe this is one of the most significant breakthroughs in the last two decades of ice research. 'We are now in a position to better understand the sea ice cover and the role of the Arctic Ocean in global climate change, ' said Kwok.

    Radar can see through clouds and any kind of weather system, day or night, and as the Arctic regions are usually cloud-covered and subject to long, dark winters, radar is proving to be extremely useful. However, compiling these data into extremely detailed pictures of the Arctic is a challenging task.

    'This is truly a major innovation in terms of the quantities of data being processed and the novelty of the methods being used, ' said Verne Kaupp, director of the Alaska SAR Facility at the University of Alaska, Fairbanks.

    The mission is a joint project between JPL, the Alaska SAR Facility, and the Canadian Space Agency. Launched by NASA in 1995, the Radarsat satellite is operated by the Canadian Space Agency. JPL manages the Sea Ice Thickness Derived From High Resolution Radar Imagery project for NASA's Earth Science Enterprise, Washington, DC. The Earth Science Enterprise is dedicated to studying how natural and human-induced changes affect our global environment.

  7. Fifteen years of ocean observations with the global Argo array

    NASA Astrophysics Data System (ADS)

    Riser, Stephen C.; Freeland, Howard J.; Roemmich, Dean; Wijffels, Susan; Troisi, Ariel; Belbéoch, Mathieu; Gilbert, Denis; Xu, Jianping; Pouliquen, Sylvie; Thresher, Ann; Le Traon, Pierre-Yves; Maze, Guillaume; Klein, Birgit; Ravichandran, M.; Grant, Fiona; Poulain, Pierre-Marie; Suga, Toshio; Lim, Byunghwan; Sterl, Andreas; Sutton, Philip; Mork, Kjell-Arne; Vélez-Belchí, Pedro Joaquín; Ansorge, Isabelle; King, Brian; Turton, Jon; Baringer, Molly; Jayne, Steven R.

    2016-02-01

    More than 90% of the heat energy accumulation in the climate system between 1971 and the present has been in the ocean. Thus, the ocean plays a crucial role in determining the climate of the planet. Observing the oceans is problematic even under the most favourable of conditions. Historically, shipboard ocean sampling has left vast expanses, particularly in the Southern Ocean, unobserved for long periods of time. Within the past 15 years, with the advent of the global Argo array of profiling floats, it has become possible to sample the upper 2,000 m of the ocean globally and uniformly in space and time. The primary goal of Argo is to create a systematic global network of profiling floats that can be integrated with other elements of the Global Ocean Observing System. The network provides freely available temperature and salinity data from the upper 2,000 m of the ocean with global coverage. The data are available within 24 hours of collection for use in a broad range of applications that focus on examining climate-relevant variability on seasonal to decadal timescales, multidecadal climate change, improved initialization of coupled ocean-atmosphere climate models and constraining ocean analysis and forecasting systems.

  8. Modeling Nitrogen Isotopes in the Global Ocean

    NASA Astrophysics Data System (ADS)

    Somes, C.; Schmittner, A.

    2008-12-01

    The nitrogen isotopic signal measured in marine sediments has the potential to be a valuable paleoceanographic proxy. It captures the response of different biological processes in the marine ecosystem including photosynthesis, nitrogen fixation, denitrification as well as processes within the food chain. A simple marine ecosystem model that includes the interactive cycling of nitrogen, phosphorus, and oxygen is augmented to record nitrogen isotopes in the University of Victoria Earth System Climate Model. New nitrogen isotopic tracers are employed at all trophic levels of the ecosystem. This includes the δ15N of nitrate, both classes of phytoplankton (nitrogen fixers and all other phytoplankton), zooplankton, and detritus. Despite a few shortcomings, it is shown that the nitrogen isotope model can capture the major trends observed in the modern climate. The ability to model nitrogen isotopes in a global coupled ocean- atmosphere-sea ice-ecosystem model gives us a unique opportunity to directly infer what physical and biological changes in the climate system are driving the δ15N signal on spatial and temporal scales. This is a valuable tool giving us tremendous insight on how to interpret the nitrogen isotopic signal.

  9. Consistency of the current global ocean observing systems from an Argo perspective

    NASA Astrophysics Data System (ADS)

    von Schuckmann, K.; Sallée, J.-B.; Chambers, D.; Le Traon, P.-Y.; Cabanes, C.; Gaillard, F.; Speich, S.; Hamon, M.

    2014-06-01

    Variations in the world's ocean heat storage and its associated volume changes are a key factor to gauge global warming and to assess the earth's energy and sea level budget. Estimating global ocean heat content (GOHC) and global steric sea level (GSSL) with temperature/salinity data from the Argo network reveals a positive change of 0.5 ± 0.1 W m-2 (applied to the surface area of the ocean) and 0.5 ± 0.1 mm year-1 during the years 2005 to 2012, averaged between 60° S and 60° N and the 10-1500 m depth layer. In this study, we present an intercomparison of three global ocean observing systems: the Argo network, satellite gravimetry from GRACE and satellite altimetry. Their consistency is investigated from an Argo perspective at global and regional scales during the period 2005-2010. Although we can close the recent global ocean sea level budget within uncertainties, sampling inconsistencies need to be corrected for an accurate global budget due to systematic biases in GOHC and GSSL in the Tropical Ocean. Our findings show that the area around the Tropical Asian Archipelago (TAA) is important to closing the global sea level budget on interannual to decadal timescales, pointing out that the steric estimate from Argo is biased low, as the current mapping methods are insufficient to recover the steric signal in the TAA region. Both the large regional variability and the uncertainties in the current observing system prevent us from extracting indirect information regarding deep-ocean changes. This emphasizes the importance of continuing sustained effort in measuring the deep ocean from ship platforms and by beginning a much needed automated deep-Argo network.

  10. Distinctive climate signals in reanalysis of global ocean heat content

    NASA Astrophysics Data System (ADS)

    Balmaseda, Magdalena A.; Trenberth, Kevin E.; KäLléN, Erland

    2013-05-01

    The elusive nature of the post-2004 upper ocean warming has exposed uncertainties in the ocean's role in the Earth's energy budget and transient climate sensitivity. Here we present the time evolution of the global ocean heat content for 1958 through 2009 from a new observation-based reanalysis of the ocean. Volcanic eruptions and El Niño events are identified as sharp cooling events punctuating a long-term ocean warming trend, while heating continues during the recent upper-ocean-warming hiatus, but the heat is absorbed in the deeper ocean. In the last decade, about 30% of the warming has occurred below 700 m, contributing significantly to an acceleration of the warming trend. The warming below 700 m remains even when the Argo observing system is withdrawn although the trends are reduced. Sensitivity experiments illustrate that surface wind variability is largely responsible for the changing ocean heat vertical distribution.

  11. Absolute geostrophic currents in global tropical oceans

    NASA Astrophysics Data System (ADS)

    Yang, Lina; Yuan, Dongliang

    2016-03-01

    A set of absolute geostrophic current (AGC) data for the period January 2004 to December 2012 are calculated using the P-vector method based on monthly gridded Argo profiles in the world tropical oceans. The AGCs agree well with altimeter geostrophic currents, Ocean Surface Current Analysis-Real time currents, and moored current-meter measurements at 10-m depth, based on which the classical Sverdrup circulation theory is evaluated. Calculations have shown that errors of wind stress calculation, AGC transport, and depth ranges of vertical integration cannot explain non-Sverdrup transport, which is mainly in the subtropical western ocean basins and equatorial currents near the Equator in each ocean basin (except the North Indian Ocean, where the circulation is dominated by monsoons). The identified non-Sverdrup transport is thereby robust and attributed to the joint effect of baroclinicity and relief of the bottom (JEBAR) and mesoscale eddy nonlinearity.

  12. Global Observations in Ocean and Cryosphere

    NASA Astrophysics Data System (ADS)

    Rhein, Monika; Chambers, Don; Johnson, Gregory; Rintoul, Steve; Comiso, Joey; Vaughan, David

    2014-05-01

    Changes from direct and proxy observations in all components of the climate system are assessed In "Climate Change 2013: The Physical Science Basis", the Working Group I contribution to the Fifth IPCC report. This talk addresses the main climate-related changes observed in ocean and the cryosphere, as well as their roles in the climate system. The ocean has absorbed more than 90% of the energy increase in the climate system in the last 40 years, with warming detected even in the abyss over the last few decades. The ocean has also taken up about 30% of the carbon released by fossil fuel burning and land use change since 1750, lowering the pH of (acidifying) near-surface waters. Relatively saline near-surface ocean waters, where evaporation dominates, have become more saline, and relatively fresh regions, where precipitation dominates, have become fresher; providing indirect evidence of change in evaporation and precipitation over the oceans. Arctic Sea Ice extent has decreased much more than Antarctic sea ice extent has increased from 1979 through 2012. Ice sheets and glaciers have been losing mass at an increasing rate over recent decades. Sea level rise is driven by both, ocean warming and mass loss from ice sheets and glaciers into the ocean. The observational estimates of the various contributors to the total sea level rise account for the total from 1993-2010.

  13. Atmospheric and oceanographic research review, 1978. [global weather, ocean/air interactions, and climate

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Research activities related to global weather, ocean/air interactions, and climate are reported. The global weather research is aimed at improving the assimilation of satellite-derived data in weather forecast models, developing analysis/forecast models that can more fully utilize satellite data, and developing new measures of forecast skill to properly assess the impact of satellite data on weather forecasting. The oceanographic research goal is to understand and model the processes that determine the general circulation of the oceans, focusing on those processes that affect sea surface temperature and oceanic heat storage, which are the oceanographic variables with the greatest influence on climate. The climate research objective is to support the development and effective utilization of space-acquired data systems in climate forecast models and to conduct sensitivity studies to determine the affect of lower boundary conditions on climate and predictability studies to determine which global climate features can be modeled either deterministically or statistically.

  14. Changes in ocean vertical heat transport with global warming

    NASA Astrophysics Data System (ADS)

    Zika, Jan D.; Laliberté, Frédéric; Mudryk, Lawrence R.; Sijp, Willem P.; Nurser, A. J. G.

    2015-06-01

    Heat transport between the surface and deep ocean strongly influences transient climate change. Mechanisms setting this transport are investigated using coupled climate models and by projecting ocean circulation into the temperature-depth diagram. In this diagram, a "cold cell" cools the deep ocean through the downwelling of Antarctic waters and upwelling of warmer waters and is balanced by warming due to a "warm cell," coincident with the interhemispheric overturning and previously linked to wind and haline forcing. With anthropogenic warming, the cold cell collapses while the warm cell continues to warm the deep ocean. Simulations with increasingly strong warm cells, set by their mean Southern Hemisphere winds, exhibit increasing deep-ocean warming in response to the same anthropogenic forcing. It is argued that the partition between components of the circulation which cool and warm the deep ocean in the preindustrial climate is a key determinant of ocean vertical heat transport with global warming.

  15. Recent variability of the global ocean carbon sink

    NASA Astrophysics Data System (ADS)

    Landschützer, P.; Gruber, N.; Bakker, D. C. E.; Schuster, U.

    2014-09-01

    We present a new observation-based estimate of the global oceanic carbon dioxide (CO2) sink and its temporal variation on a monthly basis from 1998 through 2011 and at a spatial resolution of 1°×1°. This sink estimate rests upon a neural network-based mapping of global surface ocean observations of the partial pressure of CO2 (pCO2) from the Surface Ocean CO2 Atlas database. The resulting pCO2 has small biases when evaluated against independent observations in the different ocean basins, but larger randomly distributed differences exist particularly in high latitudes. The seasonal climatology of our neural network-based product agrees overall well with the Takahashi et al. (2009) climatology, although our product produces a stronger seasonal cycle at high latitudes. From our global pCO2 product, we compute a mean net global ocean (excluding the Arctic Ocean and coastal regions) CO2 uptake flux of -1.42 ± 0.53 Pg C yr-1, which is in good agreement with ocean inversion-based estimates. Our data indicate a moderate level of interannual variability in the ocean carbon sink (±0.12 Pg C yr-1, 1σ) from 1998 through 2011, mostly originating from the equatorial Pacific Ocean, and associated with the El Niño-Southern Oscillation. Accounting for steady state riverine and Arctic Ocean carbon fluxes our estimate further implies a mean anthropogenic CO2 uptake of -1.99 ± 0.59 Pg C yr-1 over the analysis period. From this estimate plus the most recent estimates for fossil fuel emissions and atmospheric CO2 accumulation, we infer a mean global land sink of -2.82 ± 0.85 Pg C yr-1 over the 1998 through 2011 period with strong interannual variation.

  16. Global Earth Response to Loading by Ocean Tide Models

    NASA Technical Reports Server (NTRS)

    Estes, R. H.; Strayer, J. M.

    1979-01-01

    Mathematical and programming techniques to numerically calculate Earth response to global semidiurnal and diurnal ocean tide models were developed. Global vertical crustal deformations were evaluated for M sub 2, S sub 2, N sub 2, K sub 2, K sub 1, O sub 1, and P sub 1 ocean tide loading, while horizontal deformations were evaluated for the M sub 2 tidal load. Tidal gravity calculations were performed for M sub 2 tidal loads, and strain tensor elements were evaluated for M sub 2 loads. The M sub 2 solution used for the ocean tide included the effects of self-gravitation and crustal loading.

  17. GLobal Ocean Data Analysis Project (GLODAP): Data and Analyses

    DOE Data Explorer

    Sabine, C. L.; Key, R. M.; Feely, R. A.; Bullister, J. L.; Millero, F. J.; Wanninkhof, R.; Peng, T. H.; Kozyr, A.

    The GLobal Ocean Data Analysis Project (GLODAP) is a cooperative effort to coordinate global synthesis projects funded through NOAA, DOE, and NSF as part of the Joint Global Ocean Flux Study - Synthesis and Modeling Project (JGOFS-SMP). Cruises conducted as part of the World Ocean Circulation Experiment (WOCE), JGOFS, and the NOAA Ocean-Atmosphere Exchange Study (OACES) over the decade of the 1990s have created an important oceanographic database for the scientific community investigating carbon cycling in the oceans. The unified data help to determine the global distributions of both natural and anthropogenic inorganic carbon, including radiocarbon. These estimates provide an important benchmark against which future observational studies will be compared. They also provide tools for the direct evaluation of numerical ocean carbon models. GLODAP information available through CDIAC includes gridded and bottle data, a live server, an interactive atlas that provides access to data plots, and other tools for viewing and interacting with the data. [from http://cdiac.esd.ornl.gov/oceans/glodap/Glopintrod.htm](Specialized Interface)

  18. Global survey of CO{sub 2} in the oceans

    SciTech Connect

    1996-12-31

    Since 1990, the US Department of Energy has supported a Global Survey of CO{sub 2} in the Oceans. This project arose from a long history of DOE-supported research into the fate of the energy-related pollutant CO{sub 2}, including its fate in the oceans. The survey is a key component of the international JGOFS (Joint Global Ocean Flux Study) and is closely associated with the international WOCE (World Ocean Circulation Experiment). In the course of this project, the Science Team that oversees the project has established close links with investigators involved in NOAA`s complementary Ocean Atmosphere Carbon Exchange Study (OACES) as well as with numerous international investigators.

  19. The role of clouds and oceans in global greenhouse warming

    SciTech Connect

    Hoffert, M.I.

    1992-12-01

    During the past three years we have conducted several studies using models and a combination of satellite data, in situ meteorological and oceanic data, and paleoclimate reconstructions, under the DoE program, Quantifying the Link Between Change in Radiative Balance and Atmospheric Temperature''. Our goals were to investigate effects of global cloudiness variations on global climate and their implications for cloud feedback and continue development and application of NYU transient climate/ocean models, with emphasis on coupled effects of greenhouse warming and feedbacks by both the clouds and oceans. Our original research plan emphasized the use of cloud, surface temperature and ocean data sets interpreted by focused climate/ocean models to develop a cloud radiative forcing scenario for the past 100 years and to assess the transient climate response; to narrow key uncertainties in the system; and to identify those aspects of the climate system most likely to be affected by greenhouse warming over short, medium and long time scales.

  20. Global observations of ocean Rossby waves

    SciTech Connect

    Chelton, D.B.; Schlax, M.G.

    1996-04-12

    Rossby waves play a critical role in the transient adjustment of ocean circulation to changes in large-scale atmospheric forcing. The TOPEX/POSEIDON satellite altimeter has detected Rossby waves throughout much of the world ocean from sea level signals with {approx_lt} 10-centimeters amplitude and {approx_lt} 500-kilometer wavelength. Outside of the tropics Rossby waves are abruptly amplified by major topographic features. Analysis of 3 years of data reveals discrepancies between observed and theoretical Rossby wave phase speeds that indicate that the standard theory for free, linear Rossby waves in an incomplete description of the observed waves. 32 refs., 5 figs.

  1. Global coupled sea ice-ocean state estimation

    NASA Astrophysics Data System (ADS)

    Fenty, Ian; Menemenlis, Dimitris; Zhang, Hong

    2015-09-01

    We study the impact of synthesizing ocean and sea ice concentration data with a global, eddying coupled sea ice-ocean configuration of the Massachusetts Institute of Technology general circulation model with the goal of reproducing the 2004 three-dimensional time-evolving ice-ocean state. This work builds on the state estimation framework developed in the Estimating the Circulation and Climate of the Ocean consortium by seeking a reconstruction of the global sea ice-ocean system that is simultaneously consistent with (1) a suite of in situ and remotely-sensed ocean and ice data and (2) the physics encoded in the numerical model. This dual consistency is successfully achieved here by adjusting only the model's initial hydrographic state and its atmospheric boundary conditions such that misfits between the model and data are minimized in a least-squares sense. We show that synthesizing both ocean and sea ice concentration data is required for the model to adequately reproduce the observed details of the sea ice annual cycle in both hemispheres. Surprisingly, only modest adjustments to our first-guess atmospheric state and ocean initial conditions are necessary to achieve model-data consistency, suggesting that atmospheric reanalysis products remain a leading source of errors for sea ice-ocean model hindcasts and reanalyses. The synthesis of sea ice data is found to ameliorate misfits in the high latitude ocean, especially with respect to upper ocean stratification, temperature, and salinity. Constraining the model to sea ice concentration modestly reduces ICESat-derived Arctic ice thickness errors by improving the temporal and spatial evolution of seasonal ice. Further increases in the accuracy of global sea ice thickness in the model likely require the direct synthesis of sea ice thickness data.

  2. Sharing Data in the Global Ocean Observing System (Invited)

    NASA Astrophysics Data System (ADS)

    Lindstrom, E. J.; McCurdy, A.; Young, J.; Fischer, A. S.

    2010-12-01

    We examine the evolution of data sharing in the field of physical oceanography to highlight the challenges now before us. Synoptic global observation of the ocean from space and in situ platforms has significantly matured over the last two decades. In the early 1990’s the community data sharing challenges facing the World Ocean Circulation Experiment (WOCE) largely focused on the behavior of individual scientists. Satellite data sharing depended on the policy of individual agencies. Global data sets were delivered with considerable delay and with enormous personal sacrifice. In the 2000’s the requirements for global data sets and sustained observations from the likes of the U.N. Framework Convention on Climate Change have led to data sharing and cooperation at a grander level. It is more effective and certainly more efficient. The Joint WMO/IOC Technical Commission on Oceanography and Marine Meteorology (JCOMM) provided the means to organize many aspects of data collection and data dissemination globally, for the common good. In response the Committee on Earth Observing Satellites organized Virtual Constellations to enable the assembly and sharing of like kinds of satellite data (e.g., sea surface topography, ocean vector winds, and ocean color). Individuals in physical oceanography have largely adapted to the new rigors of sharing data for the common good, and as a result of this revolution new science has been enabled. Primary obstacles to sharing have shifted from the individual level to the national level. As we enter into the 2010’s the demands for ocean data continue to evolve with an expanded requirement for more real-time reporting and broader disciplinary coverage, to answer key scientific and societal questions. We are also seeing the development of more numerous national contributions to the global observing system. The drivers for the establishment of global ocean observing systems are expanding beyond climate to include biological and

  3. Decoupling of Iron and Phosphate in the Global Ocean

    NASA Technical Reports Server (NTRS)

    Parekh, Payal

    2003-01-01

    Iron is an essential micronutrient for marine phytoplankton, limiting their growth in high nutrient, low chlorophyll regions of the ocean. I use a hierarchy of ocean circulation and biogeochemistry models to understand controls on global iron distribution. I formulate a mechanistic model of iron cycling which includes scavenging onto sinking particles and complexation with an organic ligand. The iron cycle is coupled to a phosphorus cycling model. Iron's aeolian source is prescribed. In the context of a highly idealized multi-box model scheme, the model can be brought into consistency with the relatively sparse ocean observations of iron in the oceans. This biogeochemical scheme is also implemented in a coarse resolution ocean general circulation model. This model also successfully reproduces the broad regional patterns of iron and phosphorus. In particular, the high macronutrient concentrations of the Southern Ocean result from iron limitation in the model. Due to the potential ability of iron to change the efficiency of the carbon pump in the remote Southern Ocean, I study Southern Ocean surface phosphate response to increased aeolian dust flux. My box model and GCM results suggest that a global ten fold increase in dust flux can support a phosphate drawdown of 0.25-0.5 micromolar.

  4. Global Climate Change and Ocean Education

    NASA Astrophysics Data System (ADS)

    Spitzer, W.; Anderson, J.

    2011-12-01

    The New England Aquarium, collaborating with other aquariums across the country, is leading a national effort to enable aquariums and related informal science education institutions to effectively communicate the impacts of climate change and ocean acidification on marine animals, habitats and ecosystems. Our goal is to build on visitors' emotional connection with ocean animals, connect to their deeply held values, help them understand causes and effects of climate change and motivate them to embrace effective solutions. Our objectives are to: (1) Build a national coalition of aquariums and related informal education institutions collaborating on climate change education; (2) Develop an interpretive framework for climate change and the ocean that is scientifically sound, research-based, field tested and evaluated; and (3) Build capacity of aquariums to interpret climate change via training for interpreters, interactive exhibits and activities and communities of practice for ongoing support. Centers of informal learning have the potential to bring important environmental issues to the public by presenting the facts, explaining the science, connecting with existing values and interests, and motivating concern and action. Centers that work with live animals (including aquariums, zoos, nature centers, national parks, national marine sanctuaries, etc.) are unique in that they attract large numbers of people of all ages (over 140 million in the US), have strong connections to the natural, and engage many visitors who may not come with a primary interest in science. Recent research indicates that that the public expects and trusts aquariums, zoos, and museums to communicate solutions to environmental and ocean issues, and to advance ocean conservation, and that climate change is the environmental issue of most concern to the public; Ironically, however, most people do not associate climate change with ocean health, or understand the critical role that the ocean plays in

  5. Tides of global ice-covered oceans

    NASA Astrophysics Data System (ADS)

    Wunsch, Carl

    2016-08-01

    The tides of an ice-covered ocean are examined using a Cartesian representation of the elastic and fluid equations. Although unconstrained by any observations, the ocean tides of a Neoproterozoic "snowball" Earth could have been significantly larger than they are today. Time-mean tidal-residual circulations would then have been set up that are competitive with the circulation driven by geothermal heating. In any realistic configuration, the snowball Earth would have had an ice cover that is in the thin shell limit, but by permitting the ice thickness to become large, more interesting ice tidal response can be found, ones conceivably of application to bodies in the outer Solar System or hypothetical exoplanets. Little can be said concerning a reduction in tidal dissipation necessary to avoid a crisis in the history of the lunar orbit.

  6. Oceans Abound? Tectonic Tests of Global Ocean Models for Enceladus and Mimas

    NASA Astrophysics Data System (ADS)

    Rhoden, A.; Henning, W. G.; Bland, M. T.; Tajeddine, R.; Hurford, T., Jr.

    2015-12-01

    Librations identified in Cassinidata imply that Mimas either has a global ocean or an irregular core (Tajeddine et al., 2014). A global ocean is the only model consistent with Enceladus' librations (Tajeddine et al., 2015). A global ocean can also explain gravity measurements of Enceladus as long as the overlying ice shell is thicker in the north pole than the south pole (McKinnon, 2015), although a regional sea is also possible (Iess et al., 2014). Generations of fractures at Enceladus' south pole may indicate longitudinal migration of the ice shell, which would also require a global ocean (Patthoff and Kattenhorn, 2011). Because both Mimas and Enceladus have eccentric orbits (0.0196 and 0.0047, respectively) interior models that include oceans can generate much larger tidal stresses than models without oceans. However, the enhancement in tidal stress due to oceans creates complications for both moons. Mimas' surface is ancient and heavily cratered; only about 40 tectonic features have been identified, globally (Schenk, 2011). The lack of tidal-tectonic activity on Mimas implies that either it has not experienced large tidal stresses over its surface age or that its ice shell behaves quite differently than Europa. Enceladus has a young, heavily-fractured region at the south pole, and an old, heavily-cratered region at the north pole. Are global ocean models compatible with ongoing, tidal-tectonic activity at Enceladus' south pole and the lack of activity on Mimas and at Enceladus' north pole? We consider whether global oceans are compatible with the geologic records of Mimas and Enceladus by calculating tidal stresses for 5-layer interior structure models. To explore the range of possible interior structures, we vary the ice shell thickness, the depth of the upper brittle ice layer, and the viscosities of the brittle and ductile ice layers. We find that a global ocean within Mimas generates tidal stresses comparable to those on Europa (~100 kPa) and in some cases

  7. PHC: A Global Ocean Hydrography with a High-Quality Arctic Ocean.

    NASA Astrophysics Data System (ADS)

    Steele, Michael; Morley, Rebecca; Ermold, Wendy

    2001-05-01

    A new gridded ocean climatology, the Polar Science Center Hydrographic Climatology (PHC), has been created that merges the 1998 version of the World Ocean Atlas with the new regional Arctic Ocean Atlas. The result is a global climatology for temperature and salinity that contains a good description of the Arctic Ocean and its environs. Monthly, seasonal, and annual average products have been generated. How the original datasets were prepared for merging, how the optimal interpolation procedure was performed, and characteristics of the resulting dataset are discussed, followed by a summary and discussion of future plans.

  8. Arctic Ocean basin liquid freshwater storage trend 1992-2012

    NASA Astrophysics Data System (ADS)

    Rabe, B.; Karcher, M.; Kauker, F.; Schauer, U.; Toole, J. M.; Krishfield, R. A.; Pisarev, S.; Kikuchi, T.; Su, J.

    2014-02-01

    Freshwater in the Arctic Ocean plays an important role in the regional ocean circulation, sea ice, and global climate. From salinity observed by a variety of platforms, we are able, for the first time, to estimate a statistically reliable liquid freshwater trend from monthly gridded fields over all upper Arctic Ocean basins. From 1992 to 2012 this trend was 600±300 km3 yr-1. A numerical model agrees very well with the observed freshwater changes. A decrease in salinity made up about two thirds of the freshwater trend and a thickening of the upper layer up to one third. The Arctic Ocean Oscillation index, a measure for the regional wind stress curl, correlated well with our freshwater time series. No clear relation to Arctic Oscillation or Arctic Dipole indices could be found. Following other observational studies, an increased Bering Strait freshwater import to the Arctic Ocean, a decreased Davis Strait export, and enhanced net sea ice melt could have played an important role in the freshwater trend we observed.

  9. Influence of the Southern Ocean on the Global deep ocean stratification

    NASA Astrophysics Data System (ADS)

    Sun, S.; Eisenman, I.; Stewart, A.

    2015-12-01

    The stratification of the deep ocean plays a key role in the climate system by influencing the ocean circulation and regulating the outgassing of CO2. Previous studies have suggested that Southern Ocean processes control the global ocean stratification below the main thermocline (i.e., below ~500m). In this study, three ocean-only simulations are carried out with the Community Earth System Model (CESM1): one control simulation forced with Pre-industrial (PI) surface conditions, a second control simulation forced with Last Glacial Maximum (LGM) surface conditions, and a test simulation forced with LGM surface conditions in southern high latitudes and PI surface conditions elsewhere. We find that the test simulation does broadly reproduce the LGM density stratification of the global ocean below 2000m, but not at intermediate depths between 500m and 1500m. We propose a mechanism whereby the stratification of the intermediate-depth waters is influenced by the differing effects on the surface buoyancy distribution of fixed versus restoring aspects of the surface buoyancy forcing. This implies the Southern Ocean exerts less influence over the global deep ocean stratification than has been previously suggested, at least when considering the difference between LGM and PI climates in CESM1.

  10. Monitoring changes in upper ocean heat storage from satellites

    NASA Technical Reports Server (NTRS)

    Miller, J. R.

    1978-01-01

    A one-dimensional model of the upper ocean mixed-layer was developed to determine how the parameters which can be measured from satellites affect the development of the layer. The results show that the form of the dissipation term is important in achieving cyclic annual states, that the layer deepending rate depends on the averaging period for the surface heat flux and wind stress, that wind direction, as well as magnitude, can affect the deepening rate and that horizontal advective effects cannot simply be superimposed on the model results. An algorithm is given which uses satellite derived wind stress and sea surface temperature data to predict real time changes in upper ocean heat storage during the cooling seasons.

  11. Sources of global warming of the upper ocean on decadal period scales

    USGS Publications Warehouse

    White, Warren B.; Dettinger, M.D.; Cayan, D.R.

    2003-01-01

    Recent studies find global climate variability in the upper ocean and lower atmosphere during the twentieth century dominated by quasi-biennial, interannual, quasi-decadal and interdecadal signals. The quasi-decadal signal in upper ocean temperature undergoes global warming/cooling of ???0.1??C, similar to that occuring with the interannual signal (i.e., El Nin??o-Southern Oscillation), both signals dominated by global warming/cooling in the tropics. From the National Centers for Environmental Prediction troposphere reanalysis and Scripps Institution of Oceanography upper ocean temperature reanalysis we examine the quasi-decadal global tropical diabetic heat storage (DHS) budget from 1975 to 2000. We find the anomalous DHS warming tendency of 0.3-0.9 W m-2 driven principally by a downward global tropical latent-plus-sensible heat flux anomaly into the ocean, overwhelming the tendency by weaker upward shortwave-minus-longwave heat flux anomaly to drive an anomalous DHS cooling tendency. During the peak quasi-decadal warming the estimated dissipation of DHS anomaly of 0.2-0.5 W m-2 into the deep ocean and a similar loss to the overlying atmosphere through air-sea heat flux anomaly are balanced by a decrease in the net poleward Ekman heat advection out of the tropics of 0.4-0.7 W m-2. This scenario is nearly the opposite of that accounting for global tropical warming during the El Nin??o. These diagnostics confirm that even though the global quasi-decadal signal is phase-locked to the 11-year signal in the Sun's surface radiative forcing of ???0.1 W m-2, the anomalous global tropical DHS tendency cannot be driven by it directly.

  12. A fully-implicit model of the global ocean circulation

    NASA Astrophysics Data System (ADS)

    Weijer, Wilbert; Dijkstra, Henk A.; Öksüzoğlu, Hakan; Wubs, Fred W.; de Niet, Arie C.

    2003-12-01

    With the recent developments in the solution methods for large-dimensional nonlinear algebraic systems, fully-implicit ocean circulation models are now becoming feasible. In this paper, the formulation of such a three-dimensional global ocean model is presented. With this implicit model, the sensitivity of steady states to parameters can be investigated efficiently using continuation methods. In addition, the implicit formulation allows for much larger time steps than can be used with explicit models. To demonstrate current capabilities of the implicit global ocean model, we use a relatively low-resolution (4° horizontally and 12 levels vertically) version. For this configuration, we present: (i) an explicit calculation of the bifurcation diagram associated with hysteresis behavior of the ocean circulation and (ii) the scaling behavior of the Atlantic meridional overturning versus the magnitude of the vertical mixing coefficient of heat and salt.

  13. Ocean Global Warming Impacts on the South America Climate

    NASA Astrophysics Data System (ADS)

    Ramos-Da-Silva, Renato

    2016-03-01

    The global Ocean-Land-Atmosphere Model (OLAM) model was used to estimate the impacts of the global oceanic warming on the climate projections for the 21st Century focusing on the South America region. This new model is able to represent simultaneously the global and regional scales using a refining grid approach for the region of interest. First, the model was run for a 31-year control period consisting on the years 1960-1990 using the monthly Sea Surface Temperature (SST) from the Atmospheric Model Intercomparison Project (AMIP) data as a driver for the ocean fluxes. Then, the model was run for the period 2010-2100 using the monthly projected SST from the Hadley Center model (HadCM3) as a driver for the oceanic changes. The model was set up with an icosahedral triangular global grid having about 250 km of grid spacing and with a refining grid resolution with the cells reaching about 32 km over the South America region. The results show an overall temperature increase mainly over the center of the Amazon basin caused by the increase of the greenhouse effect of the water vapor; a decrease on precipitation mainly over the northeast Brazil and an increase in the south and over the western Amazon region; and a major increase on the near surface wind speed. These results are similar to the global coupled models; however, OLAM has a novel type of grid that can provide the interaction between the global and regional scales simultaneously.

  14. Marine defaunation: animal loss in the global ocean.

    PubMed

    McCauley, Douglas J; Pinsky, Malin L; Palumbi, Stephen R; Estes, James A; Joyce, Francis H; Warner, Robert R

    2015-01-16

    Marine defaunation, or human-caused animal loss in the oceans, emerged forcefully only hundreds of years ago, whereas terrestrial defaunation has been occurring far longer. Though humans have caused few global marine extinctions, we have profoundly affected marine wildlife, altering the functioning and provisioning of services in every ocean. Current ocean trends, coupled with terrestrial defaunation lessons, suggest that marine defaunation rates will rapidly intensify as human use of the oceans industrializes. Though protected areas are a powerful tool to harness ocean productivity, especially when designed with future climate in mind, additional management strategies will be required. Overall, habitat degradation is likely to intensify as a major driver of marine wildlife loss. Proactive intervention can avert a marine defaunation disaster of the magnitude observed on land. PMID:25593191

  15. A Global Ocean State Estimate at the Last Glacial Maximum

    NASA Astrophysics Data System (ADS)

    Amrhein, D. E.; Wunsch, C. I.

    2015-12-01

    Many features of Earth's climate at the Last Glacial Maximum (LGM, ca. 20,000 years ago) remain a mystery, including the role of the ocean circulation in transporting thermal energy, salinity, and other tracers. Most efforts at reconstructing the ocean state during the LGM have relied either upon integrations of general circulation models under prescribed LGM boundary conditions or the interpretation of climate proxy records without explicit physical constraints. Here we describe a global, primitive equation simulation of the LGM ocean with boundary conditions (wind, surface air temperature, and other atmospheric variables) and mixing parameters derived by a least-squares fit of an ocean general circulation model to observations of deep ocean stable isotopes and sea surface temperatures at the LGM.

  16. The timescales of global surface-ocean connectivity

    NASA Astrophysics Data System (ADS)

    Jönsson, Bror F.; Watson, James R.

    2016-04-01

    Planktonic communities are shaped through a balance of local evolutionary adaptation and ecological succession driven in large part by migration. The timescales over which these processes operate are still largely unresolved. Here we use Lagrangian particle tracking and network theory to quantify the timescale over which surface currents connect different regions of the global ocean. We find that the fastest path between two patches--each randomly located anywhere in the surface ocean--is, on average, less than a decade. These results suggest that marine planktonic communities may keep pace with climate change--increasing temperatures, ocean acidification and changes in stratification over decadal timescales--through the advection of resilient types.

  17. Global ocean modeling on the Connection Machine

    SciTech Connect

    Smith, R.D.; Dukowicz, J.K.; Malone, R.C.

    1993-10-01

    The authors have developed a version of the Bryan-Cox-Semtner ocean model (Bryan, 1969; Semtner, 1976; Cox, 1984) for massively parallel computers. Such models are three-dimensional, Eulerian models that use latitude and longitude as the horizontal spherical coordinates and fixed depth levels as the vertical coordinate. The incompressible Navier-Stokes equations, with a turbulent eddy viscosity, and mass continuity equation are solved, subject to the hydrostatic and Boussinesq approximations. The traditional model formulation uses a rigid-lid approximation (vertical velocity = 0 at the ocean surface) to eliminate fast surface waves. These waves would otherwise require that a very short time step be used in numerical simulations, which would greatly increase the computational cost. To solve the equations with the rigid-lid assumption, the equations of motion are split into two parts: a set of twodimensional ``barotropic`` equations describing the vertically-averaged flow, and a set of three-dimensional ``baroclinic`` equations describing temperature, salinity and deviations of the horizontal velocities from the vertically-averaged flow.

  18. Anisotropy of eddy variability in the global ocean

    NASA Astrophysics Data System (ADS)

    Stewart, K. D.; Spence, P.; Waterman, S.; Sommer, J. Le; Molines, J.-M.; Lilly, J. M.; England, M. H.

    2015-11-01

    The anisotropy of eddy variability in the global ocean is examined in geostrophic surface velocities derived from satellite observations and in the horizontal velocities of a 1/12° global ocean model. Eddy anisotropy is of oceanographic interest as it is through anisotropic velocity fluctuations that the eddy and mean-flow fields interact dynamically. This study is timely because improved observational estimates of eddy anisotropy will soon be available with Surface Water and Ocean Topography (SWOT) altimetry data. We find there to be good agreement between the characteristics and distributions of eddy anisotropy from the present satellite observations and model ocean surface. In the model, eddy anisotropy is found to have significant vertical structure and is largest close to the ocean bottom, where the anisotropy aligns with the underlying isobaths. The highly anisotropic bottom signal is almost entirely contained in the barotropic variability. Upper-ocean variability is predominantly baroclinic and the alignment is less sensitive to the underlying bathymetry. These findings offer guidance for introducing a parameterization of eddy feedbacks, based on the eddy kinetic energy and underlying bathymetry, to operate on the barotropic flow and better account for the effects of barotropic Reynolds stresses unresolved in coarse-resolution ocean models.

  19. Global ocean monitoring for the World Climate Research Programme.

    PubMed

    Revelle, R; Bretherton, F

    1986-07-01

    Oceanic research and modelling for the World Climate Research Program will utilize several recently-developed instruments and measuring techniques as well as well-tested, long-used instruments. Ocean-scanning satellites will map the component of the ocean-surface topography related to ocean currents and mesoscale eddies and to fluctuating water volumes caused by ocean warming and cooling. Other satellite instruments will measure the direction and magnitude of wind stress on the sea surface, surface water temperatures, the distribution of chlorophyll and other photosynthetic pigments, the characteristics of internal waves, and possible precipitation over the ocean. Networks of acoustic transponders will obtain a three-dimensional picture of the distribution of temperature from the surface down to mid-depth and of long-term changes in temperature at depth. Ocean research vessels will determine the distribution and fate of geochemical tracers and will also make high-precision, deep hydrographic casts. Ships of opportunity, using expendable instruments, will measure temperature, salinity and currents in the upper water layers. Drifting and anchored buoys will also measure these properties as well as those of the air above the sea surface. Tide gauges installed on islands and exposed coastal locations will measure variations in monthly and shorter-period mean sea level. These tide gauges will provide 'ground truth' for the satellite maps of sea-surface topography, and will also determine variations in ocean currents and temperature.All these instruments will be used in several major programs, the most ambitious of which is the World Ocean Circulation Experiment (WOCE) designed to obtain global measurements of major currents throughout the world ocean, greater understanding of the transformation of water masses, and the role of advective, convective, and turbulent processes in exchange of properties between surface and deep-ocean layers.A five- to ten-year experiment

  20. The positive Indian Ocean Dipole-like response in the tropical Indian Ocean to global warming

    NASA Astrophysics Data System (ADS)

    Luo, Yiyong; Lu, Jian; Liu, Fukai; Wan, Xiuquan

    2016-04-01

    Climate models project a positive Indian Ocean Dipole (pIOD)-like SST response in the tropical Indian Ocean to global warming. By employing the Community Earth System Model and applying an overriding technique to its ocean component (version 2 of the Parallel Ocean Program), this study investigates the similarities and differences of the formation mechanisms for the changes in the tropical Indian Ocean during the pIOD versus global warming. Results show that their formation processes and related seasonality are quite similar; in particular, wind-thermocline-SST feedback is the leading mechanism in producing the anomalous cooling over the eastern tropics in both cases. Some differences are also found, including the fact that the cooling effect of the vertical advection over the eastern tropical Indian Ocean is dominated by the anomalous vertical velocity during the pIOD but by the anomalous upper-ocean stratification under global warming. These findings are further examined through an analysis of the mixed layer heat budget.

  1. A global ocean reanalysis product in the China Ocean Reanalysis (CORA) project

    NASA Astrophysics Data System (ADS)

    Han, Guijun; Fu, Hongli; Zhang, Xuefeng; Li, Wei; Wu, Xinrong; Wang, Xidong; Zhang, Lianxin

    2013-11-01

    The first version of a global ocean reanalysis over multiple decades (1979-2008) has been completed by the National Marine Data and Information Service within the China Ocean Reanalysis (CORA) project. The global ocean model employed is based upon the ocean general circulation model of the Massachusetts Institute of Technology. A sequential data assimilation scheme within the framework of 3D variational (3DVar) analysis, called multi-grid 3DVar, is implemented in 3D space for retrieving multiple-scale observational information. Assimilated oceanic observations include sea level anomalies (SLAs) from multi-altimeters, sea surface temperatures (SSTs) from remote sensing satellites, and in-situ temperature/salinity profiles. Evaluation showed that compared to the model simulation, the annual mean heat content of the global reanalysis is significantly approaching that of World Ocean Atlas 2009 (WOA09) data. The quality of the global temperature climatology was found to be comparable with the product of Simple Ocean Data Assimilation (SODA), and the major ENSO events were reconstructed. The global and Atlantic meridional overturning circulations showed some similarity as SODA, although significant differences were found to exist. The analysis of temperature and salinity in the current version has relatively larger errors at high latitudes and improvements are ongoing in an updated version. CORA was found to provide a simulation of the subsurface current in the equatorial Pacific with a correlation coefficient beyond about 0.6 compared with the Tropical Atmosphere Ocean (TAO) mooring data. The mean difference of SLAs between altimetry data and CORA was less than 0.1 m in most years.

  2. Ocean Margins Program: Closure on the global carbon cycle. Program description

    SciTech Connect

    Riches, M.R.

    1994-08-01

    The Department of Energy`s Ocean Margins Program (OMP) is designed to quantitatively assess the importance of coastal ocean systems in the global carbon cycle. Since the beginning of the Industrial Revolution, human energy-related activities have dramatically altered the global carbon cycle, and consequently, this cycle is not presently in a steady-state. To reduce major uncertainties in predicting future global environmental quality, it is imperative to understand the sources and sinks of atmospheric CO{sub 2}, the role of anthropogenic activities in disrupting the natural carbon cycle, and the effects of, and feedbacks between, these activities and the natural carbon cycle. Due to continuously increased loading of nutrients to the margins, which, globally, is related to the rate of human population growth and high population densities in coastal states, biological carbon fixation has been stimulated. Depending on the fate of the fixed carbon, this stimulation has the potential to mitigate the anthropogenically derived Co{sub 2}. Determining the factors that control the magnitude of carbon exchanges between the ocean margins and the atmosphere, and the subsequent fate of this carbon, is crucial to predicting the strength and capacity of the oceans to absorb excess anthropogenic atmospheric CO{sub 2}. The goals of the OMP are to: quantify the ecological and biogeochemical processes and mechanisms that define the cycling, flux, and storage of carbon and other biogenic elements at the land/ocean interface; identify how ocean-margin sources and sinks of carbon change in response to human activities; and determine whether continental shelves are quantitatively significant in removing atmospheric carbon dioxide and isolating it via burial in sediments or export to the interior of the open ocean.

  3. Decadal Changes in Global Ocean Annual Primary Production

    NASA Technical Reports Server (NTRS)

    Gregg, Watson; Conkright, Margarita E.; Behrenfeld, Michael J.; Ginoux, Paul; Casey, Nancy W.; Koblinsky, Chester J. (Technical Monitor)

    2002-01-01

    The Sea-viewing Wide Field-of-View Sensor (SeaWiFS) has produced the first multi-year time series of global ocean chlorophyll observations since the demise of the Coastal Zone Color Scanner (CZCS) in 1986. Global observations from 1997-present from SeaWiFS combined with observations from 1979-1986 from the CZCS should in principle provide an opportunity to observe decadal changes in global ocean annual primary production, since chlorophyll is the primary driver for estimates of primary production. However, incompatibilities between algorithms have so far precluded quantitative analysis. We have developed and applied compatible processing methods for the CZCS, using modern advances in atmospheric correction and consistent bio-optical algorithms to advance the CZCS archive to comparable quality with SeaWiFS. We applied blending methodologies, where in situ data observations are incorporated into the CZCS and SeaWiFS data records, to provide improvement of the residuals. These re-analyzed, blended data records provide maximum compatibility and permit, for the first time, a quantitative analysis of the changes in global ocean primary production in the early-to-mid 1980's and the present, using synoptic satellite observations. An intercomparison of the global and regional primary production from these blended satellite observations is important to understand global climate change and the effects on ocean biota. Photosynthesis by chlorophyll-containing phytoplankton is responsible for biotic uptake of carbon in the oceans and potentially ultimately from the atmosphere. Global ocean annual primary decreased from the CZCS record to SeaWiFS, by nearly 6% from the early 1980s to the present. Annual primary production in the high latitudes was responsible for most of the decadal change. Conversely, primary production in the low latitudes generally increased, with the exception of the tropical Pacific. The differences and similarities of the two data records provide evidence

  4. Perfluoroalkylated substances in the global tropical and subtropical surface oceans.

    PubMed

    González-Gaya, Belén; Dachs, Jordi; Roscales, Jose L; Caballero, Gemma; Jiménez, Begoña

    2014-11-18

    In this study, perfluoroalkylated substances (PFASs) were analyzed in 92 surface seawater samples taken during the Malaspina 2010 expedition which covered all the tropical and subtropical Atlantic, Pacific and Indian oceans. Nine ionic PFASs including C6-C10 perfluoroalkyl carboxylic acids (PFCAs), C4 and C6-C8 perfluoroalkyl sulfonic acids (PFSAs) and two neutral precursors perfluoroalkyl sulfonamides (PFASAs), were identified and quantified. The Atlantic Ocean presented the broader range in concentrations of total PFASs (131-10900 pg/L, median 645 pg/L, n = 45) compared to the other oceanic basins, probably due to a better spatial coverage. Total concentrations in the Pacific ranged from 344 to 2500 pg/L (median = 527 pg/L, n = 27) and in the Indian Ocean from 176 to 1976 pg/L (median = 329, n = 18). Perfluorooctanesulfonic acid (PFOS) was the most abundant compound, accounting for 33% of the total PFASs globally, followed by perfluorodecanoic acid (PFDA, 22%) and perfluorohexanoic acid (PFHxA, 12%), being the rest of the individual congeners under 10% of total PFASs, even for perfluorooctane carboxylic acid (PFOA, 6%). PFASAs accounted for less than 1% of the total PFASs concentration. This study reports the ubiquitous occurrence of PFCAs, PFSAs, and PFASAs in the global ocean, being the first attempt, to our knowledge, to show a comprehensive assessment in surface water samples collected in a single oceanic expedition covering tropical and subtropical oceans. The potential factors affecting their distribution patterns were assessed including the distance to coastal regions, oceanic subtropical gyres, currents and biogeochemical processes. Field evidence of biogeochemical controls on the occurrence of PFASs was tentatively assessed considering environmental variables (solar radiation, temperature, chlorophyll a concentrations among others), and these showed significant correlations with some PFASs, but explaining small to moderate percentages of variability

  5. Potential increasing dominance of heterotrophy in the global ocean

    NASA Astrophysics Data System (ADS)

    Kvale, K. F.; Meissner, K. J.; Keller, D. P.

    2015-07-01

    Autotrophy is largely resource-limited in the modern ocean. Paleo evidence indicates this was not necessarily the case in warmer climates, and modern observations as well as standard metabolic theory suggest continued ocean warming could shift global ecology towards heterotrophy, thereby reducing autotrophic nutrient limitation. Such a shift would entail strong nutrient recycling in the upper ocean and high rates of net primary production (NPP), yet low carbon export to the deep ocean and sediments. We demonstrate transition towards such a state in the early 22nd century as a response to business-as-usual representative concentration pathway forcing (RCP8.5) in an intermediate complexity Earth system model in three configurations; with and without an explicit calcifier phytoplankton class and calcite ballast model. In all models nutrient regeneration in the near-surface becomes an increasingly important driver of primary production. The near-linear relationship between changes in NPP and global sea surface temperature (SST) found over the 21st century becomes exponential above a 2-4{ }\\circ {{C}} global mean SST change. This transition to a more heterotrophic ocean agrees roughly with metabolic theory.

  6. Global ocean conveyor lowers extinction risk in the deep sea

    NASA Astrophysics Data System (ADS)

    Henry, Lea-Anne; Frank, Norbert; Hebbeln, Dierk; Wienberg, Claudia; Robinson, Laura; van de Flierdt, Tina; Dahl, Mikael; Douarin, Mélanie; Morrison, Cheryl L.; López Correa, Matthias; Rogers, Alex D.; Ruckelshausen, Mario; Roberts, J. Murray

    2014-06-01

    General paradigms of species extinction risk are urgently needed as global habitat loss and rapid climate change threaten Earth with what could be its sixth mass extinction. Using the stony coral Lophelia pertusa as a model organism with the potential for wide larval dispersal, we investigated how the global ocean conveyor drove an unprecedented post-glacial range expansion in Earth's largest biome, the deep sea. We compiled a unique ocean-scale dataset of published radiocarbon and uranium-series dates of fossil corals, the sedimentary protactinium-thorium record of Atlantic meridional overturning circulation (AMOC) strength, authigenic neodymium and lead isotopic ratios of circulation pathways, and coral biogeography, and integrated new Bayesian estimates of historic gene flow. Our compilation shows how the export of Southern Ocean and Mediterranean waters after the Younger Dryas 11.6 kyr ago simultaneously triggered two dispersal events in the western and eastern Atlantic respectively. Each pathway injected larvae from refugia into ocean currents powered by a re-invigorated AMOC that led to the fastest postglacial range expansion ever recorded, covering 7500 km in under 400 years. In addition to its role in modulating global climate, our study illuminates how the ocean conveyor creates broad geographic ranges that lower extinction risk in the deep sea.

  7. An operational global ocean forecast system and its applications

    NASA Astrophysics Data System (ADS)

    Mehra, A.; Tolman, H. L.; Rivin, I.; Rajan, B.; Spindler, T.; Garraffo, Z. D.; Kim, H.

    2012-12-01

    A global Real-Time Ocean Forecast System (RTOFS) was implemented in operations at NCEP/NWS/NOAA on 10/25/2011. This system is based on an eddy resolving 1/12 degree global HYCOM (HYbrid Coordinates Ocean Model) and is part of a larger national backbone capability of ocean modeling at NWS in strong partnership with US Navy. The forecast system is run once a day and produces a 6 day long forecast using the daily initialization fields produced at NAVOCEANO using NCODA (Navy Coupled Ocean Data Assimilation), a 3D multi-variate data assimilation methodology. As configured within RTOFS, HYCOM has a horizontal equatorial resolution of 0.08 degrees or ~9 km. The HYCOM grid is on a Mercator projection from 78.64 S to 47 N and north of this it employs an Arctic dipole patch where the poles are shifted over land to avoid a singularity at the North Pole. This gives a mid-latitude (polar) horizontal resolution of approximately 7 km (3.5 km). The coastline is fixed at 10 m isobath with open Bering Straits. This version employs 32 hybrid vertical coordinate surfaces with potential density referenced to 2000 m. Vertical coordinates can be isopycnals, often best for resolving deep water masses, levels of equal pressure (fixed depths), best for the well mixed unstratified upper ocean and sigma-levels (terrain-following), often the best choice in shallow water. The dynamic ocean model is coupled to a thermodynamic energy loan ice model and uses a non-slab mixed layer formulation. The forecast system is forced with 3-hourly momentum, radiation and precipitation fluxes from the operational Global Forecast System (GFS) fields. Results include global sea surface height and three dimensional fields of temperature, salinity, density and velocity fields used for validation and evaluation against available observations. Several downstream applications of this forecast system will also be discussed which include search and rescue operations at US Coast Guard, navigation safety information

  8. Sources of global warming in upper ocean temperature during El Niño

    USGS Publications Warehouse

    White, Warren B.; Cayan, Daniel R.; Dettinger, Mike; Auad, Guillermo

    2001-01-01

    Global average sea surface temperature (SST) from 40°S to 60°N fluctuates ±0.3°C on interannual period scales, with global warming (cooling) during El Niño (La Niña). About 90% of the global warming during El Niño occurs in the tropical global ocean from 20°S to 20°N, half because of large SST anomalies in the tropical Pacific associated with El Niño and the other half because of warm SST anomalies occurring over ∼80% of the tropical global ocean. From examination of National Centers for Environmental Prediction [Kalnay et al., 1996] and Comprehensive Ocean-Atmosphere Data Set [Woodruff et al., 1993] reanalyses, tropical global warming during El Niño is associated with higher troposphere moisture content and cloud cover, with reduced trade wind intensity occurring during the onset phase of El Niño. During this onset phase the tropical global average diabatic heat storage tendency in the layer above the main pycnocline is 1–3 W m−2above normal. Its principal source is a reduction in the poleward Ekman heat flux out of the tropical ocean of 2–5 W m−2. Subsequently, peak tropical global warming during El Niño is dissipated by an increase in the flux of latent heat to the troposphere of 2–5 W m−2, with reduced shortwave and longwave radiative fluxes in response to increased cloud cover tending to cancel each other. In the extratropical global ocean the reduction in poleward Ekman heat flux out of the tropics during the onset of El Niño tends to be balanced by reduction in the flux of latent heat to the troposphere. Thus global warming and cooling during Earth's internal mode of interannual climate variability arise from fluctuations in the global hydrological balance, not the global radiation balance. Since it occurs in the absence of extraterrestrial and anthropogenic forcing, global warming on decadal, interdecadal, and centennial period scales may also occur in association with Earth's internal modes of climate variability on those scales.

  9. GLOBAL ENVIRONMENTAL CHANGE ISSUES IN THE WESTERN INDIAN OCEAN REGION

    EPA Science Inventory

    Mounting evidence from both instrumental and proxy records shows global climate continues to change. nalysis of near-surface temperatures over land and oceans during the past 130 years shows marked warming during the first half of this century with relatively steady temperatures ...

  10. Oceanic biogeochemical controls on global dynamics of persistent organic pollutants.

    PubMed

    Dachs, Jordi; Lohmann, Rainer; Ockenden, Wendy A; Méjanelle, Laurence; Eisenreich, Steven J; Jones, Kevin C

    2002-10-15

    Understanding and quantifying the global dynamics and sinks of persistent organic pollutants (POPs) is important to assess their environmental impact and fate. Air-surface exchange processes, where temperature plays a central role in controlling volatilization and deposition, are of key importance in controlling global POP dynamics. The present study is an assessment of the role of oceanic biogeochemical processes, notably phytoplankton uptake and vertical fluxes of particles, on the global dynamics of POPs. Field measurements of atmospheric polychlorinated biphenyls (PCBs), polychlorinated dibenzodioxins (PCDDs), and furans (PCDFs) are combined with remote sensing estimations of oceanic temperature, wind speed, and chlorophyll, to model the interactions between air-water exchange, phytoplankton uptake, and export of organic matter and POPs out of the mixed surface ocean layer. Deposition is enhanced in the mid-high latitudes and is driven by sinking marine particulate matter, rather than by a cold condensation effect. However, the relative contribution of the biological pump is a function of the physical-chemical properties of POPs. It is concluded that oceanic biogeochemical processes play a critical role in controlling the global dynamics and the ultimate sink of POPs. PMID:12387392

  11. Evaluating the deep-ocean circulation of a global ocean model using carbon isotopic ratios

    NASA Astrophysics Data System (ADS)

    Paul, André; Dutkiewicz, Stephanie; Gebbie, Jake; Losch, Martin; Marchal, Olivier

    2016-04-01

    We study the sensitivity of a global three-dimensional biotic ocean carbon-cycle model to the parameterizations of gas exchange and biological productivity as well as to deep-ocean circulation strength, and we employ the carbon isotopic ratios δ13C and Δ14C of dissolved inorganic carbon for a systematic evaluation against observations. Radiocarbon (Δ14C) in particular offers the means to assess the model skill on a time scale of 100 to 1000 years relevant to the deep-ocean circulation. The carbon isotope ratios are included as tracers in the MIT general circulation model (MITgcm). The implementation involves the fractionation processes during photosynthesis and air-sea gas exchange. We present the results of sixteen simulations combining two different parameterizations of the piston velocity, two different parameterizations of biological productivity (including the effect of iron fertilization) and four different overturning rates. These simulations were first spun up to equilibrium (more than 10,000 years of model simulation) and then continued from AD 1765 to AD 2002. For the model evaluation, we followed the OCMIP-2 (Ocean Carbon-Cycle Model Intercomparision Project phase two) protocol, comparing the results to GEOSECS (Geochemical Ocean Sections Survey) and WOCE (World Ocean Circulation Experiment) δ13C and natural Δ14C data in the world ocean. The range of deep natural Δ14C (below 1000 m) for our single model (MITgcm) was smaller than for the group of different OCMIP-2 models. Furthermore, differences between different model parameterizations were smaller than for different overturning rates. We conclude that carbon isotope ratios are a useful tool to evaluate the deep-ocean circulation. Since they are also available from deep-sea sediment records, we postulate that the simulation of carbon isotope ratios in a global ocean model will aid in estimating the deep-ocean circulation and climate during present and past.

  12. Patterns and Emerging Trends in Global Ocean Health

    PubMed Central

    Halpern, Benjamin S.; Longo, Catherine; Lowndes, Julia S. Stewart; Best, Benjamin D.; Frazier, Melanie; Katona, Steven K.; Kleisner, Kristin M.; Rosenberg, Andrew A.; Scarborough, Courtney; Selig, Elizabeth R.

    2015-01-01

    International and regional policies aimed at managing ocean ecosystem health need quantitative and comprehensive indices to synthesize information from a variety of sources, consistently measure progress, and communicate with key constituencies and the public. Here we present the second annual global assessment of the Ocean Health Index, reporting current scores and annual changes since 2012, recalculated using updated methods and data based on the best available science, for 221 coastal countries and territories. The Index measures performance of ten societal goals for healthy oceans on a quantitative scale of increasing health from 0 to 100, and combines these scores into a single Index score, for each country and globally. The global Index score improved one point (from 67 to 68), while many country-level Index and goal scores had larger changes. Per-country Index scores ranged from 41–95 and, on average, improved by 0.06 points (range -8 to +12). Globally, average scores increased for individual goals by as much as 6.5 points (coastal economies) and decreased by as much as 1.2 points (natural products). Annual updates of the Index, even when not all input data have been updated, provide valuable information to scientists, policy makers, and resource managers because patterns and trends can emerge from the data that have been updated. Changes of even a few points indicate potential successes (when scores increase) that merit recognition, or concerns (when scores decrease) that may require mitigative action, with changes of more than 10–20 points representing large shifts that deserve greater attention. Goal scores showed remarkably little covariance across regions, indicating low redundancy in the Index, such that each goal delivers information about a different facet of ocean health. Together these scores provide a snapshot of global ocean health and suggest where countries have made progress and where a need for further improvement exists. PMID:25774678

  13. Patterns and emerging trends in global ocean health.

    PubMed

    Halpern, Benjamin S; Longo, Catherine; Lowndes, Julia S Stewart; Best, Benjamin D; Frazier, Melanie; Katona, Steven K; Kleisner, Kristin M; Rosenberg, Andrew A; Scarborough, Courtney; Selig, Elizabeth R

    2015-01-01

    International and regional policies aimed at managing ocean ecosystem health need quantitative and comprehensive indices to synthesize information from a variety of sources, consistently measure progress, and communicate with key constituencies and the public. Here we present the second annual global assessment of the Ocean Health Index, reporting current scores and annual changes since 2012, recalculated using updated methods and data based on the best available science, for 221 coastal countries and territories. The Index measures performance of ten societal goals for healthy oceans on a quantitative scale of increasing health from 0 to 100, and combines these scores into a single Index score, for each country and globally. The global Index score improved one point (from 67 to 68), while many country-level Index and goal scores had larger changes. Per-country Index scores ranged from 41-95 and, on average, improved by 0.06 points (range -8 to +12). Globally, average scores increased for individual goals by as much as 6.5 points (coastal economies) and decreased by as much as 1.2 points (natural products). Annual updates of the Index, even when not all input data have been updated, provide valuable information to scientists, policy makers, and resource managers because patterns and trends can emerge from the data that have been updated. Changes of even a few points indicate potential successes (when scores increase) that merit recognition, or concerns (when scores decrease) that may require mitigative action, with changes of more than 10-20 points representing large shifts that deserve greater attention. Goal scores showed remarkably little covariance across regions, indicating low redundancy in the Index, such that each goal delivers information about a different facet of ocean health. Together these scores provide a snapshot of global ocean health and suggest where countries have made progress and where a need for further improvement exists. PMID:25774678

  14. Distribution of mesozooplankton biomass in the global ocean

    NASA Astrophysics Data System (ADS)

    Moriarty, R.; O'Brien, T. D.

    2013-02-01

    Mesozooplankton are cosmopolitan within the sunlit layers of the global ocean. They are important in the pelagic food web, having a significant feedback to primary production through their consumption of phytoplankton and microzooplankton. In many regions of the global ocean, they are also the primary contributors to vertical particle flux in the oceans. Through both they affect the biogeochemical cycling of carbon and other nutrients in the oceans. Little, however, is known about their global distribution and biomass. While global maps of mesozooplankton biomass do exist in the literature, they are usually in the form of hand-drawn maps for which the original data associated with these maps are not readily available. The dataset presented in this synthesis has been in development since the late 1990s, is an integral part of the Coastal and Oceanic Plankton Ecology, Production, and Observation Database (COPEPOD), and is now also part of a wider community effort to provide a global picture of carbon biomass data for key plankton functional types, in particular to support the development of marine ecosystem models. A total of 153 163 biomass values were collected, from a variety of sources, for mesozooplankton. Of those 2% were originally recorded as dry mass, 26% as wet mass, 5% as settled volume, and 68% as displacement volume. Using a variety of non-linear biomass conversions from the literature, the data have been converted from their original units to carbon biomass. Depth-integrated values were then used to calculate an estimate of mesozooplankton global biomass. Global epipelagic mesozooplankton biomass, to a depth of 200 m, had a mean of 5.9 μg C L-1, median of 2.7 μg C L-1 and a standard deviation of 10.6 μg C L-1. The global annual average estimate of mesozooplankton in the top 200 m, based on the median value, was 0.19 Pg C. Biomass was highest in the Northern Hemisphere, and there were slight decreases from polar oceans (40-90°) to more temperate

  15. Satellite Altimetry for a Global Ocean Observing System

    NASA Technical Reports Server (NTRS)

    Fu, Lee-Lueng

    2000-01-01

    Space-age technologies have made satellite remote sensing a powerful new tool to study the Earth on a global scale. However, the opacity of the ocean to electromagnetic sensing has limited spaceborne measurements to the properties of the surface layer of the ocean (such as sea surface temperature and color). The radar altimetric measurement of the height of the sea surface relative to the geoid, the dynamic topography of the ocean, is a very useful quantity for studying the circulation of the ocean. The ability of measuring dynamic topography from space makes satellite altimetry a uniquely useful remote sensing technique because dynamic topography reflects oceanic processes not only at the surface but at depths as well. A simple analysis shows that a one centimeter tilt in the dynamic topography is associated with a mass transport of 1-7 Sv (1Sv= 1 million tons per second) in the open ocean depending on the vertical distribution of current velocity. Such a magnitude is an appreciable fraction of the transport of the Florida Current (circa 30 Sv), for instance. TOPEX/POSEIDON has demonstrated the capability of measuring the time variation of sea level with accuracy approaching to 2 cm when the data are averaged over boxes with several hundred kilometers on each side. The data set has been used for studying ocean circulation phenomena with a wide range of scales, ranging from fast-changing barotropic variability to seasonal and interannual variability such as El Nino and La Nina. The long record of precise measurement of global sea level has also showed great promise for monitoring the variation of mean sea level, an effective indicator of global climate change. Continuation of satellite altimetry missions with capability matching or better than that of TOPEX/POSEIDON should be included as a key component of a Global Ocean Observing System. NASA and CNES have committed to continuing the measurement of TOPEX/POSEIDON with a series of follow-on missions called Jason

  16. The Mercator-Ocean Forecasting Service: a 4D vision of the Global Ocean, Serving the Ocean Services

    NASA Astrophysics Data System (ADS)

    Toumazou, V.; Baudel, S.; Vinay, G.; Nouel, L.

    2005-12-01

    Mercator-Ocean is a public interest grouping formed in Toulouse in early 2002 by six major players in the French oceanography community: the space agency CNES, the scientific research centre CNRS, IFREMER (the institute of marine research and exploration), the development research institute IRD, the Meteo-France weather service, and SHOM (the French Navy's hydrography & oceanography department). In 1995, these same organizations gave themselves seven years to achieve a challenging objective: to conceive, develop and implement France's first operational oceanography system. The unique system would be capable of describing, analysing and predicting conditions at the ocean surface and subsurface in real time, anytime, anywhere in the world, even in the most inhospitable seas. That objective was met on 17 January 2001 with the release of the first Mercator ocean bulletin, providing a two-week forecast for the entire North Atlantic. Two thousands new forecast charts are now added to the MERCATOR bulletin every week. Building on these successes, a dedicated operational oceanography team, Mercator Ocean, was set up in 2002. Mercator-Ocean's mission is to deliver incremental improvements in the service provided by this new operational oceanography capability by increasing the resolution and the geographic coverage of the models used. The current high-resolution model offers a 6 km grid resolution, and the first models offering global ocean coverage has been implemented early 2004. A 1/4(°) model will be operated by the end of 2006. Objective 1- Develop an operational oceanography system using three-dimensional simulation and a high-resolution primitive-equation model capable of assimilating satellite data (from the Jason altimetry satellite in particular) and in-situ ocean observation data (particularly those gathered by the CORIOLIS centre). 2- Support applications for commercial shipping and naval forces, promote sustainable stewardship of the world's oceans

  17. Evaluation of the Global Ocean Data Assimilation System at INCOIS: The Tropical Indian Ocean

    NASA Astrophysics Data System (ADS)

    Ravichandran, M.; Behringer, D.; Sivareddy, S.; Girishkumar, M. S.; Chacko, Neethu; Harikumar, R.

    2013-09-01

    A new version of NCEP's Global Ocean Data Assimilation System (GODAS), which is based on the Geophysical Fluid Dynamics Laboratory (GFDL) Modular ocean Model version 4.0 (MOM4.0) and a three-dimensional variational (3D-VAR) data assimilation scheme, was configured and operationalized at Indian National Centre for Ocean Information Services (INCOIS). The primary objective of the GODAS at INCOIS (INCOIS-GODAS) is to provide an accurate estimate of the ocean state, which will be used to initialize a coupled model for the seasonal monsoon forecast and also to understand the variability of the ocean at different time scales. In this paper, we assess the quality of ocean analyses in the Tropical Indian Ocean (TIO) obtained from the operational INCOIS-GODAS. In addition to this, we examined the sensitivity of INCOIS-GODAS to different momentum forcing and to the assimilation of temperature and synthetic salinity based on the experiments carried out with different wind products: NCEP2 and QuikSCAT and a free run respectively. The present study reveals that the model with assimilation simulates most of the observed features of temperature, SSHA and currents with reasonably good accuracy in the TIO at both intra-seasonal and inter-annual time scales. The analysis further shows that there was a considerable improvement in the ocean current field, when the model was forced with QuikSCAT winds.

  18. An eddy-resolving model of the Global Ocean

    NASA Astrophysics Data System (ADS)

    Ibrayev, Rashit; Khabeev, Renat; Kalmykov, Vladimir; Ushakov, Konstantin

    2013-04-01

    We present results of eddy-resolving simulation of the global ocean with INM-IO general circulation model. The global grid employs tripole layout, has 0.1-degree horizontal resolution, and uses 49 vertical levels. The ocean model coupled with sea ice and atmospheric boundary layer sub-models. We address to the problem of effective implementation of the numerical code on parallel computers. The model was developed in the Institute of Numerical Mathematics (INM) and P.P.Shirshov Institute of Oceanology (IO). The global simulations were performed with atmospheric conditions based on repeat annual cycle of the normal year - CORE dataset. We present an overview from 75-year spinup. The model results are quite good when compared to observations. We discuss the results of sensitivity of AMOC to the fresh water input due to Greenland ice sheet melting.

  19. Integrated studies of uncultured microbes in the global ocean (Invited)

    NASA Astrophysics Data System (ADS)

    Dupont, C.; Rusch, D.; Martiny, A.; Lasken, R.

    2010-12-01

    The Global Ocean Sampling (GOS) initiative at the J. Craig Venter Institute represents the most extensive metagenomic study of a single environment. Early findings highlighted the potential of shotgun metagenomics to expand our knowledge of marine microbial biodiversity and physiology. However, it also became clear that many of the abundant marine microbes remain uncultured, hindering a direct connection between phylogeny and ecophysiology. In two recent studies, a combination of single cell genomics and aggressive assembly of binned metagenomic data have resulted in the acquisition of multiple genomes for two uncultured but globally relevant organisms. Metabolic reconstructions of the whole genomes revealed unique physiological adaptations in marine Prochlorococcus to high nutrient, low Fe regions of the global ocean and illuminated the potential ecological role of the gamma-proteobacterial 16S clade SAR86. The internal reference genomes also facilitate fragment recruitment based biogeographical studies, both at the whole genome level and the protein level.

  20. Mercator-Ocean monitoring and forecasting : a 4D vision of the global ocean

    NASA Astrophysics Data System (ADS)

    Bahurel, P.; Toumazou, V.

    Mercator Ocean is a public interest grouping formed in Toulouse in early 2002 by six major players in the French oceanography community: the space agency CNES, the scientific research centre CNRS, IFREMER (the institute of marine research and exploration), the development research institute IRD, the Météo France weather service, and SHOM (the French Navy's hydrography & oceanography department). In 1995, these same organizations gave themselves seven years to achieve a challenging objective: to conceive, develop and implement France's first operational oceanography system. The unique system would be capable of describing, analysing and predicting conditions at the ocean surface and subsurface in real time, anytime, anywhere in the world, even in the most inhospitable seas. That objective was met on 17 January 2001 with the release of the first Mercator ocean bulletin, providing a two-week forecast for the entire North Atlantic. Two thousands new forecast charts are now added to the MERCATOR bulletin every week. Building on these successes, a dedicated operational oceanography team, Mercator Ocean, was set up in 2002. Mercator Ocean's mission is to deliver incremental improvements in the service provided by this new operational oceanography capability by increasing the resolution and the geographic coverage of the models used. The new high-resolution model that is now on line offers 6 km grid resolution, and the first models offering global ocean coverage will be implemented in 2004. Over the next four years, Mercator Ocean also plans to establish a European Operational Oceanography Centre in Toulouse. Objective 1. Develop an operational oceanography system using three-dimensional simulation and a high-resolution primitive-equation model capable of assimilating satellite data (from the Jason altimetry satellite in particular) and in-situ ocean observation data (particularly those gathered by the CORIOLIS centre). 2. Support applications for commercial shipping and

  1. Impacts of data assimilation on the global ocean carbonate system

    NASA Astrophysics Data System (ADS)

    Visinelli, L.; Masina, S.; Vichi, M.; Storto, A.; Lovato, T.

    2016-06-01

    In an ocean reanalysis, historical observations are combined with ocean and biogeochemical general circulation models to produce a reconstruction of the oceanic properties in past decades. This is one possible method to better constrain the role of the ocean carbon cycle in the determination of the air-sea CO2 flux. In this work, we investigate how the assimilation of physical variables and subsequently the combined assimilation of physical data and inorganic carbon variables - namely dissolved inorganic carbon (DIC) and alkalinity - affect the modelling of the marine carbonate system and the related air-sea CO2 fluxes. The performance of the two assimilation exercises are quantitatively assessed against the assimilated DIC and alkalinity data and the independent ocean surface pCO2 observations from global datasets. We obtain that the assimilation of physical observations has contrasting effects in different ocean basins when compared with the DIC and alkalinity data: it reduces the root-mean square error against the observed pCO2 in the Atlantic and Southern oceans, while increases the model error in the North Pacific and Indian Oceans. In both cases the corrected evaporation rates are the major factor determining the changes in concentrations. The assimilation of inorganic carbon variables on top of the physical data gives a generalized improvement in the model error of inorganic carbon variables, also improving the annual mean and spatial distribution of air-sea fluxes in agreement with other published estimates. These results indicate that data assimilation of physical and inorganic carbon data does not guarantee the improvement of the simulated pCO2 in all the oceanic regions; nevertheless, errors in pCO2 are reduced by a factor corresponding to those associated with the air-sea flux formulations.

  2. Global Hydrographic Overview of Ocean Near Surface Variability

    NASA Astrophysics Data System (ADS)

    von Schuckmann, K.; Gaillard, F.; Le Traon, P.

    2007-12-01

    Estimates of hydrographic variability as measured by ARGO drifters in the near surface layer of the world ocean are discussed here. A gridded global field of these hydrographic measurements is used which is disposed by the CORIOLIS Analysis System (CAS). The estimates explicitly include the description of the seasonal cycle of temperature as well as of the salinity field, depict large-scale variability patterns in the different oceanic basins and its main purpose is to provide an insight into what can be measured and resolved in the upper layer while using the CAS gridded field. Amplitudes of total variance are generally higher in the northern hemisphere compared to its southern counterpart. The distribution of standard deviations of temperature including the seasonal cycle as well as from temperature anomalies highly differs from corresponding salinity variability which can be predominantly lead back to ocean atmosphere dynamics. Large-scale and well known oceanic features such as ocean's response to NAO and PDO fluctuations and ENSO dynamics can be resolved in CAS temperatures. A substantial advance using the CAS gridded field is that its signatures in global salinity can also be discussed.

  3. Beyond peak reservoir storage? A global estimate of declining water storage capacity in large reservoirs

    NASA Astrophysics Data System (ADS)

    Wisser, Dominik; Frolking, Steve; Hagen, Stephen; Bierkens, Marc F. P.

    2013-09-01

    Water storage is an important way to cope with temporal variation in water supply and demand. The storage capacity and the lifetime of water storage reservoirs can be significantly reduced by the inflow of sediments. A global, spatially explicit assessment of reservoir storage loss in conjunction with vulnerability to storage loss has not been done. We estimated the loss in reservoir capacity for a global data set of large reservoirs from 1901 to 2010, using modeled sediment flux data. We use spatially explicit population data sets as a proxy for storage demand and calculate storage capacity for all river basins globally. Simulations suggest that the net reservoir capacity is declining as a result of sedimentation (˜5% compared to the installed capacity). Combined with increasing need for storage, these losses challenge the sustainable management of reservoir operation and water resources management in many regions. River basins that are most vulnerable include those with a strong seasonal flow pattern and high population growth rates such as the major river basins in India and China. Decreasing storage capacity globally suggests that the role of reservoir water storage in offsetting sea-level rise is likely weakening and may be changing sign.

  4. Towards understanding global variability in ocean carbon-13

    NASA Astrophysics Data System (ADS)

    Tagliabue, Alessandro; Bopp, Laurent

    2008-03-01

    We include a prognostic parameterization of carbon-13 into a global ocean-biogeochemistry model to investigate the spatiotemporal variability in ocean carbon-13 between 1860 and 2000. Carbon-13 was included in all 10 existing carbon pools, with dynamic fractionations occurring during photosynthesis, gas exchange and carbonate chemistry. We find that ocean distributions of δ13CDIC at any point in time are controlled by the interplay between biological fractionation, gas exchange, and ocean mixing. In particular, the deep ocean δ13CDIC is sensitive (by > 0.5‰) to the degree of ocean ventilation. On interannual timescales, although the variability in δ13CDIC is a first order function of the atmospheric δ13CO2 and overall carbon flux, the spatial distributions are controlled by the degree to which surface waters are exposed to the atmosphere. The δ13CPOC is highly sensitive to the species of inorganic carbon assimilated during photosynthesis (by 10 to 17‰), as well as the intrinsic growth rate and in situ [CO2(aq)], suggesting that phytoplankton utilize both HCO3- and CO2(aq). The relationship between Δδ13CDIC and anthropogenic carbon (Cant) varies by ±70% regionally and circulation and biotic effects can influence estimates of Cant that are based on Δδ13CDIC.

  5. A Coupled Ocean General Circulation, Biogeochemical, and Radiative Model of the Global Oceans: Seasonal Distributions of Ocean Chlorophyll and Nutrients

    NASA Technical Reports Server (NTRS)

    Gregg, Watson W.; Busalacchi, Antonio (Technical Monitor)

    2000-01-01

    A coupled ocean general circulation, biogeochemical, and radiative model was constructed to evaluate and understand the nature of seasonal variability of chlorophyll and nutrients in the global oceans. Biogeochemical processes in the model are determined from the influences of circulation and turbulence dynamics, irradiance availability. and the interactions among three functional phytoplankton groups (diatoms. chlorophytes, and picoplankton) and three nutrients (nitrate, ammonium, and silicate). Basin scale (greater than 1000 km) model chlorophyll results are in overall agreement with CZCS pigments in many global regions. Seasonal variability observed in the CZCS is also represented in the model. Synoptic scale (100-1000 km) comparisons of imagery are generally in conformance although occasional departures are apparent. Model nitrate distributions agree with in situ data, including seasonal dynamics, except for the equatorial Atlantic. The overall agreement of the model with satellite and in situ data sources indicates that the model dynamics offer a reasonably realistic simulation of phytoplankton and nutrient dynamics on synoptic scales. This is especially true given that initial conditions are homogenous chlorophyll fields. The success of the model in producing a reasonable representation of chlorophyll and nutrient distributions and seasonal variability in the global oceans is attributed to the application of a generalized, processes-driven approach as opposed to regional parameterization and the existence of multiple phytoplankton groups with different physiological and physical properties. These factors enable the model to simultaneously represent many aspects of the great diversity of physical, biological, chemical, and radiative environments encountered in the global oceans.

  6. Global declines in oceanic nitrification rates as a consequence of ocean acidification.

    PubMed

    Beman, J Michael; Chow, Cheryl-Emiliane; King, Andrew L; Feng, Yuanyuan; Fuhrman, Jed A; Andersson, Andreas; Bates, Nicholas R; Popp, Brian N; Hutchins, David A

    2011-01-01

    Ocean acidification produced by dissolution of anthropogenic carbon dioxide (CO(2)) emissions in seawater has profound consequences for marine ecology and biogeochemistry. The oceans have absorbed one-third of CO(2) emissions over the past two centuries, altering ocean chemistry, reducing seawater pH, and affecting marine animals and phytoplankton in multiple ways. Microbially mediated ocean biogeochemical processes will be pivotal in determining how the earth system responds to global environmental change; however, how they may be altered by ocean acidification is largely unknown. We show here that microbial nitrification rates decreased in every instance when pH was experimentally reduced (by 0.05-0.14) at multiple locations in the Atlantic and Pacific Oceans. Nitrification is a central process in the nitrogen cycle that produces both the greenhouse gas nitrous oxide and oxidized forms of nitrogen used by phytoplankton and other microorganisms in the sea; at the Bermuda Atlantic Time Series and Hawaii Ocean Time-series sites, experimental acidification decreased ammonia oxidation rates by 38% and 36%. Ammonia oxidation rates were also strongly and inversely correlated with pH along a gradient produced in the oligotrophic Sargasso Sea (r(2) = 0.87, P < 0.05). Across all experiments, rates declined by 8-38% in low pH treatments, and the greatest absolute decrease occurred where rates were highest off the California coast. Collectively our results suggest that ocean acidification could reduce nitrification rates by 3-44% within the next few decades, affecting oceanic nitrous oxide production, reducing supplies of oxidized nitrogen in the upper layers of the ocean, and fundamentally altering nitrogen cycling in the sea. PMID:21173255

  7. Anthropogenic CO2 estimates in the Southern Ocean: Storage partitioning in the different water masses

    NASA Astrophysics Data System (ADS)

    Pardo, Paula C.; Pérez, F. F.; Khatiwala, S.; Ríos, A. F.

    2014-01-01

    The role of the Southern Ocean (SO) remains a key issue in our understanding of the global carbon cycle and for predicting future climate change. A number of recent studies suggest that 30 to 40% of ocean uptake of anthropogenic carbon (CANT) occurs in the SO, accompanied by highly efficient transport of CANT by intermediate-depth waters out of that region. In contrast, storage of CANT in deep and bottom layers is still an open question. Significant discrepancies can be found between results from several indirect techniques and ocean models. Even though reference methodologies state that CANT concentrations in deep and bottom layers of the SO are negligible, recent results from tracer-based methods and ocean models as well as accurate measurements of 39Ar, CCl4 and CFCs along the continental slope and in the Antarctic deep and bottom waters contradict this conclusion. The role of the SO in the uptake, storage and transport of CANT has proved to be really important for the global ocean and there is a need for agreement between the different techniques. A CO2-data-based ("back-calculation") method, the CT0 method, was developed with the aim of obtaining more accurate CANT concentration and inventory estimates in the SO region (south of 45°S). Data from the GLODAP (Global Ocean Data Analysis Project) and CARINA databases were used. The CT0 method tries to reduce at least two of the main caveats attributed to the back-calculation methods: the need for a better definition of water mass mixing and, most importantly, the unsteady state of the air-sea CO2 disequilibrium (ΔCdis) term. Water mass mixing was computed on the basis of results from an extended Optimum Multi-Parametric (eOMP) analysis applied to the main water masses of the SO. Recently published parameterizations were used to obtain more reliable values of ΔCdis and also of preformed alkalinity. The variability of the ΔCdis term (δCdis) was approximated using results from an ocean carbon cycle model

  8. Distribution of mesozooplankton biomass in the global ocean

    NASA Astrophysics Data System (ADS)

    Moriarty, R.; O'Brien, T. D.

    2012-09-01

    Mesozooplankton are cosmopolitan within the sunlit layers of the global ocean. They are important in the classical food web, having a significant feedback to primary production through their consumption of phytoplankton and microzooplankton. They are also the primary contributor to vertical particle flux in the oceans. Through both they affect the biogeochemical cycling of carbon and other nutrients in the oceans. Little, however, is known about their global distribution and biomass. While global maps of mesozooplankton biomass do exist in the literature they are usually in the form of hand-drawn maps and the original data associated with these maps are not readily available. The dataset presented in this synthesis has been in development since the late 1990's, is an integral part of the Coastal & Oceanic Plankton Ecology, Production, & Observation Database (COPEPOD), and is now also part of a wider community effort to provide a global picture of carbon biomass data for key plankton functional types, in particular to support the development of marine ecosystem models. A total of 153 163 biomass values were collected, from a variety of sources, for mesozooplankton. Of those 2% were originally recorded as dry mass, 26% as wet mass, 5% as settled volume, and 68% as displacement volume. Using a variety of non-linear biomass conversions from the literature, the data have been converted from their original units to carbon biomass. Depth-integrated values were then used to calculate mesozooplankton global biomass. Global mesozooplankton biomass, to a depth of 200 m, had a mean of 5.9 μg C l-1, median of 2.7 μg C l-1 and a standard deviation of 10.6 μg C l-1. The global annual average estimate of mesozooplankton, based on the median value, was 0.19 Pg C. Biomass was highest in the Northern Hemisphere, but the general trend shows a slight decrease from polar oceans to temperate regions with values increasing again in the tropics. Gridded dataset

  9. An ensemble of eddy-permitting global ocean reanalyses from the MyOcean project

    NASA Astrophysics Data System (ADS)

    Masina, Simona; Storto, Andrea; Ferry, Nicolas; Valdivieso, Maria; Haines, Keith; Balmaseda, Magdalena; Zuo, Hao; Drevillon, Marie; Parent, Laurent

    2015-07-01

    A set of four eddy-permitting global ocean reanalyses produced in the framework of the MyOcean project have been compared over the altimetry period 1993-2011. The main differences among the reanalyses used here come from the data assimilation scheme implemented to control the ocean state by inserting reprocessed observations of sea surface temperature (SST), in situ temperature and salinity profiles, sea level anomaly and sea-ice concentration. A first objective of this work includes assessing the interannual variability and trends for a series of parameters, usually considered in the community as essential ocean variables: SST, sea surface salinity, temperature and salinity averaged over meaningful layers of the water column, sea level, transports across pre-defined sections, and sea ice parameters. The eddy-permitting nature of the global reanalyses allows also to estimate eddy kinetic energy. The results show that in general there is a good consistency between the different reanalyses. An intercomparison against experiments without data assimilation was done during the MyOcean project and we conclude that data assimilation is crucial for correctly simulating some quantities such as regional trends of sea level as well as the eddy kinetic energy. A second objective is to show that the ensemble mean of reanalyses can be evaluated as one single system regarding its reliability in reproducing the climate signals, where both variability and uncertainties are assessed through the ensemble spread and signal-to-noise ratio. The main advantage of having access to several reanalyses differing in the way data assimilation is performed is that it becomes possible to assess part of the total uncertainty. Given the fact that we use very similar ocean models and atmospheric forcing, we can conclude that the spread of the ensemble of reanalyses is mainly representative of our ability to gauge uncertainty in the assimilation methods. This uncertainty changes a lot from one ocean

  10. The timescales of global surface-ocean connectivity.

    PubMed

    Jönsson, Bror F; Watson, James R

    2016-01-01

    Planktonic communities are shaped through a balance of local evolutionary adaptation and ecological succession driven in large part by migration. The timescales over which these processes operate are still largely unresolved. Here we use Lagrangian particle tracking and network theory to quantify the timescale over which surface currents connect different regions of the global ocean. We find that the fastest path between two patches--each randomly located anywhere in the surface ocean--is, on average, less than a decade. These results suggest that marine planktonic communities may keep pace with climate change--increasing temperatures, ocean acidification and changes in stratification over decadal timescales--through the advection of resilient types. PMID:27093522

  11. Intercomparison of Latent Heat Fluxes Over Global Oceans

    NASA Technical Reports Server (NTRS)

    Chou, Shu-Hsien; Nelkin, Eric; Ardizzone, Joe; Atlas, Robert M.; Chou, Ming-Dah

    2003-01-01

    Turbulent fluxes of momentum, moisture, and heat at the air-sea interface are essential for climate studies. Version 2 Goddard Satellite-based Surface Turbulent Fluxes (GSSTF2) has been derived from the Special Sensor Microwave/Imager (SSM/I) radiance measurements. This dataset, covering the period July 1987-December 2000 over global oceans, has a spatial resolution of 1 deg x 1 deg lat-long and a temporal resolution of 1 day. Turbulent fluxes are derived from the SSM/I surface winds and surface air humidity, as well as the 2-m air and sea surface temperatures (SST) of the NCEP/NCAR reanalysis, using a bulk aerodynamic algorithm based on the surface layer similarity theory. The GSSTF2 bulk flux model, and retrieved daily wind stress, latent heat flux, wind speed, and surface air humidity validate well with ship observations of ten field experiments over the tropical and midlatitude oceans during 1991-99. The global distributions of 1988-2000 annual- and seasonal-mean turbulent fluxes show reasonable patterns related to the atmospheric general circulation and seasonal variations. Latent heat fluxes and related input parameters over global oceans during 1992-93 have been compared among GSSTF1 (version 1), GSSTF2, HOAPS (Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data), NCEP/NCAR reanalysis, and one based on COADS (Comprehensive Ocean-Atmosphere Data Set). Our analyses suggest that the GSSTF2 latent heat flux, surface air humidity, surface wind, and SST are quite realistic compared to the other four flux datasets examined. However, significant differences are found among these five flux datasets. The GSSTF2, available at http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/hydrology/hd_gsstf2.O.html, is useful for climate studies.

  12. Climatological distribution of aragonite saturation state in the global oceans

    NASA Astrophysics Data System (ADS)

    Jiang, Li-Qing; Feely, Richard A.; Carter, Brendan R.; Greeley, Dana J.; Gledhill, Dwight K.; Arzayus, Krisa M.

    2015-10-01

    Aragonite saturation state (Ωarag) in surface and subsurface waters of the global oceans was calculated from up-to-date (through the year of 2012) ocean station dissolved inorganic carbon (DIC) and total alkalinity (TA) data. Surface Ωarag in the open ocean was always supersaturated (Ω > 1), ranging between 1.1 and 4.2. It was above 2.0 (2.0-4.2) between 40°N and 40°S but decreased toward higher latitude to below 1.5 in polar areas. The influences of water temperature on the TA/DIC ratio, combined with the temperature effects on inorganic carbon equilibrium and apparent solubility product (K'sp), explain the latitudinal differences in surface Ωarag. Vertically, Ωarag was highest in the surface mixed layer. Higher hydrostatic pressure, lower water temperature, and more CO2 buildup from biological activity in the absence of air-sea gas exchange helped maintain lower Ωarag in the deep ocean. Below the thermocline, aerobic decomposition of organic matter along the pathway of global thermohaline circulation played an important role in controlling Ωarag distributions. Seasonally, surface Ωarag above 30° latitudes was about 0.06 to 0.55 higher during warmer months than during colder months in the open-ocean waters of both hemispheres. Decadal changes of Ωarag in the Atlantic and Pacific Oceans showed that Ωarag in waters shallower than 100 m depth decreased by 0.10 ± 0.09 (-0.40 ± 0.37% yr-1) on average from the decade spanning 1989-1998 to the decade spanning 1998-2010.

  13. Enceladus's measured physical libration requires a global subsurface ocean

    NASA Astrophysics Data System (ADS)

    Thomas, P. C.; Tajeddine, R.; Tiscareno, M. S.; Burns, J. A.; Joseph, J.; Loredo, T. J.; Helfenstein, P.; Porco, C.

    2016-01-01

    Several planetary satellites apparently have subsurface seas that are of great interest for, among other reasons, their possible habitability. The geologically diverse saturnian satellite Enceladus vigorously vents liquid water and vapor from fractures within a south polar depression and thus must have a liquid reservoir or active melting. However, the extent and location of any subsurface liquid region is not directly observable. We use measurements of control points across the surface of Enceladus accumulated over seven years of spacecraft observations to determine the satellite's precise rotation state, finding a forced physical libration of 0.120 ± 0.014° (2σ). This value is too large to be consistent with Enceladus's core being rigidly connected to its surface, and thus implies the presence of a global ocean rather than a localized polar sea. The maintenance of a global ocean within Enceladus is problematic according to many thermal models and so may constrain satellite properties or require a surprisingly dissipative Saturn.

  14. The new automatic precipitation phase distinction algorithm for OceanRAIN data over the global ocean

    NASA Astrophysics Data System (ADS)

    Burdanowitz, Jörg; Klepp, Christian; Bakan, Stephan

    2015-04-01

    The hitherto lack of surface precipitation data over the global ocean limits the capabilities to validate recent and future precipitation satellite retrievals. The first systematic ship-based surface precipitation data set OceanRAIN (Ocean Rain And Ice-phase precipitation measurement Network) aims at providing in-situ precipitation data through particle size distributions (PSDs) from optical disdrometers deployed on research vessels (RVs). From the RV Polarstern, OceanRAIN currently contains more than four years of 1-minute resolution precipitation data, which corresponds to more than 200,000 minutes of precipitation. The calculation of the precipitation rate requires to know the precipitation phase (PP) of the falling particles. We develop a novel algorithm to automatically retrieve the PP using OceanRAIN data and ancillary meteorological measurements from RVs. The main objective is to improve accuracy and efficiency of the current time-consuming manual method of discriminating liquid and solid precipitation particles. The new PP distinction algorithm is based on the relation of air temperature and relative humidity (T-rH) with respect to PP. For first-time usage over oceanic areas, the land-retrieved coefficients of this empirical relationship are adjusted to OceanRAIN data. The measured PSD supports determining the PP in certain cases where large snow aggregates exist at distinctly positive air temperatures. The classification, based on T-rH and PSD, is statistically exploited and weighed with respect to the current weather conditions to obtain an overall PP probability at 1-minute resolution. The new PP distinction algorithm agrees in more than 92% (94% excl. mixed-phase) of precipitating cases with the manually-determined PP in the RV Polarstern data. The PP distinction algorithm complements the valuable information of OceanRAIN surface precipitation over the ocean.

  15. A daily global mesoscale ocean eddy dataset from satellite altimetry

    PubMed Central

    Faghmous, James H.; Frenger, Ivy; Yao, Yuanshun; Warmka, Robert; Lindell, Aron; Kumar, Vipin

    2015-01-01

    Mesoscale ocean eddies are ubiquitous coherent rotating structures of water with radial scales on the order of 100 kilometers. Eddies play a key role in the transport and mixing of momentum and tracers across the World Ocean. We present a global daily mesoscale ocean eddy dataset that contains ~45 million mesoscale features and 3.3 million eddy trajectories that persist at least two days as identified in the AVISO dataset over a period of 1993–2014. This dataset, along with the open-source eddy identification software, extract eddies with any parameters (minimum size, lifetime, etc.), to study global eddy properties and dynamics, and to empirically estimate the impact eddies have on mass or heat transport. Furthermore, our open-source software may be used to identify mesoscale features in model simulations and compare them to observed features. Finally, this dataset can be used to study the interaction between mesoscale ocean eddies and other components of the Earth System. PMID:26097744

  16. A daily global mesoscale ocean eddy dataset from satellite altimetry.

    PubMed

    Faghmous, James H; Frenger, Ivy; Yao, Yuanshun; Warmka, Robert; Lindell, Aron; Kumar, Vipin

    2015-01-01

    Mesoscale ocean eddies are ubiquitous coherent rotating structures of water with radial scales on the order of 100 kilometers. Eddies play a key role in the transport and mixing of momentum and tracers across the World Ocean. We present a global daily mesoscale ocean eddy dataset that contains ~45 million mesoscale features and 3.3 million eddy trajectories that persist at least two days as identified in the AVISO dataset over a period of 1993-2014. This dataset, along with the open-source eddy identification software, extract eddies with any parameters (minimum size, lifetime, etc.), to study global eddy properties and dynamics, and to empirically estimate the impact eddies have on mass or heat transport. Furthermore, our open-source software may be used to identify mesoscale features in model simulations and compare them to observed features. Finally, this dataset can be used to study the interaction between mesoscale ocean eddies and other components of the Earth System. PMID:26097744

  17. Eddy Permitting Simulations of Biogeochemical Cycles in the Global Ocean

    NASA Astrophysics Data System (ADS)

    Sumata, H.; Hashioka, T.; Suzuki, T.; Yamanaka, Y.

    2008-12-01

    A 3D ecosystem-biogeochemical model simulation for the global domain is performed in order to investigate variability of oceanic ecosystem on time scales of years to decades. The model has a horizontal resolution of 1/4 times 1/6 degrees and 51 vertical levels, covering the entire domain of the world ocean. The ecosystem- biogeochemical part of the model is based on NEMURO (North Pacific Ecosystem Model Used for Regional Oceanography), and is coupled with CCSR Ocean Component Model (COCO) version 4.3 by an offline technique. The physical part of the model is driven by the inter-annual forcing by common ocean-ice reference experiments (CORE) data from 1958 to 2004, and reasonably simulates inter-annual to decadal variabilities of ocean conditions related to biogeochemical cycles. These properties of the physical model with its eddying filed enable us to reproduce the realistic distributions of nutrients and plankton productions. Comparisons with historical station data show that the model also reasonably simulates the observed variabilities of ecosystem on time scales of years to decades. In particular, the model captures the transitions of biogeochemical cycles associated with regime shifts.

  18. Global biogeography of Prochlorococcus genome diversity in the surface ocean.

    PubMed

    Kent, Alyssa G; Dupont, Chris L; Yooseph, Shibu; Martiny, Adam C

    2016-08-01

    Prochlorococcus, the smallest known photosynthetic bacterium, is abundant in the ocean's surface layer despite large variation in environmental conditions. There are several genetically divergent lineages within Prochlorococcus and superimposed on this phylogenetic diversity is extensive gene gain and loss. The environmental role in shaping the global ocean distribution of genome diversity in Prochlorococcus is largely unknown, particularly in a framework that considers the vertical and lateral mechanisms of evolution. Here we show that Prochlorococcus field populations from a global circumnavigation harbor extensive genome diversity across the surface ocean, but this diversity is not randomly distributed. We observed a significant correspondence between phylogenetic and gene content diversity, including regional differences in both phylogenetic composition and gene content that were related to environmental factors. Several gene families were strongly associated with specific regions and environmental factors, including the identification of a set of genes related to lower nutrient and temperature regions. Metagenomic assemblies of natural Prochlorococcus genomes reinforced this association by providing linkage of genes across genomic backbones. Overall, our results show that the phylogeography in Prochlorococcus taxonomy is echoed in its genome content. Thus environmental variation shapes the functional capabilities and associated ecosystem role of the globally abundant Prochlorococcus. PMID:26836261

  19. Global root zone storage capacity from satellite-based evaporation

    NASA Astrophysics Data System (ADS)

    Wang-Erlandsson, Lan; Bastiaanssen, Wim G. M.; Gao, Hongkai; Jägermeyr, Jonas; Senay, Gabriel B.; van Dijk, Albert I. J. M.; Guerschman, Juan P.; Keys, Patrick W.; Gordon, Line J.; Savenije, Hubert H. G.

    2016-04-01

    This study presents an "Earth observation-based" method for estimating root zone storage capacity - a critical, yet uncertain parameter in hydrological and land surface modelling. By assuming that vegetation optimises its root zone storage capacity to bridge critical dry periods, we were able to use state-of-the-art satellite-based evaporation data computed with independent energy balance equations to derive gridded root zone storage capacity at global scale. This approach does not require soil or vegetation information, is model independent, and is in principle scale independent. In contrast to a traditional look-up table approach, our method captures the variability in root zone storage capacity within land cover types, including in rainforests where direct measurements of root depths otherwise are scarce. Implementing the estimated root zone storage capacity in the global hydrological model STEAM (Simple Terrestrial Evaporation to Atmosphere Model) improved evaporation simulation overall, and in particular during the least evaporating months in sub-humid to humid regions with moderate to high seasonality. Our results suggest that several forest types are able to create a large storage to buffer for severe droughts (with a very long return period), in contrast to, for example, savannahs and woody savannahs (medium length return period), as well as grasslands, shrublands, and croplands (very short return period). The presented method to estimate root zone storage capacity eliminates the need for poor resolution soil and rooting depth data that form a limitation for achieving progress in the global land surface modelling community.

  20. El Nino and the Global Ocean Observing System

    NASA Technical Reports Server (NTRS)

    Halpern, David

    1999-01-01

    Until a decade ago, an often-quoted expression in oceanography is that very few observations are recorded throughout the ocean. Now, the sentiment is no longer valid in the uppermost 10% of the tropical Pacific Ocean nor at the surface of the global ocean. One of the remarkable legacies of the 1985-1994 Tropical Oceans Global Atmosphere (TOGA) Program is an in situ marine meteorological and upper oceanographic measurement array throughout the equatorial Pacific to monitor the development and maintenance of El Nino episodes. The TOGA Observing System, which initially consisted of moored- and drifting-buoy arrays, a network of commercial ships, and coastal and island stations, now includes a constellation of satellites and data-assimilating models to simulate subsurface oceanographic conditions. The El Nino and La Nina tropical Pacific Ocean observing system represents the initial phase of an integrated global ocean observing system. Remarkable improvements have been made in ocean model simulation of subsurface currents, but some problems persist. For example, the simulation of the South Equatorial Current (SEC) remains an important challenge in the 2S-2N Pacific equatorial wave guide. During El Nino the SEC at the equator is reduced and sometimes the direction is reversed, becoming eastward. Both conditions allow warm water stored in the western Pacific to invade the eastern region, creating an El Nino episode. Assimilation of data is a tenet of faith to correct simulation errors caused by deficiencies in surface fluxes (especially wind stress) and parameterizations of subgrid-scale physical processes. In the first of two numerical experiments, the Pacific SEC was simulated with and without assimilation of subsurface temperature data. Along the equator, a very weak SEC occurred throughout the eastern Pacific, independent of assimilation of data. However, as displayed in the diagram, in the western Pacific there was no satisfactory agreement between the two

  1. 14C-age tracers in global ocean circulation models

    NASA Astrophysics Data System (ADS)

    Koeve, W.; Wagner, H.; Kähler, P.; Oschlies, A.

    2015-07-01

    The natural abundance of 14C in total CO2 dissolved in seawater (DIC) is a property applied to evaluate the water age structure and circulation in the ocean and in ocean models. In this study we use three different representations of the global ocean circulation augmented with a suite of idealised tracers to study the potential and limitations of using natural 14C to determine water age, which is the time elapsed since a body of water has been in contact with the atmosphere. We find that, globally, bulk 14C-age is dominated by two equally important components, one associated with ageing, i.e. the time component of circulation, and one associated with a "preformed 14C-age". The latter quantity exists because of the slow and incomplete atmosphere-ocean equilibration of 14C particularly in high latitudes where many water masses form. In the ocean's interior, preformed 14C-age behaves like a passive tracer. The relative contribution of the preformed component to bulk 14C-age varies regionally within a given model, but also between models. Regional variability in the Atlantic Ocean is associated with the mixing of waters with very different end members of preformed 14C-age. Here, variations in the preformed component over space and time mask the circulation component to an extent that its patterns are not detectable from bulk 14C-age. Between models, the variability of preformed 14C-age can also be considerable (factor of 2), related to the combination of physical model parameters, which influence circulation dynamics or gas exchange. The preformed component was found to be very sensitive to gas exchange and moderately sensitive to ice cover. In our model evaluation, the choice of the gas-exchange constant from within the currently accepted range of uncertainty had such a strong influence on preformed and bulk 14C-age that if model evaluation would be based on bulk 14C-age, it could easily impair the evaluation and tuning of a model's circulation on global and regional

  2. A global ocean carbon climatology: Results from Global Data Analysis Project (GLODAP)

    SciTech Connect

    Key, Robert; Kozyr, Alexander; Sabine, Chris; Lee, K.; Wanninkhof, R.; Bullister, J.L.; Feely, R. A.; Millero, F. J.; Mordy, C.; Peng, T.-H.

    2004-01-01

    During the 1990s, ocean sampling expeditions were carried out as part of the World Ocean Circulation Experiment (WOCE), the Joint Global Ocean Flux Study (JGOFS), and the Ocean Atmosphere Carbon Exchange Study (OACES). Subsequently, a group of U.S. scientists synthesized the data into easily usable and readily available products. This collaboration is known as the Global Ocean Data Analysis Project (GLODAP). Results were merged into a common format data set, segregated by ocean. For comparison purposes, each ocean data set includes a small number of high-quality historical cruises. The data were subjected to rigorous quality control procedures to eliminate systematic data measurement biases. The calibrated 1990s data were used to estimate anthropogenic CO{sub 2}, potential alkalinity, CFC watermass ages, CFC partial pressure, bomb-produced radiocarbon, and natural radiocarbon. These quantities were merged into the measured data files. The data were used to produce objectively gridded property maps at a 1{sup o} resolution on 33 depth surfaces chosen to match existing climatologies for temperature, salinity, oxygen, and nutrients. The mapped fields are interpreted as an annual mean distribution in spite of the inaccuracy in that assumption. Both the calibrated data and the gridded products are available from the Carbon Dioxide Information Analysis Center. Here we describe the important details of the data treatment and the mapping procedure, and present summary quantities and integrals for the various parameters.

  3. Impact of carbon storage through restoration of drylands on the global carbon cycle

    SciTech Connect

    Keller, A.A.; Goldstein, R.A.

    1998-09-01

    The authors evaluate the potential for global carbon storage in drylands as one of several policy options to reduce buildup of carbon dioxide in the atmosphere. They use the GLOCO model, a global carbon cycle model with eight terrestrial biomes that are described mechanistically in detail in terms of the biological processes that involve carbon and nitrogen cycling and the effect of temperature on these processes. GLOCO also considers low-latitude and high-latitude oceans, each divided further into a surface layer and several deeper layers, with an explicit description of biogeochemical processes occurring in each layer, and exchanges among ocean reservoirs and the atmosphere. GLOCO is used to study the transient response of actual vegetation, which is more realistic than looking at equilibrium conditions of potential vegetation. Using estimates of land suitable for restoration in woodlands, grasslands, and deserts, as well as estimates of the rate at which restoration can proceed, the authors estimate that carbon storage in these biomes can range up to 0.8 billion tons of carbon per year for a combination of land management strategies. A global strategy for reducing atmospheric carbon dioxide concentration will require the implementation of multiple options. The advantage of carbon storage in restored drylands is that it comes as a side benefit to programs that are also justifiable in terms of land management.

  4. Validation of a global finite element sea-ice ocean model

    NASA Astrophysics Data System (ADS)

    Timmermann, R.; Danilov, S.; Schröter, J.

    2009-04-01

    Results from a global Finite Element Sea ice-Ocean Model (FESOM) are evaluated using a wide range of observational datasets. FESOM's ocean component is a primitive-equation, hydrostatic ocean model using isopycnic diffusion and a Gent-McWilliams scheme to parameterize the effects of sub-gridscale turbulence on tracer distribution. Vertical mixing and convection are parameterized as a function of the Richardson number and the Monin-Obukhov length. A finite element dynamic-thermodynamic sea ice-model with elastic-viscous-plastic rheology has been developed and coupled to the ocean component. The model features a prognostic snow layer but neglects internal heat storage. All model components are discretized on a triangular/tetrahedral grid with a continuous, conforming representation of model variables. The coupled model has been run in a global configuration and forced with NCEP daily atmospheric reanalysis data for 1948-2007. Results are analysed with a focus on the Southern Hemisphere. While summer ice extent is underestimated in both hemispheres, winter ice extents are in good agreement with satellite data. Southern Ocean sea ice thickness distribution agrees well with ship-based observations and even quantitatively with data from upwards looking sonars (ULS). Sea ice freezing rates have been validated using repeated salinity profiles from Southern Elephant Seals. Gulf Stream transport is underestimated, but transports of the Kuroshio and the Antarctic Circumpolar Current appear realistic. A comparison of numerical tracer studies to observed CFC distribution indicates that bottom layer ventilation occurs on realistic pathways. Global meridional overturning features a strong Antarctic Bottom Water (AABW) cell, while the formation of North Atlantic Deep Water (NADW) appears to be on the weak side. Besides pure model validation, the study also identifies regions and processes that critically require a locally increased horizontal resolution in order to be represented

  5. 14C-age tracers in global ocean circulation models

    NASA Astrophysics Data System (ADS)

    Koeve, W.; Wagner, H.; Kähler, P.; Oschlies, A.

    2014-10-01

    The natural abundance of 14C in total CO2 dissolved in seawater is a property applied to evaluate the water age structure and circulation in the ocean and in ocean models. In this study we use three different representations of the global ocean circulation augmented with a suite of idealised tracers to study the potential and limitations of using natural 14C to determine water age, the time elapsed since a body of water had contact with the atmosphere. We find that, globally, bulk 14C-age is dominated by two equally important components, one associated with aging, i.e. the time component of circulation and one associated with a "preformed 14C-age". This latter quantity exists because of the slow and incomplete atmosphere/ocean equilibration of 14C in particular in high latitudes where many water masses form. The relative contribution of the preformed component to bulk 14C-age varies regionally within a given model, but also between models. Regional variability, e.g. in the Atlantic Ocean is associated with the mixing of waters with very different end members of preformed 14C-age. In the Atlantic, variations in the preformed component over space and time mask the circulation component to an extent that its patterns are not detectable from bulk 14C-age alone. Between models the variability of age can also be considerable (factor of 2), related to the combinations of physical model parameters, which influence circulation dynamics, and gas exchange in the models. The preformed component was found to be very sensitive to gas exchange and moderately sensitive to ice cover. In our model evaluation exercise, the choice of the gas exchange constant from within the current range of uncertainty had such a strong influence on preformed and bulk 14C-age that if model evaluation would be based on bulk 14C-age it could easily impair the evaluation and tuning of a models circulation on global and regional scales. Based on the results of this study, we propose that considering

  6. A Web-Based Climatology of Global Ocean Winds

    NASA Astrophysics Data System (ADS)

    Risien, C. M.; Chelton, D. B.; Hodges, M. K.

    2004-12-01

    A climatology of winds over the global ocean on a 0.5° x 0.5° grid is under development based on five-years of measurements from the SeaWinds scatterometer. The SeaWinds instrument was launched on 19 June 1999 onboard the QuikSCAT satellite. SeaWinds is an active microwave radar that, using electromagnetic backscatter from the wind roughened ocean surface, measures vector winds with an accuracy equivalent to well-calibrated buoy observations. This five-year climatology is a web-based interactive atlas from which users can retrieve wind statistics, both in tabular and graphic form, for any particular region of interest. The global coverage of the scatterometer data provides valuable information about the wind statistics in the many regions of the world ocean that are sparsely sampled by ships and buoys. One of the anticipated uses of this climatology will be presented via a case study of the NOAA/HAZMAT response to a 2001 oil spill that resulted from the grounding of the tanker "Jessica" at the entrance to Puerto Baquerizo Moreno, in Wreck Bay, on San Cristóbal island, Galápagos.

  7. Global Ocean Integrals and Means, with Trend Implications.

    PubMed

    Wunsch, Carl

    2016-01-01

    Understanding the ocean requires determining and explaining global integrals and equivalent average values of temperature (heat), salinity (freshwater and salt content), sea level, energy, and other properties. Attempts to determine means, integrals, and climatologies have been hindered by thinly and poorly distributed historical observations in a system in which both signals and background noise are spatially very inhomogeneous, leading to potentially large temporal bias errors that must be corrected at the 1% level or better. With the exception of the upper ocean in the current altimetric-Argo era, no clear documentation exists on the best methods for estimating means and their changes for quantities such as heat and freshwater at the levels required for anthropogenic signals. Underestimates of trends are as likely as overestimates; for example, recent inferences that multidecadal oceanic heat uptake has been greatly underestimated are plausible. For new or augmented observing systems, calculating the accuracies and precisions of global, multidecadal sampling densities for the full water column is necessary to avoid the irrecoverable loss of scientifically essential information. PMID:26331897

  8. 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

  9. 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.

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

    PubMed

    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

    2012-04-24

    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

  11. Attenuation coefficient of usable solar radiation of the global oceans

    NASA Astrophysics Data System (ADS)

    Lin, Junfang; Lee, Zhongping; Ondrusek, Michael; Kahru, Mati

    2016-05-01

    Usable solar radiation (USR) represents spectrally integrated solar energy in the spectral range of 400-560 nm, a domain where photons penetrate the most in oceanic waters and thus contribute to photosynthesis and heating at deeper depths. Through purely numerical simulations, it was found that the diffuse attenuation coefficient of downwelling USR (Kd(USR), m-1) is nearly a constant vertically in the upper water column for clear waters and most turbid waters. Subsequently an empirical model was developed to estimate Kd(USR) based on the diffuse attenuation coefficient at 490 nm (Kd(490), m-1). We here evaluate this relationship using data collected from a wide range of oceanic and coastal environments and found that the relationship between Kd(490) and Kd(USR) developed via the numerical simulation is quite robust. We further refined this relationship to extend the applicability to "clearest" natural waters. This refined relationship was then used to produce sample distribution of Kd(USR) of global oceans. As expected, extremely low Kd(USR) (˜0.02 m-1) was observed in ocean gyres, while significantly higher Kd(USR) (˜5.2 m-1) was found in very turbid coastal regions. A useful application of Kd(USR) is to easily and accurately propagate surface USR to deeper depths, potentially to significantly improve the estimation of basin scale primary production and heat fluxes in the upper water column.

  12. Ocean Carbon Cycle Data from the Joint Global Ocean Flux Study (JGOFS)

    DOE Data Explorer

    The U.S. JGOFS program, a component of the U.S Global Change Research Program, grew out of the recommendations of a National Academy of Sciences workshop in 1984. An ambitious goal was set to understand the controls on the concentrations and fluxes of carbon and associated nutrients in the ocean. A new field of ocean biogeochemistry emerged with an emphasis on quality measurements of carbon system parameters and interdisciplinary field studies of the biological, chemical and physical process which control the ocean carbon cycle. U.S. JGOFS, ended in 2005 with the conclusion of the Synthesis and Modeling Project (SMP). Data are available throughout the U.S. JGOFS web site at http://usjgofs.whoi.edu/ and from the U.S. JGOFS Data System at http://usjgofs.whoi.edu/jg/dir/jgofs/. Major named segments of the project are: Bermuda Atlantic Time Series (BATS) Study, Hawaii Ocean Time-series (HOT) Study, Equatorial Pacific Process Study, North Atlantic Bloom Experiment (1989), Arabian Sea Process Study, and the Southern Ocean Process Study.

  13. Assimilation of GRACE-derived oceanic mass distributions with a global ocean circulation model

    NASA Astrophysics Data System (ADS)

    Saynisch, J.; Bergmann-Wolf, I.; Thomas, M.

    2015-02-01

    To study the sub-seasonal distribution and generation of ocean mass anomalies, Gravity Recovery and Climate Experiment (GRACE) observations of daily and monthly resolution are assimilated into a global ocean circulation model with an ensemble-based Kalman-Filter technique. The satellite gravimetry observations are processed to become time-variable fields of ocean mass distribution. Error budgets for the observations and the ocean model's initial state are estimated which contain the full covariance information. The consistency of the presented approach is demonstrated by increased agreement between GRACE observations and the ocean model. Furthermore, the simulations are compared with independent observations from 54 bottom pressure recorders. The assimilation improves the agreement to high-latitude recorders by up to 2 hPa. The improvements are caused by assimilation-induced changes in the atmospheric wind forcing, i.e., quantities not directly observed by GRACE. Finally, the use of the developed Kalman-Filter approach as a destriping filter to remove artificial noise contaminating the GRACE observations is presented.

  14. Subsurface Ocean Climate Data Records: Global Ocean Heat and Freshwater Content

    NASA Astrophysics Data System (ADS)

    Boyer, T.; Locarnini, R. A.; Mishonov, A. V.; Reagan, J. R.

    2015-12-01

    The ocean is the main sink of excess heat in the Earth's climate system. It absorbs more than 90% of the Top of the Atmosphere imbalance between incoming solar radiation and outgoing long-wave radiation. The ocean, covering more than 70% of the Earth's surface, is also the major component of the planet's freshwater cycle. More than 60 years of in situ subsurface temperature and salinity data have been compiled and quality controlled in World Ocean Database of the National Centers for Environmental Information. These data have been used to calculate time series of global heat and salt changes in the ocean. Salt changes can be used to calculate freshwater changes, including from melting continental glaciers. Both time series provide a measure of the changes in the Earth's climate system: from heat sequestered in the ocean, to the rise of sea level due to thermosteric and halosteric components. The time series are updated every three months and are widely used in climate related studies. Method of quality control of the data, calculation of the time series, and dissemination and use of the time series are discussed.

  15. A Parallel Ocean Model With Adaptive Mesh Refinement Capability For Global Ocean Prediction

    SciTech Connect

    Herrnstein, A

    2005-09-08

    An ocean model with adaptive mesh refinement (AMR) capability is presented for simulating ocean circulation on decade time scales. The model closely resembles the LLNL ocean general circulation model with some components incorporated from other well known ocean models when appropriate. Spatial components are discretized using finite differences on a staggered grid where tracer and pressure variables are defined at cell centers and velocities at cell vertices (B-grid). Horizontal motion is modeled explicitly with leapfrog and Euler forward-backward time integration, and vertical motion is modeled semi-implicitly. New AMR strategies are presented for horizontal refinement on a B-grid, leapfrog time integration, and time integration of coupled systems with unequal time steps. These AMR capabilities are added to the LLNL software package SAMRAI (Structured Adaptive Mesh Refinement Application Infrastructure) and validated with standard benchmark tests. The ocean model is built on top of the amended SAMRAI library. The resulting model has the capability to dynamically increase resolution in localized areas of the domain. Limited basin tests are conducted using various refinement criteria and produce convergence trends in the model solution as refinement is increased. Carbon sequestration simulations are performed on decade time scales in domains the size of the North Atlantic and the global ocean. A suggestion is given for refinement criteria in such simulations. AMR predicts maximum pH changes and increases in CO{sub 2} concentration near the injection sites that are virtually unattainable with a uniform high resolution due to extremely long run times. Fine scale details near the injection sites are achieved by AMR with shorter run times than the finest uniform resolution tested despite the need for enhanced parallel performance. The North Atlantic simulations show a reduction in passive tracer errors when AMR is applied instead of a uniform coarse resolution. No

  16. The timescales of global surface-ocean connectivity

    PubMed Central

    Jönsson, Bror F.; Watson, James R.

    2016-01-01

    Planktonic communities are shaped through a balance of local evolutionary adaptation and ecological succession driven in large part by migration. The timescales over which these processes operate are still largely unresolved. Here we use Lagrangian particle tracking and network theory to quantify the timescale over which surface currents connect different regions of the global ocean. We find that the fastest path between two patches—each randomly located anywhere in the surface ocean—is, on average, less than a decade. These results suggest that marine planktonic communities may keep pace with climate change—increasing temperatures, ocean acidification and changes in stratification over decadal timescales—through the advection of resilient types. PMID:27093522

  17. A preliminary global oceanic cloud climatology from satellite albedo observations

    NASA Technical Reports Server (NTRS)

    Hughes, N. A.; Henderson-Sellers, A.

    1983-01-01

    A predictive relationship is developed between over-ocean cloud system albedo and the cloud amount present, using as a data base ERB satellite microwave readings at 0.5-0.7 micron and the USAF three-dimensional nephanalysis archive. The ERB data provided global coverage at a resolution of 2.5 x 2.5 deg during the 1974-78 period. Regression analyses were performed on the amounts and albedos for several years of data for one month in order to detect seasonal variations. A logarithmic relationship was found between the cloud system albedo and cloud amount over the oceans, with negligible seasonal variance. The analysis is noted to apply only where low surface albedos are encountered, and further work to extend the study to continental vegetated areas is indicated.

  18. Signature of ocean warming in global fisheries catch.

    PubMed

    Cheung, William W L; Watson, Reg; Pauly, Daniel

    2013-05-16

    Marine fishes and invertebrates respond to ocean warming through distribution shifts, generally to higher latitudes and deeper waters. Consequently, fisheries should be affected by 'tropicalization' of catch (increasing dominance of warm-water species). However, a signature of such climate-change effects on global fisheries catch has so far not been detected. Here we report such an index, the mean temperature of the catch (MTC), that is calculated from the average inferred temperature preference of exploited species weighted by their annual catch. Our results show that, after accounting for the effects of fishing and large-scale oceanographic variability, global MTC increased at a rate of 0.19 degrees Celsius per decade between 1970 and 2006, and non-tropical MTC increased at a rate of 0.23 degrees Celsius per decade. In tropical areas, MTC increased initially because of the reduction in the proportion of subtropical species catches, but subsequently stabilized as scope for further tropicalization of communities became limited. Changes in MTC in 52 large marine ecosystems, covering the majority of the world's coastal and shelf areas, are significantly and positively related to regional changes in sea surface temperature. This study shows that ocean warming has already affected global fisheries in the past four decades, highlighting the immediate need to develop adaptation plans to minimize the effect of such warming on the economy and food security of coastal communities, particularly in tropical regions. PMID:23676754

  19. Effects of Drake Passage on a strongly eddying global ocean

    NASA Astrophysics Data System (ADS)

    Viebahn, Jan; von der Heydt, Anna S.; Dijkstra, Henk A.

    2015-04-01

    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 ocean circulation due to critical gateway opening/deepening, changes in atmospheric CO2-concentration, and feedback mechanisms related to land-ice formation. Drake Passage (DP) is an intensively studied gateway because it plays a central role in closing the transport pathways of heat and chemicals in the ocean. The climate response to a closed DP has been explored with a variety of general circulation models, however, all of these models employ low model-grid resolutions such that the effects of subgrid-scale fluctuations ('eddies') are parameterized. We present results of the first high-resolution (0.1° horizontally) realistic global ocean model simulation with a closed DP in which the eddy field is largely resolved. The simulation extends over more than 200 years such that the strong transient adjustment process is passed and a near-equilibrium ocean state is reached. The effects of DP are diagnosed by comparing with both an open DP high-resolution control simulation (of same length) and corresponding low-resolution simulations. By focussing on the heat/tracer transports we demonstrate that the results are twofold: Considering spatially integrated transports the overall response to a closed DP is well captured by low-resolution simulations. However, looking at the actual spatial distributions drastic differences appear between far-scattered high-resolution and laminar-uniform low-resolution fields. We conclude that sparse and highly localized tracer proxy observations have to be interpreted carefully with the help of high-resolution model simulations.

  20. Global contamination by persistent organochlorines in the ocean

    SciTech Connect

    Iwata, H.; Tanabe, S.; Tatsukawa, R.

    1995-12-31

    Global pollution by persistent organochlorines (POCs) such as polychlorinated biphenyls (PCBs) and DDTs has become a matter of great concern in the public with an increase of recent scientific knowledge. Nevertheless, a world-wide survey has not been systematically carried out, which makes it difficult to clarify the dynamics and fate of POCs on a global scale. In this presentation, an attempt to monitor POCs in the world oceans will be introduced and the geographical distribution, composition, and temporal trend of POCs will be discussed on the basis of recent researches. This discussion led by the ocean surveys can be summarized as follows -- POCs not only DDTs but also PCBs, chlordane compounds and hexachlorocyclohexanes (HCHs) usage tended to shift or expand from the mid- to low-latitude areas during the last decades, the compounds released in the tropics were more efficiently dispersed rather than those in colder regions and then latitudinally redistributed, perhaps depending on their physico-chemical properties and climatic parameters. For example, it was found that HCHs transported through the atmosphere were prominently accumulated in higher latitude ocean, while DDTs are likely less-volatile and readily removed from the atmosphere even in the lower latitudes with high temperature. Furthermore, POCs in the sediment collected from the cold seas suggested that the aerial inputs into the seas were still continuing significantly, and the accumulation rates of OCs into sediments were smaller than the atmospheric inputs, indicating that the residues in water bodies were unlikely to decrease rapidly in near future. Although these schematic features have been conceptually presented from the field surveys, studies regarding the factors controlling POCs dynamics, the quantitative estimates to understand the fate, and the short-/longterm fluctuations particularly in open oceans are not adequate or still lacking.

  1. The global land and ocean mean energy balance

    NASA Astrophysics Data System (ADS)

    Wild, Martin; Folini, Doris

    2016-04-01

    land, and 16 and 100 Wm-2 over oceans, for sensible and latent heat fluxes, respectively. Estimated uncertainties are on the order of 10 and 5 Wm-2 for most surface and TOA fluxes, respectively. Combining these surface budgets with satellite-determined TOA budgets (CERES-EBAF) results in an atmospheric solar absorption of 77 and 82 Wm-2 and a net atmospheric thermal emission of -165 and -190 Wm-2 over land and oceans, respectively. We further revisit the global mean energy balance by combining the area weighed land and ocean mean budgets. This study is published in: Wild, M., Folini, D., Hakuba, M., Schär, C., Seneviratne, S.I., Kato, S., Rutan, D., Ammann, C., Wood, E.F., and König-Langlo, G., 2015: The energy balance over land and oceans: An assessment based on direct observations and CMIP5 climate models. Clim. Dyn., Dyn., 44, 3393-3429, doi: 10.1007/s00382-014-2430-z.

  2. Marine sources of bromoform in the global open ocean - global patterns and emissions

    NASA Astrophysics Data System (ADS)

    Stemmler, I.; Hense, I.; Quack, B.

    2014-11-01

    Bromoform (CHBr3) is one important precursor of atmospheric reactive bromine species that are involved in ozone depletion in the troposphere and stratosphere. In the open ocean bromoform production is linked to phytoplankton that contains the enzyme bromoperoxidase. Coastal sources of bromoform are higher than open ocean sources. However, open ocean emissions are important, because the transfer of tracers into higher altitude in the air, i.e. into the ozone layer, strongly depends on the location of emissions. For example, emissions in the tropics are more rapidly transported into the upper atmosphere than emissions from higher latitudes. Global spatio-temporal features of bromoform emissions are poorly constrained. Here, a global three-dimensional ocean biogeochemistry model (MPIOM-HAMOCC) is used to simulate bromoform cycling in the ocean and emissions into the atmosphere using recently published data of global atmospheric concentrations (Ziska et al., 2013) as upper boundary conditions. In general, simulated surface concentrations of CHBr3 match the observations well. Simulated global annual emissions based on monthly mean model output are lower than previous estimates, including the estimate by Ziska et al. (2013), because the gas-exchange reverses when less bromoform is produced in non-blooming seasons. This is the case for higher latitudes, i.e. the polar regions and northern North Atlantic. Further model experiments show that future model studies may need to distinguish different bromoform producing phytoplankton species and reveal that the transport of CHBr3 from the coast considerably alters open ocean bromoform concentrations, in particular in the northern sub-polar and polar regions.

  3. Marine sources of bromoform in the global open ocean - global patterns and emissions

    NASA Astrophysics Data System (ADS)

    Stemmler, I.; Hense, I.; Quack, B.

    2015-03-01

    Bromoform (CHBr3) is one important precursor of atmospheric reactive bromine species that are involved in ozone depletion in the troposphere and stratosphere. In the open ocean bromoform production is linked to phytoplankton that contains the enzyme bromoperoxidase. Coastal sources of bromoform are higher than open ocean sources. However, open ocean emissions are important because the transfer of tracers into higher altitude in the air, i.e. into the ozone layer, strongly depends on the location of emissions. For example, emissions in the tropics are more rapidly transported into the upper atmosphere than emissions from higher latitudes. Global spatio-temporal features of bromoform emissions are poorly constrained. Here, a global three-dimensional ocean biogeochemistry model (MPIOM-HAMOCC) is used to simulate bromoform cycling in the ocean and emissions into the atmosphere using recently published data of global atmospheric concentrations (Ziska et al., 2013) as upper boundary conditions. Our simulated surface concentrations of CHBr3 match the observations well. Simulated global annual emissions based on monthly mean model output are lower than previous estimates, including the estimate by Ziska et al. (2013), because the gas exchange reverses when less bromoform is produced in non-blooming seasons. This is the case for higher latitudes, i.e. the polar regions and northern North Atlantic. Further model experiments show that future model studies may need to distinguish different bromoform-producing phytoplankton species and reveal that the transport of CHBr3 from the coast considerably alters open ocean bromoform concentrations, in particular in the northern sub-polar and polar regions.

  4. Nonlinear Dependence of Global Warming Prediction on Ocean State

    NASA Astrophysics Data System (ADS)

    Liang, M.; Lin, L.; Tung, K. K.; Yung, Y. L.; Sun, S.

    2010-12-01

    Global temperature has increased by 0.8 C since the pre-industrial era, and is likely to increase further if greenhouse gas emission continues unchecked. Various mitigation efforts are being negotiated among nations to keep the increase under 2 C, beyond which the outcome is believed to be catastrophic. Such policy efforts are currently based on predictions by the state-of-the-art coupled atmosphere ocean models (AOGCM). Caution is advised for their use for the purpose of short-term (less than a century) climate prediction as the predicted warming and spatial patterns vary depending on the initial state of the ocean, even in an ensemble mean. The range of uncertainty in such predictions by Intergovernmental Panel on Climate Change (IPCC) models may be underreported when models were run with their oceans at various stages of adjustment with their atmospheres. By comparing a very long run (> 1000 years) of the coupled Goddard Institute for Space Studies (GISS) model with what was reported to IPCC Fourth Assessment Report (AR4), we show that the fully adjusted model transient climate sensitivity should be 30% higher for the same model, and the 2 C warming should occur sooner than previously predicted. Using model archives we further argue that this may be a common problem for the IPCC AR4 models, since few, if any, of the models has a fully adjusted ocean. For all models, multi-decadal climate predictions to 2050 are highly dependent on the initial ocean state (and so are unreliable). Such dependence cannot be removed simply by subtracting the climate drift from control runs.

  5. Ecological controls over global soil carbon storage

    SciTech Connect

    Schimel, D.S.

    1995-06-01

    Surface energy balance, runoff, and precipitation are sensitive not only to the kind and amount of vegetation present in a region but also to its physiological condition. Since the vegetation parameters that influence climate and hydrologic balance are also sensitive to it, it is critical to view vegetation, climate, and hydrology as an interactive system. Until recently, the study of effects of vegetation on climate was completely separate from its converse, the study of climate effects on vegetation. Progress on fully interactive climate/vegetation models is accelerating but still uneven, with largely separate efforts on ecosystem dynamics and physiology. Other key areas for future development in global climate/vegetation/hydrology models include improved nutrient cycling, links between climate and disturbance frequency, and strategies for validation.

  6. The Mercator-Ocean forecasting service: a 4D vision of the global ocean, serving the ocean services.

    NASA Astrophysics Data System (ADS)

    Hernandez, F.

    2006-12-01

    Mercator Ocean is a public consortium formed in Toulouse in early 2002 by the six major players in the French oceanography community: the space agency CNES, the scientific research centre CNRS, IFREMER (the institute of marine research and exploration), the development research institute IRD, the Meo France weather service, and SHOM (the French Navy's hydrography & oceanography department). In 1995, these same organizations gave themselves seven years to achieve a challenging objective: to conceive, develop and implement France's first operational oceanography system. The unique system would be capable of describing, analysing and predicting conditions at the ocean surface and subsurface in real time, anytime, anywhere in the world, even in the most inhospitable seas. That objective was met on 17 January 2001 with the release of the first Mercator ocean bulletin, providing a two-week forecast for the entire North Atlantic. More than three thousands new forecast charts are now added to the MERCATOR bulletin every week. Building on these successes, a dedicated operational oceanography team, Mercator Ocean, was set up in 2002. Mercator-Ocean's mission is to deliver incremental improvements in the service provided by this new operational oceanography capability by increasing the resolution and the geographic coverage of the models used. The current high-resolution model offers a 6 km grid resolution, and the first models offering global ocean coverage has been implemented early 2004. A ¼° model is operated since October 2005. The services offered by Mercator-Ocean consist in a real-time general description of the physical state of the ocean (3D currents, temperature, salinity ). This is exactly in line with the so called Marine Core Service initiative developed by the operational oceanography community within the programs funded by the European Commission and the European Space Agency (Marcoast, Mersea, BOSS4GMES projects ). The downstream activities are now in

  7. Global ocean circulation and equator-pole heat transport as a function of ocean GCM resolution

    SciTech Connect

    Covey, C.

    1994-06-01

    To determine whether resolution of smaller scales is necessary to simulate large-scale ocean climate correctly, I examine results from a global ocean GCM run with horizontal grid spacings spanning a range from coarse resolutions traditionally used in climate modeling to nearly the highest resolution attained with today`s computers. The experiments include four cases employing 4{degrees}, 2{degrees}, 1{degrees} and 1/2{degrees} spacing in latitude and longitude, which were run with minimal differences among them, i.e., in a controlled experiment. Two additional cases-1/2{degrees} spacing with a more scale-selective sub-gridscale mixing of heat and momentum, and approximate 1/4{degrees} spacing-are also included. The 1/4{degrees} run resolves most of the observed mesoscale eddy energy in the ocean. Several artificial constraints on the model tend to minimize differences among the different resolution cases. Nevertheless, for quantities of interest to global climate studies,the simulations show significant changes as resolution increases.

  8. Global ocean carbon uptake: magnitude, variability and trends

    NASA Astrophysics Data System (ADS)

    Wanninkhof, R.; Park, G.-H.; Takahashi, T.; Sweeney, C.; Feely, R.; Nojiri, Y.; Gruber, N.; Doney, S. C.; McKinley, G. A.; Lenton, A.; Le Quéré, C.; Heinze, C.; Schwinger, J.; Graven, H.; Khatiwala, S.

    2013-03-01

    The globally integrated sea-air anthropogenic carbon dioxide (CO2) flux from 1990 to 2009 is determined from models and data-based approaches as part of the Regional Carbon Cycle Assessment and Processes (RECCAP) project. Numerical methods include ocean inverse models, atmospheric inverse models, and ocean general circulation models with parameterized biogeochemistry (OBGCMs). The median value of different approaches shows good agreement in average uptake. The best estimate of anthropogenic CO2 uptake for the time period based on a compilation of approaches is -2.0 Pg C yr-1. The interannual variability in the sea-air flux is largely driven by large-scale climate re-organizations and is estimated at 0.2 Pg C yr-1 for the two decades with some systematic differences between approaches. The largest differences between approaches are seen in the decadal trends. The trends range from -0.13 (Pg C yr-1) decade-1 to -0.50 (Pg C yr-1) decade-1 for the two decades under investigation. The OBGCMs and the data-based sea-air CO2 flux estimates show appreciably smaller decadal trends than estimates based on changes in carbon inventory suggesting that methods capable of resolving shorter timescales are showing a slowing of the rate of ocean CO2 uptake. RECCAP model outputs for five decades show similar differences in trends between approaches.

  9. Global atmospheric and ocean modeling on the connection machine

    SciTech Connect

    Atlas, S.R.

    1993-12-01

    This paper describes the high-level architecture of two parallel global climate models: an atmospheric model based on the Geophysical Fluid Dynamics Laboratory (GFDL) SKYHI model, and an ocean model descended from the Bryan-Cox-Semtner ocean general circulation model. These parallel models are being developed as part of a long-term research collaboration between Los Alamos National Laboratory (LANL) and the GFDL. The goal of this collaboration is to develop parallel global climate models which are modular in structure, portable across a wide variety of machine architectures and programming paradigms, and provide an appropriate starting point for a fully coupled model. Several design considerations have emerged as central to achieving these goals. These include the expression of the models in terms of mathematical primitives such as stencil operators, to facilitate performance optimization on different computational platforms; the isolation of communication from computation to allow flexible implementation of a single code under message-passing or data parallel programming paradigms; and judicious memory management to achieve modularity without memory explosion costs.

  10. Global abundance of planktonic heterotrophic protists in the deep ocean.

    PubMed

    Pernice, Massimo C; Forn, Irene; Gomes, Ana; Lara, Elena; Alonso-Sáez, Laura; Arrieta, Jesus M; del Carmen Garcia, Francisca; Hernando-Morales, Victor; MacKenzie, Roy; Mestre, Mireia; Sintes, Eva; Teira, Eva; Valencia, Joaquin; Varela, Marta M; Vaqué, Dolors; Duarte, Carlos M; Gasol, Josep M; Massana, Ramon

    2015-03-01

    The dark ocean is one of the largest biomes on Earth, with critical roles in organic matter remineralization and global carbon sequestration. Despite its recognized importance, little is known about some key microbial players, such as the community of heterotrophic protists (HP), which are likely the main consumers of prokaryotic biomass. To investigate this microbial component at a global scale, we determined their abundance and biomass in deepwater column samples from the Malaspina 2010 circumnavigation using a combination of epifluorescence microscopy and flow cytometry. HP were ubiquitously found at all depths investigated down to 4000 m. HP abundances decreased with depth, from an average of 72±19 cells ml(-1) in mesopelagic waters down to 11±1 cells ml(-1) in bathypelagic waters, whereas their total biomass decreased from 280±46 to 50±14 pg C ml(-1). The parameters that better explained the variance of HP abundance were depth and prokaryote abundance, and to lesser extent oxygen concentration. The generally good correlation with prokaryotic abundance suggested active grazing of HP on prokaryotes. On a finer scale, the prokaryote:HP abundance ratio varied at a regional scale, and sites with the highest ratios exhibited a larger contribution of fungi molecular signal. Our study is a step forward towards determining the relationship between HP and their environment, unveiling their importance as players in the dark ocean's microbial food web. PMID:25290506

  11. Freshwater and heat transports from global ocean synthesis

    NASA Astrophysics Data System (ADS)

    Valdivieso, M.; Haines, K.; Zuo, H.; Lea, D.

    2014-01-01

    An eddy-permitting ¼° global ocean reanalysis based on the Operational Met Office FOAM data assimilation system has been run for 1989-2010 forced by ERA-Interim meteorology. Freshwater and heat transports are compared with published estimates globally and in each basin, with special focus on the Atlantic. The meridional transports agree with observations within errors at most locations, but where eddies are active the transports by the mean flow are nearly always in better agreement than the total transports. Eddy transports are down gradient and are enhanced relative to a free run. They may oppose or reinforce mean transports and provide 40-50% of the total transport near midlatitude fronts, where eddies with time scales <1 month provide up to 15%. Basin-scale freshwater convergences are calculated with the Arctic/Atlantic, Indian, and Pacific oceans north of 32°S, all implying net evaporation of 0.33 ± 0.04 Sv, 0.65 ± 0.07 Sv, and 0.09 ± 0.04 Sv, respectively, within the uncertainty of observations in the Atlantic and Pacific. The Indian is more evaporative and the Southern Ocean has more precipitation (1.07 Sv). Air-sea fluxes are modified by assimilation influencing turbulent heat fluxes and evaporation. Generally, surface and assimilation fluxes together match the meridional transports, indicating that the reanalysis is close to a steady state. Atlantic overturning and gyre transports are assessed with overturning freshwater transports southward at all latitudes. At 26°N eddy transports are negligible, overturning transport is 0.67 ± 0.19 Sv southward and gyre transport is 0.44 ± 0.17 Sv northward, with divergence between 26°N and the Bering Strait of 0.13 ± 0.23 Sv over 2004-2010.

  12. Paradox lost: silicon 32 and the global ocean silica cycle

    NASA Astrophysics Data System (ADS)

    Craig, H.; Somayajulu, B. L. K.; Turekian, K. K.

    2000-02-01

    The 32Si Paradox is that the GEOSECS measurements of 32Si specific activity in silica collected on ferric hydroxide-coated fibers are essentially uniform throughout the deep water of the global oceans [Somayajulu et al., Earth Planet. Sci. Lett. 85 (1987) 329-342; 107 (1991) 197-216]. Peng, Maier-Reimer, and Broecker have argued that 32Si specific activities in Indian and Pacific deep water should be 3-5 times lower than in the deep Atlantic, because the dissolved SiO 2 concentrations are higher than in the Atlantic by this factor, and because cosmogenic 32Si should be essentially confined to the ocean basins in which it falls due to its short half-life relative to mixing times for water interchange between the oceans. Thus these authors proposed that the entire GEOSECS 32Si data set "may be flawed". The resolution of the 32Si Paradox is straightforward. Silica collected on the acrilan fibers is a two-phase mixture of biogenic particulate SiO 2 (opaline tests of diatoms and radiolaria) and silica scavenged chemically from dissolved SiO 2 in ocean water. Particulate silica is the high-activity component in this mixture, and dissolved SiO 2 is the low-activity end-member. Thus the mixing trajectories on 'Cornucopia plots' of specific activity vs. reciprocal SiO 2 recovered weights overlap in specific-activity range, regardless of the different concentrations and specific activities of dissolved silica in the deep waters. The specific activities of dissolved SiO 2 in the Pacific, Indian, and Atlantic oceans, as deciphered from the two-component total activity data, are ˜0, 2.6, and 4.5 dpm/kg SiO 2. The atmospheric production rate of 32Si has been calculated and is found to be 0.72 atoms/m 2 s. This value is much lower than in previous calculations, which were based on the Lal and Peters plots of stratospheric fallout that incorrectly use geomagnetic latitude for scaling the fallout patterns. Correcting these curves to scale by geographic latitude, which controls the

  13. Madden Julian Oscillation impacts on global ocean surface waves

    NASA Astrophysics Data System (ADS)

    Marshall, Andrew G.; Hendon, Harry H.; Durrant, Tom H.; Hemer, Mark A.

    2015-12-01

    We assess the impact of the tropical Madden Julian Oscillation (MJO) on global ocean wind waves using 30 years of wave data from a wave model hindcast that is forced with high resolution surface winds from the NCEP-CFSR reanalysis. We concentrate on the boreal winter season when the MJO has its greatest amplitude and is potentially a source of predictable wave impacts at intra-seasonal lead times. Statistically significant anomalies in significant wave height (Hs), peak wave period (Tp) and zonal wave energy flux (CgE) are found to covary with the intra-seasonal variation of surface zonal wind induced by the MJO as it traverses eastward from the western tropical Indian Ocean to the eastern tropical Pacific. Tp varies generally out of phase with Hs over the life cycle of the MJO, indicating that these MJO-wave anomalies are locally wind-generated rather than remotely generated by ocean swell. Pronounced Hs anomalies develop on the northwest shelf of Australia, where the MJO is known to influence sea level and surface temperatures, and in the western Caribbean Sea and Guatemalan-Panama Seas with enhanced wave anomalies apparent in the vicinity of the Tehuantepec and Papagayo gaps. Significant wave anomalies are also detected in the North Pacific and North Atlantic oceans in connection with the MJO teleconnection to the extratropics via atmospheric wave propagation. The impact in the north Atlantic stems from induction of the high phase of the North Atlantic Oscillation (NAO) about 1 week after MJO convection traverses the Indian Ocean, and the low phase of the NAO about one week after suppressed convection traverses the Indian Ocean. Strong positive Hs anomalies maximize on the Northern European coast in the positive NAO phase and vice versa for the negative NAO phase. The MJO also influences the occurrence of daily low (below the 5th percentile) and high (above the 95th percentile) wave conditions across the tropics and in the North Pacific and North Atlantic

  14. Beyond peak water storage? A global estimate of declining water storage in reservoirs and snow packs

    NASA Astrophysics Data System (ADS)

    Wisser, D.; Frolking, S.; Wada, Y.; Bierkens, M. F.

    2012-12-01

    Water storage is one of the primary mechanisms for coping with increasing variability of water supply and demand that can be expected with growing population and a changing climate. Man-made reservoirs can currently store about 15% of the global annual runoff. A similar amount of water is stored in one of the most important natural storage components - seasonal snow packs. The amount of water stored in each of those man-made and natural systems is roughly equivalent to the total annual anthropogenic water withdrawals. Storage in seasonal snow packs is declining as a result of climate-driven changes in snowfall and snowmelt. At the same time, reservoir storage is declining as a result of sedimentation and limited construction of new reservoirs. We use a global hydrological model, combined with a global data set of ~6000 large reservoirs to simulate changes in reservoir and snow pack water storage and analyze impacts of those changes on seasonal water availability using a set of scenarios for changing climate conditions. Reservoir sedimentation is simulated using global erosion and sedimentation data sets and validated with observed reservoir storage loss. Results indicate annual loss rates between 0.5 and 1.0% of the installed capacity for most reservoirs, outpacing the storage increases through the construction of new reservoirs for the last decades so that reservoir storage is declining globally. With most reservoirs being about 50 years old, these losses threaten the sustainability of reservoir operation and can pose significant challenges to water resources management. Similarly, seasonal snow storage is declining at about 0.5% per year for the last 20 years. Even without changes in the magnitude of total precipitation, there can be significant changes in basin hydrology if there are climate-driven changes in snowfall and snowmelt, potentially away from the period (summer) when demand for irrigation, water supply, or hydropower production is high. These shifts

  15. Geological storage of CO2 within the oceanic crust by gravitational trapping

    NASA Astrophysics Data System (ADS)

    Marieni, Chiara; Henstock, Timothy J.; Teagle, Damon A. H.

    2013-12-01

    rise of atmospheric carbon dioxide (CO2) principally due to the burning of fossil fuels is a key driver of anthropogenic climate change. Mitigation strategies include improved efficiency, using renewable energy, and capture and long-term sequestration of CO2. Most sequestration research considers CO2 injection into deep saline aquifers or depleted hydrocarbon reservoirs. Unconventional suggestions include CO2 storage in the porous volcanic lavas of uppermost oceanic crust. Here we test the feasibility of injecting CO2 into deep-sea basalts and identify sites where CO2 should be both physically and gravitationally trapped. We use global databases to estimate pressure and temperature, hence density of CO2 and seawater at the sediment-basement interface. At previously suggested sites on the Juan de Fuca Plate and in the eastern equatorial Pacific Ocean, CO2 is gravitationally unstable. However, we identify five sediment-covered regions where CO2 is denser than seawater, each sufficient for several centuries of anthropogenic CO2 emissions.

  16. Global and regional ocean carbon uptake and climate change: sensitivity to a substantial mitigation scenario

    NASA Astrophysics Data System (ADS)

    Vichi, Marcello; Manzini, Elisa; Fogli, Pier Giuseppe; Alessandri, Andrea; Patara, Lavinia; Scoccimarro, Enrico; Masina, Simona; Navarra, Antonio

    2011-11-01

    Under future scenarios of business-as-usual emissions, the ocean storage of anthropogenic carbon is anticipated to decrease because of ocean chemistry constraints and positive feedbacks in the carbon-climate dynamics, whereas it is still unknown how the oceanic carbon cycle will respond to more substantial mitigation scenarios. To evaluate the natural system response to prescribed atmospheric "target" concentrations and assess the response of the ocean carbon pool to these values, 2 centennial projection simulations have been performed with an Earth System Model that includes a fully coupled carbon cycle, forced in one case with a mitigation scenario and the other with the SRES A1B scenario. End of century ocean uptake with the mitigation scenario is projected to return to the same magnitude of carbon fluxes as simulated in 1960 in the Pacific Ocean and to lower values in the Atlantic. With A1B, the major ocean basins are instead projected to decrease the capacity for carbon uptake globally as found with simpler carbon cycle models, while at the regional level the response is contrasting. The model indicates that the equatorial Pacific may increase the carbon uptake rates in both scenarios, owing to enhancement of the biological carbon pump evidenced by an increase in Net Community Production (NCP) following changes in the subsurface equatorial circulation and enhanced iron availability from extratropical regions. NCP is a proxy of the bulk organic carbon made available to the higher trophic levels and potentially exportable from the surface layers. The model results indicate that, besides the localized increase in the equatorial Pacific, the NCP of lower trophic levels in the northern Pacific and Atlantic oceans is projected to be halved with respect to the current climate under a substantial mitigation scenario at the end of the twenty-first century. It is thus suggested that changes due to cumulative carbon emissions up to present and the projected concentration

  17. Assimilation of SeaWiFS Ocean Chlorophyll Data into a Three-Dimensional Global Ocean Model

    NASA Technical Reports Server (NTRS)

    Gregg, Watson W.

    2005-01-01

    Assimilation of satellite ocean color data is a relatively new phenomenon in ocean sciences. However, with routine observations from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), launched in late 1997, and now with new data from the Moderate Resolution Imaging Spectroradometer (MODIS) Aqua, there is increasing interest in ocean color data assimilation. Here SeaWiFS chlorophyll data were assimilated with an established thre-dimentional global ocean model. The assimilation improved estimates of hlorophyll and primary production relative to a free-run (no assimilation) model. This represents the first attempt at ocean color data assimilation using NASA satellites in a global model. The results suggest the potential of assimilation of satellite ocean chlorophyll data for improving models.

  18. Designing Scatterometer Constellations for Sampling Global Ocean Vector Winds

    NASA Astrophysics Data System (ADS)

    Rodriguez, E.; Chelton, D. B.; Stoffelen, A.; Schlax, M.

    2012-12-01

    The rapid temporal variations in ocean vector winds make it impossible to obtain synoptic global snapshots of winds and wind stress from a single spaceborne sensor. Even when multiple sensors are present, the peculiarities of the resulting space-time sampling pattern require that significant smoothing in space and time be performed to limit spatially and temporally inhomogeneous error characteristics in the merged data. Based on the collected common experience in its member states, the World Meteorological Organization collects requirements for spatio-temporal sampling in meteorological applications such as global and regional Numerical Weather Prediction, nowcasting, and climate. An additional concern, when constructing data sets from sun-synchronous missions, is that undersampling of diurnal and sub-diurnal variability may result in aliasing of the climate data record. Indeed, examination of climatologies constructed from different satellite missions, such as NASA's QuikSCAT and EUMETSAT's ASCAT scatterometers, show systematic differences that cannot be explained as being due solely to unresolved incoherent diurnal and sub-diurnal variability. Some of these differences, especially in the tropics, are probably explained by systematic diurnal and sub-diurnal variations. Other differences may be due to the difficulty of cross-calibrating sun-synchronous satellites with different local times. Forthcoming satellite missions may offer the possibility of overcoming or mitigating the space-time sampling and calibration challenges using multiple coordinated platforms. In the next decade, there is an expectation that ocean vector winds will be measured simultaneously by multiple satellites from the European community, India, China, and the United States. The coordination and suitable merging of the data from these satellites to produce a climate data record will be a challenge to the ocean vector winds community. In this presentation, we use climatologies constructed from

  19. Modeling selective pressures on phytoplankton in the global ocean.

    PubMed

    Bragg, Jason G; Dutkiewicz, Stephanie; Jahn, Oliver; Follows, Michael J; Chisholm, Sallie W

    2010-01-01

    Our view of marine microbes is transforming, as culture-independent methods facilitate rapid characterization of microbial diversity. It is difficult to assimilate this information into our understanding of marine microbe ecology and evolution, because their distributions, traits, and genomes are shaped by forces that are complex and dynamic. Here we incorporate diverse forces--physical, biogeochemical, ecological, and mutational--into a global ocean model to study selective pressures on a simple trait in a widely distributed lineage of picophytoplankton: the nitrogen use abilities of Synechococcus and Prochlorococcus cyanobacteria. Some Prochlorococcus ecotypes have lost the ability to use nitrate, whereas their close relatives, marine Synechococcus, typically retain it. We impose mutations for the loss of nitrogen use abilities in modeled picophytoplankton, and ask: in which parts of the ocean are mutants most disadvantaged by losing the ability to use nitrate, and in which parts are they least disadvantaged? Our model predicts that this selective disadvantage is smallest for picophytoplankton that live in tropical regions where Prochlorococcus are abundant in the real ocean. Conversely, the selective disadvantage of losing the ability to use nitrate is larger for modeled picophytoplankton that live at higher latitudes, where Synechococcus are abundant. In regions where we expect Prochlorococcus and Synechococcus populations to cycle seasonally in the real ocean, we find that model ecotypes with seasonal population dynamics similar to Prochlorococcus are less disadvantaged by losing the ability to use nitrate than model ecotypes with seasonal population dynamics similar to Synechococcus. The model predictions for the selective advantage associated with nitrate use are broadly consistent with the distribution of this ability among marine picocyanobacteria, and at finer scales, can provide insights into interactions between temporally varying ocean processes and

  20. Does Ocean Color Data Assimilation Improve Estimates of Global Ocean Inorganic Carbon?

    NASA Technical Reports Server (NTRS)

    Gregg, Watson

    2012-01-01

    Ocean color data assimilation has been shown to dramatically improve chlorophyll abundances and distributions globally and regionally in the oceans. Chlorophyll is a proxy for phytoplankton biomass (which is explicitly defined in a model), and is related to the inorganic carbon cycle through the interactions of the organic carbon (particulate and dissolved) and through primary production where inorganic carbon is directly taken out of the system. Does ocean color data assimilation, whose effects on estimates of chlorophyll are demonstrable, trickle through the simulated ocean carbon system to produce improved estimates of inorganic carbon? Our emphasis here is dissolved inorganic carbon, pC02, and the air-sea flux. We use a sequential data assimilation method that assimilates chlorophyll directly and indirectly changes nutrient concentrations in a multi-variate approach. The results are decidedly mixed. Dissolved organic carbon estimates from the assimilation model are not meaningfully different from free-run, or unassimilated results, and comparisons with in situ data are similar. pC02 estimates are generally worse after data assimilation, with global estimates diverging 6.4% from in situ data, while free-run estimates are only 4.7% higher. Basin correlations are, however, slightly improved: r increase from 0.78 to 0.79, and slope closer to unity at 0.94 compared to 0.86. In contrast, air-sea flux of C02 is noticeably improved after data assimilation. Global differences decline from -0.635 mol/m2/y (stronger model sink from the atmosphere) to -0.202 mol/m2/y. Basin correlations are slightly improved from r=O.77 to r=0.78, with slope closer to unity (from 0.93 to 0.99). The Equatorial Atlantic appears as a slight sink in the free-run, but is correctly represented as a moderate source in the assimilation model. However, the assimilation model shows the Antarctic to be a source, rather than a modest sink and the North Indian basin is represented incorrectly as a sink

  1. Approach to equilibrium in accelerated global oceanic models

    SciTech Connect

    Danabasoglu, G.; McWilliams, J.C.; Large, W.G.

    1996-05-01

    The approach to equilibrium of a coarse-resolution, seasonally forced, global oceanic general circulation model is investigated, considering the effects of a widely used acceleration technique that distorts the dynamics by using unequal time steps in the governing equations. A measure of the equilibration time for any solution property is defined as the time it takes to go 90% of the way from its present value to its equilibrium value. This measure becomes approximately time invariant only after sufficiently long integration. It indicates that the total kinetic energy and most mass transport rates attain equilibrium within about 90 and 40 calendar years, respectively. The upper-ocean potential temperature and salinity equilibrium times are about 480 and 380 calender years, following 150- and 20-year initial adjustments, respectively. In the abyssal ocean, potential temperature and salinity equilibration take about 4500 and 3900 calender years, respectively. These longer equilibration times are due to the slow diffusion of tracers both along and across the isopycnal surfaces in stably stratified regions, and these times vary with the associated diffusivities. An analysis of synchronous (i.e., not accelerated) integrations shows that there is a complex interplay between convective, advective, and diffusive timescales. Because of the distortion by acceleration of the seasonal cycle, the solutions display some significant adjustments upon switching to synchronous integration. However, the proper seasonal cycle is recovered within five years. Provided that a sufficient equilibrium state has been achieved with acceleration, the model must be integrated synchronously for only about 15 years thereafter to closely approach synchronous equilibrium. 16 refs., 11 figs., 1 tab.

  2. Role of the Polar Oceans in Global Climate

    NASA Technical Reports Server (NTRS)

    Rothrock, D. A.

    2003-01-01

    The project focused on ice-ocean model development and in particular on the assimilation of ice motion data and ice concentration data into both regional and global models. Many of the resulting publications below deal with improvements made in the physics treated by the model and the procedures for assimilating data. Several papers examine how the ability of the model to simulate the past behavior of the ice cover, especially to represent the ice thickness and ice deformation, is improved by data assimilation. A second aspect of the work involved interpretation of modeled behavior. Resulting papers treat the decline of arctic ice thickness over the last thirty years, and how that decline was caused by a slight warming of the near-surface atmosphere, and also how large variation in ice thickness are due to changes in wind patterns associated with a well- known oscillation of the atmospheric circulation. The research resulted in over 20 published papers on these topics.

  3. Wet deposition of persistent organic pollutants to the global oceans.

    PubMed

    Jurado, Elena; Jaward, Foday; Lohmann, Rainer; Jones, Kevin C; Simó, Rafel; Dachs, Jordi

    2005-04-15

    Wet deposition fluxes of polychlorinated biphenyls and polychlorinated dibenzo-p-dioxins and furans to the Atlantic Ocean have been estimated by combining meteorological satellite data and measured atmospheric field concentrations. They are then compared to other atmospheric depositional mechanisms on a global scale. Additional features not treated in traditional studies are addressed such as contaminant adsorption onto raindrops and enhancement of dry gaseous diffusive fluxes due to rain-induced turbulence. Wet deposition estimates show a high spatial and seasonal variability, with maxima located in the Intertropical Convergence Zone (ITCZ) and in low-temperature regions. Seasonal variability reflects the northward shift of ITCZ in July. Average wet deposition fluxes estimated for the Atlantic Ocean in this study are 110 and 45 ng m(-2) yr(-1) for sigmaPCB and sigmaPCDD/Fs, respectively. Furthermore, the total wet deposition to the Atlantic results in 4100 kg yr(-1) (sigmaPCB) and 2500 kg yr(-1) (sigmaPCDD/Fs). Model validation shows good agreement with available coastal data measurements of wet deposition fluxes. When compared to other atmospheric depositional mechanisms and during precipitation events, wet deposition is found to be dominant. However, when raining events and non-raining time periods are integrated, air-water diffusive exchange fluxes acquire an important role, which can be dominant in some regions and for some POPs. PMID:15884331

  4. Effects of Drake Passage on a strongly eddying global ocean

    NASA Astrophysics Data System (ADS)

    Viebahn, Jan P.; Heydt, Anna S.; Le Bars, Dewi; Dijkstra, Henk A.

    2016-05-01

    The climate impact of ocean gateway openings during the Eocene-Oligocene transition is still under debate. Previous model studies employed grid resolutions at which the impact of mesoscale eddies has to be parameterized. We present results of a state-of-the-art eddy-resolving global ocean model with a closed Drake Passage and compare with results of the same model at noneddying resolution. An analysis of the pathways of heat by decomposing the meridional heat transport into eddy, horizontal, and overturning circulation components indicates that the model behavior on the large scale is qualitatively similar at both resolutions. Closing Drake Passage induces (i) sea surface warming around Antarctica due to equatorward expansion of the subpolar gyres, (ii) the collapse of the overturning circulation related to North Atlantic Deep Water formation leading to surface cooling in the North Atlantic, and (iii) significant equatorward eddy heat transport near Antarctica. However, quantitative details significantly depend on the chosen resolution. The warming around Antarctica is substantially larger for the noneddying configuration (˜5.5°C) than for the eddying configuration (˜2.5°C). This is a consequence of the subpolar mean flow which partitions differently into gyres and circumpolar current at different resolutions. We conclude that for a deciphering of the different mechanisms active in Eocene-Oligocene climate change detailed analyses of the pathways of heat in the different climate subsystems are crucial in order to clearly identify the physical processes actually at work.

  5. Simulating the global distribution of nitrogen isotopes in the ocean

    NASA Astrophysics Data System (ADS)

    Somes, Christopher J.; Schmittner, Andreas; Galbraith, Eric D.; Lehmann, Moritz F.; Altabet, Mark A.; Montoya, Joseph P.; Letelier, Ricardo M.; Mix, Alan C.; Bourbonnais, Annie; Eby, Michael

    2010-12-01

    We present a new nitrogen isotope model incorporated into the three-dimensional ocean component of a global Earth system climate model designed for millennial timescale simulations. The model includes prognostic tracers for the two stable nitrogen isotopes, 14N and 15N, in the nitrate (NO3-), phytoplankton, zooplankton, and detritus variables of the marine ecosystem model. The isotope effects of algal NO3- uptake, nitrogen fixation, water column denitrification, and zooplankton excretion are considered as well as the removal of NO3- by sedimentary denitrification. A global database of δ15NO3- observations is compiled from previous studies and compared to the model results on a regional basis where sufficient observations exist. The model is able to qualitatively and quantitatively reproduce many of the observed patterns such as high subsurface values in water column denitrification zones and the meridional and vertical gradients in the Southern Ocean. The observed pronounced subsurface minimum in the Atlantic is underestimated by the model presumably owing to too little simulated nitrogen fixation there. Sensitivity experiments reveal that algal NO3- uptake, nitrogen fixation, and water column denitrification have the strongest effects on the simulated distribution of nitrogen isotopes, whereas the effect from zooplankton excretion is weaker. Both water column and sedimentary denitrification also have important indirect effects on the nitrogen isotope distribution by reducing the fixed nitrogen inventory, which creates an ecological niche for nitrogen fixers and, thus, stimulates additional N2 fixation in the model. Important model deficiencies are identified, and strategies for future improvement and possibilities for model application are outlined.

  6. Multidecadal climate variability of global lands and oceans

    USGS Publications Warehouse

    McCabe, G.J.; Palecki, M.A.

    2006-01-01

    Principal components analysis (PCA) and singular value decomposition (SVD) are used to identify the primary modes of decadal and multidecadal variability in annual global Palmer Drought Severity Index (PDSI) values and sea-surface temperature (SSTs). The PDSI and SST data for 1925-2003 were detrended and smoothed (with a 10-year moving average) to isolate the decadal and multidecadal variability. The first two principal components (PCs) of the PDSI PCA explained almost 38% of the decadal and multidecadal variance in the detrended and smoothed global annual PDSI data. The first two PCs of detrended and smoothed global annual SSTs explained nearly 56% of the decadal variability in global SSTs. The PDSI PCs and the SST PCs are directly correlated in a pairwise fashion. The first PDSI and SST PCs reflect variability of the detrended and smoothed annual Pacific Decadal Oscillation (PDO), as well as detrended and smoothed annual Indian Ocean SSTs. The second set of PCs is strongly associated with the Atlantic Multidecadal Oscillation (AMO). The SVD analysis of the cross-covariance of the PDSI and SST data confirmed the close link between the PDSI and SST modes of decadal and multidecadal variation and provided a verification of the PCA results. These findings indicate that the major modes of multidecadal variations in SSTs and land-surface climate conditions are highly interrelated through a small number of spatially complex but slowly varying teleconnections. Therefore, these relations may be adaptable to providing improved baseline conditions for seasonal climate forecasting. Published in 2006 by John Wiley & Sons, Ltd.

  7. GLOBEC: Global Ocean Ecosystems Dynamics: A component of the US Global Change Research Program

    NASA Technical Reports Server (NTRS)

    1991-01-01

    GLOBEC (GLOBal ocean ECosystems dynamics) is a research initiative proposed by the oceanographic and fisheries communities to address the question of how changes in global environment are expected to affect the abundance and production of animals in the sea. The approach to this problem is to develop a fundamental understanding of the mechanisms that determine both the abundance of key marine animal populations and their variances in space and time. The assumption is that the physical environment is a major contributor to patterns of abundance and production of marine animals, in large part because the planktonic life stages typical of most marine animals are intrinsically at the mercy of the fluid motions of the medium in which they live. Consequently, the authors reason that a logical approach to predicting the potential impact of a globally changing environment is to understand how the physical environment, both directly and indirectly, contributes to animal abundance and its variability in marine ecosystems. The plans for this coordinated study of of the potential impact of global change on ocean ecosystems dynamics are discussed.

  8. Global ocean carbon uptake: magnitude, variability and trends

    NASA Astrophysics Data System (ADS)

    Wanninkhof, R.; Park, G.-H.; Takahashi, T.; Sweeney, C.; Feely, R.; Nojiri, Y.; Gruber, N.; Doney, S. C.; McKinley, G. A.; Lenton, A.; Le Quéré, C.; Heinze, C.; Schwinger, J.; Graven, H.; Khatiwala, S.

    2012-08-01

    Estimates of the anthropogenic global-integrated sea-air carbon dioxide (CO2) flux from 1990 to 2009, based on different models and measurements, range from -1.4 to -2.6 Pg C yr-1. The median values of anthropogenic CO2 for each method show better agreement and are: -1.9 for Pg C yr-1 for numerical ocean general circulation hind cast models (OGCMs) with parameterized biogeochemistry; -2.1 Pg C yr-1 for atmospheric inverse models; -1.9 Pg C yr-1 for global atmospheric constraints based on O2 / N2 ratios for 1990-2000; and -2.4 Pg C yr-1 for oceanic inverse models. An updated estimate of this anthropogenic CO2 flux based on a climatology of sea-air partial pressure of CO2 differences (ΔpCO2) (Takahashi et al., 2009) and a bulk formulation of gas transfer with wind speed for year 2000 is -2.0 Pg C yr-1. Using this ΔpCO2 climatology and empirical relationships of pCO2 with sea-surface temperature (SST) anomalies (Park et al., 2010a), the interannual variability of the contemporary CO2 flux is estimated to be 0.20 Pg C yr-1 (1σ) from 1990 through 2009. This is similar to the variability estimated by the OGCMs of 0.16 Pg C yr-1 but smaller than the interannual variability from atmospheric inverse estimates of 0.40 Pg C yr-1. The variability is largely driven by large-scale climate re-organizations. The decadal trends for different methods range from -0.13 (Pg C yr-1) decade-1 to -0.50 (Pg C yr-1) decade-1. The OGCMs and the data based sea-air CO2 flux estimates show smaller uptakes and appreciably smaller decadal trends than estimates based on changes in carbon inventory suggesting that methods capable of resolving shorter timescales are showing a slowing of the rate of ocean CO2 uptake. It is not clear if this large difference in trend is a methodological issue or a real natural feedback.

  9. Iron Resources and Oceanic Nutrients: Advancement of Global Environment Simulations

    NASA Astrophysics Data System (ADS)

    Debaar, H. J.

    2002-12-01

    The concept of a single factor limiting plankton blooms, is presently giving way to co-limitation by light, and the nutrients N, P, Si and Fe. Primary production, export into the deep sea, and CO2 uptake from the atmosphere together form the 'biological pump' in Ocean Biogeochemical Climate Models (OBCM's). Thus far OBCM's assume just one limiting nutrient (P) and one universal phytoplankton species, for C budgets and CO2 exchange. New realistic OBCM's are being developed for budgeting and exchanges of both CO2 and DMS, implementing (i) co-limitation by 4 nutrients of 5 major taxonomic classes of phytoplankton, (ii) DMS(P) pathways, (iii) global iron cycling, (iv) chemical forms of iron and (v) iron supply into surface waters. The new OBCM's will predict realistic climate scenario's, notably climatic feedbacks on oceanic biogeochemistry. IRONAGES is a European consortium of twelve institutes and is coordinated by Royal NIOZ. Input from below of iron from anoxic sediments of coastal margins has been assessed (March 2002) along a 2-D vertical section from Europe into the centre of the north Atlantic. Input from above of Fe(II) dissolved in rainwater from Sahara dust blown over the central Atlantic will be quantified at sea (October 2002), and related to observed plankton production. Different chemical forms of iron are being assessed and a certification excercise for Fe in seawater also under aegis of SCOR Working Group 109 is being completed (December 2002). For two major DMS-producing algal groups Phaeocystis sp. and Emiliania huxleyi the life cycle, Fe limitation, export production, CO2 uptake and DMS emissions have been synthesized from existing literature and laboratory experiments. This is being fed into ecosystem modeling, as well as into DMS(P) pathway modeling. Also know-how has been synthesized for three other major classes (diatoms, N2-fixing Trichodesmium and nano-pico-plankton) and fed into the ecosystem modeling. Pathways of DMS(P) in blooms are being

  10. Ocean topography mapping, improvement of the marine geoid, and global permanent ocean circulation studies from TOPEX/Poseidon altimeter data

    NASA Technical Reports Server (NTRS)

    Marsh, James G.; Lerch, F. J.; Koblinsky, C. J.; Nerem, R. S.; Klosko, S. M.; Williamson, R. G.

    1991-01-01

    The TOPEX/POSEIDON altimeter measurements will be the first global observations of the sea surface with accuracy sufficient to make quantitative determinations of the ocean's general circulation and its variations. These measurements are an important step to understanding global change in the ocean and its impact on the climate. Our investigation will focus on the examination of features in the sea surface elevation at the largest spatial and temporal scales. TOPEX/POSEIDON altimeter measurements will be used in conjunction with observations from past satellite-altimeter missions, such as NASA's GEOS-3 and Seasat, the U.S. Navy's Geosat and SALT, and the European Remote Sensing satellite in order to address the following issues: (1) Improve models of the marine geoid, especially at wavelengths needed to understand the basin-scale ocean dynamic topograpy. (2) Measure directly from the altimeter data the expression of the mean global ocean circulation in the sea surface at the largest scales through a simultaneous solution for gravity, orbital, and oceanographic parameters. (3) Examine the sea surface measurements for changes in global ocean mass or volume, interannual variations in the basin-scale ocean circulation, and annual changes in the heating and cooling of the upper ocean.

  11. The oceanic cycle and global atmospheric budget of carbonyl sulfide

    SciTech Connect

    Weiss, P.S.

    1994-12-31

    A significant portion of stratospheric air chemistry is influenced by the existence of carbonyl sulfide (COS). This ubiquitous sulfur gas represents a major source of sulfur to the stratosphere where it is converted to sulfuric acid aerosol particles. Stratospheric aerosols are climatically important because they scatter incoming solar radiation back to space and are able to increase the catalytic destruction of ozone through gas phase reactions on particle surfaces. COS is primarily formed at the surface of the earth, in both marine and terrestrial environments, and is strongly linked to natural biological processes. However, many gaps in the understanding of the global COS cycle still exist, which has led to a global atmospheric budget that is out of balance by a factor of two or more, and a lack of understanding of how human activity has affected the cycling of this gas. The goal of this study was to focus on COS in the marine environment by investigating production/destruction mechanisms and recalculating the ocean-atmosphere flux.

  12. Comparison of retrospective analyses of the global ocean heat content

    NASA Astrophysics Data System (ADS)

    Chepurin, Gennady A.; Carton, James A.

    1999-07-01

    In this study, we compare seven retrospective analyses of basin- to global-scale upper ocean temperature. The analyses span a minimum of 10 years during the 50-year period since World War II. Three of the analyses (WOA-94, WHITE, BMRC) are based on objective analysis and thus, do not rely on a numerical forecast model. The remaining four (NCEP, WAJSOWICZ, ROSATI, SODA) are based on data assimilation in which the numerical forecast is provided by some form of the Geophysical Fluid Dynamics Laboratory Modular Ocean Model driven by historical winds. The comparison presented here is limited to heat content in the upper 250 m, information that is available for all analyses. The results are presented in three frequency bands: seasonal, interannual (periods of 1-5 years), and decadal (periods of 5-25 years). At seasonal frequencies, all of the analyses are quite similar. Otherwise, the differences among analyses are limited to the regions of the western boundary currents, and some regions in the Southern Hemisphere. At interannual frequencies, significant differences appear between the objective analyses and the data assimilation analyses. Along the equator in the Pacific, where variability is dominated by El Niño, the objective analyses have somewhat noisier fields, as well as reduced variance prior to 1980 due to lack of observations. Still, the correlation among analyses generally exceeds 80% in this region. Along the equator in the Atlantic, the correlation is lower (30-60%) although inspection of the time series shows that the same biennial progression of warm and cool events appears in all analyses since 1980. In the midlatitude Pacific agreement among objective analyses and data assimilation analyses is good. The analysis of Rosati et al. [Rosati, A., Gudgel, R., Miyakoda, K., 1995. Decadal analysis produced from an ocean assimilation system. Mon. Weather Rev., 123, 2, 206.] differs somewhat from the others apparently because in this analysis, the forecast model

  13. Millennial-scale projection of oceanic oxygen change due to global warming

    NASA Astrophysics Data System (ADS)

    Yamamoto, Akitomo; Abe-Ouchi, Ayako; Shigemitsu, Masahito; Oka, Akira; Takahashi, Kunio; Ohgaito, Rumi; Yamanaka, Yasuhiro

    2016-04-01

    Global warming is expected to globally decrease ocean oxygen concentrations by sea surface warming and ocean circulation change. Oxygen reduction is expected to persist for a thousand years or more, even after atmospheric carbon dioxide stops rising. However, long-term changes in ocean oxygen and circulation are still unclear. Here we simulate multimillennium changes in ocean circulation and oxygen under doubling and quadrupling of atmospheric carbon dioxide, using GCM (MIROC) and an offline biogeochemical model. In the first 500 years, global oxygen concentration decreases, consistent with previous studies. Thereafter, however, the oxygen concentration in the deep ocean globally recovers and overshoots at the end of the simulations, despite surface oxygen decrease and weaker AMOC. This is because, after the initial cessation, the recovery and overshooting of deep ocean convection in the Weddell Sea enhance ventilation and supply oxygen-rich surface waters to deep ocean. Another contributor to deep ocean oxygenation is seawater warming, which reduces the export production and shifts the organic matter remineralization to the upper water column. Our results indicate that the change in ocean circulation in the Southern Ocean potentially drives millennial-scale oxygenation in deep ocean, which is opposite to the centennial-scale global oxygen reduction and general expectation.

  14. Global Oceanic Basalt Geochemistry From EarthChem Databases

    NASA Astrophysics Data System (ADS)

    Hofmann, A. W.; Sarbas, B.; Jochum, K. P.; Stracke, A.

    2004-12-01

    For the past 21 years, global trace element systematics in oceanic basalts have been systematically developed, using mass spectrometry, by the MPI geochemistry department in Mainz, starting with Ba-Rb-Cs, and continuing with K-U-Th, Nb-U-Th, Pb-Ce, Pr-Mo, Nb-Ta, Sn-REE, Sb-REE, and Y-Ho relations. These were complemented by other groups, contributing e.g. Sr-REE relationships and more refined Nb-Ta systematics. Goal of these investigations was to establish relative trace element compatibilities during mantle melting, the corresponding enrichment and depletion patterns in MORB, OIB, subduction-related volcanics and the continental crust, and the relationships to Bulk Silicate Earth abundances through comparisons with element abundances in meteorites and in the continental crust (see e.g. [1]). Most of these studies were initially based on extremely limited data sets, often fewer than 100 analyses, because routine analytical techniques such as XRF and INAA were inadequate, either in sensitivity or accuracy or both, for many of the elements of interest. The advent of ICPMS technology has increased the volume of available, useable data enormously. The most recent development of laser source ICPMS is accelerating the acquisition of comprehensive trace element data even more dramatically. Although the general quality of recent trace element analyses has improved significantly, there remain large differences in reliability between published data because of varying analytical uncertainties and sample alteration. Thus, quality assurance remains an enormous task. In any case, now and in the foreseeable future, it will be impossible to assess global geochemical data without the use of comprehensive databases. Such databases are now available under http://www.earthchem.org/, comprising http://beta.petdb.ciesin.columbia.edu/; http://georoc.mpch-mainz.gwdg.de/, and http://navdat.geo.ku.edu/ . Unfortunately, the use of such databases is not without pitfalls. Often, appropriate

  15. Decadal Ocean Heat Content Westward Shift in the Indian Ocean during the Global Surface Warming and Hiatus

    NASA Astrophysics Data System (ADS)

    Wu, X.; Yan, X. H.; Li, Y.

    2015-12-01

    Understanding the ocean's role in Earth's energy budget is fundamental to evaluate climate variability and change, including the rate of global warming and the recent 18-years' so-called Global Surface Warming Hiatus (GSWH). Previous studies have shown that basin-wide warming in the Atlantic Ocean triggers the intensification of trade wind and wind-driven circulation since late 1990s, resulting in Global Surface Warming Hiatus (GSWH). A recent work revealed that missing heat in the Pacific during the GSWH was transported to the Indian Ocean by the Indonesia throughflow. It brings the Indian Ocean to the platform of the GSWH study and suggests that the global ocean is at play in the GSWH and in the ocean heat content (OHC) westwards shifting. The westwards shifting of the OHC was detected from in-situ data and model/in-situ reanalysis data. The shifting has a period of about 30 years, and takes about 60 years to travel from the eastern Pacific to the western Atlantic. Heat was distributed to deeper layers after the warm OHC passed the southern tip of the Africa continent. This may shed light on the understanding of the physical mechanisms for the multi-decadal climate variability.

  16. Global coupling and decoupling of the APS storage ring

    SciTech Connect

    Chae, Y.C.; Liu, J.; Teng, L.C.

    1993-07-01

    This paper describes a study of controlling the coupling between the horizontal and the vertical betatron oscillations in the 7-GeV Advanced Photon Source (APS) storage ring. First, we investigate the strengthening of coupling using two families of skew quadrupoles. Twenty skew quadrupoles are arranged in the 40 sectors of the storage ring and powered in such a way so as to generate both quadrature components of the required 21st harmonic. The numerical results from tracking a single particle are presented for the various configurations of skew quadrupoles. Second, we describe the global decoupling procedure to minimize the unwanted coupling effects. These are mainly due to the random roll errors of normal quadruples. It is shown that even with the rather large rms roll error of 2 mrad, the coupling effects can be compensated for with 20 skew quadrupoles each having maximum strength one order of magnitude lower than the typical normal quadrupole strength.

  17. Co-location of air capture, sub-ocean CO2 storage and energy production on the Kerguelen plateau

    NASA Astrophysics Data System (ADS)

    Goldberg, D.; Han, P.; Lackner, K.; Wang, T.

    2011-12-01

    How can carbon capture and storage activities be sustained from an energy perspective while keeping the entire activity out of sight and away from material risk and social refrain near populated areas? In light of reducing the atmospheric CO2 level to mitigate its effect on climate change, the combination of new air-capture technologies and large offshore storage reservoirs, supplemented by carbon neutral renewable energy, could address both of these engineering and public policy concerns. Because CO2 mixes rapidly in the atmosphere, air capture scrubbers could be located anywhere in the world. Although the power requirements for this technology may reduce net efficiencies, the local availability of carbon-neutral renewable energy for this purpose would eliminate some net energy loss. Certain locations where wind speeds are high and steady, such as those observed at high latitude and across the open ocean, appeal as carbon-neutral energy sources in close proximity to immense and secure reservoirs for geological sequestration of captured CO2. In particular, sub-ocean basalt flows are vast and carry minimal risks of leakage and damages compared to on-land sites. Such implementation of a localized renewable energy source coupled with carbon capture and storage infrastructure could result in a global impact of lowered CO2 levels. We consider an extreme location on the Kerguelen plateau in the southern Indian Ocean, where high wind speeds and basalt storage reservoirs are both plentiful. Though endowed with these advantages, this mid-ocean location incurs clear material and economic challenges due to its remoteness and technological challenges for CO2 capture due to constant high humidity. We study the wind energy-air capture power balance and consider related factors in the feasibility of this location for carbon capture and storage. Other remote oceanic sites where steady winds blow and near large geological reservoirs may be viable as well, although all would require

  18. Global thermohaline circulation and ocean-atmosphere coupling

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoli

    1997-09-01

    A global ocean general circulation model (GCM) with idealized geometry (two basins of equal size, Marotzke and Willebrand, 1991) is coupled to an energy balance atmospheric model with nonlinear parameterizations of meridional atmospheric transports of heat and moisture. With the coupled model that prescribes the atmospheric heat and moisture transports, the North Atlantic meridional mass overturning rates at equilibrium increases as the global hydrological cycle strength increases. Furthermore, the equilibrium overturning rate is primarily controlled by the hydrological cycle of the Southern Hemisphere, whereas the Northern Hemispheric hydrological cycle has little impact. The transition of the thermohaline circulation from the conveyor belt to the southern sinking state is controlled by two factors, the hydrological cycle in Northern Hemisphere, and the ratio of hydrological cycle strengths between the Northern Hemisphere and the Southern Hemisphere. Increasing either of them destabilizes the thermohaline circulation. The large-scale dynamics of the North Atlantic overturning is mainly interhemispheric, with the bulk of the overturning rising in the Southern Hemisphere. Multiple intermediate states exist that are only quantitatively different, under very small salinity perturbations. The coupled feedbacks between the thermohaline circulation and the atmospheric heat and moisture transports are demonstrated to exist in the coupled model, and all of them are positive. In addition, it is identified that the coupled feedbacks associated with the atmospheric transports in the Southern Hemisphere are also positive. Two different flux adjustments are used in the coupled model, with one adjusting the atmospheric transports efficiencies, the other adjusting the surface fluxes. Different flux adjustments influence the coupled feedback intensities, and hence the stability of the thermohaline circulation. (Copies available exclusively from MIT Libraries, Rm. 14

  19. Volume, heat, and freshwater transports of the global ocean circulation 1993-2000, estimated from a general circulation model constrained by World Ocean Circulation Experiment (WOCE) data

    NASA Astrophysics Data System (ADS)

    Stammer, D.; Wunsch, C.; Giering, R.; Eckert, C.; Heimbach, P.; Marotzke, J.; Adcroft, A.; Hill, C. N.; Marshall, J.

    2003-01-01

    An analysis of ocean volume, heat, and freshwater transports from a fully constrained general circulation model (GCM) is described. Output from a data synthesis, or state estimation, method is used by which the model was forced to large-scale, time-varying global ocean data sets over 1993 through 2000. Time-mean horizontal transports, estimated from this fully time-dependent circulation, have converged with independent time-independent estimates from box inversions over most parts of the world ocean but especially in the southern hemisphere. However, heat transport estimates differ substantially in the North Atlantic where our estimates result in only 1/2 previous results. The models drift over the estimation period is consistent with observations from TOPEX/Poseidon in their spatial pattern, but smaller in their amplitudes by about a factor of 2. Associated temperature and salinity changes are complex, and both point toward air-sea interaction over water mass formation regions as the primary source for changes in the deep ocean. The estimated mean circulation around Australia involves a net volume transport of 11 Sv through the Indonesian Throughflow and the Mozambique Channel. In addition, we show that this flow regime exists on all timescales above 1 month, rendering the variability in the South Pacific strongly coupled to the Indian Ocean. Moreover, the dynamically consistent variations in the model show temporal variability of oceanic heat transports, heat storage, and atmospheric exchanges that are complex and with a strong dependence upon location, depth, and timescale. Our results demonstrate the great potential of an ocean state estimation system to provide a dynamical description of the time-dependent observed heat transport and heat content changes and their relation to air-sea interactions.

  20. The Ocean as a Global Reservoir of Antibiotic Resistance Genes

    PubMed Central

    Hatosy, Stephen M.

    2015-01-01

    Recent studies of natural environments have revealed vast genetic reservoirs of antibiotic resistance (AR) genes. Soil bacteria and human pathogens share AR genes, and AR genes have been discovered in a variety of habitats. However, there is little knowledge about the presence and diversity of AR genes in marine environments and which organisms host AR genes. To address this, we identified the diversity of genes conferring resistance to ampicillin, tetracycline, nitrofurantoin, and sulfadimethoxine in diverse marine environments using functional metagenomics (the cloning and screening of random DNA fragments). Marine environments were host to a diversity of AR-conferring genes. Antibiotic-resistant clones were found at all sites, with 28% of the genes identified as known AR genes (encoding beta-lactamases, bicyclomycin resistance pumps, etc.). However, the majority of AR genes were not previously classified as such but had products similar to proteins such as transport pumps, oxidoreductases, and hydrolases. Furthermore, 44% of the genes conferring antibiotic resistance were found in abundant marine taxa (e.g., Pelagibacter, Prochlorococcus, and Vibrio). Therefore, we uncovered a previously unknown diversity of genes that conferred an AR phenotype among marine environments, which makes the ocean a global reservoir of both clinically relevant and potentially novel AR genes. PMID:26296734

  1. A Multiyear Dataset of SSM/I-Derived Global Ocean Surface Turbulent Fluxes

    NASA Technical Reports Server (NTRS)

    Chou, Shu-Hsien; Shie, Chung-Lin; Atlas, Robert M.; Ardizzone, Joe; Nelkin, Eric; Einaudi, Franco (Technical Monitor)

    2001-01-01

    The surface turbulent fluxes of momentum, latent heat, and sensible heat over global oceans are essential to weather, climate and ocean problems. Evaporation is a key component of the hydrological cycle and the surface heat budget, while the wind stress is the major forcing for driving the oceanic circulation. The global air-sea fluxes of momentum, latent and sensible heat, radiation, and freshwater (precipitation-evaporation) are the forcing for driving oceanic circulation and, hence, are essential for understanding the general circulation of global oceans. The global air-sea fluxes are required for driving ocean models and validating coupled ocean-atmosphere global models. We have produced a 7.5-year (July 1987-December 1994) dataset of daily surface turbulent fluxes over the global oceans from the Special Sensor microwave/Imager (SSM/I) data. Daily turbulent fluxes were derived from daily data of SSM/I surface winds and specific humidity, National Centers for Environmental Prediction (NCEP) sea surface temperatures, and European Centre for Medium-Range Weather Forecasts (ECMWF) air-sea temperature differences, using a stability-dependent bulk scheme. The retrieved instantaneous surface air humidity (with a 25-km resolution) validated well with that of the collocated radiosonde observations over the global oceans. Furthermore, the retrieved daily wind stresses and latent heat fluxes were found to agree well with that of the in situ measurements (IMET buoy, RV Moana Wave, and RV Wecoma) in the western Pacific warm pool during the TOGA COARE intensive observing period (November 1992-February 1993). The global distributions of 1988-94 seasonal-mean turbulent fluxes will be presented. In addition, the global distributions of 1990-93 annual-means turbulent fluxes and input variables will be compared with those of UWM/COADS covering the same period. The latter is based on the COADS (comprehensive ocean-atmosphere data set) and is recognized to be one of the best

  2. XBT effects on the global ocean observation system in the early 21st century

    NASA Astrophysics Data System (ADS)

    Chang, You-Soon; Zhang, Shaoqing

    2016-04-01

    During the early 21st century, we have experienced a transition period of global ocean observing system from expendable bathythermograph (XBT) to Argo. There has been decreasing of XBT observations, but significant increasing of Argo profiles in the global ocean. However, evaluation of the XBT observation system during this period has little been presented. Here, this study investigates the XBT effects on the global ocean observing system by using GFDL data assimilation model. After Argo period, the amount of heat content correction by XBT assimilation is significantly weaken especially in the upper ocean, but it remains in the deeper oceans below 700 m depth within a dynamic model system. This study also confirms that although XBT only provides temperature observations mostly in the upper 700 m of the northern hemisphere, it can affects both temperature and salinity fields of data assimilation system especially in the deep and southern oceans.

  3. On Verifying Currents and Other Features in the Hawaiian Islands Region Using Fully Coupled Ocean/Atmosphere Mesoscale Prediction System Compared to Global Ocean Model and Ocean Observations

    NASA Astrophysics Data System (ADS)

    Jessen, P. G.; Chen, S.

    2014-12-01

    This poster introduces and evaluates features concerning the Hawaii, USA region using the U.S. Navy's fully Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS-OS™) coupled to the Navy Coastal Ocean Model (NCOM). It also outlines some challenges in verifying ocean currents in the open ocean. The system is evaluated using in situ ocean data and initial forcing fields from the operational global Hybrid Coordinate Ocean Model (HYCOM). Verification shows difficulties in modelling downstream currents off the Hawaiian islands (Hawaii's wake). Comparing HYCOM to NCOM current fields show some displacement of small features such as eddies. Generally, there is fair agreement from HYCOM to NCOM in salinity and temperature fields. There is good agreement in SSH fields.

  4. Global oceanic emission of ammonia: Constraints from seawater and atmospheric observations

    NASA Astrophysics Data System (ADS)

    Paulot, F.; Jacob, D. J.; Johnson, M. T.; Bell, T. G.; Baker, A. R.; Keene, W. C.; Lima, I. D.; Doney, S. C.; Stock, C. A.

    2015-08-01

    Current global inventories of ammonia emissions identify the ocean as the largest natural source. This source depends on seawater pH, temperature, and the concentration of total seawater ammonia (NHx(sw)), which reflects a balance between remineralization of organic matter, uptake by plankton, and nitrification. Here we compare [NHx(sw)] from two global ocean biogeochemical models (BEC and COBALT) against extensive ocean observations. Simulated [NHx(sw)] are generally biased high. Improved simulation can be achieved in COBALT by increasing the plankton affinity for NHx within observed ranges. The resulting global ocean emissions is 2.5 TgN a-1, much lower than current literature values (7-23 TgN a-1), including the widely used Global Emissions InitiAtive (GEIA) inventory (8 TgN a-1). Such a weak ocean source implies that continental sources contribute more than half of atmospheric NHx over most of the ocean in the Northern Hemisphere. Ammonia emitted from oceanic sources is insufficient to neutralize sulfate aerosol acidity, consistent with observations. There is evidence over the Equatorial Pacific for a missing source of atmospheric ammonia that could be due to photolysis of marine organic nitrogen at the ocean surface or in the atmosphere. Accommodating this possible missing source yields a global ocean emission of ammonia in the range 2-5 TgN a-1, comparable in magnitude to other natural sources from open fires and soils.

  5. Assimilation of TOPEX/POSEIDON Altimeter Data into a Global Ocean Circulation Model: Are the Results Any Good?

    NASA Technical Reports Server (NTRS)

    Fukumori, I.; Fu, L. L.; Chao, Y.

    1998-01-01

    The feasibility of assimilating satellite altimetry data into a global ocean general ocean general circulation model is studied. Three years of TOPEX/POSEIDON data is analyzed using a global, three-dimensional, nonlinear primitive equation model.

  6. Climatic and anthropogenic factors affecting river discharge to the global ocean, 1951-2000

    USGS Publications Warehouse

    Milliman, John D.; Farnsworth, K.L.; Jones, P.D.; Xu, K.H.; Smith, L.C.

    2008-01-01

    During the last half of the 20th century, cumulative annual discharge from 137 representative rivers (watershed areas ranging from 0.3 to 6300 ?? 103??km2) to the global ocean remained constant, although annual discharge from about one-third of these rivers changed by more than 30%. Discharge trends for many rivers reflected mostly changes in precipitation, primarily in response to short- and longer-term atmospheric-oceanic signals; with the notable exception of the Parana, Mississippi, Niger and Cunene rivers, few of these "normal" rivers experienced significant changes in either discharge or precipitation. Cumulative discharge from many mid-latitude rivers, in contrast, decreased by 60%, reflecting in large part impacts due to damming, irrigation and interbasin water transfers. A number of high-latitude and high-altitude rivers experienced increased discharge despite generally declining precipitation. Poorly constrained meteorological and hydrological data do not seem to explain fully these "excess" rivers; changed seasonality in discharge, decreased storage and/or decreased evapotranspiration also may play important roles. ?? 2008 Elsevier B.V. All rights reserved.

  7. Are Global In-Situ Ocean Observations Fit-for-purpose? Applying the Framework for Ocean Observing in the Atlantic.

    NASA Astrophysics Data System (ADS)

    Visbeck, M.; Fischer, A. S.; Le Traon, P. Y.; Mowlem, M. C.; Speich, S.; Larkin, K.

    2015-12-01

    There are an increasing number of global, regional and local processes that are in need of integrated ocean information. In the sciences ocean information is needed to support physical ocean and climate studies for example within the World Climate Research Programme and its CLIVAR project, biogeochemical issues as articulated by the GCP, IMBER and SOLAS projects of ICSU-SCOR and Future Earth. This knowledge gets assessed in the area of climate by the IPCC and biodiversity by the IPBES processes. The recently released first World Ocean Assessment focuses more on ecosystem services and there is an expectation that the Sustainable Development Goals and in particular Goal 14 on the Ocean and Seas will generate new demands for integrated ocean observing from Climate to Fish and from Ocean Resources to Safe Navigation and on a healthy, productive and enjoyable ocean in more general terms. In recognition of those increasing needs for integrated ocean information we have recently launched the Horizon 2020 AtlantOS project to promote the transition from a loosely-coordinated set of existing ocean observing activities to a more integrated, more efficient, more sustainable and fit-for-purpose Atlantic Ocean Observing System. AtlantOS takes advantage of the Framework for Ocean observing that provided strategic guidance for the design of the project and its outcome. AtlantOS will advance the requirements and systems design, improving the readiness of observing networks and data systems, and engaging stakeholders around the Atlantic. AtlantOS will bring Atlantic nations together to strengthen their complementary contributions to and benefits from the internationally coordinated Global Ocean Observing System (GOOS) and the Blue Planet Initiative of the Global Earth Observation System of Systems (GEOSS). AtlantOS will fill gaps of the in-situ observing system networks and will ensure that their data are readily accessible and useable. AtlantOS will demonstrate the utility of

  8. MERCATOR-Ocean monitoring and forecasting : a 4D vision of the global ocean. Data policy and applications.

    NASA Astrophysics Data System (ADS)

    Toumazou, V.; Nouel, L.; Sureau, J.; Greiner, E.; Landes, V.; Dombrowsky, E.; Charon, I.

    2003-12-01

    Mercator Ocean is a public interest grouping formed in Toulouse in early 2002 by six major players in the French oceanography community: the space agency CNES, the scientific research centre CNRS, IFREMER (the institute of marine research and exploration), the development research institute IRD, the Météo France weather service, and SHOM (the French Navy's hydrography & oceanography department). In 1995, these same organizations gave themselves seven years to achieve a challenging objective: to conceive, develop and implement France's first operational oceanography system. The unique system would be capable of describing, analysing and predicting conditions at the ocean surface and subsurface in real time, anytime, anywhere in the world, even in the most inhospitable seas. That objective was met on 17 January 2001 with the release of the first Mercator ocean bulletin, providing a two-week forecast for the entire North Atlantic. Two thousands new forecast charts are now added to the MERCATOR bulletin every week. Building on these successes, a dedicated operational oceanography team, Mercator Ocean, was set up in 2002. Mercator Ocean's mission is to deliver incremental improvements in the service provided by this new operational oceanography capability by increasing the resolution and the geographic coverage of the models used. The new high-resolution model that is now on line offers 6 km grid resolution, and the first models offering global ocean coverage will be implemented late 2003. Over the next four years, Mercator Ocean also plans to establish a European Operational Oceanography Centre in Toulouse. Objective 1. Develop an operational oceanography system using three-dimensional simulation and a high-resolution primitive-equation model capable of assimilating satellite data (from the Jason altimetry satellite in particular) and in-situ ocean observation data (particularly those gathered by the CORIOLIS centre). 2. Support applications for commercial shipping

  9. TARA OCEANS: A Global Analysis of Oceanic Plankton Ecosystems (2013 DOE JGI Genomics of Energy and Environment 8th Annual User Meeting)

    SciTech Connect

    Karsenti, Eric

    2013-03-01

    Eric Karsenti of EMBL delivers the closing keynote on "TARA OCEANS: A Global Analysis of Oceanic Plankton Ecosystems" at the 8th Annual Genomics of Energy & Environment Meeting on March 28, 2013 in Walnut Creek, Calif.

  10. Keeping the lights on for global ocean salinity observation

    NASA Astrophysics Data System (ADS)

    Durack, Paul J.; Lee, Tong; Vinogradova, Nadya T.; Stammer, Detlef

    2016-03-01

    Insights about climate are being uncovered thanks to improved capacities to observe ocean salinity, an essential climate variable. However, cracks are beginning to appear in the ocean observing system that require prompt attention if we are to maintain the existing, hard-won capacity into the near future.

  11. Keeping the lights on for global ocean salinity observation

    DOE PAGESBeta

    Durack, Paul J.; Lee, Tong; Vinogradova, Nadya T.; Stammer, Detlef

    2016-02-24

    Here, insights about climate are being uncovered thanks to improved capacities to observe ocean salinity, an essential climate variable. However, cracks are beginning to appear in the ocean observing system that require prompt attention if we are to maintain the existing, hard-won capacity into the near future.

  12. Validation of GLORYS ocean bottom pressure using global high resolution GRACE mascon solutions

    NASA Astrophysics Data System (ADS)

    Boy, Jean-Paul; Rowlands, David; Luthcke, Scott; Sabaka, Terence; Lemoine, Frank; Ferry, Nicolas; Parent, Laurent

    2010-05-01

    We present the comparison of oceanic mass variations deduced from GLORYS1V1 (GLobal Ocean ReanalYses and Simulations) eddy-resolving ocean model and derived from a global high resolution GRACE (Gravity Recovery And Climate Experiment) mascon solution (Rowlands et al., 2010), for the period 2003-2008. Compared to the classical spherical harmonic solutions, the mascon (mass concentration) technique allows the retrieval of mass variations at the Earth's surface with higher temporal and spatial sampling (2 degrees and 10 days). The forward modeling of hydrology using GLDAS (Global Land Data Assimilation System) also reduces the leakage of continental hydrology into the oceans, demonstrating that the global mascon solution developed at NASA Goddard Space Flight Center (Rowlands et al., 2010) is optimal for studying global oceanic circulation. GLORYS1V1 is the first implementation of the global eddy-resolving (1/4 degree) ocean reanalysis performed by Mecator-Océan, covering the ARGO period (2002-2008). The model assimilate sea-surface height variations from radar altimetry (AVISO), sea-surface temperature (Reynolds) and in-situ temperature and salinity measurements (CORIOLIS).We also show the comparison, in terms of ocean bottom pressure variations, with the 1/4 degree operational (PSY3) models. In addition, we compare and validate both GLORYS and GRACE estimated bottom pressure variations to an independent datasets of bottom pressure records.

  13. Strong coupling among Antarctic ice shelves, ocean circulation and sea ice in a global sea-ice - ocean circulation model

    NASA Astrophysics Data System (ADS)

    Sergienko, Olga

    2016-04-01

    The thermodynamic effects of Antarctic ice shelf interaction with ocean circulation are investigated using a global, high-resolution, isopycnal ocean-circulation model coupled to a sea-ice model. The model uses NASA MERRA Reanalysis from 1992 to 2011 as atmospheric forcing. The simulated long-period variability of ice-shelf melting/freezing rates differ across geographic locations. The ice shelves in Antarctic Peninsula, Amundsen and Bellingshausen sea embayments and the Amery Ice Shelf experience an increase in melting starting from 2005. This increase in melting is due to an increase in the subsurface (100-500 m) ocean heat content in the embayments of these ice shelves, which is caused by an increase in sea-ice concentration after 2005, and consequent reduction of the heat loss to the atmosphere. Our simulations provide a strong evidence for a coupling between ocean circulation, sea ice and ice shelves.

  14. Role of Indian Ocean SST variability on the recent global warming hiatus

    NASA Astrophysics Data System (ADS)

    Arora, Anika; Rao, Suryachandra A.; Chattopadhyay, R.; Goswami, Tanmoy; George, Gibies; Sabeerali, C. T.

    2016-08-01

    Previous studies have shown a slowdown in the warming rate of the annual mean global surface temperature in the recent decade and it is referred to as the hiatus in global warming. Some recent studies have suggested that the hiatus in global warming is possibly due to strong cooling in the tropical Pacific. This study investigates the possible role of the Indian Ocean warming on the tropical Pacific cooling. Despite the continued rise in sea surface temperature (SST) over the tropical Indian Ocean, SST over the tropical Pacific has shown a cooling trend in the recent decade (2002 - 2012). It is well known fact that the Indian Ocean and the Pacific Ocean are strongly coupled to each other and the Indian Ocean basin wide warming is triggered by El Niño on interannual time scale. However, in the recent decade, this relationship is weakening. The recent Indian Ocean warming is triggering a Matsuno-Gill type response in the atmosphere by generating anomalous cyclonic circulations on either side of equator over the tropical Indian Ocean and anomalous easterlies along the tropical Pacific Ocean. These anomalous easterlies result in Ekman divergence in the equatorial Pacific and produce upwelling Kelvin waves, cools the tropical Pacific and therefore indirectly contributes to the hiatus in global warming.

  15. Trends and drivers in global surface ocean pH over the past three decades

    NASA Astrophysics Data System (ADS)

    Lauvset, S. K.; Gruber, N.; Landschützer, P.; Olsen, A.; Tjiputra, J.

    2014-11-01

    We report global long-term trends in surface ocean pH using a new pH data set computed by combining fCO2 observations from the Surface Ocean CO2 Atlas (SOCAT) version 2 with surface alkalinity estimates based on temperature and salinity. Trends were determined over the periods 1981-2011 and 1991-2011 for a set of 17 biomes using a weighted linear least squares method. We observe significant decreases in surface ocean pH in ~70% of all biomes and a global mean rate of decrease of -0.0018 ± 0.0004 yr-1 for 1991-2011. We are not able to calculate a global trend for 1981-2011 because too few biomes have enough data for this. In two-thirds of the biomes, the rate of change is commensurate with the trends expected based on the assumption that the surface ocean pH change is only driven by the surface ocean carbon chemistry remaining in a transient equilibrium with the increase in atmospheric CO2. In the remaining biomes deviations from such equilibrium may reflect changes in the trend of surface ocean fCO2, most notably in the equatorial Pacific Ocean, or changes in the oceanic buffer (Revelle) factor. We conclude that well-planned and long-term sustained observational networks are key to reliably document the ongoing and future changes in ocean carbon chemistry due to anthropogenic forcing.

  16. Visualization and analysis of eddies in a global ocean simulation

    SciTech Connect

    Williams, Sean J; Hecht, Matthew W; Petersen, Mark; Strelitz, Richard; Maltrud, Mathew E; Ahrens, James P; Hlawitschka, Mario; Hamann, Bernd

    2010-10-15

    Eddies at a scale of approximately one hundred kilometers have been shown to be surprisingly important to understanding large-scale transport of heat and nutrients in the ocean. Due to difficulties in observing the ocean directly, the behavior of eddies below the surface is not very well understood. To fill this gap, we employ a high-resolution simulation of the ocean developed at Los Alamos National Laboratory. Using large-scale parallel visualization and analysis tools, we produce three-dimensional images of ocean eddies, and also generate a census of eddy distribution and shape averaged over multiple simulation time steps, resulting in a world map of eddy characteristics. As expected from observational studies, our census reveals a higher concentration of eddies at the mid-latitudes than the equator. Our analysis further shows that mid-latitude eddies are thicker, within a range of 1000-2000m, while equatorial eddies are less than 100m thick.

  17. Global warming: Growing feedback from ocean carbon to climate

    NASA Astrophysics Data System (ADS)

    Joos, Fortunat

    2015-06-01

    The finding that feedbacks between the ocean's carbon cycle and climate may become larger than terrestrial carbon-climate feedbacks has implications for the socio-economic effects of today's fossil-fuel emissions.

  18. Global Bathymetric Prediction For Ocean Modeling and Marine Geophysics

    NASA Technical Reports Server (NTRS)

    Sandwell, David T.; Smith, Walter H. F.; Sichoix, Lydie; Frey, Herbert V. (Technical Monitor)

    2001-01-01

    We proposed to construct a complete bathymetric map of the oceans at a 3-10 km resolution by combining all of the available depth soundings collected over the past 30 years with high resolution marine gravity information provided by the Geosat, ERS-1/2, and Topex/Poseidon altimeters. Detailed bathymetry is essential for understanding physical oceanography and marine geophysics. Currents and tides are controlled by the overall shapes of the ocean basins as well as the smaller sharp ocean ridges and seamounts. Because erosion rates are low in the deep oceans, detailed bathymetry reveals the mantle convection patterns, the plate boundaries, the cooling/subsidence of the oceanic lithosphere, the oceanic plateaus, and the distribution of off-ridge volcanoes. We proposed to: (1) Accumulate all available depth soundings collected over the past 30 years; (2) Use the short wavelength (< 160 km) satellite gravity information to interpolate between sparse ship soundings; (3) Improve the resolution of the marine gravity field using enhanced estimates along repeat altimeter profiles together with the dense altimeter measurements; (4) Refine/improve bathymetric predictions using the improved resolution gravity field and also by investigating computer-intensive methods for bathymetric prediction such as inverse theory; and (5) Produce a 'Globe of the Earth' similar to the globe of Venus prepared by the NASA Magellan investigation. This will also include the best available digital land data.

  19. Sensitivity of global ocean heat content from reanalyses to the atmospheric reanalysis forcing: A comparative study

    NASA Astrophysics Data System (ADS)

    Storto, Andrea; Yang, Chunxue; Masina, Simona

    2016-05-01

    The global ocean heat content evolution is a key component of the Earth's energy budget and can be consistently determined by ocean reanalyses that assimilate hydrographic profiles. This work investigates the impact of the atmospheric reanalysis forcing through a multiforcing ensemble ocean reanalysis, where the ensemble members are forced by five state-of-the-art atmospheric reanalyses during the meteorological satellite era (1979-2013). Data assimilation leads the ensemble to converge toward robust estimates of ocean warming rates and significantly reduces the spread (1.48 ± 0.18 W/m2, per unit area of the World Ocean); hence, the impact of the atmospheric forcing appears only marginal for the global heat content estimates in both upper and deeper oceans. A sensitivity assessment performed through realistic perturbation of the main sources of uncertainty in ocean reanalyses highlights that bias correction and preprocessing of in situ observations represent the most crucial component of the reanalysis, whose perturbation accounts for up to 60% of the ocean heat content anomaly variability in the pre-Argo period. Although these results may depend on the single reanalysis system used, they reveal useful information for the ocean observation community and for the optimal generation of perturbations in ocean ensemble systems.

  20. CLIVAR-GSOP/GODAE Ocean Synthesis Inter-Comparison of Global Air-Sea Fluxes From Ocean and Coupled Reanalyses

    NASA Astrophysics Data System (ADS)

    Valdivieso, Maria

    2014-05-01

    The GODAE OceanView and CLIVAR-GSOP ocean synthesis program has been assessing the degree of consistency between global air-sea flux data sets obtained from ocean or coupled reanalyses (Valdivieso et al., 2014). So far, fifteen global air-sea heat flux products obtained from ocean or coupled reanalyses have been examined: seven are from low-resolution ocean reanalyses (BOM PEODAS, ECMWF ORAS4, JMA/MRI MOVEG2, JMA/MRI MOVECORE, Hamburg Univ. GECCO2, JPL ECCOv4, and NCEP GODAS), five are from eddy-permitting ocean reanalyses developed as part of the EU GMES MyOcean program (Mercator GLORYS2v1, Reading Univ. UR025.3, UR025.4, UKMO GloSea5, and CMCC C-GLORS), and the remaining three are couple reanalyses based on coupled climate models (JMA/MRI MOVE-C, GFDL ECDA and NCEP CFSR). The global heat closure in the products over the period 1993-2009 spanned by all data sets is presented in comparison with observational and atmospheric reanalysis estimates. Then, global maps of ensemble spread in the seasonal cycle, and of the Signal to Noise Ratio of interannual flux variability over the 17-yr common period are shown to illustrate the consistency between the products. We have also studied regional variability in the products, particularly at the OceanSITES project locations (such as, for instance, the TAO/TRITON and PIRATA arrays in the Tropical Pacific and Atlantic, respectively). Comparisons are being made with other products such as OAFlux latent and sensible heat fluxes (Yu et al., 2008) combined with ISCCP satellite-based radiation (Zhang et al., 2004), the ship-based NOC2.0 product (Berry and Kent, 2009), the Large and Yeager (2009) hybrid flux dataset CORE.2, and two atmospheric reanalysis products, the ECMWF ERA-Interim reanalysis (referred to as ERAi, Dee et al., 2011) and the NCEP/DOE reanalysis R2 (referred to as NCEP-R2, Kanamitsu et al., 2002). Preliminary comparisons with the observational flux products from OceanSITES are also underway. References Berry, D

  1. Ocean Front Detection from MERIS and OLCI Ocean Colour Data Applied to Marine Conservation and Global Oceanography

    NASA Astrophysics Data System (ADS)

    Miller, Peter I.

    2015-12-01

    Ocean front detection and aggregation techniques were recently applied to 300m resolution Medium Resolution Imaging Spectrometer (MERIS) satellite ocean colour data for the first time, to describe frequently occurring shelf-sea fronts near to the Scottish coast (Miller et al., in press). This resolution enabled the location of smaller frontal zones and those in close proximity to a convoluted coastline, and was used to identify zones of ecological importance that could assist the process of defining marine protected areas. Frequent front zones are associated with higher abundance of plankton, certain pelagic fish and megafauna. This paper anticipates the improved insights into submesoscale sediment and plankton dynamics that will result from application of these techniques to the Ocean and Land Colour Instrument (OLCI) on Sentinel-3a and 3b. Looking to the global scale, we show global chlorophyll-a fronts, eddies and other structures detected from the ESA Ocean Colour Climate Change Initiative daily 4 km resolution merged dataset derived from MERIS, SeaWiFS and MODIS data. This emphasises the importance of the Sentinel missions to improving study of both physical and biological ocean processes.

  2. Penetration of UV-visible solar radiation in the global oceans: Insights from ocean color remote sensing

    NASA Astrophysics Data System (ADS)

    Lee, Zhongping; Hu, Chuanmin; Shang, Shaoling; Du, Keping; Lewis, Marlon; Arnone, Robert; Brewin, Robert

    2013-09-01

    Penetration of solar radiation in the ocean is determined by the attenuation coefficient (Kd(λ)). Following radiative transfer theory, Kd is a function of angular distribution of incident light and water's absorption and backscattering coefficients. Because these optical products are now generated routinely from satellite measurements, it is logical to evolve the empirical Kd to a semianalytical Kd that is not only spectrally flexible, but also the sun-angle effect is accounted for explicitly. Here, the semianalytical model developed in Lee et al. (2005b) is revised to account for the shift of phase function between molecular and particulate scattering from the short to long wavelengths. Further, using field data collected independently from oligotrophic ocean to coastal waters covering >99% of the Kd range for the global oceans, the semianalytically derived Kd was evaluated and found to agree with measured data within ˜7-26%. The updated processing system was applied to MODIS measurements to reveal the penetration of UVA-visible radiation in the global oceans, where an empirical procedure to correct Raman effect was also included. The results indicated that the penetration of the blue-green radiation for most oceanic waters is ˜30-40% deeper than the commonly used euphotic zone depth; and confirmed that at a depth of 50-70 m there is still ˜10% of the surface UVA radiation (at 360 nm) in most oligotrophic waters. The results suggest a necessity to modify or expand the light attenuation product from satellite ocean-color measurements in order to be more applicable for studies of ocean physics and biogeochemistry.

  3. Pliocene three-dimensional global ocean temperature reconstruction

    USGS Publications Warehouse

    Dowsett, H.J.; Robinson, M.M.; Foley, K.M.

    2009-01-01

    The thermal structure of the mid-Piacenzian ocean 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 Ocean 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 Ocean. In the Southern Ocean, the Polar Front Zone was expanded relative to present day, but shifted closer to the Antarctic continent. This, combined with at least seasonal reduction in sea ice extent, resulted in decreased Antarctic 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 ocean 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.

  4. Pliocene three-dimensional global ocean temperature reconstruction

    USGS Publications Warehouse

    Dowsett, H.J.; Robinson, M.M.; Foley, K.M.

    2009-01-01

    A snapshot of the thermal structure of the mid-Piacenzian ocean 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 Ocean 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 Ocean. In the Southern Ocean, the Polar Front Zone was expanded relative to present day, but shifted closer to the Antarctic continent. This, combined with at least seasonal reduction in sea ice extent, resulted in decreased Antarctic 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 ocean 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.

  5. New features of global climatology revealed by satellite-derived oceanic rainfall maps

    NASA Technical Reports Server (NTRS)

    Rao, M. S. V.; Theon, J. S.

    1977-01-01

    Quantitative rainfall maps over the oceanic areas of the globe were derived from the Nimbus 5 Electrically Scanning Microwave Radiometer (ESMR) data. Analysis of satellite derived oceanic rainfall maps reveal certain distinctive characteristics of global patterns for the years 1973-74. The main ones are (1) the forking of the Intertropical Convergence Zone in the Pacific, (2) a previously unrecognized rain area in the South Atlantic, (3) the bimodal behavior of rainbelts in the Indian Ocean and (4) the large interannual variability in oceanic rainfall. These features are discussed.

  6. The polar oceans and their role in shaping the global environment

    SciTech Connect

    Johannessen, O.M.; Muench, R.D.; Overland, J.E.

    1994-12-31

    This book is a comprehensive treatment of major advances made in the past decade in understanding of the interactions between polar oceans and the local atmosphere and ocean system. Included are 38 papers discussing the circulation, dynamics and convective processes occurring in the polar oceans; its carbon cycle chemistry and biology; the paleooceanography and paleoclimate of the polar regions; the interaction between the polar ocean and the global climate, and a variety of strategies for detection of climate change in polar regions, predominantly Arctic.

  7. Oceanic Carbon Dioxide Uptake in a Model of Century-Scale Global Warming

    PubMed

    Sarmiento; Le Quéré C

    1996-11-22

    In a model of ocean-atmosphere interaction that excluded biological processes, the oceanic uptake of atmospheric carbon dioxide (CO2) was substantially reduced in scenarios involving global warming relative to control scenarios. The primary reason for the reduced uptake was the weakening or collapse of the ocean thermohaline circulation. Such a large reduction in this ocean uptake would have a major impact on the future growth rate of atmospheric CO2. Model simulations that include a simple representation of biological processes show a potentially large offsetting effect resulting from the downward flux of biogenic carbon. However, the magnitude of the offset is difficult to quantify with present knowledge. PMID:8910268

  8. Global Upper Ocean Salinity Change in the Recent Years 2006 to 2010

    NASA Astrophysics Data System (ADS)

    Ren, L.; Hackert, E. C.; Arkin, P. A.; Busalacchi, A. J.

    2011-12-01

    Recent satellite missions, such as Aquarius and the European Soil Moisture/Ocean Salinity (SMOS) are designed to observe sea surface salinity on a global scale with an accuracy of 0.2 PSU on a monthly basis . It is envisioned that these satellites will provide an unprecedented view of SSS leading to a better estimate of the global salinity budget. However, until enough data become available from these satellites, in situ observations are utilized to make large scale estimates of the salinity trend. Data from Argo floats indicate that mean salinity in the upper 700 m of the global ocean has increased from 2006 to 2010. Such a salinity change implies a net freshwater loss from the ocean to the atmosphere. Oceanic precipitation observations are extremely limited, but large scale data sets have been developed using estimates derived from both satellite observations and atmospheric data assimilation systems. In this presentation, precipitation products including GPCP, CMAP, MERRA and NCEP-CFSR are used to investigate the freshwater changes. The global ocean average of the precipitation shows a decrease during the time period of 2006 to 2010, consistent with the salinity change. We will describe the spatial patterns of these changes in both salinity and precipitation during this time period, and compare the areal integrals with the other components of the spatially averaged oceanic freshwater budget. In addition, we will put the upper layer salinity and precipitation trends into context by comparing these observations with longer time series of oceanic/atmospheric reanalysis data.

  9. How well do global ocean biogeochemistry models simulate dissolved iron distributions?

    NASA Astrophysics Data System (ADS)

    Tagliabue, Alessandro; Aumont, Olivier; DeAth, Ros; Dunne, John P.; Dutkiewicz, Stephanie; Galbraith, Eric; Misumi, Kazuhiro; Moore, J. Keith; Ridgwell, Andy; Sherman, Elliot; Stock, Charles; Vichi, Marcello; Völker, Christoph; Yool, Andrew

    2016-02-01

    Numerical models of ocean biogeochemistry are relied upon to make projections about the impact of climate change on marine resources and test hypotheses regarding the drivers of past changes in climate and ecosystems. In large areas of the ocean, iron availability regulates the functioning of marine ecosystems and hence the ocean carbon cycle. Accordingly, our ability to quantify the drivers and impacts of fluctuations in ocean ecosystems and carbon cycling in space and time relies on first achieving an appropriate representation of the modern marine iron cycle in models. When the iron distributions from 13 global ocean biogeochemistry models are compared against the latest oceanic sections from the GEOTRACES program, we find that all models struggle to reproduce many aspects of the observed spatial patterns. Models that reflect the emerging evidence for multiple iron sources or subtleties of its internal cycling perform much better in capturing observed features than their simpler contemporaries, particularly in the ocean interior. We show that the substantial uncertainty in the input fluxes of iron results in a very wide range of residence times across models, which has implications for the response of ecosystems and global carbon cycling to perturbations. Given this large uncertainty, iron fertilization experiments based on any single current generation model should be interpreted with caution. Improvements to how such models represent iron scavenging and also biological cycling are needed to raise confidence in their projections of global biogeochemical change in the ocean.

  10. Role of zooplankton dynamics for Southern Ocean phytoplankton biomass and global biogeochemical cycles

    NASA Astrophysics Data System (ADS)

    Le Quéré, C.; Buitenhuis, E. T.; Moriarty, R.; Alvain, S.; Aumont, O.; Bopp, L.; Chollet, S.; Enright, C.; Franklin, D. J.; Geider, R. J.; Harrison, S. P.; Hirst, A.; Larsen, S.; Legendre, L.; Platt, T.; Prentice, I. C.; Rivkin, R. B.; Sathyendranath, S.; Stephens, N.; Vogt, M.; Sailley, S.; Vallina, S. M.

    2015-07-01

    Global ocean biogeochemistry models currently employed in climate change projections use highly simplified representations of pelagic food webs. These food webs do not necessarily include critical pathways by which ecosystems interact with ocean biogeochemistry and climate. Here we present a global biogeochemical model which incorporates ecosystem dynamics based on the representation of ten plankton functional types (PFTs); six types of phytoplankton, three types of zooplankton, and heterotrophic bacteria. We improved the representation of zooplankton dynamics in our model through (a) the explicit inclusion of large, slow-growing zooplankton, and (b) the introduction of trophic cascades among the three zooplankton types. We use the model to quantitatively assess the relative roles of iron vs. grazing in determining phytoplankton biomass in the Southern Ocean High Nutrient Low Chlorophyll (HNLC) region during summer. When model simulations do not represent crustacean macrozooplankton grazing, they systematically overestimate Southern Ocean chlorophyll biomass during the summer, even when there was no iron deposition from dust. When model simulations included the developments of the zooplankton component, the simulation of phytoplankton biomass improved and the high chlorophyll summer bias in the Southern Ocean HNLC region largely disappeared. Our model results suggest that the observed low phytoplankton biomass in the Southern Ocean during summer is primarily explained by the dynamics of the Southern Ocean zooplankton community rather than iron limitation. This result has implications for the representation of global biogeochemical cycles in models as zooplankton faecal pellets sink rapidly and partly control the carbon export to the intermediate and deep ocean.

  11. Global Observations and Understanding of the General Circulation of the Oceans

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The workshop was organized to: (1) assess the ability to obtain ocean data on a global scale that could profoundly change our understanding of the circulation; (2) identify the primary and secondary elements needed to conduct a World Ocean Circulation Experiment (WOCE); (3) if the ability is achievable, to determine what the U.S. role in such an experiment should be; and (4) outline the steps necessary to assure that an appropriate program is conducted. The consensus of the workshop was that a World Ocean Circulation Experiment appears feasible, worthwhile, and timely. Participants did agree that such a program should have the overall goal of understanding the general circulation of the global ocean well enough to be able to predict ocean response and feedback to long-term changes in the atmosphere. The overall goal, specific objectives, and recommendations for next steps in planning such an experiment are included.

  12. The role of clouds and oceans in global greenhouse warming. Part 1, Progress report

    SciTech Connect

    Hoffert, M.I.

    1992-12-01

    During the past three years we have conducted several studies using models and a combination of satellite data, in situ meteorological and oceanic data, and paleoclimate reconstructions, under the DoE program, ``Quantifying the Link Between Change in Radiative Balance and Atmospheric Temperature``. Our goals were to investigate effects of global cloudiness variations on global climate and their implications for cloud feedback and continue development and application of NYU transient climate/ocean models, with emphasis on coupled effects of greenhouse warming and feedbacks by both the clouds and oceans. Our original research plan emphasized the use of cloud, surface temperature and ocean data sets interpreted by focused climate/ocean models to develop a cloud radiative forcing scenario for the past 100 years and to assess the transient climate response; to narrow key uncertainties in the system; and to identify those aspects of the climate system most likely to be affected by greenhouse warming over short, medium and long time scales.

  13. How well-connected is the surface of the global ocean?

    NASA Astrophysics Data System (ADS)

    Froyland, Gary; Stuart, Robyn M.; van Sebille, Erik

    2014-09-01

    The Ekman dynamics of the ocean surface circulation is known to contain attracting regions such as the great oceanic gyres and the associated garbage patches. Less well-known are the extents of the basins of attractions of these regions and how strongly attracting they are. Understanding the shape and extent of the basins of attraction sheds light on the question of the strength of connectivity of different regions of the ocean, which helps in understanding the flow of buoyant material like plastic litter. Using short flow time trajectory data from a global ocean model, we create a Markov chain model of the surface ocean dynamics. The surface ocean is not a conservative dynamical system as water in the ocean follows three-dimensional pathways, with upwelling and downwelling in certain regions. Using our Markov chain model, we easily compute net surface upwelling and downwelling, and verify that it matches observed patterns of upwelling and downwelling in the real ocean. We analyze the Markov chain to determine multiple attracting regions. Finally, using an eigenvector approach, we (i) identify the five major ocean garbage patches, (ii) partition the ocean into basins of attraction for each of the garbage patches, and (iii) partition the ocean into regions that demonstrate transient dynamics modulo the attracting garbage patches.

  14. How well-connected is the surface of the global ocean?

    PubMed

    Froyland, Gary; Stuart, Robyn M; van Sebille, Erik

    2014-09-01

    The Ekman dynamics of the ocean surface circulation is known to contain attracting regions such as the great oceanic gyres and the associated garbage patches. Less well-known are the extents of the basins of attractions of these regions and how strongly attracting they are. Understanding the shape and extent of the basins of attraction sheds light on the question of the strength of connectivity of different regions of the ocean, which helps in understanding the flow of buoyant material like plastic litter. Using short flow time trajectory data from a global ocean model, we create a Markov chain model of the surface ocean dynamics. The surface ocean is not a conservative dynamical system as water in the ocean follows three-dimensional pathways, with upwelling and downwelling in certain regions. Using our Markov chain model, we easily compute net surface upwelling and downwelling, and verify that it matches observed patterns of upwelling and downwelling in the real ocean. We analyze the Markov chain to determine multiple attracting regions. Finally, using an eigenvector approach, we (i) identify the five major ocean garbage patches, (ii) partition the ocean into basins of attraction for each of the garbage patches, and (iii) partition the ocean into regions that demonstrate transient dynamics modulo the attracting garbage patches. PMID:25273206

  15. Trends and drivers in global surface ocean pH over the past 3 decades

    NASA Astrophysics Data System (ADS)

    Lauvset, S. K.; Gruber, N.; Landschützer, P.; Olsen, A.; Tjiputra, J.

    2015-03-01

    We report global long-term trends in surface ocean pH using a new pH data set computed by combining fCO2 observations from the Surface Ocean CO2 Atlas (SOCAT) version 2 with surface alkalinity estimates based on temperature and salinity. Trends were determined over the periods 1981-2011 and 1991-2011 for a set of 17 biomes using a weighted linear least squares method. We observe significant decreases in surface ocean pH in ~70% of all biomes and a mean rate of decrease of 0.0018 ± 0.0004 yr-1 for 1991-2011. We are not able to calculate a global trend for 1981-2011 because too few biomes have enough data for this. In half the biomes, the rate of change is commensurate with the trends expected based on the assumption that the surface ocean pH change is only driven by the surface ocean CO2 chemistry remaining in a transient equilibrium with the increase in atmospheric CO2. In the remaining biomes, deviations from such equilibrium may reflect that the trend of surface ocean fCO2 is not equal to that of the atmosphere, most notably in the equatorial Pacific Ocean, or may reflect changes in the oceanic buffer (Revelle) factor. We conclude that well-planned and long-term sustained observational networks are key to reliably document the ongoing and future changes in ocean carbon chemistry due to anthropogenic forcing.

  16. Global diversity and oceanic divergence of humpback whales (Megaptera novaeangliae).

    PubMed

    Jackson, Jennifer A; Steel, Debbie J; Beerli, P; Congdon, Bradley C; Olavarría, Carlos; Leslie, Matthew S; Pomilla, Cristina; Rosenbaum, Howard; Baker, C Scott

    2014-07-01

    Humpback whales (Megaptera novaeangliae) annually undertake the longest migrations between seasonal feeding and breeding grounds of any mammal. Despite this dispersal potential, discontinuous seasonal distributions and migratory patterns suggest that humpbacks form discrete regional populations within each ocean. To better understand the worldwide population history of humpbacks, and the interplay of this species with the oceanic environment through geological time, we assembled mitochondrial DNA control region sequences representing approximately 2700 individuals (465 bp, 219 haplotypes) and eight nuclear intronic sequences representing approximately 70 individuals (3700 bp, 140 alleles) from the North Pacific, North Atlantic and Southern Hemisphere. Bayesian divergence time reconstructions date the origin of humpback mtDNA lineages to the Pleistocene (880 ka, 95% posterior intervals 550-1320 ka) and estimate radiation of current Northern Hemisphere lineages between 50 and 200 ka, indicating colonization of the northern oceans prior to the Last Glacial Maximum. Coalescent analyses reveal restricted gene flow between ocean basins, with long-term migration rates (individual migrants per generation) of less than 3.3 for mtDNA and less than 2 for nuclear genomic DNA. Genetic evidence suggests that humpbacks in the North Pacific, North Atlantic and Southern Hemisphere are on independent evolutionary trajectories, supporting taxonomic revision of M. novaeangliae to three subspecies. PMID:24850919

  17. The Global Ocean Data Analysis Project version 2 (GLODAPv2) - an internally consistent data product for the world ocean

    NASA Astrophysics Data System (ADS)

    Olsen, Are; Key, Robert M.; van Heuven, Steven; Lauvset, Siv K.; Velo, Anton; Lin, Xiaohua; Schirnick, Carsten; Kozyr, Alex; Tanhua, Toste; Hoppema, Mario; Jutterström, Sara; Steinfeldt, Reiner; Jeansson, Emil; Ishii, Masao; Pérez, Fiz F.; Suzuki, Toru

    2016-08-01

    Version 2 of the Global Ocean Data Analysis Project (GLODAPv2) data product is composed of data from 724 scientific cruises covering the global ocean. It includes data assembled during the previous efforts GLODAPv1.1 (Global Ocean Data Analysis Project version 1.1) in 2004, CARINA (CARbon IN the Atlantic) in 2009/2010, and PACIFICA (PACIFic ocean Interior CArbon) in 2013, as well as data from an additional 168 cruises. Data for 12 core variables (salinity, oxygen, nitrate, silicate, phosphate, dissolved inorganic carbon, total alkalinity, pH, CFC-11, CFC-12, CFC-113, and CCl4) have been subjected to extensive quality control, including systematic evaluation of bias. The data are available in two formats: (i) as submitted but updated to WOCE exchange format and (ii) as a merged and internally consistent data product. In the latter, adjustments have been applied to remove significant biases, respecting occurrences of any known or likely time trends or variations. Adjustments applied by previous efforts were re-evaluated. Hence, GLODAPv2 is not a simple merging of previous products with some new data added but a unique, internally consistent data product. This compiled and adjusted data product is believed to be consistent to better than 0.005 in salinity, 1 % in oxygen, 2 % in nitrate, 2 % in silicate, 2 % in phosphate, 4 µmol kg-1 in dissolved inorganic carbon, 6 µmol kg-1 in total alkalinity, 0.005 in pH, and 5 % for the halogenated transient tracers.The original data and their documentation and doi codes are available at the Carbon Dioxide Information Analysis Center (oceans/GLODAPv2/" target="_blank">http://cdiac.ornl.gov/oceans/GLODAPv2/). This site also provides access to the calibrated data product, which is provided as a single global file or four regional ones - the Arctic, Atlantic, Indian, and Pacific oceans - under the doi:10.3334/CDIAC

  18. Accuracy assessment of the global ionospheric model over the Southern Ocean based on dynamic observation

    NASA Astrophysics Data System (ADS)

    Luo, xiaowen

    2016-04-01

    The global ionospheric model based on the reference stations of the Global Navigation Satellite System (GNSS) of the International GNSS Services is presently the most commonly used products of the global ionosphere. It is very important to comprehensively analyze and evaluate the accuracy and reliability of the model for the reasonable use of this kind of ionospheric product. This work is different to the traditional performance evaluation of the global ionosphere model based on observation data of ground-based static reference stations. The preliminary evaluation and analysis of the the global ionospheric model was conducted with the dynamic observation data across different latitudes over the southern oceans. The validation results showed that the accuracy of the global ionospheric model over the southern oceans is about 5 TECu, which deviates from the measured ionospheric TEC by about -0.6 TECu.

  19. Sea level ECV quality assessment via global ocean model assimilation

    NASA Astrophysics Data System (ADS)

    Scharffenberg, Martin; Köhl, Armin; Stammer, Detlef

    2015-04-01

    In the ocean modeling community satellite data, especially SSH fields, are assimilated on a regular basis. SSH fields are very important in this context because of their dynamical relevance for constraining the ocean's flow field. However, assimilating SSH data into an ocean model does not only improve the quality of model but in addition, can also help testing the quality and the consistency of the input data as well. In our work we aim to quantify improvements in Sea Level (SL) data through the ESA - Climate Change Initiative (cci) effort and we aim to test the consistency of the Essential Climate Variable (ECV) of Sea Level (SL_ECV) with other ECVs through the assimilation process and to investigate where remaining inconsistencies exist and why. For this purpose the GECCO2 assimilation approach assimilates SSH jointly with in situ data over the ocean. The dynamically consistent ocean state estimation adjusts only uncertain model parameters to bring the model into consistency with ocean observations. Improvements in data products can be investigated by studying the residuals between the different data products and the constrained model. PHASE 1: With this approach we could demonstrate, that in many regions the SL_ECV has been improved from version V0 (AVISO product) to version V1 (SL_cci product). However, there are regions where SL_ECV_V1 is further away from the model "truth". In that sense it is important to understand that the model assimilated SL_ECV_V0 (origianl AVISO product) and therefore has tried to adapt to the SL_ECV_V0. Therefore, inconsistencies existed when comparing the synthesis results to the updated version SL_ECV_V1! These deviations between the model "truth" and the improved data product (SL_ECV_V1) increased mostly in low energetic areas. PHASE 2: Two GECCO2-assimilation-runs (5 additional iterations) have been performed to date: 1) assimilating the original AVISO SL-product (V0) and 2) assimilating the updated-improved sea level estimate

  20. Global coupling and decoupling of the APS storage ring

    SciTech Connect

    Chae, Yong-Chul; Liu, Jianyang; Teng, L.C.

    1995-07-01

    This Paper describes a study of controlling the coupling between the horizontal and the vertical betatron oscillations in the APS storage ring. First, we investigate the strengthening of coupling using two families of skew quadrupoles. Using smooth approximation, we obtained the formulae to estimate the coupling ratio defined as the ratio of the vertical and horizontal emittances or, for a single particle, the ratio of the maximum values of the Courant Snyder invariants. Since we knew that the coupling is mostly enhanced by the 21st harmonic content of skew quadrupole distribution, we carried out the harmonic analysis in order to find the optimum arrangement of the skew quadrupoles. The numerical results from tracking a single particle are presented for the various configurations of skew quadrupoles. Second, we describe the global decoupling procedure to minimize the unwanted coupling effects. These are mainly due to the random roll errors of normal quadrupoles. It is shown that even with the rather large rms roll error of 2 mrad we can reduce the Coupling from 70 percent to 10 percent with a skew quadrupole strength which is one order of magnitude lower than the typical normal quadrupole strength.

  1. Seasonal Distributions of Global Ocean Chlorophyll and Nutrients: Analysis with a Coupled Ocean General Circulation Biogeochemical, and Radiative Model

    NASA Technical Reports Server (NTRS)

    Gregg, Watson W.

    1999-01-01

    A coupled general ocean circulation, biogeochemical, and radiative model was constructed to evaluate and understand the nature of seasonal variability of chlorophyll and nutrients in the global oceans. The model is driven by climatological meteorological conditions, cloud cover, and sea surface temperature. Biogeochemical processes in the model are determined from the influences of circulation and turbulence dynamics, irradiance availability, and the interactions among three functional phytoplankton groups (diatoms, chorophytes, and picoplankton) and three nutrient groups (nitrate, ammonium, and silicate). Phytoplankton groups are initialized as homogeneous fields horizontally and vertically, and allowed to distribute themselves according to the prevailing conditions. Basin-scale model chlorophyll results are in very good agreement with CZCS pigments in virtually every global region. Seasonal variability observed in the CZCS is also well represented in the model. Synoptic scale (100-1000 km) comparisons of imagery are also in good conformance, although occasional departures are apparent. Agreement of nitrate distributions with in situ data is even better, including seasonal dynamics, except for the equatorial Atlantic. The good agreement of the model with satellite and in situ data sources indicates that the model dynamics realistically simulate phytoplankton and nutrient dynamics on synoptic scales. This is especially true given that initial conditions are homogenous chlorophyll fields. The success of the model in producing a reasonable representation of chlorophyll and nutrient distributions and seasonal variability in the global oceans is attributed to the application of a generalized, processes-driven approach as opposed to regional parameterization, and the existence of multiple phytoplankton groups with different physiological and physical properties. These factors enable the model to simultaneously represent the great diversity of physical, biological

  2. Environmental Assessment for Potential Impacts of Ocean CO2 Storage on Marine Biogeochemical Cycles

    NASA Astrophysics Data System (ADS)

    Yamada, N.; Tsurushima, N.; Suzumura, M.; Shibamoto, Y.; Harada, K.

    2008-12-01

    Ocean CO2 storage that actively utilizes the ocean potential to dissolve extremely large amounts of CO2 is a useful option with the intent of diminishing atmospheric CO2 concentration. CO2 storage into sub-seabed geological formations is also considered as the option which has been already put to practical reconnaissance in some projects. Direct release of CO2 in the ocean storage and potential CO2 leakage from geological formations into the bottom water can alter carbonate system as well as pH of seawater. It is essential to examine to what direction and extent chemistry change of seawater induced by CO2 can affect the marine environments. Previous studies have shown direct and acute effects by increasing CO2 concentrations on physiology of marine organisms. It is also a serious concern that chemistry change can affect the rates of chemical, biochemical and microbial processes in seawater resulting in significant influences on marine biogeochemical cycles of the bioelements including carbon, nutrients and trace metals. We, AIST, have conducted a series of basic researches to assess the potential impacts of ocean CO2 storage on marine biogeochemical processes including CaCO3 dissolution, and bacterial and enzymatic decomposition of organic matter. By laboratory experiments using a special high pressure apparatus, the improved empirical equation was obtained for CaCO3 dissolution rate in the high CO2 concentrations. Based on the experimentally obtained kinetics with a numerical simulation for a practical scenario of oceanic CO2 sequestration where 50 Mton CO2 per year is continuously injected to 1,000-2,500 m depth within 100 x 333 km area for 30 years, we could illustrate precise 3-D maps for the predicted distributions of the saturation depth of CaCO3, in situ Ω value and CaCO3 dissolution rate in the western North Pacific. The result showed no significant change in the bathypelagic CaCO3 flux due to chemistry change induced by ocean CO2 sequestration. Both

  3. Assessment of Global Oceanic Net Freshwater Flux Products Using Argo Salinity Observations

    NASA Astrophysics Data System (ADS)

    Ren, L.; Arkin, P. A.; Hackert, E. C.; Busalacchi, A. J.

    2012-12-01

    The annual mean global upper ocean salt budget is investigated using the Argo profiling float data from 2006 to 2011, which provides a way to estimate the annual mean oceanic evaporation and precipitation (E-P) from the ocean salinity. Employing this "ocean rain gauge" concept, E-P estimated from the salt budget is compared with the various satellite based oceanic precipitation and evaporation observational products. In this study, twelve sets of E-P from the evaporation and precipitation products including the precipitation datasets GPCP, CMAP and TRMM and the evaporation datasets OAFlux, GSSTF2b, IFREMER and RSS are compared to the E-P estimated from the salinity. We will describe the spatial patterns of the various E-P products derived from the satellite based data sets and compare these patterns to those derived from the oceanic salinity on the annual mean time scale. We will also examine time series of near-global integrated E-P derived from satellite products and compare them to time series based on oceanic salinity observations as well as continental discharge. This intercomparison of independently derived estimates of fresh water flux at the ocean surface will improve our understanding of errors in remotely sensed estimates of evaporation and precipitation.

  4. Global Ocean Circulation Modeling with an Isopycnic Coordinate Model. Final Report for May 1, 1998 - April 30, 2002

    SciTech Connect

    Bleck, R.

    2004-05-19

    The overall aim of this project was to continue development of a global version of the Miami Isopycnic Coordinate Ocean Model (MICOM) with the intent of turning it into a full-fledged oceanic component of an earth system model.

  5. Digital Global Map of Potential Ocean Paleoshorelines on Mars

    NASA Astrophysics Data System (ADS)

    Parker, T. J.; Calef, F. J.

    2012-05-01

    Our objective is to compile a global shoreline map, in the form of GIS shapefiles. This map will be used to investigate deviations from horizontal that might indicate neotectonic changes such as mass accumulations and crustal deformations over time.

  6. Total Human-Caused Global Ocean Heat Uptake Nearly Doubles During Recent Surface Warming Hiatus

    NASA Astrophysics Data System (ADS)

    Gleckler, P. J.; Durack, P. J.; Stouffer, R. J.; Johnson, G. C.; Forest, C. E.

    2015-12-01

    Formal detection and attribution studies have used observations and climate models to identify an anthropogenic warming signature in the upper (0­-700 m) ocean. Recently, as a result of the so-called surface warming hiatus, there has been considerable interest in global ocean heat content (OHC) changes in the deeper ocean, including natural and anthropogenically forced changes evidenced in observational, modelling, and data re-analysis studies. We rely on OHC change estimates from a diverse collection of measurement systems including data from the 19th Century Challenger expedition, a multi-decadal record of ship-based in-situ mostly upper ocean measurements, the more recent near-global Argo floats profiling to intermediate (2000m) depths, and full-depth repeated transoceanic sections. By diagnosing simulated global OHC changes in historically-forced climate models in three depth layers, we show that the current generation of climate models is broadly consistent with multi-decadal estimates of upper, intermediate (700­-2000m) and deep (2000m - ­bottom) global OHC changes as well as with Argo-based estimates over the most recent period. Our results suggest that nearly half of the 1860-­present human-caused increases in global ocean heat content may have occurred since 1998.

  7. How well will the Surface Water and Ocean Topography (SWOT) mission observe global reservoirs?

    NASA Astrophysics Data System (ADS)

    Solander, Kurt C.; Reager, John T.; Famiglietti, James S.

    2016-03-01

    Accurate observations of global reservoir storage are critical to understand the availability of managed water resources. By enabling estimates of surface water area and height for reservoir sizes exceeding 250 m2 at a maximum repeat orbit of up to 21 days, the NASA Surface Water and Ocean Topography (SWOT) satellite mission (anticipated launch date 2020) is expected to greatly improve upon existing reservoir monitoring capabilities. It is thus essential that spatial and temporal measurement uncertainty for water bodies is known a priori to maximize the utility of SWOT observations as the data are acquired. In this study, we evaluate SWOT reservoir observations using a three-pronged approach that assesses temporal aliasing, errors due to specific reservoir spatial properties, and SWOT performance over actual reservoirs using a combination of in situ and simulated reservoir observations from the SWOTsim instrument simulator. Results indicate temporal errors to be less than 5% for the smallest reservoir sizes (< 10 km2) with errors less than 0.1% for larger sizes (>100 km2). Surface area and height errors were found to be minimal (area <5%, height <15 cm) above 1 km2 unless the reservoir exhibited a strong elliptical shape with high aspect ratio oriented parallel to orbit, was set in mountainous terrain, or swath coverage fell below 30%. Experiments from six real reservoir test cases generally support these results. By providing a comprehensive blueprint on the observability of reservoirs from SWOT, this study will be have important implications for future applications of SWOT reservoir measurements in global monitoring systems and models.

  8. Total Land Water Storage Change over 2003 - 2013 Estimated from a Global Mass Budget Approach

    NASA Technical Reports Server (NTRS)

    Dieng, H. B.; Champollion, N.; Cazenave, A.; Wada, Y.; Schrama, E.; Meyssignac, B.

    2015-01-01

    We estimate the total land water storage (LWS) change between 2003 and 2013 using a global water mass budget approach. Hereby we compare the ocean mass change (estimated from GRACE space gravimetry on the one hand, and from the satellite altimetry-based global mean sea level corrected for steric effects on the other hand) to the sum of the main water mass components of the climate system: glaciers, Greenland and Antarctica ice sheets, atmospheric water and LWS (the latter being the unknown quantity to be estimated). For glaciers and ice sheets, we use published estimates of ice mass trends based on various types of observations covering different time spans between 2003 and 2013. From the mass budget equation, we derive a net LWS trend over the study period. The mean trend amounts to +0.30 +/- 0.18 mm/yr in sea level equivalent. This corresponds to a net decrease of -108 +/- 64 cu km/yr in LWS over the 2003-2013 decade. We also estimate the rate of change in LWS and find no significant acceleration over the study period. The computed mean global LWS trend over the study period is shown to be explained mainly by direct anthropogenic effects on land hydrology, i.e. the net effect of groundwater depletion and impoundment of water in man-made reservoirs, and to a lesser extent the effect of naturally-forced land hydrology variability. Our results compare well with independent estimates of human-induced changes in global land hydrology.

  9. Total land water storage change over 2003-2013 estimated from a global mass budget approach

    NASA Astrophysics Data System (ADS)

    Dieng, H. B.; Champollion, N.; Cazenave, A.; Wada, Y.; Schrama, E.; Meyssignac, B.

    2015-12-01

    We estimate the total land water storage (LWS) change between 2003 and 2013 using a global water mass budget approach. Hereby we compare the ocean mass change (estimated from GRACE space gravimetry on the one hand, and from the satellite altimetry-based global mean sea level corrected for steric effects on the other hand) to the sum of the main water mass components of the climate system: glaciers, Greenland and Antarctica ice sheets, atmospheric water and LWS (the latter being the unknown quantity to be estimated). For glaciers and ice sheets, we use published estimates of ice mass trends based on various types of observations covering different time spans between 2003 and 2013. From the mass budget equation, we derive a net LWS trend over the study period. The mean trend amounts to +0.30 ± 0.18 mm yr-1 in sea level equivalent. This corresponds to a net decrease of -108 ± 64 km3 yr-1 in LWS over the 2003-2013 decade. We also estimate the rate of change in LWS and find no significant acceleration over the study period. The computed mean global LWS trend over the study period is shown to be explained mainly by direct anthropogenic effects on land hydrology, i.e. the net effect of groundwater depletion and impoundment of water in man-made reservoirs, and to a lesser extent the effect of naturally-forced land hydrology variability. Our results compare well with independent estimates of human-induced changes in global land hydrology.

  10. Total land water storage change over 2003-2013 estimated from a global mass budget approach

    NASA Astrophysics Data System (ADS)

    Dieng, Habib B.; Champollion, Nicolas; Cazenave, Anny; Wada, Yoshihide; Schrama, Ernst; Meyssignac, Benoit

    2016-04-01

    We estimate the total land water storage (LWS) change between 2003 and 2013 using a global water mass budget approach. Hereby we compare the ocean mass change (estimated from GRACE space gravimetry on the one hand, and from the satellite altimetry-based global mean sea level corrected for steric effects on the other hand) to the sum of the main water mass components of the climate system: glaciers, Greenland and Antarctica ice sheets, atmospheric water and LWS(the latter being the unknown quantity to be estimated). For glaciers and ice sheets, we use published estimates of ice mass trends based on various types of observations covering different time spans between 2003 and 2013. From the mass budget equation, we derive a net LWS trend over the study period. The mean trend amounts to+0.30 ± 0.18mmyr‑1 in sea level equivalent. This corresponds to a net decrease of ‑108 ± 64 km3 yr‑1 in LWS over the 2003-2013 decade. We also estimate the rate of change in LWS and find no significant acceleration over the study period. The computed mean global LWS trend over the study period is shown to be explained mainly by direct anthropogenic effects on land hydrology, i.e. the net effect of groundwater depletion and impoundment of water in man-made reservoirs, and to a lesser extent the effect of naturally-forced land hydrology variability. Our results compare well with independent estimates of human-induced changes in global land hydrology.

  11. Constraints on the transient climate response from observed global temperature and ocean heat uptake

    NASA Astrophysics Data System (ADS)

    Knutti, Reto; Tomassini, Lorenzo

    2008-05-01

    Projections of future transient global temperature increase in climate models for a known forcing depend on the strength of the atmospheric feedbacks and the rate of transient ocean heat uptake. A Bayesian framework and an intermediate complexity climate model are used to calculate a probability density function (PDF) of the transient climate response (TCR), constrained by observations of global surface warming and ocean heat uptake. The PDF constrained by observations is wider than the TCR range of current climate models, and has a slightly lower mean. Uncertainties in the observed ocean warming are shown to potentially affect the TCR. It is proposed, however, that even if models were found to overestimate ocean heat uptake, correcting that bias would lead to revisions in surface temperature projections over the twenty-first century that are smaller than the uncertainties introduced by poorly quantified atmospheric feedbacks.

  12. Oceanic primary production: 2. Estimation at global scale from satellite (coastal zone color scanner) chlorophyll

    SciTech Connect

    Antione, D.; Andre, J.M.; Morel, A.

    1996-03-01

    The purpose of this study was to assess the oceanic seasonal evolution and spatial distribution of photosynthetic carbon fixation. Computation of primary production from the upper ocean chlorophyll-like pigment concentrations were made from monthly global maps from the coastal zone color scanner data archive. Relative contributions of various oceans and zonal belts were identified. Depending on the ratio used for active pigments to total pigments, the calculated global annual production ranges from 36.5 and 45.6 G tons (metric) carbon per year. These values are among the highest estimates proposed to date; although the absolute values may be somewhat questionable, the relative contribution of the various zonal belts and oceans are considered to have a high degree of accuracy. 33 refs., 4 figs., 2 tabs.

  13. Global patterns of changes in underwater sound transmission caused by ocean acidification

    NASA Astrophysics Data System (ADS)

    Ilyina, T.; Zeebe, R. E.; Brewer, P. G.

    2009-04-01

    Oceanic uptake of man-made CO2 leads to a decrease in the ocean pH and carbonate saturation state. This processes, known as ocean acidification is expected to have adverse effects on a variety of marine organisms. A surprising consequence of ocean acidification, which has gone widely unrecognized, is its effect on underwater sound transmission. Low-frequency sound absorption in the ocean occurs due to chemical relaxation of the pH-dependent boric acid-borate ion reaction. As ocean pH drops, sound absorption in the audible range decreases. The decreased sound absorption will amplify ambient noise levels, and enhance long distance sound transmission, although its exact environmental impact is uncertain. Changes in the underwater sound absorption will affect the operation of scientific, commercial, and naval applications that are based on ocean acoustics, with yet unknown consequences for marine life. We project these changes using a global biogeochemical model (HAMOCC), which is forced by the anthropogenic CO2 emissions during the years 1800-2300. Based on model projections, we quantify when and where in the ocean these ocean chemistry induced perturbations in sound absorption will occur.

  14. Cycling of DDT in the global environment 1950-2002: World ocean returns the pollutant

    NASA Astrophysics Data System (ADS)

    Stemmler, Irene; Lammel, Gerhard

    2009-12-01

    The global distribution and fate of the insecticide DDT was modeled for the first time using a spatially resolved global multicompartment chemistry-transport model comprising a 3D coupled atmosphere and ocean GCM, coupled to 2D vegetation surfaces and top soils. DDT enters the model environment as a pesticide in agriculture only. Final sinks of DDT in the total environment are degradation in air (hydroxyl radical reaction), on vegetation surfaces, in ocean sediments and soils. The process resolution of the ocean compartment, i.e., either a fixed or variable size and sinking velocity of suspended particles, has almost no effect on the large-scale cycling and fate of DDT. The residence times in various ocean basins were declining but varied regionally. The global ocean absorbed until 1977 and since then has been losing DDT, while large sea areas are still accumulating the pollutant. The main sink is volatilization to the atmosphere. In 1990, the year when emissions ceased, 292 kt of DDT were deposited to the global ocean, 301 kt were volatilized, and 41 kt were exported from the surface layer to the deeper levels. The sea region that has been representing the most significant (secondary) DDT source is the western N Atlantic (Gulf stream and N Atlantic Drift regions). It has been a source since approximately 1970. Also large parts of the tropical ocean and the southern mid-latitude ocean have turned net volatilizational (i.e., volatilization flux > deposition flux) during the 1980s. Despite the emissions migrating southward as a consequence of substance ban in mid latitudes, the geographic distribution of the contaminant (and, hence, environmental exposure) has been migrating steadily northward since the 1960s.

  15. Assessment of Global Forecast Ocean Assimilation Model (FOAM) using new satellite SST data

    NASA Astrophysics Data System (ADS)

    Ascione Kenov, Isabella; Sykes, Peter; Fiedler, Emma; McConnell, Niall; Ryan, Andrew; Maksymczuk, Jan

    2016-04-01

    There is an increased demand for accurate ocean weather information for applications in the field of marine safety and navigation, water quality, offshore commercial operations, monitoring of oil spills and pollutants, among others. The Met Office, UK, provides ocean forecasts to customers from governmental, commercial and ecological sectors using the Global Forecast Ocean Assimilation Model (FOAM), an operational modelling system which covers the global ocean and runs daily, using the NEMO (Nucleus for European Modelling of the Ocean) ocean model with horizontal resolution of 1/4° and 75 vertical levels. The system assimilates salinity and temperature profiles, sea surface temperature (SST), sea surface height (SSH), and sea ice concentration observations on a daily basis. In this study, the FOAM system is updated to assimilate Advanced Microwave Scanning Radiometer 2 (AMSR2) and the Spinning Enhanced Visible and Infrared Imager (SEVIRI) SST data. Model results from one month trials are assessed against observations using verification tools which provide a quantitative description of model performance and error, based on statistical metrics, including mean error, root mean square error (RMSE), correlation coefficient, and Taylor diagrams. A series of hindcast experiments is used to run the FOAM system with AMSR2 and SEVIRI SST data, using a control run for comparison. Results show that all trials perform well on the global ocean and that largest SST mean errors were found in the Southern hemisphere. The geographic distribution of the model error for SST and temperature profiles are discussed using statistical metrics evaluated over sub-regions of the global ocean.

  16. A Global, Multi-Resolution Approach to Regional Ocean Modeling

    SciTech Connect

    Du, Qiang

    2013-11-08

    In this collaborative research project between Pennsylvania State University, Colorado State University and Florida State University, we mainly focused on developing multi-resolution algorithms which are suitable to regional ocean modeling. We developed hybrid implicit and explicit adaptive multirate time integration method to solve systems of time-dependent equations that present two signi cantly di erent scales. We studied the e ects of spatial simplicial meshes on the stability and the conditioning of fully discrete approximations. We also studies adaptive nite element method (AFEM) based upon the Centroidal Voronoi Tessellation (CVT) and superconvergent gradient recovery. Some of these techniques are now being used by geoscientists(such as those at LANL).

  17. Remote sensing of oceanic biology in relation to global climate change

    SciTech Connect

    Aiken, J.; Moore, G.F.; Holligan, P.M. )

    1992-10-01

    The oceans have a fundamental role in the global climate system because of their capacity to store and transport heat and absorb and emit trace gases which affect the earth's radiation budget. Although good progress has been made with issues such as carbon and sulfur cycling, feedback responses related to the impact of climate change on biological systems, and links between plankton ecology and climate, there is a lack of information on the distributions of biological properties on a global scale. This article reviews the potential contribution of ocean color measurements for biological studies within the context of climate change. The remote sensing of oceanic phytoplankton from satellites measuring radiance at visible and near infrared wavelenghts has produced a wealth of new information on biomass distributions and has provided a basis for new approaches to estimation of global marine primary productivity.

  18. The role of clouds and oceans in global greenhouse warming. Final report

    SciTech Connect

    Hoffert, M.I.

    1996-10-01

    This research focuses on assessing connections between anthropogenic greenhouse gas emissions and global climatic change. it has been supported since the early 1990s in part by the DOE ``Quantitative Links`` Program (QLP). A three-year effort was originally proposed to the QLP to investigate effects f global cloudiness on global climate and its implications for cloud feedback; and to continue the development and application of climate/ocean models, with emphasis on coupled effects of greenhouse warming and feedbacks by clouds and oceans. It is well-known that cloud and ocean processes are major sources of uncertainty in the ability to predict climatic change from humankind`s greenhouse gas and aerosol emissions. And it has always been the objective to develop timely and useful analytical tools for addressing real world policy issues stemming from anthropogenic climate change.

  19. Global representation of tropical cyclone-induced short-term ocean thermal changes using Argo data

    NASA Astrophysics Data System (ADS)

    Cheng, L.; Zhu, J.; Sriver, R. L.

    2015-09-01

    Argo floats are used to examine tropical cyclone (TC) induced ocean thermal changes on the global scale by comparing temperature profiles before and after TC passage. We present a footprint method that analyzes cross-track thermal responses along all storm tracks during the period 2004-2012. We combine the results into composite representations of the vertical structure of the average thermal response for two different categories: tropical storms/tropical depressions (TS/TD) and hurricanes. The two footprint composites are functions of three variables: cross-track distance, water depth and time relative to TC passage. We find that this footprint strategy captures the major features of the upper-ocean thermal response to TCs on timescales up to 20 days when compared against previous case study results using in situ measurements. On the global scale, TCs are responsible for 1.87 PW (11.05 W m-2) of heat transfer annually from the global ocean to the atmosphere during storm passage (0-3 days). Of this total, 1.05 ± 0.20 PW (4.80 ± 0.85 W m-2) is caused by TS/TD and 0.82 ± 0.21 PW (6.25 ± 1.5 W m-2) is caused by hurricanes. Our findings indicate that ocean heat loss by TCs may be a substantial missing piece of the global ocean heat budget. Changes in ocean heat content (OHC) after storm passage are estimated by analyzing the temperature anomalies during wake recovery following storm events (4-20 days after storm passage) relative to pre-storm conditions. Results indicate the global ocean experiences a 0.75 ± 0.25 PW (5.98 ± 2.1 W m-2) heat gain annually for hurricanes. In contrast, under TS/TD conditions, the ocean experiences 0.41 ± 0.21 PW (1.90 ± 0.96 W m-2) ocean heat loss, suggesting the overall oceanic thermal response is particularly sensitive to the intensity of the event. The ocean heat uptake caused by all storms during the restorative stage is 0.34 PW.

  20. Low-frequency variability of sea level as related to the heat balance of global oceans

    NASA Technical Reports Server (NTRS)

    Liu, W. Timothy; Niiler, P.; Patzert, W.

    1991-01-01

    The TOPEX/POSEIDON mission will determine global changes of sea level with unprecedented accuracy. Our main objective is the use TOPEX/POSEIDON data, concurrent in situ ocean measurements, and other satellite observations to document and diagnose physical processes by which heat is exchanged with the atmosphere, stored in the ocean, or transported by ocean circulation. During the prelaunch period, our objectives are to advise the project on an improved method of retrieving sea level data and prepare for the application of TOPEX/POSEIDON data by developing a diagnostic model using in situ measurements and altimeter observations from Geosat and the European Remote Sensing satellite.

  1. Insights into global diatom distribution and diversity in the world's ocean.

    PubMed

    Malviya, Shruti; Scalco, Eleonora; Audic, Stéphane; Vincent, Flora; Veluchamy, Alaguraj; Poulain, Julie; Wincker, Patrick; Iudicone, Daniele; de Vargas, Colomban; Bittner, Lucie; Zingone, Adriana; Bowler, Chris

    2016-03-15

    Diatoms (Bacillariophyta) constitute one of the most diverse and ecologically important groups of phytoplankton. They are considered to be particularly important in nutrient-rich coastal ecosystems and at high latitudes, but considerably less so in the oligotrophic open ocean. The Tara Oceans circumnavigation collected samples from a wide range of oceanic regions using a standardized sampling procedure. Here, a total of ∼12 million diatom V9-18S ribosomal DNA (rDNA) ribotypes, derived from 293 size-fractionated plankton communities collected at 46 sampling sites across the global ocean euphotic zone, have been analyzed to explore diatom global diversity and community composition. We provide a new estimate of diversity of marine planktonic diatoms at 4,748 operational taxonomic units (OTUs). Based on the total assigned ribotypes, Chaetoceros was the most abundant and diverse genus, followed by Fragilariopsis, Thalassiosira, and Corethron We found only a few cosmopolitan ribotypes displaying an even distribution across stations and high abundance, many of which could not be assigned with confidence to any known genus. Three distinct communities from South Pacific, Mediterranean, and Southern Ocean waters were identified that share a substantial percentage of ribotypes within them. Sudden drops in diversity were observed at Cape Agulhas, which separates the Indian and Atlantic Oceans, and across the Drake Passage between the Atlantic and Southern Oceans, indicating the importance of these ocean circulation choke points in constraining diatom distribution and diversity. We also observed high diatom diversity in the open ocean, suggesting that diatoms may be more relevant in these oceanic systems than generally considered. PMID:26929361

  2. Insights into global diatom distribution and diversity in the world’s ocean

    PubMed Central

    Malviya, Shruti; Scalco, Eleonora; Audic, Stéphane; Vincent, Flora; Veluchamy, Alaguraj; Poulain, Julie; Wincker, Patrick; Iudicone, Daniele; de Vargas, Colomban; Bittner, Lucie; Zingone, Adriana; Bowler, Chris

    2016-01-01

    Diatoms (Bacillariophyta) constitute one of the most diverse and ecologically important groups of phytoplankton. They are considered to be particularly important in nutrient-rich coastal ecosystems and at high latitudes, but considerably less so in the oligotrophic open ocean. The Tara Oceans circumnavigation collected samples from a wide range of oceanic regions using a standardized sampling procedure. Here, a total of ∼12 million diatom V9-18S ribosomal DNA (rDNA) ribotypes, derived from 293 size-fractionated plankton communities collected at 46 sampling sites across the global ocean euphotic zone, have been analyzed to explore diatom global diversity and community composition. We provide a new estimate of diversity of marine planktonic diatoms at 4,748 operational taxonomic units (OTUs). Based on the total assigned ribotypes, Chaetoceros was the most abundant and diverse genus, followed by Fragilariopsis, Thalassiosira, and Corethron. We found only a few cosmopolitan ribotypes displaying an even distribution across stations and high abundance, many of which could not be assigned with confidence to any known genus. Three distinct communities from South Pacific, Mediterranean, and Southern Ocean waters were identified that share a substantial percentage of ribotypes within them. Sudden drops in diversity were observed at Cape Agulhas, which separates the Indian and Atlantic Oceans, and across the Drake Passage between the Atlantic and Southern Oceans, indicating the importance of these ocean circulation choke points in constraining diatom distribution and diversity. We also observed high diatom diversity in the open ocean, suggesting that diatoms may be more relevant in these oceanic systems than generally considered. PMID:26929361

  3. The complementary role of SMOS sea surface salinity observations for estimating global ocean salinity state

    NASA Astrophysics Data System (ADS)

    Lu, Zeting; Cheng, Lijing; Zhu, Jiang; Lin, Renping

    2016-06-01

    Salinity is a key ocean state property, changes in which reveal the variation of the water cycle and the ocean thermohaline circulation. However, prior to this century, in situ salinity observations were extremely sparse, which decreased the reliability of simulations of ocean general circulation by ocean and climate models. In 2009, sea surface salinity (SSS) observations covered the global ocean via the European Space Agency's Soil Moisture and Ocean Salinity (SMOS) mission, and several versions of global SSS products were subsequently released. How can these data benefit model performance? Previous studies found contradictory results. In this work, we assimilated SMOS-SSS data into the LASG/IAP Climate system Ocean Model (LICOM) using the Ensemble Optimum Interpolation (EnOI) assimilation scheme. To assess and quantify the contribution of SMOS-SSS data to model performance, several tests were conducted. The results indicate that the CECOS/CATDS 2010.V02 SMOS-SSS product can significantly improve model simulations of sea surface/subsurface salinity fields. This study provides the basis for the future assimilation of SMOS-SSS data for short-range climate forecasting.

  4. The seasonal cycle of diabatic heat storage in the Pacific Ocean

    USGS Publications Warehouse

    White, Warren B.; Cayan, D.R.; Niiler, P.P.; Moisan, J.; Lagerloef, G.; Bonjean, F.; Legler, D.

    2005-01-01

    This study quantifies uncertainties in closing the seasonal cycle of diabatic heat storage (DHS) over the Pacific Ocean from 20??S to 60??N through the synthesis of World Ocean Circulation Experiment (WOCE) reanalysis products from 1993 to 1999. These products are DHS from Scripps Institution of Oceanography (SIO); near-surface geostrophic and Ekman currents from Earth and Space Research (ESR); and air-sea heat fluxes from Comprehensive Ocean-Atmosphere Data Set (COADS), National Centers for Environmental Prediction (NCEP), and European Center for Mid-Range Weather Forecasts (ECMWF). With these products, we compute residual heat budget components by differencing long-term monthly means from the long-term annual mean. This allows the seasonal cycle of the DHS tendency to be modeled. Everywhere latent heat flux residuals dominate sensible heat flux residuals, shortwave heat flux residuals dominate longwave heat flux residuals, and residual Ekman heat advection dominates residual geostrophic heat advection, with residual dissipation significant only in the Kuroshio-Oyashio current extension. The root-mean-square (RMS) of the differences between observed and model residual DHS tendencies (averaged over 10??latitude-by-20??longitude boxes) is <20 W m-2 in the interior ocean and <100 W m-2 in the Kuroshio-Oyashio current extension. This reveals that the residual DHS tendency is driven everywhere by some mix of residual latent heat flux, shortwave heat flux, and Ekman heat advection. Suppressing bias errors in residual air-sea turbulent heat fluxes and Ekman heat advection through minimization of the RMS differences reduces the latter to <10 W m-2 over the interior ocean and <25 W m -2 in the Kuroshio-Oyashio current extension. This reveals air-sea temperature and specific humidity differences from in situ surface marine weather observations to be a principal source of bias error, overestimated over most of ocean but underestimated near the Intertropical Convergence Zone

  5. Effect of Storage Method on Spore Viability in Five Globally Threatened Fern Species

    PubMed Central

    QUINTANILLA, LUIS G.; AMIGO, JAVIER; PANGUA, EMILIA; PAJARÓN, SANTIAGO

    2002-01-01

    Spore germination of five globally threatened fern species [Culcita macrocarpa C. Presl, Dryopteris aemula (Aiton) O. Kuntze, D. corleyi Fraser‐Jenkins, D. guanchica Gibby and Jermy and Woodwardia radicans (L.) Sm.] was determined after 1, 6 or 12 months of storage in glass vials (dry storage) or on agar (wet storage) at –20, 5 or 20 °C. In all species, storage technique, storage temperature and the technique–temperature interaction all had a significant effect on germination percentage. In most cases, the germination percentage was best maintained by wet storage at 5 or 20 °C. In the case of the hygrophilous species C. macrocarpa and W. radicans, 6 or 12 months’ dry storage killed most spores. Only Woodwardia radicans germinated in the dark during wet storage at 20 °C. Wet storage at 5 °C prevented dark germination, and reduced bacterial and fungal contamination. Wet storage at –20 °C killed all or most spores in all species. In the three Dryopteris species, the differences among the storage conditions tested were smaller than in C. macrocarpa and W. radicans, and the decline in spore viability during storage was less marked, with high germination percentages being observed after 12 months of dry storage at all three temperatures. Dry storage, which has lower preparation time and space requirements than wet storage, was generally more effective at the lower temperatures (–20 or 5 °C). PMID:12324269

  6. A global seasonal surface ocean climatology of phytoplankton types based on CHEMTAX analysis of HPLC pigments

    NASA Astrophysics Data System (ADS)

    Swan, Chantal M.; Vogt, Meike; Gruber, Nicolas; Laufkoetter, Charlotte

    2016-03-01

    Much advancement has been made in recent years in field data assimilation, remote sensing and ecosystem modeling, yet our global view of phytoplankton biogeography beyond chlorophyll biomass is still a cursory taxonomic picture with vast areas of the open ocean requiring field validations. High performance liquid chromatography (HPLC) pigment data combined with inverse methods offer an advantage over many other phytoplankton quantification measures by way of providing an immediate perspective of the whole phytoplankton community in a sample as a function of chlorophyll biomass. Historically, such chemotaxonomic analysis has been conducted mainly at local spatial and temporal scales in the ocean. Here, we apply a widely tested inverse approach, CHEMTAX, to a global climatology of pigment observations from HPLC. This study marks the first systematic and objective global application of CHEMTAX, yielding a seasonal climatology comprised of ~1500 1°×1° global grid points of the major phytoplankton pigment types in the ocean characterizing cyanobacteria, haptophytes, chlorophytes, cryptophytes, dinoflagellates, and diatoms, with results validated against prior regional studies where possible. Key findings from this new global view of specific phytoplankton abundances from pigments are a) the large global proportion of marine haptophytes (comprising 32±5% of total chlorophyll), whose biogeochemical functional roles are relatively unknown, and b) the contrasting spatial scales of complexity in global community structure that can be explained in part by regional oceanographic conditions. The results are publically accessible via

  7. Weak response of oceanic dimethylsulfide to upper mixing shoaling induced by global warming.

    PubMed

    Vallina, S M; Simó, R; Manizza, M

    2007-10-01

    The solar radiation dose in the oceanic upper mixed layer (SRD) has recently been identified as the main climatic force driving global dimethylsulfide (DMS) dynamics and seasonality. Because DMS is suggested to exert a cooling effect on the earth radiative budget through its involvement in the formation and optical properties of tropospheric clouds over the ocean, a positive relationship between DMS and the SRD supports the occurrence of a negative feedback between the oceanic biosphere and climate, as postulated 20 years ago. Such a natural feedback might partly counteract anthropogenic global warming through a shoaling of the mixed layer depth (MLD) and a consequent increase of the SRD and DMS concentrations and emission. By applying two globally derived DMS diagnostic models to global fields of MLD and chlorophyll simulated with an Ocean General Circulation Model coupled to a biogeochemistry model for a 50% increase of atmospheric CO(2) and an unperturbed control run, we have estimated the response of the DMS-producing pelagic ocean to global warming. Our results show a net global increase in surface DMS concentrations, especially in summer. This increase, however, is so weak (globally 1.2%) that it can hardly be relevant as compared with the radiative forcing of the increase of greenhouse gases. This contrasts with the seasonal variability of DMS (1000-2000% summer-to-winter ratio). We suggest that the "plankton-DMS-clouds-earth albedo feedback" hypothesis is less strong a long-term thermostatic system than a seasonal mechanism that contributes to regulate the solar radiation doses reaching the earth's biosphere. PMID:17901211

  8. GLOBEC (Global Ocean Ecosystems Dynamics: Northwest Atlantic program

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The specific objective of the meeting was to plan an experiment in the Northwestern Atlantic to study the marine ecosystem and its role, together with that of climate and physical dynamics, in determining fisheries recruitment. The underlying focus of the GLOBEC initiative is to understand the marine ecosystem as it related to marine living resources and to understand how fluctuation in these resources are driven by climate change and exploitation. In this sense the goal is a solid scientific program to provide basic information concerning major fisheries stocks and the environment that sustains them. The plan is to attempt to reach this understanding through a multidisciplinary program that brings to bear new techniques as disparate as numerical fluid dynamic models of ocean circulation, molecular biology and modern acoustic imaging. The effort will also make use of the massive historical data sets on fisheries and the state of the climate in a coordinated manner.

  9. Internally Consistent MODIS Estimate of Aerosol Clear-Sky Radiative Effect Over the Global Oceans

    NASA Technical Reports Server (NTRS)

    Remer, Lorraine A.; Kaufman, Yoram J.

    2004-01-01

    Modern satellite remote sensing, and in particular the MODerate resolution Imaging Spectroradiometer (MODIS), offers a measurement-based pathway to estimate global aerosol radiative effects and aerosol radiative forcing. Over the Oceans, MODIS retrieves the total aerosol optical thickness, but also reports which combination of the 9 different aerosol models was used to obtain the retrieval. Each of the 9 models is characterized by a size distribution and complex refractive index, which through Mie calculations correspond to a unique set of single scattering albedo, assymetry parameter and spectral extinction for each model. The combination of these sets of optical parameters weighted by the optical thickness attributed to each model in the retrieval produces the best fit to the observed radiances at the top of the atmosphere. Thus the MODIS Ocean aerosol retrieval provides us with (1) An observed distribution of global aerosol loading, and (2) An internally-consistent, observed, distribution of aerosol optical models that when used in combination will best represent the radiances at the top of the atmosphere. We use these two observed global distributions to initialize the column climate model by Chou and Suarez to calculate the aerosol radiative effect at top of the atmosphere and the radiative efficiency of the aerosols over the global oceans. We apply the analysis to 3 years of MODIS retrievals from the Terra satellite and produce global and regional, seasonally varying, estimates of aerosol radiative effect over the clear-sky oceans.

  10. The effect of atmospheric nitrogen deposition on marine nitrogen cycling throughout the global ocean

    NASA Astrophysics Data System (ADS)

    Somes, Christopher; Oschlies, Andreas

    2014-05-01

    The rapidly increasing rate of anthropogenic nitrogen deposition has the potential to perturb marine ecosystems and biogeochemical cycles because nitrogen is one of the major limiting nutrients in the ocean. We use an Earth System Climate Model that includes ocean biogeochemistry to assess the impact of atmospheric nitrogen deposition. Experiments are conducted where we artificially add nitrogen to nearly all locations individually throughout the global surface ocean using a nitrogen deposition rate of 700 mg N m-2 yr-1, which is consistent with modern estimates near industrial areas. We identify oceanic "biomes" that respond differently to atmospheric nitrogen deposition. (1) When nitrogen is deposited near oxygen minimum zones where water column denitrification occurs, locally increased primary production stimulates additional denitrification. Since water column denitrification removes 7 mol N for every mol N of newly formed organic matter respired, the global oceanic nitrogen inventory declines in response to nitrogen deposition in these areas. This slow, but steady decline persists for at least 1,000 years. (2) When nitrogen is deposited above shallow continental shelves where benthic denitrification occurs, our benthic denitrification model predicts an increase that is nearly equal to the nitrogen deposited and thus no net change in the global nitrogen inventory. (3) When nitrogen is deposited into the high latitude open ocean far removed from nitrogen fixation and denitrification, all of this deposited nitrogen initially accumulates in the ocean. This nitrogen eventually circulates into the tropical oxygen minimum zones where it fuels additional primary production and denitrification, which removes nitrogen at a rate equal to the deposition after 1,000 years and leads to a stable, but increased nitrogen inventory in our model. (4) When nitrogen is deposited into the open ocean where nitrogen fixation occurs, nitrogen fixation decreases due to less nitrogen

  11. Enhancing the resolution of sea ice in a global ocean GCM

    NASA Astrophysics Data System (ADS)

    Stössel, Achim; Kim, Joong-Tae

    Open water in sea ice, such as leads and polynyas, has a considerable impact on the long-term global deep-ocean properties and circulation. Its representation in ocean general circulation models (GCMs) that are designed for studies of the long-term thermohaline circulation, however, bears large uncertainties. Here, an attempt has been made to reduce such uncertainties by enhancing the resolution of the sea-ice component, while keeping the ocean component at coarse resolution to preserve the necessary efficiency of the GCM. In this study, the higher-resolved sea-ice component has been restricted to the Southern Ocean. Compared to the original model, the new version yields more detailed structures, such as a more detailed representation of coastal polynyas, a realistically sharp ice edge, and an overall enhanced lead fraction. The latter gives rise to a somewhat enhanced rate of Antarctic Bottom Water formation through enhanced near-boundary convection, which is reflected in slightly cooler and fresher global deep-ocean properties and a reduced Antarctic Circumpolar Current as a result of reduced open-ocean convection. Sensitivity studies reveal that it is not the overall enhanced lead fraction but rather the coastal katabatic winds that lead to this behaviour of the higher-resolution model. Artifacts resulting from the coarse-grid coastline were minimized in a separate model version where fine surface grid cells of fast ice were introduced following the fine-grid land/ice-shelf—sea-ice/ocean boundary of satellite-derived microwave data. This study represents an intermediate step toward resolving the sea-ice component of a global coarse-resolution ocean GCM on a scale of about 30 km.

  12. Role of zooplankton dynamics for Southern Ocean phytoplankton biomass and global biogeochemical cycles

    NASA Astrophysics Data System (ADS)

    Le Quéré, Corinne; Buitenhuis, Erik T.; Moriarty, Róisín; Alvain, Séverine; Aumont, Olivier; Bopp, Laurent; Chollet, Sophie; Enright, Clare; Franklin, Daniel J.; Geider, Richard J.; Harrison, Sandy P.; Hirst, Andrew G.; Larsen, Stuart; Legendre, Louis; Platt, Trevor; Prentice, I. Colin; Rivkin, Richard B.; Sailley, Sévrine; Sathyendranath, Shubha; Stephens, Nick; Vogt, Meike; Vallina, Sergio M.

    2016-07-01

    Global ocean biogeochemistry models currently employed in climate change projections use highly simplified representations of pelagic food webs. These food webs do not necessarily include critical pathways by which ecosystems interact with ocean biogeochemistry and climate. Here we present a global biogeochemical model which incorporates ecosystem dynamics based on the representation of ten plankton functional types (PFTs): six types of phytoplankton, three types of zooplankton, and heterotrophic procaryotes. We improved the representation of zooplankton dynamics in our model through (a) the explicit inclusion of large, slow-growing macrozooplankton (e.g. krill), and (b) the introduction of trophic cascades among the three zooplankton types. We use the model to quantitatively assess the relative roles of iron vs. grazing in determining phytoplankton biomass in the Southern Ocean high-nutrient low-chlorophyll (HNLC) region during summer. When model simulations do not include macrozooplankton grazing explicitly, they systematically overestimate Southern Ocean chlorophyll biomass during the summer, even when there is no iron deposition from dust. When model simulations include a slow-growing macrozooplankton and trophic cascades among three zooplankton types, the high-chlorophyll summer bias in the Southern Ocean HNLC region largely disappears. Our model results suggest that the observed low phytoplankton biomass in the Southern Ocean during summer is primarily explained by the dynamics of the Southern Ocean zooplankton community, despite iron limitation of phytoplankton community growth rates. This result has implications for the representation of global biogeochemical cycles in models as zooplankton faecal pellets sink rapidly and partly control the carbon export to the intermediate and deep ocean.

  13. Global patterns in efficiency of particulate organic carbon export and transfer to the deep ocean

    NASA Astrophysics Data System (ADS)

    Henson, Stephanie A.; Sanders, Richard; Madsen, Esben

    2012-03-01

    The ocean's biological carbon pump is a key component of the global carbon cycle. Only a small fraction of the carbon fixed by primary production is exported to the deep ocean, yet this flux sets to first order the efficiency with which carbon is sequestered out of further contact with the atmosphere on long time scales. Here we examine global patterns in particle export efficiency (PEeff), the proportion of primary production that is exported from the surface ocean, and transfer efficiency (Teff), the fraction of exported organic matter that reaches the deep ocean. Previous studies have found a positive correlation between Teff and deep ocean calcite fluxes recovered from sediment traps, implying that ballasting by calcium carbonate may play an important role in regulating Teff. An alternative explanation is that this correlation is not causative, as regions where the dominant biomineral phase is calcite tend to be subtropical systems, which are hypothesized to produce sinking aggregates highly resistant to degradation. We attempt to distinguish between these alternative hypotheses on the control of Teff by examining the relationship between Teff and biomineral phases exported from the upper ocean, rather than those collected in deep traps. Global scale estimates derived from satellite data show, in keeping with earlier studies, that PEeff is high at high latitudes and low at low latitudes, but that Teff is low at high latitudes and high at low latitudes. However, in contrast to the relationship observed for deep biomineral fluxes in previous studies, we find that Teff is strongly negatively correlated with opal export flux from the upper ocean, but uncorrelated with calcium carbonate export flux. We hypothesize that the underlying factor governing the spatial patterns observed in Teff is ecosystem function, specifically the degree of recycling occurring in the upper ocean, rather than the availability of calcium carbonate for ballasting.

  14. Biogeochemical drivers of the fate of riverine mercury discharged to the global and Arctic oceans

    NASA Astrophysics Data System (ADS)

    Zhang, Yanxu; Jacob, Daniel J.; Dutkiewicz, Stephanie; Amos, Helen M.; Long, Michael S.; Sunderland, Elsie M.

    2015-06-01

    Rivers discharge 28 ± 13 Mmol yr-1 of mercury (Hg) to ocean margins, an amount comparable to atmospheric deposition to the global oceans. Most of the Hg discharged by rivers is sequestered by burial of benthic sediment in estuaries or the coastal zone, but some is evaded to the atmosphere and some is exported to the open ocean. We investigate the fate of riverine Hg by developing a new global 3-D simulation for Hg in the Massachusetts Institute of Technology ocean general circulation model. The model includes plankton dynamics and carbon respiration (DARWIN project model) coupled to inorganic Hg chemistry. Results are consistent with observed spatial patterns and magnitudes of surface ocean Hg concentrations. We use observational constraints on seawater Hg concentrations and evasion to infer that most Hg from rivers is sorbed to refractory organic carbon and preferentially buried. Only 6% of Hg discharged by rivers (1.8 Mmol yr-1) is transported to the open ocean on a global basis. This fraction varies from a low of 2.6% in East Asia due to the barrier imposed by the Korean Peninsula and Japanese archipelago, up to 25% in eastern North America facilitated by the Gulf Stream. In the Arctic Ocean, low tributary particle loads and efficient degradation of particulate organic carbon by deltaic microbial communities favor a more labile riverine Hg pool. Evasion of Hg to the Arctic atmosphere is indirectly enhanced by heat transport during spring freshet that accelerates sea ice melt and ice rafting. Discharges of 0.23 Mmol Hg yr-1 from Arctic rivers can explain the observed summer maximum in the Arctic atmosphere, and this magnitude of releases is consistent with recent observations. Our work indicates that rivers are major contributors to Hg loads in the Arctic Ocean.

  15. Assessment of dissolved Pb concentration and isotopic composition in surface waters of the modern global ocean

    NASA Astrophysics Data System (ADS)

    Pinedo-Gonzalez, P.; West, A. J.; Sanudo-Wilhelmy, S. A.

    2015-12-01

    Lead (Pb) produced by human activities, mainly from leaded gasoline combustion and high-temperature industries, dominates Pb in our present-day oceans. Previous studies have shown that surface ocean Pb concentrations and isotope ratios have varied in time and space, reflecting the changes in the amount of inputs and sources of anthropogenic Pb. However, data on surface ocean Pb is quite limited, especially for some basins like the Indian Ocean. In the present study, Pb concentrations and stable isotopes (208, 207, and 206) have been analyzed in surface water samples (3m depth) collected during the Malaspina Circumnavigation Expedition, 2010. Our results are compared with data from the literature to i) evaluate the changing status of metal contamination in surface waters of the global ocean over the last 30 years, and ii) propose potential sources of modern Pb to the oceans. Our results show that Pb concentrations in surface waters of the North Atlantic Ocean have decreased ~ 40% since 1975, attributable to the phase-out of leaded gasoline in North America. This result is corroborated by stable Pb isotope measurements. Furthermore, the isotopic gradient observed in surface waters of the studied transects in the north tropical and subtropical Atlantic Ocean can be attributed to simple mixing of European and African aerosols and Saharan Holocene loess. Results from an understudied transect in the Southern Indian Ocean give an indication of the source region of Pb delivered to this region. Although comparison with literature data is limited, mixing of Australian ores and African and Australian coals could potentially explain the measured Pb isotope composition. This study provides an opportunity to build on the work of previous oceanographic campaigns, enabling us to assess the impact of anthropogenic Pb inputs to the ocean and the relative importance of various Pb sources, providing new insights into the transport and fate of Pb in the oceans.

  16. The ocean quasi-homogeneous layer model and global cycle of carbon dioxide in system of atmosphere-ocean

    NASA Astrophysics Data System (ADS)

    Glushkov, Alexander; Glushkov, Alexander; Loboda, Nataliya; Khokhlov, Valery; Serbov, Nikoly; Svinarenko, Andrey

    The purpose of this paper is carrying out the detailed model of the CO2 global turnover in system of "atmosphere-ocean" with using the ocean quasi-homogeneous layer model. Practically all carried out models are functioning in the average annual regime and accounting for the carbon distribution in bio-sphere in most general form (Glushkov et al, 2003). We construct a modified model for cycle of the carbon dioxide, which allows to reproduce a season dynamics of carbon turnover in ocean with account of zone ocean structure (up quasi-homogeneous layer, thermocline and deepest layer). It is taken into account dependence of the CO2 transfer through the bounder between atmosphere and ocean upon temperature of water and air, wind velocity, buffer mechanism of the CO2 dissolution. The same program is realized for atmosphere part of whole system. It is obtained a tempo-ral and space distribution for concentration of non-organic carbon in ocean, partial press of dissolute CO2 and value of exchange on the border between atmosphere and ocean. It is estimated a role of the wind intermixing of the up ocean layer. The increasing of this effect leads to increasing the plankton mass and further particles, which are transferred by wind, contribute to more quick immersion of microscopic shells and organic material. It is fulfilled investigation of sen-sibility of the master differential equations system solutions from the model parameters. The master differential equa-tions system, describing a dynamics of the CO2 cycle, is numerically integrated by the four order Runge-Cutt method under given initial values of valuables till output of solution on periodic regime. At first it is indicated on possible real-zation of the chaos scenario in system. On our data, the difference of the average annual values for the non-organic car-bon concentration in the up quasi-homogeneous layer between equator and extreme southern zone is 0.15 mol/m3, be-tween the equator and extreme northern zone is 0

  17. New Community Education Program on Oceans and Global Climate Change: Results from Our Pilot Year

    NASA Astrophysics Data System (ADS)

    Bruno, B. C.; Wiener, C.

    2010-12-01

    Ocean FEST (Families Exploring Science Together) engages elementary school students and their parents and teachers in hands-on science. Through this evening program, we educate participants about ocean and earth science issues that are relevant to their local communities. In the process, we hope to inspire more underrepresented students, including Native Hawaiians, Pacific Islanders and girls, to pursue careers in the ocean and earth sciences. Hawaii and the Pacific Islands will be disproportionately affected by the impacts of global climate change, including rising sea levels, coastal erosion, coral reef degradation and ocean acidification. It is therefore critically important to train ocean and earth scientists within these communities. This two-hour program explores ocean properties and timely environmental topics through six hands-on science activities. Activities are designed so students can see how globally important issues (e.g., climate change and ocean acidification) have local effects (e.g., sea level rise, coastal erosion, coral bleaching) which are particularly relevant to island communities. The Ocean FEST program ends with a career component, drawing parallel between the program activities and the activities done by "real scientists" in their jobs. The take-home message is that we are all scientists, we do science every day, and we can choose to do this as a career. Ocean FEST just completed our pilot year. During the 2009-2010 academic year, we conducted 20 events, including 16 formal events held at elementary schools and 4 informal outreach events. Evaluation data were collected at all formal events. Formative feedback from adult participants (parents, teachers, administrators and volunteers) was solicited through written questionnaires. Students were invited to respond to a survey of five questions both before and after the program to see if there were any changes in content knowledge and career attitudes. In our presentation, we will present our

  18. Ocean biogeochemical response to phytoplankton-light feedback in a global model

    NASA Astrophysics Data System (ADS)

    Manizza, Manfredi; Le QuéRé, Corinne; Watson, Andrew J.; Buitenhuis, Erik T.

    2008-10-01

    Oceanic phytoplankton, absorbing solar radiation, can influence the bio-optical properties of seawater and hence upper ocean physics. We include this process in a global ocean general circulation model (OGCM) coupled to a dynamic green ocean model (DGOM) based on multiple plankton functional types (PFT). We not only study the impact of this process on ocean physics but we also explore the biogeochemical response due to this biophysical feedback. The phytoplankton-light feedback (PLF) impacts the dynamics of the upper tropical and subtropical oceans. The change in circulation enhances both the vertical supply in the tropics and the lateral supply of nutrients from the tropics to the subtropics boosting the subtropical productivity by up to 60 gC m-2 a-1. Physical changes, due to the PLF, impact on light and nutrient availability causing shifts in the ocean ecosystems. In the extratropics, increased stratification favors calcifiers (by up to ˜8%) at the expense of mixed phytoplankton. In the Southern Ocean, silicifiers increase their biomass (by up to ˜10%) because of the combined alleviation of iron and light limitation. The PLF has a small effect globally on air-sea fluxes of carbon dioxide (CO2, 72 TmolC a-1 outgassing) and oxygen (O2, 46 TmolO2 a-1 ingassing) because changes in biogeochemical processes (primary production, biogenic calcification, and export production) highly vary regionally and can also oppose each other. From our study it emerges that the main impact of the PLF is an amplification of the seasonal cycle of physical and biogeochemical properties of the high-latitude oceans mostly driven by the amplification of the SST seasonal cycle.

  19. Interactive Ocean Observatories are Essential for Global Assessment of Plate-tectonically Modulated Microbial Input to the Deep Ocean

    NASA Astrophysics Data System (ADS)

    Delaney, J.; Team, K.

    2004-12-01

    A major new planetary-scale research thrust can only be addressed with interactive, next-generation ocean-observatory capabilities. These new research opportunities arise from the possibility that input into the ocean of chemosynthetically derived microbial biomass from below the seafloor rivals the biomass from primary photosynthetic productivity near the top of the ocean. All three types of plate boundaries and many plate interiors vent microbe-bearing fluids into the deep ocean continuously AND episodically. Unpredicted episodes increase nutrient output and venting volume by as much as a factor of 100 for weeks to months at a time (Lilley et al.,2003, Nature). Because of the highly non-linear nature of these fluxes, quantification of such processes represents essential, but unconstrained, variables in equations for carbon budgets and bio-flux in the deep ocean. Triggering events and their induced fluxes must be detected, located, responded to, and quantified before their relative importance to the global-ocean system can be evaluated. Addressing these issues requires an essential new capability in the ocean sciences. High-power and high-bandwidth cabled systems will enable remote and long-term experimentation with processes via thousands of stationary and/or mobile sensor platforms on, below, and above the seafloor. The Ocean Research Interactive Observatory Networks (ORION) program is currently working with NEPTUNE Canada to produce a plate-tectonic-scale, regional cabled ocean observatory (RCO), an ideal platform for adaptive surveillance and quantitative response to fluid-flux generating events at the margins and interior of the Juan de Fuca (JdF) Plate. The W. M. Keck Foundation is supporting a pre-NEPTUNE exploration of the linked processes involved in the deformation-fluid/microbial flux concept. Thirteen seismometers (3 broadband, 10 short-period) and 45 fluid-movement/chemical sensors are co-deployed on three different, but adjacent, plate boundaries at

  20. Prospects for improving the representation of coastal and shelf seas in global ocean models

    NASA Astrophysics Data System (ADS)

    Holt, Jason; New, Adrian; Liu, Hedong; Coward, Andrew; Ashworth, Mike; Pickles, Stephen; Harle, James; Siddorn, John

    2013-04-01

    The ability to accurately represent coastal and shelf seas in global scale ocean models represents one of the on-going challenges of ocean modelling, particularly when the global model is to be used in biogeochemical, climate and Earth System simulations. The motivation for this is, however, wide ranging and includes both upscaling and downscaling issues. The dynamic motivation includes dense water formation on high latitude shelves and cascading into the deeper ocean, lateral frictional/mixing effects, pinch points and exchange regions, whereas the biogeochemical motivation include carbon and nutrient cycling, shelf-ocean exchanges and land-sea coupling. Moreover, society interacts with the ocean at a local/regional scale for example through the exploitation of Living Marine Resources and the drive to achieve and maintain Good Environmental Status. Hence, global assessments of vulnerability to climate change and other large scale drivers require information at the scale of this interaction. Here, we review the physical processes prevalent in shelf seas globally and their scales, and provide a baseline assessment of three global model configurations (NEMO at resolutions of 1, 1/4 and 1/12 deg.) and a regional model (NEMO AMM7;~7km resolution) focusing on the NW European continental shelf. Then we discuss the options for improving on this position based on current and prospective modelling approaches. We contrast structured and unstructured (finite element and finite volume) approaches, highlighting some novel ways forward for both, including generalised grid methods and global nesting approaches. We conclude that a single solution is not available currently or on intermediate timescales that can accommodate both upscaling and downscaling for both the dynamics and biogeochemistry, particularly in an Earth Systems context; as is often the case the choice of approach remains context dependent. Instead, we match the various options with the original motivations and

  1. Global effects of changes in wind forcing of Southern Indian Ocean

    SciTech Connect

    Altman, D.B. ); Semtner, A.J. ); Chervin, R.M. )

    1990-01-09

    An identical twin numerical experiment has been performed using the global ocean circulation model of Semtner and Chervin. The wind forcing within a band of 120[degree] East [+-] 45[degrees] and 50[degrees] South [+-] 5[degrees] was varied smoothly in space and time to be approximately 4% greater for the twin run than the original. The twin experiment was run for 60 model days. Within nine days small changes of mass transport of the N. Guiana current were observed. Within 24 days changes appeared in mass transport of Pacific Equatorial Rossby waves, and after 60 days mass transport changes were seen in all ocean basins. Within three days small differences in 160 m (mid-thermocline) temperature appeared in the Atlantic basin. Within thirty days, similar changes were evident globally. Similar results were found for mid-thermocline horizontal velocity. These results imply a predictability limit to the accuracy of ocean circulation models due to rapid communication of wave energy between ocean basins. Changes to Pacific Equatorial Rossby wave transport imply possible effects on El Nino by Southern Indian Ocean winds via oceanic coupling.

  2. Tropical Ocean and Global Atmosphere (TOGA) heat exchange project: A summary report

    NASA Technical Reports Server (NTRS)

    Liu, W. T.; Niiler, P. P.

    1985-01-01

    A pilot data center to compute ocean atmosphere heat exchange over the tropical ocean is prposed at the Jet Propulsion Laboratory (JPL) in response to the scientific needs of the Tropical Ocean and Global Atmosphere (TOGA) Program. Optimal methods will be used to estimate sea surface temperature (SET), surface wind speed, and humidity from spaceborne observations. A monthly summary of these parameters will be used to compute ocean atmosphere latent heat exchanges. Monthly fields of surface heat flux over tropical oceans will be constructed using estimations of latent heat exchanges and short wave radiation from satellite data. Verification of all satellite data sets with in situ measurements at a few locations will be provided. The data center will be an experimental active archive where the quality and quantity of data required for TOGA flux computation are managed. The center is essential to facilitate the construction of composite data sets from global measurements taken from different sensors on various satellites. It will provide efficient utilization and easy access to the large volume of satellite data available for studies of ocean atmosphere energy exchanges.

  3. Evaluation of MODIS/CERES downwelling shortwave and longwave radiation over global tropical oceans

    NASA Astrophysics Data System (ADS)

    Venugopal, T.; Rahaman, H.; Ravichandran, M.; Ramakrishna, S. S. V. S.

    2016-05-01

    In the present work, we have evaluated the satellite estimated daily downwelling shortwave (QI) and Longwave (QA) radiation from Moderate Resolution Imaging Spectrometer (MODIS) /Clouds and the Earth's Radiant Energy System (CM) with moored buoy observations of Global Tropical Moored Buoy Array (GTMBA) during 2001-2009. The global observed mean of QI and QA in GTMBA (CM) are 228 (233) W/m2 and 410 (405) W/m2 respectively. The mean QI shows a positive bias (~3- 7 W/m2) whereas QA underestimates with a mean negative bias of ~3-6 W/m2 in the tropical Pacific, Atlantic and Indian Ocean. CM underestimates the buoy observed variability in both QI and QA in all the tropical oceans. The correlation coefficient (CC) values in QI (Qa) are 0.79(0.88) 0.79(0.84) and 0.81(0.94) over the Pacific, Atlantic and Indian ocean respectively. The Root Mean Square Error (RMSE) values in QI ranged between 35-43 W/m2 with lowest values in the Atlantic Ocean and highest in the Indian Ocean. The RMSE values in QA are less as compared to QI and it is ~9 W/m2 in all the tropical ocean. The spatial distributions of QI and QA shows seasonality with lower and higher values coinciding with the Inter Tropical Convergence Zone(ITCZ) locations in the QI and QA.

  4. Industrial-era global ocean heat uptake doubles in recent decades

    NASA Astrophysics Data System (ADS)

    Gleckler, Peter J.; Durack, Paul J.; Stouffer, Ronald J.; Johnson, Gregory C.; Forest, Chris E.

    2016-04-01

    Formal detection and attribution studies have used observations and climate models to identify an anthropogenic warming signature in the upper (0-700 m) ocean. Recently, as a result of the so-called surface warming hiatus, there has been considerable interest in global ocean heat content (OHC) changes in the deeper ocean, including natural and anthropogenically forced changes identified in observational, modelling and data re-analysis studies. Here, we examine OHC changes in the context of the Earth’s global energy budget since early in the industrial era (circa 1865-2015) for a range of depths. We rely on OHC change estimates from a diverse collection of measurement systems including data from the nineteenth-century Challenger expedition, a multi-decadal record of ship-based in situ mostly upper-ocean measurements, the more recent near-global Argo floats profiling to intermediate (2,000 m) depths, and full-depth repeated transoceanic sections. We show that the multi-model mean constructed from the current generation of historically forced climate models is consistent with the OHC changes from this diverse collection of observational systems. Our model-based analysis suggests that nearly half of the industrial-era increases in global OHC have occurred in recent decades, with over a third of the accumulated heat occurring below 700 m and steadily rising.

  5. Global survey of carbon dioxide in the ocean. Progress report, January 1, 1993--December 31, 1993

    SciTech Connect

    Sabine, C.; Key, R.M.; Sarmiento, J.L.

    1993-09-01

    This proposal was submitted in response to the DOE call for proposals to participate in obtaining carbon system measurements as part of the World Ocean Circulation Experiment/Hydrographic Program (WOCE/HP). The authors` interest in participating in this global survey stemmed from two major research directions in which our their has been actively involved. The first is the DOE supported ocean carbon cycle model development program. The models developed as part of this program clearly demonstrate the importance of ocean carbon measurements in constraining the oceanic sink of anthropogenic carbon dioxide. The creation of a CO{sub 2} measurement program at Princeton allowed the unique ability for a close interaction between the modellers and the people actually making the measurements. This interaction strengthens both programs.

  6. Recent Short Term Global Aerosol Trends over Land and Ocean Dominated by Biomass Burning

    NASA Technical Reports Server (NTRS)

    Remer, Lorraine A.; Koren, Ilan; Kleidman, RIchard G.; Levy, Robert C.; Martins, J. Vanderlei; Kim, Kyu-Myong; Tanre, Didier; Mattoo, Shana; Yu, Hongbin

    2007-01-01

    NASA's MODIS instrument on board the Terra satellite is one of the premier tools to assess aerosol over land and ocean because of its high quality calibration and consistency. We analyze Terra-MODIS's seven year record of aerosol optical depth (AOD) observations to determine whether global aerosol has increased or decreased during this period. This record shows that AOD has decreased over land and increased over ocean. Only the ocean trend is statistically significant and corresponds to an increase in AOD of 0.009, or a 15% increase from background conditions. The strongest increasing trends occur over regions and seasons noted for strong biomass burning. This suggests that biomass burning aerosol dominates the increasing trend over oceans and mitigates the otherwise mostly negative trend over the continents.

  7. M2, S2, K1 models of the global ocean tide

    NASA Technical Reports Server (NTRS)

    Parke, M. E.; Hendershott, M. C.

    1979-01-01

    Ocean tidal signals appear in many geophysical measurements. Geophysicists need realistic tidal models to aid in interpretation of their data. Because of the closeness to resonance of dissipationless ocean tides, it is difficult for numerical models to correctly represent the actual open ocean tide. As an approximate solution to this problem, test functions derived by solving Laplace's Tidal Equations with ocean loading and self gravitation are used as a basis for least squares dynamic interpolation of coastal and island tidal data for the constituents M2, S2, and Kl. The resulting representations of the global tide are stable over at least a ?5% variation in the mean depth of the model basin, and they conserve mass. Maps of the geocentric tide, the induced free space potential, the induced vertical component of the solid earth tide, and the induced vertical component of the gravitational field for each contituent are presented.

  8. Oceanic carbon dioxide uptake in a model of century-scale global warming

    SciTech Connect

    Sarmiento, J.L.; Le Quere, C.

    1996-11-22

    In a model of ocean-atmosphere interaction that excluded biological processes, the oceanic uptake of atmospheric carbon dioxide (CO{sub 2}) was substantially reduced in scenarios involving global warming relative to control scenarios. The primary reason for the reduced uptake was the weakening or collapse of the ocean thermohaline circulation. Such a large reduction in this ocean uptake would have a major impact o the future growth rate of atmospheric CO{sub 2}. Model simulations that include a simple representation of biological processes show a potentially large offsetting effect resulting from the downward flux of biogenic carbon. However, the magnitude of the offset is difficult to quantify with present knowledge. 19 refs., 3 figs., 2 tabs.

  9. The CONCEPTS Global Ice-Ocean Prediction System: Establishing an Environmental Prediction Capability in Canada

    NASA Astrophysics Data System (ADS)

    Pellerin, Pierre; Smith, Gregory; Testut, Charles-Emmanuel; Surcel Colan, Dorina; Roy, Francois; Reszka, Mateusz; Dupont, Frederic; Lemieux, Jean-Francois; Beaudoin, Christiane; He, Zhongjie; Belanger, Jean-Marc; Deacu, Daniel; Lu, Yimin; Buehner, Mark; Davidson, Fraser; Ritchie, Harold; Lu, Youyu; Drevillon, Marie; Tranchant, Benoit; Garric, Gilles

    2015-04-01

    Here we describe a new system implemented recently at the Canadian Meteorological Centre (CMC) entitled the Global Ice Ocean Prediction System (GIOPS). GIOPS provides ice and ocean analyses and 10 day forecasts daily at 00GMT on a global 1/4° resolution grid. GIOPS includes a full multivariate ocean data assimilation system that combines satellite observations of sea level anomaly and sea surface temperature (SST) together with in situ observations of temperature and salinity. In situ observations are obtained from a variety of sources including: the Argo network of autonomous profiling floats, moorings, ships of opportunity, marine mammals and research cruises. Ocean analyses are blended with sea ice analyses produced by the Global Ice Analysis System.. GIOPS has been developed as part of the Canadian Operational Network of Coupled Environmental PredicTion Systems (CONCEPTS) tri-departmental initiative between Environment Canada, Fisheries and Oceans Canada and National Defense. The development of GIOPS was made through a partnership with Mercator-Océan, a French operational oceanography group. Mercator-Océan provided the ocean data assimilation code and assistance with the system implementation. GIOPS has undergone a rigorous evaluation of the analysis, trial and forecast fields demonstrating its capacity to provide high-quality products in a robust and reliable framework. In particular, SST and ice concentration forecasts demonstrate a clear benefit with respect to persistence. These results support the use of GIOPS products within other CMC operational systems, and more generally, as part of a Government of Canada marine core service. Impact of a two-way coupling between the GEM atmospheric model and NEMO-CICE ocean-ice model will also be presented.

  10. Twenty Years of Progress on Global Ocean Tides: The Impact of Satellite Altimetry

    NASA Technical Reports Server (NTRS)

    Egbert, Gary; Ray, Richard

    2012-01-01

    At the dawn of the era of high-precision altimetry, before the launch of TOPEX/Poseidon, ocean tides were properly viewed as a source of noise--tidal variations in ocean height would represent a very substantial fraction of what the altimeter measures, and would have to be accurately predicted and subtracted if altimetry were to achieve its potential for ocean and climate studies. But to the extent that the altimetry could be severely contaminated by tides, it also represented an unprecedented global-scale tidal data set. These new data, together with research stimulated by the need for accurate tidal corrections, led to a renaissance in tidal studies in the oceanographic community. In this paper we review contributions of altimetry to tidal science over the past 20 years, emphasizing recent progress. Mapping of tides has now been extended from the early focus on major constituents in the open ocean to include minor constituents, (e.g., long-period tides; non-linear tides in shelf waters, and in the open ocean), and into shallow and coastal waters. Global and spatially local estimates of tidal energy balance have been refined, and the role of internal tide conversion in dissipating barotropic tidal energy is now well established through modeling, altimetry, and in situ observations. However, energy budgets for internal tides, and the role of tidal dissipation in vertical ocean mixing remain controversial topics. Altimetry may contribute to resolving some of these important questions through improved mapping of low-mode internal tides. This area has advanced significantly in recent years, with several global maps now available, and progress on constraining temporally incoherent components. For the future, new applications of altimetry (e.g., in the coastal ocean, where barotropic tidal models remain inadequate), and new mission concepts (studies of the submesoscale with SWOT, which will require correction for internal tides) may bring us full circle, again pushing

  11. Preface to special issue (Impacts of surface ocean acidification in polar seas and globally: A field-based approach)

    NASA Astrophysics Data System (ADS)

    Tyrrell, Toby; Tarling, Geraint A.; Leakey, Raymond J. G.; Cripps, Gemma; Thorpe, Sally; Richier, Sophie; Mark Moore, C.

    2016-05-01

    Both ocean acidification and global warming are consequences of the rise in atmospheric CO2. Ocean acidification is not itself a consequence of global warming, but rather of the invasion of atmospheric CO2 into the ocean. Time-series of carbonate chemistry measurements in different locations around the world all document the continuous and ongoing increase in the amount of CO2 in the ocean, and the consequential accompanying decrease in surface ocean seawater pH at all sites over the last years (Bates et al., 2014).

  12. Twelve previously unknown phage genera are ubiquitous in global oceans

    SciTech Connect

    Holmfeldt, Karin; Solonenko, Natalie; Shah, Manesh B; Corrier, Kristen L; Riemann, Lasse; Verberkmoes, Nathan C; Sullivan, Matthew B

    2013-01-01

    Viruses are fundamental to ecosystems ranging from oceans to humans, yet our ability to study them is bottlenecked by the lack of ecologically relevant isolates, resulting in unknowns dominating culture-independent surveys. Here we present genomes from 31 phages infecting multiple strains of the aquatic bacterium Cellulophaga baltica (Bacteroidetes) to provide data for an underrepresented and environmentally abundant bacterial lineage. Comparative genomics delineated 12 phage groups that (i) each represent a new genus, and (ii) represent one novel and four wellknown viral families. This diversity contrasts the few well-studied marine phage systems, but parallels the diversity of phages infecting human-associated bacteria. Although all 12 Cellulophaga phages represent new genera, the podoviruses and icosahedral, nontailed ssDNA phages were exceptional, with genomes up to twice as large as those previously observed for each phage type. Structural novelty was also substantial, requiring experimental phage proteomics to identify 83% of the structural proteins. The presence of uncommon nucleotide metabolism genes in four genera likely underscores the importance of scavenging nutrient-rich molecules as previously seen for phages in marine environments. Metagenomic recruitment analyses suggest that these particular Cellulophaga phages are rare and may represent a first glimpse into the phage side of the rare biosphere. However, these analyses also revealed that these phage genera are widespread, occurring in 94% of 137 investigated metagenomes. Together, this diverse and novel collection of phages identifies a small but ubiquitous fraction of unknown marine viral diversity and provides numerous environmentally relevant phage host systems for experimental hypothesis testing.

  13. Twelve previously unknown phage genera are ubiquitous in global oceans.

    PubMed

    Holmfeldt, Karin; Solonenko, Natalie; Shah, Manesh; Corrier, Kristen; Riemann, Lasse; Verberkmoes, Nathan C; Sullivan, Matthew B

    2013-07-30

    Viruses are fundamental to ecosystems ranging from oceans to humans, yet our ability to study them is bottlenecked by the lack of ecologically relevant isolates, resulting in "unknowns" dominating culture-independent surveys. Here we present genomes from 31 phages infecting multiple strains of the aquatic bacterium Cellulophaga baltica (Bacteroidetes) to provide data for an underrepresented and environmentally abundant bacterial lineage. Comparative genomics delineated 12 phage groups that (i) each represent a new genus, and (ii) represent one novel and four well-known viral families. This diversity contrasts the few well-studied marine phage systems, but parallels the diversity of phages infecting human-associated bacteria. Although all 12 Cellulophaga phages represent new genera, the podoviruses and icosahedral, nontailed ssDNA phages were exceptional, with genomes up to twice as large as those previously observed for each phage type. Structural novelty was also substantial, requiring experimental phage proteomics to identify 83% of the structural proteins. The presence of uncommon nucleotide metabolism genes in four genera likely underscores the importance of scavenging nutrient-rich molecules as previously seen for phages in marine environments. Metagenomic recruitment analyses suggest that these particular Cellulophaga phages are rare and may represent a first glimpse into the phage side of the rare biosphere. However, these analyses also revealed that these phage genera are widespread, occurring in 94% of 137 investigated metagenomes. Together, this diverse and novel collection of phages identifies a small but ubiquitous fraction of unknown marine viral diversity and provides numerous environmentally relevant phage-host systems for experimental hypothesis testing. PMID:23858439

  14. Seven-Year SSM/I-Derived Global Ocean Surface Turbulent Fluxes

    NASA Technical Reports Server (NTRS)

    Chou, Shu-Hsien; Shie, Chung-Lin; Atlas, Robert M.; Ardizzone, Joe

    2000-01-01

    A 7.5-year (July 1987-December 1994) dataset of daily surface specific humidity and turbulent fluxes (momentum, latent heat, and sensible heat) over global oceans has been retrieved from the Special Sensor Microwave/Imager (SSM/I) data and other data. It has a spatial resolution of 2.0 deg.x 2.5 deg. latitude-longitude. The retrieved surface specific humidity is generally accurate over global oceans as validated against the collocated radiosonde observations. The retrieved daily wind stresses and latent heat fluxes show useful accuracy as verified by those measured by the RV Moana Wave and IMET buoy in the western equatorial Pacific. The derived turbulent fluxes and input variables are also found to agree generally with the global distributions of annual-and seasonal-means of those based on 4-year (1990-93) comprehensive ocean-atmosphere data set (COADS) with adjustment in wind speeds and other climatological studies. The COADS has collected the most complete surface marine observations, mainly from merchant ships. However, ship measurements generally have poor accuracy, and variable spatial coverages. Significant differences between the retrieved and COADS-based are found in some areas of the tropical and southern extratropical oceans, reflecting the paucity of ship observations outside the northern extratropical oceans. Averaged over the global oceans, the retrieved wind stress is smaller but the latent heat flux is larger than those based on COADS. The former is suggested to be mainly due to overestimation of the adjusted ship-estimated wind speeds (depending on sea states), while the latter is suggested to be mainly due to overestimation of ship-measured dew point temperatures. The study suggests that the SSM/I-derived turbulent fluxes can be used for climate studies and coupled model validations.

  15. Toward a global ocean data assimilation system based on ensemble optimum interpolation: altimetry data assimilation experiment

    NASA Astrophysics Data System (ADS)

    Fu, Weiwei; Zhu, Jiang; Yan, Changxiang; Liu, Hailong

    2009-08-01

    A global ocean data assimilation system based on the ensemble optimum interpolation (EnOI) has been under development as the Chinese contribution to the Global Ocean Data Assimilation Experiment. The system uses a global ocean general circulation model, which is eddy permitting, developed by the Institute of Atmospheric Physics of the Chinese Academy of Sciences. In this paper, the implementation of the system is described in detail. We describe the sampling strategy to generate the stationary ensembles for EnOI. In addition, technical methods are introduced to deal with the requirement of massive memory space to hold the stationary ensembles of the global ocean. The system can assimilate observations such as satellite altimetry, sea surface temperature (SST), in situ temperature and salinity from Argo, XBT, Tropical Atmosphere Ocean (TAO), and other sources in a straightforward way. As a first step, an assimilation experiment from 1997 to 2001 is carried out by assimilating the sea level anomaly (SLA) data from TOPEX/Poseidon. We evaluate the performance of the system by comparing the results with various types of observations. We find that SLA assimilation shows very positive impact on the modeled fields. The SST and sea surface height fields are clearly improved in terms of both the standard deviation and the root mean square difference. In addition, the assimilation produces some improvements in regions where mesoscale processes cannot be resolved with the horizontal resolution of this model. Comparisons with TAO profiles in the Pacific show that the temperature and salinity fields have been improved to varying degrees in the upper ocean. The biases with respect to the independent TAO profiles are reduced with a maximum magnitude of about 0.25°C and 0.1 psu for the time-averaged temperature and salinity. The improvements on temperature and salinity also lead to positive impact on the subsurface currents. The equatorial under current is enhanced in the Pacific

  16. A 1/16° eddying simulation of the global NEMO sea-ice-ocean system

    NASA Astrophysics Data System (ADS)

    Iovino, Doroteaciro; Masina, Simona; Storto, Andrea; Cipollone, Andrea; Stepanov, Vladimir N.

    2016-08-01

    Analysis of a global eddy-resolving simulation using the NEMO general circulation model is presented. The model has 1/16° horizontal spacing at the Equator, employs two displaced poles in the Northern Hemisphere, and uses 98 vertical levels. The simulation was spun up from rest and integrated for 11 model years, using ERA-Interim reanalysis as surface forcing. Primary intent of this hindcast is to test how the model represents upper ocean characteristics and sea ice properties. Analysis of the zonal averaged temperature and salinity, and the mixed layer depth indicate that the model average state is in good agreement with observed fields and that the model successfully represents the variability in the upper ocean and at intermediate depths. Comparisons against observational estimates of mass transports through key straits indicate that most aspects of the model circulation are realistic. As expected, the simulation exhibits turbulent behaviour and the spatial distribution of the sea surface height (SSH) variability from the model is close to the observed pattern. The distribution and volume of the sea ice are, to a large extent, comparable to observed values. Compared with a corresponding eddy-permitting configuration, the performance of the model is significantly improved: reduced temperature and salinity biases, in particular at intermediate depths, improved mass and heat transports, better representation of fluxes through narrow and shallow straits, and increased global-mean eddy kinetic energy (by ˜ 40 %). However, relatively minor weaknesses still exist such as a lower than observed magnitude of the SSH variability. We conclude that the model output is suitable for broader analysis to better understand upper ocean dynamics and ocean variability at global scales. This simulation represents a major step forward in the global ocean modelling at the Euro-Mediterranean Centre on Climate Change and constitutes the groundwork for future applications to short

  17. Interannual and Spatial Variability of Global Ocean Heat/Freshwater Content Identified from GTSPP

    NASA Astrophysics Data System (ADS)

    Chu, P. C.; Sun, C.

    2013-12-01

    Global Temperature and Salinity Profile Program (GTSPP) is a cooperative international project since 1990. The GTSPP handles all temperature and salinity profile data including XBT, CTDs, thermistor chain data, and Argo observations. Near-real time gridded (T, S) dataset was established from GTSPP since 1990 with horizontal resolution of (1o×1o) and temporal increment of 1 month using the recently developed optimal spectral decomposition (OSD) method. With this new monthly varying gridded dataset, the upper ocean (surface to 300 m depth) heat content OHC300 and freshwater content FWC300 were calculated at each horizontal grid point. The empirical orthogonal function (EOF) analysis was conducted on the temporally varying global 2D OHC300 anomaly relative to its seasonal variation. A new phenomenon, global ocean tripole, was discovered. The EOF-1 mode (44.2% variance) represents the classical El Nino/La Nina phenomenon. The EOF-2 mode (14.6%) represents the Indian Ocean Dipole mode and the El Nino Modoki. Its features and connection to climate variability is also discussed. The empirical orthogonal function (EOF) analysis was conducted on the temporally varying global 2D FWC300 anomaly relative to its seasonal variation. The EOF-1 mode (73.7% variance) represents near global-scale variability with the largest anomaly appearing in the Indian Ocean near southeast of Africa. The first principal component (PC1) shows decadal variability. The temporal-spatial variability represented by the EOF-1 mode shows rapid increasing of global FWC300 from 1999 to 2005 and sustaining the high values after 2005. Interpretations of the observational results to recent global warming will also be presented.

  18. Contrasting correlation patterns between environmental factors and chlorophyll levels in the global ocean

    NASA Astrophysics Data System (ADS)

    Feng, Jianfeng; Durant, Joël. Marcel; Stige, Leif Chr.; Hessen, Dag Olav; Hjermann, Dag Øystein; Zhu, Lin; Llope, Marcos; Stenseth, Nils Chr.

    2015-12-01

    In this study we analyze large-scale satellite-derived data using generalized additive models to characterize the global correlation patterns between environmental forcing and marine phytoplankton biomass. We found systematic differences in the relationships between key environmental drivers (temperature, light, and wind) and ocean chlorophyll in the subtropical/tropical and temperate oceans. For the subtropical/tropical and equatorial oceans, the chlorophyll generally declined with increasing temperature and light, while in temperate oceans, chlorophyll was best explained by bell-shaped or positive functions of temperature and light. The relationship between chlorophyll and wind speed is generally positive in low-latitude oceans and bell shaped in temperate oceans. Our analyses also demonstrated strong and geographically consistent positive autoregressive effects of chlorophyll from 1 month to the next and negative autoregressive effects for measurements 2 months apart. These findings imply possibly different regional phytoplankton responses to environmental forcing, suggesting that future environmental change could affect the tropical and temperate upper ocean chlorophyll levels differently.

  19. Adaptation of a globally important coccolithophore to ocean warming and acidification

    NASA Astrophysics Data System (ADS)

    Schlüter, Lothar; Lohbeck, Kai T.; Gutowska, Magdalena A.; Gröger, Joachim P.; Riebesell, Ulf; Reusch, Thorsten B. H.

    2014-11-01

    Although ocean warming and acidification are recognized as two major anthropogenic perturbations of today's oceans we know very little about how marine phytoplankton may respond via evolutionary change. We tested for adaptation to ocean warming in combination with ocean acidification in the globally important phytoplankton species Emiliania huxleyi. Temperature adaptation occurred independently of ocean acidification levels. Growth rates were up to 16% higher in populations adapted for one year to warming when assayed at their upper thermal tolerance limit. Particulate inorganic (PIC) and organic (POC) carbon production was restored to values under present-day ocean conditions, owing to adaptive evolution, and were 101% and 55% higher under combined warming and acidification, respectively, than in non-adapted controls. Cells also evolved to a smaller size while they recovered their initial PIC:POC ratio even under elevated CO2. The observed changes in coccolithophore growth, calcite and biomass production, cell size and elemental composition demonstrate the importance of evolutionary processes for phytoplankton performance in a future ocean.

  20. Synchrony of trend shifts in Sahel summer rainfall and global oceanic evaporation, 1950-2012

    NASA Astrophysics Data System (ADS)

    Diawara, A.; Tachibana, Y.; Oshima, K.; Nishikawa, H.; Ando, Y.

    2015-11-01

    Between 1950 and 2012, summer (rainy season) rainfall in the Sahel changed from a multi-decadal decreasing trend to an increasing trend (positive trend shift) in the mid-1980s. We found that this trend shift was synchronous with similar trend shifts in global oceanic evaporation and in land precipitation in all continents except the Americas. The trend shift in oceanic evaporation occurred mainly in the Southern Hemisphere (SH) and the subtropical oceans of the Northern Hemisphere (NH). Because increased oceanic evaporation strengthens the atmospheric moisture transport toward land areas, the synchrony of oceanic evaporation and land precipitation is reasonable. Surface scalar winds over the SH oceans also displayed a positive trend shift. Sea surface temperature (SST) displayed a trend shift in the mid-1980s that was negative (increasing, then decreasing) in the SH and positive in the NH. Although SST had opposite trend shifts in both hemispheres, the trend shift in evaporation was positive in both hemispheres. We infer that because strong winds promote evaporative cooling, the trend shift in SH winds strengthened the trend shifts of both SST and evaporation in the SH. Because high SST promotes evaporation, the trend shift in NH SST strengthened the NH trend shift in evaporation. Thus differing oceanic roles in the SH and NH generated the positive trend shift in evaporation; however, the details of moisture transport toward the Sahel are still unclear.

  1. Synthesis and Assimilation Systems - Essential Adjuncts to the Global Ocean Observing System

    NASA Technical Reports Server (NTRS)

    Rienecker, Michele M.; Balmaseda, Magdalena; Awaji, Toshiyuki; Barnier, Bernard; Behringer, David; Bell, Mike; Bourassa, Mark; Brasseur, Pierre; Breivik, Lars-Anders; Carton, James; Cummings, James; Dombrowsky, Eric; Fairall, Chris; Ferry, Nicolas; Forget, Gael; Gregg, Watson; Griffies, Stephen M.; Haines, Keith; Harrison, D. Edward; Heimbach, Patrick; Kamachi, Masafumi; Kent, Elizabeth; Lee, Tony; Le Traon, Pierre-Yves

    2009-01-01

    Ocean assimilation systems synthesize diverse in situ and satellite data streams into four-dimensional state estimates by combining the various observations with the model. Assimilation is particularly important for the ocean where subsurface observations, even today, are sparse and intermittent compared with the scales needed to represent ocean variability and where satellites only sense the surface. Developments in assimilation and in the observing system have advanced our understanding and prediction of ocean variations at mesoscale and climate scales. Use of these systems for assessing the observing system helps identify the strengths of each observation type. Results indicate that the ocean remains under-sampled and that further improvements in the observing system are needed. Prospects for future advances lie in improved models and better estimates of error statistics for both models and observations. Future developments will be increasingly towards consistent analyses across components of the Earth system. However, even today ocean synthesis and assimilation systems are providing products that are useful for many applications and should be considered an integral part of the global ocean observing and information system.

  2. Contamination, misuse and abuse of the global oceans leading to ecosystem damage and destruction, health consequences and international conflict

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Unregulated uses of the oceans may threaten the global ecological balance, alter plant and animal life and significantly impact the global climatic systems. Recent plans to locate large scale structures on the oceans and to exploit the mineral riches of the seas pose even greater risk to the ecological system. Finally, increasing use of the oceans for large scale transport greatly enhances the probability of collision, polluting spills and international conflict.

  3. Global assessment of oceanic lead pollution using sperm whales (Physeter macrocephalus) as an indicator species.

    PubMed

    Savery, Laura C; Wise, Sandra S; Falank, Carolyne; Wise, James; Gianios, Christy; Douglas Thompson, W; Perkins, Christopher; Zheng, Tongzhang; Zhu, Cairong; Wise, John Pierce

    2014-02-15

    Lead (Pb) is an oceanic pollutant of global concern. Anthropogenic activities are increasing oceanic levels, but to an unknown extent. The sperm whale (Physeter macrocephalus) has a global distribution and high trophic level. The aim of this study was to establish a global baseline of oceanic Pb concentrations using free-ranging sperm whales as an indicator species. Skin biopsies (n=337) were collected during the voyage of the Odyssey (2000-2005) from 17 regions considering gender and age. Pb was detectable in 315 samples with a global mean of 1.6 ug/gww ranging from 0.1 to 129.6 ug/gww. Papua New Guinea, Bahamas and Australia had the highest regional mean with 6.1, 3.4, and 3.1 ug/gww, respectively. Pb concentrations were not significantly different between sex and age in males. This is the first global toxicological dataset for Pb in a marine mammal and confirms Pb is widely distributed with hotspots in some regions. PMID:24361115

  4. Global assessment of ocean carbon export by combining satellite observations and food-web models

    NASA Astrophysics Data System (ADS)

    Siegel, D. A.; Buesseler, K. O.; Doney, S. C.; Sailley, S. F.; Behrenfeld, M. J.; Boyd, P. W.

    2014-03-01

    The export of organic carbon from the surface ocean by sinking particles is an important, yet highly uncertain, component of the global carbon cycle. Here we introduce a mechanistic assessment of the global ocean carbon export using satellite observations, including determinations of net primary production and the slope of the particle size spectrum, to drive a food-web model that estimates the production of sinking zooplankton feces and algal aggregates comprising the sinking particle flux at the base of the euphotic zone. The synthesis of observations and models reveals fundamentally different and ecologically consistent regional-scale patterns in export and export efficiency not found in previous global carbon export assessments. The model reproduces regional-scale particle export field observations and predicts a climatological mean global carbon export from the euphotic zone of ~6 Pg C yr-1. Global export estimates show small variation (typically < 10%) to factor of 2 changes in model parameter values. The model is also robust to the choices of the satellite data products used and enables interannual changes to be quantified. The present synthesis of observations and models provides a path for quantifying the ocean's biological pump.

  5. Natural biogeochemical cycle of mercury in a global three-dimensional ocean tracer model

    NASA Astrophysics Data System (ADS)

    Zhang, Yanxu; Jaeglé, Lyatt; Thompson, LuAnne

    2014-05-01

    We implement mercury (Hg) biogeochemistry in the offline global 3-D ocean tracer model (OFFTRAC) to investigate the natural Hg cycle, prior to any anthropogenic input. The simulation includes three Hg tracers: dissolved elemental (Hg0aq), dissolved divalent (HgIIaq), and particle-bound mercury (HgPaq). Our Hg parameterization takes into account redox chemistry in ocean waters, air-sea exchange of Hg0, scavenging of HgIIaq onto sinking particles, and resupply of HgIIaq at depth by remineralization of sinking particles. Atmospheric boundary conditions are provided by a global simulation of the natural atmospheric Hg cycle in the GEOS-Chem model. In the surface ocean, the OFFTRAC model predicts global mean concentrations of 0.16 pM for total Hg, partitioned as 80% HgIIaq, 14% Hg0aq, and 6% HgPaq. Total Hg concentrations increase to 0.38 pM in the thermocline/intermediate waters (between the mixed layer and 1000 m depth) and 0.82 pM in deep waters (below 1000 m), reflecting removal of Hg from the surface to the subsurface ocean by particle sinking followed by remineralization at depth. Our model predicts that Hg concentrations in the deep North Pacific Ocean (>2000 m) are a factor of 2-3 higher than in the deep North Atlantic Ocean. This is the result of cumulative input of Hg from particle remineralization as deep waters transit from the North Atlantic to the North Pacific on their ~2000 year journey. The model is able to reproduce the relatively uniform concentrations of total Hg observed in the old deep waters of the North Pacific Ocean (observations: 1.2 ± 0.4 pM; model: 1.1 ± 0.04 pM) and Southern Ocean (observations: 1.1 ± 0.2 pM; model: 0.8 ± 0.02 pM). However, the modeled concentrations are factors of 5-6 too low compared to observed concentrations in the surface ocean and in the young water masses of the deep North Atlantic Ocean. This large underestimate for these regions implies a factor of 5-6 anthropogenic enhancement in Hg concentrations.

  6. Global relationship between phytoplankton diversity and productivity in the ocean.

    PubMed

    Vallina, S M; Follows, M J; Dutkiewicz, S; Montoya, J M; Cermeno, P; Loreau, M

    2014-01-01

    The shape of the productivity-diversity relationship (PDR) for marine phytoplankton has been suggested to be unimodal, that is, diversity peaking at intermediate levels of productivity. However, there are few observations and there has been little attempt to understand the mechanisms that would lead to such a shape for planktonic organisms. Here we use a marine ecosystem model together with the community assembly theory to explain the shape of the unimodal PDR we obtain at the global scale. The positive slope from low to intermediate productivity is due to grazer control with selective feeding, which leads to the predator-mediated coexistence of prey. The negative slope at high productivity is due to seasonal blooms of opportunist species that occur before they are regulated by grazers. The negative side is only unveiled when the temporal scale of the observation captures the transient dynamics, which are especially relevant at highly seasonal latitudes. Thus selective predation explains the positive side while transient competitive exclusion explains the negative side of the unimodal PDR curve. The phytoplankton community composition of the positive and negative sides is mostly dominated by slow-growing nutrient specialists and fast-growing nutrient opportunist species, respectively. PMID:24980772

  7. Global coupled ocean-atmosphere general circulation models in LASG/IAP

    NASA Astrophysics Data System (ADS)

    Yongqiang, Yu; Xuehong, Zhang; Yufu, Guo

    2004-06-01

    Coupled ocean-atmospheric general circulation models are the only tools to quantitatively simulate the climate system. Since the end of the 1980s, a group of scientists in the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences (CAS), have been working to develop a global OGCM and a global coupled ocean-atmosphere general circulation model (CGCM). From the original flux anomaly-coupling model developed in the beginning of the 1990s to the latest directly-coupling model, LASG scientists have developed four global coupled GCMs. This study summarizes the development history of these models and describes the third and fourth coupled GCMs and selected applications. Strengths and weaknesses of these models are highlighted.

  8. Seasonal distribution and succession of dominant phytoplankton groups in the global ocean: A satellite view

    NASA Astrophysics Data System (ADS)

    Alvain, S.; Moulin, C.; Dandonneau, Y.; Loisel, H.

    2008-09-01

    Phytoplankton plays an important role in the global carbon cycle via the fixation of inorganic carbon during photosynthesis. However, the efficiency of this "biological pump of carbon" strongly depends on the nature of the phytoplankton. Monitoring spatial and temporal variations of the distribution of dominant phytoplankton groups at the global scale is thus of critical importance. Recently, an algorithm has been developed to detect the major dominant phytoplankton groups from anomalies of the marine signal measured by ocean color satellites. This method, called PHYSAT, allows to identify nanoeucaryotes, Prochlorococcus, Synechococcus and diatoms. In this paper, PHYSAT has been improved to detect an additional group, named phaeocystis-like, by analyzing specific signal anomalies in the Southern Ocean during winter months. This new version of PHYSAT was then used to process daily global SeaWiFS GAC data between 1998 and 2006. The global distribution of major phytoplankton groups is presented in this study as a monthly climatology of the most frequent phytoplankton group. The contribution of nanoeucaryotes-dominated waters to the global ocean varies from 45 to 70% depending on the season, whereas both diatoms and phaeocystis-like contributions exhibit a stronger seasonal variability mostly due to the large blooms that occur during winter in the Southern Ocean. Three regions of particular interest are also studied in more details: the Southern Ocean, the North Atlantic, and the Equatorial Pacific. The North Atlantic diatom bloom shows a large interannual variability. Large blooms of both diatoms and phaeocystis-like are observed during winter in the Southern Ocean, with a larger contribution from diatoms. Their respective geographical distribution is shown to be tightly related to the depth of the mixed-layer, with diatoms prevailing in stratified waters. Synechococcus and Prochloroccocus prevail in the Equatorial Pacific, but our data show also sporadic diatoms

  9. The microbial carbon pump concept: Potential biogeochemical significance in the globally changing ocean

    NASA Astrophysics Data System (ADS)

    Legendre, Louis; Rivkin, Richard B.; Weinbauer, Markus G.; Guidi, Lionel; Uitz, Julia

    2015-05-01

    Three vertical ocean carbon pumps have been known for almost three decades to sequester atmospheric carbon in the deep-water and sediment reservoirs, i.e. the solubility pump, the carbonate pump, and the soft-tissue (also known as organic, or biological) carbon pump (BCP). These three pumps maintain the vertical gradient in total dissolved inorganic carbon between the surface and deep waters. The more recently proposed microbial carbon pump (MCP) would maintain a gradient between short- and long-lived dissolved organic carbon (DOC; average lifetimes of <100 and >100 years, respectively). Long-lived DOC is an additional proposed reservoir of sequestered carbon in the ocean. This review: examines critically aspects of the vertical ocean carbon pumps and the MCP, in particular their physical dimensions and their potential roles in carbon sequestration; normalises the dimensions of the MCP to allow direct comparisons with the three vertical ocean carbon pumps; compares the MCP and vertical ocean carbon pumps; organises in a coherent framework the information available in the literature on refractory DOC; explores the potential effects of the globally changing ocean on the MCP; and identifies the assumptions that generally underlie the MCP studies, as bases for future research. The study: proposes definitions of terms, expressions and concepts related to the four ocean carbon pumps (i.e. three vertical pumps and MCP); defines the magnitude for the MCP as the rate of production of DOC with an average lifetime of >100 years and provides its first estimate for the World Ocean, i.e. 0.2 Pg C year-1; and introduces an operational "first-time-sequestration" criterion that prevents organic carbon fluxes from being assigned to both the BCP and the MCP. In our review of the potential effects of predicted climate-related changes in the ocean environment on the MCP, we found that three of the seven predicted changes could potentially enhance carbon sequestration by the MCP, and

  10. Assessment of storage lipid accumulation patterns in eucalanoid copepods from the eastern tropical Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Cass, Christine J.; Daly, Kendra L.; Wakeham, Stuart G.

    2014-11-01

    Members of the copepod family Eucalanidae are widely distributed throughout the world's oceans and have been noted for their accumulation of storage lipids in high- and low-latitude environments. However, little is known about the lipid composition of eucalanoid copepods in low-latitude environments. The purpose of this study was to examine fatty acid and alcohol profiles in the storage lipids (wax esters and triacylglycerols) of Eucalanus inermis, Rhincalanus rostrifrons, R. nasutus, Pareucalanus attenuatus, and Subeucalanus subtenuis, collected primarily in the eastern tropical north Pacific near the Tehuantepec Bowl and Costa Rica Dome regions, noted for its oxygen minimum zone, during fall 2007 and winter 2008/2009. Adult copepods and particulate material were collected in the upper 50 m and from 200 to 300 m in the upper oxycline. Lipid profiles of particulate matter were generated to help ascertain information on ecological strategies of these species and on differential accumulation of dietary and modified fatty acids in the wax ester and triacylglycerol storage lipid components of these copepods in relation to their vertical distributions around the oxygen minimum zone. Additional data on phospholipid fatty acid and sterol/fatty alcohol fractions were also generated to obtain a comprehensive lipid data set for each sample. Rhincalanus spp. accumulated relatively large amounts of storage lipids (31-80% of dry mass (DM)), while E. inermis had moderate amounts (2-9% DM), and P. attenuatus and S. subtenuis had low quantities of storage lipid (0-1% DM). E. inermis and S. subtenuis primarily accumulated triacylglycerols (>90% of storage lipids), while P. attenuatus and Rhincalanus spp. primarily accumulated wax esters (>84% of storage lipids). Based on previously generated molecular phylogenies of the Eucalanidae family, these results appear to support genetic predisposition as a major factor explaining why a given species accumulates primarily triacylglycerols

  11. In situ imaging reveals the biomass of giant protists in the global ocean.

    PubMed

    Biard, Tristan; Stemmann, Lars; Picheral, Marc; Mayot, Nicolas; Vandromme, Pieter; Hauss, Helena; Gorsky, Gabriel; Guidi, Lionel; Kiko, Rainer; Not, Fabrice

    2016-04-28

    Planktonic organisms play crucial roles in oceanic food webs and global biogeochemical cycles. Most of our knowledge about the ecological impact of large zooplankton stems from research on abundant and robust crustaceans, and in particular copepods. A number of the other organisms that comprise planktonic communities are fragile, and therefore hard to sample and quantify, meaning that their abundances and effects on oceanic ecosystems are poorly understood. Here, using data from a worldwide in situ imaging survey of plankton larger than 600 μm, we show that a substantial part of the biomass of this size fraction consists of giant protists belonging to the Rhizaria, a super-group of mostly fragile unicellular marine organisms that includes the taxa Phaeodaria and Radiolaria (for example, orders Collodaria and Acantharia). Globally, we estimate that rhizarians in the top 200 m of world oceans represent a standing stock of 0.089 Pg carbon, equivalent to 5.2% of the total oceanic biota carbon reservoir. In the vast oligotrophic intertropical open oceans, rhizarian biomass is estimated to be equivalent to that of all other mesozooplankton (plankton in the size range 0.2-20 mm). The photosymbiotic association of many rhizarians with microalgae may be an important factor in explaining their distribution. The previously overlooked importance of these giant protists across the widest ecosystem on the planet changes our understanding of marine planktonic ecosystems. PMID:27096373

  12. A global transition to ferruginous conditions in the early Neoproterozoic oceans

    NASA Astrophysics Data System (ADS)

    Guilbaud, Romain; Poulton, Simon W.; Butterfield, Nicholas J.; Zhu, Maoyan; Shields-Zhou, Graham A.

    2015-06-01

    Eukaryotic life expanded during the Proterozoic eon, 2.5 to 0.542 billion years ago, against a background of fluctuating ocean chemistry. After about 1.8 billion years ago, the global ocean is thought to have been characterized by oxygenated surface waters, with anoxic and sulphidic waters in middle depths along productive continental margins and anoxic and iron-containing (ferruginous) deeper waters. The spatial extent of sulphidic waters probably varied through time, but this surface-to-deep redox structure is suggested to have persisted until the first Neoproterozoic glaciation about 717 million years ago. Here we report an analysis of ocean redox conditions throughout the Proterozoic using new and existing iron speciation and sulphur isotope data from multiple cores and outcrops. We find a global transition from sulphidic to ferruginous mid-depth waters in the earliest Neoproterozoic, coincident with the amalgamation of the supercontinent Rodinia at low latitudes. We suggest that ferruginous conditions were initiated by an increase in the oceanic influx of highly reactive iron relative to sulphate, driven by a change in weathering regime and the uptake of sulphate by extensive continental evaporites on Rodinia. We propose that this transition essentially detoxified ocean margin settings, allowing for expanded opportunities for eukaryote diversification following a prolonged evolutionary stasis before one billion years ago.

  13. Tropical Ocean Global Atmosphere (TOGA) Meteorological and Oceanographic Data Sets for 1985 and 1986

    NASA Technical Reports Server (NTRS)

    Halpern, D.; Ashby, H.; Finch, C.; Smith, E.; Robles, J.

    1990-01-01

    The Tropical Ocean Global Atmosphere (TOGA) Program is a component of the World Meteorological Organization (WMO)/International Council of Scientific Unions (ICSU) World Climate Research Program (WCRP). One of the objectives of TOGA, which began in 1985, is to determine the limits of predictability of monthly mean sea surface temperature variations in tropical regions. The TOGA program created a raison d'etre for an explosive growth of the tropical ocean observing system and a substantial improvement in numerical simulations from atmospheric and oceanic general circulation models. Institutions located throughout the world are involved in the TOGA-distributed active data archive system. The diverse TOGA data sets for 1985 and 1986, including results from general circulation models, are included on a CD-ROM. Variables on the CD-ROM are barometric pressure, surface air temperature, dewpoint temperature Cartesian components of surface wind, surface sensible and latent heat fluxes,Cartesian components of surface wind stress and of an index of surface wind stress, sea level, sea surface temperature, and depth profiles of temperature and current in the upper ocean. Some data sets are global in extent, some are regional and cover portions of an ocean basin. Data on the CD-ROM can be extracted with an Apple Macintosh or an IBM PC.

  14. Regional Comparisons from a Global Survey of Deep-Ocean Sound

    NASA Astrophysics Data System (ADS)

    Haxel, J. H.; Dziak, R. P.; Matsumoto, H.; Lau, T. K.; Mellinger, D. K.; Fowler, M. J.

    2008-12-01

    A NOAA Pacific Marine Environmental Lab archive of continuous deep-ocean sound recordings from hydrophones deployed in the equatorial East Pacific (EEP), central Mid-Atlantic (CMA), northern Mid-Atlantic (NMA), Bering Sea (BS), Antarctic Peninsula (ANP), and Indian Ocean (IO) provides insight into the overall structure for the deep-water global sound field. The hydrophones are moored in the SOFAR channel, taking advantage of the efficient propagation characteristics that enable the instruments to effectively monitor large sections of the global oceans. Although not always concurrent, the deployment of the hydrophone arrays from 1996 to present allows for an up-to-date assessment of the global-scale distribution of ocean sound levels in discrete frequency bands. Comparisons of intra- and inter-annual time-averaged ambient-sound levels reveal strong latitudinal variations, where higher latitudes correspond with higher noise levels. Seismic and volcanic activity dominate the lower frequency bands (0-10 Hz) within all of the hydrophone arrays. Of interest is the periodic nature of broad-band ice noise observed in the ANP acoustic data, suggesting a climate link for these signals related to ice breakup during seasonal warming events (Matsumoto et al., 2008). In addition, the multi-species marine-mammal vocalizations observed in all of our hydrophone datasets dominate sound-energy levels at specific frequencies.

  15. Enceladus's subsurface sea is part of a global ocean as shown by measured physical libration

    NASA Astrophysics Data System (ADS)

    Thomas, P.; Tajeddine, R.; Tiscareno, M. S.; Burns, J. A.; Joseph, J.; Loredo, T. J.; Helfenstein, P.; Porco, C.

    2015-12-01

    The Saturnian satellite Enceladus vigorously vents liquid water and vapor from fractures within a south polar depression. The source appears to be a liquid reservoir rather than active heating, but the extent and location of any subsurface liquid region is not directly observable. We use measurements of control points across the surface of Enceladus from seven years of spacecraft observations to determine the satellite's precise rotation state; we find a forced physical libration of 0.120 ± 0.014° (2σ). This value is too large to be consistent with Enceladus's core being rigidly connected to its ice shell, and thus implies the presence of a global ocean rather than a solitary polar sea. Together with other constraints, our results imply that the global ocean is thin and connected to a thicker sea under the south polar terrain. We present models of the range of shell, ocean, and core sizes consistent with the libration and other geophysical data. The maintenance of a global ocean within Enceladus is problematic according to some thermal models and so may require particular satellite properties or a surprisingly dissipative Saturn.

  16. A 1/16° eddying simulation of the global ocean/sea ice system

    NASA Astrophysics Data System (ADS)

    Iovino, Dorotea; Masina, Simona; Storto, Andrea; Cipollone, Andrea; Stepanov, Vladimir N.

    2016-04-01

    Analysis of a global eddy-resolving simulation using the NEMO general circulation model is presented. The model has 1/16° horizontal spacing at the equator, employs two displaced poles in the Northern Hemisphere, and uses 98 vertical levels. The simulation was spun up from rest and integrated for 11 model years, using ERA-Interim reanalysis as surface forcing. Primary intent of this hindcast is to test how the model represents upper ocean characteristics and sea ice properties. Numerical results show that, overall, the general circulation is well reproduced, with realistic values for overturning mass and heat transports. Analysis of the zonal averaged temperature and salinity, and the mixed layer depth indicate that the model average state is in good agreement with observed fields. Comparisons against observational estimates of mass transports through key straits indicate that most aspects of the model circulation are realistic. As expected, the simulation exhibits turbulent behaviour. The spatial distribution of the sea surface height variability from the model is close to the observed pattern. Despite the increase in resolution, the variability amplitude is still weak, in particular in the Southern Ocean. The distribution and volume of the sea ice are, to a large extent, comparable to observed values. Compared with a corresponding coarse-resolution configuration, the performance of the model is significantly improved, although relatively minor weaknesses still exist. We conclude that the model output is suitable for broader analysis to better understand upper ocean dynamics and ocean variability at global scales. This simulation represents a major step forward in the CMCC global ocean modelling, and constitutes the groundwork for future applications to short-range ocean forecasting.

  17. A comparison of global estimates of marine primary production from ocean color

    NASA Astrophysics Data System (ADS)

    Carr, Mary-Elena; Friedrichs, Marjorie A. M.; Schmeltz, Marjorie; Noguchi Aita, Maki; Antoine, David; Arrigo, Kevin R.; Asanuma, Ichio; Aumont, Olivier; Barber, Richard; Behrenfeld, Michael; Bidigare, Robert; Buitenhuis, Erik T.; Campbell, Janet; Ciotti, Aurea; Dierssen, Heidi; Dowell, Mark; Dunne, John; Esaias, Wayne; Gentili, Bernard; Gregg, Watson; Groom, Steve; Hoepffner, Nicolas; Ishizaka, Joji; Kameda, Takahiko; Le Quéré, Corinne; Lohrenz, Steven; Marra, John; Mélin, Frédéric; Moore, Keith; Morel, André; Reddy, Tasha E.; Ryan, John; Scardi, Michele; Smyth, Tim; Turpie, Kevin; Tilstone, Gavin; Waters, Kirk; Yamanaka, Yasuhiro

    2006-03-01

    The third primary production algorithm round robin (PPARR3) compares output from 24 models that estimate depth-integrated primary production from satellite measurements of ocean color, as well as seven general circulation models (GCMs) coupled with ecosystem or biogeochemical models. Here we compare the global primary production fields corresponding to eight months of 1998 and 1999 as estimated from common input fields of photosynthetically-available radiation (PAR), sea-surface temperature (SST), mixed-layer depth, and chlorophyll concentration. We also quantify the sensitivity of the ocean-color-based models to perturbations in their input variables. The pair-wise correlation between ocean-color models was used to cluster them into groups or related output, which reflect the regions and environmental conditions under which they respond differently. The groups do not follow model complexity with regards to wavelength or depth dependence, though they are related to the manner in which temperature is used to parameterize photosynthesis. Global average PP varies by a factor of two between models. The models diverged the most for the Southern Ocean, SST under 10C, and chlorophyll concentration exceeding 1 mg Chl m-3. Based on the conditions under which the model results diverge most, we conclude that current ocean-color-based models are challenged by high-nutrient low-chlorophyll conditions, and extreme temperatures or chlorophyll concentrations. The GCM-based models predict comparable primary production to those based on ocean color: they estimate higher values in the Southern Ocean, at low SST, and in the equatorial band, while they estimate lower values in eutrophic regions (probably because the area of high chlorophyll concentrations is smaller in the GCMs). Further progress in primary production modeling requires improved understanding of the effect of temperature on photosynthesis and better parameterization of the maximum photosynthetic rate.

  18. Ensemble simulations of the magnetic field induced by global ocean circulation: Estimating the uncertainty

    NASA Astrophysics Data System (ADS)

    Irrgang, Christopher; Saynisch, Jan; Thomas, Maik

    2016-03-01

    The modeling of the ocean global circulation induced magnetic field is affected by various uncertainties that originate from errors in the input data and from the model itself. The amount of aggregated uncertainties and their effect on the modeling of electromagnetic induction in the ocean is unknown. For many applications, however, the knowledge of uncertainties in the modeling is essential. To investigate the uncertainty in the modeling of motional induction at the sea surface, simulation experiments are performed on the basis of different error scenarios and error covariance matrices. For these error scenarios, ensembles of an ocean general circulation model and an electromagnetic induction model are generated. This ensemble-based approach allows to estimate both the spatial distribution and temporal variation of the uncertainty in the ocean-induced magnetic field. The largest uncertainty in the ocean-induced magnetic field occurs in the area of the Antarctic Circumpolar Current. Local maxima reach values of up to 0.7 nT. The estimated global annual mean uncertainty in the ocean-induced magnetic field ranges from 0.1 to 0.4 nT. The relative amount of uncertainty reaches up to 30% of the signal strength with largest values in regions in the northern hemisphere. The major source of uncertainty is found to be introduced by wind stress from the atmospheric forcing of the ocean model. In addition, the temporal evolution of the uncertainty in the induced magnetic field shows distinct seasonal variations. Specific regions are identified which are robust with respect to the introduced uncertainties.

  19. Steady-state and transient modeling of tracer and nutrient distributions in the global ocean

    SciTech Connect

    Stocker, T.F.; Broecker, W.S.

    1992-03-26

    The deep circulation model developed by Wright and Stocker has been used to represent the latitude-depth distributions of temperature, salinity, radiocarbon and color'' tracers in the Pacific, Atlantic and Indian Oceans. Restoring temperature and salinity to observed surface data the model shows a global thermohaline circulation where deep water is formed in the North Atlantic and in the Southern Ocean. A parameter study reveals that the high-latitude surface salinity determines the composition of deep water and its flow in the global ocean. Increasing Southern Ocean surface salinity by 0.4 ppt the circulation changes from a present-day mode where North Atlantic Deep Water is one where Antarctic Bottom Water is dominant. An inorganic carbon cycle with surface carbonate chemistry is included, and gas exchange is parameterized in terms of pCO{sub 2} differences. Pre- industrial conditions are achieved by adjusting the basin-mean alkalinity. A classical 2{times}CO{sub 2} experiment yields the intrinsic time scales for carbon uptake of the ocean; they agree with those obtained from simple box models or 3-dimensional ocean general circulation models. Using the estimated industrial anthropogenic input of CO{sub 2} into the atmosphere the model requires, consistent with other model studies, an additional carbon flux to match the observed increase of atmospheric pCO{sub 2}. We use more realistic surface boundary conditions which reduce sensitivity to freshwater discharges into the ocean. In a glacial-to-interglacial experiment rapid transitions of the deep circulation between two different states occur in conjunction with a severe reduction of the meridional heat flux and sea surface temperature during peak melting. After the melting the conveyor belt circulation restarts.

  20. ECCO2: High Resolution Global Ocean and Sea Ice Data Synthesis

    NASA Astrophysics Data System (ADS)

    Menemenlis, D.; Campin, J.; Heimbach, P.; Hill, C.; Lee, T.; Nguyen, A.; Schodlok, M.; Zhang, H.

    2008-12-01

    The Estimating the Circulation and Climate of the Ocean, Phase II (ECCO2) project aims to produce a best- possible, time-evolving synthesis of most available ocean and sea-ice data at a resolution that permits ocean eddies. ECCO2 analyses are obtained via least squares fit of a global, full-depth-ocean, and sea-ice configuration of the Massachusetts Institute of Technology general circulation model (MITgcm) to the available satellite and in-situ data. What sets apart ECCO2 analyses from operational high-resolution ocean data assimilation products is their physical consistency; the analyses do not contain discontinuities when and where data are ingested. ECCO2 analyses are intended to help quantify the role of the oceans in the global carbon cycle, to understand the recent evolution of the polar oceans, to monitor time-evolving term balances within and between different components of the Earth system, and for many other science applications. A first ECCO2 analysis for the 1992-2007 period has been obtained using a Green's Function approach to estimate initial temperature and salinity conditions, surface boundary conditions, and several empirical model parameters. Data constraints include altimetry, gravity, drifter, hydrographic, and sea-ice data. A large complement of high-frequency and high-resolution diagnostics has been saved; these diagnostics are made available to the scientific community via ftp and OPeNDAP servers at http://ecco2.org. This presentation provides a brief overview of this first ECCO2 analysis, of the estimation methodology, of the solution characteristics, and of some early science applications.

  1. A parallel Atmosphere-Ocean Global Circulation Model of intermediate complexity for Earth system climate research

    NASA Astrophysics Data System (ADS)

    Silva, T. A.; Schmittner, A.

    2007-12-01

    We present the evolution of an Earth System model of intermediate complexity featuring an ocean global circulation model to include a fully coupled 3D primitive equations atmospheric model. The original Earth System climate model, UVic ESCM (Weaver et al. 2001), uses an ocean global circulation model coupled to a one layer atmospheric energy-moisture balance model. It also comprises a viscous-plastic rheology sea ice model, a mechanical land ice model, land surface, oceanic and terrestrial carbon models and a simple 3D marine ecosystem model (Schmittner et al. 2005). A spectral atmospheric, model, PUMA (Fraedrich et al. 2005), was coupled to the UVic ESCM to provide an atmosphere with nonlinear dynamics in target resolutions of T21, T31 and T42, as required. The coupling with the atmosphere, which involves data transfer, preprocessing and interpolation, is done through the OASIS3 coupler. During a run there are 2 + 2N parallel processes: the UVic ESCM, the Oasis3 coupler and the PUMA model with its domain split across 2N processes. The choice of N allows to balance more or less complex configurations of UVic model (e.g. higher level marine ecosystem model or number of biogeochemical tracers) with the atmospheric model at different resolutions, in order to maintain computational efficiency. The relatively simple parameterizations make this new atmosphere-ocean global circulation model much faster than a state-of-the-art Atmosphere-Ocean Global Circulation Model, and so optimally geared for decadal to millennial scale integrations. The latter require special care with the conservation of fluxes during coupling. A second order conservative interpolation method was applied (Jones 1999) and this is compared with the use of typical non-conservative methods.

  2. Remote-sensing-based measurement of phytoplankton size spectrum and cell diameter in the global oceans

    NASA Astrophysics Data System (ADS)

    Roy, S.; Sathyendranath, S.; Bouman, H. A.; Platt, T.

    2012-12-01

    Oceanic phytoplankton regulate the spectral quality of the submarine light field because light absorption by phytoplankton is spectrally structured, with a maximum in the blue and a secondary maximum in the red. The spectral characteristics of absorption are variable with phytoplankton taxa, and also with cell size and growth conditions. The intra-cellular concentration of light-absorbing pigments varies with phytoplankton size, which in turn modulates its specific absorption. The changes in phytoplankton cell size alter not only the bio-optical properties of the water column, but also the trophic interactions within the ecosystem. It is thus important to study the time evolution of phytoplankton size structure over the global ocean. We have developed a novel model that uses the light absorption coefficient of phytoplankton to retrieve quantitative information about phytoplankton size structure from satellite-derived ocean-colour data. The application of the method to satellite remote sensing at any given spatial location depends on the estimates of the concentration of chlorophyll-a, which is an operational index of phytoplankton biomass, and the remote sensing reflectance at different wavelengths in the visible domain. Using our method we have computed the equivalent spherical diameter of phytoplankton cells and the exponent of particle-size spectrum of phytoplankton, and thereby estimated the chlorophyll distribution in different phytoplankton size classes on a global scale. The spatial distribution of the size-spectrum exponent and the biomass fractions of pico-, nano- and micro-phytoplankton estimated are consistent with our current understanding of phytoplankton functional types in the global oceans. The study will enhance our understanding of the distribution and time evolution of phytoplankton size structure in the global oceans.

  3. A Multilayer Dataset of SSM/I-Derived Global Ocean Surface Turbulent Fluxes

    NASA Technical Reports Server (NTRS)

    Chou, Shu-Hsien; Shie, Chung-Lin; Atlas, Robert M.; Ardizzone, Joe; Nelkin, Eric; Einaud, Franco (Technical Monitor)

    2001-01-01

    A dataset including daily- and monthly-mean turbulent fluxes (momentum, latent heat, and sensible heat) and some relevant parameters over global oceans, derived from the Special Sensor Microwave/Imager (SSM/I) data, for the period July 1987-December 1994 and the 1988-94 annual and monthly-mean climatologies of the same variables is created. It has a spatial resolution of 2.0deg x 2.5deg latitude-longitude. The retrieved surface air humidity is found to be generally accurate as compared to the collocated radiosonde observations over global oceans. The retrieved wind stress and latent heat flux show useful accuracy as verified against research quality measurements of ship and buoy in the western equatorial Pacific. The 1988-94 seasonal-mean wind stress and latent heat flux show reasonable patterns related to seasonal variations of the atmospheric general circulation. The patterns of 1990-93 annual-mean turbulent fluxes and input variables are generally in good agreement with one of the best global analyzed flux datasets that based on COADS (comprehensive ocean-atmosphere data set) with corrections on wind speeds and covered the same period. The retrieved wind speed is generally within +/-1 m/s of the COADS-based, but is stronger by approx. 1-2 m/s in the northern extratropical oceans. The discrepancy is suggested to be mainly due to higher COADS-modified wind speeds resulting from underestimation of anemometer heights. Compared to the COADS-based, the retrieved latent heat flux and sea-air humidity difference are generally larger with significant differences in the trade wind zones and the ocean south of 40degS (up to approx. 40-60 W/sq m and approx. 1-1.5 g/kg). The discrepancy is believed to be mainly caused by higher COADS-based surface air humidity arising from the overestimation of dew point temperatures and from the extrapolation of observed high humidity southward into data-void regions south of 40degS. The retrieved sensible heat flux is generally within +/-5

  4. Warm tropical ocean surface and global anoxia during the mid-Cretaceous period.

    PubMed

    Wilson, P A; Norris, R D

    2001-07-26

    The middle of the Cretaceous period (about 120 to 80 Myr ago) was a time of unusually warm polar temperatures, repeated reef-drowning in the tropics and a series of oceanic anoxic events (OAEs) that promoted both the widespread deposition of organic-carbon-rich marine sediments and high biological turnover. The cause of the warm temperatures is unproven but widely attributed to high levels of atmospheric greenhouse gases such as carbon dioxide. In contrast, there is no consensus on the climatic causes and effects of the OAEs, with both high biological productivity and ocean 'stagnation' being invoked as the cause of ocean anoxia. Here we show, using stable isotope records from multiple species of well-preserved foraminifera, that the thermal structure of surface waters in the western tropical Atlantic Ocean underwent pronounced variability about 100 Myr ago, with maximum sea surface temperatures 3-5 degrees C warmer than today. This variability culminated in a collapse of upper-ocean stratification during OAE-1d (the 'Breistroffer' event), a globally significant period of organic-carbon burial that we show to have fundamental, stratigraphically valuable, geochemical similarities to the main OAEs of the Mesozoic era. Our records are consistent with greenhouse forcing being responsible for the warm temperatures, but are inconsistent both with explanations for OAEs based on ocean stagnation, and with the traditional view (reviewed in ref. 12) that past warm periods were more stable than today's climate. PMID:11473314

  5. The change in oceanic O2 inventory associated with recent global warming

    PubMed Central

    Keeling, Ralph F.; Garcia, Hernan E.

    2002-01-01

    Oceans general circulation models predict that global warming may cause a decrease in the oceanic O2 inventory and an associated O2 outgassing. An independent argument is presented here in support of this prediction based on observational evidence of the ocean's biogeochemical response to natural warming. On time scales from seasonal to centennial, natural O2 flux/heat flux ratios are shown to occur in a range of 2 to 10 nmol of O2 per joule of warming, with larger ratios typically occurring at higher latitudes and over longer time scales. The ratios are several times larger than would be expected solely from the effect of heating on the O2 solubility, indicating that most of the O2 exchange is biologically mediated through links between heating and stratification. The change in oceanic O2 inventory through the 1990s is estimated to be 0.3 ± 0.4 × 1014 mol of O2 per year based on scaling the observed anomalous long-term ocean warming by natural O2 flux/heating ratios and allowing for uncertainty due to decadal variability. Implications are discussed for carbon budgets based on observed changes in atmospheric O2/N2 ratio and based on observed changes in ocean dissolved inorganic carbon. PMID:12048249

  6. The Change in Oceanic O2 Inventory Associated with Recent Global Warming

    NASA Technical Reports Server (NTRS)

    Keeling, Ralph; Garcia, Hernan

    2002-01-01

    Oceans general circulation models predict that global warming may cause a decrease in the oceanic O2 inventory and an associated O2 outgassing. An independent argument is presented here in support of this prediction based on observational evidence of the ocean's biogeochemical response to natural warming. On time scales from seasonal to centennial, natural O2 flux/heat flux ratios are shown to occur in a range of 2 to 10 nmol O2 per Joule of warming, with larger ratios typically occurring at higher latitudes and over longer time scales. The ratios are several times larger than would be expected solely from the effect of heating on the O2 solubility, indicating that most of the O2 exchange is biologically mediated through links between heating and stratification. The change in oceanic O2 inventory through the 1990's is estimated to be 0.3 - 0.4 x 10(exp 14) mol O2 per year based on scaling the observed anomalous long-term ocean warming by natural O2 flux/heating ratios and allowing for uncertainty due to decadal variability. Implications are discussed for carbon budgets based on observed changes in atmospheric O2/N2 ratio and based on observed changes in ocean dissolved inorganic carbon.

  7. Warm tropical ocean surface and global anoxia during the mid-Cretaceous period

    NASA Astrophysics Data System (ADS)

    Wilson, Paul A.; Norris, Richard D.

    2001-07-01

    The middle of the Cretaceous period (about 120 to 80Myr ago) was a time of unusually warm polar temperatures, repeated reef-drowning in the tropics and a series of oceanic anoxic events (OAEs) that promoted both the widespread deposition of organic-carbon-rich marine sediments and high biological turnover. The cause of the warm temperatures is unproven but widely attributed to high levels of atmospheric greenhouse gases such as carbon dioxide. In contrast, there is no consensus on the climatic causes and effects of the OAEs, with both high biological productivity and ocean `stagnation' being invoked as the cause of ocean anoxia. Here we show, using stable isotope records from multiple species of well-preserved foraminifera, that the thermal structure of surface waters in the western tropical Atlantic Ocean underwent pronounced variability about 100Myr ago, with maximum sea surface temperatures 3-5°C warmer than today. This variability culminated in a collapse of upper-ocean stratification during OAE-1d (the `Breistroffer' event), a globally significant period of organic-carbon burial that we show to have fundamental, stratigraphically valuable, geochemical similarities to the main OAEs of the Mesozoic era. Our records are consistent with greenhouse forcing being responsible for the warm temperatures, but are inconsistent both with explanations for OAEs based on ocean stagnation, and with the traditional view (reviewed in ref. 12) that past warm periods were more stable than today's climate.

  8. Decadal variability of the Tropical Atlantic Ocean Surface Temperature in shipboard measurements and in a Global Ocean-Atmosphere model

    NASA Technical Reports Server (NTRS)

    Mehta, Vikram M.; Delworth, Thomas

    1995-01-01

    Sea surface temperature (SST) variability was investigated in a 200-yr integration of a global model of the coupled oceanic and atmospheric general circulations developed at the Geophysical Fluid Dynamics Laboratory (GFDL). The second 100 yr of SST in the coupled model's tropical Atlantic region were analyzed with a variety of techniques. Analyses of SST time series, averaged over approximately the same subregions as the Global Ocean Surface Temperature Atlas (GOSTA) time series, showed that the GFDL SST anomalies also undergo pronounced quasi-oscillatory decadal and multidecadal variability but at somewhat shorter timescales than the GOSTA SST anomalies. Further analyses of the horizontal structures of the decadal timescale variability in the GFDL coupled model showed the existence of two types of variability in general agreement with results of the GOSTA SST time series analyses. One type, characterized by timescales between 8 and 11 yr, has high spatial coherence within each hemisphere but not between the two hemispheres of the tropical Atlantic. A second type, characterized by timescales between 12 and 20 yr, has high spatial coherence between the two hemispheres. The second type of variability is considerably weaker than the first. As in the GOSTA time series, the multidecadal variability in the GFDL SST time series has approximately opposite phases between the tropical North and South Atlantic Oceans. Empirical orthogonal function analyses of the tropical Atlantic SST anomalies revealed a north-south bipolar pattern as the dominant pattern of decadal variability. It is suggested that the bipolar pattern can be interpreted as decadal variability of the interhemispheric gradient of SST anomalies. The decadal and multidecadal timescale variability of the tropical Atlantic SST, both in the actual and in the GFDL model, stands out significantly above the background 'red noise' and is coherent within each of the time series, suggesting that specific sets of

  9. A Global Ocean Tide Model From TOPEX/POSEIDON Altimetry: GOT99.2

    NASA Technical Reports Server (NTRS)

    Ray, Richard D.

    1999-01-01

    Goddard Ocean Tide model GOT99.2 is a new solution for the amplitudes and phases of the global oceanic tides, based on over six years of sea-surface height measurements by the TOPEX/POSEIDON satellite altimeter. Comparison with deep-ocean tide-gauge measurements show that this new tidal solution is an improvement over previous global models, with accuracies for the main semidiurnal lunar constituent M2 now below 1.5 cm (deep water only). The new solution benefits from use of prior hydrodynamic models, several in shallow and inland seas as well as the global finite-element model FES94.1. This report describes some of the data processing details involved in handling the altimetry, and it provides a comprehensive set of global cotidal charts of the resulting solutions. Various derived tidal charts are also provided, including tidal loading deformation charts, tidal gravimetric charts, and tidal current velocity (or transport) charts. Finally, low-degree spherical harmonic coefficients are computed by numerical quadrature and are tabulated for the major short-period tides; these are useful for a variety of geodetic and geophysical purposes, especially in combination with similar estimates from satellite laser ranging.

  10. Sensitivity of Simulated Global Ocean Carbon Flux Estimates to Forcing by Reanalysis Products

    NASA Technical Reports Server (NTRS)

    Gregg, Watson W.; Casey, Nancy W.; Rousseaux, Cecile S.

    2015-01-01

    Reanalysis products from MERRA, NCEP2, NCEP1, and ECMWF were used to force an established ocean biogeochemical model to estimate air-sea carbon fluxes (FCO2) and partial pressure of carbon dioxide (pCO2) in the global oceans. Global air-sea carbon fluxes and pCO2 were relatively insensitive to the choice of forcing reanalysis. All global FCO2 estimates from the model forced by the four different reanalyses were within 20% of in situ estimates (MERRA and NCEP1 were within 7%), and all models exhibited statistically significant positive correlations with in situ estimates across the 12 major oceanographic basins. Global pCO2 estimates were within 1% of in situ estimates with ECMWF being the outlier at 0.6%. Basin correlations were similar to FCO2. There were, however, substantial departures among basin estimates from the different reanalysis forcings. The high latitudes and tropics had the largest ranges in estimated fluxes among the reanalyses. Regional pCO2 differences among the reanalysis forcings were muted relative to the FCO2 results. No individual reanalysis was uniformly better or worse in the major oceanographic basins. The results provide information on the characterization of uncertainty in ocean carbon models due to choice of reanalysis forcing.

  11. Robust global ocean cooling trend for the pre-industrial Common Era

    NASA Astrophysics Data System (ADS)

    McGregor, Helen V.; Evans, Michael N.; Goosse, Hugues; Leduc, Guillaume; Martrat, Belen; Addison, Jason A.; Mortyn, P. Graham; Oppo, Delia W.; Seidenkrantz, Marit-Solveig; Sicre, Marie-Alexandrine; Phipps, Steven J.; Selvaraj, Kandasamy; Thirumalai, Kaustubh; Filipsson, Helena L.; Ersek, Vasile

    2015-09-01

    The oceans mediate the response of global climate to natural and anthropogenic forcings. Yet for the past 2,000 years -- a key interval for understanding the present and future climate response to these forcings -- global sea surface temperature changes and the underlying driving mechanisms are poorly constrained. Here we present a global synthesis of sea surface temperatures for the Common Era (CE) derived from 57 individual marine reconstructions that meet strict quality control criteria. We observe a cooling trend from 1 to 1800 CE that is robust against explicit tests for potential biases in the reconstructions. Between 801 and 1800 CE, the surface cooling trend is qualitatively consistent with an independent synthesis of terrestrial temperature reconstructions, and with a sea surface temperature composite derived from an ensemble of climate model simulations using best estimates of past external radiative forcings. Climate simulations using single and cumulative forcings suggest that the ocean surface cooling trend from 801 to 1800 CE is not primarily a response to orbital forcing but arises from a high frequency of explosive volcanism. Our results show that repeated clusters of volcanic eruptions can induce a net negative radiative forcing that results in a centennial and global scale cooling trend via a decline in mixed-layer oceanic heat content.

  12. Atmospheric fluxes of organic N and P to the global ocean

    NASA Astrophysics Data System (ADS)

    Kanakidou, Maria; Duce, Robert A.; Prospero, Joseph M.; Baker, Alex R.; Benitez-Nelson, Claudia; Dentener, Frank J.; Hunter, Keith A.; Liss, Peter S.; Mahowald, Natalie; Okin, Gregory S.; Sarin, Manmohan; Tsigaridis, Kostas; Uematsu, Mitsuo; Zamora, Lauren M.; Zhu, Tong

    2012-09-01

    The global tropospheric budget of gaseous and particulate non-methane organic matter (OM) is re-examined to provide a holistic view of the role that OM plays in transporting the essential nutrients nitrogen and phosphorus to the ocean. A global 3-dimensional chemistry-transport model was used to construct the first global picture of atmospheric transport and deposition of the organic nitrogen (ON) and organic phosphorus (OP) that are associated with OM, focusing on the soluble fractions of these nutrients. Model simulations agree with observations within an order of magnitude. Depending on location, the observed water soluble ON fraction ranges from ˜3% to 90% (median of ˜35%) of total soluble N in rainwater; soluble OP ranges from ˜20-83% (median of ˜35%) of total soluble phosphorus. The simulations suggest that the global ON cycle has a strong anthropogenic component with ˜45% of the overall atmospheric source (primary and secondary) associated with anthropogenic activities. In contrast, only 10% of atmospheric OP is emitted from human activities. The model-derived present-day soluble ON and OP deposition to the global ocean is estimated to be ˜16 Tg-N/yr and ˜0.35 Tg-P/yr respectively with an order of magnitude uncertainty. Of these amounts ˜40% and ˜6%, respectively, are associated with anthropogenic activities, and 33% and 90% are recycled oceanic materials. Therefore, anthropogenic emissions are having a greater impact on the ON cycle than the OP cycle; consequently increasing emissions may increase P-limitation in the oligotrophic regions of the world's ocean that rely on atmospheric deposition as an important nutrient source.

  13. Declining Global Per Capita Agricultural Production and Warming Oceans Threaten Food Security

    NASA Technical Reports Server (NTRS)

    Funk, Chris C.; Brown, Molly E.

    2009-01-01

    Despite accelerating globalization, most people still eat food that was grown locally. Developing countries with weak purchasing power tend to import as little food as possible from global markets, suffering consumption deficits during times of high prices or production declines. Local agricultural production, therefore, is critical to both food security and economic development among the rural poor. The level of local agricultural production, in turn, will be controlled by the amount and quality of arable land, the amount and quality of agricultural inputs (fertilizer, seeds, pesticides, etc.), as well as farm-related technology, practices, and policies. In this paper we discuss several emerging threats to global and regional food security, including declining yield gains that are failing to keep up with population increases, and warming in the tropical Indian Ocean and its impact on rainfall. If yields continue to grow more slowly than per capita harvested area, parts of Africa, Asia, and Central and Southern America will experience substantial declines in per capita cereal production. Global per capita cereal production will potentially decline by 14 percent between 2008 and 2030. Climate change is likely to further affect food production, particularly in regions that have very low yields due to lack of technology. Drought, caused by anthropogenic warming in the Indian and Pacific Oceans, may also reduce 21 st century food availability by disrupting Indian Ocean moisture transports and tilting the 21 st century climate toward a more El Nino-like state. The impacts of these circulation changes over Asia remain uncertain. For Africa, however, Indian Ocean warming appears to have already reduced main growing season rainfall along the eastern edge of tropical Africa, from southern Somalia to northern parts of the Republic of South Africa. Through a combination of quantitative modeling of food balances and an examination of climate change, we present an analysis of

  14. Are Salps A Silver Bullet Against Global Warming And Ocean Acidification?

    NASA Astrophysics Data System (ADS)

    Kithil, P. W.

    2006-12-01

    solar panel to power communications & provide remote control. Adjacent pumps are connected at the bottom to maintain relative position. If required, periodic seafloor anchoring can maintain absolute position within an ocean basin. Deployment is low cost as the pumps self-deploy when dropped into the ocean from barges. Pumps would not be deployed in ocean shipping channels, regions used by recreational boaters, nor where excessive tides or currents exist. In a global application, 1,340 arrays each 100,000 km2 are needed to cover the 134 million km2 calculated above. Assuming one pump per square km costing 2,000, an investment of 268 billion is needed. Using a five year payback, this investment is recouped if the carbon credit price is 26.80 per ton applied to sequestering 1.96 billion tons per year of carbon. This is not dramatically different from today's carbon credit price of about 15 per ton. Assuming a governmental mandate of carbon sequestration, today's price could easily increase many-fold, making ocean sequestration using forced upwelling economically attractive. Additional benefits of widespread forced upwelling include: 1 Buffering of ocean pH by removing CO2 during photosynthesis; 2 Possible cooling the upper mixed layer upstream from coral reefs to reduce bleaching from ocean hotspots; 3 Possible mitigation of rapid climate change by enhancing the mixing of arctic/Greenland meltwater; 4 Enhancement of wild fish populations; and, 5 Reduced hurricane intensity, achieved by cooling the upper mixed layer upon approach of a tropical storm in high risk regions such as the Gulf of Mexico.

  15. Heat fluxes of the Indian Ocean from a global eddy-resolving model

    NASA Astrophysics Data System (ADS)

    Garternicht, U.; Schott, F.

    1997-09-01

    The output of the global eddy-resolving ¼° ocean model of Semtner/Chervin (run by the Naval Postgraduate School, Monterey, California) has been used to study the oceanic temperature and heat flux in the Indian Ocean. The meridional heat flux in the northern Indian Ocean is at the low end of the observed values. A vertical overturning cell in the upper 500 m is the main contributor to the annual mean meridional heat flux across 5°S, whereas the horizontal gyre circulation, confined to the upper 500 m, dominates north of the equator. The change of monsoon winds is manifested in a reversal of the meridional circulation throughout the whole water column. The most notable result is a strong linear relationship of the meridional temperature flux and the zonal wind stress component north of 20°S. The model's Pacific-Indian Ocean throughflow across the section at 120°E accounts for -8.8±5.1 Sv (1 Sv≡106 m3 s-1). A strong interannual variability during the model run of 3 years shows a maximum range of 12 Sv in January/February and a minimum during March through June. The inflow from the Pacific into the Indian Ocean results in a total annual mean temperature flux of -0.9 PW (1 PW≡1015 W). In the model the temperature flux from the Pacific through the Indian Ocean to the south dominates in comparison with the input of solar heat from the northern Indian Ocean.

  16. Ocean plankton. Determinants of community structure in the global plankton interactome.

    PubMed

    Lima-Mendez, Gipsi; Faust, Karoline; Henry, Nicolas; Decelle, Johan; Colin, Sébastien; Carcillo, Fabrizio; Chaffron, Samuel; Ignacio-Espinosa, J Cesar; Roux, Simon; Vincent, Flora; Bittner, Lucie; Darzi, Youssef; Wang, Jun; Audic, Stéphane; Berline, Léo; Bontempi, Gianluca; Cabello, Ana M; Coppola, Laurent; Cornejo-Castillo, Francisco M; d'Ovidio, Francesco; De Meester, Luc; Ferrera, Isabel; Garet-Delmas, Marie-José; Guidi, Lionel; Lara, Elena; Pesant, Stéphane; Royo-Llonch, Marta; Salazar, Guillem; Sánchez, Pablo; Sebastian, Marta; Souffreau, Caroline; Dimier, Céline; Picheral, Marc; Searson, Sarah; Kandels-Lewis, Stefanie; Gorsky, Gabriel; Not, Fabrice; Ogata, Hiroyuki; Speich, Sabrina; Stemmann, Lars; Weissenbach, Jean; Wincker, Patrick; Acinas, Silvia G; Sunagawa, Shinichi; Bork, Peer; Sullivan, Matthew B; Karsenti, Eric; Bowler, Chris; de Vargas, Colomban; Raes, Jeroen

    2015-05-22

    Species interaction networks are shaped by abiotic and biotic factors. Here, as part of the Tara Oceans project, we studied the photic zone interactome using environmental factors and organismal abundance profiles and found that environmental factors are incomplete predictors of community structure. We found associations across plankton functional types and phylogenetic groups to be nonrandomly distributed on the network and driven by both local and global patterns. We identified interactions among grazers, primary producers, viruses, and (mainly parasitic) symbionts and validated network-generated hypotheses using microscopy to confirm symbiotic relationships. We have thus provided a resource to support further research on ocean food webs and integrating biological components into ocean models. PMID:25999517

  17. Marine foods sourced from farther as their use of global ocean primary production increases

    PubMed Central

    Watson, Reg A.; Nowara, Gabrielle B.; Hartmann, Klaas; Green, Bridget S.; Tracey, Sean R.; Carter, Chris G.

    2015-01-01

    The growing human population must be fed, but historic land-based systems struggle to meet expanding demand. Marine production supports some of the world's poorest people but increasingly provides for the needs of the affluent, either directly by fishing or via fodder-based feeds for marine and terrestrial farming. Here we show the expanding footprint of humans to utilize global ocean productivity to feed themselves. Our results illustrate how incrementally each year, marine foods are sourced farther from where they are consumed and moreover, require an increasing proportion of the ocean's primary productivity that underpins all marine life. Though mariculture supports increased consumption of seafood, it continues to require feeds based on fully exploited wild stocks. Here we examine the ocean's ability to meet our future demands to 2100 and find that even with mariculture supplementing near-static wild catches our growing needs are unlikely to be met without significant changes. PMID:26079714

  18. Global root zone storage capacity from satellite-based evaporation data

    NASA Astrophysics Data System (ADS)

    Wang-Erlandsson, Lan; Bastiaanssen, Wim; Gao, Hongkai; Jägermeyr, Jonas; Senay, Gabriel; van Dijk, Albert; Guerschman, Juan; Keys, Patrick; Gordon, Line; Savenije, Hubert

    2016-04-01

    We present an "earth observation-based" method for estimating root zone storage capacity - a critical, yet uncertain parameter in hydrological and land surface modelling. By assuming that vegetation optimises its root zone storage capacity to bridge critical dry periods, we were able to use state-of-the-art satellite-based evaporation data computed with independent energy balance equations to derive gridded root zone storage capacity at global scale. This approach does not require soil or vegetation information, is model independent, and is in principle scale-independent. In contrast to traditional look-up table approaches, our method captures the variability in root zone storage capacity within land cover type, including in rainforests where direct measurements of root depth otherwise are scarce. Implementing the estimated root zone storage capacity in the global hydrological model STEAM improved evaporation simulation overall, and in particular during the least evaporating months in sub-humid to humid regions with moderate to high seasonality. We find that evergreen forests are able to create a large storage to buffer for extreme droughts (with a return period of up to 60 years), in contrast to short vegetation and crops (which seem to adapt to a drought return period of about 2 years). The presented method to estimate root zone storage capacity eliminates the need for soils and rooting depth information, which could be a game-changer in global land surface modelling.

  19. Relating GRACE terrestrial water storage variations to global fields of atmospheric forcing

    NASA Astrophysics Data System (ADS)

    Humphrey, Vincent; Gudmundsson, Lukas; Isabelle Seneviratne, Sonia

    2015-04-01

    Synoptic, seasonal and inter-annual fluctuations in atmospheric dynamics all influence terrestrial water storage, with impacts on ecosystems functions, human activities and land-climate interactions. Here we explore to which degree atmospheric variables can explain GRACE estimates of terrestrial water storage on different time scales. Since 2012, the most recent GRACE gravity field solutions (Release 05) can be used to monitor global changes in terrestrial water storage with an unprecedented level of accuracy over more than a decade. In addition, the release of associated gridded and post-processed products facilitates comparisons with other global datasets such as land surface model outputs or satellite observations. We investigate how decadal trends, inter-annual fluctuations as well as monthly anomalies of the seasonal cycle of terrestrial water storage can be related to fields of atmospheric forcing, including e.g. precipitation and temperature as estimated in global reanalysis products using statistical techniques. In the majority of the locations with high signal to noise ratio, both short and long-term fluctuations of total terrestrial water storage can be reconstructed to a large degree based on available atmospheric forcing. However, in some locations atmospheric forcing alone is not sufficient to explain the total change in water storage, suggesting strong influence of other processes. Within that framework, the question of an amplification or attenuation of atmospheric forcing through land-surface feedbacks and changes in long term water storage is discussed, also with respect to uncertainties and potential systematic biases in the results.

  20. The global Mercator Ocean analysis and forecasting high resolution system and its main future updates

    NASA Astrophysics Data System (ADS)

    Lellouche, Jean-Michel; Legalloudec, Olivier; Bourdallé-Badie, Romain; Garric, Gilles; Greiner, Eric; Drévillon, Marie; Regnier, Charly; Testut, Charles-Emmanuel; Benkiran, Mounir; Drillet, Yann

    2015-04-01

    In April 2013, Mercator Ocean has performed a major upgrade of the global 1/12° high resolution system. This system currently delivers daily services, and includes numerous improvements related to the ocean/sea-ice model and the assimilation scheme. Observations are assimilated by means of a reduced-order Kalman filter with a 3D multivariate modal decomposition of the forecast error. It includes an adaptive-error estimate and a localization algorithm. Altimeter data, satellite Sea Surface Temperature and in situ temperature and salinity vertical profiles are jointly assimilated to estimate the initial conditions for numerical ocean forecasting. A 3D-Var scheme provides a correction for the slowly-evolving large-scale biases in temperature and salinity. In April 2015, Mercator Ocean will open the Copernicus Marine Environment Monitoring Service and will be in charge of the global ocean at eddy resolving resolution. In this context, R&D activities conducted during the end of the MyOcean2 and MyOcean follow-on projects to deliver an improved version of the global system will continue throughout 2015. The main new updates we plan to integrate in the next version of the global system concern: 1) A new vertical mixing scheme k-epsilon: vertical physics has been explored with a special focus on the turbulent closure problem to improve the representation of temperature and salinity in the Mixed Layer Depth. 2) An adaptive tuning of observations errors: as the prescription of observation errors in the assimilation systems is often too approximate, some diagnostics have been developed. These diagnostics consist in the computation of the Desroziers ratio which is a function of observation errors, innovations and residuals. It helps to identify inconsistency on the specified observation errors and to tune an adaptive weight coefficient acting on the error of each assimilated observation. 3) The assimilation of sea-ice concentration observations: it is introduced in the

  1. Determination of stability and instability of oceanic processes on a global scale using satellite measurements

    NASA Astrophysics Data System (ADS)

    Shevyrnogov, Anatoly; Vysotskaya, Galina

    According to different estimates from the mid-nineteenth century the average surface temper-ature has increased by 0.3-0.6o C. In different parts of the Earth this warming is manifested in varying degrees, but almost anywhere the temperature increase by itself did not have catas-trophic effects on ecosystems and human activity. Extreme climatic events have a much greater influence on the environment. The Global Ocean is the largest part of the biosphere of the Earth, and, thus, investigation of chlorophyll concentration dynamics is extremely important for studying global carbon cycles. In this paper we propose a generalized approach to the study of dynamics of the "ocean-atmosphere" system using the methods of statistical evaluation of long-term series of satellite (AVHRR, SeaWiFS and MODIS) and ground-true data, based on the theory of stochastic dynamic systems. To study the dynamics of the ocean for the period from 1985 through 2008 we used data on the temperature of the surface layer of the ocean and chlorophyll concentration because it is a good indicator of how atmospheric and oceanic processes. As it is known a priori that extremely high and extremely low chlorophyll concen-trations or sea surface temperature are associated with different physical processes, when mean or total biomass in the ocean is calculated, the processes induced by different physical reasons superpose. Thus, no correlation can be reached between the calculated total dynamics and some physical process. In this paper we applied the method of statistical distribution analysis of data to every pixel. With this approach, extreme values are investigated in greater detail. We divided the range of values for every pixel into 5 parts; seasonal variations were taken into account. The spatiotemporal distribution of the dynamics of extreme and average values was investigated. This approach made possible discovering the commonality of processes in the different oceans and defining a problem of

  2. Global Biogeochemical Fluxes Program for the Ocean Observatories Initiative: A Proposal. (Invited)

    NASA Astrophysics Data System (ADS)

    Ulmer, K. M.; Taylor, C.

    2010-12-01

    The overarching emphasis of the Global Biogeochemical Flux Ocean Observatories Initiative is to assess the role of oceanic carbon, both living and non-, in the Earth climate system. Modulation of atmospheric CO2 and its influence on global climate is a function of the quantitative capacity of the oceans to sequester organic carbon into deep waters. Critical to our understanding of the role of the oceans in the global cycling of carbon are the quantitative dynamics in both time and space of the fixation of CO2 into organic matter by surface ocean primary production and removal of this carbon to deep waters via the “biological pump”. To take the next major step forward in advancing our understanding of the oceanic biological pump, a global observation program is required that: (i) greatly improves constraints on estimates of global marine primary production (PP), a critical factor in understanding the global CO2 cycle and for developing accurate estimates of export production (EP); (ii) explores the spatiotemporal links between PP, EP and the biogeochemical processes that attenuate particulate organic carbon (POC) flux; (iii) characterizes microbial community structure and dynamics both in the surface and deep ocean; (iv) develops a comprehensive picture of the chemical and biological processes that take place from the surface ocean to the sea floor; (v) provides unique time-series samples for detailed laboratory-based chemical and biological characterization and tracer studies that will enable connections to be made between the operation of the biological pump at present and in the geologic past. The primary goal is to provide high quality biological and biogeochemical observational data for the modeling and prediction efforts of the global CO2 cycle research community. Crucial to the realization of the GBF-OOI is the development of reliable, long-term, time-series ocean observation platforms capable of precise

  3. What can we learn from the inter-comparison of global ocean observing systems from an Argo perspective?

    NASA Astrophysics Data System (ADS)

    von Schuckmann, Karina; Chambers, Don; Sallée, Jean-Baptiste; Cabanes, Cecile; Le Traon, Pierre-Yves; Speich, Sabrina; Gaillard, Fabienne; Hamon, Mathieu

    2013-04-01

    One of the Argo Program's most important contributions to climate science is an improvement in estimations of heat stored by the oceans and its associated volume changes, which is a key factor to gauge global warming and gain a better understanding of the mechanisms behind rising mean sea level. High precision and quality of these global ocean climate indicators are necessary to observe the ocean's role in the Earth's climate system. Data from the global Argo array, from satellite altimetry (AVISO) and satellite derived ocean mass (GRACE) are used here during the period January 2005 to December 2010 to assess the quality of Argo climate indicators. The up-dated Argo Global Ocean Indicators (GOIs) for the period 2005.0-2011.0 reveal a 7-year rate of 0.5±0.1 W/m2 (1-standard error) for global ocean heat content (GOHC) and 0.4±0.2 mm/year for global steric sea level (GSSL). Although we can close the global sea level budget within the uncertainty intervals during the years 2005-2010 a significant positive trend of the residual is observed relative to the residual variance - even when we reduce Argo sampling issues. This must be due to systematic biases in or more of the observations with a smaller portion possibly coming from thermosteric changes below 1500m depth. We could identify and reduce with our method a systematic bias introduced by lower Argo sampling in some parts of the tropical ocean sector, in particular in the Indonesian Archipalo region. Uncertainties of the global observing systems are still too large to allows us to 'open a window' enabling to infer deep ocean warming changes from the global sea level budget. The role of salinity changes for global and regional sea level changes, as well as their contribution to the global sea level budget is also assessed.

  4. Community Observatories: Fostering Ideas that STEM From Ocean Sense: Local Observations. Global Connections.

    NASA Astrophysics Data System (ADS)

    Pelz, M. S.; Ewing, N.; Hoeberechts, M.; Riddell, D. J.; McLean, M. A.; Brown, J. C. K.

    2015-12-01

    Ocean Networks Canada (ONC) uses education and communication to inspire, engage and educate via innovative "meet them where they are, and take them where they need to go" programs. ONC data are accessible via the internet allowing for the promotion of programs wherever the learners are located. We use technologies such as web portals, mobile apps and citizen science to share ocean science data with many different audiences. Here we focus specifically on one of ONC's most innovative programs: community observatories and the accompanying Ocean Sense program. The approach is based on equipping communities with the same technology enabled on ONC's large cabled observatories. ONC operates the world-leading NEPTUNE and VENUS cabled ocean observatories and they collect data on physical, chemical, biological, and geological aspects of the ocean over long time periods, supporting research on complex Earth processes in ways not previously possible. Community observatories allow for similar monitoring on a smaller scale, and support STEM efforts via a teacher-led program: Ocean Sense. This program, based on local observations and global connections improves data-rich teaching and learning via visualization tools, interactive plotting interfaces and lesson plans for teachers that focus on student inquiry and exploration. For example, students use all aspects of STEM by accessing, selecting, and interpreting data in multiple dimensions, from their local community observatories to the larger VENUS and NEPTUNE networks. The students make local observations and global connections in all STEM areas. The first year of the program with teachers and students who use this innovative technology is described. Future community observatories and their technological applications in education, communication and STEM efforts are also described.

  5. An analysis of young ocean depth, gravity and global residual topography

    NASA Astrophysics Data System (ADS)

    Crosby, A. G.; McKenzie, D.

    2009-09-01

    The variation of ocean depth with age in the absence of crustal thickening and dynamic support places valuable constraints on the thermal and rheological properties of the lithosphere and asthenosphere. We have attempted to estimate this variation using a global data set of shiptracks, with particular emphasis on young ocean floor. In this respect, this paper extends a previous study published in this journal by the same authors, which concentrated on the older parts of the ocean basins. We find that, prior to 80 Ma, subsidence patterns are reasonably consistent, with gradients of 325 +/- 20 m Ma -1/2 and zero-age depths of 2600 +/- 200 m. There is a strong inverse correlation between zero-age depth and the gradient of depth with the square root of age which is unrelated to local variations in dynamic support. Global depth-age trends to 160 Ma are not significantly different to those for the individual ocean basins. Within corridors of similar basement age, gravity-topography correlations are consistently 30 +/- 5 mGal km-1. Simple isostatic theory and numerical modelling of mantle plumes suggests that, if the minimum depth of convection is defined by the base of the mechanical boundary layer, the admittance should be a function of plate age. The observation that it is not implies that the active convective upwelling beneath young lithosphere ceases at the same depth as it does beneath old oceanic plates. This result is consistent with geochemical modelling of melts near mid-ocean ridges. We have examined the relationship between residual topography and gravity worldwide, and have found that good spatial correlations are restricted to the Atlantic, North Pacific and youngest Indian ocean basins. By contrast, residual topography and gravity are poorly or negatively correlated in the South and young North Pacific Ocean and in the older Indian Ocean. Away from regions of thick crust and flexure, histograms of residual topography and gravity have symmetric

  6. Assessing the Impact of Data Assimilation on Acoustic Predictions in Operational Global Ocean Models

    NASA Astrophysics Data System (ADS)

    Barron, C. N.; Townsend, T. L.; Smedstad, L. F.; Helber, R. W.; Dastugue, J. M.

    2009-04-01

    Since accurate representation of sound speed is a major objective for operational naval ocean models, metrics focusing on acoustically relevant properties are used to evaluate potential changes to the systems. In particular, planned upgrades to the U.S. navy's operational Global Ocean Forecast System (GOFS) addressed aspects of the water column significant for predictions of acoustic propagation: mixed-layer depth (MLD), sonic-layer depth (SLD), and below-layer gradient. These properties were only indirectly considered in prior approaches focused on minimizing expected errors in temperature and salinity. The latest global capability, GOFS 2.6, introduces use of MLD-modified synthetic profiles based on vertical projection of satellite sea surface height and temperature as a background for Navy Coupled Ocean Data Assimilation (NCODA) analyses of in-situ data. Evaluation relative to unassimilated in situ observations reveals the continuing progress of successive operational systems. Because of these demonstrated improvements over prior capabilities, forecasts from the Navy Coastal Ocean Model in GOFS 2.6 and higher resolution regional NCOM implementations were announced as the new standard for U.S. Navy Operational Sound Speed Prediction (NOSSP) on 21 Aug. 2008.

  7. A global ocean inventory of anthropogenic mercury based on water column measurements.

    PubMed

    Lamborg, Carl H; Hammerschmidt, Chad R; Bowman, Katlin L; Swarr, Gretchen J; Munson, Kathleen M; Ohnemus, Daniel C; Lam, Phoebe J; Heimbürger, Lars-Eric; Rijkenberg, Micha J A; Saito, Mak A

    2014-08-01

    Mercury is a toxic, bioaccumulating trace metal whose emissions to the environment have increased significantly as a result of anthropogenic activities such as mining and fossil fuel combustion. Several recent models have estimated that these emissions have increased the oceanic mercury inventory by 36-1,313 million moles since the 1500s. Such predictions have remained largely untested owing to a lack of appropriate historical data and natural archives. Here we report oceanographic measurements of total dissolved mercury and related parameters from several recent expeditions to the Atlantic, Pacific, Southern and Arctic oceans. We find that deep North Atlantic waters and most intermediate waters are anomalously enriched in mercury relative to the deep waters of the South Atlantic, Southern and Pacific oceans, probably as a result of the incorporation of anthropogenic mercury. We estimate the total amount of anthropogenic mercury present in the global ocean to be 290 ± 80 million moles, with almost two-thirds residing in water shallower than a thousand metres. Our findings suggest that anthropogenic perturbations to the global mercury cycle have led to an approximately 150 per cent increase in the amount of mercury in thermocline waters and have tripled the mercury content of surface waters compared to pre-anthropogenic conditions. This information may aid our understanding of the processes and the depths at which inorganic mercury species are converted into toxic methyl mercury and subsequently bioaccumulated in marine food webs. PMID:25100482

  8. The role of mesoscale tracer transports in the global ocean circulation

    SciTech Connect

    Danabasoglu, G.; McWilliams, J.C.; Gent, P.R.

    1994-05-20

    Ocean models routinely used in simulations of the Earth`s climate do not resolve mesoscale eddies because of the immense computational cost. A new parameterization of the effects of these eddies has been implemented in a widely used model. A comparison of its solution with that of the conventional parameterization shows significant improvements in the global temperature distribution, the poleward and surface heat fluxes, and the locations of deep-water formation.

  9. Global net community production and the putative net heterotrophy of the oligotrophic oceans

    NASA Astrophysics Data System (ADS)

    Westberry, Toby K.; Williams, Peter J. Le B.; Behrenfeld, Michael J.

    2012-12-01

    Reconciling rates of organic carbon export from the euphotic zone with the consumption of organic material in the dark ocean remains one of the major quantitative uncertainties of the ocean carbon cycle. Euphotic zone net community production (NCP) provides one broad constraint on export flux and potential carbon drawdown. However, in vitro measurements of NCP consistently suggest that oligotrophic oceans are net heterotrophic, which is inconsistent with evidence of their carbon export to depth. Further, we have been unable to identify organic inputs on a scale to supplement the purported net heterotrophy. Here, we calculate global NCP rates using empirical relationships between in vitro photosynthesis (P) and respiration (R) and a satellite-based productivity model. A low value for global NCP (˜139 ± 325 Tmol C a-1) is found when a single P versus R (PvR) relation is derived from all in vitro data, with areas of net heterotrophy occupying 52% of the surface ocean. If a set of PvR relationships are instead derived by segregating the in vitro data into broad latitudinal zones associated with differing nutrient dynamics, we find a global NCP distribution in better agreement with independent model estimates of particulate carbon export, except in the 10°-40° latitudinal band where negative NCP values remain. Consistency between NCP and particulate export across all latitudes is achieved by applying a single PvR relationship derived using all in vitro data collected outside the 10°-40° latitudinal band. With this model, global NCP is estimated at ˜781 ± 393 Tmol C a-1 and modeled values at well-characterized field sites are in good agreement with non-incubation based in situ measurements. We infer from our results that in vitro NCP data from oligotrophic sites are too low, and suggest that this error is more likely the result of underestimated photosynthesis than overestimated respiration, although the precise physiological nature of the problem remains to be

  10. Transports and budgets of volume, heat, and salt from a global eddy-resolving ocean model

    SciTech Connect

    McCann, M.P.; Semtner, A.J. Jr.; Chervin, R.M.

    1994-07-01

    The results from an integration of a global ocean circulation model have been condensed into an analysis of the volume, heat, and salt transports among the major ocean basins. Transports are also broken down between the model`s Ekman, thermocline, and deep layers. Overall, the model does well. Horizontal exchanges of mass, heat, and salt between ocean basins have reasonable values: and the volume of North Atlantic Deep Water (NADW) transport is in general agreement with what limited observations exist. On a global basis the zonally integrated meridional heat transport is poleward at all latitudes except for the latitude band 30{degrees}S to 45{degrees}S. This anomalous transport is most likely a signature of the model`s inability to form Antarctic Intermediate (AAIW) and Antarctic bottom water (AABW) properly. Eddy heat transport is strong at the equator where its convergence heats the equatorial Pacific about twice as much as it heats the equatorial Atlantic. The greater heating in the Pacific suggests that mesoscale eddies may be a vital mechanism for warming and maintaining an upwelling portion of the global conveyor-belt circulation. The model`s fresh water transport compares well with observations. However, in the Atlantic there is an excessive southward transport of fresh water due to the absence of the Mediterranean outflow and weak northward flow of AAIW. Perhaps the model`s greatest weakness is the lack of strong AAIW and AABW circulation cells. Accurate thermohaline forcing in the North Atlantic (based on numerous hydrographic observations) helps the model adequately produce NADW. In contrast, the southern ocean is an area of sparse observation. Better thermohaline observations in this area may be needed if models such as this are to produce the deep convection that will achieve more accurate simulations of the global 3-dimensional circulation. 41 refs., 18 figs., 1 tab.

  11. NAVSTAR global positioning system applicability to the National Oceanic Satellite System

    NASA Technical Reports Server (NTRS)

    Matchett, G. A.

    1980-01-01

    This report presents the results of a preliminary investigation into the potential for applying NAVSTAR Global Positioning System (GPS) user equipment to the spacecraft of the National Oceanic Satellite System (NOSS). Two widely different navigation goals for NOSS spacecraft are examined: one being moderate accuracy, real-time navigation utilizing the simplest of GPS receivers, and the other being precision vertical displacement measurement over limited arcs utilizing specialized GPS equipment, possibly with ground data processing.

  12. The coastal ocean response to the global warming acceleration and hiatus

    PubMed Central

    Liao, Enhui; Lu, Wenfang; Yan, Xiao-Hai; Jiang, Yuwu; Kidwell, Autumn

    2015-01-01

    Coastlines are fundamental to humans for habitation, commerce, and natural resources. Many coastal ecosystem disasters, caused by extreme sea surface temperature (SST), were reported when the global climate shifted from global warming to global surface warming hiatus after 1998. The task of understanding the coastal SST variations within the global context is an urgent matter. Our study on the global coastal SST from 1982 to 2013 revealed a significant cooling trend in the low and mid latitudes (31.4% of the global coastlines) after 1998, while 17.9% of the global coastlines changed from a cooling trend to a warming trend concurrently. The trend reversals in the Northern Pacific and Atlantic coincided with the phase shift of Pacific Decadal Oscillation and North Atlantic Oscillation, respectively. These coastal SST changes are larger than the changes of the global mean and open ocean, resulting in a fast increase of extremely hot/cold days, and thus extremely hot/cold events. Meanwhile, a continuous increase of SST was detected for a considerable portion of coastlines (46.7%) with a strengthened warming along the coastlines in the high northern latitudes. This suggests the warming still continued and strengthened in some regions after 1998, but with a weaker pattern in the low and mid latitudes. PMID:26568024

  13. The coastal ocean response to the global warming acceleration and hiatus

    NASA Astrophysics Data System (ADS)

    Liao, Enhui; Lu, Wenfang; Yan, Xiao-Hai; Jiang, Yuwu; Kidwell, Autumn

    2015-11-01

    Coastlines are fundamental to humans for habitation, commerce, and natural resources. Many coastal ecosystem disasters, caused by extreme sea surface temperature (SST), were reported when the global climate shifted from global warming to global surface warming hiatus after 1998. The task of understanding the coastal SST variations within the global context is an urgent matter. Our study on the global coastal SST from 1982 to 2013 revealed a significant cooling trend in the low and mid latitudes (31.4% of the global coastlines) after 1998, while 17.9% of the global coastlines changed from a cooling trend to a warming trend concurrently. The trend reversals in the Northern Pacific and Atlantic coincided with the phase shift of Pacific Decadal Oscillation and North Atlantic Oscillation, respectively. These coastal SST changes are larger than the changes of the global mean and open ocean, resulting in a fast increase of extremely hot/cold days, and thus extremely hot/cold events. Meanwhile, a continuous increase of SST was detected for a considerable portion of coastlines (46.7%) with a strengthened warming along the coastlines in the high northern latitudes. This suggests the warming still continued and strengthened in some regions after 1998, but with a weaker pattern in the low and mid latitudes.

  14. Response of the tropical Pacific Ocean to El Niño versus global warming

    NASA Astrophysics Data System (ADS)

    Liu, Fukai; Luo, Yiyong; Lu, Jian; Wan, Xiuquan

    2016-04-01

    Climate models project an El Niño-like SST response in the tropical Pacific Ocean to global warming (GW). By employing the Community Earth System Model and applying an overriding technique to its ocean component, Parallel Ocean Program version 2, this study investigates the similarity and difference of formation mechanism for the changes in the tropical Pacific Ocean under El Niño and GW. Results show that, despite sharing some similarities between the two scenarios, there are many significant distinctions between GW and El Niño: (1) the phase locking of the seasonal cycle reduction is more notable under GW compared with El Niño, implying more extreme El Niño events in the future; (2) in contrast to the penetration of the equatorial subsurface temperature anomaly that appears to propagate in the form of an oceanic equatorial upwelling Kelvin wave during El Niño, the GW-induced subsurface temperature anomaly manifest in the form of off-equatorial upwelling Rossby waves; (3) while significant across-equator northward heat transport (NHT) is induced by the wind stress anomalies associated with El Niño, little NHT is found at the equator due to a symmetric change in the shallow meridional overturning circulation that appears to be weakened in both North and South Pacific under GW; and (4) heat budget analysis shows that the maintaining mechanisms for the eastern equatorial Pacific warming are also substantially different.

  15. Comparison and validation of global and regional ocean forecasting systems for the South China Sea

    NASA Astrophysics Data System (ADS)

    Zhu, Xueming; Wang, Hui; Liu, Guimei; Régnier, Charly; Kuang, Xiaodi; Wang, Dakui; Ren, Shihe; Jing, Zhiyou; Drévillon, Marie

    2016-07-01

    In this paper, the performance of two operational ocean forecasting systems, the global Mercator Océan (MO) Operational System, developed and maintained by Mercator Océan in France, and the regional South China Sea Operational Forecasting System (SCSOFS), by the National Marine Environmental Forecasting Center (NMEFC) in China, have been examined. Both systems can provide science-based nowcast/forecast products of temperature, salinity, water level, and ocean circulations. Comparison and validation of the ocean circulations, the structures of temperature and salinity, and some mesoscale activities, such as ocean fronts, typhoons, and mesoscale eddies, are conducted based on observed satellite and in situ data obtained in 2012 in the South China Sea. The results showed that MO performs better in simulating the ocean circulations and sea surface temperature (SST), and SCSOFS performs better in simulating the structures of temperature and salinity. For the mesoscale activities, the performance of SCSOFS is better than MO in simulating SST fronts and SST decrease during Typhoon Tembin compared with the previous studies and satellite data; but model results from both of SCSOFS and MO show some differences from satellite observations. In conclusion, some recommendations have been proposed for both forecast systems to improve their forecasting performance in the near future based on our comparison and validation.

  16. The global pattern of trace-element distributions in ocean floor basalts.

    PubMed

    O'Neill, Hugh St C; Jenner, Frances E

    2012-11-29

    The magmatic layers of the oceanic crust are created at constructive plate margins by partial melting of the mantle as it wells up. The chemistry of ocean floor basalts, the most accessible product of this magmatism, is studied for the insights it yields into the compositional heterogeneity of the mantle and its thermal structure. However, before eruption, parental magma compositions are modified at crustal pressures by a process that has usually been assumed to be fractional crystallization. Here we show that the global distributions of trace elements in ocean floor basalts describe a systematic pattern that cannot be explained by simple fractional crystallization alone, but is due to cycling of magma through the global ensemble of magma chambers. Variability in both major and incompatible trace-element contents about the average global pattern is due to fluctuations in the magma fluxes into and out of the chambers, and their depth, as well as to differences in the composition of the parental magmas. PMID:23192147

  17. Complex response of dinoflagellate distribution patterns to cooler early Oligocene global oceans

    NASA Astrophysics Data System (ADS)

    Woods, Mark; Vandenbroucke, Thijs; Williams, Mark; Riding, James; De Schepper, Stijn; Sabbe, Koen

    2013-04-01

    Analysis of dinoflagellate cysts using two new global ocean datasets for the Mid Eocene (Bartonian) and Early Oligocene (Rupelian) reveals unexpected changes in their global distribution. The impact of Rupelian cooling appears to be globally asymmetric; the dinoflagellate cyst cooling signal is clearer in the southern hemisphere, but much less evident in the northern hemisphere. Additionally, a significant number of species with low and mid-latitude northern hemisphere occurrences in the Bartonian, unexpectedly extend their northward ranges in the Rupelian, including some 'warm water' forms. This may show that Rupelian dinoflagellate cyst distribution is a response to changes in a range of environmental variables linked to climate-cooling, for example changes in nutrient fluxes triggered by glacially-induced base-level fall, or complex reorganisation of ocean current systems between the Bartonian and Rupelian. Apparent lack of a clear climate-cooling signal in Rupelian dinoflagellate cyst distribution may in part reflect published evidence suggesting that summer SSTs in the early Rupelian northern hemisphere were only slightly reduced compared to the later part of the Eocene, despite much colder winters. The relatively broad temperature tolerance of many extant dinoflagellate species, and dormant cyst formation during short-lived environmental deterioration, may have contributed to allowing Rupelian dinoflagellates to thrive in more highly seasonal but otherwise hospitable, northern hemisphere oceans.

  18. Modeling Abrupt Change in Global Sea Level Arising from Ocean - Ice-Sheet Interaction

    SciTech Connect

    Holland, David M

    2011-09-24

    It is proposed to develop, validate, and apply a coupled ocean ice-sheet model to simulate possible, abrupt future change in global sea level. This research is to be carried out collaboratively between an academic institute and a Department of Energy Laboratory (DOE), namely, the PI and a graduate student at New York University (NYU) and climate model researchers at the Los Alamos National Laboratory (LANL). The NYU contribution is mainly in the area of incorporating new physical processes into the model, while the LANL efforts are focused on improved numerics and overall model development. NYU and LANL will work together on applying the model to a variety of modeling scenarios of recent past and possible near-future abrupt change to the configuration of the periphery of the major ice sheets. The project's ultimate goal is to provide a robust, accurate prediction of future global sea level change, a feat that no fully-coupled climate model is currently capable of producing. This proposal seeks to advance that ultimate goal by developing, validating, and applying a regional model that can simulate the detailed processes involved in sea-level change due to ocean ice-sheet interaction. Directly modeling ocean ice-sheet processes in a fully-coupled global climate model is not a feasible activity at present given the near-complete absence of development of any such causal mechanism in these models to date.

  19. A modified algorithm for estimating Absolute Salinity in the global ocean

    NASA Astrophysics Data System (ADS)

    Uchida, H.; Kawano, T.; Aoyama, M.; Wakita, M.; Nishino, S.; Ozawa, S.

    2012-04-01

    In 2010, the Intergovernmental Oceanographic Commission (IOC), International Association for the Physical Sciences of the Ocean (IAPSO) and the Scientific Committee on Oceanic Research (SCOR) adopted the new Thermodynamic Equation of Seawater - 2010 (TEOS-10). One of the substantial changes from previous practice is the use of Absolute Salinity (g/kg) instead of Practical Salinity in TEOS-10. Since there is no sensor that can precisely measure Absolute Salinity in situ, an algorithm to estimate Absolute Salinity was provided along with TEOS-10. The algorithm exploits the correlation between the Absolute Salinity anomaly (dSA) relative to the Reference-Composition Salinity and the silicate concentration, making use of the global atlas of silicate concentrations, and the correlation coefficient is a function of latitude determined for each ocean basin (McDougall et al., Ocean Sci. Discuss., 6, 215-242, 2009). However, the dSA shows latitude dependent systematic discrepancy from dSA estimated from another model which exploits more precisely the correlation between dSA and nutrient concentrations and carbonate system parameters based on mathematical investigation (Pawlowicz et al., Ocean Sci., 7, 363-387, 2011). These two models for estimating dSA were evaluated using measured dSA with an oscillation-type density meter for the North Pacific, the Bering Sea, and the Arctic Ocean. The measured dSA agreed well with the estimates of the multi-parameter model. These results suggest that the algorithm for estimating dSA used in TEOS-10 have latitude dependent systematic biases (~0.01 g/kg), probably due to systematic biases in density data used. To minimize these systematic biases, a simple relationship between dSA and silicate concentration was determined for the global ocean, regardless of latitude dependency, by combining previously used and newly obtained density data. For the surface water of the Arctic Ocean, however, dSA is related with alkalinity by the input of

  20. Changes in Global Ocean Bottom Properties and Volume Transports in CMIP5 Models under Climate Change Scenarios

    NASA Astrophysics Data System (ADS)

    Heuzé, C.; Heywood, K. J.; Stevens, D. P.; Ridley, J. K.

    2014-12-01

    Changes in bottom temperature, salinity and density in the global ocean by 2100 for 24 CMIP5 climate models are investigated for the climate change scenarios RCP4.5 and RCP8.5. The multimodel mean shows a decrease in density in all deep basins except for the North Atlantic which becomes denser. The individual model responses to climate change forcing are more complex: regarding temperature, only one model predicts a cooling of the bottom waters while the 23 others predict a warming; in salinity, there is less agreement regarding the sign of the change, especially in the Southern Ocean. The magnitude and equatorward extent of these changes also vary strongly among models. The changes in properties can be linked with the changes in transport of key water masses. The Atlantic Meridional Overturning Circulation weakens in most models and is directly linked to changes in bottom density in the North Atlantic. These changes are due to the intrusion of modified Antarctic Bottom Water, made possible by the decrease in North Atlantic Deep Water formation. In the Indian, Pacific and South Atlantic basins, changes in bottom density are congruent with the weakening in Antarctic Bottom Water transport through these basins. We argue that the greater the meridional transport, the more the change is propagated towards the equator. Then strong decreases in density over 100 years of climate change cause a weakening of the transports. The speed at which these property changes reach the deep basins is critical for a correct assessment of the heat storage capacity of the oceans as well as for predictions of future sea level rise.

  1. Improving the parameters of a global ocean biogeochemical model via variational assimilation of in situ data at five time series stations

    NASA Astrophysics Data System (ADS)

    Kane, A.; Moulin, C.; Thiria, S.; Bopp, L.; Berrada, M.; Tagliabue, A.; CréPon, M.; Aumont, O.; Badran, F.

    2011-06-01

    The global ocean biogeochemical models that are used in order to assess the ocean role in the global carbon cycle and estimate the impact of the climate change on marine ecosystems are getting more and more sophisticated. They now often account for several phytoplankton functional types that play particular roles in marine food webs and the ocean carbon cycle. These phytoplankton functional types have specific physiological characteristics, which are usually poorly known and therefore add uncertainties to model results. Indeed, this evolution in model complexity is not accompanied by a similar increase in the number and diversity of in situ data sets necessary for model calibration and evaluation. Thus, it is of primary importance to develop new methods to improve model performance using existing biogeochemical data sets, despite their current limitations. In this paper, we have optimized 45 physiological parameters of the PISCES global model, using a variational optimal control method. In order to bypass a global 3-D ocean variational assimilation, which would require enormous computation and memory storage, we have simplified the estimation procedure by assimilating monthly climatological in situ observations at five contrasted oceanographic stations of the JGOFS program in a 1-D version of the PISCES model. We began by estimating the weight matrix in the cost function by using heuristic considerations. Then we used this matrix to estimate the 45 parameters of the 1-D version of the PISCES model by assimilating the different monthly profiles (observed profiles at the five stations) in the same variational procedure on a time window of 1 year. This set of optimized parameters was then used in the standard 3-D global PISCES version to perform a 500 year global simulation. The results of both the standard and the optimized versions of the model were compared to satellite-derived chlorophyll-a images, which are an independent and global data set, showing that our

  2. Storage of Heat in the Glacial Deep Ocean and the Importance of Seawater Thermodynamics in Climate Change

    NASA Astrophysics Data System (ADS)

    Adkins, J. F.; Pasquero, C.

    2004-12-01

    A variety of records of both oceanic and atmospheric variability link Dansgaard/Oeschger events and Bond Cycles to changes in the overturning strength of the deep ocean. Various models have shown that the observed temperature changes and circulation switches can be forced with variations in the freshwater budget of the North Atlantic surface ocean. However, recent evidence from sediment pore fluids show that the stratification of LGM deep waters was dominated by salinity, rather than temperature. If the saltiest waters of the glacial deep ocean were produced in the Southern Ocean, than salinification of surface waters in the North Atlantic cannot produce large transients in overturning strength without some other source of buoyancy to erode the deep stratification. Here we present an energy storage mechanism, thermobaricity, and an energy source, geothermal heating, that implicate the deep ocean as the origin of the glacial rapid climate changes and the source of this buoyancy. Salinity stratification of the deep ocean during the glacial can lead to heat storage in the abyss that will decrease the deep to surface density difference and then, due to the non-linearity of the seawater equation of state, could periodically cause catastrophic convective events. This "thermobaric convection" arises from the pressure dependence of the seawater thermal expansion coefficient. Our contention is that the thermodynamics of seawater could play an important a role in glacial ocean/atmosphere reorganizations. We will outline how the pressure dependence of the seawater thermal expansion coefficient can lead to occasional rapid overturning of the deep ocean and present some new model results that examine the feasibility of this idea.

  3. Global garbage collection for distributed heap storage systems

    SciTech Connect

    Ali, K.A.M.; Haridi, S.

    1986-10-01

    The authors present a garbage-collection algorithm, suitable for loosely-coupled multi-processor systems, in which the processing elements (PEs) share only the communication medium. The algorithm is global, i.e., it involves all the PEs in the system. It allows space compaction, and it uses a system-wide marking phase to mark all accessible objects where a combination of parallel breadth-first/depth-first strategies is used for tracing the object-graphs according to a decentralized credit mechanism that regulates the number of garbage collections messages in the system. The credit mechanism is crucial for determining the space requirement of the garbage-collection messages. Also a variation of this algorithm is presented for systems with high locality of reference. It allows each PE to perform first its local garbage collection and only invokes the global garbage collection when the freed space by the local collector is insufficient.

  4. A Global Census of Marine Life on Seamounts: are They Really Oases in the Ocean?

    NASA Astrophysics Data System (ADS)

    Consalvey, M.; Clark, M.; Rowden, A.; Stocks, K.

    2006-12-01

    Seamounts have been referred to as oases in the ocean, yet our knowledge is such that this notion can neither be refuted nor accepted. We know that seamounts can support high levels of biodiversity and endemism, that they can play an important role in patterns of marine biogeography, and that they can be highly productive ecosystems acting as feeding grounds for fishes, marine mammals and seabirds. However, our current state of knowledge is such that these observations cannot be taken as generalisations. Under the umbrella of the Census of Marine Life the project CenSeam is conducting a global census of marine life on seamounts, and working towards quantifying what is known, unknown, and will never be known. Seamounts are found in every ocean of the world but of the estimated 100 000, less than 400 have been sampled, and of these, less than 100 in sufficient biological detail. Furthermore, the global sampling effort has been geographically biased - high latitude as well as equatorial seamounts are currently under sampled and the majority of sampled seamounts have summit depths of less than 500m, sampling being limited by practical and financial capabilities. Through uniting the active seamount research community CenSeam aims to establish, at a global scale, the roles that seamounts play in the biogeography, biodiversity, productivity and evolution of marine organisms in order to determine the effect and contribution of seamounts to the global oceanic ecosystem. Recognising that it is not feasible to sample all the world's seamounts, future sampling efforts must be standardised and strategically guided, through assessing the current state of knowledge, to fill critical knowledge gaps and target understudied regions and types of seamounts. This paper will synthesise the current state of seamount knowledge and critically evaluate the global sampling effort stimulating discussion about the future of seamount research and associated methodology and data analysis.

  5. Declining global per capita agricultural production and warming oceans threaten food security

    USGS Publications Warehouse

    Funk, Christopher C.; Brown, Molly E.

    2009-01-01

    Despite accelerating globalization, most people still eat food that is grown locally. Developing countries with weak purchasing power tend to import as little food as possible from global markets, suffering consumption deficits during times of high prices or production declines. Local agricultural production, therefore, is critical to both food security and economic development among the rural poor. The level of local agricultural production, in turn, will be determined by the amount and quality of arable land, the amount and quality of agricultural inputs (fertilizer, seeds, pesticides, etc.), as well as farm-related technology, practices and policies. This paper discusses several emerging threats to global and regional food security, including declining yield gains that are failing to keep up with population increases, and warming in the tropical Indian Ocean and its impact on rainfall. If yields continue to grow more slowly than per capita harvested area, parts of Africa, Asia and Central and Southern America will experience substantial declines in per capita cereal production. Global per capita cereal production will potentially decline by 14% between 2008 and 2030. Climate change is likely to further affect food production, particularly in regions that have very low yields due to lack of technology. Drought, caused by anthropogenic warming in the Indian and Pacific Oceans, may also reduce 21st century food availability in some countries by disrupting moisture transports and bringing down dry air over crop growing areas. The impacts of these circulation changes over Asia remain uncertain. For Africa, however, Indian Ocean warming appears to have already reduced rainfall during the main growing season along the eastern edge of tropical Africa, from southern Somalia to northern parts of the Republic of South Africa. Through a combination of quantitative modeling of food balances and an examination of climate change, this study presents an analysis of emerging

  6. Sensitivity of simulated global-scale freshwater fluxes and storages to input data, hydrological model structure, human water use and calibration

    NASA Astrophysics Data System (ADS)

    Müller Schmied, H.; Eisner, S.; Franz, D.; Wattenbach, M.; Portmann, F. T.; Flörke, M.; Döll, P.

    2014-09-01

    Global-scale assessments of freshwater fluxes and storages by hydrological models under historic climate conditions are subject to a variety of uncertainties. Using the global hydrological model WaterGAP (Water - Global Assessment and Prognosis) 2.2, we investigated the sensitivity of simulated freshwater fluxes and water storage variations to five major sources of uncertainty: climate forcing, land cover input, model structure/refinements, consideration of human water use and calibration (or no calibration) against observed mean river discharge. In a modeling experiment, five variants of the standard version of WaterGAP 2.2 were generated that differed from the standard version only regarding the investigated source of uncertainty. The basin-specific calibration approach for WaterGAP was found to have the largest effect on grid cell fluxes as well as on global AET (actual evapotranspiration) and discharge into oceans for the period 1971-2000. Regarding grid cell fluxes, climate forcing ranks second before land cover input. Global water storage trends are most sensitive to model refinements (mainly modeling of groundwater depletion) and consideration of human water use. The best fit to observed time series of monthly river discharge or discharge seasonality is obtained with the standard WaterGAP 2.2 model version which is calibrated and driven by daily reanalysis-based WFD/WFDEI (combination of Watch Forcing Data based on ERA40 and Watch Forcing Data based on ERA-Interim) climate data. Discharge computed by a calibrated model version using monthly CRU TS (Climate Research Unit time-series) 3.2 and GPCC (Global Precipitation Climatology Center) v6 climate input reduced the fit to observed discharge for most stations. Taking into account uncertainties of climate and land cover data, global 1971-2000 discharge into oceans and inland sinks ranges between 40 000 and 42 000 km3 yr-1. Global actual evapotranspiration, with 70 000 km3 yr-1, is rather unaffected by climate

  7. Ectomycorrhizal fungi increase soil carbon storage: molecular signatures of mycorrhizal competition driving soil C storage at global scale

    NASA Astrophysics Data System (ADS)

    Averill, C.; Barry, B. K.; Hawkes, C.

    2015-12-01

    Soil carbon storage and decay is regulated by the activity of free-living decomposer microbes, which can be limited by nitrogen availability. Many plants associate with symbiotic ectomycorrhizal fungi on their roots, which produce nitrogen-degrading enzymes and may be able to compete with free-living decomposers for soil organic nitrogen. By doing so, ectomycorrhizal fungi may able to induce nitrogen limitation and reduce activity of free-living microbial decomposition by mining soil organic nitrogen. The implication is that ectomycorrhizal-dominated systems should have increased soil carbon storage relative to non-ectomycorrhizal systems, which has been confirmed at a global scale. To investigate these effects, we analyzed 364 globally distributed observations of soil fungal communities using 454 sequencing of the ITS region, along with soil C and N concentrations, climate and chemical data. We assigned operational taxonomic units using the QIIME pipeline and UNITE fungal database and assigned fungal reads as ectomycorrhizal or non-mycorrhizal based on current taxonomic knowledge. We tested for associations between ectomycorrhizal abundance, climate, and soil carbon and nitrogen. Sites with greater soil carbon had quantitatively more ectomycorrhizal fungi within the soil microbial community based on fungal sequence abundance, after accounting for soil nitrogen availability. This is consistent with our hypothesis that ectomycorrhizal fungi induce nitrogen-limitation of free-living decomposers and thereby increase soil carbon storage. The strength of the mycorrhizal effect increased non-linearly with ectomycorrhizal abundance: the greater the abundance, the greater the effect size. Mean annual temperature, potential evapotranspiration, soil moisture and soil pH were also significant predictors in the final AIC selected model. This analysis suggests that molecular data on soil microbial communities can be used to make quantitative biogeochemical predictions. The

  8. Global Autocorrelation Scales of the Partial Pressure of Oceanic CO2

    NASA Technical Reports Server (NTRS)

    Li, Zhen; Adamec, David; Takahashi, Taro; Sutherland, Stewart C.

    2004-01-01

    A global database of approximately 1.7 million observations of the partial pressure of carbon dioxide in surface ocean waters (pCO2) collected between 1970 and 2003 is used to estimate its spatial autocorrelation structure. The patterns of the lag distance where the autocorrelation exceeds 0.8 is similar to patterns in the spatial distribution of the first baroclinic Rossby radius of deformation indicating that ocean circulation processes play a significant role in determining the spatial variability of pCO2. For example, the global maximum of the distance at which autocorrelations exceed 0.8 averages about 140 km in the equatorial Pacific. Also, the lag distance at which the autocorrelation exceed 0.8 is greater in the vicinity of the Gulf Stream than it is near the Kuroshio, approximately 50 km near the Gulf Stream as opposed to 20 km near the Kuroshio. Separate calculations for times when the sun is north and south of the equator revealed no obvious seasonal dependence of the spatial autocorrelation scales. The pCO2 measurements at Ocean Weather Station (OWS) 'P', in the eastern subarctic Pacific (50 N, 145 W) is the only fixed location where an uninterrupted time series of sufficient length exists to calculate a meaningful temporal autocorrelation function for lags greater than a few days. The estimated temporal autocorrelation function at OWS 'P', is highly variable. A spectral analysis of the longest four pCO2 time series indicates a high level of variability occurring over periods from the atmospheric synoptic to the maximum length of the time series, in this case 42 days. It is likely that a relative peak in variability with a period of 3-6 days is related to atmospheric synoptic period variability and ocean mixing events due to wind stirring. However, the short length of available time series makes identifying temporal relationships between pCO2 and atmospheric or ocean processes problematic.

  9. Global oceanic thermo-haline warming trend in an eddy-permitting reanalysis context

    NASA Astrophysics Data System (ADS)

    Bricaud, Clement; Garric, Gilles; Ferry, Nicolas; Parent, Laurent

    2014-05-01

    Mercator Ocean, the French ocean forecasting center (www.mercator-ocean.fr), has been developing several operational forecasting systems and reanalysis of the physical and biogeochemical 3D-Ocean. In the framework of the European MyOcean project (www.myocean.eu.org), Mercator has produced global eddy-permitting reanalysis over the altimetry years (1992-2012). They are driven by the ECMWF atmospheric re-analyses ERAinterim at the surface via the CORE bulk formulae without any relaxation. In order to better capture high frequency variability, the atmospheric forcing is sampled to 3H conjointly with a diurnal cycle applied to the downwelling shortwave radiative atmospheric forcing. Those global ¼° reanalysis are based on the NEMO OGCM platform with 75 vertical z-levels. NEMO sea-ice model LIM2 is used with EVP rheology. The assimilation method is a reduced order Kalman filter based on SEEK formulation with bias correction scheme for temperature and salinity and an Incremental Analysis Update. Data assimilated are in situ profiles (CORIOLIS GDAC), REYNOLDS 0.25° AVHRR-only SST, AVISO along track SLA, and Mean Dynamic Topography (CNES-CLS09). Distribution of the 3D thermo-haline content in different layers is evaluated in terms of linear trend and compared favorably to estimations issued from in-situ data base (ARGO network). The 2-dimensional trend of the steric signal, in general agreement with in-situ estimation, is particularly emphasized. A similar experiment performed without assimilation also allowed us to qualify the model and the assimilation components of the reanalysis system.

  10. Global Distribution of Aerosols Over the Open Ocean as Derived from the Coastal Zone Color Scanner

    NASA Technical Reports Server (NTRS)

    Stegmann, P. M.; Tindale, N. W.

    1999-01-01

    Climatological maps of monthly mean aerosol radiance levels derived from the coastal zone color scanner (CZCS) were constructed for the world's ocean basins. This is the first study to use the 7.5.-year CZCS data set to examine the distribution and seasonality of aerosols over the open ocean on a global scale. Examination of our satellite images found the most prominent large-scale patch of elevated aerosol radiances in each month off the coast of northwest Africa. The well-known, large-scale plumes of elevated aerosol levels in the Arabian Sea, the northwest Pacific, and off the east coast of North America were also successfully captured. Radiance data were extracted from 13 major open-ocean zones, ranging from the subpolar to equatorial regions. Results from these extractions revealed the aerosol load in both subpolar and subtropical zones to be higher in the Northern Hemisphere than in the Southern Hemisphere. Aerosol radiances in the subtropics of both hemispheres were about 2 times higher in summer than in winter. In subpolar regions, aerosol radiances in late spring/early summer were almost 3 times that observed in winter. In general, the aerosol signal was higher during the warmer months and lower during the cooler months, irrespective of location. A comparison between our mean monthly aerosol radiance maps with mean monthly chlorophyll maps (also from CZCS) showed similar seasonality between aerosol and chlorophyll levels in the subpolar zones of both hemispheres, i.e., high levels in summer, low levels in winter. In the subtropics of both hemispheres, however, chlorophyll levels were higher in winter months which coincided with a depressed aerosol signal. Our results indicate that the near-IR channel on ocean color sensors can be used to successfully capture well-known, large-scale aerosol plumes on a global scale and that future ocean color sensors may provide a platform for long-term synoptic studies of combined aerosol-phytoplankton productivity

  11. General Bathymetric Chart of the Oceans (GEBCO) - Mapping the Global Seafloor

    NASA Astrophysics Data System (ADS)

    Weatherall, P.; Jakobsson, M.; Marks, K. M.

    2014-12-01

    For over one hundred years GEBCO (www.gebco.net) has been at the forefront of producing maps and digital data sets showing the shape of the global seafloor in the deep oceans with the first GEBCO chart series initiated in 1903 by Prince Albert I of Monaco. Today the GEBCO community consists of an international group of experts in seafloor mapping who develop a range of data sets and data products with the aim of providing the most authoritative publicly-available bathymetric data sets for the world's oceans. We are also training a new generation of seafloor mappers through the Nippon Foundation/GEBCO Training Programme. GEBCO operates under the joint auspices of the Intergovernmental Oceanographic Commission (IOC) of UNESCO and the International Hydrographic Organization (IHO). Our range of products includes: A global Digital Terrain Model (DTM) - modelling the shape of the seafloor in the form of a periodically-updated 30 arc-second interval grid A gazetteer of undersea feature names GEBCO Cook Book - information on topics related to building bathymetric grids Web services GEBCO world map GEBCO Digital Atlas - a collection of GEBCO's data sets and viewing software Recognising the importance of local expertise when building a bathymetric grid, GEBCO's latest 30 arc-second interval DTM, GEBCO_2014, (due for release in Fall 2014) has benefited from contributions from many regional mapping projects such as the International Bathymetric Charts of the Arctic Ocean (IBCAO) and Southern Ocean (IBCSO); the Baltic Sea Bathymetry Database and EMODnet for European waters. Through the Sub-Committee on Regional Undersea Mapping, GEBCO is aiming to build on and extend its collaboration with regional mapping groups to continually improve its global bathymetric model.

  12. Monitoring and Predicting the Export and Fate of Global Ocean Net Primary Production: The EXPORTS Field Program

    NASA Astrophysics Data System (ADS)

    Exports Science Definition Team

    2016-04-01

    Ocean ecosystems play a critical role in the Earth's carbon cycle and its quantification on global scales remains one of the greatest challenges in global ocean biogeochemistry. The goal of the EXport Processes in the Ocean from Remote Sensing (EXPORTS) science plan is to develop a predictive understanding of the export and fate of global ocean primary production and its implications for the Earth's carbon cycle in present and future climates. NASA's satellite ocean-color data record has revolutionized our understanding of global marine systems. EXPORTS is designed to advance the utility of NASA ocean color assets to predict how changes in ocean primary production will impact the global carbon cycle. EXPORTS will create a predictive understanding of both the export of organic carbon from the euphotic zone and its fate in the underlying "twilight zone" (depths of 500 m or more) where variable fractions of exported organic carbon are respired back to CO2. Ultimately, it is the sequestration of deep organic carbon transport that defines the impact of ocean biota on atmospheric CO2 levels and hence climate. EXPORTS will generate a new, detailed understanding of ocean carbon transport processes and pathways linking upper ocean phytoplankton processes to the export and fate of organic matter in the underlying twilight zone using a combination of field campaigns, remote sensing and numerical modeling. The overarching objective for EXPORTS is to ensure the success of future satellite missions by establishing mechanistic relationships between remotely sensed signals and carbon cycle processes. Through a process-oriented approach, EXPORTS will foster new insights on ocean carbon cycling that will maximize its societal relevance and be a key component in the U.S. investment to understand Earth as an integrated system.

  13. Constraining the Extent and Intensity of Ocean De-oxygenation During Global Carbon Cycle Perturbations

    NASA Astrophysics Data System (ADS)

    Ridgwell, A. J.

    2014-12-01

    The extent and intensity of oxygen minimum zones have a first order relationship with the efficiency of nutrient and trace metal recycling in the oceans, global burial rates of organic carbon, and the availability of aerobe habitat. Reconstructing how the extent and intensity of oxygen depletion has varied with past changes in climate and global carbon cycle perturbation would enable something of the sensitivity of de-oxyenation (and its attendant impacts) to CO2 release to be quantified. However, even the extent of past de-oxygenation is notoriously difficult to constrain from the scattered and generally ocean margin and interior seaway dominated availability of observations. Spatially resolved global biogeochemical models can help, as by placing the distribution of records of any particular proxy into a global, mechanistic framework, one can make a more quantitative assessment of the observations. Moreover, multiple proxies with differing controls and sensitivities to redox state can be assessed simultaneously to help further constrain the interpretation. In this talk I will illustrate this (model-data) approach, taking examples from OAE2 and OAE1a, proxy records of seafloor anoxia and photic zone euxinia, and using the 'GENIE' Earth system model (http://mycgenie.seao2.org). I will also discuss what records and model-data approaches might be used to help better understand much subtler de-oxygenation events such as the PETM.

  14. Poseidon's paintbox : historical archives of ocean colour in global-change perspective

    NASA Astrophysics Data System (ADS)

    Wernand, M. R.

    2011-11-01

    In the thesis introduction issues are discussed on the historical background of marine optics and on marine optical devices that were used over the past centuries to observe and measure; as in all sciences, in marine optics we can see a steady development: that of ‘measuring’, beginning many centuries ago, to 'knowing' and since less than a century to the understanding of the phenomenon. Hereafter, six themes are treated successively. The first theme, ‘Ocean optics from 1600 (Hudson) to 1930 (Raman), shift in interpretation of natural water colouring’, addresses the question of why it took so long a time to explain the phenomenon ‘the colouring of the sea’, especially the blue colour, despite the age-long interest of sailors, for practical purposes of navigation and detection of fish - of which more later. The second theme ‘On the history of the Secchi disc’, describes the search to establish methods for the determination of (sea) water clarity concerning purposes of navigation (near coast colour changes) just mentioned to detect shoals, and for a more basic purpose, tracing lost objects. The search to determine the clarity of lakes and seas culminated in the invention of the Secchi disc, used since the late 19th century. The third theme, ‘Spectral analysis of the Forel-Ule ocean colour comparator scale’, addresses the accuracy of a colour scale proposed, used in limnology and oceanography. Scale observations are put into perspective with contemporary measurements on the colour of the sea. The fourth theme, ‘Ocean colour changes in the North Pacific since 1930’, handles the question whether long-term ocean colour changes using historic Forel-Ule observations, in this part of the ocean made very frequently over time, can be determined in relation to global change. In principal global warming may cause a gradual change in ocean colour due to the effect of biological, chemical and physical aspects of the ocean-surface. The fifth theme,

  15. Distribution of known macrozooplankton abundance and biomass in the global ocean

    NASA Astrophysics Data System (ADS)

    Moriarty, R.; Buitenhuis, E. T.; Le Quéré, C.; Gosselin, M.-P.

    2012-04-01

    Macrozooplankton are an important link between higher and lower trophic levels in the oceans. They serve as the primary food for fish, reptiles, birds and mammals in some regions, and play a role in the export of carbon from the surface to the intermediate and deep ocean. Little, however, is known of their global distribution and biomass. Here we compiled a dataset of macrozooplankton abundance and biomass observations for the global ocean from a collection of four datasets. We harmonise the data to common units, calculate additional carbon biomass where possible, and bin the dataset in a global 1 × 1 degree grid. This dataset is part of a wider effort to provide a global picture of carbon biomass data for key plankton functional types, in particular to support the development of marine ecosystem models. Over 387 700 abundance data and 1330 carbon biomass data have been collected from pre-existing datasets. A further 34 938 abundance data were converted to carbon biomass data using species-specific length frequencies or using species-specific abundance to carbon biomass data. Depth-integrated values are used to calculate known epipelagic macrozooplankton biomass concentrations and global biomass. Global macrozooplankton biomass has a mean of 8.4 μg C l-1, median of 0.15 μg C l-1 and a standard deviation of 63.46 μg C l-1. The global annual average estimate of epipelagic macrozooplankton, based on the median value, is 0.02 Pg C. Biomass is highest in the tropics, decreasing in the sub-tropics and increasing slightly towards the poles. There are, however, limitations on the dataset; abundance observations have good coverage except in the South Pacific mid latitudes, but biomass observation coverage is only good at high latitudes. Biomass is restricted to data that is originally given in carbon or to data that can be converted from abundance to carbon. Carbon conversions from abundance are restricted in the most part by the lack of information on the size of the

  16. Distribution of known macrozooplankton abundance and biomass in the global ocean

    NASA Astrophysics Data System (ADS)

    Moriarty, R.; Buitenhuis, E. T.; Le Quéré, C.; Gosselin, M.-P.

    2013-07-01

    Macrozooplankton are an important link between higher and lower trophic levels in the oceans. They serve as the primary food for fish, reptiles, birds and mammals in some regions, and play a role in the export of carbon from the surface to the intermediate and deep ocean. Little, however, is known of their global distribution and biomass. Here we compiled a dataset of macrozooplankton abundance and biomass observations for the global ocean from a collection of four datasets. We harmonise the data to common units, calculate additional carbon biomass where possible, and bin the dataset in a global 1 × 1 degree grid. This dataset is part of a wider effort to provide a global picture of carbon biomass data for key plankton functional types, in particular to support the development of marine ecosystem models. Over 387 700 abundance data and 1330 carbon biomass data have been collected from pre-existing datasets. A further 34 938 abundance data were converted to carbon biomass data using species-specific length frequencies or using species-specific abundance to carbon biomass data. Depth-integrated values are used to calculate known epipelagic macrozooplankton biomass concentrations and global biomass. Global macrozooplankton biomass, to a depth of 350 m, has a mean of 8.4 μg C L-1, median of 0.2 μg C L-1 and a standard deviation of 63.5 μg C L-1. The global annual average estimate of macrozooplankton biomass in the top 350 m, based on the median value, is 0.02 Pg C. There are, however, limitations on the dataset; abundance observations have good coverage except in the South Pacific mid-latitudes, but biomass observation coverage is only good at high latitudes. Biomass is restricted to data that is originally given in carbon or to data that can be converted from abundance to carbon. Carbon conversions from abundance are restricted by the lack of information on the size of the organism and/or the absence of taxonomic information. Distribution patterns of global

  17. Background concentrations of polychlorinated dibenzo-p-dioxins, dibenzofurans, and biphenyls in the global oceanic atmosphere.

    PubMed

    Morales, Laura; Dachs, Jordi; González-Gaya, Belén; Hernán, Gema; Abalos, Manuela; Abad, Esteban

    2014-09-01

    The remote oceans are among the most pristine environments in the world, away from sources of anthropogenic persistent organic pollutants (POP), but nevertheless recipients of atmospheric deposition of POPs that have undergone long-range atmospheric transport (LRAT). In this work, the background occurrence of gas and aerosol phase polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin like polychlorinated biphenyls (dl-PCB) is evaluated for the first time in the atmosphere of the tropical and subtropical Atlantic, Pacific, and Indian oceans. Thirty-nine air samples were collected during the eight-month Malaspina circumnavigation cruise onboard the R/V Hespérides. The background levels of dioxins and dl-PCBs remained very low and in many cases very close to or below the limit of detection. Expectedly, the levels of PCBs were higher than dioxins, PCB#118 being the most abundant compound. In the particular case of dioxins, octachlorodibenzo-p-dioxin (OCDD) was the most abundant PCDD/F congener. Distribution of dl-PCB is dominated by the gas phase, while for PCDD/F the aerosol phase concentrations were higher, particularly for the more hydrophobic congeners. The Atlantic Ocean presented on average the highest PCDD/F and dl-PCB concentrations, being lower in the southern hemisphere. The assessment of air mass back trajectories show a clear influence of continental source regions, and lower concentrations when the air mass has an oceanic origin. In addition, the samples affected by an oceanic air mass are characterized by a lower contribution of the less chlorinated dioxins in comparison with the furans, consistent with the reported higher reaction rate constants of dibenzo-p-dioxins with OH radicals than those of dibenzofurans. The total dry atmospheric deposition of aerosol-bound ∑PCDD/F and ∑dl-PCB to the global oceans was estimated to be 354 and 896 kg/year, respectively. PMID:25083749

  18. An automatic precipitation phase distinction algorithm for optical disdrometer data over the global ocean

    NASA Astrophysics Data System (ADS)

    Burdanowitz, J.; Klepp, C.; Bakan, S.

    2015-12-01

    The lack of high quality in situ surface precipitation data over the global ocean so far limits the capability to validate satellite precipitation retrievals. The first systematic ship-based surface precipitation dataset OceanRAIN (Ocean Rainfall And Ice-phase precipitation measurement Network) aims at providing a comprehensive statistical basis of in situ precipitation reference data from optical disdrometers at 1 min resolution deployed on various research vessels (RVs). Deriving the precipitation rate for rain and snow requires a priori knowledge of the precipitation phase (PP). Therefore, we present an automatic PP distinction algorithm using available data based on more than four years of atmospheric measurements onboard RV Polarstern that covers all climatic regions of the Atlantic Ocean. A time-consuming manual PP distinction within the OceanRAIN post-processing serves as reference, mainly based on 3 hourly present weather information from a human observer. For automation, we find that the combination of air temperature, relative humidity and 99th percentile of the particle diameter predicts best the PP with respect to the manually determined PP. Excluding mixed-phase, this variable combination reaches an accuracy of 91 % when compared to the manually determined PP for about 149 000 min of precipitation from RV Polarstern. Including mixed-phase (165 000 min), 81.2 % accuracy are reached with a slight snow overprediction bias of 0.93 for two independent PP distributions. In that respect, a method using two independent PP distributions outperforms a method based on only one PP distribution. The new statistical automatic PP distinction method significantly speeds up the data post-processing within OceanRAIN while introducing an objective PP probability for each PP at 1 min resolution.

  19. An automatic precipitation-phase distinction algorithm for optical disdrometer data over the global ocean

    NASA Astrophysics Data System (ADS)

    Burdanowitz, Jörg; Klepp, Christian; Bakan, Stephan

    2016-04-01

    The lack of high-quality in situ surface precipitation data over the global ocean so far limits the capability to validate satellite precipitation retrievals. The first systematic ship-based surface precipitation data set OceanRAIN (Ocean Rainfall And Ice-phase precipitation measurement Network) aims at providing a comprehensive statistical basis of in situ precipitation reference data from optical disdrometers at 1 min resolution deployed on various research vessels (RVs). Deriving the precipitation rate for rain and snow requires a priori knowledge of the precipitation phase (PP). Therefore, we present an automatic PP distinction algorithm using available data based on more than 4 years of atmospheric measurements onboard RV Polarstern that covers all climatic regions of the Atlantic Ocean. A time-consuming manual PP distinction within the OceanRAIN post-processing serves as reference, mainly based on 3-hourly present weather information from a human observer. For automation, we find that the combination of air temperature, relative humidity, and 99th percentile of the particle diameter predicts best the PP with respect to the manually determined PP. Excluding mixed phase, this variable combination reaches an accuracy of 91 % when compared to the manually determined PP for 149 635 min of precipitation from RV Polarstern. Including mixed phase (165 632 min), an accuracy of 81.2 % is reached for two independent PP distributions with a slight snow overprediction bias of 0.93. Using two independent PP distributions represents a new method that outperforms the conventional method of using only one PP distribution to statistically derive the PP. The new statistical automatic PP distinction method considerably speeds up the data post-processing within OceanRAIN while introducing an objective PP probability for each PP at 1 min resolution.

  20. Global Seasonal Climatologies of Ocean Chlorophyll: Blending In situ and Satellite Data for the CZCS Era

    NASA Technical Reports Server (NTRS)

    Gregg, Watson W.; Conkright, Margarita E.

    1999-01-01

    The historical archives of in situ (National Oceanographic Data Center) and satellite (Coastal Zone Color Scanner) chlorophyll data were combined using the blended analysis method of Reynolds [1988] in an attempt to construct an improved climatological seasonal representation of global chlorophyll distributions. The results of the blended analysis differed dramatically from the CZCS representation: global chlorophyll estimates increased 8-35% in the blended analysis depending upon season. Regional differences were even larger, up to 140% in the equatorial Indian Ocean in summer (during the southwest monsoon). Tropical Pacific chlorophyll values increased 25-41%. The results suggested that the CZCS generally underestimates chlorophyll. Regional and seasonal differences in the blended analysis were sufficiently large as to produce a different representation of global chlorophyll distributions than otherwise inferred from CZCS data alone. Analyses of primary production and biogeochemical cycles may be substantially impacted by these results.

  1. RTOPO-1: A consistent dataset for Antarctic ice shelf topography and global ocean bathymetry

    NASA Astrophysics Data System (ADS)

    Timmermann, Ralph

    2010-05-01

    Sub-ice shelf circulation and freezing/melting rates depend critically on an accurate and consistent representation of cavity geometry (i.e. ice-shelf draft and ocean bathymetry). Existing global or pan-Antarctic data sets have turned out to contain various inconsistencies and inaccuracies. The goal of this work is to compile independent regional fields into a global data set. We use the S-2004 global 1-minute bathymetry as the backbone and add an improved version of the BEDMAP topography for an area that roughly coincides with the Antarctic continental shelf. Locations of the merging line have been carefully adjusted in order to get the best out of each data set. High-resolution gridded data for the Amery, Fimbul, Filchner-Ronne, Larsen C and George VI Ice Shelves and for Pine Island Glacier have been carefully merged into the ambient ice and ocean topographies. Multibeam ship survey data for bathymetry in the former Larsen B cavity and the southeastern Bellingshausen Sea have been obtained from the data centers of Alfred Wegener Institute (AWI), British Antarctic Survey (BAS) and Lamont-Doherty Earth Observatory (LDEO), gridded, and again carefully merged into the existing bathymetry map. The resulting global 1-minute data set contains consistent masks for open ocean, grounded ice, floating ice, and bare land surface. The Ice Shelf Cavern Geometry Team: Anne Le Brocq, Tara Deen, Eugene Domack, Pierre Dutrieux, Ben Galton-Fenzi, Dorothea Graffe, Hartmut Hellmer, Angelika Humbert, Daniela Jansen, Adrian Jenkins, Astrid Lambrecht, Keith Makinson, Fred Niederjasper, Frank Nitsche, Ole Anders Nøst, Lars Henrik Smedsrud, and Walter Smith

  2. Global biogeophysical interactions between historical deforestation and climate through land surface albedo and interactive ocean

    NASA Astrophysics Data System (ADS)

    Wang, Ye

    2015-11-01

    Deforestation is expanding and accelerating into the remaining areas of undisturbed forest, and the quality of the remaining forests is declining today. Assessing the climatic impacts of deforestation can help to rectify this alarming situation. In this paper, how historical deforestation may affect global climate through interactive ocean and surface albedo is examined using an Earth system model of intermediate complexity (EMIC). Control and anomaly integrations are performed for 1000 years. In the anomaly case, cropland is significantly expanded since AD 1700. The response of climate in deforested areas is not uniform between the regions. In the background of a global cooling of 0.08 °C occurring with cooler surface air above 0.4 °C across 30° N to 75° N from March to September, the surface albedo increase has a global cooling effect in response to global-scale replacement of forests by cropland, especially over northern mid-high latitudes. The northern mid-latitude (30° N-60° N) suffers a prominent cooling in June, suggesting that this area is most sensitive to cropland expansion through surface albedo. Most regions show a consistent trend between the overall cooling in response to historical deforestation and its resulting cooling due to surface albedo anomaly. Furthermore, the effect of the interactive ocean on shaping the climate response to deforestation is greater than that of prescribed SSTs in most years with a maximum spread of 0.05 °C. This difference is more prominent after year 1800 than that before due to the more marked deforestation. These findings show the importance of the land cover change and the land surface albedo, stressing the necessity to analyze other biogeophysical processes of deforestation using interactive ocean.

  3. Evaluation of Global Ocean Data Assimilation Experiment products on South Florida nested simulations with the Hybrid Coordinate Ocean Model

    NASA Astrophysics Data System (ADS)

    Kourafalou, Vassiliki H.; Peng, Ge; Kang, Heesook; Hogan, Patrick J.; Smedstad, Ole-Martin; Weisberg, Robert H.

    2009-02-01

    The South Florida Hybrid Coordinate Ocean Model (SoFLA-HYCOM) encompasses a variety of coastal regions (the broad Southwest Florida shelf, the narrow Atlantic Keys shelf, the shallow Florida Bay, and Biscayne Bay) and deep regions (the Straits of Florida), including Marine Protected Areas (the Florida Keys Marine Sanctuary and the Dry Tortugas Ecological Reserve). The presence of the strong Loop Current/Florida Current system and associated eddies connects the local and basin-wide dynamics. A multi-nested approach has been developed to ensure resolution of coastal-scale processes and proper interaction with the large scale flows. The simulations are free running and effects of data assimilation are introduced through boundary conditions derived from Global Ocean Data Assimilation Experiment products. The study evaluates the effects of boundary conditions on the successful hindcasting of circulation patterns by a nested model, applied on a dynamically and topographically complex shelf area. Independent (not assimilated) observations are employed for a quantitative validation of the numerical results. The discussion of the prevailing dynamics that are revealed in both modeled and observed patterns suggests the importance of topography resolution and local forcing on the inner shelf to middle shelf areas, while large scale processes are found to dominate the outer shelf flows. The results indicate that the successful hindcasting of circulation patterns in a coastal area that is characterized by complex topography and proximity to a large scale current system requires a dynamical downscaling approach, with simulations that are nested in a hierarchy of data assimilative outer models.

  4. Prediction of the fate of radioactive material in the South Pacific Ocean using a global high-resolution ocean model.

    PubMed

    Hazell, Douglas R; England, Matthew H

    2003-01-01

    We investigate the release of radioactive contaminants from Moruroa Atoll in a global high-resolution off-line model. The spread of tracer is studied in a series of simulations with varying release depths and time-scales, and into ocean velocity fields corresponding to long-term annual mean, seasonal, and interannually varying scenarios. In the instantaneous surface release scenarios we find that the incorporation of a seasonal cycle greatly influences tracer advection, with maximum concentrations still found within the French Polynesia region after 10 years. In contrast, the maximum trace is located in the southeast Pacific when long-term annual mean fields are used. This emphasizes the importance of the seasonal cycle in models of pollution dispersion on large scales. We further find that during an El Niño/Southern Oscillation (ENSO) event reduced currents in the region of Moruroa Atoll result in increased concentrations of radioactive material in French Polynesia, as direct flushing from the source is reduced. In terms of the sensitivity to tracer release time-rates, we find that a gradual input results in maximum concentrations in the near vicinity of French Polynesia. This contrasts the instantaneous-release scenarios, which see maximum concentrations and tracer spread across much of the South Pacific Ocean. For example, in as little as seven years radioactive contamination can reach the east coast of Australia diluted by only a factor of 1,000 of the initial concentration. A comparison of results is made with previous studies. Overall, we find much higher concentrations of radionuclides in the South Pacific than has previously been predicted using coarser-resolution models. PMID:12573864

  5. Global oceanic microseism sources as seen by seismic arrays and predicted by wave action models

    NASA Astrophysics Data System (ADS)

    Hillers, G.; Graham, N.; Landes, M.; Hubans, F.; Campillo, M.; Shapiro, N. M.; Paul, A.; Kedar, S.; Clayton, R. W.

    2010-12-01

    Estimated locations of P-wave microseism generation obtained from seismic arrays analyses are combined with ocean wave-wave interaction models to improve the understanding of microseism generation. Source regions of likely microseism generation are found by combining data from three different networks located in the northern hemisphere. For each array, teleseismic P-wave arrivals are extracted from station-station correlations of ambient noise associated with the secondary microseism peak. Estimates of the slowness and azimuth of the teleseismic body waves are obtained and source location probabilities are constructed by projecting these beamforming results to patches on the Earth's surface that represent likely source regions. The application of Longuet-Higgins' (LH) microseism excitation theory to hindcast ocean wave-wave interaction spectra combined with bathymetry has shown that microseism can be excited very locally in the deep oceans as a consequence of nonlinear atmosphere-ocean-seafloor interactions. We utilize this approach to identify the source mechanism and location associated with the body wave arrivals, and compare projection results from seismic array processing to predictions from globally distributed ocean wave-wave interaction intensities. Based on this technique we observe a number of previously undocumented potential source regions, such as the oceans south of Madagascar, or the southern tip of Australia. We find that spatial patterns of strong excitation generally agrees with the inferred source projections based on 12-day averaging noise correlations. Details of the distributions depend, however, on averaging choices applied to the 3-hourly sampled oceanic excitation functions. We therefore focus on the sensitivity and stability of the resulting spatio temporal correlations to choices of averaging, considering the mapping of temporally variable excitations into results of the array beamforming analysis. More specifically, we investigate to

  6. Clathrate hydrate stability models for Titan: implications for a global subsurface ocean

    NASA Astrophysics Data System (ADS)

    Basu Sarkar, D.; Elwood Madden, M.

    2013-12-01

    Titan is the only planetary body in the solar system, apart from the Earth, with liquid at its surface. Titan's changing rotational period suggests that a global subsurface ocean decouples the icy crust from the interior. Several studies predict the existence of such an internal ocean below an Ice I layer, ranging in depth between a few tens of kilometers to a few hundreds of kilometers, depending on the composition of the icy crust and liquid-ocean. While the overall density of Titan is well constrained, the degree of differentiation within the interior is unclear. These uncertainties lead to poor understanding of the volatile content of the moon. However, unlike other similar large icy moons like Ganymede and Callisto, Titan has a thick nitrogen atmosphere, with methane as the second most abundant constituent - 5% near the surface. Titan's atmosphere, surface, and interior are likely home to various compounds such as C2H6, CO2, Ar, N2 and CH4, capable of forming clathrate hydrates. In addition, the moon has low temperature and low-to-high pressure conditions required for clathrate formation. Therefore the occurrence of extensive multicomponent hydrates may effect the composition of near-surface materials, the subsurface ocean, as well as the atmosphere. This work uses models of hydrate stability for a number of plausible hydrate formers including CH4, C2H6, CH4 + C2H6 and CH4 + NH3, and equilibrium geothermal gradients for probable near-surface materials to delineate the lateral and vertical extent of clathrate hydrate stability zones for Titan. By comparing geothermal gradients with clathrate stability fields for these systems we investigate possible compositions of Titan's global subsurface ocean. Preliminary model results indicate that ethane hydrates or compound hydrates of ethane and methane could be destabilized within the proposed depth range of the internal ocean, while methane/ammonia or pure methane hydrates may not be affected. Therefore, ethane or

  7. How essential are Argo observations to constrain a global ocean data assimilation system?

    NASA Astrophysics Data System (ADS)

    Turpin, V.; Remy, E.; Le Traon, P. Y.

    2016-02-01

    Observing system experiments (OSEs) are carried out over a 1-year period to quantify the impact of Argo observations on the Mercator Ocean 0.25° global ocean analysis and forecasting system. The reference simulation assimilates sea surface temperature (SST), SSALTO/DUACS (Segment Sol multi-missions dALTimetrie, d'orbitographie et de localisation précise/Data unification and Altimeter combination system) altimeter data and Argo and other in situ observations from the Coriolis data center. Two other simulations are carried out where all Argo and half of the Argo data are withheld. Assimilating Argo observations has a significant impact on analyzed and forecast temperature and salinity fields at different depths. Without Argo data assimilation, large errors occur in analyzed fields as estimated from the differences when compared with in situ observations. For example, in the 0-300 m layer RMS (root mean square) differences between analyzed fields and observations reach 0.25 psu and 1.25 °C in the western boundary currents and 0.1 psu and 0.75 °C in the open ocean. The impact of the Argo data in reducing observation-model forecast differences is also significant from the surface down to a depth of 2000 m. Differences between in situ observations and forecast fields are thus reduced by 20 % in the upper layers and by up to 40 % at a depth of 2000 m when Argo data are assimilated. At depth, the most impacted regions in the global ocean are the Mediterranean outflow, the Gulf Stream region and the Labrador Sea. A significant degradation can be observed when only half of the data are assimilated. Therefore, Argo observations matter to constrain the model solution, even for an eddy-permitting model configuration. The impact of the Argo floats' data assimilation on other model variables is briefly assessed: the improvement of the fit to Argo profiles do not lead globally to unphysical corrections on the sea surface temperature and sea surface height. The main conclusion

  8. Seasonal prediction of global sea level anomalies using an ocean-atmosphere dynamical model

    NASA Astrophysics Data System (ADS)

    Miles, Elaine R.; Spillman, Claire M.; Church, John A.; McIntosh, Peter C.

    2014-10-01

    Advanced warning of extreme sea level events is an invaluable tool for coastal communities, allowing the implementation of management policies and strategies to minimise loss of life and infrastructure damage. This study is an initial attempt to apply a dynamical coupled ocean-atmosphere model to the prediction of seasonal sea level anomalies (SLA) globally for up to 7 months in advance. We assess the ability of the Australian Bureau of Meteorology's operational seasonal dynamical forecast system, the Predictive Ocean Atmosphere Model for Australia (POAMA), to predict seasonal SLA, using gridded satellite altimeter observation-based analyses over the period 1993-2010 and model reanalysis over 1981-2010. Hindcasts from POAMA are based on a 33-member ensemble of seasonal forecasts that are initialised once per month for the period 1981-2010. Our results show POAMA demonstrates high skill in the equatorial Pacific basin and consistently exhibits more skill globally than a forecast based on persistence. Model predictability estimates indicate there is scope for improvement in the higher latitudes and in the Atlantic and Southern Oceans. Most characteristics of the asymmetric SLA fields generated by El-Nino/La Nina events are well represented by POAMA, although the forecast amplitude weakens with increasing lead-time.

  9. Global modeling study of potentially bioavailable iron input from shipboard aerosol sources to the ocean

    NASA Astrophysics Data System (ADS)

    Ito, Akinori

    2013-01-01

    Iron (Fe) is an essential element for phytoplankton. The majority of iron is transported from arid and semiarid regions to the open ocean, but it is mainly in an insoluble form. Since most aquatic organisms can take up iron only in the dissolved form, aerosol iron solubility is a key factor that can influence the air-sea CO2 fluxes and thus climate. Field observations have shown relatively high iron solubility in aerosols influenced by combustion sources, but specific emissions sources and their contributions to deposition fluxes largely remain uncertain. Here a global chemical transport model was used to investigate the effect of aerosol emissions from ship plumes on iron solubility in particles from the combustion and dust sources. The model results reveal that the oil combustion from shipping mainly contributes to high iron solubility (>10%) at low iron loading (1-110 ng m-3) observed over the high-latitude North Atlantic Ocean, rather than the other combustion sources from continental industrialized regions. Due to continuing growth in global shipping and no regulations regarding particles emissions over the open ocean, the input of potentially bioavailable iron from ship plumes is likely to increase during the next century. The model results suggest that deposition of soluble iron from ships in 2100 contributes 30-60% of the soluble iron deposition over the high-latitude North Atlantic and North Pacific.

  10. Assimilation of oceanic observations in a global coupled Earth system model with the SEIK filter

    NASA Astrophysics Data System (ADS)

    Brune, Sebastian; Nerger, Lars; Baehr, Johanna

    2015-12-01

    We present results from the assimilation of observed oceanic 3-D temperature and salinity fields into the global coupled Max Planck Institute Earth system model with the SEIK filter from January 1996 to December 2010. Our study is part of an effort to perform and evaluate assimilation and prediction within the same coupled climate model without the use of re-analysis data. We use two assimilation setups, one where oceanic observations over the entire water column are assimilated, and one where only oceanic observations below 50 m depth are assimilated. We compare the results from both assimilations with an unconstrained control experiment. While we do not find significant improvements due to assimilation in terms of the root-mean-square error of simulated temperature, 0-700 m heat content, sea surface height (SSH), and the Atlantic meridional overturning circulation (AMOC) against observations, we find the variability in terms of correlation with observations significantly improved due to assimilation, most prominently in the tropical oceans. Improvements over the control experiment are stronger in the sub-50 m assimilation experiment and in integrated quantities (SSH, AMOC).

  11. Steady-state and transient modeling of tracer and nutrient distributions in the global ocean

    SciTech Connect

    Stocker, T.F.; Broecker, W.S.

    1993-03-08

    The balance of stable and decaying tracers was incorporated into a latitude-depth ocean circulation model which resolves the major ocean basin and is coupled to an atmospheric energy balance model. The modern distribution of radiocarbon and the analysis of artificial color tracers enabled the census of the deep water masses. We show that good agreement with the observation can be achieved if the surface forcing is modified. The same process could also account for long-term, large-scale changes of the global thermohaline circulation. Uptake rates of carbon are investigated using an inorganic carbon cycle model and performing 2 [times] CO[sub 2]-experiments. We prescribe the industrial evolution of pCO[sub 2] in the atmosphere from 1792 to 1988 and calculate the total flux of carbon into the world ocean. Results are in good agreement with two recent 3-dimensional model simulation. First results using an organic carbon cycle in this model are presented. Changes in the hydrological cycle can stabilize the thermohaline circulation in the Atlantic and enable simulation of climate events resembling the Younger Dryas. By adding the balance of radiocarbon the evolution of its atmospheric concentration is studied during rapid changes of deep ocean ventilation. A resumption of ventilation creates a rapid decrease of atmospheric radiocarbon which is able to mask the natural decay.

  12. Modeling the Natural Biogeochemical Cycle of Mercury in the Global Ocean

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Jaegle, L.; Thompson, L.; Emerson, S. R.; Deutsch, C. A.; Trossman, D. S.; Shao, A.

    2012-12-01

    The ocean plays an important role in the biogeochemical cycling of mercury (Hg) because of its large reservoir mass and re-emission flux via evasion. The currently available Hg models, including 2D slab, 1D column and 0D box model cannot fully resolve the marine Hg cycle because of the lack of the proper spatial resolution. In this work, we have implemented Hg biogeochemistry in a state-of-the-art 3D offline ocean tracer model (OFFTRAC). OFFTRAC simulates the evolution of three Hg species (Hg0aq, HgIIaq and HgPaq), which are diffused and advected in the ocean. Hg0aq and HgII aq are interconverted in the surface ocean via parameterized photochemical and biological redox processes. The partitioning between HgIIaq and HgPaq depends on the local levels of particulate organic carbon (POC). The sinking of HgPaq is parameterized by coupling with the nutrient phosphorous cycle simulated in OFFTRAC. The reduction of HgIIaq to Hg0aq in the anaerobic subsurface water is proportional to the remineralizaiton of POC. OFFTRAC is coupled to a global simulation of the natural atmospheric Hg cycle in the GEOS-Chem chemical transport model. The GEOS-Chem simulation includes a geogenic source and provides the atmospheric deposition flux of HgII to the ocean and atmospheric Hg0 concentrations. The riverine input of Hg is calculated based on the climatological monthly mean fresh water discharge from continental to ocean and the average soil concentrations near the river mouth. The results show that the riverine input enhances Hg concentrations at surface by a factor of 2-3 near large river mouths and nearby coastal regions. The riverine input approximately doubles surface Hg concentration over the Arctic because of the small basin volume. In the deep ocean, which is not influenced by anthropogenic emissions, the model results (1.1±0.3 pM) generally agree with the observed present-day total Hg concentration profiles (1.4±0.9 pM). In the surface ocean, observations show average total Hg

  13. Global Model of the Integrated Strength of Oceanic Lithosphere and Ridge-push Transmission

    NASA Astrophysics Data System (ADS)

    Mahatsente, R.

    2014-12-01

    Global models of the integrated lithospheric strength of oceanic plates and ridge-push force are presented. To assess the transmission of ridge-push related stress in oceanic plates, ridge-push force and lithospheric strength are compared. The integrated strength of oceanic plate has been estimated using plate cooling model and relevant rheology of the crust and upper mantle. The strength analysis includes Low-Temperature Plasticity (LTP) and assumes a range of possible tectonic conditions and rheology in the plates. The ridge-push force has been derived from thermal state of oceanic lithosphere, crustal age and seafloor depth data. The results of modelling show that both lithospheric strength and ridge-push force are age dependent. Old oceanic plates can be as strong as ~ 11 TN m-1. For plates of the same age, the magnitude of ridge-push force is in the order of ~ 3.5 TN m-1.The transmission of ridge-push is mainly controlled by the rheology and predominant tectonic condition in the plates. If the rheology of oceanic lithosphere is dry, the estimated lithospheric strength is larger than the ridge-push force at all ages for compressional tectonic regimes and at old ages for extension (> 75 Ma). Under such consideration, the ridge-push related stresses may not dissipate in a form of intraplate deformation. Instead, the stresses may be transmitted in the plate. If an oceanic lithosphere has wet rheology, the strength of young plates (< 75 Ma) is much less than the ridge-push force for extensional and compressional tectonic regimes. Consequently, the stress associated with ridge-push may result in intraplate deformation. This depends, however, on the balance of force resulting from far field forces, basal shear traction and Gravitational Potential Energy of elevated regions. In particular, strong basal shear traction can balance the ridge-push force, and as a result, the oceanic lithosphere may respond by deformation. The consideration of LTP in the upper mantle has

  14. Adaptive wavelet simulation of global ocean dynamics using a new Brinkman volume penalization

    NASA Astrophysics Data System (ADS)

    Kevlahan, N. K.-R.; Dubos, T.; Aechtner, M.

    2015-12-01

    In order to easily enforce solid-wall boundary conditions in the presence of complex coastlines, we propose a new mass and energy conserving Brinkman penalization for the rotating shallow water equations. This penalization does not lead to higher wave speeds in the solid region. The error estimates for the penalization are derived analytically and verified numerically for linearized one-dimensional equations. The penalization is implemented in a conservative dynamically adaptive wavelet method for the rotating shallow water equations on the sphere with bathymetry and coastline data from NOAA's ETOPO1 database. This code could form the dynamical core for a future global ocean model. The potential of the dynamically adaptive ocean model is illustrated by using it to simulate the 2004 Indonesian tsunami and wind-driven gyres.

  15. Global ocean tide models on the eve of Topex/Poseidon

    SciTech Connect

    Ray, R.D. )

    1993-03-01

    Some existing global ocean tide models that can provide tide corrections to Topex/Poseidon altimeter data are described. Emphasis is given to the Schwiderski and Cartwright-Ray models, as these are the most comprehensive, highest resolution models, but other models that will soon appear are mentioned. Differences between models for M[sub 2] often exceed 10 cm over vast stretches of the ocean. Comparisons to 80 selected pelagic and island gauge measurements indicate the Schwiderski model is more accurate for the major solar tides, Cartwright-Ray for the major lunar tides. The adequacy of available tide models for studying basin-scale motions is probably marginal at best. The subject, however, is in a state of flux, and one may expect rapid advancement over the next several years.

  16. Observing Global Ocean Circulation From Space: The First Year's Results From the TOPEX/POSEIDON Mission

    NASA Technical Reports Server (NTRS)

    Fu, L. -L.

    1993-01-01

    The joint U.S./France TOPEX/Poseidon satellite was launched on August 10, 1992, and became operational 43 days later. The major goal of the mission is to use a radar altimeter system for making precise measurements of the height of the sea surface for the study of the dynamics of large-scale ocean circulation, which is a key to understanding global climate change. Additionally, the data are used for studying ocean tides and marine geophysics. The radar altimeter also measures wave height and wind speed. The mission is being conducted to optimize the sea surface height measurements for a minimum of three years. The primary objective of the first six months of the mission was to calibrate and validate the mission's measurements...

  17. Observing Global Ocean Circulation From Space: The First Year's Results From the TOPEX/POSEIDON Mission

    NASA Technical Reports Server (NTRS)

    Fu, L. -L.

    1993-01-01

    The joint U.S./France TOPEX/Poseidon satellite was launched on August 10, 1992, and became operational 42 days later. The major goal of the mission is to use a radar altimeter system for making precise measurements of the height of the sea surface for the study of the dynamics of large-scale ocean circulation, which is a key to understanding global climate change. Additionally, the data are used for studying ocean tides and marine geophysics. The radar altimeter also measures wave height and wind speed. The mission is being conducted to optimize the sea surface height measurements for a minimum of three years. The primary objective of the first six months of the mission was to calibrate and validate the mission's measurements. The verification results indicate that all the measurement objectives have been met...

  18. A Time Series of Sea Surface Nitrate and Nitrate based New Production in the Global Oceans

    NASA Astrophysics Data System (ADS)

    Goes, J. I.; Fargion, G. S.; Gomes, H. R.; Franz, B. A.

    2014-12-01

    With support from NASA's MEaSUREs program, we are developing algorithms for two innovative satellite-based Earth Science Data Records (ESDRs), one Sea Surface Nitrate (SSN) and the other, Nitrate based new Production (NnP). Newly developed algorithms will be applied to mature ESDRs of Chlorophyll a and SST available from NASA, to generate maps of SSN and NnP. Our proposed ESDRs offer the potential of greatly improving our understanding of the role of the oceans in global carbon cycling, earth system processes and climate change, especially for regions and seasons which are inaccessible to traditional shipboard studies. They also provide an innovative means for validating and improving coupled ecosystem models that currently rely on global maps of nitrate generated from multi-year data sets. To aid in our algorithm development efforts and to ensure that our ESDRs are truly global in nature, we are currently in the process of assembling a large database of nutrients from oceanographic institutions all over the world. Once our products are developed and our algorithms are fine-tuned, large-scale data production will be undertaken in collaboration with NASA's Ocean Biology Processing Group (OPBG), who will make the data publicly available first as evaluation products and then as mature ESDRs.

  19. Coupled biophysical global ocean model and molecular genetic analyses identify multiple introductions of cryptogenic species.

    PubMed

    Dawson, Michael N; Sen Gupta, Alex; England, Matthew H

    2005-08-23

    The anthropogenic introduction of exotic species is one of the greatest modern threats to marine biodiversity. Yet exotic species introductions remain difficult to predict and are easily misunderstood because knowledge of natural dispersal patterns, species diversity, and biogeography is often insufficient to distinguish between a broadly dispersed natural population and an exotic one. Here we compare a global molecular phylogeny of a representative marine meroplanktonic taxon, the moon-jellyfish Aurelia, with natural dispersion patterns predicted by a global biophysical ocean model. Despite assumed high dispersal ability, the phylogeny reveals many cryptic species and predominantly regional structure with one notable exception: the globally distributed Aurelia sp.1, which, molecular data suggest, may occasionally traverse the Pacific unaided. This possibility is refuted by the ocean model, which shows much more limited dispersion and patterns of distribution broadly consistent with modern biogeographic zones, thus identifying multiple introductions worldwide of this cryptogenic species. This approach also supports existing evidence that (i) the occurrence in Hawaii of Aurelia sp. 4 and other native Indo-West Pacific species with similar life histories is most likely due to anthropogenic translocation, and (ii) there may be a route for rare natural colonization of northeast North America by the European marine snail Littorina littorea, whose status as endemic or exotic is unclear. PMID:16103373

  20. A New Estimate for Global Hydrothermal Exchange Between the Oceans and Lithosphere

    NASA Astrophysics Data System (ADS)

    Hasterok, D. P.

    2013-12-01

    We revise the estimated global power deficit due to ventilated hydrothermal circulation (8.0 TW) using an updated global heat flow dataset with >14000 oceanic measurements and a new conductive cooling model of the oceanic lithosphere. This study differs from previous estimates by taking into account (1) non-Gaussian statistics, (2) an improved seafloor age model, (3) a new plate cooling model calibrated directly to heat flow, and (4) the effect of sediment cover on the heat flow deficit and ventilated cutoff age. We obtain the maximum heat flow deficit (difference between predicted and observed) when the data are separated by seafloor areas with <400 m and 400 m of sediment cover. The estimated power deficit (integrated heat flow deficit with respect to area) for areas of thin (<400 m) sediment cover is 7.8 TW and for areas of thick (400 m) is 0.2 TW. The total power deficit, 8.0 TW with 50% of estimates falling between 5.0 and 10.0 TW, represents a 30% reduction in magnitude compared with previous heat flow and fluid flow based estimates. Regions with thick, 400 m, sediment cover experience half the heat flow deficit for one-third of the duration (25 Ma) of regions with thin sediment cover (75 Ma). Based on this study, vigorous fluid exchange between the oceans and seafloor redistributes 30% of heat lost through young oceanic crust. Spatial variation in heat flow deficit relative to estimated conductive heat loss. Variations are calibrated to observed heat flow and constrained by sediment thickness variations.

  1. Interactive momentum flux forcing over sea ice in a global ocean GCM

    NASA Astrophysics Data System (ADS)

    StöSsel, Achim; Cheon, Woo-Geun; Vihma, Timo

    2008-05-01

    The sensitivity of Southern Ocean sea ice to the strength of the atmospheric momentum forcing is investigated in the framework of a global ocean general circulation model. In contrast to the usual approach of having the momentum flux just depend on the wind speed and a constant drag coefficient, the newly introduced momentum flux driving sea ice considers the local stratification and roughness over ice in one case, and the flux-aggregated stratification and roughness using the blending-height concept in the other case. While both cases thus allow for an interactive feedback, only the latter case accounts for the subgrid-scale heterogeneity of the sea-ice pack. In particular, the sea-ice feedback is in the former case only provided by the simulated ice thickness, affecting the surface temperature and local stratification, while in the latter case it is also determined by the ice concentration. Both parameterizations yield predominantly statically stable, but dynamically unstable conditions at any instant over the wintertime sea-ice pack. In the winter mean, statically and dynamically unstable conditions prevail over coastal polynyas, and lead to a positive feedback with increased momentum flux. The larger momentum flux enhances the along and offshore ice drift, leading to corresponding changes in the winter-mean ice-thickness distribution, a reduction in coastal ice concentration, and an increase of heat loss due to sensible heat flux. In the case where surface heterogeneity is accounted for, the impact of the lower coastal ice concentration leads to a larger momentum flux than in the homogeneous case. The long-term deep-ocean properties are only affected when in the heterogeneous case the form drag is raised by increasing the ice freeboard and decreasing the maximum ice concentration. Only the combination of both yields a significant increase of Antarctic Bottom Water formation, as reflected by a long-term cooling and freshening of the global deep-ocean properties.

  2. Future habitat suitability for coral reef ecosystems under global warming and ocean acidification

    PubMed Central

    Couce, Elena; Ridgwell, Andy; Hendy, Erica J

    2013-01-01

    Rising atmospheric CO2 concentrations are placing spatially divergent stresses on the world's tropical coral reefs through increasing ocean surface temperatures and ocean acidification. We show how these two stressors combine to alter the global habitat suitability for shallow coral reef ecosystems, using statistical Bioclimatic Envelope Models rather than basing projections on any a priori assumptions of physiological tolerances or fixed thresholds. We apply two different modeling approaches (Maximum Entropy and Boosted Regression Trees) with two levels of complexity (one a simplified and reduced environmental variable version of the other). Our models project a marked temperature-driven decline in habitat suitability for many of the most significant and bio-diverse tropical coral regions, particularly in the central Indo-Pacific. This is accompanied by a temperature-driven poleward range expansion of favorable conditions accelerating up to 40–70 km per decade by 2070. We find that ocean acidification is less influential for determining future habitat suitability than warming, and its deleterious effects are centered evenly in both hemispheres between 5° and 20° latitude. Contrary to expectations, the combined impact of ocean surface temperature rise and acidification leads to little, if any, degradation in future habitat suitability across much of the Atlantic and areas currently considered ‘marginal’ for tropical corals, such as the eastern Equatorial Pacific. These results are consistent with fossil evidence of range expansions during past warm periods. In addition, the simplified models are particularly sensitive to short-term temperature variations and their projections correlate well with reported locations of bleaching events. Our approach offers new insights into the relative impact of two global environmental pressures associated with rising atmospheric CO2 on potential future habitats, but greater understanding of past and current controls on

  3. Review of electrochemical energy conversion and storage for ocean thermal and wind energy systems

    NASA Astrophysics Data System (ADS)

    Landgrebe, A. R.; Donley, S. W.

    A literature review on electrochemical storage techniques related to ocean thermal (OTEC) and wind energy conversion systems (WECS) is presented. Battery use for WECS is foreseen because of siting size, variable capacity, quiet operation, and high efficiency; high cost and the necessity for further input voltage regulation is noted, as are prospects for technology transfer from existing programs for photovoltaic panel battery development. Fuel cells, which can run on hydrogen, ammonia, methanol, naphtha, etc., are encouraging because capacity increases are possible by simple addition of more fuel, and high thermal efficiency. Electrolytic use is seen as a cheap replacement source of electricity for metals refining and brine electrolysis. Systems of energy 'bridges' for OTEC plants, to transmit power to users, are reviewed as redox-flow, lithium-water-air, and aluminum batteries, fuel cells, electrolytic hydrogen, methane, and ammonia production, and the use of OTECs as power sources for floating factories. Directions of future research are indicated, noting that WECS will be in commercial production by 1985, while OTEC is far term, around 2025.

  4. The Flexible Global Ocean-Atmosphere-Land system model, Spectral Version 2: FGOALS-s2

    NASA Astrophysics Data System (ADS)

    Bao, Qing; Lin, Pengfei; Zhou, Tianjun; Liu, Yimin; Yu, Yongqiang; Wu, Guoxiong; He, Bian; He, Jie; Li, Lijuan; Li, Jiandong; Li, Yangchun; Liu, Hailong; Qiao, Fangli; Song, Zhenya; Wang, Bin; Wang, Jun; Wang, Pengfei; Wang, Xiaocong; Wang, Zaizhi; Wu, Bo; Wu, Tongwen; Xu, Yongfu; Yu, Haiyang; Zhao, Wei; Zheng, Weipeng; Zhou, Linjiong

    2013-05-01

    The Flexible Global Ocean-Atmosphere-Land System model, Spectral Version 2 (FGOALS-s2) was used to simulate realistic climates and to study anthropogenic influences on climate change. Specifically, the FGOALS-s2 was integrated with Coupled Model Intercomparison Project Phase 5 (CMIP5) to conduct coordinated experiments that will provide valuable scientific information to climate research communities. The performances of FGOALS-s2 were assessed in simulating major climate phenomena, and documented both the strengths and weaknesses of the model. The results indicate that FGOALS-s2 successfully overcomes climate drift, and realistically models global and regional climate characteristics, including SST, precipitation, and atmospheric circulation. In particular, the model accurately captures annual and semi-annual SST cycles in the equatorial Pacific Ocean, and the main characteristic features of the Asian summer monsoon, which include a low-level southwestern jet and five monsoon rainfall centers. The simulated climate variability was further examined in terms of teleconnections, leading modes of global SST (namely, ENSO), Pacific Decadal Oscillations (PDO), and changes in 19th-20th century climate. The analysis demonstrates that FGOALS-s2 realistically simulates extra-tropical teleconnection patterns of large-scale climate, and irregular ENSO periods. The model gives fairly reasonable reconstructions of spatial patterns of PDO and global monsoon changes in the 20th century. However, because the indirect effects of aerosols are not included in the model, the simulated global temperature change during the period 1850-2005 is greater than the observed warming, by 0.6°C. Some other shortcomings of the model are also noted.

  5. Local Observations, Global Connections: An Educational Program Using Ocean Networks Canada's Community-Based Observatories

    NASA Astrophysics Data System (ADS)

    Pelz, M.; Hoeberechts, M.; Ewing, N.; Davidson, E.; Riddell, D. J.

    2014-12-01

    Schools on Canada's west coast and in the Canadian Arctic are participating in the pilot year of a novel educational program based on analyzing, understanding and sharing ocean data collected by cabled observatories. The core of the program is "local observations, global connections." First, students develop an understanding of ocean conditions at their doorstep through the analysis of community-based observatory data. Then, they connect that knowledge with the health of the global ocean by engaging with students at other schools participating in the educational program and through supplemental educational resources. Ocean Networks Canada (ONC), an initiative of the University of Victoria, operates cabled ocean observatories which supply continuous power and Internet connectivity to a broad suite of subsea instruments from the coast to the deep sea. This Internet connectivity permits researchers, students and members of the public to download freely available data on their computers anywhere around the globe, in near real-time. In addition to the large NEPTUNE and VENUS cabled observatories off the coast of Vancouver Island, British Columbia, ONC has been installing smaller, community-based cabled observatories. Currently two are installed: one in Cambridge Bay, Nunavut and one at Brentwood College School, on Mill Bay in Saanich Inlet, BC. Several more community-based observatories are scheduled for installation within the next year. The observatories support a variety of subsea instruments, such as a video camera, hydrophone and water quality monitor and shore-based equipment including a weather station and a video camera. Schools in communities hosting an observatory are invited to participate in the program, alongside schools located in other coastal and inland communities. Students and teachers access educational material and data through a web portal, and use video conferencing and social media tools to communicate their findings. A series of lesson plans

  6. Dynamic ocean provinces: a multi-sensor approach to global marine ecophysiology

    NASA Astrophysics Data System (ADS)

    Dowell, M.; Campbell, J.; Moore, T.

    The concept of oceanic provinces or domains has existed for well over a century. Such systems, whether real or only conceptual, provide a useful framework for understanding the mechanisms controlling biological, physical and chemical processes and their interactions. Criteria have been established for defining provinces based on physical forcings, availability of light and nutrients, complexity of the marine food web, and other factors. In general, such classification systems reflect the heterogeneous nature of the ocean environment, and the effort of scientists to comprehend the whole system by understanding its various homogeneous components. If provinces are defined strictly on the basis of geospatial or temporal criteria (e.g., latitude zones, bathymetry, or season), the resulting maps exhibit discontinuities that are uncharacteristic of the ocean. While this may be useful for many purposes, it is unsatisfactory in that it does not capture the dynamic nature of fluid boundaries in the ocean. Boundaries fixed in time and space do not allow us to observe interannual or longer-term variability (e.g., regime shifts) that may result from climate change. The current study illustrates the potential of using fuzzy logic as a means of classifying the ocean into objectively defined provinces using properties measurable from satellite sensors (MODIS and SeaWiFS). This approach accommodates the dynamic variability of provinces which can be updated as each image is processed. We adopt this classification as the basis for parameterizing specific algorithms for each of the classes. Once the class specific algorithms have been applied, retrievals are then recomposed into a single blended product based on the "weighted" fuzzy memberships. This will be demonstrated through animations of multi-year time- series of monthly composites of the individual classes or provinces. The provinces themselves are identified on the basis of global fields of chlorophyll, sea surface temperature

  7. Global autocorrelation scales of the partial pressure of oceanic CO2

    NASA Astrophysics Data System (ADS)

    Li, Zhen; Adamec, David; Takahashi, Taro; Sutherland, Stewart C.

    2005-08-01

    A global database of approximately 1.7 million observations of the partial pressure of carbon dioxide in surface ocean waters (pCO2) collected between 1970 and 2003 is used to estimate its spatial autocorrelation structure. The patterns of the lag distance where the autocorrelation exceeds 0.8 is similar to patterns in the spatial distribution of the first baroclinic Rossby radius of deformation indicating that ocean circulation processes play a significant role in determining the spatial variability of pCO2. Separate calculations for times when the Sun is north and south of the equator revealed no obvious seasonal dependence of the spatial autocorrelation scales. The pCO2 measurements at Ocean Weather Station (OWS) "P" in the eastern subarctic Pacific (50°N, 145°W) is the only fixed location where an uninterrupted time series of sufficient length exists to calculate a meaningful temporal autocorrelation function for lags greater than a few days. The estimated temporal autocorrelation function at OWS "P" is highly variable. A spectral analysis of the longest four pCO2 time series indicates a high level of variability occurring over periods from the atmospheric synoptic to the maximum length of the time series, in this case 42 days. It is likely that a relative peak in variability with a period of 3-6 days is related to atmospheric synoptic period variability and ocean mixing events due to wind stirring. However, the short length of available time series makes identifying temporal relationships between pCO2 and atmospheric or ocean processes problematic.

  8. Atmospheric response to Indian Ocean Dipole forcing: changes of Southeast China winter precipitation under global warming

    NASA Astrophysics Data System (ADS)

    Zhang, Ling; Sielmann, Frank; Fraedrich, Klaus; Zhi, Xiefei

    2016-05-01

    To investigate the relationship between autumn Indian Ocean Dipole (IOD) events and the subsequent winter precipitation in Southeast China (SEC), observed fields of monthly precipitation, sea surface temperature (SST) and atmospheric circulation are subjected to a running and a maximum correlation analysis. The results show a significant change of the relevance of IOD for the early modulation of SEC winter precipitation in the 1980s. After 1980, positive correlations suggest prolonged atmospheric responses to IOD forcing, which are linked to an abnormal moisture supply initiated in autumn and extended into the subsequent winter. Under global warming two modulating factors are relevant: (1) an increase of the static stability has been observed suppressing vertical heat and momentum transports; (2) a positive (mid-level) cloud-radiation feedback jointly with the associated latent heating (apparent moisture sink Q2) explains the prolongation of positive as well as negative SST anomalies by conserving the heating (apparent heat source Q1) in the coupled atmosphere-ocean system. During the positive IOD events in fall (after 1980) the dipole heating anomalies in the middle and lower troposphere over the tropical Indian Ocean are prolonged to winter by a positive mid-level cloud-radiative feedback with latent heat release. Subsequently, thermal adaptation leads to an anticyclonic anomaly over Eastern India overlying the anomalous cooling SST of the tropical Eastern Indian Ocean enhancing the moisture flow from the tropical Indian Ocean through the Bay of Bengal into South China, following the northwestern boundary of the anticyclonic circulation anomaly over east India, thereby favoring abundant precipitation in SEC.

  9. A global perturbation to the sulfur cycle during the Toarcian Oceanic Anoxic Event

    NASA Astrophysics Data System (ADS)

    Gill, Benjamin C.; Lyons, Timothy W.; Jenkyns, Hugh C.

    2011-12-01

    The Mesozoic Era was punctuated by intervals of widespread anoxia within the ocean, termed oceanic anoxic events or OAEs. The chemostratigraphy of these intervals also contains evidence of transient perturbations to many biogeochemically important elemental cycles. Here we present high-resolution sulfur isotope data from three stratigraphic sections spanning the Toarcian Oceanic Anoxic Event (T-OAE) of the Early Jurassic. All sections show a similar increase in the sulfur isotope ratio of sulfate parallel to an overall positive excursion in carbon isotopes during the OAE interval. Based on forward box modeling, the sulfate-S isotope excursion can be generated by transiently increasing the burial rate of pyrite in marine sediments likely deposited under euxinic (i.e., anoxic and sulfidic) conditions in the water column. In addition, modeling shows that prolonged recovery of the δ 34S of seawater sulfate—at least 8 Ma after the initial rise associated with the OAE—was due to the relatively long residence time of sulfate in the Jurassic ocean; estimates from our modeling put the Toarcian marine sulfate concentrations at 4 to 8 mM. The similarity of the sulfur isotope records from the North European epicontinental (or epeiric) sea and Tethyan continental margin suggests that local modification of the marine sulfur isotope signal was minimal: a point explored with isotope mixing models. Importantly, our results indicate that the sulfur isotope excursion reflects a globally significant perturbation in the sulfur cycle and that pyrite burial in the North European Epeiric Seaway alone cannot account for the excursion. This study, along with recent work from other Phanerozoic intervals of widespread marine oxygen deficiency, confirms that the sulfur cycle can be perturbed significantly by enhanced pyrite burial during periods of prolonged oceanic anoxia/euxinia.

  10. How stationary are the internal tides in a high-resolution global ocean circulation model?

    NASA Astrophysics Data System (ADS)

    Shriver, Jay F.; Richman, James G.; Arbic, Brian K.

    2014-05-01

    The stationarity of the internal tides generated in a global eddy-resolving ocean circulation model forced by realistic atmospheric fluxes and the luni-solar gravitational potential is explored. The root mean square (RMS) variability in the M2 internal tidal amplitude is approximately 2 mm or less over most of the ocean and exceeds 2 mm in regions with larger internal tidal amplitude. The M2 RMS variability approaches the mean amplitude in weaker tidal areas such as the tropical Pacific and eastern Indian Ocean, but is smaller than the mean amplitude near generation regions. Approximately 60% of the variance in the complex M2 tidal amplitude is due to amplitude-weighted phase variations. Using the RMS tidal amplitude variations normalized by the mean tidal amplitude (normalized RMS variability (NRMS)) as a metric for stationarity, low-mode M2 internal tides with NRMS < 0.5 are stationary over 25% of the deep ocean, particularly near the generation regions. The M2 RMS variability tends to increase with increasing mean amplitude. However, the M2 NRMS variability tends to decrease with increasing mean amplitude, and regions with strong low-mode internal tides are more stationary. The internal tide beams radiating away from generation regions become less stationary with distance. Similar results are obtained for other tidal constituents with the overall stationarity of the constituent decreasing as the energy in the constituent decreases. Seasonal variations dominate the RMS variability in the Arabian Sea and near-equatorial oceans. Regions of high eddy kinetic energy are regions of higher internal tide nonstationarity.

  11. Evaluation of a global internal-tide resolving and submesoscale admitting ocean simulation

    NASA Astrophysics Data System (ADS)

    Ubelmann, C.; Menemenlis, D.; Fu, L. L.; Zhao, Z.

    2014-12-01

    We will present ongoing evaluation of a global ocean and sea ice configuration of the Massachusetts Institute of Technology general circulation model (MITgcm) that has 0.75 to 2.2 km horizontal grid spacing and 1-m thick vertical levels near the surface. Surface boundary conditions are from the 0.14-degree European Center for Medium-Range Weather Forecasts (ECMWF) atmospheric operational model analysis, starting in 2011, including atmospheric pressure forcing. The simulation also includes tidal forcing. A unique feature of this simulation is that we save hourly output of full 3-dimensional model prognostic variables, making it a remarkable tool for the study of ocean processes and for the simulation of satellite observations. Although this initial simulation was run without ocean data constraints, it already presents very interesting features and interactions between an exceptionally wide range of scales. The simulation resolves geostrophic eddies and internal tides and admits submesoscale variability and unbalanced dynamics such as internal waves at non-tidal frequencies.We will present some evaluation of these different components based on altimetry observations and moorings. As a first result, the internal tides for the major tidal components have overall realistic amplitudes and spatial patterns compared to independent analyses from altimetry, although some discrepancies arise in equatorial regions. Despite discrepancies with observations, this simulation already constitutes an extremely useful tool for ocean process studies and for satellite observation system experiments, for example, in preparation for the Surface Water and Ocean Topography (SWOT) mission. As a preliminary exercise, the simulation has been tested in the SWOT simulator developed at the Jet Propulsion Laboratory (Fu et al., in this session). Some illustrations of the challenges will be presented.

  12. Blunt ocean dynamical thermostat in response of tropical eastern Pacific SST to global warming

    NASA Astrophysics Data System (ADS)

    An, Soon-Il; Im, Seul-Hee

    2014-10-01

    Using an intermediate ocean-atmosphere coupled model (ICM) for the tropical Pacific, we investigated the role of the ocean dynamical thermostat (ODT) in regulating the tropical eastern Pacific sea surface temperature (SST) under global warming conditions. The external, uniformly distributed surface heating results in the cooling of the tropical eastern Pacific "cold tongue," and the amplitude of the cooling increases as more heat is added but not simply linearly. Furthermore, an upper bound for the influence of the equatorially symmetric surface heating on the cold tongue cooling exists. The additional heating beyond the upper bound does not cool the cold tongue in a systematic manner. The heat budget analysis suggests that the zonal advection is the primary factor that contributes to such nonlinear SST response. The radiative heating due to the greenhouse effect (hereafter, RHG) that is obtained from the multi-model ensemble of the Climate Model Intercomparison Project Phase III (CMIP3) was externally given to ICM. The RHG obtained from the twentieth century simulation intensified the cold tongue cooling and the subtropical warming, which were further intensified by the RHG from the doubled CO2 concentration simulation. However, the cold tongue cooling was significantly reduced and the negative SST response region was shrunken toward the equator by the RHG from the quadrupled CO2 concentration simulation, while the subtropical warming increased further. A systematic RHG forced experiment having the same spatial pattern of RHG from doubled CO2 concentration simulation with different amplitude of forcing revealed that the ocean dynamical response to global warming tended to enhance the cooling in the tropical eastern Pacific by virtue of meridional advection and upwelling; however, these cooling effects could not fully compensate a given RHG warming as the external forcing becomes larger. Moreover, the feedback by the zonal thermal advection actually exerted the

  13. Water mass age and aging driving chromophoric dissolved organic matter in the dark global ocean

    NASA Astrophysics Data System (ADS)

    Catalá, T. S.; Reche, I.; Álvarez, M.; Khatiwala, S.; Guallart, E. F.; Benítez-Barrios, V. M.; Fuentes-Lema, A.; Romera-Castillo, C.; Nieto-Cid, M.; Pelejero, C.; Fraile-Nuez, E.; Ortega-Retuerta, E.; Marrasé, C.; Álvarez-Salgado, X. A.

    2015-07-01

    The omnipresence of chromophoric dissolved organic matter (CDOM) in the open ocean enables its use as a tracer for biochemical processes throughout the global overturning circulation. We made an inventory of CDOM optical properties, ideal water age (τ), and apparent oxygen utilization (AOU) along the Atlantic, Indian, and Pacific Ocean waters sampled during the Malaspina 2010 expedition. A water mass analysis was applied to obtain intrinsic, hereinafter archetypal, values of τ, AOU, oxygen utilization rate (OUR), and CDOM absorption coefficients, spectral slopes and quantum yield for each one of the 22 water types intercepted during this circumnavigation. Archetypal values of AOU and OUR have been used to trace the differential influence of water mass aging and aging rates, respectively, on CDOM variables. Whereas the absorption coefficient at 325 nm (a325) and the fluorescence quantum yield at 340 nm (Φ340) increased, the spectral slope over the wavelength range 275-295 nm (S275-295) and the ratio of spectral slopes over the ranges 275-295 nm and 350-400 nm (SR) decreased significantly with water mass aging (AOU). Combination of the slope of the linear regression between archetypal AOU and a325 with the estimated global OUR allowed us to obtain a CDOM turnover time of 634 ± 120 years, which exceeds the flushing time of the dark ocean (>200 m) by 46%. This positive relationship supports the assumption of in situ production and accumulation of CDOM as a by-product of microbial metabolism as water masses turn older. Furthermore, our data evidence that global-scale CDOM quantity (a325) is more dependent on aging (AOU), whereas CDOM quality (S275-295, SR, Φ340) is more dependent on aging rate (OUR).

  14. A Comparison of Latent Heat Fluxes over Global Oceans for Four Flux Products

    NASA Technical Reports Server (NTRS)

    Chou, Shu-Hsien; Nelkin, Eric; Ardizzone, Joe; Atlas, Robert M.

    2003-01-01

    To improve our understanding of global energy and water cycle variability, and to improve model simulations of climate variations, it is vital to have accurate latent heat fluxes (LHF) over global oceans. Monthly LHF, 10-m wind speed (U10m), 10-m specific humidity (Q10h), and sea-air humidity difference (Qs-Q10m) of GSSTF2 (version 2 Goddard Satellite-based Surface Turbulent Fluxes) over global Oceans during 1992-93 are compared with those of HOAPS (Hamburg Ocean Atmosphere Parameters and Fluxes from Satellite Data), NCEP (NCEP/NCAR reanalysis). The mean differences, standard deviations of differences, and temporal correlation of these monthly variables over global Oceans during 1992-93 between GSSTF2 and each of the three datasets are analyzed. The large-scale patterns of the 2yr-mean fields for these variables are similar among these four datasets, but significant quantitative differences are found. The temporal correlation is higher in the northern extratropics than in the south for all variables, with the contrast being especially large for da Silva as a result of more missing ship data in the south. The da Silva has extremely low temporal correlation and large differences with GSSTF2 for all variables in the southern extratropics, indicating that da Silva hardly produces a realistic variability in these variables. The NCEP has extremely low temporal correlation (0.27) and large spatial variations of differences with GSSTF2 for Qs-Q10m in the tropics, which causes the low correlation for LHF. Over the tropics, the HOAPS LHF is significantly smaller than GSSTF2 by approx. 31% (37 W/sq m), whereas the other two datasets are comparable to GSSTF2. This is because the HOAPS has systematically smaller LHF than GSSTF2 in space, while the other two datasets have very large spatial variations of large positive and negative LHF differences with GSSTF2 to cancel and to produce smaller regional-mean differences. Our analyses suggest that the GSSTF2 latent heat flux

  15. Fractal analysis on Enceladus: a global ocean underneath the icy crust

    NASA Astrophysics Data System (ADS)

    Lucchetti, Alice; Pozzobon, Riccardo; Mazzarini, Francesco; Cremonese, Gabriele; Simioni, Emanuele; Massironi, Matteo

    2016-04-01

    Plumes of water have been observed erupting from Enceladus' south polar terrain providing direct evidence of a reservoir of liquid below the surface, that could be considered global or just a small body of water concentrated at its south pole. Gravity data collected during the spacecraft's several close flyby over the south polar region determined that the icy shell above the liquid ocean must be 30-40 km thick extending from the south pole up to 50°S (Iess et al. 2014). The hypothesis of a global ocean beneath the icy crust has been raised even in a recent paper of Thomas et al. (2015) thanks to the measurements of the very slight wobble that Enceladus displays as it orbits Saturn. In this work we support the hypothesis of the presence of an ocean layer using the fractal percolation theory. This method allowed us to estimate the icy shell thickness values in different regions of Enceladus from the south polar terrain up to the north pole. The spatial distribution of fractures on Enceladus has been analyzed in terms of their self-similar clustering and a two-point correlation method was used to measure the fractal dimension of the fractures population (Mazzarini, 2004, 2010). A self-similar clustering of fractures is characterized by a correlation coefficient with a size range defined by a lower and upper cut-off, that represent a mechanical discontinuity and the thickness of the fractured icy crust, thus connected to the liquid reservoir. We mapped the fractures on Enceladus surface based on April 2010 global mosaic from Cassini mission and applied the fractal method firstly to the south polar terrain finding indeed a fractal correlation of fractures and providing an ice shell thickness of ~40 km. Then, we analyzed fractures of four different regions around the equator and around the north pole inferring an overall ice shell thickness ranging from 35 to 45 km. Our results are in agreement with the gravity observations (Iess et al., 2014) and the mechanical models

  16. Global patterns of organic carbon export and sequestration in the ocean (Arne Richter Award for Outstanding Young Scientists)

    NASA Astrophysics Data System (ADS)

    Henson, S.; Sanders, R.; Madsen, E.; Le Moigne, F.; Quartly, G.

    2012-04-01

    A major term in the global carbon cycle is the ocean's biological carbon pump which is dominated by sinking of small organic particles from the surface ocean to its interior. Here we examine global patterns in particle export efficiency (PEeff), the proportion of primary production that is exported from the surface ocean, and transfer efficiency (Teff), the fraction of exported organic matter that reaches the deep ocean. This is achieved through extrapolating from in situ estimates of particulate organic carbon export to the global scale using satellite-derived data. Global scale estimates derived from satellite data show, in keeping with earlier studies, that PEeff is high at high latitudes and low at low latitudes, but that Teff is low at high latitudes and high at low latitudes. However, in contrast to the relationship observed for deep biomineral fluxes in previous studies, we find that Teff is strongly negatively correlated with opal export flux from the upper ocean, but uncorrelated with calcium carbonate export flux. We hypothesise that the underlying factor governing the spatial patterns observed in Teff is ecosystem function, specifically the degree of recycling occurring in the upper ocean, rather than the availability of calcium carbonate for ballasting. Finally, our estimate of global integrated carbon export is only 50% of previous estimates. The lack of consensus amongst different methodologies on the strength of the biological carbon pump emphasises that our knowledge of a major planetary carbon flux remains incomplete.

  17. NASA/GSFC Research Activities for the Global Ocean Carbon Cycle: A Prospectus for the 21st Century

    NASA Technical Reports Server (NTRS)

    Gregg, W. W.; Behrenfield, M. J.; Hoge, F. E.; Esaias, W. E.; Huang, N. E.; Long, S. R.; McClain, C. R.

    2000-01-01

    There are increasing concerns that anthropogenic inputs of carbon dioxide into the Earth system have the potential for climate change. In response to these concerns, the GSFC Laboratory for Hydrospheric Processes has formed the Ocean Carbon Science Team (OCST) to contribute to greater understanding of the global ocean carbon cycle. The overall goals of the OCST are to: 1) detect changes in biological components of the ocean carbon cycle through remote sensing of biooptical properties, 2) refine understanding of ocean carbon uptake and sequestration through application of basic research results, new satellite algorithms, and improved model parameterizations, 3) develop and implement new sensors providing critical missing environmental information related to the oceanic carbon cycle and the flux of CO2 across the air-sea interface. The specific objectives of the OCST are to: 1) establish a 20-year time series of ocean color, 2) develop new remote sensing technologies, 3) validate ocean remote sensing observations, 4) conduct ocean carbon cycle scientific investigations directly related to remote sensing data, emphasizing physiological, empirical and coupled physical/biological models, satellite algorithm development and improvement, and analysis of satellite data sets. These research and mission objectives are intended to improve our understanding of global ocean carbon cycling and contribute to national goals by maximizing the use of remote sensing data.

  18. An Assessment of the Effect of Sea-Surface Surfactants on Global Atmosphere-Ocean CO2 Flux

    NASA Astrophysics Data System (ADS)

    Tsai, W.; Liu, K.

    2001-05-01

    \\def\\ea{et al.} \\def\\CO2{CO2} \\def\\dpCO2{Δ pCO2} We assess the possible impact of the distribution of naturally occurring surfactants on the direct integration of the global atmosphere-ocean \\CO2 flux across the ocean surface. The global atmosphere-ocean \\CO2 flux is calculated using the monthly mean \\dpCO2 climatology compiled by Takahashi \\ea\\ [1997] as well as satellite wind speed and sea-surface temperature data. In the absence of any global map of surfactant coverage, and as it is known that phytoplankton exudates and degradation products are the major sources of marine surfactants, ocean primary productivity, which can be derived from the satellite-based estimate of chlorophyll concentration, is used as an indicator of the presence of surfactants. From the calculated results, it is found that suppression of the upward and downward \\CO2 fluxes by marine surfactants exhibits an asymmetric effect. For almost half of the year (between January and May), the presence of surfactants does not affect \\CO2 outgassing from global oceans. In contrast, throughout the entire year, the presence of surfactants suppresses \\CO2 absorption by the oceans. The average percent reduction of absorption flux by surfactants is about twice that of outgassing, which results in an overall decrease in the net global \\CO2 uptake by the oceans. The major reduction in absorption fluxes occurs in the northern Pacific and Atlantic (10oN to 70oN) in all seasons and in the Southern Ocean (south of 40oS) in austral spring and summer. However, the most significant decrease in outgassing fluxes occurs in the equatorial and southern Pacific Ocean (40oS to 10oN), particularly in the eastern equatorial and subtropical waters off the southern American coast, in the period of austral spring and summer.

  19. Iron-light colimitation in a global ocean biogeochemical model and the sensitivity of oceanic CO2 uptake to dust deposition

    NASA Astrophysics Data System (ADS)

    Nickelsen, L.; Oschlies, A.

    2012-12-01

    The iron hypothesis of glacial-interglacial cycles states that glacial increases in the deposition of dust enhanced the concentrations of the micronutrient iron in the ocean where it triggered phytoplankton growth and thus CO2 uptake. Indeed, iron fertilization experiments find that phytoplankton needs iron in particular for nitrate uptake, light harvesting, synthesis of chlorophyll and in the electron transport chain of photosynthesis. Previous global biogeochemical models used to extrapolate results from local culture and field experiments have suggested that the sensitivity of ocean biogeochemistry to changes in dust deposition is too low to account for the observed glacial-interglacial changes of atmospheric CO2 concentrations. Here we show that this sensitivity is increased significantly when iron-light colimitation, i.e. the impact of iron on light harvesting capabilities and chlorophyll synthesis, is explicitly considered in a global biogeochemical ocean model. Iron-light colimitation increases the shift of export production to higher latitudes at high dust deposition and amplifies iron limitation at low dust deposition. Our results suggest that iron fertilization by increased dust deposition may explain a substantially larger portion of the observed past CO2 variability than thought previously. Our results emphasize the role of iron as a key limiting nutrient for phytoplankton in the ocean, with a high potential for changes in oceanic iron supply affecting the global carbon cycle and climate.

  20. Long-Term Predictions of Global Climate Using the Ocean Conveyor

    SciTech Connect

    Ray, P.; Wilson, J.R.

    2003-01-01

    Many have attributed the Great Ocean Conveyor as a major driver of global climate change over millennia as well as a possible explanation for shorter (multidecadal) oscillations. The conveyor is thought to have a cycle time on the order of 1000 years, however recent research has suggested that it is much faster than previously believed (about 100 years). A faster conveyor leads to the possibility of the conveyor's role in even shorter oscillations such as the El Nino/Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO). The conveyor is primarily density driven. In this study the salty outflow of the Red Sea is used to predict its behavior ten years into the future. A successful model could lead to a long-term prediction (ten years) of El Ninos, Atlantic hurricane season intensity, as well as global temperature and precipitation patterns.

  1. US Air Force installation restoration program: Remedial investigation of former herbicide storage site at Johnston Island, Pacific Ocean

    SciTech Connect

    Not Available

    1988-09-01

    This report represents a synthesis and reformatting of six primary documents and other related materials on soils, ocean sediments, air, and biota investigations conducted at Johnston Island (JI), Pacific Ocean, to characterize contamination resulting from storage of 1.37 million gallons of Herbicide Orange (HO) from 1972 through 1977. The individual study components comprise the Remedial Investigation (RI) of the former HO storage site at JI. This report describes the procedures, results, and conclusions of the sampling and analysis programs conducted at JI. Samples of site soils, ocean sediments, airborne particulates, dust, sweepings, and aquatic organisms were collected and analyzed for HO-derived 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), and 2,3,7,8- tetrachlorodibenzo-p-dioxin (TCDD). Environmental media other than soils at the storage facility itself were found to be free of contamination or to contain very low contaminant concentrations. No contamination was found in ocean sediments, indicating possible dispersion of contaminants due to erosion. A few of the biological specimens collected were found to contain TCDD levels below the guidelines of 25 to 50 parts per trillion established by the US Food and Drug Administration; TCDD in all other biota samples was nondetectable. Analysis of samples of airborne particulates and of soils, dust, and sweepings from high-use and residential areas outside the boundaries of the former storage site indicated that there is little or no concern of adverse impacts from airborne transport and deposition of TCDD.

  2. Evidence for Global Biogeochemical Changes During the Toarcian Oceanic Anoxic Event

    NASA Astrophysics Data System (ADS)

    Them, T. R., II; Gill, B. C.; Gröcke, D. R.; Selby, D. S.; Martindale, R. C.; Caruthers, A. H.; Tulsky, E. T. T.

    2015-12-01

    The global versus regional nature of the Toarcian Oceanic Anoxic Event (T-OAE; ~183 million years ago) has been heavily debated over the course of the last decade. Several lines of geochemical evidence support a significant perturbation to the carbon cycle and redox-sensitive elemental cycles across this interval. It is thought that these represent feedbacks to the emplacement of the Karoo-Ferrar large igneous province. These include: elevated atmospheric pCO2, an enhanced greenhouse effect and hydrologic cycle leading to increased weathering rates, dissociation of biogenic methane clathrates, and widespread ocean anoxia. Despite evidence for these global phenomena, the overwhelming majority of stratigraphic successions studied are located in Europe. The global magnitude of these biogeochemical perturbations has been challenged, with some considering that this event was regional to Europe, and others suggesting that the carbon isotope excursion (CIE) itself is not a reliable stratigraphic marker. In order to test these competing hypotheses, we have generated a geochemical dataset to reconstruct paleoceanographic and paleoclimatological changes across the T-OAE from western North America. The Toarcian strata in western Alberta consist primarily of organic-rich calcareous siltstones and shales. These deposits represent ideal sedimentary facies to reconstruct environmental changes through the use of geochemical proxy data, especially those that use redox-sensitive transition metals. Ammonite biostratigraphy suggests a nearly continuous sequence from the late Pliensbachian to middle Toarcian. The organic carbon isotopes show the prominent negative CIE interpreted to relate to the release of isotopically depleted carbon at the onset of the T-OAE. Pyrite sulfur weight percentages increase across the CIE and remain elevated, and iron speciation data suggest the development of anoxic conditions. Initial osmium isotope compositions become more radiogenic during the CIE

  3. Quantification of A Tropical Missing Source From Ocean For The Carbonyl Sulfide Global Budget

    NASA Astrophysics Data System (ADS)

    Kuai, Le; Worden, John; Campbell, Elliott; Kulawik, Susan; Lee, Meemong; Montzka, Stephen; Berry, Joe; Baker, Ian; Denning, Scott; Kawa, Randy; Bian, Huisheng; Yung, Yuk

    2015-04-01

    Quantifying the carbonyl sulfide (OCS) surface fluxes contributes to the understanding of both sulfur cycle and carbon cycle. Although the major sources and sinks of OCS are well recognized, the uncertainties of individual types of the fluxes remain large. With the understanding of a large underestimate of ecosystem uptake, it suggests a large missing ocean source over tropical region to compensate the increased sink. However before AURA Tropospheric Emissions Spectrometer (TES) OCS data is released, no direct measurements have been taken to test this hypothesis. In this study, we performed a flux inversion to update the fluxes from TES OCS. Then we compared three experimental GEOS-Chem forward model runs driven by different fluxes based on TES inversion to HIPPO aircraft estimates in free troposphere and also to NOAA near surface observations. The TES data supports the hypothesis that a large source from tropical ocean is missing in the current OCS global budget and suggests that the source is even larger than that proposed in Berry et al., (2013). Consequently, it leads to a larger land uptake and increase the estimates of GPP. TES data also suggests the missing oceanic source is not symmetric about equator. It is strong and distributed further north of the equator (to 40°N) but weak and narrow south of the equator (to 20°S).

  4. Assessment of the hindcast, nowcast and forecast capabilities of the Mercator-Ocean high resolution ocean forecasting system in the Global and Atlantic and Mediterranean basins.

    NASA Astrophysics Data System (ADS)

    Lellouche, Jean-Michel; Tranchant, Benoît.; Bourdallé-Badie, Romain; Le Galloudec, Olivier; Greiner, Eric; Benkiran, Mounir; Derval, Corine; Testut, Charles-Emmanuel

    2010-05-01

    In the framework of the European project GMES/MyOcean, Mercator-Ocean has been designing a hierarchy of ocean analysis and forecasting systems based on numerical models of the ocean and data assimilation methods. Since April 2008, Mercator-Ocean runs an Atlantic and Mediterranean system at 1/12° between 20°S and 80°N. Since a few months, a global system, with the same horizontal and vertical resolution (50 levels on the vertical with a surface refinement), runs also in an operational mode. These two systems are eddy resolving. The ocean and sea ice models are based on the NEMO code. The data assimilation algorithm is a reduced order Kalman filter using 3D multivariate modal decomposition of the forecast error covariance. The system assimilates conjointly altimeter data, SST and in situ observations (temperature and salinity profiles, including ARGO data) in order to provide the initial conditions required for numerical ocean prediction. The main characteristics of the assimilation system are (i) the background error covariances calculated from a free oceanic simulation, (ii) the adaptive error variance, (iii) the use of the localization technique and (iv) the use of the IAU (Incremental Analysis Update) procedure where analysis increments are inserted at every time step over the same period as the data assimilation window. The real time operation of these systems produce each week realistic 3-dimensional oceanic conditions (temperature, salinity, currents,…) two weeks back in time (hindcast and nowcast) and a one or two weeks forecast, driven at the surface by atmospheric conditions from the European Center for Medium Range Weather Forecast (ECMWF). Moreover, the Atlantic and Mediterranean system is operated daily to produce 7 days ocean forecasts with daily updates of the ECMWF atmospheric forcing. A new version of the regional system is planned to replace soon the actual one with many improvements concerning the ocean model and the assimilation scheme

  5. A statistical gap-filling method to interpolate global monthly surface ocean carbon dioxide data

    NASA Astrophysics Data System (ADS)

    Jones, Steve D.; Le Quéré, Corinne; Rödenbeck, Christian; Manning, Andrew C.; Olsen, Are

    2015-12-01

    We have developed a statistical gap-filling method adapted to the specific coverage and properties of observed fugacity of surface ocean CO2 (fCO2). We have used this method to interpolate the Surface Ocean CO2 Atlas (SOCAT) v2 database on a 2.5°×2.5° global grid (south of 70°N) for 1985-2011 at monthly resolution. The method combines a spatial interpolation based on a "radius of influence" to determine nearby similar fCO2 values with temporal harmonic and cubic spline curve-fitting, and also fits long-term trends and seasonal cycles. Interannual variability is established using deviations of observations from the fitted trends and seasonal cycles. An uncertainty is computed for all interpolated values based on the spatial and temporal range of the interpolation. Tests of the method using model data show that it performs as well as or better than previous regional interpolation methods, but in addition it provides a near-global and interannual coverage.

  6. Seasonal and Inter-Annual Changes in the Distribution of Dominant Phytoplancton Groups in the Global Ocean

    NASA Astrophysics Data System (ADS)

    Severine, A.; Cyril, M.; Yves, D.; Laurent, B.; Hubert, L.

    2006-12-01

    The fate of fixed organic carbon in the ocean strongly varies with the phytoplankton group that makes photosynthesis. The monitoring of phytoplankton groups in the global ocean is thus of primary importance to evaluate and improve ocean carbon models. A new method (PHYSAT; Alvain et al., 2005) enables to distinguish between four different groups from space using SeaWiFS ocean color measurements. In addition to these four initial phytoplankton groups, which are diatoms, Prochlorococcus, Synecochoccus and haptophytes, we show that PHYSAT is also capable of identifying blooms of phaeocystis and coccolithophorids. Daily global SeaWiFS level-3 data from September 1997 to December 2004 were processed using PHYSAT. We present here the first monthly mean global climatology of the dominant phytoplankton groups. The seasonal cycle is discussed, with particular emphasis on the succession of phytoplankton groups during the North Atlantic spring bloom and on the coexistence of large phaeocystis and diatoms blooms during winter in the Austral Ocean. We also present the inter-annual variability for the 1998-2004 period. The contribution of diatoms to the total chlorophyll is highly variable (up to a factor of two) from one year to the other in both Atlantic and Austral Oceans, suggesting a significant variability in organic carbon export by diatoms in these regions. On the opposite, the phaeocystis contribution is less variable in the Austral Ocean.

  7. Global Ocean Reanalysis Simulations at Mercator Océan GLORYS1: the Argo years 2002-2008

    NASA Astrophysics Data System (ADS)

    Drevillon, M.; Parent, L.; Ferry, N.; Greiner, E.; Barnier, B.

    2009-12-01

    Since a decade ago, Mercator Océan develops and operates different ocean forecasting systems based on OGCM models and advanced data assimilation schemes using in situ and remotely sensed data. In the framework of the European GMES MyOcean project (FP7, 2009-2011), Mercator Océan will become a main contributor for the delivery of regular and systematic information to intermediate users & downstream service provider. Conjointly to this operational activity, the generation of global reanalysis simulations is a growing priority to satisfy scientist demands for climate studies. During this presentation, we will expose the results of the first global eddy-permitting (1/4°) ocean reanalysis simulation performed by Mercator Océan. It covers the 2002-2008 time period, which benefits from the ARGO float measurements. This significant improvement of the Global Ocean Observing System tends to indicate that the last decade is the primary test bed period for the development and the validation of any ocean reanalysis system. The “reanalysis system” is based on the current operational global ocean forecasting system, available since April 2008: the ocean and sea ice model NEMO is coupled with the SAM2 (Système d'Assimilation Mercator V2) data assimilation system, a reduced order extended Kalman filter with the capability to manage various and high number of observations and specially designed for expensive configurations. Dedicated altimetry database (from CLS) and in situ database (from CORIOLIS data center / Ifremer) have been used for the integration of this reanalysis simulation and the temporal continuity is assured by the IAU (Incremental Analysis Updates) method. An overall assessment of this reanalysis simulation will be given, with its strengths, its limitations and its necessary update in order to obtain a better depiction of the ocean state along the 2000's or the Altimetry years (1992-today). contact:lparent@mercator-ocean.fr

  8. Linking nutrient loading and oxygen in the coastal ocean: A new global scale model

    NASA Astrophysics Data System (ADS)

    Reed, Daniel C.; Harrison, John A.

    2016-03-01

    Recent decades have witnessed an exponential spread of low-oxygen regions in the coastal ocean due at least in-part to enhanced terrestrial nutrient inputs. As oxygen deprivation is a major stressor on marine ecosystems, there is a great need to quantitatively link shifts in nutrient loading with changes in oxygen concentrations. To this end, we have developed and here describe, evaluate, and apply the Coastal Ocean Oxygen Linked to Benthic Exchange And Nutrient Supply (COOLBEANS) model, a first-of-its-kind, spatially explicit (with 152 coastal segments) model, global model of coastal oxygen and nutrient dynamics. In COOLBEANS, benthic oxygen demand (BOD) is calculated using empirical models for aerobic respiration, iron reduction, and sulfate reduction, while oxygen supply is represented by a simple parameterization of exchange between surface and bottom waters. A nutrient cycling component translates shifts in riverine nutrient inputs into changes in organic matter delivery to sediments and, ultimately, oxygen uptake. Modeled BOD reproduces observations reasonably well (Nash-Sutcliffe efficiency = 0.71), and estimates of exchange between surface and bottom waters correlate with stratification. The model examines sensitivity of bottom water oxygen to changes in nutrient inputs and vertical exchange between surface and bottom waters, highlighting the importance of this vertical exchange in defining the susceptibility of a system to oxygen depletion. These sensitivities along with estimated maximum hypoxic areas that are supported by present day nutrient loads are consistent with existing hypoxic regions. Sensitivities are put into context by applying historic changes in nitrogen loading observed in the Gulf of Mexico to the global coastal ocean, demonstrating that such loads would drive many systems anoxic or even sulfidic.

  9. Lithium contents and isotopic compositions of ferromanganese deposits from the global ocean

    USGS Publications Warehouse

    Chan, L.-H.; Hein, J.R.

    2007-01-01

    To test the feasibility of using lithium isotopes in marine ferromanganese deposits as an indicator of paleoceanographic conditions and seawater composition, we analyzed samples from a variety of tectonic environments in the global ocean. Hydrogenetic, hydrothermal, mixed hydrogenetic–hydrothermal, and hydrogenetic–diagenetic samples were subjected to a two-step leaching and dissolution procedure to extract first the loosely bound Li and then the more tightly bound Li in the Mn oxide and Fe oxyhydroxide. Total leachable Li contents vary from 2 by coulombic force. Hence, the abundant Li in hydrothermal deposits is mainly associated with the dominant phase, MnO2. The surface of amorphous FeOOH holds a slightly positive charge and attracts little Li, as demonstrated by data for hydrothermal Fe oxyhydroxide. Loosely sorbed Li in both hydrogenetic crusts and hydrothermal deposits exhibit Li isotopic compositions that resemble that of modern seawater. We infer that the hydrothermally derived Li scavenged onto the surface of MnO2 freely exchanged with ambient seawater, thereby losing its original isotopic signature. Li in the tightly bound sites is always isotopically lighter than that in the loosely bound fraction, suggesting that the isotopic fractionation occurred during formation of chemical bonds in the oxide and oxyhydroxide structures. Sr isotopes also show evidence of re-equilibration with seawater after deposition. Because of their mobility, Li and Sr in the ferromanganese crusts do not faithfully record secular variations in the isotopic compositions of seawater. However, Li content can be a useful proxy for the hydrothermal history of ocean basins. Based on the Li concentrations of the globally distributed hydrogenetic and hydrothermal samples, we estimate a scavenging flux of Li that is insignificant compared to the hydrothermal flux and river input to the ocean.

  10. A new global interior ocean mapped climatology: the 1° × 1° GLODAP version 2

    NASA Astrophysics Data System (ADS)

    Lauvset, Siv K.; Key, Robert M.; Olsen, Are; van Heuven, Steven; Velo, Anton; Lin, Xiaohua; Schirnick, Carsten; Kozyr, Alex; Tanhua, Toste; Hoppema, Mario; Jutterström, Sara; Steinfeldt, Reiner; Jeansson, Emil; Ishii, Masao; Perez, Fiz F.; Suzuki, Toru; Watelet, Sylvain

    2016-08-01

    We present a mapped climatology (GLODAPv2.2016b) of ocean biogeochemical variables based on the new GLODAP version 2 data product (Olsen et al., 2016; Key et al., 2015), which covers all ocean basins over the years 1972 to 2013. The quality-controlled and internally consistent GLODAPv2 was used to create global 1° × 1° mapped climatologies of salinity, temperature, oxygen, nitrate, phosphate, silicate, total dissolved inorganic carbon (TCO2), total alkalinity (TAlk), pH, and CaCO3 saturation states using the Data-Interpolating Variational Analysis (DIVA) mapping method. Improving on maps based on an earlier but similar dataset, GLODAPv1.1, this climatology also covers the Arctic Ocean. Climatologies were created for 33 standard depth surfaces. The conceivably confounding temporal trends in TCO2 and pH due to anthropogenic influence were removed prior to mapping by normalizing these data to the year 2002 using first-order calculations of anthropogenic carbon accumulation rates. We additionally provide maps of accumulated anthropogenic carbon in the year 2002 and of preindustrial TCO2. For all parameters, all data from the full 1972-2013 period were used, including data that did not receive full secondary quality control. The GLODAPv2.2016b global 1° × 1° mapped climatologies, including error fields and ancillary information, are available at the GLODAPv2 web page at the Carbon Dioxide Information Analysis Center (CDIAC; doi:10.3334/CDIAC/OTG.NDP093_GLODAPv2).

  11. A global planktic foraminifer census data set for the Pliocene ocean.

    PubMed

    Dowsett, Harry; Robinson, Marci; Foley, Kevin

    2015-01-01

    This article presents data derived by the USGS Pliocene Research, Interpretation and Synoptic Mapping (PRISM) Project. PRISM has generated planktic foraminifer census data from core sites and outcrops around the globe since 1988. These data form the basis of a number of paleoceanographic reconstructions focused on the mid-Piacenzian Warm Period (3.264 to 3.025 million years ago). Data are presented as counts of individuals within 64 taxonomic categories for each locality. We describe sample acquisition and processing, age dating, taxonomy and archival storage of material. These data provide a unique, stratigraphically focused opportunity to assess the effects of global warming on marine plankton. PMID:26645473

  12. A global planktic foraminifer census data set for the Pliocene ocean

    PubMed Central

    Dowsett, Harry; Robinson, Marci; Foley, Kevin

    2015-01-01

    This article presents data derived by the USGS Pliocene Research, Interpretation and Synoptic Mapping (PRISM) Project. PRISM has generated planktic foraminifer census data from core sites and outcrops around the globe since 1988. These data form the basis of a number of paleoceanographic reconstructions focused on the mid-Piacenzian Warm Period (3.264 to 3.025 million years ago). Data are presented as counts of individuals within 64 taxonomic categories for each locality. We describe sample acquisition and processing, age dating, taxonomy and archival storage of material. These data provide a unique, stratigraphically focused opportunity to assess the effects of global warming on marine plankton. PMID:26645473

  13. A global planktic foraminifer census data set for the Pliocene ocean

    USGS Publications Warehouse

    Dowsett, Harry J.; Robinson, Marci M.; Foley, Kevin M.

    2016-01-01

    This article presents data derived by the USGS Pliocene Research, Interpretation and Synoptic Mapping (PRISM) Project. PRISM has generated planktic foraminifer census data from core sites and outcrops around the globe since 1988. These data form the basis of a number of paleoceanographic reconstructions focused on the mid-Piacenzian Warm Period (3.264 to 3.025 million years ago). Data are presented as counts of individuals within 64 taxonomic categories for each locality. We describe sample acquisition and processing, age dating, taxonomy and archival storage of material. These data provide a unique, stratigraphically focused opportunity to assess the effects of global warming on marine plankton.

  14. Extensive genetic diversity and endemism across the global range of the oceanic copepod Pleuromamma abdominalis

    NASA Astrophysics Data System (ADS)

    Hirai, Junya; Tsuda, Atsushi; Goetze, Erica

    2015-11-01

    Many oceanic zooplankton species have been described as cosmopolitan in distribution; however, recent molecular work has detected species complexity with highly divergent genetic lineages within several of these taxa. To further resolve the species complexity within these ecologically-important and widespread species, we performed both molecular and morphological analyses of the oceanic copepod Pleuromamma abdominalis using a comprehensive collection of material from 944 individuals collected at 46 sites across the global ocean. Phylogenetic analyses of mitochondrial cytochrome oxidase subunit I (mtCOI) sequences detected eighteen divergent evolutionary lineages within P. abdominalis, with an additional four singleton specimens that were also genetically divergent. Two phylogenetically distinct groups, PLAB1 and PLAB2, were supported by concordant sequence variation in the nuclear large subunit ribosomal RNA gene (nLSU). Within PLAB1, two mtCOI clades, 1a-1 and 1b-1 were observed, and each clade contained geographically distinct sub-clades 1a-2 and 1b-2. PLAB2 was composed of sixteen well-supported mtCOI clades (2a-2p) as well as four singletons. High genetic divergence among the mtCOI lineages within both PLAB1 and PLAB2, ranging between 9.2-11.2% and 4.3-18.9% K2P distances respectively, suggests the presence of additional species within these groups. Significant differences were observed in the presence and shape of antennule spines of adult females between sympatric clades with genetic distances greater than 5.7-7.0% (K2P). The biogeographic distributions of mtCOI clades indicated greater specialization to particular oceanographic provinces than observed in the nominal species P. abdominalis, with mtCOI clades ranging from antitropical in subtropical waters of all three ocean basins (Atlantic, Pacific and Indian; clade 1b-1 and 2a) to taxa that are endemic to a particular ocean region, for example restricted to equatorial waters of the Atlantic Ocean (clade 1b

  15. A compilation of global bio-optical in situ data for ocean-colour satellite applications

    NASA Astrophysics Data System (ADS)

    Valente, André; Sathyendranath, Shubha; Brotas, Vanda; Groom, Steve; Grant, Michael; Taberner, Malcolm; Antoine, David; Arnone, Robert; Balch, William M.; Barker, Kathryn; Barlow, Ray; Bélanger, Simon; Berthon, Jean-François; Beşiktepe, Şükrü; Brando, Vittorio; Canuti, Elisabetta; Chavez, Francisco; Claustre, Hervé; Crout, Richard; Frouin, Robert; García-Soto, Carlos; Gibb, Stuart W.; Gould, Richard; Hooker, Stanford; Kahru, Mati; Klein, Holger; Kratzer, Susanne; Loisel, Hubert; McKee, David; Mitchell, Brian G.; Moisan, Tiffany; Muller-Karger, Frank; O'Dowd, Leonie; Ondrusek, Michael; Poulton, Alex J.; Repecaud, Michel; Smyth, Timothy; Sosik, Heidi M.; Twardowski, Michael; Voss, Kenneth; Werdell, Jeremy; Wernand, Marcel; Zibordi, Giuseppe

    2016-06-01

    A compiled set of in situ data is important to evaluate the quality of ocean-colour satellite-data records. Here we describe the data compiled for the validation of the ocean-colour products from the ESA Ocean Colour Climate Change Initiative (OC-CCI). The data were acquired from several sources (MOBY, BOUSSOLE, AERONET-OC, SeaBASS, NOMAD, MERMAID, AMT, ICES, HOT, GeP&CO), span between 1997 and 2012, and have a global distribution. Observations of the following variables were compiled: spectral remote-sensing reflectances, concentrations of chlorophyll a, spectral inherent optical properties and spectral diffuse attenuation coefficients. The data were from multi-project archives acquired via the open internet services or from individual projects, acquired directly from data providers. Methodologies were implemented for homogenisation, quality control and merging of all data. No changes were made to the original data, other than averaging of observations that were close in time and space, elimination of some points after quality control and conversion to a standard format. The final result is a merged table designed for validation of satellite-derived ocean-colour products and available in text format. Metadata of each in situ measurement (original source, cruise or experiment, principal investigator) were preserved throughout the work and made available in the final table. Using all the data in a validation exercise increases the number of matchups and enhances the representativeness of different marine regimes. By making available the metadata, it is also possible to analyse each set of data separately. The compiled data are available at doi:10.1594/PANGAEA.854832 (Valente et al., 2015).

  16. Atmospheric dry deposition of persistent organic pollutants to the Atlantic and inferences for the global oceans.

    PubMed

    Jurado, Elena; Jaward, Foday M; Lohmann, Rainer; Jones, Kevin C; Simó, Rafel; Dachs, Jordi

    2004-11-01

    Atmospheric deposition to the oceans is a key process affecting the global dynamics and sinks of persistent organic pollutants (POPs). A new methodology that combines aerosol remote sensing measurements with measured POP aerosol-phase concentrations is presented to derive dry particulate depositional fluxes of POPs to the oceans. These fluxes are compared with those due to diffusive air-water exchange. For all polychlorinated biphenyl (PCB) congeners and lower chlorinated dibenzo-p-dioxins and furans (PCDD/Fs), air-water exchange dominates the dry deposition mechanism. However, this tendency reverses in some areas, such as in marine aerosol influenced areas and dust outflow regions, consistent with the important variability encountered for the depositional fluxes. Seasonal variability is mainly found in mid-high latitudes, due to the important influence of wind speed enhancing dry deposition fluxes and temperature as a driver of the gas-particle partitioning of POPs. The average dry aerosol deposition flux of sigmaPCBs and sigmaPCDD/Fs to the Atlantic Ocean is calculated to be in the order of 66 ng m(-2) yr(-1) and 9 ng m(-2)yr(-1) respectively. The total dry aerosol deposition of sigmaPCBs and sigmaPCDD/Fs to the Atlantic Ocean is estimated to be 2200 kg yr(-1) and 500 kg yr(-1), respectively, while the net air-water exchange is higher, 22000 kg sigmaPCBs yr(-1) for PCBs and 1300 kg sigmaPCDD/Fs yr(-1). Furthermore, it is suggested that marine aerosol plays an important role in scavenging atmospheric contaminants. PMID:15575265

  17. Using Three Global Climate Indices to Forecast Hurricane Activity in the Pacific and Atlantic Oceans

    NASA Astrophysics Data System (ADS)

    Giovannettone, J. P.

    2014-12-01

    Quantitative relationships between global climate indices and hurricane activity in the Pacific and Atlantic Oceans have not been widely studied. A few studies have explored qualitative relationships between hurricane activity and such climate indices as the North Atlantic Oscillation and sea-surface temperatures, among others. The current work presents the most comprehensive analysis of the potential relationships between 39 different climate indices and hurricane activity using regression and frequency analysis. Attempts are made to develop statistical relationships between any one of these indices and hurricane activity in the eastern and western Pacific as well as the Atlantic Oceans. There were three climate indices, one per region, showing significantly higher correlation in each region. They were the ENSO Precipitation Index (EPI) in the western Pacific, the Atlantic Multi-decadal Oscillation (AMO) in the eastern Pacific, and the Atlantic Meridional Mode (AMM) in the Atlantic. The linear relationships between each index and hurricane numbers resulted in Pearson-R values of near 0.65 or greater. In addition, the Madden-Julian Oscillation showed some correlation with hurricane activity in each region and therefore was included in the analysis. Several important results were found during these analyses. For instance, the relationship between the AMM index and hurricane numbers in the Atlantic Ocean revealed that the average July - October AMM index was greater than -0.5 within a range of -5.0 to 5.0 for years within the last 70 years when the number of hurricanes during that same period was greater than 7. It is also shown that the number of hurricanes expected to be exceeded or not exceeded at frequencies of 50- to 100-years, for example, varies substantially depending on the range of AMM index values being analyzed. Similar results are shown for the eastern and western Pacific Ocean as well. Such relationships provide forecasters with a simple tool using only

  18. Decadal trends in global pelagic ocean chlorophyll: A new assessment integrating multiple satellites, in situ data, and models

    PubMed Central

    Gregg, Watson W; Rousseaux, Cécile S

    2014-01-01

    Quantifying change in ocean biology using satellites is a major scientific objective. We document trends globally for the period 1998–2012 by integrating three diverse methodologies: ocean color data from multiple satellites, bias correction methods based on in situ data, and data assimilation to provide a consistent and complete global representation free of sampling biases. The results indicated no significant trend in global pelagic ocean chlorophyll over the 15 year data record. These results were consistent with previous findings that were based on the first 6 years and first 10 years of the SeaWiFS mission. However, all of the Northern Hemisphere basins (north of 10° latitude), as well as the Equatorial Indian basin, exhibited significant declines in chlorophyll. Trend maps showed the local trends and their change in percent per year. These trend maps were compared with several other previous efforts using only a single sensor (SeaWiFS) and more limited time series, showing remarkable consistency. These results suggested the present effort provides a path forward to quantifying global ocean trends using multiple satellite missions, which is essential if we are to understand the state, variability, and possible changes in the global oceans over longer time scales. PMID:26213675

  19. Sulfur isotopes track the global extent and dynamics of euxinia during Cretaceous Oceanic Anoxic Event 2

    PubMed Central

    Owens, Jeremy D.; Gill, Benjamin C.; Jenkyns, Hugh C.; Bates, Steven M.; Severmann, Silke; Kuypers, Marcel M. M.; Woodfine, Richard G.; Lyons, Timothy W.

    2013-01-01

    The Mesozoic Era is characterized by numerous oceanic anoxic events (OAEs) that are diagnostically expressed by widespread marine organic-carbon burial and coeval carbon-isotope excursions. Here we present coupled high-resolution carbon- and sulfur-isotope data from four European OAE 2 sections spanning the Cenomanian–Turonian boundary that show roughly parallel positive excursions. Significantly, however, the interval of peak magnitude for carbon isotopes precedes that of sulfur isotopes with an estimated offset of a few hundred thousand years. Based on geochemical box modeling of organic-carbon and pyrite burial, the sulfur-isotope excursion can be generated by transiently increasing the marine burial rate of pyrite precipitated under euxinic (i.e., anoxic and sulfidic) water-column conditions. To replicate the observed isotopic offset, the model requires that enhanced levels of organic-carbon and pyrite burial continued a few hundred thousand years after peak organic-carbon burial, but that their isotope records responded differently due to dramatically different residence times for dissolved inorganic carbon and sulfate in seawater. The significant inference is that euxinia persisted post-OAE, but with its global extent dwindling over this time period. The model further suggests that only ∼5% of the global seafloor area was overlain by euxinic bottom waters during OAE 2. Although this figure is ∼30× greater than the small euxinic fraction present today (∼0.15%), the result challenges previous suggestions that one of the best-documented OAEs was defined by globally pervasive euxinic deep waters. Our results place important controls instead on local conditions and point to the difficulty in sustaining whole-ocean euxinia. PMID:24170863

  20. Tidal hydrodynamics of the Hudson Bay and its impact in the global ocean tide

    NASA Astrophysics Data System (ADS)

    Chevalier, Laetitia; Lyard, Florent; Greenberg, David; Soufflet, Yves

    2013-04-01

    In 2012, the global ocean tides atlas FES has been updated with the financial support of the French Space Agency (CNES). The examination of the tidal energy budget from the hydrodynamic solution has demonstrated the critical impact of the tidal dissipation in Hudson Bay (over-estimated in FES2012) for the accuracy of global solution especially in the Atlantic. To further explore this issue, a regional study of the tidal hydrodynamics of the Hudson Bay has been carried out with a numerical model (the finite elements model T-UGOm) and observations (altimetry-derrived and in situ data). This study aims to answer questions about the role of tidal dissipation in the Hudson system in relation with the global ocean tides. Among the numerical parameters, the two most critical in terms of tidal dissipation are the bathymetry and the friction coefficient. A sensitivity study has been carried out using the standard bathymetry data set (GEBCO, ETOPO, Smith and Sandwell) and prescribing regionally varying friction coefficients. In addition, a new Hudson bay bathymetry has been reconstructed from ship tracks sounding and other direct depth measurements. Despite these improvements, mostly due to the reconstructed bathymetry, the total energy dissipated by the bottom friction in the Hudson Bay is still significantly too large. The reason for that could be the large remaining uncertainties in the bathymetry especially in Fox Basin. Another reason could be the limitation of 2D modelling in accurately reproducing the energy dissipation in a resonant system such as the Hudson Bay, especially the effect of vertical momentum diffusion in the water column. Consequently, a 3D configuration has been set up to extend our sensitivity study. The results of this work will be presented, concentrating particularly on the energy budget.

  1. Sulfur isotopes track the global extent and dynamics of euxinia during Cretaceous Oceanic Anoxic Event 2.

    PubMed

    Owens, Jeremy D; Gill, Benjamin C; Jenkyns, Hugh C; Bates, Steven M; Severmann, Silke; Kuypers, Marcel M M; Woodfine, Richard G; Lyons, Timothy W

    2013-11-12

    The Mesozoic Era is characterized by numerous oceanic anoxic events (OAEs) that are diagnostically expressed by widespread marine organic-carbon burial and coeval carbon-isotope excursions. Here we present coupled high-resolution carbon- and sulfur-isotope data from four European OAE 2 sections spanning the Cenomanian-Turonian boundary that show roughly parallel positive excursions. Significantly, however, the interval of peak magnitude for carbon isotopes precedes that of sulfur isotopes with an estimated offset of a few hundred thousand years. Based on geochemical box modeling of organic-carbon and pyrite burial, the sulfur-isotope excursion can be generated by transiently increasing the marine burial rate of pyrite precipitated under euxinic (i.e., anoxic and sulfidic) water-column conditions. To replicate the observed isotopic offset, the model requires that enhanced levels of organic-carbon and pyrite burial continued a few hundred thousand years after peak organic-carbon burial, but that their isotope records responded differently due to dramatically different residence times for dissolved inorganic carbon and sulfate in seawater. The significant inference is that euxinia persisted post-OAE, but with its global extent dwindling over this time period. The model further suggests that only ~5% of the global seafloor area was overlain by euxinic bottom waters during OAE 2. Although this figure is ~30× greater than the small euxinic fraction present today (~0.15%), the result challenges previous suggestions that one of the best-documented OAEs was defined by globally pervasive euxinic deep waters. Our results place important controls instead on local conditions and point to the difficulty in sustaining whole-ocean euxinia. PMID:24170863

  2. OVOC (Oxygenated Volatile Organic Chemicals) in the Global Atmosphere: Atmospheric Budgets, Oceanic Concentrations, and Uncertainties

    NASA Technical Reports Server (NTRS)

    Singh, Hanwant B.

    2004-01-01

    Airborne measurements of oxygenated volatile organic chemicals (OVOC), OH free radicals, and tracers of pollution were performed over the Pacific during Winter/Spring of 2001. Large concentrations of OVOC are present in the global troposphere and are expected to play an important role in atmospheric chemistry. Their total abundance (SIGMAOVOC) was nearly twice that of non-methane hydrocarbons (SIGMAC2-C8 NMHC). Throughout the troposphere, the OH reactivity of OVOC is comparable to that of methane and far exceeds that of NHMC. A comparison of these data with western Pacific observations collected some seven years earlier (Feb.-March, 1994) did not reveal significant differences. Analysis of the relative enhancement of selected OVOC with respect to CH3Cl and CO in twelve plumes originating from fires and sampled in the free troposphere (3-11 km) is used to assess their primary and secondary emissions from biomass combustion. The composition of these plumes also indicates a large shift of reactive nitrogen into the PAN reservoir thereby limiting ozone formation. These data are combined with other observations and interpreted with the help of a global 3-D model to assess OVOC global sources and sinks. We further interpret atmospheric observations with the help of an air-sea exchange model io show that oceans can be both net sorces and sinks. An extremely large oceanic reservoir of OVOC, that exceeds the atmospheric reservoir by more than an order of magnitude, can be inferred to be present. We conclude that OVOC sources are extremely large (150-500 TgC y-1) but remain poorly quantified. In many cases, measured concentrations are uncertain and incompatible with our present knowledge of atmospheric chemistry. Results based on observations from several field studies and critical gaps will be discussed.

  3. Soluble dust as source of nutrients to the global ocean and the role of humans.

    NASA Astrophysics Data System (ADS)

    Kanakidou, Maria; Myriokefalitakis, Stelios; Nikolaou, Panagiota; Daskalakis, Nikos; Theodosi, Christina; Nenes, Athanassios; Tsigaridis, Kostas; Mihalopoulos, Nikos

    2015-04-01

    Atmospheric deposition of trace constituents, both of natural and anthropogenic origin, can act as a nutrient source into the open ocean and affect marine ecosystem functioning and subsequently the exchange of CO2 between the atmosphere and the global ocean. Dust is known as a major source of nutrients (Fe and P) into the atmosphere, but only a fraction of these nutrients is released in soluble form that can be assimilated by the ecosystems. Dust is also known to enhance N deposition by interacting with anthropogenic pollutants and neutralisation of part of the acidity of the atmosphere by crustal alkaline species. The link between the soluble iron (Fe) and phosphorus (P) atmospheric deposition and atmospheric acidity, as well as anthropogenic sources, is investigated. The global atmospheric Fe, P and N cycle are parameterized in the global 3-D chemical transport model TM4-ECPL. Both primary emissions of total and soluble Fe and P associated with dust and combustion processes are taken into account, as well as inorganic and organic N emissions. The impact of atmospheric acidity on nutrient solubility is parameterised based on experimental findings. The model results are evaluated by comparison with available observations. The impact of air-quality changes on soluble nutrient deposition is studied by performing sensitivity simulations using preindustrial, present and future emission scenarios. The response of the chemical composition of nutrient-containing aerosols to environmental changes is demonstrated and quantified. This work has been supported by ARISTEIA - PANOPLY grant co-financed by European Union (ESF) and Greek national funds NSRF.

  4. Marine biogenic aerosol sources simulated from below the global ocean-atmosphere interface

    NASA Astrophysics Data System (ADS)

    Elliott, S.; Burrows, S. M.; Cameron-Smith, P. J.; Deal, C.; Maltrud, M. E.; Ogunro, O. O.; Russell, L. M.; Wang, S.; Wingenter, O. W.

    2015-12-01

    Full understanding of biogenic aerosol emissions may require modeling of production, interconversion, phase changes and other processes influencing precursor distributions below the ocean surface. We describe a bottom-up, chemical oceanographic approach to the representation of marine sources now under development for Earth System Models in the U.S. Department of Energy. The motivation is to move beyond indirect bulk indicators such as chlorophyll or total dissolved organics. Dynamic mechanistic capabilities are sought for the relevant mixed layer materials and flux fields. The resulting fidelity and predictive capabilities may prove crucial during the era of global change. Reactive transport calculations are outlined for organosulfur, the suite of biomacromolecules, their degradation products plus both interphase or interfacial transitions. Volatile and polymeric substances are controlled on a compound by compound basis, driven by results from a global ecodynamics model of multiple phytotaxa and trophic levels. Surfactant behavior is considered simultaneously at the global bubble and atmospheric interfaces, and such two dimensional chemistry is extended beyond Langmuir monolayers to electrostatically supported films. Colloidal and gel sweeping-impaction by the wind-driven bubble field are considered as alternate means of vertical transport. At the top of the ocean within the microlayer, effects on sea spray number flux are estimated. Moving beyond aerosol emissions, our methods can also provide insight into the uncertainties traditionally inherent to sea-air gas transfer, since they are connected to macromolecular viscoelastics in the laminar barrier layer. We find that resolution of all these subsurface processes is possible at the level of the biogeographic marine province, including specialized treatments for the ice domain, sea ice edge and coastal regime.

  5. Climate change impacts on soil carbon storage in global croplands: 1901-2010

    NASA Astrophysics Data System (ADS)

    Ren, W.; Tian, H.

    2015-12-01

    New global data finds 12% of earth's surface in cropland at present. Croplands will take on the responsibility to support approximate 60% increase in food production by 2050 as FAO estimates. In addition to nutrient supply to plants, cropland soils also play a major source and sink of greenhouse gases regulating global climate system. It is a big challenge to understand how soils function under global changes, but it is also a great opportunity for agricultural sector to manage soils to assure sustainability of agroecosystems and mitigate climate change. Previous studies have attempted to investigate the impacts of different land uses and climates on cropland soil carbon storage. However, large uncertainty still exists in magnitude and spatiotemporal patterns of global cropland soil organic carbon, due to the lack of reliable environmental databases and relatively poorly understanding of multiple controlling factors involved climate change and land use etc. Here, we use a process-based agroecosystem model (DLEM-Ag) in combination with diverse data sources to quantify magnitude and tempo-spatial patterns of soil carbon storage in global croplands during 1901-2010. We also analyze the relative contributions of major environmental variables (climate change, land use and management etc.). Our results indicate that intensive land use management may hidden the vulnerability of cropland soils to climate change in some regions, which may greatly weaken soil carbon sequestration under future climate change.

  6. Modelling of global mass effects in hydrology, atmosphere and oceans on surface gravity

    NASA Astrophysics Data System (ADS)

    Mikolaj, M.; Meurers, B.; Güntner, A.

    2016-08-01

    We present a MatlabTM/Octave-based software tool mGlobe to compute the effect of atmospheric, continental water storage, and non-tidal ocean mass variations on surface gravity. These effects must be considered or reduced prior to any analysis of geophysical phenomena using observations of superconducting gravimeters. Contrary to the alternative providers, mGlobe allows the computation for an arbitrary location worldwide, supports a larger number of input models and offers more flexibility in terms of computation settings. The high number of supported models is important for assessment of model uncertainties. Discrepancies exceeding 75% were found. The continental water storage effect showed low sensitivity to spatial and temporal resolution. The deficient temporal resolution affects the non-tidal loading and atmospheric effects significantly. The same holds true for the influence of the spatial resolution on atmospheric effects. To compensate this effect, we introduce a site-specific correction factor based on differences between the real topography and model's orography.

  7. Using Green's Functions to initialize and adjust a global, eddying ocean biogeochemistry general circulation model

    NASA Astrophysics Data System (ADS)

    Brix, H.; Menemenlis, D.; Hill, C.; Dutkiewicz, S.; Jahn, O.; Wang, D.; Bowman, K.; Zhang, H.

    2015-11-01

    The NASA Carbon Monitoring System (CMS) Flux Project aims to attribute changes in the atmospheric accumulation of carbon dioxide to spatially resolved fluxes by utilizing the full suite of NASA data, models, and assimilation capabilities. For the oceanic part of this project, we introduce ECCO2-Darwin, a new ocean biogeochemistry general circulation model based on combining the following pre-existing components: (i) a full-depth, eddying, global-ocean configuration of the Massachusetts Institute of Technology general circulation model (MITgcm), (ii) an adjoint-method-based estimate of ocean circulation from the Estimating the Circulation and Climate of the Ocean, Phase II (ECCO2) project, (iii) the MIT ecosystem model "Darwin", and (iv) a marine carbon chemistry model. Air-sea gas exchange coefficients and initial conditions of dissolved inorganic carbon, alkalinity, and oxygen are adjusted using a Green's Functions approach in order to optimize modeled air-sea CO2 fluxes. Data constraints include observations of carbon dioxide partial pressure (pCO2) for 2009-2010, global air-sea CO2 flux estimates, and the seasonal cycle of the Takahashi et al. (2009) Atlas. The model sensitivity experiments (or Green's Functions) include simulations that start from different initial conditions as well as experiments that perturb air-sea gas exchange parameters and the ratio of particulate inorganic to organic carbon. The Green's Functions approach yields a linear combination of these sensitivity experiments that minimizes model-data differences. The resulting initial conditions and gas exchange coefficients are then used to integrate the ECCO2-Darwin model forward. Despite the small number (six) of control parameters, the adjusted simulation is significantly closer to the data constraints (37% cost function reduction, i.e., reduction in the model-data difference, relative to the baseline simulation) and to independent observations (e.g., alkalinity). The adjusted air-sea gas

  8. Constraints on hydrothermal heat flux through the oceanic lithosphere from global heat flow

    NASA Technical Reports Server (NTRS)

    Stein, Carol A.; Stein, Seth

    1994-01-01

    A significant discrepancy exists between the heat flow measured at the seafloor and the higher values predicted by thermal models of the cooling lithosphere. This discrepancy is generally interpreted as indicating that the upper oceanic crust is cooled significantly by hydrothermal circulation. The magnitude of this heat flow discrepancy is the primary datum used to estimate the volume of hydrothermal flow, and the variation in the discrepancy with lithospheric age is the primary constraint on how the hydrothermal flux is divided between near-ridge and off-ridge environments. The resulting estimates are important for investigation of both the thermal structure of the lithosphere and the chemistry of the oceans. We reevaluate the magnitude and age variation of the discrepancy using a global heat flow data set substantially larger than in earlier studies, and the GDHI (Global Depth and Heat Flow) model that better predicts the heat flow. We estimate that of the predicted global oceanic heat flux of 32 x 10(exp 12) W, 34% (11 x 10(exp 12) W) occurs by hydrothermal flow. Approximately 30% of the hydrothermal heat flux occurs in crust younger than 1 Ma, so the majority of this flux is off-ridge. These hydrothermal heat flux estimates are upper bounds, because heat flow measurements require sediment at the site and so are made preferentially at topographic lows, where heat flow may be depressed. Because the water temperature for the near-ridge flow exceeds that for the off-ridge flow, the near-ridge water flow will be even a smaller fraction of the total water flow. As a result, in estimating fluxes from geochemical data, use of the high water temperatures appropriate for the ridge axis may significantly overestimate the heat flux for an assumed water flux or underestimate the water flux for an assumed heat flux. Our data also permit improved estimates of the 'sealing' age, defined as the age where the observed heat flow approximately equals that predicted, suggesting

  9. Global land water storage change from GRACE over 2002-2009; Inference on sea level

    NASA Astrophysics Data System (ADS)

    Llovel, William; Becker, Mélanie; Cazenave, Anny; Crétaux, Jean-François; Ramillien, Guillaume

    2010-03-01

    Global change in land water storage and its effect on sea level is estimated over a 7-year time span (August 2002 to July 2009) using space gravimetry data from GRACE. The 33 World largest river basins are considered. We focus on the year-to-year variability and construct a total land water storage time series that we further express in equivalent sea level time series. The short-term trend in total water storage adjusted over this 7-year time span is positive and amounts to 80.6 ± 15.7 km 3/yr (net water storage excess). Most of the positive contribution arises from the Amazon and Siberian basins (Lena and Yenisei), followed by the Zambezi, Orinoco and Ob basins. The largest negative contributions (water deficit) come from the Mississippi, Ganges, Brahmaputra, Aral, Euphrates, Indus and Parana. Expressed in terms of equivalent sea level, total water volume change over 2002-2009 leads to a small negative contribution to sea level of -0.22 ± 0.05 mm/yr. The time series for each basin clearly show that year-to-year variability dominates so that the value estimated in this study cannot be considered as representative of a long-term trend. We also compare the interannual variability of total land water storage (removing the mean trend over the studied time span) with interannual variability in sea level (corrected for thermal expansion). A correlation of ˜0.6 is found. Phasing, in particular, is correct. Thus, at least part of the interannual variability of the global mean sea level can be attributed to land water storage fluctuations.

  10. A 15-year global biogeochemical reanalysis with ocean colour data assimilation

    NASA Astrophysics Data System (ADS)

    Ford, David; Barciela, Rosa

    2013-04-01

    A continuous global time-series of remotely sensed ocean colour observations is available from 1997 to the present day. However coverage is incomplete, and limited to the sea surface. Models are therefore required to provide full spatial coverage, and to investigate the relationships between physical and biological variables and the carbon cycle. Data assimilation can then be used to constrain models to fit the observations, thereby combining the advantages of both sources of information. As part of the European Space Agency's Climate Change Initiative (ESA-CCI), we assimilate chlorophyll concentration derived from ocean colour observations into a coupled physical-biogeochemical model. The data assimilation scheme (Hemmings et al., 2008, J. Mar. Res.; Ford et al., 2012, Ocean Sci.) uses the information from the observations to update all biological and carbon cycle state variables within the model. Global daily reanalyses have been produced, with and without assimilation of merged ocean colour data provided by GlobColour, for the period September 1997 to August 2012. The assimilation has been shown to significantly improve the model's representation of chlorophyll concentration, at the surface and at depth. Furthermore, there is evidence of improvement to the representation of pCO2, nutrients and zooplankton concentration compared to in situ observations. We use the results to quantify recent seasonal and inter-annual variability in variables including chlorophyll concentration, air-sea CO2 flux and alkalinity. In particular, we explore the impact of physical drivers such as the El Niño Southern Oscillation (ENSO) on the model's representation of chlorophyll and the carbon cycle, and the pros and cons of the model reanalyses compared to observation-based climatologies. Furthermore, we perform a comparison between the GlobColour product and an initial version of a new merged product being developed as part of the ESA-CCI. Equivalent year-long hindcasts are

  11. The release of dissolved actinium to the ocean: A global comparison of different end-members

    USGS Publications Warehouse

    Geibert, W.; Charette, M.; Kim, G.; Moore, W.S.; Street, J.; Young, M.; Paytan, A.

    2008-01-01

    The measurement of short-lived 223Ra often involves a second measurement for supported activities, which represents 227Ac in the sample. Here we exploit this fact, presenting a set of 284 values on the oceanic distribution of 227Ac, which was collected when analyzing water samples for short-lived radium isotopes by the radium delayed coincidence counting system. The present work compiles 227Ac data from coastal regions all over the northern hemisphere, including values from ground water, from estuaries and lagoons, and from marine end-members. Deep-sea samples from a continental slope off Puerto Rico and from an active vent site near Hawaii complete the overview of 227Ac near its potential sources. The average 227Ac activities of nearshore marine end-members range from 0.4??dpm m- 3 at the Gulf of Mexico to 3.0??dpm m- 3 in the coastal waters of the Korean Strait. In analogy to 228Ra, we find the extension of adjacent shelf regions to play a substantial role for 227Ac activities, although less pronounced than for radium, due to its weaker shelf source. Based on previously published values, we calculate an open ocean 227Ac inventory of 1.35 * 1018??dpm 227Acex in the ocean, which corresponds to 37??moles, or 8.4??kg. This implies a flux of 127??dpm m-2 y- 1 from the deep-sea floor. For the shelf regions, we obtain a global inventory of 227Ac of 4.5 * 1015??dpm, which cannot be converted directly into a flux value, as the regional loss term of 227Ac to the open ocean would have to be included. Ac has so far been considered to behave similarly to Ra in the marine environment, with the exception of a strong Ac source in the deep-sea due to 231Paex. Here, we present evidence of geochemical differences between Ac, which is retained in a warm vent system, and Ra, which is readily released [Moore, W.S., Ussler, W. and Paull, C.K., 2008-this issue. Short-lived radium isotopes in the Hawaiian margin: Evidence for large fluid fluxes through the Puna Ridge. Marine Chemistry

  12. Satellite-based global-ocean mass balance estimates of interannual variability and emerging trends in continental freshwater discharge

    PubMed Central

    Syed, Tajdarul H.; Famiglietti, James S.; Chambers, Don P.; Willis, Josh K.; Hilburn, Kyle

    2010-01-01

    Freshwater discharge from the continents is a key component of Earth’s water cycle that sustains human life and ecosystem health. Surprisingly, owing to a number of socioeconomic and political obstacles, a comprehensive global river discharge observing system does not yet exist. Here we use 13 years (1994–2006) of satellite precipitation, evaporation, and sea level data in an ocean mass balance to estimate freshwater discharge into the global ocean. Results indicate that global freshwater discharge averaged 36,055 km3/y for the study period while exhibiting significant interannual variability driven primarily by El Niño Southern Oscillation cycles. The method described here can ultimately be used to estimate long-term global discharge trends as the records of sea level rise and ocean temperature lengthen. For the relatively short 13-year period studied here, global discharge increased by 540 km3/y2, which was largely attributed to an increase of global-ocean evaporation (768 km3/y2). Sustained growth of these flux rates into long-term trends would provide evidence for increasing intensity of the hydrologic cycle. PMID:20921364

  13. Satellite-based global-ocean mass balance estimates of interannual variability and emerging trends in continental freshwater discharge.

    PubMed

    Syed, Tajdarul H; Famiglietti, James S; Chambers, Don P; Willis, Josh K; Hilburn, Kyle

    2010-10-19

    Freshwater discharge from the continents is a key component of Earth's water cycle that sustains human life and ecosystem health. Surprisingly, owing to a number of socioeconomic and political obstacles, a comprehensive global river discharge observing system does not yet exist. Here we use 13 years (1994-2006) of satellite precipitation, evaporation, and sea level data in an ocean mass balance to estimate freshwater discharge into the global ocean. Results indicate that global freshwater discharge averaged 36,055 km(3)/y for the study period while exhibiting significant interannual variability driven primarily by El Niño Southern Oscillation cycles. The method described here can ultimately be used to estimate long-term global discharge trends as the records of sea level rise and ocean temperature lengthen. For the relatively short 13-year period studied here, global discharge increased by 540 km(3)/y(2), which was largely attributed to an increase of global-ocean evaporation (768 km(3)/y(2)). Sustained growth of these flux rates into long-term trends would provide evidence for increasing intensity of the hydrologic cycle. PMID:20921364

  14. Global Ocean Reanalysis Simulations at Mercator Océan GLORYS1: the Argo years 2002-2008

    NASA Astrophysics Data System (ADS)

    Parent, L.; Ferry, N.; Barnier, B.; Drevillon, M.; Greiner, E.

    2009-04-01

    Since a decade ago, Mercator Océan develops and operates different ocean forecasting systems based on OGCM models and advanced data assimilation schemes using in situ and remotely sensed data. In the framework of the European GMES MyOcean project (FP7, 2009-2011), Mercator Océan will become a main contributor for the delivery of regular and systematic information to intermediate users & downstream service provider. Conjointly to this operational activity, the generation of global reanalysis simulations is a growing priority to satisfy scientist demands for climate studies. During this presentation, we will expose the results of the first global eddy-permitting (1/4°) ocean reanalysis simulation performed by Mercator Océan. It covers the 2002-2008 time period, which benefits from the ARGO float measurements. This significant improvement of the Global Ocean Observing System tends to indicate that the last decade is the primary test bed period for the development and the validation of any ocean reanalysis system. The "reanalysis system" is based on the current operational global ocean forecasting system, available since April 2008: the ocean and sea ice model NEMO is coupled with the SAM2 (Système d'Assimilation Mercator V2) data assimilation system, a reduced order extended Kalman filter wi