North Atlantic forcing of tropical Indian Ocean climate.

PubMed

Mohtadi, Mahyar; Prange, Matthias; Oppo, Delia W; De Pol-Holz, Ricardo; Merkel, Ute; Zhang, Xiao; Steinke, Stephan; Lückge, Andreas

2014-05-01

The response of the tropical climate in the Indian Ocean realm to abrupt climate change events in the North Atlantic Ocean is contentious. Repositioning of the intertropical convergence zone is thought to have been responsible for changes in tropical hydroclimate during North Atlantic cold spells, but the dearth of high-resolution records outside the monsoon realm in the Indian Ocean precludes a full understanding of this remote relationship and its underlying mechanisms. Here we show that slowdowns of the Atlantic meridional overturning circulation during Heinrich stadials and the Younger Dryas stadial affected the tropical Indian Ocean hydroclimate through changes to the Hadley circulation including a southward shift in the rising branch (the intertropical convergence zone) and an overall weakening over the southern Indian Ocean. Our results are based on new, high-resolution sea surface temperature and seawater oxygen isotope records of well-dated sedimentary archives from the tropical eastern Indian Ocean for the past 45,000 years, combined with climate model simulations of Atlantic circulation slowdown under Marine Isotope Stages 2 and 3 boundary conditions. Similar conditions in the east and west of the basin rule out a zonal dipole structure as the dominant forcing of the tropical Indian Ocean hydroclimate of millennial-scale events. Results from our simulations and proxy data suggest dry conditions in the northern Indian Ocean realm and wet and warm conditions in the southern realm during North Atlantic cold spells.

CARINA alkalinity data in the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Velo, A.; Perez, F. F.; Brown, P.; Tanhua, T.; Schuster, U.; Key, R. M.

2009-08-01

Data on carbon and carbon-relevant hydrographic and hydrochemical parameters from previously non-publicly available cruise data sets in the Arctic, Atlantic and Southern Ocean have been retrieved and merged to a new database: CARINA (CARbon IN the Atlantic). These data have gone through rigorous quality control (QC) procedures to assure the highest possible quality and consistency. The data for most of the measured parameters in the CARINA data base were objectively examined in order to quantify systematic differences in the reported values, i.e. secondary quality control. Systematic biases found in the data have been corrected in the data products, i.e. three merged data files with measured, calculated and interpolated data for each of the three CARINA regions; Arctic, Atlantic and Southern Ocean. Out of a total of 188 cruise entries in the CARINA database, 98 were conducted in the Atlantic Ocean and of these, 75 cruises report alkalinity values. Here we present details of the secondary QC on alkalinity for the Atlantic Ocean part of CARINA. Procedures of quality control, including crossover analysis between cruises and inversion analysis of all crossover data are briefly described. Adjustments were applied to the alkalinity values for 16 of the cruises in the Atlantic Ocean region. With these adjustments the CARINA database is consistent both internally as well as with GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s. Based on our analysis we estimate the internal accuracy of the CARINA-ATL alkalinity data to be 3.3 μmol kg-1. The CARINA data are now suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation.

CARINA: nutrient data in the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Tanhua, T.; Brown, P. J.; Key, R. M.

2009-11-01

Data on carbon and carbon-relevant hydrographic and hydrochemical parameters from previously non-publicly available cruise data sets in the Arctic, Atlantic and Southern Ocean have been retrieved and merged to a new database: CARINA (CARbon IN the Atlantic). These data have gone through rigorous quality control (QC) procedures to assure the highest possible quality and consistency. The data for most of the measured parameters in the CARINA data base were objectively examined in order to quantify systematic differences in the reported values, i.e. secondary quality control. Systematic biases found in the data have been corrected in the data products, i.e. three merged data files with measured, calculated and interpolated data for each of the three CARINA regions; Arctic Mediterranean Seas, Atlantic and Southern Ocean. Out of a total of 188 cruise entries in the CARINA database, 98 were conducted in the Atlantic Ocean and of these 84 cruises report nitrate values, 79 silicate, and 78 phosphate. Here we present details of the secondary QC for nutrients for the Atlantic Ocean part of CARINA. Procedures of quality control, including crossover analysis between cruises and inversion analysis of all crossover data are briefly described. Adjustments were applied to the nutrient values for 43 of the cruises in the Atlantic Ocean region. With these adjustments the CARINA database is consistent both internally as well as with GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s (Key et al., 2004). Based on our analysis we estimate the internal accuracy of the CARINA-ATL nutrient data to be: nitrate 1.5%; phosphate 2.6%; silicate 3.1%. The CARINA data are now suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation.

CARINA: nutrient data in the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Tanhua, T.; Brown, P. J.; Key, R. M.

2009-07-01

Data on carbon and carbon-relevant hydrographic and hydrochemical parameters from previously non-publicly available cruise data sets in the Arctic, Atlantic and Southern Ocean have been retrieved and merged to a new database: CARINA (CARbon IN the Atlantic). These data have gone through rigorous quality control (QC) procedures to assure the highest possible quality and consistency. The data for most of the measured parameters in the CARINA data base were objectively examined in order to quantify systematic differences in the reported values, i.e. secondary quality control. Systematic biases found in the data have been corrected in the data products, i.e. three merged data files with measured, calculated and interpolated data for each of the three CARINA regions; Arctic, Atlantic and Southern Ocean. Out of a total of 188 cruise entries in the CARINA database, 98 were conducted in the Atlantic Ocean and of these 84 cruises report nitrate values, 79 silicate, and 78 phosphate. Here we present details of the secondary QC for nutrients for the Atlantic Ocean part of CARINA. Procedures of quality control, including crossover analysis between cruises and inversion analysis of all crossover data are briefly described. Adjustments were applied to the nutrient values for 43 of the cruises in the Atlantic Ocean region. With these adjustments the CARINA database is consistent both internally as well as with GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s (Key et al., 2004). Based on our analysis we estimate the internal accuracy of the CARINA-ATL nutrient data to be: nitrate 1.5%; phosphate 2.6%; silicate 3.1%. The CARINA data are now suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation.

CARINA alkalinity data in the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Velo, A.; Perez, F. F.; Brown, P.; Tanhua, T.; Schuster, U.; Key, R. M.

2009-11-01

Data on carbon and carbon-relevant hydrographic and hydrochemical parameters from previously non-publicly available cruise data sets in the Arctic, Atlantic and Southern Ocean have been retrieved and merged to a new database: CARINA (CARbon IN the Atlantic). These data have gone through rigorous quality control (QC) procedures to assure the highest possible quality and consistency. The data for most of the measured parameters in the CARINA data base were objectively examined in order to quantify systematic differences in the reported values, i.e. secondary quality control. Systematic biases found in the data have been corrected in the data products, i.e. three merged data files with measured, calculated and interpolated data for each of the three CARINA regions; Arctic, Atlantic and Southern Ocean. Out of a total of 188 cruise entries in the CARINA database, 98 were conducted in the Atlantic Ocean and of these, 75 cruises report alkalinity values. Here we present details of the secondary QC on alkalinity for the Atlantic Ocean part of CARINA. Procedures of quality control, including crossover analysis between cruises and inversion analysis of all crossover data are briefly described. Adjustments were applied to the alkalinity values for 16 of the cruises in the Atlantic Ocean region. With these adjustments the CARINA database is consistent both internally as well as with GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s. Based on our analysis we estimate the internal accuracy of the CARINA-ATL alkalinity data to be 3.3 μmol kg-1. The CARINA data are now suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation.

Atlantic and indian oceans pollution in africa

NASA Astrophysics Data System (ADS)

Abubakar, Babagana

Africa is the second largest and most populated continent after Asia. Geographically it is located between the Atlantic and Indian Oceans. Most of the Africa's most populated and industrialized cities are located along the coast of the continent facing the Atlantic and Indian Oceans, example of such cities include Casablanca, Dakar, Accra, Lagos, Luanda and Cape town all facing the Atlantic Ocean and cities like East London, Durban, Maputo, Dar-es-salaam and Mogadishu are all facing the Indian Ocean. As a result of the geographical locations of African Coastal Cities plus increase in their population, industries, sea port operations, petroleum exploration activities, trafficking of toxic wastes and improper waste management culture lead to the incessant increase in the pollution of the two oceans. NATURE OF POLLUTION OF THE ATLANTIC OCEAN i. The petroleum exploration activities going on along the coast of "Gulf of Guinea" region and Angola continuously causes oil spillages in the process of drilling, bunkering and discharging of petroleum products in the Atlantic Ocean. ii. The incessant degreasing of the Sea Ports "Quay Aprons" along the Coastal cities of Lagos, Luanda, Cape Town etc are continuously polluting the Atlantic Ocean with chemicals. iii. Local wastes generated from the houses located in the coastal cities are always finding their ways into the Atlantic Ocean. NATURE OF POLLUTION OF THE INDIAN OCEAN i. Unlike the Atlantic ocean where petroleum is the major pollutant, the Indian Ocean is polluted by Toxic / Radioactive waste suspected to have been coming from the developed nations as reported by the United Nations Environmental Programme after the Tsunami disaster in December 2004 especially along the coast of Somalia. ii. The degreasing of the Quay Aprons at Port Elizabeth, Maputo, Dar-es-Salaam and Mongolism Sea Ports are also another major source polluting the Indian Ocean. PROBLEMS GENERATED AS A RESULT OF THE OCEANS POLLUTION i. Recent report

76 FR 31235 - Safety Zone; Ocean City Air Show, Atlantic Ocean, Ocean City, MD

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-31

...-AA00 Safety Zone; Ocean City Air Show, Atlantic Ocean, Ocean City, MD AGENCY: Coast Guard, DHS. ACTION... in the vicinity of Ocean City, MD to support the Ocean City Air Show. This action is necessary to provide for the safety of life on navigable waters during the Ocean City Air Show. This action is intended...

Potential Impact of North Atlantic Climate Variability on Ocean Biogeochemical Processes

NASA Astrophysics Data System (ADS)

Liu, Y.; Muhling, B.; Lee, S. K.; Muller-Karger, F. E.; Enfield, D. B.; Lamkin, J. T.; Roffer, M. A.

2016-02-01

Previous studies have shown that upper ocean circulations largely determine primary production in the euphotic layers, here the global ocean model with biogeochemistry (GFDL's Modular Ocean Model with TOPAZ biogeochemistry) forced with the ERA-Interim is used to simulate the natural variability of biogeochemical processes in global ocean during 1979-present. Preliminary results show that the surface chlorophyll is overall underestimated in MOM-TOPAZ, but its spatial pattern is fairly realistic. Relatively high chlorophyll variability is shown in the subpolar North Atlantic, northeastern tropical Atlantic, and equatorial Atlantic. Further analysis suggests that the chlorophyll variability in the North Atlantic Ocean is affected by long-term climate variability. For the subpolar North Atlantic region, the chlorophyll variability is light-limited and is significantly correlated with North Atlantic Oscillation. A dipole pattern of chlorophyll variability is found between the northeastern tropical Atlantic and equatorial Atlantic. For the northeastern North Atlantic, the chlorophyll variability is significantly correlated with Atlantic Meridional Mode (AMM) and Atlantic Multidecadal Oscillation (AMO). During the negative phase of AMM and AMO, the increased trade wind in the northeast North Atlantic can lead to increased upwelling of nutrients. In the equatorial Atlantic region, the chlorophyll variability is largely link to Atlantic-Niño and associated equatorial upwelling of nutrients. The potential impact of climate variability on the distribution of pelagic fishes (i.e. yellowfin tuna) are discussed.

The Oceanic Contribution to Atlantic Multi-Decadal Variability

NASA Astrophysics Data System (ADS)

Wills, R. C.; Armour, K.; Battisti, D. S.; Hartmann, D. L.

2017-12-01

Atlantic multi-decadal variability (AMV) is typically associated with variability in ocean heat transport (OHT) by the Atlantic Meridional Overturning Circulation (AMOC). However, recent work has cast doubt on this connection by showing that slab-ocean climate models, in which OHT cannot vary, exhibit similar variability. Here, we apply low-frequency component analysis to isolate the variability of Atlantic sea-surface temperatures (SSTs) that occurs on decadal and longer time scales. In observations and in pre-industrial control simulations of comprehensive climate models, we find that AMV is confined to the extratropics, with the strongest temperature anomalies in the North Atlantic subpolar gyre. We show that warm subpolar temperatures are associated with a strengthened AMOC, increased poleward OHT, and local heat fluxes from the ocean into the atmosphere. In contrast, the traditional index of AMV based on the basin-averaged SST anomaly shows warm temperatures preceded by heat fluxes from the atmosphere into the ocean, consistent with the atmosphere driving this variability, and shows a weak relationship with AMOC. The autocorrelation time of the basin-averaged SST index is 1 year compared to an autocorrelation time of 5 years for the variability of subpolar temperatures. This shows that multi-decadal variability of Atlantic SSTs is sustained by OHT variability associated with AMOC, while atmosphere-driven SST variability, such as exists in slab-ocean models, contributes primarily on interannual time scales.

Atmospheric Blocking and Atlantic Multi-Decadal Ocean Variability

NASA Technical Reports Server (NTRS)

Hakkinen, Sirpa; Rhines, Peter B.; Worthen, Denise L.

2011-01-01

Atmospheric blocking over the northern North Atlantic involves isolation of large regions of air from the westerly circulation for 5-14 days or more. From a recent 20th century atmospheric reanalysis (1,2) winters with more frequent blocking persist over several decades and correspond to a warm North Atlantic Ocean, in-phase with Atlantic multi-decadal ocean variability (AMV). Ocean circulation is forced by wind-stress curl and related air/sea heat exchange, and we find that their space-time structure is associated with dominant blocking patterns: weaker ocean gyres and weaker heat exchange contribute to the warm phase of AMV. Increased blocking activity extending from Greenland to British Isles is evident when winter blocking days of the cold years (1900-1929) are subtracted from those of the warm years (1939-1968).

Atlantic Ocean CARINA data: overview and salinity adjustments

NASA Astrophysics Data System (ADS)

Tanhua, T.; Steinfeldt, R.; Key, R. M.; Brown, P.; Gruber, N.; Wanninkhof, R.; Perez, F.; Körtzinger, A.; Velo, A.; Schuster, U.; van Heuven, S.; Bullister, J. L.; Stendardo, I.; Hoppema, M.; Olsen, A.; Kozyr, A.; Pierrot, D.; Schirnick, C.; Wallace, D. W. R.

2009-08-01

Water column data of carbon and carbon-relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruise data sets in the Arctic, Atlantic and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon IN the Atlantic). The data have gone through rigorous quality control procedures to assure the highest possible quality and consistency. The data for the pertinent parameters in the CARINA database were objectively examined in order to quantify systematic differences in the reported values, i.e. secondary quality control. Systematic biases found in the data have been corrected in the data products, i.e. three merged data files with measured, calculated and interpolated data for each of the three CARINA regions, i.e. Arctic, Atlantic and Southern Ocean. Ninety-eight of the cruises in the CARINA database were conducted in the Atlantic Ocean, defined here as the region south of the Greenland-Iceland-Scotland Ridge and north of about 30° S. Here we present an overview of the Atlantic Ocean synthesis of the CARINA data and the adjustments that were applied to the data product. We also report details of the secondary QC for salinity for this data set. Procedures of quality control - including crossover analysis between stations and inversion analysis of all crossover data - are briefly described. Adjustments to salinity measurements were applied to the data from 10 cruises in the Atlantic Ocean region. Based on our analysis we estimate the internal accuracy of the CARINA-ATL salinity data to be 4.1 ppm. With these adjustments the CARINA database is consistent both internally as well as with GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s (Key et al., 2004), and is now suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation.

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

Atlantic Ocean CARINA data: overview and salinity adjustments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanhua, T.; Steinfeldt, R.; Key, Robert

2010-01-01

Water column data of carbon and carbon-relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruise data sets in the Arctic Mediterranean Seas, Atlantic and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon dioxide IN the Atlantic Ocean). The data have gone through rigorous quality control procedures to assure the highest possible quality and consistency. The data for the pertinent parameters in the CARINA database were objectively examined in order to quantify systematic differences in the reported values, i.e. secondary quality control. Systematic biases found in the data have been corrected in the threemore » data products: merged data files with measured, calculated and interpolated data for each of the three CARINA regions, i.e. the Arctic Mediterranean Seas, the Atlantic and the Southern Ocean. These products have been corrected to be internally consistent. Ninety-eight of the cruises in the CARINA database were conducted in the Atlantic Ocean, defined here as the region south of the Greenland-Iceland-Scotland Ridge and north of about 30 S. Here we present an overview of the Atlantic Ocean synthesis of the CARINA data and the adjustments that were applied to the data product. We also report the details of the secondary QC (Quality Control) for salinity for this data set. Procedures of quality control including crossover analysis between stations and inversion analysis of all crossover data are briefly described. Adjustments to salinity measurements were applied to the data from 10 cruises in the Atlantic Ocean region. Based on our analysis we estimate the internal consistency of the CARINA-ATL salinity data to be 4.1 ppm. With these adjustments the CARINA data products are consistent both internally was well as with GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s, and is now suitable for accurate assessments of, for example, oceanic carbon

Atlantic Ocean CARINA data: overview and salinity adjustments

NASA Astrophysics Data System (ADS)

Tanhua, T.; Steinfeldt, R.; Key, R. M.; Brown, P.; Gruber, N.; Wanninkhof, R.; Perez, F.; Körtzinger, A.; Velo, A.; Schuster, U.; van Heuven, S.; Bullister, J. L.; Stendardo, I.; Hoppema, M.; Olsen, A.; Kozyr, A.; Pierrot, D.; Schirnick, C.; Wallace, D. W. R.

2010-02-01

Water column data of carbon and carbon-relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruise data sets in the Arctic Mediterranean Seas, Atlantic and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon dioxide IN the Atlantic Ocean). The data have gone through rigorous quality control procedures to assure the highest possible quality and consistency. The data for the pertinent parameters in the CARINA database were objectively examined in order to quantify systematic differences in the reported values, i.e. secondary quality control. Systematic biases found in the data have been corrected in the three data products: merged data files with measured, calculated and interpolated data for each of the three CARINA regions, i.e. the Arctic Mediterranean Seas, the Atlantic and the Southern Ocean. These products have been corrected to be internally consistent. Ninety-eight of the cruises in the CARINA database were conducted in the Atlantic Ocean, defined here as the region south of the Greenland-Iceland-Scotland Ridge and north of about 30° S. Here we present an overview of the Atlantic Ocean synthesis of the CARINA data and the adjustments that were applied to the data product. We also report the details of the secondary QC (Quality Control) for salinity for this data set. Procedures of quality control - including crossover analysis between stations and inversion analysis of all crossover data - are briefly described. Adjustments to salinity measurements were applied to the data from 10 cruises in the Atlantic Ocean region. Based on our analysis we estimate the internal consistency of the CARINA-ATL salinity data to be 4.1 ppm. With these adjustments the CARINA data products are consistent both internally as well as with GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s, and is now suitable for accurate assessments of, for example, oceanic carbon

Decadal Variability of Temperature and Salinity in the Northwest Atlantic Ocean

NASA Astrophysics Data System (ADS)

Mishonov, A. V.; Seidov, D.; Reagan, J. R.; Boyer, T.; Parsons, A. R.

2017-12-01

There are only a few regions in the World Ocean where the density of observations collected over the past 60 years is sufficient for reliable data mapping with spatial resolutions finer than one-degree. The Northwest Atlantic basin is one such regions where a spatial resolution of gridded temperature and salinity fields, comparable to those generated by eddy-resolving numerical models of ocean circulation, has recently becomes available. Using the new high-resolution Northwest Atlantic Regional Climatology, built on quarter-degree and one-tenth-degree resolution fields, we analyzed decadal variability and trends of temperature and salinity over 60 years in the Northwest Atlantic, and two 30-year ocean climates of 1955-1984 and 1985-2012 to evaluate the oceanic climate shift in this region. The 30-year climate shift is demonstrated using an innovative 3-D visualization of temperature and salinity. Spatial and temporal variability of heat accumulation found in previous research of the entire North Atlantic Ocean persists in the Northwest Atlantic Ocean. Salinity changes between two 30-year climates were also computed and are discussed.

Role of tropical Indian and Atlantic Oceans variability on ENSO

NASA Astrophysics Data System (ADS)

Prodhomme, Chloé; Terray, Pascal; Masson, Sebastien; Boschat, Ghyslaine

2014-05-01

There are strong evidences of an interaction between tropical Indian, Atlantic and Pacific Oceans. Nevertheless, these interactions remain deeply controversial. While some authors claim the tropical Indian and Atlantic oceans only play a passive role with respect to ENSO, others suggest a driving role for these two basins on ENSO. The mecanisms underlying these relations are not fully understood and, in the Indian Ocean, the possible role of both modes of tropical variability (the Indian Ocean Dipole (IOD) and the Indian Ocean Basin mode (IOB)) remain unclear. To better quantify and understand how the variability of the tropical Indian and Atlantic Oceans impact ENSO variability, we performed two sensitivity experiments using the SINTEX-F2 coupled model. For each experiment, we suppressed the variability of SST and the air-sea coupling in either the tropical Indian Ocean or tropical Atlantic Ocean by applying a strong nudging of the SST to the observed SST climatology. In both experiments, the ENSO periodicity increases. In the Atlantic experiment, our understanding of this increased periodicity is drastically limited by the strongly biased mean state in this region. Conversely, in the Indian Ocean experiment, the increase of ENSO periodicity is related to the absence of the IOB following the El Niño peak, which leads to a decrease of westerly winds in the western Pacific during late winter and spring after the peak. These weaker westerlies hinders the transition to a La Niña phase and thus increase the duration and periodicity of the event.

Atlantic Meridional Overturning Circulation slowdown cooled the subtropical ocean

PubMed Central

Cunningham, Stuart A; Roberts, Christopher D; Frajka-Williams, Eleanor; Johns, William E; Hobbs, Will; Palmer, Matthew D; Rayner, Darren; Smeed, David A; McCarthy, Gerard

2013-01-01

[1] Observations show that the upper 2 km of the subtropical North Atlantic Ocean cooled throughout 2010 and remained cold until at least December 2011. We show that these cold anomalies are partly driven by anomalous air-sea exchange during the cold winters of 2009/2010 and 2010/2011 and, more surprisingly, by extreme interannual variability in the ocean's northward heat transport at 26.5°N. This cooling driven by the ocean's meridional heat transport affects deeper layers isolated from the atmosphere on annual timescales and water that is entrained into the winter mixed layer thus lowering winter sea surface temperatures. Here we connect, for the first time, variability in the northward heat transport carried by the Atlantic Meridional Overturning Circulation to widespread sustained cooling of the subtropical North Atlantic, challenging the prevailing view that the ocean plays a passive role in the coupled ocean-atmosphere system on monthly-to-seasonal timescales. PMID:26074634

Atlantic Meridional Overturning Circulation slowdown cooled the subtropical ocean.

PubMed

Cunningham, Stuart A; Roberts, Christopher D; Frajka-Williams, Eleanor; Johns, William E; Hobbs, Will; Palmer, Matthew D; Rayner, Darren; Smeed, David A; McCarthy, Gerard

2013-12-16

[1] Observations show that the upper 2 km of the subtropical North Atlantic Ocean cooled throughout 2010 and remained cold until at least December 2011. We show that these cold anomalies are partly driven by anomalous air-sea exchange during the cold winters of 2009/2010 and 2010/2011 and, more surprisingly, by extreme interannual variability in the ocean's northward heat transport at 26.5°N. This cooling driven by the ocean's meridional heat transport affects deeper layers isolated from the atmosphere on annual timescales and water that is entrained into the winter mixed layer thus lowering winter sea surface temperatures. Here we connect, for the first time, variability in the northward heat transport carried by the Atlantic Meridional Overturning Circulation to widespread sustained cooling of the subtropical North Atlantic, challenging the prevailing view that the ocean plays a passive role in the coupled ocean-atmosphere system on monthly-to-seasonal timescales.

CARINA TCO2 data in the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Pierrot, D.; Brown, P.; van Heuven, S.; Tanhua, T.; Schuster, U.; Wanninkhof, R.; Key, R. M.

2010-01-01

Water column data of carbon and carbon-relevant hydrographic and hydrochemical parameters from 188 cruises in the Arctic, Atlantic and Southern Ocean have been retrieved and merged in a new data base: the CARINA (CARbon IN the Atlantic) Project. These data have gone through rigorous quality control (QC) procedures to assure the highest possible quality and consistency. Secondary quality control, which involved objective study of data in order to quantify systematic differences in the reported values, was performed for the pertinent parameters in the CARINA data base. Systematic biases in the data have been corrected in the data products. The products are three merged data files with measured, adjusted and interpolated data of all cruises for each of the three CARINA regions (Arctic, Atlantic and Southern Ocean). Ninety-eight cruises were conducted in the "Atlantic" defined as the region south of the Greenland-Iceland-Scotland Ridge and north of about 30° S. Here we report the details of the secondary QC which was done on the total dissolved inorganic carbon (TCO2) data and the adjustments that were applied to yield the final data product in the Atlantic. Procedures of quality control - including crossover analysis between stations and inversion analysis of all crossover data - are briefly described. Adjustments were applied to TCO2 measurements for 17 of the cruises in the Atlantic Ocean region. With these adjustments, the CARINA data base is consistent both internally as well as with GLODAP data, an oceanographic data set based on the WOCE Hydrographic Program in the 1990s, and is now suitable for accurate assessments of, for example, regional oceanic carbon inventories, uptake rates and model validation.

Tropical Dominance of N2 Fixation in the North Atlantic Ocean

NASA Astrophysics Data System (ADS)

Marconi, Dario; Sigman, Daniel M.; Casciotti, Karen L.; Campbell, Ethan C.; Alexandra Weigand, M.; Fawcett, Sarah E.; Knapp, Angela N.; Rafter, Patrick A.; Ward, Bess B.; Haug, Gerald H.

2017-10-01

To investigate the controls on N2 fixation and the role of the Atlantic in the global ocean's fixed nitrogen (N) budget, Atlantic N2 fixation is calculated by combining meridional nitrate fluxes across World Ocean Circulation Experiment sections with observed nitrate 15N/14N differences between northward and southward transported nitrate. N2 fixation inputs of 27.1 ± 4.3 Tg N/yr and 3.0 ± 0.5 Tg N/yr are estimated north of 11°S and 24°N, respectively. That is, 90% of the N2 fixation in the Atlantic north of 11°S occurs south of 24°N in a region with upwelling that imports phosphorus (P) in excess of N relative to phytoplankton requirements. This suggests that, under the modern iron-rich conditions of the equatorial and North Atlantic, N2 fixation occurs predominantly in response to P-bearing, N-poor conditions. We estimate a N2 fixation rate of 30.5 ± 4.9 Tg N/yr north of 30°S, implying only 3 Tg N/yr between 30° and 11°S, despite evidence of P-bearing, N-poor surface waters in this region as well; this is consistent with iron limitation of N2 fixation in the South Atlantic. Since the ocean flows through the Atlantic surface in <2,500 years, similar to the residence time of oceanic fixed N, Atlantic N2 fixation can stabilize the N-to-P ratio of the global ocean. However, the calculated rate of Atlantic N2 fixation is a small fraction of global ocean estimates for either N2 fixation or fixed N loss. This suggests that, in the modern ocean, an approximate balance between N loss and N2 fixation is achieved within the combined Indian and Pacific basins.

Sublatitudinal Isotope Heterogeneity of The Atlantic and Adjacent Continents: A Relation To The Litospheric Plates and Superplums

NASA Astrophysics Data System (ADS)

Mironov, Yu. V.; Ryakhovsky, V. M.; Pustovoy, A. A.; Lapidus, I. V.

Four Sr-Nd-Pb isotope sublatitudinal provinces are chosen in the Atlantic and on ad- jacent continents. They include mid-ocean ridges, oceanic rises and islands, as well as Late Mesozoic - Cenozoic continental rifts and traps. A modified Zindler-Hart "man- tle tetrahedron" (1986) have been used for rock systematics. Its major classification element alongside with known end-members (DM, HIMU, EM1, EM2) is any in- tratetrahedron component F ("focal") (Mironov et al., 2000; Rundquist et al., 2000; Ryakhovsky, 2000). It represents average characteristic of all known intratetrahedron components (FOZO, C, PREMA etc.), updated by methods of multidimensional statis- tics. Northern province includes Mid-Atlantic Ridge from a southern part of Reykjanes ridge up to 24S, numerous islands and rises, located at the same latitudes, Cameroon Line, African and European rifts, Aden and Red sea spreading centres, and also Co- mores in Indian ocean. The main composition dispersion of volcanics from withinplate oceanic and continental structures is determined by mixture of F and HIMU (rarely with admixture EM2). MORB within this area are characterized by stable admixture HIMU. Similar composition have the rocks in Bouvet-Antarctic province, within the limits of which the rises Spiss and Shona, the most southern part of Mid-Atlantic ridge, island Bouvet, an adjacent part of Southwest-Indian Ridge, and also traps and rifts on northern coast of Antarctic Continent are located. The Southern province lies in outlines of known Southern hemisphere DUPAL-anomaly (Hart, 1984). The with- inplate oceanic rocks (Gough, Tristan-da-Kunha, Walvis ridge, Rio Grande Plateau, Discovery) correspond to a mixture F + EM1 (sometimes F + EM1 + EM2) and are similar with traps of Southern America and Africa. Further to east this province is traced on islands and mid-ocean ridges in Indian ocean. MORB of Southern Atlantic and Indian ocean are enriched EM1. The Arctic province includes spreading ridges of

Carbon and Nutrient Cycling in the Southwestern Atlantic Ocean

NASA Astrophysics Data System (ADS)

Windom, Herbert; Piola, Alberto; McKee, Brent

2009-03-01

State of Knowledge on the Southwestern Atlantic Ocean Margin; Montevideo, Uruguay, 16-22 November 2008; The southwestern Atlantic Ocean margin (SWAOM), along the coasts of southern Brazil, Uruguay, and Argentina, is one of the most productive regions of the world ocean and is believed to be the largest carbon dioxide (CO2) sink in the Atlantic Ocean. The region is dominated by two major boundary currents (the Brazil and the Malvinas), which impinge on a broad continental shelf along southeastern South America and converge offshore of the Rio de la Plata, the largest source of freshwater to the South Atlantic Ocean. Scientific knowledge about this region is based on past research focused generally on processes within the confines of the waters of the individual countries and from single disciplines. However, the complex interactions of physical, chemical, and biological processes that control the transport and production in time and space across this region require multidisciplinary investigation and international cooperation. This led a group of more than 40 marine scientists from these countries and the United States to convene a workshop to review what is known about this region, to suggest how future multidisciplinary research might be organized, and to foster regional and North-South scientific cooperation.

Role of subsurface ocean in decadal climate predictability over the South Atlantic.

PubMed

Morioka, Yushi; Doi, Takeshi; Storto, Andrea; Masina, Simona; Behera, Swadhin K

2018-06-04

Decadal climate predictability in the South Atlantic is explored by performing reforecast experiments using a coupled general circulation model with two initialization schemes; one is assimilated with observed sea surface temperature (SST) only, and the other is additionally assimilated with observed subsurface ocean temperature and salinity. The South Atlantic is known to undergo decadal variability exhibiting a meridional dipole of SST anomalies through variations in the subtropical high and ocean heat transport. Decadal reforecast experiments in which only the model SST is initialized with the observation do not predict well the observed decadal SST variability in the South Atlantic, while the other experiments in which the model SST and subsurface ocean are initialized with the observation skillfully predict the observed decadal SST variability, particularly in the Southeast Atlantic. In-depth analysis of upper-ocean heat content reveals that a significant improvement of zonal heat transport in the Southeast Atlantic leads to skillful prediction of decadal SST variability there. These results demonstrate potential roles of subsurface ocean assimilation in the skillful prediction of decadal climate variability over the South Atlantic.

South Atlantic circulation in a world ocean model

NASA Astrophysics Data System (ADS)

England, Matthew H.; Garçon, Véronique C.

1994-09-01

The circulation in the South Atlantic Ocean has been simulated within a global ocean general circulation model. Preliminary analysis of the modelled ocean circulation in the region indicates a rather close agreement of the simulated upper ocean flows with conventional notions of the large-scale geostrophic currents in the region. The modelled South Atlantic Ocean witnesses the return flow and export of North Atlantic Deep Water (NADW) at its northern boundary, the inflow of a rather barotropic Antarctic Circumpolar Current (ACC) through the Drake Passage, and the inflow of warm saline Agulhas water around the Cape of Good Hope. The Agulhas leakage amounts to 8.7 Sv, within recent estimates of the mass transport shed westward at the Agulhas retroflection. Topographic steering of the ACC dominates the structure of flow in the circumpolar ocean. The Benguela Current is seen to be fed by a mixture of saline Indian Ocean water (originating from the Agulhas Current) and fresher Subantarctic surface water (originating in the ACC). The Benguela Current is seen to modify its flow and fate with depth; near the surface it flows north-westwards bifurcating most of its transport northward into the North Atlantic Ocean (for ultimate replacement of North Atlantic surface waters lost to the NADW conveyor). Deeper in the water column, more of the Benguela Current is destined to return with the Brazil Current, though northward flows are still generated where the Benguela Current extension encounters the coast of South America. At intermediate levels, these northward currents trace the flow of Antarctic Intermediate Water (AAIW) equatorward, though even more AAIW is seen to recirculate poleward in the subtropical gyre. In spite of the model's rather coarse resolution, some subtle features of the Brazil-Malvinas Confluence are simulated rather well, including the latitude at which the two currents meet. Conceptual diagrams of the recirculation and interocean exchange of thermocline

33 CFR 334.580 - Atlantic Ocean near Port Everglades, Fla.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Atlantic Ocean near Port Everglades, Fla. 334.580 Section 334.580 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.580 Atlantic Ocean...

33 CFR 334.580 - Atlantic Ocean near Port Everglades, Fla.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false Atlantic Ocean near Port Everglades, Fla. 334.580 Section 334.580 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.580 Atlantic Ocean...

33 CFR 334.580 - Atlantic Ocean near Port Everglades, Fla.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Atlantic Ocean near Port Everglades, Fla. 334.580 Section 334.580 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.580 Atlantic Ocean...

33 CFR 334.580 - Atlantic Ocean near Port Everglades, Fla.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Atlantic Ocean near Port Everglades, Fla. 334.580 Section 334.580 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.580 Atlantic Ocean...

33 CFR 334.580 - Atlantic Ocean near Port Everglades, Fla.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Atlantic Ocean near Port Everglades, Fla. 334.580 Section 334.580 Navigation and Navigable Waters CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.580 Atlantic Ocean...

Comparison of Deep-Water Viromes from the Atlantic Ocean and the Mediterranean Sea

PubMed Central

Winter, Christian; Garcia, Juan A. L.; Weinbauer, Markus G.; DuBow, Michael S.; Herndl, Gerhard J.

2014-01-01

The aim of this study was to compare the composition of two deep-sea viral communities obtained from the Romanche Fracture Zone in the Atlantic Ocean (collected at 5200 m depth) and the southwest Mediterranean Sea (from 2400 m depth) using a pyro-sequencing approach. The results are based on 18.7% and 6.9% of the sequences obtained from the Atlantic Ocean and the Mediterranean Sea, respectively, with hits to genomes in the non-redundant viral RefSeq database. The identifiable richness and relative abundance in both viromes were dominated by archaeal and bacterial viruses accounting for 92.3% of the relative abundance in the Atlantic Ocean and for 83.6% in the Mediterranean Sea. Despite characteristic differences in hydrographic features between the sampling sites in the Atlantic Ocean and the Mediterranean Sea, 440 virus genomes were found in both viromes. An additional 431 virus genomes were identified in the Atlantic Ocean and 75 virus genomes were only found in the Mediterranean Sea. The results indicate that the rather contrasting deep-sea environments of the Atlantic Ocean and the Mediterranean Sea share a common core set of virus types constituting the majority of both virus communities in terms of relative abundance (Atlantic Ocean: 81.4%; Mediterranean Sea: 88.7%). PMID:24959907

33 CFR 110.185 - Atlantic Ocean, off the Port of Palm Beach, FL.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Atlantic Ocean, off the Port of... HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Anchorage Grounds § 110.185 Atlantic Ocean, off the Port... regulations. (1) Vessels in the Atlantic Ocean near Lake Worth Inlet awaiting berthing space at the Port of...

33 CFR 110.185 - Atlantic Ocean, off the Port of Palm Beach, FL.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Atlantic Ocean, off the Port of... HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Anchorage Grounds § 110.185 Atlantic Ocean, off the Port... regulations. (1) Vessels in the Atlantic Ocean near Lake Worth Inlet awaiting berthing space at the Port of...

33 CFR 110.185 - Atlantic Ocean, off the Port of Palm Beach, FL.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Atlantic Ocean, off the Port of... HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Anchorage Grounds § 110.185 Atlantic Ocean, off the Port... regulations. (1) Vessels in the Atlantic Ocean near Lake Worth Inlet awaiting berthing space at the Port of...

33 CFR 110.185 - Atlantic Ocean, off the Port of Palm Beach, FL.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Atlantic Ocean, off the Port of... HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Anchorage Grounds § 110.185 Atlantic Ocean, off the Port... regulations. (1) Vessels in the Atlantic Ocean near Lake Worth Inlet awaiting berthing space at the Port of...

33 CFR 110.185 - Atlantic Ocean, off the Port of Palm Beach, FL.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Atlantic Ocean, off the Port of... HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Anchorage Grounds § 110.185 Atlantic Ocean, off the Port... regulations. (1) Vessels in the Atlantic Ocean near Lake Worth Inlet awaiting berthing space at the Port of...

Ocean impact on decadal Atlantic climate variability revealed by sea-level observations.

PubMed

McCarthy, Gerard D; Haigh, Ivan D; Hirschi, Joël J-M; Grist, Jeremy P; Smeed, David A

2015-05-28

Decadal variability is a notable feature of the Atlantic Ocean and the climate of the regions it influences. Prominently, this is manifested in the Atlantic Multidecadal Oscillation (AMO) in sea surface temperatures. Positive (negative) phases of the AMO coincide with warmer (colder) North Atlantic sea surface temperatures. The AMO is linked with decadal climate fluctuations, such as Indian and Sahel rainfall, European summer precipitation, Atlantic hurricanes and variations in global temperatures. It is widely believed that ocean circulation drives the phase changes of the AMO by controlling ocean heat content. However, there are no direct observations of ocean circulation of sufficient length to support this, leading to questions about whether the AMO is controlled from another source. Here we provide observational evidence of the widely hypothesized link between ocean circulation and the AMO. We take a new approach, using sea level along the east coast of the United States to estimate ocean circulation on decadal timescales. We show that ocean circulation responds to the first mode of Atlantic atmospheric forcing, the North Atlantic Oscillation, through circulation changes between the subtropical and subpolar gyres--the intergyre region. These circulation changes affect the decadal evolution of North Atlantic heat content and, consequently, the phases of the AMO. The Atlantic overturning circulation is declining and the AMO is moving to a negative phase. This may offer a brief respite from the persistent rise of global temperatures, but in the coupled system we describe, there are compensating effects. In this case, the negative AMO is associated with a continued acceleration of sea-level rise along the northeast coast of the United States.

The Distribution of Dissolved Iron in the West Atlantic Ocean

PubMed Central

Rijkenberg, Micha J. A.; Middag, Rob; Laan, Patrick; Gerringa, Loes J. A.; van Aken, Hendrik M.; Schoemann, Véronique; de Jong, Jeroen T. M.; de Baar, Hein J. W.

2014-01-01

Iron (Fe) is an essential trace element for marine life. Extremely low Fe concentrations limit primary production and nitrogen fixation in large parts of the oceans and consequently influence ocean ecosystem functioning. The importance of Fe for ocean ecosystems makes Fe one of the core chemical trace elements in the international GEOTRACES program. Despite the recognized importance of Fe, our present knowledge of its supply and biogeochemical cycle has been limited by mostly fragmentary datasets. Here, we present highly accurate dissolved Fe (DFe) values measured at an unprecedented high intensity (1407 samples) along the longest full ocean depth transect (17500 kilometers) covering the entire western Atlantic Ocean. DFe measurements along this transect unveiled details about the supply and cycling of Fe. External sources of Fe identified included off-shelf and river supply, hydrothermal vents and aeolian dust. Nevertheless, vertical processes such as the recycling of Fe resulting from the remineralization of sinking organic matter and the removal of Fe by scavenging still dominated the distribution of DFe. In the northern West Atlantic Ocean, Fe recycling and lateral transport from the eastern tropical North Atlantic Oxygen Minimum Zone (OMZ) dominated the DFe-distribution. Finally, our measurements showed that the North Atlantic Deep Water (NADW), the major driver of the so-called ocean conveyor belt, contains excess DFe relative to phosphate after full biological utilization and is therefore an important source of Fe for biological production in the global ocean. PMID:24978190

Role of the North Atlantic Ocean in Low Frequency Climate Variability

NASA Astrophysics Data System (ADS)

Danabasoglu, G.; Yeager, S. G.; Kim, W. M.; Castruccio, F. S.

2017-12-01

The Atlantic Ocean is a unique basin with its extensive, North - South overturning circulation, referred to as the Atlantic meridional overturning circulation (AMOC). AMOC is thought to represent the dynamical memory of the climate system, playing an important role in decadal and longer time scale climate variability as well as prediction of the earth's future climate on these time scales via its large heat and salt transports. This oceanic memory is communicated to the atmosphere primarily through the influence of persistent sea surface temperature (SST) variations. Indeed, many modeling studies suggest that ocean circulation, i.e., AMOC, is largely responsible for the creation of coherent SST variability in the North Atlantic, referred to as Atlantic Multidecadal Variability (AMV). AMV has been linked to many (multi)decadal climate variations in, e.g., Sahel and Brazilian rainfall, Atlantic hurricane activity, and Arctic sea-ice extent. In the absence of long, continuous observations, much of the evidence for the ocean's role in (multi)decadal variability comes from model simulations. Although models tend to agree on the role of the North Atlantic Oscillation in creating the density anomalies that proceed the changes in ocean circulation, model fidelity in representing variability characteristics, mechanisms, and air-sea interactions remains a serious concern. In particular, there is increasing evidence that models significantly underestimate low frequency variability in the North Atlantic compared to available observations. Such model deficiencies can amplify the relative influence of external or stochastic atmospheric forcing in generating (multi)decadal variability, i.e., AMV, at the expense of ocean dynamics. Here, a succinct overview of the current understanding of the (North) Atlantic Ocean's role on the regional and global climate, including some outstanding questions, will be presented. In addition, a few examples of the climate impacts of the AMV via

Using Ocean Exploration in the Atlantic Canyons to Advance Conversations about Transatlantic Ocean Literacy

NASA Astrophysics Data System (ADS)

Keener, P.; Tuddenham, P. T.; Bishop, T.

2016-02-01

The National Oceanic and Atmospheric Administration (NOAA) Ship Okeanos Explorer spent the 2013 field season exploring a wide variety of seafloor features and biological communities in and between largely unexplored canyons in the Northeast Atlantic Ocean, revealing hot spots for biodiversity and providing new information about how these canyons change over time. During the expeditions, an interdisciplinary team of scientists from dozens of institutions and multiple sectors together with ocean educators and the public were able to observe via telepresence the deep Atlantic using NOAA's new remotely-operated vehicle Deep Discoverer. In a collaboration between the NOAA Office of Ocean Exploration and Research and The College of Exploration, along with partners in Canada and the European Union (EU), key exploration findings from the NOAA Ship Okeanos Explorer 2013 field season were designed into an online workshop in which 640 educators, scientists, government representatives, policy makers, and other interested stakeholders representing 40 states within the U.S. and 29 countries participated. The five-week long online offering, titled Deepwater Explorations in the North Atlantic Onboard the NOAA Ship Okeanos Explorer…Online Conversations to Advance Transatlantic Ocean Literacy, built upon the telepresence experience and served as a foundation for extending conversations begun approximately a year earlier on transatlantic ocean literacy, as called for in The Galway Statement. Scientific experts from the U.S., Canada, and the EU provided keynote addresses on deep-sea corals, methane seeps, deep-water canyons, seamounts, and biological diversity in this important area of our "shared Atlantic Ocean." This session will socialize key findings of the workshop based on an evaluation conducted at the conclusion of the workshop and offers insight into how online learning communities can advance ocean literacy and scientific understanding in support of The Galway Statement.

Anisotropic tomography of the Atlantic ocean

NASA Astrophysics Data System (ADS)

Silveira, G.; Stutzmann, E.

2003-04-01

We present a regional tri-dimensional model of the Atlantic Ocean with anisotropy. The model, derived from Rayleigh and Love phase velocity measurements, is defined from the Moho down to 300 km depth with a lateral resolution of about 500 km and is presented in terms of average isotropic S-wave velocity, azimuthal anisotropy and transverse isotropy. The cratons beneath North America, Brazil and Africa are clearly associated with fast S-wave velocity anomalies. The Mid Atlantic Ridge is a shallow structure in the North Atlantic corresponding to a negative velocity anomaly down to about 150 km depth. In contrast, the ridge negative signature is visible in the South Atlantic down to the deepest depth inverted, that is 300~km depth. This difference is probably related to the presence of hot-spots along or close to the ridge axis in the South Atlantic and may indicate a different mechanism for the ridge between the North and South Atlantic. Negative velocity anomalies are clearly associated with hot-spots from the surface down to at least 300km depth, they are much broader that the supposed size of the hot-spots and seem to be connected along a North-South direction. Down to 100 km depth, a fast S-wave velocity anomaly is extenting from Africa into the Atlantic Ocean within the zone defined as the Africa superswell area. This result indicates that the hot material rising from below does not reach the surface in this area but may be pushing the lithosphere upward. In most parts of the Atlantic, the azimuthal anisotropy directions remain stable with increasing depth. Close to the ridge, the fast S-wave velocity direction is roughly parallel to the sea floor spreading direction. The hot-spot anisotropy signature is striking beneath Bermuda, Cape Verde and Fernando Noronha islands where the fast S-wave velocity direction seems to diverge radially from the hot-spots. The Atlantic average radial anisotropy is similar to that of the PREM model, that is positive down to about

Coherent Multidecadal Atmospheric and Oceanic Variability in the North Atlantic: Blocking Corresponds with Warm Subpolar Ocean

NASA Technical Reports Server (NTRS)

Hakkinen, Sirpa M.; Rhines, P. B.; Worthen, D. L.

2012-01-01

Winters with frequent atmospheric blocking, in a band of latitudes from Greenland to Western Europe, are found to persist over several decades and correspond to a warm North Atlantic Ocean. This is evident in atmospheric reanalysis data, both modern and for the full 20th century. Blocking is approximately in phase with Atlantic multidecadal ocean variability (AMV). Wintertime atmospheric blocking involves a highly distorted jetstream, isolating large regions of air from the westerly circulation. It influences the ocean through windstress-curl and associated air/sea heat flux. While blocking is a relatively high-frequency phenomenon, it is strongly modulated over decadal timescales. The blocked regime (weaker ocean gyres, weaker air-sea heat flux, paradoxically increased transport of warm subtropical waters poleward) contributes to the warm phase of AMV. Atmospheric blocking better describes the early 20thC warming and 1996-2010 warm period than does the NAO index. It has roots in the hemispheric circulation and jet stream dynamics. Subpolar Atlantic variability covaries with distant AMOC fields: both these connections may express the global influence of the subpolar North Atlantic ocean on the global climate system.

33 CFR 165.714 - Regulated Navigation Area; Atlantic Ocean, Charleston, SC.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Regulated Navigation Area; Atlantic Ocean, Charleston, SC. 165.714 Section 165.714 Navigation and Navigable Waters COAST GUARD... § 165.714 Regulated Navigation Area; Atlantic Ocean, Charleston, SC. (a) Location. The following area is...

33 CFR 165.714 - Regulated Navigation Area; Atlantic Ocean, Charleston, SC.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Regulated Navigation Area; Atlantic Ocean, Charleston, SC. 165.714 Section 165.714 Navigation and Navigable Waters COAST GUARD... § 165.714 Regulated Navigation Area; Atlantic Ocean, Charleston, SC. (a) Location. The following area is...

33 CFR 165.714 - Regulated Navigation Area; Atlantic Ocean, Charleston, SC.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Regulated Navigation Area; Atlantic Ocean, Charleston, SC. 165.714 Section 165.714 Navigation and Navigable Waters COAST GUARD... § 165.714 Regulated Navigation Area; Atlantic Ocean, Charleston, SC. (a) Location. The following area is...

33 CFR 165.714 - Regulated Navigation Area; Atlantic Ocean, Charleston, SC.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Regulated Navigation Area; Atlantic Ocean, Charleston, SC. 165.714 Section 165.714 Navigation and Navigable Waters COAST GUARD... § 165.714 Regulated Navigation Area; Atlantic Ocean, Charleston, SC. (a) Location. The following area is...

33 CFR 165.714 - Regulated Navigation Area; Atlantic Ocean, Charleston, SC.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Regulated Navigation Area; Atlantic Ocean, Charleston, SC. 165.714 Section 165.714 Navigation and Navigable Waters COAST GUARD... § 165.714 Regulated Navigation Area; Atlantic Ocean, Charleston, SC. (a) Location. The following area is...

An out of phase coupling between the atmosphere and the ocean over the North Atlantic Ocean

NASA Astrophysics Data System (ADS)

Ribera, Pedro; Ordoñez, Paulina; Gallego, David; Peña-Ortiz, Cristina

2017-04-01

An oscillation band, with a period ranging between 40 and 60 years, has been identified as the most intense signal over the North Atlantic Ocean using several oceanic and atmospheric reanalyses between 1856 and the present. This signal represents the Atlantic Multidecadal Oscillation, an oscillation between warmer and colder than normal conditions in SST. Simultaneously, those changes in SST are accompanied by changes in atmospheric conditions represented by surface pressure, temperature and circulation. In fact, the evolution of the surface pressure pattern along this oscillation shows a North Atlantic Oscillation-like pattern, suggesting the existence of an out of phase coupling between atmospheric and oceanic conditions. Further analysis shows that the evolution of the oceanic SST distribution modifies atmospheric baroclinic conditions in the mid to high latitudes of the North Atlantic and leads the atmospheric variability by 6-7 years. If AMO represents the oceanic conditons and NAO represents the atmospheric variability then it could be said that AMO of one sign leads NAO of the opposite sign with a lag of 6-7 years. On the other hand, the evolution of atmospheric conditions, represented by pressure distribution patterns, favors atmospheric circulation anomalies and induces a heat advection which tends to change the sign of the existing SST distribution and oceanic conditions with a lag of 16-17 years. In this case, NAO of one sign leads AMO of the same sign with a lag of 16-17 years.

A Latitudinal Metabolome of the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Johnson, W.; Kido Soule, M. C.; Longnecker, K.; Kujawinski, E. B.

2016-02-01

Microbial consortia function via the exchange and transformation of small organic molecules or metabolites. These metabolites make up a pool of rapidly cycling organic matter in the ocean that is challenging to characterize due to its low concentrations. We seek to determine the distribution of these molecules and the factors that shape their abundance and flux. Through measurements of the abundance of a core set of metabolites, including nucleic acids, amino acids, sugars, vitamins, and signaling molecules, we gain a real-time snapshot of microbial activity. We used a targeted metabolomics technique to profile metabolite abundance in particulate and dissolved organic matter extracts collected from a 14,000 km transect running from 38˚S to 55˚N in the Western Atlantic Ocean. This extensive dataset is the first of its kind in the Atlantic Ocean and allows us to explore connections among metabolites as well as latitudinal trends in metabolite abundance. We found changes in the intracellular abundance of certain metabolites between low and high nutrient regions and a wide distribution of certain dissolved vitamins in the surface ocean. These measurements give us baseline data on the distribution of these metabolites and allow us to extend our understanding of microbial community activity in different regions of the ocean.

33 CFR 165.535 - Safety Zone: Atlantic Ocean, Vicinity of Cape Henlopen State Park, Delaware.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Safety Zone: Atlantic Ocean... Guard District § 165.535 Safety Zone: Atlantic Ocean, Vicinity of Cape Henlopen State Park, Delaware. (a) Location. The following area is a safety zone: All waters of the Atlantic Ocean within the area bounded by...

33 CFR 165.535 - Safety Zone: Atlantic Ocean, Vicinity of Cape Henlopen State Park, Delaware.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Safety Zone: Atlantic Ocean... Guard District § 165.535 Safety Zone: Atlantic Ocean, Vicinity of Cape Henlopen State Park, Delaware. (a) Location. The following area is a safety zone: All waters of the Atlantic Ocean within the area bounded by...

33 CFR 165.535 - Safety Zone: Atlantic Ocean, Vicinity of Cape Henlopen State Park, Delaware.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Safety Zone: Atlantic Ocean... Guard District § 165.535 Safety Zone: Atlantic Ocean, Vicinity of Cape Henlopen State Park, Delaware. (a) Location. The following area is a safety zone: All waters of the Atlantic Ocean within the area bounded by...

33 CFR 165.535 - Safety Zone: Atlantic Ocean, Vicinity of Cape Henlopen State Park, Delaware.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Safety Zone: Atlantic Ocean... Guard District § 165.535 Safety Zone: Atlantic Ocean, Vicinity of Cape Henlopen State Park, Delaware. (a) Location. The following area is a safety zone: All waters of the Atlantic Ocean within the area bounded by...

33 CFR 165.535 - Safety Zone: Atlantic Ocean, Vicinity of Cape Henlopen State Park, Delaware.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Safety Zone: Atlantic Ocean... Guard District § 165.535 Safety Zone: Atlantic Ocean, Vicinity of Cape Henlopen State Park, Delaware. (a) Location. The following area is a safety zone: All waters of the Atlantic Ocean within the area bounded by...

75 FR 20980 - Proposed Information Collection; Comment Request; Atlantic Surfclam and Ocean Quahog Framework...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-22

..., evaluate, and enforce fishery regulations. Framework Adjustment 1 (FW1) to the Atlantic Surf Clam and Ocean... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration Proposed Information Collection; Comment Request; Atlantic Surfclam and Ocean Quahog Framework Adjustment I AGENCY: National...

75 FR 19356 - Proposed Information Collection; Comment Request; Atlantic Surfclam and Ocean Quahog Framework...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-14

..., evaluate, and enforce fishery regulations. Framework Adjustment 1 (FW1) to the Atlantic Surf Clam and Ocean... DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration Proposed Information Collection; Comment Request; Atlantic Surfclam and Ocean Quahog Framework Adjustment I AGENCY: National...

Turbidity distribution in the Atlantic Ocean

USGS Publications Warehouse

Eittreim, S.; Thorndike, E.M.; Sullivan, L.

1976-01-01

The regional coverage of Lamont nephelometer data in the North and South Atlantic can be used to map seawater turbidity at all depths. At the level of the clearest water, in the mid-depth regions, the turbidity distribution primarily reflects the pattern of productivity in the surface waters. This suggests that the 'background' turbidity level in the oceans is largely a function of biogenic fallout. The bottom waters of the western Atlantic generally exhibit large increases in turbidity. The most intense benthic nepheloid layers are in the southwestern Argentine basin and northern North American basin; the lowest bottom water turbidity in the western Atlantic is in the equatorial regions. Both the Argentine and North American basin bottom waters appear to derive their high turbidity largely from local resuspension of terrigenous input in these basins. In contrast to the west, the eastern Atlantic basins show very low turbidities with the exception of three regions: the Mediterranean outflow area, the Cape basin, and the West European basin. ?? 1976.

Atlantic Ocean Circulation and Climate: The Current View From the Geological Record

NASA Astrophysics Data System (ADS)

Curry, W.

2006-12-01

Several recent advances in our understanding of past ocean circulation come from geological reconstructions using deep sea sediment proxies of water mass structure and flow. Put together, the observations suggest that the Atlantic Ocean during the last glacial period (21,000 years ago) was very different from today. Geochemical tracers document a shoaling of North Atlantic Deep Water and a much greater volume of deep waters with an Antarctic origin. Sedimentary pore water profiles have detected a reversal in the salinity gradient between northern and southern deep water sources. Uranium-series decay products in North Atlantic sediments indicate that the southward transport of North Atlantic Deep Water was as much as 30-40% reduced from today's transport. Ocean-margin density reconstructions are consistent with a one third reduction in transport through the Florida Straits. A reversed cross-basin density gradient in the South Atlantic calls for a different intermediate water circulation in the South Atlantic. The glacial Atlantic circulation appears to be best explained by a reduced influence of North Atlantic deep water sources and much greater influence of Antarctic deep water sources. More recent changes in Atlantic circulation have been much more modest. During the Little Ice Age (LIA - a much smaller cooling event about 200 to 600 years ago), transport of the Florida Current was reduced by about 10%, significant but a much smaller reduction than observed during the glacial period. There is little evidence for a change in the distribution or geochemistry of the water masses during the LIA. For both climate events (the glacial and the LIA) reduced Florida Current transport was accompanied by increased salinity of its surface waters, linking changes in ocean circulation to large scale changes in surface water hydrology. A feedback between the circulation of the Atlantic Ocean and the climate of the tropics has been proposed before and also seen in some coupled

Atlantic Induced Pan-tropical Climate Variability in the Upper-ocean and Atmosphere

NASA Astrophysics Data System (ADS)

Li, X.; Xie, S. P.; Gille, S. T.; Yoo, C.

2016-02-01

During the last three decades, tropical sea surface temperature (SST) exhibited dipole-like trends, with warming over the tropical Atlantic and Indo-Western Pacific but cooling over the Eastern Pacific. The Eastern Pacific cooling has recently been identified as a driver of the global warming hiatus. Previous studies revealed atmospheric bridges between the tropical Pacific, Atlantic, and Indian Ocean, which could potentially contribute to this zonally asymmetric SST pattern. However, the mechanisms and the interactions between these teleconnections remain unclear. To investigate these questions, we performed a `pacemaker' simulation by restoring the tropical Atlantic SST changes in a state-of-the-art climate model - the CESM1. Results show that the Atlantic plays a key role in initiating the tropical-wide teleconnections, and the Atlantic-induced anomalies contribute 55%-75% of the total tropical SST and circulation changes during the satellite era. A hierarchy of oceanic and atmospheric models are then used to investigate the physical mechanisms of these teleconnections: the Atlantic warming enhances atmospheric deep convection, drives easterly wind anomalies over the Indo-Western Pacific through the Kelvin wave, and westerly anomalies over the eastern Pacific as Rossby waves, in line with Gill's solution (Fig1a). These wind changes induce an Indo-Western Pacific warming via the wind-evaporation-SST effect, and this warming intensifies the La Niña-type response in the upper Pacific Ocean by enhancing the easterly trade winds and through the Bjerknes ocean-dynamical processes (Fig1b). The teleconnection finally develops into a tropical-wide SST dipole pattern with an enhanced trade wind and Walker circulation, similar as the observed changes during the satellite era. This mechanism reveals that the tropical ocean basins are more tightly connected than previously thought, and the Atlantic plays a key role in the tropical climate pattern formation and further the

Ocean array alters view of Atlantic conveyor

NASA Astrophysics Data System (ADS)

Kornei, Katherine

2018-02-01

Oceanographers have put a stethoscope on the coursing circulatory system of the Atlantic Ocean, and they have found a skittish pulse that's surprisingly strong in the waters east of Greenland—discoveries that should improve climate models. The powerful currents known as the Atlantic meridional overturning circulation (AMOC) are an engine in Earth's climate. The AMOC's shallower limbs—which include the Gulf Stream—move warm water from the tropics northward, warming Western Europe. In the north, the waters cool and sink, forming deeper limbs that transport the cold water back south—and sequester anthropogenic carbon in the process. Last week, at the American Geophysical Union's Ocean Sciences meeting, scientists presented the first data from an array of instruments moored in the subpolar North Atlantic, a $35 million, seven-nation project known as the Overturning in the Subpolar North Atlantic Program (OSNAP). Since 2004, researchers have gathered data from another array, at 26°N, stretching from Florida to Africa. But OSNAP is the first to monitor the circulation farther north, where a critical aspect of the overturning occurs. The observations reveal unexpected eddies and strong variability in the AMOC currents. They also show that the currents east of Greenland contribute the most to the total AMOC flow. Climate models, on the other hand, have emphasized the currents west of Greenland in the Labrador Sea.

Dynamics of upwelling annual cycle in the equatorial Atlantic Ocean

NASA Astrophysics Data System (ADS)

Wang, Li-Chiao; Jin, Fei-Fei; Wu, Chau-Ron; Hsu, Huang-Hsiung

2017-04-01

The annual upwelling is an important component of the equatorial Atlantic annual cycle. A simple theory is proposed using the framework of Zebiak-Cane (ZC) ocean model for insights into the dynamics of the upwelling annual cycle. It is demonstrated that in the Atlantic equatorial region this upwelling is dominated by Ekman processing in the west, whereas in the east it is primarily owing to shoaling and deepening of the thermocline resulting from equatorial mass meridional recharge/discharge and zonal redistribution processes associated with wind-driven equatorial ocean waves. This wind-driven wave upwelling plays an important role in the development of the annual cycle in the sea surface temperature of the cold tongue in the eastern equatorial Atlantic.

Long-term variations of SST and heat content in the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Huonsou-gbo, Aubains; Servain, Jacques; Caniaux, Guy; Araujo, Moacyr; Bourlès, Bernard; Veleda, Doris

2015-04-01

Recent studies (eg. Wen et al. 2010; Servain et al. 2014) suggest that subsurface processes influence the interannual variability of sea surface temperature (SST) in the tropical Atlantic through the Meridional Overturning Circulation (MOC) with time lags of several months. In this study, we used observed SST and Ocean heat content to test such hypothesis during the period 1964-2013. First results indicate great similarities in the positive linear trends of monthly standardized anomalies of SST, upper ocean heat content (0-500m) and deeper ocean heat content (500-2000m) averaged over the whole Atlantic Ocean. Strong positive trends of SST and deeper heat content occurred in the equatorial Atlantic, while a strong positive trend of the upper heat content was observed in the northeast Atlantic. These positive trends were the highest during the last two decades. The lagged positive correlation patterns between upper heat content anomalies over the whole gridded Atlantic Ocean and SST anomalies averaged over the equatorial region (60°W-15°E; 10°N-10°S) show a slow temporal evolution, which is roughly in agreement with the upper MOC. More detailed works about the mechanism, as well as about the origin of the highest positive trend of the deeper heat content in the equatorial region, are presently under investigation. References Servain J., G. Caniaux, Y. K. Kouadio, M. J. McPhaden, M. Araujo (2014). Recent climatic trends in the tropical Atlantic. Climate Dynamics, Vol. 43, 3071-3089, DOI 10.1007/s00382-014-2168-7.

Oxygen minimum zones in the eastern tropical Atlantic and Pacific oceans

NASA Astrophysics Data System (ADS)

Karstensen, Johannes; Stramma, Lothar; Visbeck, Martin

2008-06-01

Within the eastern tropical oceans of the Atlantic and Pacific basin vast oxygen minimum zones (OMZ) exist in the depth range between 100 and 900 m. Minimum oxygen values are reached at 300-500 m depth which in the eastern Pacific become suboxic (dissolved oxygen content <4.5 μmol kg -1) with dissolved oxygen concentration of less than 1 μmol kg -1. The OMZ of the eastern Atlantic is not suboxic and has relatively high oxygen minimum values of about 17 μmol kg -1 in the South Atlantic and more than 40 μmol kg -1 in the North Atlantic. About 20 (40%) of the North Pacific volume is occupied by an OMZ when using 45 μmol kg -1 (or 90 μmol kg -1, respectively) as an upper bound for OMZ oxygen concentration for ocean densities lighter than σθ < 27.2 kg m -3. The relative volumes reduce to less than half for the South Pacific (7% and 13%, respectively). The abundance of OMZs are considerably smaller (1% and 7%) for the South Atlantic and only ∼0% and 5% for the North Atlantic. Thermal domes characterized by upward displacements of isotherms located in the northeastern Pacific and Atlantic and in the southeastern Atlantic are co-located with the centres of the OMZs. They seem not to be directly involved in the generation of the OMZs. OMZs are a consequence of a combination of weak ocean ventilation, which supplies oxygen, and respiration, which consumes oxygen. Oxygen consumption can be approximated by the apparent oxygen utilization (AOU). However, AOU scaled with an appropriate consumption rate (aOUR) gives a time, the oxygen age. Here we derive oxygen ages using climatological AOU data and an empirical estimate of aOUR. Averaging oxygen ages for main thermocline isopycnals of the Atlantic and Pacific Ocean exhibit an exponential increase with density without an obvious signature of the OMZs. Oxygen supply originates from a surface outcrop area and can also be approximated by the turn-over time, the ratio of ocean volume to ventilating flux. The turn-over time

33 CFR 110.182 - Atlantic Ocean off Fort George Inlet, near Mayport, Fla.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Atlantic Ocean off Fort George Inlet, near Mayport, Fla. 110.182 Section 110.182 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Anchorage Grounds § 110.182 Atlantic Ocean...

33 CFR 110.182 - Atlantic Ocean off Fort George Inlet, near Mayport, Fla.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Atlantic Ocean off Fort George Inlet, near Mayport, Fla. 110.182 Section 110.182 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Anchorage Grounds § 110.182 Atlantic Ocean...

33 CFR 110.182 - Atlantic Ocean off Fort George Inlet, near Mayport, Fla.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Atlantic Ocean off Fort George Inlet, near Mayport, Fla. 110.182 Section 110.182 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Anchorage Grounds § 110.182 Atlantic Ocean...

33 CFR 110.182 - Atlantic Ocean off Fort George Inlet, near Mayport, Fla.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Atlantic Ocean off Fort George Inlet, near Mayport, Fla. 110.182 Section 110.182 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Anchorage Grounds § 110.182 Atlantic Ocean...

33 CFR 110.182 - Atlantic Ocean off Fort George Inlet, near Mayport, Fla.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Atlantic Ocean off Fort George Inlet, near Mayport, Fla. 110.182 Section 110.182 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Anchorage Grounds § 110.182 Atlantic Ocean...

76 FR 56322 - Atlantic Surfclam and Ocean Quahog Fisheries; 2012 Fishing Quotas for Atlantic Surfclams and...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-13

.... 101013504-0610-02] RIN 0648-XA529 Atlantic Surfclam and Ocean Quahog Fisheries; 2012 Fishing Quotas for.... ACTION: Temporary rule. SUMMARY: NMFS suspends the minimum size limit for Atlantic surfclams for the 2012... 2012 will remain status quo. Regulations governing these fisheries require NMFS to notify the public in...

A Possible Cause for Recent Decadal Atlantic Meridional Overturning Circulation Decline

NASA Astrophysics Data System (ADS)

Latif, Mojib; Park, Taewook; Park, Wonsun

2017-04-01

The Atlantic Meridional Overturning Circulation (AMOC) is a major oceanic current system with widespread climate impacts. AMOC influences have been discussed among others with regard to Atlantic hurricane activity, regional sea level variability, and surface air temperature and precipitation changes on land areas adjacent to the North Atlantic Ocean. Most climate models project significant AMOC slowing during the 21st century, if atmospheric greenhouse gas concentrations continue to rise unabatedly. Recently, a marked decadal decline in AMOC strength has been observed, which was followed by strongly reduced oceanic poleward heat transport and record low sea surface temperature in parts of the North Atlantic. Here, we provide evidence from observations, re-analyses and climate models that the AMOC decline was due to the combined action of the North Atlantic Oscillation and East Atlantic Pattern, the two leading modes of North Atlantic atmospheric surface pressure variability, which prior to the decline both transitioned into their negative phases. This change in atmospheric circulation diminished oceanic heat loss over the Labrador Sea and forced ocean circulation changes lowering upper ocean salinity transport into that region. As a consequence, Labrador Sea deep convection weakened, which eventually slowed the AMOC. This study suggests a new mechanism for decadal AMOC variability, which is important to multiyear climate predictability and climate change detection in the North Atlantic sector.

Hurricane Gonzalo in the Atlantic Ocean

NASA Image and Video Library

2017-12-08

On Oct. 16 at 17:45 UTC NASA's Terra satellite captured this image of Hurricane Gonzalo in the Atlantic Ocean. Image Credit: NASA Goddard MODIS Rapid Response Team-- NASA and NOAA satellites have been providing continuous coverage of Hurricane Gonzalo as it moves toward Bermuda. NASA's Terra satellite saw thunderstorms wrapped tightly around the center with large bands of thunderstorms wrapping into it. NOAA's GOES-East satellite provided and "eye-opening" view of Gonzalo, still a Category 4 hurricane on Oct. 16. A hurricane warning is in effect for Bermuda and that means that hurricane conditions are expected within the warning area, meaning the entire island. Read more: www.nasa.gov/content/goddard/gonzalo-atlantic-ocean/index... NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Eocene Temperature Evolution of the Tropical Atlantic Ocean

NASA Astrophysics Data System (ADS)

Cramwinckel, M.; Kocken, I.; Agnini, C.; Huber, M.; van der Ploeg, R.; Frieling, J.; Bijl, P.; Peterse, F.; Roehl, U.; Bohaty, S. M.; Schouten, S.; Sluijs, A.

2016-12-01

The transition from the early Eocene ( 50 Ma) hothouse towards the Oligocene ( 33 Ma) icehouse was interrupted by the Middle Eocene Climatic Optimum (MECO) ( 40 Ma), a 500,000-year long episode of deep sea and Southern Ocean warming. It remains unclear whether this transient warming event was global, and whether it was caused by changes in atmospheric greenhouse gas concentrations or confined to high latitudes resulting from ocean circulation change. Here we show, based on biomarker paleothermometry applied at Ocean Drilling Program Site 959, offshore Ghana, that sea surface temperatures in the eastern equatorial Atlantic Ocean declined by 7°C over the middle-late Eocene, in agreement with temperature trends documented in the southern high latitudes. In the equatorial Atlantic, this long-term trend was punctuated by 2.5°C warming during the MECO. At the zenith of MECO warmth, changes in dinoflagellate cyst assemblages and laminated sediments at Site 959 point to open ocean hyperstratification and seafloor deoxygenation, respectively. Remarkably, the data reveal that the magnitude of temperature change in the tropics was approximately half that in the Southern Ocean. This suggests that the generally ice free Eocene yielded limited but significant polar amplification of climate change. Crucially, general circulation model (GCM) simulations reveal that the recorded tropical and deep ocean temperature trends are best explained by greenhouse gas forcing, controlling both middle-late Eocene cooling and the superimposed MECO warming.

Why Do Organisms in the Atlantic Ocean Produce So Much CaCO3?

NASA Astrophysics Data System (ADS)

Toggweiler, J. R.

2010-12-01

Sediments in the Atlantic are richer in CaCO3 than sediments in the other oceans. Sediment trap observations show that sinking particles in the Atlantic also tend to have more CaCO3 in relation to organic carbon than sinking particles elsewhere. The reason for the extra production of CaCO3 has never been very clear. The Atlantic is unusual because it receives much more than its share of the global input of river water. River water adds alkalinity to the surface ocean while the production of CaCO3 takes it away. In this presentation a new tracer, called Alk*, is derived from the surface alkalinity distribution to highlight the impact of river inputs and the production of CaCO3. If the production of CaCO3 were evenly distributed across the ocean one would expect the Atlantic to have a higher level of Alk* becaused of its river inputs. We find instead that Alk* is lower in the middle of the Atlantic than almost any place else. This, of course, is consistent with the fact that organisms in the Atlantic produce a lot of CaCO3. Comparison with other areas with especially low values of Alk* (Red Sea and northern Arabian Sea) shows that the production of CaCO3 is highly correlated across the ocean with the surface salinity. Hence, we argue that organisms in the Atlantic produce a lot of CaCO3 simply because the Atlantic is so salty. Salty waters, by definition, have more CO3= ions, which increase the supersaturation with respect to calcite and aragonite. This finding, while extremely simple, has major implifications for the impact of ocean acidification on calcifying organisms.

Response of North Atlantic Ocean Chlorophyll a to the Change of Atlantic Meridional Overturning Circulation

NASA Astrophysics Data System (ADS)

Zhang, Min; Zhang, Yuanling; Shu, Qi; Zhao, Chang; Wang, Gang; Wu, Zhaohua; Qiao, Fangli

2017-04-01

Changes in marine phytoplankton are a vital component in global carbon cycling. Despite this far-reaching importance, the variable trend in phytoplankton and its response to climate variability remain unclear. This work presents the spatiotemporal evolution of the chlorophyll a trend in the North Atlantic Ocean by using merged ocean color products for the period 1997-2016. We find a dipole pattern between the subpolar gyre and the Gulf Stream path,and chlorophyll a trend signal propagatedalong the opposite direction of the North Atlantic Current. Such a dipole pattern and opposite propagation of chlorophyll a signal are consistent with the recent distinctive signature of the slowdown of the Atlantic MeridionalOverturning Circulation (AMOC). It is suggested that the spatiotemporal evolution of chlorophyll a during the two most recent decades is a part of the multidecadal variation and regulated byAMOC, which could be used as an indicator of AMOC variations.

Optimizing and Enhancing the Integrated Atlantic Ocean Observing System to enhance the societal, scientific and economic benefit

NASA Astrophysics Data System (ADS)

Reitz, Anja; Karstensen, Johannes; Visbeck, Martin; AtlantOS Consortium, the

2017-04-01

Atlantic Ocean observation is currently undertaken through loosely-coordinated, in-situ observing networks, satellite observations and data management arrangements of heterogeneous international, national and regional design to support science and a wide range of information products. Thus there is tremendous opportunity to develop the systems towards a fully integrated Atlantic Ocean Observing System consistent with the recently developed 'Framework of Ocean Observing'. The vision of AtlantOS is to improve and innovate Atlantic Ocean observing by establishing an international, more sustainable, more efficient, more integrated, and fit-for-purpose system. Hence, the EU Horizon 2020 project AtlantOS with its 62 partners from 18 countries (European and international) and several members will have a long-lasting and sustainable contribution to the societal, economic and scientific benefit by supporting the full cycle of the integrated ocean observation value chain from requirements via data gathering and observation, product generation, information, prediction, dissemination and stakeholder dialogue towards information and product provision. The benefits will be delivered by improving the value for money, extent, completeness, quality and ease of access to Atlantic Ocean data required by industries, product supplying agencies, scientist and citizens. The overarching target of the AtlantOS initiative is to deliver an advanced framework for the development of an integrated Atlantic Ocean Observing System that goes beyond the state-of -the-art, and leaves a legacy of sustainability after the life of the project. The legacy will derive from the following aims: i) to improve international collaboration in the design, implementation and benefit sharing of ocean observing, ii) to promote engagement and innovation in all aspects of ocean observing, iii) to facilitate free and open access to ocean data and information, iv) to enable and disseminate methods of achieving quality

Monitoring the North Atlantic using ocean colour data

NASA Astrophysics Data System (ADS)

Fuentes-Yaco, C.; Caverhill, C.; Maass, H.; Porter, C.; White, GN, III

2016-04-01

The Remote Sensing Unit (RSU) at the Bedford Institute of Oceanography (BIO) has been monitoring the North Atlantic using ocean colour products for decades. Optical sensors used include CZCS, POLDER, SeaWiFS, MODIS/Aqua and MERIS. The monitoring area is defined by the Atlantic Zone Monitoring Program (AZMP) but certain products extend into Arctic waters, and all-Canadian waters which include the Pacific coast. RSU provides Level 3 images for various products in several formats and a range of temporal and spatial resolutions. Basic statistics for pre-defined areas of interest are compiled for each product. Climatologies and anomaly maps are also routinely produced, and custom products are delivered by request. RSU is involved in the generation of Level 4 products, such as characterizing the phenology of spring and fall phytoplankton blooms, computing primary production, using ocean colour to aid in EBSA (Ecologically and Biologically Significant Area) definition and developing habitat suitability maps. Upcoming operational products include maps of diatom distribution, biogeochemical province boundaries, and products from sensors such as VIIRS (Visible Infrared Imaging Radiometer Suite), OLCI (Ocean Land Colour Instrument), and PACE (Pre-Aerosol, Clouds and ocean Ecosystem) hyperspectral microsatellite mission.

The North Atlantic Ocean Is in a State of Reduced Overturning

NASA Astrophysics Data System (ADS)

Smeed, D. A.; Josey, S. A.; Beaulieu, C.; Johns, W. E.; Moat, B. I.; Frajka-Williams, E.; Rayner, D.; Meinen, C. S.; Baringer, M. O.; Bryden, H. L.; McCarthy, G. D.

2018-02-01

The Atlantic Meridional Overturning Circulation (AMOC) is responsible for a variable and climatically important northward transport of heat. Using data from an array of instruments that span the Atlantic at 26°N, we show that the AMOC has been in a state of reduced overturning since 2008 as compared to 2004-2008. This change of AMOC state is concurrent with other changes in the North Atlantic such as a northward shift and broadening of the Gulf Stream and altered patterns of heat content and sea surface temperature. These changes resemble the response to a declining AMOC predicted by coupled climate models. Concurrent changes in air-sea fluxes close to the western boundary reveal that the changes in ocean heat transport and sea surface temperature have altered the pattern of ocean-atmosphere heat exchange over the North Atlantic. These results provide strong observational evidence that the AMOC is a major factor in decadal-scale variability of North Atlantic climate.

Dust Cloud, Mid Atlantic Ocean

NASA Technical Reports Server (NTRS)

1991-01-01

This view of a dust cloud from a Sahara Desert, North Africa dust storm was taken over the Mid Atlantic Ocean, some 1700 miles from the African coast (24.5N, 45.0W). Dust, sand and other particulate matter from arid regions is frequently stirred up by fast blowing desert winds and carried aloft to high altitudes where it may be transported great distances, sometimes as much as half way around the world.

Harmonising and semantically linking key variables from in-situ observing networks of an Integrated Atlantic Ocean Observing System, AtlantOS

NASA Astrophysics Data System (ADS)

Darroch, Louise; Buck, Justin

2017-04-01

Atlantic Ocean observation is currently undertaken through loosely-coordinated, in-situ observing networks, satellite observations and data management arrangements at regional, national and international scales. The EU Horizon 2020 AtlantOS project aims to deliver an advanced framework for the development of an Integrated Atlantic Ocean Observing System that strengthens the Global Ocean Observing System (GOOS) and contributes to the aims of the Galway Statement on Atlantic Ocean Cooperation. One goal is to ensure that data from different and diverse in-situ observing networks are readily accessible and useable to a wider community, including the international ocean science community and other stakeholders in this field. To help achieve this goal, the British Oceanographic Data Centre (BODC) produced a parameter matrix to harmonise data exchange, data flow and data integration for the key variables acquired by multiple in-situ AtlantOS observing networks such as ARGO, Seafloor Mapping and OceanSITES. Our solution used semantic linking of controlled vocabularies and metadata for parameters that were "mappable" to existing EU and international standard vocabularies. An AtlantOS Essential Variables list of terms (aggregated level) based on Global Climate Observing System (GCOS) Essential Climate Variables (ECV), GOOS Essential Ocean Variables (EOV) and other key network variables was defined and published on the Natural Environment Research Council (NERC) Vocabulary Server (version 2.0) as collection A05 (http://vocab.nerc.ac.uk/collection/A05/current/). This new vocabulary was semantically linked to standardised metadata for observed properties and units that had been validated by the AtlantOS community: SeaDataNet parameters (P01), Climate and Forecast (CF) Standard Names (P07) and SeaDataNet units (P06). Observed properties were mapped to biological entities from the internationally assured AphiaID from the WOrld Register of Marine Species (WoRMS), http

78 FR 70901 - Safety Zone; Bone Island Triathlon, Atlantic Ocean; Key West, FL

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-27

... 1625-AA00 Safety Zone; Bone Island Triathlon, Atlantic Ocean; Key West, FL AGENCY: Coast Guard, DHS... zone on the waters of the Atlantic Ocean in Key West, Florida, during the Bone Island Triathlon on... event. C. Discussion of Proposed Rule On January 25, 2014, Questor Multisport, LLC. is hosting the Bone...

77 FR 75853 - Safety Zone; Bone Island Triathlon, Atlantic Ocean; Key West, FL

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-26

...-AA00 Safety Zone; Bone Island Triathlon, Atlantic Ocean; Key West, FL AGENCY: Coast Guard, DHS. ACTION... Atlantic Ocean in Key West, Florida, during the Bone Island Triathlon on Saturday, January 12, 2013. The..., Questor Multisport, LLC is hosting the Bone Island Triathlon. The event will be held on the waters of the...

Centennial-scale links between Atlantic Ocean dynamics and hydroclimate over the last 4400 years: Insights from the northern Gulf of Mexico

NASA Astrophysics Data System (ADS)

Thirumalai, K.; Quinn, T. M.; Okumura, Y.; Richey, J. N.; Partin, J. W.; Poore, R. Z.

2015-12-01

Surface circulation in the Atlantic Ocean is an important mediator of global climate and yet its variability is poorly constrained on centennial timescales. Changes in the Atlantic meridional overturning circulation (AMOC) have been implicated in late Holocene climate variability in the Western Hemisphere, although the relationship between AMOC variability and hydroclimate is uncertain due to the lack of sufficiently highly resolved proxy records. Here we present a replicated reconstruction of sea-surface temperature (SST) and salinity (SSS) from the Garrison Basin in the northern Gulf of Mexico (NGOM) spanning the last 4,400 years to better constrain past sea-surface conditions. We generated time series of paired Mg/Ca (SST proxy) and δ18O (SST and SSS proxy) variations in planktic foraminifer Globigerinoides ruber (white variety) from three multi-cores collected in 2010. Using a Monte Carlo-based technique we produce a stacked record from the three multi-cores and constrain analytical, calibration, chronological, and sampling uncertainties. We apply this technique to existing paired Mg/Ca- δ18O studies in the Gulf of Mexico and Atlantic Ocean to facilitate comparison between time-uncertain proxy reconstructions. The Garrison Basin stack exhibits large centennial-scale variability (σSST~0.6°C; δ18Osw~0.17‰) and indicates a substantially cool (0.9±0.5°C) and fresh (0.26±0.1‰) Little Ice Age (LIA; 1450-1850 A.D.), corroborating extant records from the Gulf of Mexico. Focusing on the last millennium, we analyze a suite of oceanic and terrestrial proxy records to demonstrate a centennial-scale link between salt advection in the Atlantic Ocean, a diagnostic parameter of ocean circulation, and hydroclimate in the adjacent continents. The ensuing multiproxy relationships seem to be consistent with spatial field correlations of limited salinity and rainfall instrumental/reanalysis data, which suggest that NGOM salinity varies with large-scale Atlantic Ocean

Future change in ocean productivity: Is the Arctic the new Atlantic?

NASA Astrophysics Data System (ADS)

Yool, A.; Popova, E. E.; Coward, A. C.

2015-12-01

One of the most characteristic features in ocean productivity is the North Atlantic spring bloom. Responding to seasonal increases in irradiance and stratification, surface phytopopulations rise significantly, a pattern that visibly tracks poleward into summer. While blooms also occur in the Arctic Ocean, they are constrained by the sea-ice and strong vertical stratification that characterize this region. However, Arctic sea-ice is currently declining, and forecasts suggest this may lead to completely ice-free summers by the mid-21st century. Such change may open the Arctic up to Atlantic-style spring blooms, and do so at the same time as Atlantic productivity is threatened by climate change-driven ocean stratification. Here we use low and high-resolution instances of a coupled ocean-biogeochemistry model, NEMO-MEDUSA, to investigate productivity. Drivers of present-day patterns are identified, and changes in these across a climate change scenario (IPCC RCP 8.5) are analyzed. We find a globally significant decline in North Atlantic productivity (> -20%) by 2100, and a correspondingly significant rise in the Arctic (> +50%). However, rather than the future Arctic coming to resemble the current Atlantic, both regions are instead transitioning to a common, low nutrient regime. The North Pacific provides a counterexample where nutrients remain high and productivity increases with elevated temperature. These responses to climate change in the Atlantic and Arctic are common between model resolutions, suggesting an independence from resolution for key impacts. However, some responses, such as those in the North Pacific, differ between the simulations, suggesting the reverse and supporting the drive to more fine-scale resolutions. This article was corrected on 5 JAN 2016. See the end of the full text for details.

77 FR 43158 - Special Local Regulation; Battle on the Bay Powerboat Race Atlantic Ocean, Fire Island, NY

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-24

... 1625-AA08 Special Local Regulation; Battle on the Bay Powerboat Race Atlantic Ocean, Fire Island, NY... temporary special local regulation on the navigable waters of the Atlantic Ocean off Smith Point Park, Fire... on the Atlantic Ocean off Smith Point Park, Fire Island, NY and will feature six classes of offshore...

It is the time for oceanic seabirds: Tracking year-round distribution of gadfly petrels across the Atlantic Ocean

USGS Publications Warehouse

Ramos, Raul; Carlile, Nicholas; Madeiros, Jeremy; Ramirez, Ivan; Paiva, Vitor H.; Dinis, Herculano A.; Zino, Francis; Biscoito, Manuel; Leal, Gustavo R.; Bugoni, Leandro; Jodice, Patrick G.R.; Ryan, Peter G.; Gonzalez-Solis, Jacob

2017-01-01

AimAnthropogenic activities alter and constrain the structure of marine ecosystems with implications for wide-ranging marine vertebrates. In spite of the environmental importance of vast oceanic ecosystems, most conservation efforts mainly focus on neritic areas. To identify relevant oceanic areas for conservation, we assessed the year-round spatial distribution and spatio-temporal overlap of eight truly oceanic seabird species of gadfly petrels (Pterodroma spp.) inhabiting the Atlantic Ocean.LocationAtlantic Ocean.MethodsUsing tracking data (mostly from geolocators), we examined year-round distributions, the timing of life-cycle events, and marine habitat overlap of eight gadfly petrel species that breed in the Atlantic Ocean.ResultsWe compiled 125 year-round tracks. Movement strategies ranged from non-migratory to long-distance migrant species and from species sharing a common non-breeding area to species dispersing among multiple non-breeding sites. Gadfly petrels occurred throughout the Atlantic Ocean but tended to concentrate in subtropical regions. During the boreal summer, up to three species overlapped spatio-temporally over a large area around the Azores archipelago. During the austral summer, up to four species coincided in a core area in subtropical waters around Cape Verde, and three species shared habitat over two distinct areas off Brazil. The petrels used many national Exclusive Economic Zones, although they also exploited offshore international waters.Main conclusionsTracking movements of highly mobile vertebrates such as gadfly petrels can provide a powerful tool to evaluate and assess the potential need for and location of protected oceanic areas. As more multispecies, year-round data sets are collected from wide-ranging vertebrates, researchers and managers will have greater insight into the location of biodiversity hotspots. These can subsequently inform and guide marine spatial planning efforts that account for both conservation and

The Atlantic Multidecadal Oscillation without a role for ocean circulation.

PubMed

Clement, Amy; Bellomo, Katinka; Murphy, Lisa N; Cane, Mark A; Mauritsen, Thorsten; Rädel, Gaby; Stevens, Bjorn

2015-10-16

The Atlantic Multidecadal Oscillation (AMO) is a major mode of climate variability with important societal impacts. Most previous explanations identify the driver of the AMO as the ocean circulation, specifically the Atlantic Meridional Overturning Circulation (AMOC). Here we show that the main features of the observed AMO are reproduced in models where the ocean heat transport is prescribed and thus cannot be the driver. Allowing the ocean circulation to interact with the atmosphere does not significantly alter the characteristics of the AMO in the current generation of climate models. These results suggest that the AMO is the response to stochastic forcing from the mid-latitude atmospheric circulation, with thermal coupling playing a role in the tropics. In this view, the AMOC and other ocean circulation changes would be largely a response to, not a cause of, the AMO. Copyright © 2015, American Association for the Advancement of Science.

75 FR 34929 - Safety Zones: Neptune Deep Water Port, Atlantic Ocean, Boston, MA

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-21

...-AA00 Safety Zones: Neptune Deep Water Port, Atlantic Ocean, Boston, MA AGENCY: Coast Guard, DHS. ACTION..., Boston, MA; Final Rule (USCG-2009-0589), to protect vessels from the hazard posed by the presence of the... read as follows: Sec. 165.T01-0542 Safety Zones: Neptune Deepwater Port, Atlantic Ocean, Boston, MA. (a...

An alternative early opening scenario for the Central Atlantic Ocean

NASA Astrophysics Data System (ADS)

Labails, Cinthia; Olivet, Jean-Louis; Aslanian, Daniel; Roest, Walter R.

2010-09-01

The opening of the Central Atlantic Ocean basin that separated North America from northwest Africa is well documented and assumed to have started during the Late Jurassic. However, the early evolution and the initial breakup history of Pangaea are still debated: most of the existing models are based on one or multiple ridge jumps at the Middle Jurassic leaving the oldest crust on the American side, between the East Coast Magnetic Anomaly (ECMA) and the Blake Spur Magnetic Anomaly (BSMA). According to these hypotheses, the BSMA represents the limit of the initial basin and the footprint subsequent to the ridge jump. Consequently, the evolution of the northwest African margin is widely different from the northeast American margin. However, this setting is in contradiction with the existing observations. In this paper, we propose an alternative scenario for the continental breakup and the Mesozoic spreading history of the Central Atlantic Ocean. The new model is based on an analysis of geophysical data (including new seismic lines, an interpretation of the newly compiled magnetic data, and satellite derived gravimetry) and recently published results which demonstrate that the opening of the Central Atlantic Ocean started already during the Late Sinemurian (190 Ma), based on a new identification of the African conjugate to the ECMA and on the extent of salt provinces off Morocco and Nova Scotia. The identification of an African conjugate magnetic anomaly to BSMA, the African Blake Spur Magnetic Anomaly (ABSMA), together with the significant change in basement topography, are in good agreement with that initial reconstruction. The early opening history for the Central Atlantic Ocean is described in four distinct phases. During the first 20 Myr after the initial breakup (190-170 Ma, from Late Sinemurian to early Bajocian), oceanic accretion was extremely slow (˜ 0.8 cm/y). At the time of Blake Spur (170 Ma, early Bajocian), a drastic change occurred both in the relative

The relationship between cadmium and phosphate in the Atlantic Ocean unravelled

NASA Astrophysics Data System (ADS)

Middag, Rob; van Heuven, Steven M. A. C.; Bruland, Kenneth W.; de Baar, Hein J. W.

2018-06-01

Cadmium (Cd) is not generally considered a nutrient element, but behaves like a nutrient in the oceans and might play an important role in ocean biology after all. The relationship between Cd and the nutrient phosphate (PO4) has been studied for over 40 yrs, but the debate on the driving mechanism and reason behind the 'kink', a change in the steepness of the slope is ongoing. Using new data of high accuracy and spatial resolution covering the West-Atlantic Ocean from north to south, in combination with a robust extended optimum multiparameter (eOMP) water mass model, we show that mixing between different water masses is the dominant factor explaining the observed correlation and its kink. Regeneration of Cd via remineralisation explains the smaller scale variability, notably in the surface ocean. Observations imply the availability of Cd in surface waters determines the Cd-uptake and thus the Cd:PO4 remineralisation ratio. This ratio is variable between different ocean regions, notably between the northern and southern high latitude oceans. Due to their role in deep water formation, both the northern and southern high latitude oceans are a driving factor in the Atlantic and global Cd and PO4 relation. Outside the Atlantic Ocean, the classical kink is not expected, but the relationship is by no means linear. Most likely, this is due to the interaction between low latitude surface waters and subsurface waters from high latitude origin, but more data are required to assess this in detail.

Centennial- to millennial-scale ice-ocean interactions in the subpolar northeast Atlantic 18-41 kyr ago

NASA Astrophysics Data System (ADS)

Hall, I. R.; Colmenero-Hidalgo, E.; Zahn, R.; Peck, V. L.; Hemming, S. R.

2011-06-01

In order to monitor the evolution of the British-Irish Ice Sheet (BIIS) and its influence in surface ocean structure during marine isotopic stages (MIS) 2 and 3, we have analyzed the sediments recovered in core MD04-2829CQ (Rosemary Bank, north Rockall Trough, northeast Atlantic) dated between ˜41 and ˜18 ka B.P. Ice-rafted debris flux and composition, 40Ar/39Ar ages of individual hornblende grains, multispecies planktonic stable isotope records, planktonic foraminifera assemblage data and faunal-based sea surface temperatures (SSTs) demonstrate a close interaction between BIIS dynamics and surface ocean structure and water properties in this region. The core location lies beneath the North Atlantic Current (NAC) and is ideal for monitoring the shifts in the position of its associated oceanic fronts, as recorded by faunal changes. These data reveal a succession of BIIS-sourced iceberg calving events related to low SST, usually synchronous with dramatic changes in the composition of the planktonic foraminifera assemblage and with variations in the stable isotope records of the taxa Neogloboquadrina pachyderma (sinistral coiling) and Globigerina bulloides. The pacing of the calving events, from typically Dansgaard-Oeschger millennial timescales during late MIS 3 to multicentennial cyclicity from ˜28 ka B.P., represents the build-up of the BIIS and its growing instability toward Heinrich Event (HE) 2 and the Last Glacial Maximum. Our data confirm the strong coupling between BIIS instabilities and the temperature and salinity of surface waters in the adjacent northeast Atlantic and demonstrate the BIIS's ability to modify the NAC on its flow toward the Nordic Seas. In contrast, subsurface water masses were less affected except during the Greenland stadials that contain HEs, when most intense water column reorganizations occurred simultaneously with the deposition of cream-colored carbonate sourced from the Laurentide Ice Sheet.

78 FR 57796 - Safety Zone; Pro Hydro-X Tour, Atlantic Ocean, Islamorada, FL

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-20

... 1625-AA00 Safety Zone; Pro Hydro-X Tour, Atlantic Ocean, Islamorada, FL AGENCY: Coast Guard, DHS... waters of the Atlantic Ocean, Islamorada, Florida during the Pro Hydro- X Tour. The Pro Hydro-X Tour is a... course for each race. The Pro Hydro-X Tour is scheduled to take place on September 20, 21, and 22, 2013...

Microplastic pollution in the Northeast Atlantic Ocean: validated and opportunistic sampling.

PubMed

Lusher, Amy L; Burke, Ann; O'Connor, Ian; Officer, Rick

2014-11-15

Levels of marine debris, including microplastics, are largely un-documented in the Northeast Atlantic Ocean. Broad scale monitoring efforts are required to understand the distribution, abundance and ecological implications of microplastic pollution. A method of continuous sampling was developed to be conducted in conjunction with a wide range of vessel operations to maximise vessel time. Transects covering a total of 12,700 km were sampled through continuous monitoring of open ocean sub-surface water resulting in 470 samples. Items classified as potential plastics were identified in 94% of samples. A total of 2315 particles were identified, 89% were less than 5mm in length classifying them as microplastics. Average plastic abundance in the Northeast Atlantic was calculated as 2.46 particles m(-3). This is the first report to demonstrate the ubiquitous nature of microplastic pollution in the Northeast Atlantic Ocean and to present a potential method for standardised monitoring of microplastic pollution. Copyright © 2014 Elsevier Ltd. All rights reserved.

78 FR 39995 - Safety Zone; Margate Mother's Association Fireworks Display, Atlantic Ocean; Margate, NJ

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-03

...-AA00 Safety Zone; Margate Mother's Association Fireworks Display, Atlantic Ocean; Margate, NJ AGENCY... launched from a barge with a fall out zone that covers part of the Atlantic Ocean. Margate Mother's..., Sector Delaware Bay, has determined that the Margate Mother's Association Fireworks Display will pose...

33 CFR 334.100 - Atlantic Ocean off Cape May, N.J.; Coast Guard Rifle Range.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Atlantic Ocean off Cape May, N.J.; Coast Guard Rifle Range. 334.100 Section 334.100 Navigation and Navigable Waters CORPS OF ENGINEERS... Ocean off Cape May, N.J.; Coast Guard Rifle Range. (a) The danger zone. The waters of the Atlantic Ocean...

33 CFR 334.100 - Atlantic Ocean off Cape May, N.J.; Coast Guard Rifle Range.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Atlantic Ocean off Cape May, N.J.; Coast Guard Rifle Range. 334.100 Section 334.100 Navigation and Navigable Waters CORPS OF ENGINEERS... Ocean off Cape May, N.J.; Coast Guard Rifle Range. (a) The danger zone. The waters of the Atlantic Ocean...

33 CFR 334.100 - Atlantic Ocean off Cape May, N.J.; Coast Guard Rifle Range.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false Atlantic Ocean off Cape May, N.J.; Coast Guard Rifle Range. 334.100 Section 334.100 Navigation and Navigable Waters CORPS OF ENGINEERS... Ocean off Cape May, N.J.; Coast Guard Rifle Range. (a) The danger zone. The waters of the Atlantic Ocean...

33 CFR 334.100 - Atlantic Ocean off Cape May, N.J.; Coast Guard Rifle Range.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Atlantic Ocean off Cape May, N.J.; Coast Guard Rifle Range. 334.100 Section 334.100 Navigation and Navigable Waters CORPS OF ENGINEERS... Ocean off Cape May, N.J.; Coast Guard Rifle Range. (a) The danger zone. The waters of the Atlantic Ocean...

33 CFR 334.100 - Atlantic Ocean off Cape May, N.J.; Coast Guard Rifle Range.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Atlantic Ocean off Cape May, N.J.; Coast Guard Rifle Range. 334.100 Section 334.100 Navigation and Navigable Waters CORPS OF ENGINEERS... Ocean off Cape May, N.J.; Coast Guard Rifle Range. (a) The danger zone. The waters of the Atlantic Ocean...

Patterns and Trends of Primary Production, Inorganic Carbon and Oxygen and Their Ecosystem Impacts in a Regional Biogeochemical Ocean Model for Atlantic Canada

NASA Astrophysics Data System (ADS)

Fennel, K.; Rutherford, K. E.; Kuhn, A. M.; Zhang, W.; Brennan, C. E.; Zhang, R.

2016-12-01

Representing coastal oceans in global biogeochemical models is a challenge, yet the ecosystems in these regions are most vulnerable to the combined stressors of ocean warming, deoxygenation, acidification, eutrophication and fishing. Coastal regions also have large air-sea fluxes of CO2, making them an important but poorly quantified component of the global carbon cycle, and are the most relevant for human activities. Regional model applications that are nested within large-scale or global models are necessary for detailed studies of coastal regions. We present results from such a regional biogeochemical model for the northwestern North Atlantic shelves and adjacent deep ocean of Atlantic Canada. The model is an implementation of the Regional Ocean Modeling System (ROMS) and includes an NPZD-type nitrogen cycle model with explicit representation of dissolved oxygen and inorganic carbon. The region is at the confluence of the Gulf Stream and Labrador Current making it highly dynamic, a challenge for analysis and prediction, and prone to large changes. Historically a rich fishing ground, coastal ecosystems in Atlantic Canada have undergone dramatic changes including the collapse of several economically important fish stocks and the listing of many species as threatened or endangered. Furthermore it is unclear whether the region is a net source or sink of atmospheric CO2 with estimates of the size and direction of the net air-sea CO2 flux remaining controversial. We will discuss simulated patterns of primary production, inorganic carbon fluxes and oxygen trends in the context of circulation features and shelf residence times for the present ocean state and present future projections.

Salinity Boundary Conditions and the Atlantic Meridional Overturning Circulation in Depth and Quasi-Isopycnic Coordinate Global Ocean Models

DTIC Science & Technology

2009-06-30

Atlantic Meridional Overturning Circulation in Depth and Quasi-Isopycnic Coordinate Global Ocean...2009 4. TITLE AND SUBTITLE Salinity Boundary Conditions and the Atlantic Meridional Overturning Circulation in Depth and Quasi-Isopycnic Coordinate... Atlantic Meridional Overturning Circulation (AMOC) in global simulations performed with the depth coordinate Parallel Ocean Program (POP) ocean

33 CFR 334.500 - St. Johns River, Atlantic Ocean, Sherman Creek; restricted areas and danger zone, Naval Station...

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false St. Johns River, Atlantic Ocean... AND RESTRICTED AREA REGULATIONS § 334.500 St. Johns River, Atlantic Ocean, Sherman Creek; restricted... area and the Atlantic Ocean restricted area described in paragraphs (a)(2) and (a)(3) of this section...

33 CFR 334.500 - St. Johns River, Atlantic Ocean, Sherman Creek; restricted areas and danger zone, Naval Station...

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false St. Johns River, Atlantic Ocean... AND RESTRICTED AREA REGULATIONS § 334.500 St. Johns River, Atlantic Ocean, Sherman Creek; restricted... area and the Atlantic Ocean restricted area described in paragraphs (a)(2) and (a)(3) of this section...

33 CFR 334.500 - St. Johns River, Atlantic Ocean, Sherman Creek; restricted areas and danger zone, Naval Station...

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false St. Johns River, Atlantic Ocean... AND RESTRICTED AREA REGULATIONS § 334.500 St. Johns River, Atlantic Ocean, Sherman Creek; restricted... area and the Atlantic Ocean restricted area described in paragraphs (a)(2) and (a)(3) of this section...

FERROMANGANESE CRUST RESOURCES IN THE PACIFIC AND ATLANTIC OCEANS.

USGS Publications Warehouse

Commeau, R.F.; Clark, A.; Johnson, Chad; Manheim, F.T.; Aruscavage, P. J.; Lane, C.M.

1984-01-01

Ferromanganese crusts on raised areas of the ocean floor have joined abyssal manganese nodules and hydrothermal sulfides as potential marine resources. Significant volumes of cobalt-rich (about 1% Co) crusts have been identified to date within the US Exclusive Economic Zone (EEZ) in the Central Pacific: in the NW Hawaiian Ridge and Seamount region and in the seamounts in the Johnston Island and Palmyra Island regions. Large volumes of lower grade crusts, slabs, and nodules are also present in shallow ( greater than 1000 m) waters on the Blake plateau, off Florida-South Carolina in the Atlantic Ocean. Data on ferromanganese crusts have been increased by recent German and USGS cruises, but are still sparse, and other regions having crust potential are under current investigation. The authors discuss economic potentials for cobalt-rich crusts in the Central Pacific and Western North Atlantic oceans, with special reference to US EEZ areas. Additional research is needed before more quantitative resource estimates can be made.

Otolith chemistry discriminates natal signatures of yellowfin tuna (Thunnus albacares) in the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Kitchens, L. L.; Rooker, J. R.

2016-02-01

In this study, the otolith chemistry of young-of-the-year (YOY) yellowfin tuna (Thunnus albacares) was examined to determine whether chemical signatures are distinct across different putative spawning areas in the Atlantic Ocean. Yellowfin tuna is a highly migratory species that is currently managed as a single panmictic stock in the Atlantic Ocean; however, uncertainty remains regarding the population structure of yellowfin in this region, particularly concerning the degree of mixing between spawning populations. Analysis of naturally occurring chemical tracers in otoliths provides a valuable means to reconstruct a fish's environmental history and is thus a promising approach for delineating stock structure of Atlantic yellowfin tuna. YOY yellowfin tuna otoliths were collected from 5 locations in the Atlantic Ocean (Gulf of Mexico, SE Caribbean, Brazil, Cape Verde, and Gulf of Guinea) from 2013-2015 and trace element (Li, Mg, Mn, Co, Cu, Sr, Zn, and Ba) and stable isotope (δ13C and δ18O) analyses were conducted to investigate regional variation in otolith chemical composition. Results show significant differences among nursery areas in both trace element (MANOVA, p<0.001) and δ13C and δ18O signatures (ANOVA, p=0.017 and p=0.001, respectively). Particularly high spatial separation was observed based on eastern Atlantic (Gulf of Guinea + Cape Verde) and western Atlantic (Gulf of Mexico + Brazil + Martinique) nursery areas, indicating the approach has promise for distinguishing migrants displaying trans-ocean movement. These chemical signatures will be used to assign adult yellowfin tuna to their nursery of origin, ultimately providing an improved understanding of the stock structure and movement of yellowfin tuna in the Atlantic Ocean.

Litter survey detects the South Atlantic 'garbage patch'.

PubMed

Ryan, Peter G

2014-02-15

A distance-based technique was used to assess the distribution and abundance of floating marine debris (>1cm) in the southeast Atlantic Ocean between Cape Town and Tristan da Cunha, crossing the southern edge of the South Atlantic 'garbage patch' predicted by surface drift models. Most litter was made of plastic (97%). Detection distances were influenced by the size and buoyancy of litter items. Litter density decreased from coastal waters off Cape Town (>100 items km(-2)) to oceanic waters (<10 items km(-2)), and was consistently higher (6.2 ± 1.3 items km(-2)) from 3 to 8°E than in adjacent oceanic waters (2.7 ± 0.3 items km(-2)) or in the central South Atlantic around Tristan (1.0 ± 0.4 items km(-2)). The area with high litter density had few seaweeds, suggesting that most litter had been drifting for a long time. The results indicate that floating debris is accumulating in the South Atlantic gyre as far south as 34-35°S. Copyright © 2013 Elsevier Ltd. All rights reserved.

Detection of Natural Oil Seeps in the Atlantic Ocean Using MODIS

NASA Technical Reports Server (NTRS)

Reahard, Ross; Jones, Jason B.; Mitchell, Mark

2010-01-01

Natural oil seepage is the release of crude oil into the ocean from fissures in the seabed. Oil seepage is a major contributor to the total amount of oil entering the world s oceans. According to a 2003 study by the National Academy of Sciences (NAS), 47 percent of oil entering the world s oceans is from natural seeps, and 53 percent is from human sources (extraction, transportation, and consumption). Oil seeps cause smooth oil slicks to form on the water s surface. Oil seeps can indicate the location of stores of fossil fuel beneath the ocean floor. Knowledge of the effect of oil seepage on marine life and marine ecosystems remains limited. In the past, remote sensing has been used to detect oil seeps in the Gulf of Mexico and off of the coast of southern California. This project utilized sun glint MODIS imagery to locate oil slicks off of the Atlantic coast, an area that had not previously been surveyed for natural oil seeps using remote sensing. Since 1982, the Atlantic Ocean has been closed to any oil and gas drilling. Recently, however, the U.S. Minerals Management Services (MMS) has proposed a lease for oil and gas drilling off the coasts of Virginia and North Carolina. Determining the location of seepage sites in the Atlantic Ocean will help MMS locate potential deposits of oil and natural gas, thereby reducing the risk of leasing areas for petroleum extraction that do not contain these natural resources.

77 FR 50019 - Safety Zone; Cocoa Beach Air Show, Atlantic Ocean, Cocoa Beach, FL

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-20

... 1625-AA00 Safety Zone; Cocoa Beach Air Show, Atlantic Ocean, Cocoa Beach, FL AGENCY: Coast Guard, DHS... waters of the Atlantic Ocean located east of Cocoa Beach, Florida during the Cocoa Beach Air Show. The Cocoa Beach Air Show will include aircraft engaging in aerobatic maneuvers. The event is scheduled to...

Shifting Surface Currents in the Northern North Atlantic Ocean

NASA Technical Reports Server (NTRS)

Hakkinen, Sirpa; Rhines, Peter B.

2007-01-01

Analysis of surface drifter tracks in the North Atlantic Ocean from the time period 1990 to 2006 provides the first evidence that the Gulf Stream waters can have direct pathways to the Nordic Seas. Prior to 2000, the drifters entering the channels leading to the Nordic Seas originated in the western and central subpolar region. Since 2001 several paths from the western subtropics have been present in the drifter tracks leading to the Rockall Trough through which the most saline North Atlantic Waters pass to the Nordic Seas. Eddy kinetic energy from altimetry shows also the increased energy along the same paths as the drifters, These near surface changes have taken effect while the altimetry shows a continual weakening of the subpolar gyre. These findings highlight the changes in the vertical structure of the northern North Atlantic Ocean, its dynamics and exchanges with the higher latitudes, and show how pathways of the thermohaline circulation can open up and maintain or increase its intensity even as the basin-wide circulation spins down.

The Low-Frequency Variability of the Tropical Atlantic Ocean

NASA Technical Reports Server (NTRS)

Haekkinen, Sirpa; Mo, Kingtse C.; Koblinsky, Chester J. (Technical Monitor)

2001-01-01

Upper ocean temperature variability in the tropical Atlantic is examined from the Comprehensive Ocean Atmosphere Data Set (COADS) as well as from an ocean model simulation forced by COADS anomalies appended to a monthly climatology. Our findings are as follows: Only the sea surface temperatures (SST) in the northern tropics are driven by heat fluxes, while the southern tropical variability arises from wind driven ocean circulation changes. The subsurface temperatures in the northern and southern tropics are found to have a strong linkage to buoyancy forcing changes in the northern North Atlantic. Evidence for Kelvin-like boundary wave propagation from the high latitudes is presented from the model simulation. This extratropical influence is associated with wintertime North Atlantic Oscillation (NAO) forcing and manifests itself in the northern and southern tropical temperature anomalies of the same sign at depth of 100-200 meters as result of a Rossby wave propagation away from the eastern boundary in the wake of the boundary wave passage. The most apparent association of the southern tropical sea surface temperature anomalies (STA) arises with the anomalous cross-equatorial winds which can be related to both NAO and the remote influence from the Pacific equatorial region. These teleconnections are seasonal so that the NAO impact on the tropical SST is the largest it mid-winter but in spring and early summer the Pacific remote influence competes with NAO. However, NAO appears to have a more substantial role than the Pacific influence at low frequencies during the last 50 years. The dynamic origin of STA is indirectly confirmed from the SST-heat flux relationship using ocean model experiments which remove either anomalous wind stress forcing or atmospheric forcing anomalies contributing to heat exchange.

77 FR 72762 - Atlantic Surfclam and Ocean Quahog Fisheries; 2013 Fishing Quotas for Atlantic Surfclams and...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-06

... Management Specialist, (978) 281-9177; fax (978) 281-9135. SUPPLEMENTARY INFORMATION: Section 648.72(c) of... (181 million L) for Atlantic surfclams, 5.333 million bu (284 million L) for ocean quahogs, and 100,000 Maine bu (3.524 million L) for Maine ocean quahogs, as announced in the Federal Register on December 27...

Arctic and N Atlantic Crustal Thickness and Oceanic Lithosphere Distribution from Gravity Inversion

NASA Astrophysics Data System (ADS)

Kusznir, Nick; Alvey, Andy

2014-05-01

The ocean basins of the Arctic and N. Atlantic formed during the Mesozoic and Cenozoic as a series of distinct ocean basins, both small and large, leading to a complex distribution of oceanic crust, thinned continental crust and rifted continental margins. The plate tectonic framework of this region was demonstrated by the pioneering work of Peter Ziegler in AAPG Memoir 43 " Evolution of the Arctic-North Atlantic and the Western Tethys" published in 1988. The spatial evolution of Arctic Ocean and N Atlantic ocean basin geometry and bathymetry are critical not only for hydrocarbon exploration but also for understanding regional palaeo-oceanography and ocean gateway connectivity, and its influence on global climate. Mapping crustal thickness and oceanic lithosphere distribution represents a substantial challenge for the Polar Regions. Using gravity anomaly inversion we have produced comprehensive maps of crustal thickness and oceanic lithosphere distribution for the Arctic and N Atlantic region, We determine Moho depth, crustal basement thickness, continental lithosphere thinning and ocean-continent transition location using a 3D spectral domain gravity inversion method, which incorporates a lithosphere thermal gravity anomaly correction (Chappell & Kusznir 2008). Gravity anomaly and bathymetry data used in the gravity inversion are from the NGA (U) Arctic Gravity Project and IBCAO respectively; sediment thickness is from a new regional compilation. The resulting maps of crustal thickness and continental lithosphere thinning factor are used to determine continent-ocean boundary location and the distribution of oceanic lithosphere. Crustal cross-sections using Moho depth from the gravity inversion allow continent-ocean transition structure to be determined and magmatic type (magma poor, "normal" or magma rich). Our gravity inversion predicts thin crust and high continental lithosphere thinning factors in the Eurasia, Canada, Makarov, Podvodnikov and Baffin Basins

Meridional overturning circulation conveys fast acidification to the deep Atlantic Ocean.

PubMed

Perez, Fiz F; Fontela, Marcos; García-Ibáñez, Maribel I; Mercier, Herlé; Velo, Anton; Lherminier, Pascale; Zunino, Patricia; de la Paz, Mercedes; Alonso-Pérez, Fernando; Guallart, Elisa F; Padin, Xose A

2018-02-22

Since the Industrial Revolution, the North Atlantic Ocean has been accumulating anthropogenic carbon dioxide (CO 2 ) and experiencing ocean acidification, that is, an increase in the concentration of hydrogen ions (a reduction in pH) and a reduction in the concentration of carbonate ions. The latter causes the 'aragonite saturation horizon'-below which waters are undersaturated with respect to a particular calcium carbonate, aragonite-to move to shallower depths (to shoal), exposing corals to corrosive waters. Here we use a database analysis to show that the present rate of supply of acidified waters to the deep Atlantic could cause the aragonite saturation horizon to shoal by 1,000-1,700 metres in the subpolar North Atlantic within the next three decades. We find that, during 1991-2016, a decrease in the concentration of carbonate ions in the Irminger Sea caused the aragonite saturation horizon to shoal by about 10-15 metres per year, and the volume of aragonite-saturated waters to reduce concomitantly. Our determination of the transport of the excess of carbonate over aragonite saturation ( xc [CO 3 2- ])-an indicator of the availability of aragonite to organisms-by the Atlantic meridional overturning circulation shows that the present-day transport of carbonate ions towards the deep ocean is about 44 per cent lower than it was in preindustrial times. We infer that a doubling of atmospheric anthropogenic CO 2 levels-which could occur within three decades according to a 'business-as-usual scenario' for climate change-could reduce the transport of xc [CO 3 2- ] by 64-79 per cent of that in preindustrial times, which could severely endanger cold-water coral habitats. The Atlantic meridional overturning circulation would also export this acidified deep water southwards, spreading corrosive waters to the world ocean.

Meridional overturning circulation conveys fast acidification to the deep Atlantic Ocean

NASA Astrophysics Data System (ADS)

Perez, Fiz F.; Fontela, Marcos; García-Ibáñez, Maribel I.; Mercier, Herlé; Velo, Anton; Lherminier, Pascale; Zunino, Patricia; de La Paz, Mercedes; Alonso-Pérez, Fernando; Guallart, Elisa F.; Padin, Xose A.

2018-02-01

Since the Industrial Revolution, the North Atlantic Ocean has been accumulating anthropogenic carbon dioxide (CO2) and experiencing ocean acidification, that is, an increase in the concentration of hydrogen ions (a reduction in pH) and a reduction in the concentration of carbonate ions. The latter causes the ‘aragonite saturation horizon’—below which waters are undersaturated with respect to a particular calcium carbonate, aragonite—to move to shallower depths (to shoal), exposing corals to corrosive waters. Here we use a database analysis to show that the present rate of supply of acidified waters to the deep Atlantic could cause the aragonite saturation horizon to shoal by 1,000-1,700 metres in the subpolar North Atlantic within the next three decades. We find that, during 1991-2016, a decrease in the concentration of carbonate ions in the Irminger Sea caused the aragonite saturation horizon to shoal by about 10-15 metres per year, and the volume of aragonite-saturated waters to reduce concomitantly. Our determination of the transport of the excess of carbonate over aragonite saturation (xc[CO32-])—an indicator of the availability of aragonite to organisms—by the Atlantic meridional overturning circulation shows that the present-day transport of carbonate ions towards the deep ocean is about 44 per cent lower than it was in preindustrial times. We infer that a doubling of atmospheric anthropogenic CO2 levels—which could occur within three decades according to a ‘business-as-usual scenario’ for climate change—could reduce the transport of xc[CO32-] by 64-79 per cent of that in preindustrial times, which could severely endanger cold-water coral habitats. The Atlantic meridional overturning circulation would also export this acidified deep water southwards, spreading corrosive waters to the world ocean.

Pathways of Atlantic Waters in the Nordic seas: locally eddy-permitting ocean simulation in a global setup

NASA Astrophysics Data System (ADS)

Wekerle, C.; Wang, Q.; Danilov, S.; Jung, T.; Schourup-Kristensen, V.

2016-02-01

Atlantic Water (AW) passes through the Nordic Seas and enters the Arctic Ocean through the shallow Barents Sea and the deep Fram Strait. Since the 1990's, observations indicate a series of anomalously warm pulses of Atlantic Water that entered the Arctic Ocean. In fact, poleward oceanic heat transport may even increase in the future, which might have implications for the heat uptake in the Arctic Ocean as well as for the sea ice cover. The ability of models to faithfully simulate the pathway of the AW and accompanying dynamics is thus of high climate relevance. In this study, we explore the potential of a global multi-resolution sea ice-ocean model with a locally eddy-permitting resolution (around 4.5 km) in the Nordic seas region and Arctic Ocean in improving the representation of Atlantic Water inflow, and more broadly, the dynamics of the circulation in the Northern North Atlantic and Arctic. The simulation covers the time period 1969-2009. We find that locally increased resolution improves the localization and thickness of the Atlantic Water layer in the Nordic seas, compared with a 20 km resolution reference simulation. In particular, the inflow of Atlantic Waters through the Greenland Scotland Ridge and the narrow branches of the Norwegian Atlantic Current can be realistically represented. Lateral spreading due to simulated eddies essentially reduces the bias in the surface temperature. In addition, a qualitatively good agreement of the simulated eddy kinetic energy field with observations can be achieved. This study indicates that a substantial improvement in representing local ocean dynamics can be reached through the local refinement, which requires a rather moderate computational effort. The successful model assessment allows us to further investigate the variability and mechanisms behind Atlantic Water transport into the Arctic Ocean.

Meridional Distribution of Aerosol Optical Thickness over the Tropical Atlantic Ocean

NASA Technical Reports Server (NTRS)

Kishcha, P.; Silva, Arlindo M.; Starobinets, B.; Long, C. N.; Kalashnikova, O.; Alpert, P.

2015-01-01

Previous studies showed that, over the global ocean, there is hemispheric asymmetry in aerosols and no noticeable asymmetry in cloud fraction (CF). In the current study, we focus on the tropical Atlantic (30 Deg N 30 Deg S) which is characterized by significant amounts of Saharan dust dominating other aerosol species over the North Atlantic. We found that, by contrast to the global ocean, over a limited area such as the tropical Atlantic, strong meridional asymmetry in dust aerosols was accompanied by meridional CF asymmetry. During the 10-year study period (July 2002 June 2012), NASA Aerosol Reanalysis (aka MERRAero) showed that, when the meridional asymmetry in dust aerosol optical thickness (AOT) was the most pronounced (particularly in July), dust AOT averaged separately over the tropical North Atlantic was one order of magnitude higher than dust AOT averaged over the tropical South Atlantic. In the presence of such strong meridional asymmetry in dust AOT in July, CF averaged separately over the tropical North Atlantic exceeded CF averaged over the tropical South Atlantic by 20%. Our study showed significant cloud cover, up to 0.8 - 0.9, in July along the Saharan Air Layer which contributed to above-mentioned meridional CF asymmetry. Both Multi-Angle Imaging SpectroRadiometer (MISR) measurements and MERRAero data were in agreement on seasonal variations in meridional aerosol asymmetry. Meridional asymmetry in total AOT over the Atlantic was the most pronounced between March and July, when dust presence over the North Atlantic was maximal. In September and October, there was no noticeable meridional asymmetry in total AOT and meridional CF distribution over the tropical Atlantic was almost symmetrical.

Streamflow from the United States into the Atlantic Ocean during 1931-1960

USGS Publications Warehouse

Bue, Conrad D.

1970-01-01

Streamflow from the United States into the Atlantic Ocean, between the international stream St. Croix River, inclusive, and Cape Sable, Fla., averaged about 355,000 cfs (cubic feet per second) during the 30-year period 1931-60, or roughly 20 percent of the water that, on the average flows out of the conterminous United States. The area drained by streams flowing into the Atlantic Ocean is about 288,000 square miles, including the Canadian part of the St. Croix and Connecticut River basins, or a little less than 10 percent of the area of the conterminous United States. Hence, the average streamflow into the Atlantic Ocean, in terms of cubic feet per second per square mile, is about twice the national average of the flow that leaves the conterminous United States. Flow from about three-fourths of the area draining into the Atlantic Ocean is gaged at streamflow measuring stations of the U.S. Geological Survey. The remaining one-fourth of the drainage area consists mostly of low-lying coastal areas from which the flow was estimated, largely on the basis of nearby gaging stations. Streamflow, in terms of cubic feet per second per square mile, decreases rather progressively from north to south. It averages nearly 2 cfs along the Maine coast, about 1 cfs along the North Carolina coast, and about 0.9 cfs along the Florida coast.

Genetic discontinuity among regional populations of Lophelia pertusa in the North Atlantic Ocean

USGS Publications Warehouse

Morrison, C.L.; Ross, Steve W.; Nizinski, M.S.; Brooke, S.; Jarnegren, J.; Waller, R.G.; Johnson, Robin L.; King, T.L.

2011-01-01

Knowledge of the degree to which populations are connected through larval dispersal is imperative to effective management, yet little is known about larval dispersal ability or population connectivity in Lophelia pertusa, the dominant framework-forming coral on the continental slope in the North Atlantic Ocean. Using nine microsatellite DNA markers, we assessed the spatial scale and pattern of genetic connectivity across a large portion of the range of L. pertusa in the North Atlantic Ocean. A Bayesian modeling approach found four distinct genetic groupings corresponding to ocean regions: Gulf of Mexico, coastal southeastern U.S., New England Seamounts, and eastern North Atlantic Ocean. An isolation-by-distance pattern was supported across the study area. Estimates of pairwise population differentiation were greatest with the deepest populations, the New England Seamounts (average F ST = 0.156). Differentiation was intermediate with the eastern North Atlantic populations (F ST = 0.085), and smallest between southeastern U.S. and Gulf of Mexico populations (F ST = 0.019), with evidence of admixture off the southeastern Florida peninsula. Connectivity across larger geographic distances within regions suggests that some larvae are broadly dispersed. Heterozygote deficiencies were detected within the majority of localities suggesting deviation from random mating. Gene flow between ocean regions appears restricted, thus, the most effective management scheme for L. pertusa involves regional reserve networks.

Tropical Atlantic climate response to different freshwater input in high latitudes with an ocean-only general circulation model

NASA Astrophysics Data System (ADS)

Men, Guang; Wan, Xiuquan; Liu, Zedong

2016-10-01

Tropical Atlantic climate change is relevant to the variation of Atlantic meridional overturning circulation (AMOC) through different physical processes. Previous coupled climate model simulation suggested a dipole-like SST structure cooling over the North Atlantic and warming over the South Tropical Atlantic in response to the slowdown of the AMOC. Using an ocean-only global ocean model here, an attempt was made to separate the total influence of various AMOC change scenarios into an oceanic-induced component and an atmospheric-induced component. In contrast with previous freshwater-hosing experiments with coupled climate models, the ocean-only modeling presented here shows a surface warming in the whole tropical Atlantic region and the oceanic-induced processes may play an important role in the SST change in the equatorial south Atlantic. Our result shows that the warming is partly governed by oceanic process through the mechanism of oceanic gateway change, which operates in the regime where freshwater forcing is strong, exceeding 0.3 Sv. Strong AMOC change is required for the gateway mechanism to work in our model because only when the AMOC is sufficiently weak, the North Brazil Undercurrent can flow equatorward, carrying warm and salty north Atlantic subtropical gyre water into the equatorial zone. This threshold is likely to be model-dependent. An improved understanding of these issues may have help with abrupt climate change prediction later.

Using trajectories to explain the moisture budget asymmetry between the Atlantic and Pacific Oceans

NASA Astrophysics Data System (ADS)

Craig, P.; Ferreira, D.; Methven, J.

2017-12-01

The net surface water flux (evaporation minus precipitation minus runoff, E-P-R) of the Atlantic Ocean is approximately 0.4 - 0.6 Sv (1 Sv = 109 kg s-1) larger than that of the Pacific Ocean, as shown in atmospheric and oceanic reanalyses and by oceanographic estimates. This asymmetry is linked to the asymmetry in sea surface salinity and the existence of the Atlantic Meridional Overturning Circulation. It is shown that the reason for the asymmetry in E-P-R is greater precipitation per unit area over the Pacific south of 30N, while evaporation rates are similar over both basins. It is further argued that the Pacific Ocean is anomalous compared to the Atlantic and Indian Oceans in terms of atmospheric moisture flux convergence and precipitation across the tropics and subtropics. To clarify the mechanism by which water vapour is exported out of the Atlantic basin and imported into the Pacific, we use an air mass trajectory model driven by ERA-Interim reanalysis. Using 12-hourly releases of 14-day back trajectories on the boundaries of ocean drainage basins over the period 2010-2014, we are able to partition the atmospheric moisture fluxes between basins according to their origins (i.e. last contact with the boundary layer). We show that at most a quarter of the E-P-R asymmetry is explained by higher moisture export to the Arctic and Southern basins from the Atlantic than from the Pacific. The main contributions come from differences in the longitudinal atmospheric transport of moisture between the Atlantic, Indian and Pacific basins. In particular, during the Asian summer monsoon the recurvature of the low level flow in the Somali Jet results in a much weaker westward moisture transport from the Indian into the Atlantic basin than across Central America (where it is similar to the zonal average) while there is stronger eastward transport from the Indian to Pacific basins. The net effect is stronger moisture convergence into the Pacific, but weaker into the Atlantic

77 FR 50065 - Safety Zone; Jacksonville Sea and Sky Spectacular, Atlantic Ocean; Jacksonville Beach, FL

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-20

... 1625-AA00 Safety Zone; Jacksonville Sea and Sky Spectacular, Atlantic Ocean; Jacksonville Beach, FL... during the Jacksonville Sea and Sky Spectacular air show. The event is scheduled to take place from....T07-0660 Safety Zone; Jacksonville Sea and Sky Spectacular, Atlantic Ocean, Jacksonville Beach, FL. (a...

Mixotrophic basis of Atlantic oligotrophic ecosystems.

PubMed

Hartmann, Manuela; Grob, Carolina; Tarran, Glen A; Martin, Adrian P; Burkill, Peter H; Scanlan, David J; Zubkov, Mikhail V

2012-04-10

Oligotrophic subtropical gyres are the largest oceanic ecosystems, covering >40% of the Earth's surface. Unicellular cyanobacteria and the smallest algae (plastidic protists) dominate CO(2) fixation in these ecosystems, competing for dissolved inorganic nutrients. Here we present direct evidence from the surface mixed layer of the subtropical gyres and adjacent equatorial and temperate regions of the Atlantic Ocean, collected on three Atlantic Meridional Transect cruises on consecutive years, that bacterioplankton are fed on by plastidic and aplastidic protists at comparable rates. Rates of bacterivory were similar in the light and dark. Furthermore, because of their higher abundance, it is the plastidic protists, rather than the aplastidic forms, that control bacterivory in these waters. These findings change our basic understanding of food web function in the open ocean, because plastidic protists should now be considered as the main bacterivores as well as the main CO(2) fixers in the oligotrophic gyres.

78 FR 31840 - Safety Zone; USO Patriotic Festival Air Show, Atlantic Ocean; Virginia Beach, VA

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-28

...-AA00 Safety Zone; USO Patriotic Festival Air Show, Atlantic Ocean; Virginia Beach, VA AGENCY: Coast... provide for the safety of life on navigable waters during the USO Patriotic Festival Air Show. This action... Patriotic Festival Air Show, Atlantic Ocean; Virginia Beach, VA. (a) Regulated Area. The following area is a...

The Ocean-Continent Transition at the North Atlantic Volcanic Margins

NASA Astrophysics Data System (ADS)

White, R. S.; Christie, P. A.; Kusznir, N. J.; Roberts, A. M.; Eccles, J.; Lunnon, Z.; Parkin, C. J.; Smith, L. K.; Spitzer, R.; Roberts, A. W.

2005-05-01

The continental margins of the northern North Atlantic are the best studied volcanic margins in the world. There is a wealth of integrated wide-angle and deep seismic profiles across the continent-ocean transition and the adjacent oceanic and continental crust, several of which form conjugate margin studies. We show new results from the integrated Seismic Imaging and Modelling of Margins (iSIMM) profiles across the Faroes continental margin which image both the extruded volcanics which generate seaward dipping reflector sequences and the underlying lower-crustal intrusions from which the extruded basalts are fed. This enables estimation of the degree of continental stretching and the total volume of melt generated from the mantle at the time of continental breakup. The new results are set in the context of profiles along the entire northern North Atlantic margins. The pattern of melt generation during continental breakup and the initiation of seafloor spreading allows us to map the pattern of enhanced sub-lithospheric mantle temperatures caused by initiation of the Iceland mantle plume over this period. The initial mantle plume thermal anomalies have the shape of rising hot sheets of mantle up to 2000 km in length, which focus into a more axisymmetric shape under the present location of Iceland. These spatial and temporal variations in the mantle temperature exert important controls on the history of uplift and subsidence and thermal maturation of the sediments near the continental margin and its hinterland. The iSIMM Scientific Team comprises NJ Kusznir, RS White, AM Roberts, PAF Christie, R Spitzer, N Hurst, ZC Lunnon, CJ Parkin, AW Roberts, LK Smith, V Tymms, J Eccles and D Healy. The iSIMM project is supported by Liverpool and Cambridge Universities, Schlumberger Cambridge Research, Badley Technology Limited, WesternGeco, Amerada Hess, Anadarko, BP, ConocoPhillips, ENI-UK, Statoil, Shell, the NERC and DTI. We thank WesternGeco for provision of Q-streamer data.

Heat and Freshwater Convergence Anomalies in the Atlantic Ocean Inferred from Observations

NASA Astrophysics Data System (ADS)

Kelly, K. A.; Drushka, K.; Thompson, L.

2015-12-01

Observations of thermosteric and halosteric sea level from hydrographic data, ocean mass from GRACE and altimetric sea surface height are used to infer meridional heat transport (MHT) and freshwater convergence (FWC) anomalies for the Atlantic Ocean. An "unknown control" version of a Kalman filter in each of eight regions extracts smooth estimates of heat transport convergence (HTC) and FWC from discrepancies between the sea level response to monthly surface heat and freshwater fluxes and observed heat and freshwater content. The model is run for 1993-2014. Estimates of MHT anomalies are derived by summing the HTC from north to south and adding a spatially uniform, time-varying MHT derived from updated MHT estimates at 41N (Willis 2010). Estimated anomalies in MHT are comparable to those recently observed at the RAPID/MOCHA line at 26.5N. MHT estimates are relatively insensitive to the choice of heat flux products and are highly coherent spatially. MHT anomalies at 35S resemble estimates of Agulhas Leakage derived from altimeter (LeBars et al 2014) suggesting that the Indian Ocean is the source of the anomalous heat inflow. FWC estimates in the Atlantic Ocean (67N to 35S) resemble estimates of Atlantic river inflow (de Couet and Maurer, GRDC 2009). Increasing values of FWC after 2002 at a time when MHT was decreasing may indicate a feedback between the Atlantic Meridional Overturning Circulation and FWC that would accelerate the AMOC slowdown.

Observed fingerprint of a weakening Atlantic Ocean overturning circulation.

PubMed

Caesar, L; Rahmstorf, S; Robinson, A; Feulner, G; Saba, V

2018-04-01

The Atlantic meridional overturning circulation (AMOC)-a system of ocean currents in the North Atlantic-has a major impact on climate, yet its evolution during the industrial era is poorly known owing to a lack of direct current measurements. Here we provide evidence for a weakening of the AMOC by about 3 ± 1 sverdrups (around 15 per cent) since the mid-twentieth century. This weakening is revealed by a characteristic spatial and seasonal sea-surface temperature 'fingerprint'-consisting of a pattern of cooling in the subpolar Atlantic Ocean and warming in the Gulf Stream region-and is calibrated through an ensemble of model simulations from the CMIP5 project. We find this fingerprint both in a high-resolution climate model in response to increasing atmospheric carbon dioxide concentrations, and in the temperature trends observed since the late nineteenth century. The pattern can be explained by a slowdown in the AMOC and reduced northward heat transport, as well as an associated northward shift of the Gulf Stream. Comparisons with recent direct measurements from the RAPID project and several other studies provide a consistent depiction of record-low AMOC values in recent years.

A new collective view of oceanography of the Arctic and North Atlantic basins

NASA Astrophysics Data System (ADS)

Yashayaev, Igor; Seidov, Dan; Demirov, Entcho

2015-03-01

We review some historical aspects of the major observational programs in the North Atlantic and adjacent regions that contributed to establishing and maintaining the global ocean climate monitoring network. The paper also presents the oceanic perspectives of climate change and touches the important issues of ocean climate variability on time scales from years to decades. Some elements of the improved understanding of the causes and mechanisms of variability in the subpolar North Atlantic and adjacent seas are discussed in detail. The sophistication of current oceanographic analysis, especially in connection with the most recent technological breakthroughs - notably the launch of the global array of profiling Argo floats - allows us to approach new challenges in ocean research. We demonstrate how the ocean-climate changes in the subpolar basins and polar seas correlate with variations in the major climate indices such as the North Atlantic Oscillation and Atlantic Multidecadal Oscillation, and discuss possible connections between the unprecedented changes in the Arctic and Greenland ice-melt rates observed over the past decade and variability of hydrographic conditions in the Labrador Sea. Furthermore, a synthesis of shipboard and Argo measurements in the Labrador Sea reveals the effects of the regional climate trends such as freshening of the upper layer - possible causes of which are also discussed - on the winter convection in the Labrador Sea including its strength, duration and spatial extent. These changes could have a profound impact on the regional and planetary climates. A section with the highlights of all papers comprising the Special Issue concludes the Preface.

33 CFR 334.525 - Atlantic Ocean off John F. Kennedy Space Center, FL; restricted area.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Atlantic Ocean off John F. Kennedy Space Center, FL; restricted area. 334.525 Section 334.525 Navigation and Navigable Waters CORPS... REGULATIONS § 334.525 Atlantic Ocean off John F. Kennedy Space Center, FL; restricted area. (a) The area. The...

33 CFR 334.525 - Atlantic Ocean off John F. Kennedy Space Center, FL; restricted area.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Atlantic Ocean off John F. Kennedy Space Center, FL; restricted area. 334.525 Section 334.525 Navigation and Navigable Waters CORPS... REGULATIONS § 334.525 Atlantic Ocean off John F. Kennedy Space Center, FL; restricted area. (a) The area. The...

33 CFR 334.525 - Atlantic Ocean off John F. Kennedy Space Center, FL; restricted area.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Atlantic Ocean off John F. Kennedy Space Center, FL; restricted area. 334.525 Section 334.525 Navigation and Navigable Waters CORPS... REGULATIONS § 334.525 Atlantic Ocean off John F. Kennedy Space Center, FL; restricted area. (a) The area. The...

33 CFR 334.525 - Atlantic Ocean off John F. Kennedy Space Center, FL; restricted area.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Atlantic Ocean off John F. Kennedy Space Center, FL; restricted area. 334.525 Section 334.525 Navigation and Navigable Waters CORPS... REGULATIONS § 334.525 Atlantic Ocean off John F. Kennedy Space Center, FL; restricted area. (a) The area. The...

33 CFR 334.525 - Atlantic Ocean off John F. Kennedy Space Center, FL; restricted area.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false Atlantic Ocean off John F. Kennedy Space Center, FL; restricted area. 334.525 Section 334.525 Navigation and Navigable Waters CORPS... REGULATIONS § 334.525 Atlantic Ocean off John F. Kennedy Space Center, FL; restricted area. (a) The area. The...

33 CFR 165.T01-0542 - Safety Zones: Neptune Deepwater Port, Atlantic Ocean, Boston, MA.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Safety Zones: Neptune Deepwater Port, Atlantic Ocean, Boston, MA. 165.T01-0542 Section 165.T01-0542 Navigation and Navigable Waters... Guard District § 165.T01-0542 Safety Zones: Neptune Deepwater Port, Atlantic Ocean, Boston, MA. (a...

77 FR 50062 - Safety Zone; Embry-Riddle Wings and Waves, Atlantic Ocean; Daytona Beach, FL

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-20

... 1625-AA00 Safety Zone; Embry-Riddle Wings and Waves, Atlantic Ocean; Daytona Beach, FL AGENCY: Coast...-Riddle Wings and Waves air show. The event is scheduled to take place from Thursday, October 11, 2012...: Sec. 165.T07-0653 Safety Zone; Embry Riddle Wings and Waves, Atlantic Ocean, Daytona Beach, FL. (a...

Large-Scale Distribution and Activity of Prokaryotes in Deep-Sea Surface Sediments of the Mediterranean Sea and the Adjacent Atlantic Ocean

PubMed Central

Giovannelli, Donato; Molari, Massimiliano; d’Errico, Giuseppe; Baldrighi, Elisa; Pala, Claudia; Manini, Elena

2013-01-01

The deep-sea represents a substantial portion of the biosphere and has a major influence on carbon cycling and global biogeochemistry. Benthic deep-sea prokaryotes have crucial roles in this ecosystem, with their recycling of organic matter from the photic zone. Despite this, little is known about the large-scale distribution of prokaryotes in the surface deep-sea sediments. To assess the influence of environmental and trophic variables on the large-scale distribution of prokaryotes, we investigated the prokaryotic assemblage composition (Bacteria to Archaea and Euryarchaeota to Crenarchaeota ratio) and activity in the surface deep-sea sediments of the Mediterranean Sea and the adjacent North Atlantic Ocean. Prokaryotic abundance and biomass did not vary significantly across the Mediterranean Sea; however, there were depth-related trends in all areas. The abundance of prokaryotes was positively correlated with the sedimentary concentration of protein, an indicator of the quality and bioavailability of organic matter. Moving eastwards, the Bacteria contribution to the total prokaryotes decreased, which appears to be linked to the more oligotrophic conditions of the Eastern Mediterranean basins. Despite the increased importance of Archaea, the contributions of Crenarchaeota Marine Group I to the total pool was relatively constant across the investigated stations, with the exception of Matapan-Vavilov Deep, in which Euryarchaeota Marine Group II dominated. Overall, our data suggest that deeper areas of the Mediterranean Sea share more similar communities with each other than with shallower sites. Freshness and quality of sedimentary organic matter were identified through Generalized Additive Model analysis as the major factors for describing the variation in the prokaryotic community structure and activity in the surface deep-sea sediments. Longitude was also important in explaining the observed variability, which suggests that the overlying water masses might have a

Advection of sulfur dioxide over the western Atlantic Ocean during CITE 3

NASA Technical Reports Server (NTRS)

Thornton, D. C.; Bandy, A. R.; Beltz, N.; Driedger, A. R., III; Ferek, R.

1993-01-01

During the NASA Chemical Instrumentation Test and Evaluation 3 sulfur intercomparison over the western Atlantic Ocean, five techniques for the determination of sulfur dioxide were evaluated. The response times of the techniques varied from 3 to 30 min. Based on the ensemble of measurements reported, it was clear that advection of SO2 from the North American continent occurred in the boundary layer (altitude less than 1 km) with only one exception. The vertical distribution of SO2 above the boundary layer for the northern and southern Atlantic Ocean was remarkably similar duing this experiment.

The Subpolar North Atlantic Ocean Heat Content Variability and its Decomposition.

PubMed

Zhang, Weiwei; Yan, Xiao-Hai

2017-10-23

The Subpolar North Atlantic (SPNA) is one of the most important areas to global climate because its ocean heat content (OHC) is highly correlated with the Atlantic Meridional Overturning Circulation (AMOC), and its circulation strength affects the salt transport by the AMOC, which in turn feeds and sustains the strength of the AMOC. Moreover, the recent global surface warming "hiatus" may be attributed to the SPNA as one of the major planetary heat sinks. Although almost synchronized before 1996, the OHC has greater spatial disparities afterwards, which cannot be explained as driven by the North Atlantic Oscillation (NAO). Temperature decomposition reveals that the western SPNA OHC is mainly determined by the along isopycnal changes, while in the eastern SPNA along isopycnal changes and isopycnal undulation are both important. Further analysis indicates that heat flux dominates the western SPNA OHC, but in the eastern SPNA wind forcing affects the OHC significantly. It is worth noting that the along isopycnal OHC changes can also induce heaving, thus the observed heaving domination in global oceans cannot mask the extra heat in the ocean during the recent "hiatus".

Upper Ocean Circulation in the Glacial Northeast Atlantic during Heinrich Stadials Ice-Sheet Retreat

NASA Astrophysics Data System (ADS)

Toucanne, S.; Soulet, G.; Bosq, M.; Marjolaine, S.; Zaragosi, S.; Bourillet, J. F.; Bayon, G.

2016-12-01

Intermediate ocean water variability is involved in climate changes over geological timescales. As a prominent example, changes in North Atlantic subsurface water properties (including warming) during Heinrich Stadials may have triggered the so-called Heinrich events through ice-shelf loss and attendant ice-stream acceleration. While the origin of Heinrich Stadials and subsequent iceberg calving remains controversial, paleoceanographic research efforts mainly focus on the deep Atlantic overturning, leaving the upper ocean largely unexplored. To further evaluate variability in upper ocean circulation and its possible relationship with ice-sheet instabilities, a depth-transect of eight cores (BOBGEO and GITAN-TANDEM cruises) from the Northeast Atlantic (down to 2 km water depth) have been used to investigate kinematic and chemical changes in the upper ocean during the last glacial period. Our results reveal that near-bottom flow speeds (reconstructed by using sortable silt mean grain-size and X-ray fluorescence core-scanner Zr/Rb ratio) and water-masses chemistry (carbon and neodymium isotopes performed on foraminifera) substantially changed in phase with the millennial-scale climate changes recognized in the ice-core records. Our results are compared with paleoceanographic reconstructions of the 'Western Boundary Undercurrent' in order to discuss regional hydrographic differences at both sides of the North Atlantic, as well as with the fluctuations of both the marine- (through ice-rafted debris) and terrestrial-terminating ice-streams (through meltwater discharges) of the circum-Atlantic ice-sheets. Particular attention will be given to the Heinrich Stadials and concomitant Channel River meltwater discharges into the Northeast Atlantic in response to the melting of the European Ice-Sheet. This comparison helps to disentangle the cryosphere-ocean interactions throughout the last ice age, and the sequence of events occurring in the course of the Heinrich Stadials.

Evolutionary Diversification of Banded Tube-Dwelling Anemones (Cnidaria; Ceriantharia; Isarachnanthus) in the Atlantic Ocean

PubMed Central

Stampar, Sergio N.; Maronna, Maximiliano M.; Vermeij, Mark J. A.; Silveira, Fabio L. d.; Morandini, André C.

2012-01-01

The use of molecular data for species delimitation in Anthozoa is still a very delicate issue. This is probably due to the low genetic variation found among the molecular markers (primarily mitochondrial) commonly used for Anthozoa. Ceriantharia is an anthozoan group that has not been tested for genetic divergence at the species level. Recently, all three Atlantic species described for the genus Isarachnanthus of Atlantic Ocean, were deemed synonyms based on morphological simmilarities of only one species: Isarachnanthus maderensis. Here, we aimed to verify whether genetic relationships (using COI, 16S, ITS1 and ITS2 molecular markers) confirmed morphological affinities among members of Isarachnanthus from different regions across the Atlantic Ocean. Results from four DNA markers were completely congruent and revealed that two different species exist in the Atlantic Ocean. The low identification success and substantial overlap between intra and interspecific COI distances render the Anthozoa unsuitable for DNA barcoding, which is not true for Ceriantharia. In addition, genetic divergence within and between Ceriantharia species is more similar to that found in Medusozoa (Hydrozoa and Scyphozoa) than Anthozoa and Porifera that have divergence rates similar to typical metazoans. The two genetic species could also be separated based on micromorphological characteristics of their cnidomes. Using a specimen of Isarachnanthus bandanensis from Pacific Ocean as an outgroup, it was possible to estimate the minimum date of divergence between the clades. The cladogenesis event that formed the species of the Atlantic Ocean is estimated to have occured around 8.5 million years ago (Miocene) and several possible speciation scenarios are discussed. PMID:22815928

Evolutionary diversification of banded tube-dwelling anemones (Cnidaria; Ceriantharia; Isarachnanthus) in the Atlantic Ocean.

PubMed

Stampar, Sergio N; Maronna, Maximiliano M; Vermeij, Mark J A; Silveira, Fabio L d; Morandini, André C

2012-01-01

The use of molecular data for species delimitation in Anthozoa is still a very delicate issue. This is probably due to the low genetic variation found among the molecular markers (primarily mitochondrial) commonly used for Anthozoa. Ceriantharia is an anthozoan group that has not been tested for genetic divergence at the species level. Recently, all three Atlantic species described for the genus Isarachnanthus of Atlantic Ocean, were deemed synonyms based on morphological simmilarities of only one species: Isarachnanthus maderensis. Here, we aimed to verify whether genetic relationships (using COI, 16S, ITS1 and ITS2 molecular markers) confirmed morphological affinities among members of Isarachnanthus from different regions across the Atlantic Ocean. Results from four DNA markers were completely congruent and revealed that two different species exist in the Atlantic Ocean. The low identification success and substantial overlap between intra and interspecific COI distances render the Anthozoa unsuitable for DNA barcoding, which is not true for Ceriantharia. In addition, genetic divergence within and between Ceriantharia species is more similar to that found in Medusozoa (Hydrozoa and Scyphozoa) than Anthozoa and Porifera that have divergence rates similar to typical metazoans. The two genetic species could also be separated based on micromorphological characteristics of their cnidomes. Using a specimen of Isarachnanthus bandanensis from Pacific Ocean as an outgroup, it was possible to estimate the minimum date of divergence between the clades. The cladogenesis event that formed the species of the Atlantic Ocean is estimated to have occured around 8.5 million years ago (Miocene) and several possible speciation scenarios are discussed.

Strontium-90: concentrations in surface waters of the Atlantic Ocean.

PubMed

Bowen, V T; Noshkin, V E; Volchok, H L; Sugihara, T T

1969-05-16

From the large body of analyses of strontium-90 in surface waters of the Atlantic Ocean, annual average concentrations (from 10 degrees N to 70 degrees N) have been compared to those predicted. The data indicate higher fall-out over ocean than over land and confirm the rapid rates of down-mixing shown by most studies of subsurface strontium-90.

Modelling size-fractionated primary production in the Atlantic Ocean from remote sensing

NASA Astrophysics Data System (ADS)

Brewin, Robert J. W.; Tilstone, Gavin H.; Jackson, Thomas; Cain, Terry; Miller, Peter I.; Lange, Priscila K.; Misra, Ankita; Airs, Ruth L.

2017-11-01

Marine primary production influences the transfer of carbon dioxide between the ocean and atmosphere, and the availability of energy for the pelagic food web. Both the rate and the fate of organic carbon from primary production are dependent on phytoplankton size. A key aim of the Atlantic Meridional Transect (AMT) programme has been to quantify biological carbon cycling in the Atlantic Ocean and measurements of total primary production have been routinely made on AMT cruises, as well as additional measurements of size-fractionated primary production on some cruises. Measurements of total primary production collected on the AMT have been used to evaluate remote-sensing techniques capable of producing basin-scale estimates of primary production. Though models exist to estimate size-fractionated primary production from satellite data, these have not been well validated in the Atlantic Ocean, and have been parameterised using measurements of phytoplankton pigments rather than direct measurements of phytoplankton size structure. Here, we re-tune a remote-sensing primary production model to estimate production in three size fractions of phytoplankton (<2 μm, 2-10 μm and >10 μm) in the Atlantic Ocean, using measurements of size-fractionated chlorophyll and size-fractionated photosynthesis-irradiance experiments conducted on AMT 22 and 23 using sequential filtration-based methods. The performance of the remote-sensing technique was evaluated using: (i) independent estimates of size-fractionated primary production collected on a number of AMT cruises using 14C on-deck incubation experiments and (ii) Monte Carlo simulations. Considering uncertainty in the satellite inputs and model parameters, we estimate an average model error of between 0.27 and 0.63 for log10-transformed size-fractionated production, with lower errors for the small size class (<2 μm), higher errors for the larger size classes (2-10 μm and >10 μm), and errors generally higher in oligotrophic waters

Atlantic meridional heat transports computed from balancing Earth's energy locally: AMOC and Ocean Meridional Heat Transport

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trenberth, Kevin E.; Fasullo, John T.

The Atlantic Meridional Overturning Circulation plays a major role in moving heat and carbon around in the ocean. A new estimate of ocean heat transports for 2000 through 2013 throughout the Atlantic is derived. Top-of-atmosphere radiation is combined with atmospheric reanalyses to estimate surface heat fluxes and combined with vertically integrated ocean heat content to estimate ocean heat transport divergence as a residual. Atlantic peak northward ocean heat transports average 1.18 ± 0.13PW (1 sigma) at 15°N but vary considerably in latitude and time. Results agree well with observational estimates at 26.5°N from the RAPID array, but for 2004–2013 themore » meridional heat transport is 1.00 ± 0.11PW versus 1.23 ± 0.11PW for RAPID. In addition, these results have no hint of a trend, unlike the RAPID results. Finally, strong westerlies north of a meridian drive ocean currents and an ocean heat loss into the atmosphere that is exacerbated by a decrease in ocean heat transport northward.« less

Atlantic meridional heat transports computed from balancing Earth's energy locally: AMOC and Ocean Meridional Heat Transport

DOE PAGES

Trenberth, Kevin E.; Fasullo, John T.

2017-02-18

The Atlantic Meridional Overturning Circulation plays a major role in moving heat and carbon around in the ocean. A new estimate of ocean heat transports for 2000 through 2013 throughout the Atlantic is derived. Top-of-atmosphere radiation is combined with atmospheric reanalyses to estimate surface heat fluxes and combined with vertically integrated ocean heat content to estimate ocean heat transport divergence as a residual. Atlantic peak northward ocean heat transports average 1.18 ± 0.13PW (1 sigma) at 15°N but vary considerably in latitude and time. Results agree well with observational estimates at 26.5°N from the RAPID array, but for 2004–2013 themore » meridional heat transport is 1.00 ± 0.11PW versus 1.23 ± 0.11PW for RAPID. In addition, these results have no hint of a trend, unlike the RAPID results. Finally, strong westerlies north of a meridian drive ocean currents and an ocean heat loss into the atmosphere that is exacerbated by a decrease in ocean heat transport northward.« less

Meiofauna assemblages of the Condor Seamount (North-East Atlantic Ocean) and adjacent deep-sea sediments

NASA Astrophysics Data System (ADS)

Zeppilli, Daniela; Bongiorni, Lucia; Cattaneo, Antonio; Danovaro, Roberto; Santos, Ricardo Serrão

2013-12-01

Seamounts are currently considered hotspots of biodiversity and biomass for macro- and megabenthic taxa, but knowledge of meiofauna is still limited. Studies have revealed the existence of highly diverse meiofauna assemblages; however most data are mainly qualitative or focused only on specific groups, thus preventing comparisons among seamounts and with other deep-sea areas. This study, conducted on Condor Seamount (Azores, North-East Atlantic Ocean), describes variation in abundance, biomass, community structure and biodiversity of benthic meiofauna from five sites located on the Condor Seamount: and one site away from the seamount. While the summit of the seamount hosted the highest alpha biodiversity, the flanks and the bases showed a rich meiofauna assemblage in terms of abundance and biomass. The observed marked differences in grain size composition of sediments reflected the oceanographic conditions impacting different sectors of the Condor seamount, and could play an important role in the spatial distribution of different meiofaunal taxa. Trophic conditions (biochemical composition of organic matter) explained 78% of the variability in the meiofauna biomass pattern while sediment grain influenced the vertical distribution of meiofauna and only partially explained meiofaunal taxa composition. This study provides a further advancement in the knowledge of meiofaunal communities of seamounts. Only a deeper understanding of the whole benthic communities (including meiofauna) will allow to elaborate effective management and conservation tools for seamount ecosystems.

Arctic Contribution to Upper-Ocean Variability in the North Atlantic.

NASA Astrophysics Data System (ADS)

Walsh, John E.; Chapman, William L.

1990-12-01

Because much of the deep water of the world's oceans forms in the high-latitude North Atlantic, the potential climatic leverage of salinity and temperature anomalies in this region is large. Substantial variations of sea ice have accompanied North Atlantic salinity and temperature anomalies, especially the extreme and long-lived `Great Salinity Anomaly' of the late 1960s and early 1970s. Atmospheric pressure data are used hem to show that the local forcing of high-latitude North Atlantic Ocean fluctuations is augmented by antecedent atmospheric circulation anomalies over the central Arctic. These circulation anomalies are consistent with enhanced wind-forcing of thicker, older ice into the Transpolar Drift Stream and an enhanced export of sea ice (fresh water) from the Arctic into the Greenland Sea prior to major episodes of ice severity in the Greenland and Iceland seas. An index of the pressure difference between southern Greenland and the Arctic-Asian coast reached its highest value of the twentieth century during the middle-to-late 1960s, the approximate time of the earliest observation documentation of the Great Salinity Anomaly.

Large Tabular Iceberg, South Atlantic Ocean

NASA Image and Video Library

1991-09-18

This large tabular iceberg, broken off from the Antarctic Ice Sheet, was spotted in the South Atlantic Ocean (57.0S, 57.0W) southeast of the tip of South America as it was slowly being moved north and east by wind, current and tidal influences. This type of iceberg, never to be seen in the northern hemisphere, is typical for Antarctica. Although some such icebergs are as large as 100 km in length, this one measures about 35 by 69 km.

Large Tabular Iceberg, South Atlantic Ocean

NASA Technical Reports Server (NTRS)

1991-01-01

This large tabular iceberg, broken off from the Antarctic Ice Sheet, was spotted in the South Atlantic Ocean (57.0S, 57.0W) southeast of the tip of South America as it was slowly being moved north and east by wind, current and tidal influences. This type of iceberg, never to be seen in the northern hemisphere, is typical for Antarctica. Although some such icebergs are as large as 100 km in length, this one measures about 35 by 69 km.

Break-up of the Atlantic deep western boundary current into eddies at 8 degrees S.

PubMed

Dengler, M; Schott, F A; Eden, C; Brandt, P; Fischer, J; Zantopp, R J

2004-12-23

The existence in the ocean of deep western boundary currents, which connect the high-latitude regions where deep water is formed with upwelling regions as part of the global ocean circulation, was postulated more than 40 years ago. These ocean currents have been found adjacent to the continental slopes of all ocean basins, and have core depths between 1,500 and 4,000 m. In the Atlantic Ocean, the deep western boundary current is estimated to carry (10-40) x 10(6) m3 s(-1) of water, transporting North Atlantic Deep Water--from the overflow regions between Greenland and Scotland and from the Labrador Sea--into the South Atlantic and the Antarctic circumpolar current. Here we present direct velocity and water mass observations obtained in the period 2000 to 2003, as well as results from a numerical ocean circulation model, showing that the Atlantic deep western boundary current breaks up at 8 degrees S. Southward of this latitude, the transport of North Atlantic Deep Water into the South Atlantic Ocean is accomplished by migrating eddies, rather than by a continuous flow. Our model simulation indicates that the deep western boundary current breaks up into eddies at the present intensity of meridional overturning circulation. For weaker overturning, continuation as a stable, laminar boundary flow seems possible.

A new multi-proxy reconstruction of Atlantic deep ocean circulation during the warm mid-Pliocene

NASA Astrophysics Data System (ADS)

Riesselman, C. R.; Dowsett, H. J.; Scher, H. D.; Robinson, M. M.

2011-12-01

The mid-Pliocene (3.264 - 3.025 Ma) is the most recent interval in Earth's history with sustained global temperatures in the range of warming predicted for the 21st century, providing an appealing analog with which to examine the Earth system changes we might encounter in the coming century. Ongoing sea surface and deep ocean temperature reconstructions and coupled ocean-atmosphere general circulation model simulations by the USGS PRISM (Pliocene Research Interpretation and Synoptic Mapping) Group identify a dramatic North Atlantic warm anomaly coupled with increased evaporation in the mid-Pliocene, possibly driving enhanced meridional overturning circulation and North Atlantic Deep Water production. However deep ocean temperature is not a conclusive proxy for water mass, and most coupled model simulations predict transient decreases in North Atlantic Deep Water production in 21st century, presenting a contrasting picture of future warmer worlds. Here, we present early results from a new multi-proxy reconstruction of Atlantic deep ocean circulation during the warm mid-Pliocene, using δ13C of benthic foraminifera as a proxy for water mass age and the neodymium isotopic imprint on fossil fish teeth as a proxy for water mass source region along a three-site depth transect from the Walvis Ridge (subtropical South Atlantic). The deep ocean circulation reconstructions resulting from this project will add a new dimension to the PRISM effort and will be useful for both initialization and evaluation of future model simulations.

A numerical study of the plume in Cape Fear River Estuary and adjacent coastal ocean

NASA Astrophysics Data System (ADS)

Xia, M.; Xia, L.; Pietrafesa, L. J.

2006-12-01

Cape Fear River Estuary (CFRE), located in southeast North Carolina, is the only river estuary system in the state which is directly connected to the Atlantic Ocean. It is also an important nursery for economically and ecologically important juvenile fish, crabs, shrimp, and other species because of the tidal influence and saline waters. In this study, Environmental Fluid Dynamic Code (EFDC) is used to simulate the salinity plume and trajectory distribution at the mouth of the CFRE and adjacent coastal ocean. Prescribed with the climatological freshwater discharge rates in the rivers, the modeling system was used to simulate the salinity plume and trajectory distribution distribution in the mouth of the CFRE under the influence of climatological wind conditions and tidal effect. We analyzed the plume formation processes and the strong relationship between the various plume distributions with respect to the wind and river discharge in the region. The simulations also indicate that strong winds tend to reduce the surface CFRE plume size and distorting the bulge region near the estuary mouth due to enhanced wind induced surface mixing. Even moderate wind speeds could fully reverse the buoyancy-driven plume structure in CFRE under normal river discharge conditions. Tide and the river discharge also are important factors to influence the plume structure. The comparions between the distribution of salinity plume and trajectory also are discussed in the study.

Basin-scale observations of isoprene and monoterpenes in the Arctic and Atlantic Oceans

NASA Astrophysics Data System (ADS)

Carpenter, L.; Hackenberg, S.; Andrews, S.; Minaeian, J.; Chance, R.; Arnold, S.; Spracklen, D. V.; Walker, H.; Brewin, R. J.; Tarran, G.; Tilstone, G.; Small, A.; Bouman, H. A.

2016-12-01

We report surface ocean concentrations, atmospheric mixing ratios and calculated sea-to-air fluxes of isoprene and six monoterpenes (α- and β-pinene, myrcene, Δ 3-carene, ocimene, and limonene) spanning approximately 130 degrees of latitude (80 °N- 50 °S) in the Arctic and Atlantic Oceans. Oceanic isoprene concentrations showed covariance with a number of concurrently monitored biological parameters, and these relationships were dependent on sea surface temperatures. Parameterisations of isoprene seawater concentrations based on linear regression analyses of these relationships perform well for Arctic and Atlantic data. Levels of all monoterpenes were generally low, with oceanic concentrations ranging from below the detection limit of <1 pmol L-1 to 5 pmol L-1 . In air, monoterpene mixing ratios varied from below the detection limit ( 1 pptv) to 5 pptv, after careful filtering for ship-related contamination. Unlike in previous studies, no clear trends or relationships of the monoterpenes with biological data were found. Limonene showed generally the highest levels in water (up to 84 pmol L-1 in the Atlantic Ocean) and air; however this was attributed mostly to shipborne contamination. We calculate global sea-air fluxes of isoprene and monoterpenes based on this data and compare to previous estimates.

Atmospheric deposition of methanol over the Atlantic Ocean

PubMed Central

Yang, Mingxi; Nightingale, Philip D.; Beale, Rachael; Liss, Peter S.; Blomquist, Byron; Fairall, Christopher

2013-01-01

In the troposphere, methanol (CH3OH) is present ubiquitously and second in abundance among organic gases after methane. In the surface ocean, methanol represents a supply of energy and carbon for marine microbes. Here we report direct measurements of air–sea methanol transfer along a ∼10,000-km north–south transect of the Atlantic. The flux of methanol was consistently from the atmosphere to the ocean. Constrained by the aerodynamic limit and measured rate of air–sea sensible heat exchange, methanol transfer resembles a one-way depositional process, which suggests dissolved methanol concentrations near the water surface that are lower than what were measured at ∼5 m depth, for reasons currently unknown. We estimate the global oceanic uptake of methanol and examine the lifetimes of this compound in the lower atmosphere and upper ocean with respect to gas exchange. We also constrain the molecular diffusional resistance above the ocean surface—an important term for improving air–sea gas exchange models. PMID:24277830

Atmospheric deposition of methanol over the Atlantic Ocean.

PubMed

Yang, Mingxi; Nightingale, Philip D; Beale, Rachael; Liss, Peter S; Blomquist, Byron; Fairall, Christopher

2013-12-10

In the troposphere, methanol (CH3OH) is present ubiquitously and second in abundance among organic gases after methane. In the surface ocean, methanol represents a supply of energy and carbon for marine microbes. Here we report direct measurements of air-sea methanol transfer along a ∼10,000-km north-south transect of the Atlantic. The flux of methanol was consistently from the atmosphere to the ocean. Constrained by the aerodynamic limit and measured rate of air-sea sensible heat exchange, methanol transfer resembles a one-way depositional process, which suggests dissolved methanol concentrations near the water surface that are lower than what were measured at ∼5 m depth, for reasons currently unknown. We estimate the global oceanic uptake of methanol and examine the lifetimes of this compound in the lower atmosphere and upper ocean with respect to gas exchange. We also constrain the molecular diffusional resistance above the ocean surface-an important term for improving air-sea gas exchange models.

Persistent organic pollutants in the Atlantic and southern oceans and oceanic atmosphere.

PubMed

Luek, Jenna L; Dickhut, Rebecca M; Cochran, Michele A; Falconer, Renee L; Kylin, Henrik

2017-04-01

Persistent organic pollutants (POPs) continue to cycle through the atmosphere and hydrosphere despite banned or severely restricted usages. Global scale analyses of POPs are challenging, but knowledge of the current distribution of these compounds is needed to understand the movement and long-term consequences of their global use. In the current study, air and seawater samples were collected Oct. 2007-Jan. 2008 aboard the Icebreaker Oden en route from Göteborg, Sweden to McMurdo Station, Antarctica. Both air and surface seawater samples consistently contained α-hexachlorocyclohexane (α-HCH), γ-HCH, hexachlorobenzene (HCB), α-Endosulfan, and polychlorinated biphenyls (PCBs). Sample concentrations for most POPs in air were higher in the northern hemisphere with the exception of HCB, which had high gas phase concentrations in the northern and southern latitudes and low concentrations near the equator. South Atlantic and Southern Ocean seawater had a high ratio of α-HCH to γ-HCH, indicating persisting levels from technical grade sources. The Atlantic and Southern Ocean continue to be net sinks for atmospheric α-, γ-HCH, and Endosulfan despite declining usage. Copyright © 2017 Elsevier B.V. All rights reserved.

Barium isotopes reveal role of ocean circulation on barium cycling in the Atlantic

NASA Astrophysics Data System (ADS)

Bates, Stephanie L.; Hendry, Katharine R.; Pryer, Helena V.; Kinsley, Christopher W.; Pyle, Kimberley M.; Woodward, E. Malcolm S.; Horner, Tristan J.

2017-05-01

We diagnose the relative influences of local-scale biogeochemical cycling and regional-scale ocean circulation on Atlantic barium cycling by analysing four new depth profiles of dissolved Ba concentrations and isotope compositions from the South and tropical North Atlantic. These new profiles exhibit systematic vertical, zonal and meridional variations that reflect the influence of both local-scale barite cycling and large-scale ocean circulation. Epipelagic decoupling of dissolved Ba and Si reported previously in the tropics is also found to be associated with significant Ba isotope heterogeneity. As such, we contend that this decoupling originates from the depth segregation of opal and barite formation but is exacerbated by weak vertical mixing. Zonal influence from isotopically-'heavy' water masses in the western North Atlantic evidence the advective inflow of Ba-depleted Upper Labrador Sea Water, which is not seen in the eastern basin or the South Atlantic. Meridional variations in Atlantic Ba isotope systematics below 2000 m appear entirely controlled by conservative mixing. Using an inverse isotopic mixing model, we calculate the Ba isotope composition of the Ba-poor northern end-member as +0.45 ‰ and the Ba-rich southern end-member +0.26 ‰, relative to NIST SRM 3104a. The near-conservative behaviour of Ba below 2000 m indicates that Ba isotopes can serve as an independent tracer of the provenance of northern- versus southern-sourced water masses in the deep Atlantic Ocean. This finding may prove useful in palaeoceanographic studies, should appropriate sedimentary archives be identified, and offers new insights into the processes that cycle Ba in seawater.

Oceanic Situational Awareness over the North Atlantic Corridor

NASA Technical Reports Server (NTRS)

Welch, Bryan; Greenfield, Israel

2005-01-01

Air traffic control (ATC) mandated, aircraft separations over the oceans impose a limitation on traffic capacity for a given corridor, given the projected traffic growth over the oceanic domain. The separations result from a lack of acceptable situational awareness over oceans where radar position updates are not available. This study considers the use of Automatic Dependent Surveillance (ADS) data transmitted over a commercial satellite communications system as an approach to provide ATC with the needed situational awareness and thusly allow for reduced aircraft separations. This study uses Federal Aviation Administration data from a single day for the North Atlantic Corridor to analyze traffic loading to be used as a benchmark against which to compare several approaches for coordinating data transmissions from the aircraft to the satellites.

Interhemispheric Changes in Atlantic Ocean Heat Content and Their Link to Global Monsoons

NASA Astrophysics Data System (ADS)

Lopez, H.; Lee, S. K.; Dong, S.; Goni, G. J.

2015-12-01

This study tested the hypothesis whether low frequency decadal variability of the South Atlantic meridional heat transport (SAMHT) influences decadal variability of the global monsoons. A multi-century run from a state-of-the-art coupled general circulation model is used as basis for the analysis. Our findings indicate that multi-decadal variability of the South Atlantic Ocean plays a key role in modulating atmospheric circulation via interhemispheric changes in Atlantic Ocean heat content. Weaker SAMHT produces anomalous ocean heat divergence over the South Atlantic resulting in negative ocean heat content anomaly about 15 years later. This, in turn, forces a thermally direct anomalous interhemispheric Hadley circulation in the atmosphere, transporting heat from the northern hemisphere (NH) to the southern hemisphere (SH) and moisture from the SH to the NH, thereby intensify (weaken) summer (winter) monsoon in the NH and winter (summer) monsoon in the SH. Results also show that anomalous atmospheric eddies, both transient and stationary, transport heat northward in both hemispheres producing eddy heat flux convergence (divergence) in the NH (SH) around 15-30°, reinforcing the anomalous Hadley circulation. The effect of eddies on the NH (SH) poleward of 30° is opposite with heat flux divergence (convergence), which must be balanced by sinking (rising) motion, consistent with a poleward (equatorward) displacement of the jet stream and mean storm track. The mechanism described here could easily be interpreted for the case of strong SAMHT, with the reverse influence on the interhemispheric atmospheric circulation and monsoons. Overall, SAMHT decadal variability leads its atmospheric response by about 15 years, suggesting that the South Atlantic is a potential predictor of global climate variability.

Latitudinal variation in virus-induced mortality of phytoplankton across the North Atlantic Ocean

PubMed Central

Mojica, Kristina D A; Huisman, Jef; Wilhelm, Steven W; Brussaard, Corina P D

2016-01-01

Viral lysis of phytoplankton constrains marine primary production, food web dynamics and biogeochemical cycles in the ocean. Yet, little is known about the biogeographical distribution of viral lysis rates across the global ocean. To address this, we investigated phytoplankton group-specific viral lysis rates along a latitudinal gradient within the North Atlantic Ocean. The data show large-scale distribution patterns of different virus groups across the North Atlantic that are associated with the biogeographical distributions of their potential microbial hosts. Average virus-mediated lysis rates of the picocyanobacteria Prochlorococcus and Synechococcus were lower than those of the picoeukaryotic and nanoeukaryotic phytoplankton (that is, 0.14 per day compared with 0.19 and 0.23 per day, respectively). Total phytoplankton mortality (virus plus grazer-mediated) was comparable to the gross growth rate, demonstrating high turnover rates of phytoplankton populations. Virus-induced mortality was an important loss process at low and mid latitudes, whereas phytoplankton mortality was dominated by microzooplankton grazing at higher latitudes (>56°N). This shift from a viral-lysis-dominated to a grazing-dominated phytoplankton community was associated with a decrease in temperature and salinity, and the decrease in viral lysis rates was also associated with increased vertical mixing at higher latitudes. Ocean-climate models predict that surface warming will lead to an expansion of the stratified and oligotrophic regions of the world's oceans. Our findings suggest that these future shifts in the regional climate of the ocean surface layer are likely to increase the contribution of viral lysis to phytoplankton mortality in the higher-latitude waters of the North Atlantic, which may potentially reduce transfer of matter and energy up the food chain and thus affect the capacity of the northern North Atlantic to act as a long-term sink for CO2. PMID:26262815

Latitudinal variation in virus-induced mortality of phytoplankton across the North Atlantic Ocean.

PubMed

Mojica, Kristina D A; Huisman, Jef; Wilhelm, Steven W; Brussaard, Corina P D

2016-02-01

Viral lysis of phytoplankton constrains marine primary production, food web dynamics and biogeochemical cycles in the ocean. Yet, little is known about the biogeographical distribution of viral lysis rates across the global ocean. To address this, we investigated phytoplankton group-specific viral lysis rates along a latitudinal gradient within the North Atlantic Ocean. The data show large-scale distribution patterns of different virus groups across the North Atlantic that are associated with the biogeographical distributions of their potential microbial hosts. Average virus-mediated lysis rates of the picocyanobacteria Prochlorococcus and Synechococcus were lower than those of the picoeukaryotic and nanoeukaryotic phytoplankton (that is, 0.14 per day compared with 0.19 and 0.23 per day, respectively). Total phytoplankton mortality (virus plus grazer-mediated) was comparable to the gross growth rate, demonstrating high turnover rates of phytoplankton populations. Virus-induced mortality was an important loss process at low and mid latitudes, whereas phytoplankton mortality was dominated by microzooplankton grazing at higher latitudes (>56°N). This shift from a viral-lysis-dominated to a grazing-dominated phytoplankton community was associated with a decrease in temperature and salinity, and the decrease in viral lysis rates was also associated with increased vertical mixing at higher latitudes. Ocean-climate models predict that surface warming will lead to an expansion of the stratified and oligotrophic regions of the world's oceans. Our findings suggest that these future shifts in the regional climate of the ocean surface layer are likely to increase the contribution of viral lysis to phytoplankton mortality in the higher-latitude waters of the North Atlantic, which may potentially reduce transfer of matter and energy up the food chain and thus affect the capacity of the northern North Atlantic to act as a long-term sink for CO2.

An overview of the South Atlantic Ocean climate variability and air-sea interaction processes

NASA Astrophysics Data System (ADS)

Pezzi, L. P.; Parise, C. K.; Souza, R.; Gherardi, D. F.; Camargo, R.; Soares, H. C.; Silveira, I.

2013-05-01

The Ocean Modeling Group at the National Institute of Space Research (INPE) in Brazil has been developing several studies to understand the role of the Atlantic ocean on the South America climate. Studies include simulating the dynamics of the Tropical South-Atlantic Ocean and Southern Ocean. This is part of an ongoing international cooperation, in which Brazil participates with in situ observations, numerical modeling and statistical analyses. We have focused on the understanding of the impacts of extreme weather events over the Tropical South Atlantic Ocean and their prediction on different time-scales. One such study is aimed at analyzing the climate signal generated by imposing an extreme condition on the Antarctic sea ice and considering different complexities of the sea ice model. The influence of the Brazil-Malvinas Confluence (BMC) region on the marine atmospheric boundary layer (MABL) is also investigated through in situ data analysis of different cruises and numerical experiments with a regional numerical model. There is also an ongoing investigation that revealed basin-scale interannual climate variation with impacts on the Brazilian Large Marine Ecosystems (LMEs), which are strongly correlated with climate indices such as ENSO, AAO and PDO.

Coupled ocean-shelf ecosystem modelling of northern North Atlantic

NASA Astrophysics Data System (ADS)

Harle, J.; Holt, J. T.; Butenschön, M.; Allen, J. I.

2016-02-01

The biogeochemistry and ecosystems of the open-ocean and shelf seas are intimately connected. For example Northwest European continental shelf receives a substantial fraction of its nutrients from the wider North Atlantic and exports carbon at depth, sequestering it from atmospheric exchange. In the EC FP7 EuroBasin project (Holt et al 2014) we have developed a 1/12 degree basin-scale NEMO-ERSEM model with specific features relevant to shelf seas (e.g. tides and advanced vertical mixing schemes). This model is eddy resolving in the open-ocean, and resolves barotropic scales on-shelf. We use this model to explore the interaction between finely resolved physical processes and the ecosystem. Here we focus on shelf-sea processes and the connection between the shelf seas and open-ocean, and compare results with a 1/4 degree (eddy permitting) model that does not include shelf sea processes. We find tidal mixing fronts and river plume are well represented in the 1/12 degree model. Using approaches developed for the NW Shelf (Holt et al 2012), we provide estimates of across-shelf break nutrient fluxes to the seas surrounding this basin, and relate these fluxes and their interannual variability to the physical processes driving ocean-shelf exchange. Holt, J., et al, 2012. Oceanic controls on the primary production of the northwest European continental shelf: model experiments under recent past conditions and a potential future scenario. Biogeosciences 9, 97-117. Holt, J., et al, 2014. Challenges in integrative approaches to modelling the marine ecosystems of the North Atlantic: Physics to Fish and Coasts to Ocean. Progress in Oceanography doi:10.1016/j.pocean.2014.04.024.

Ocean Dynamics in the Key Regions of North Atlantic-Arctic Exchanges: Evaluation of Global Multi-Resolution FESOM and CMIP-type INMCM Models with Long-Term Observations

NASA Astrophysics Data System (ADS)

Beszczynska-Moeller, A.; Gürses, Ö.; Sidorenko, D.; Goessling, H.; Volodin, E. M.; Gritsun, A.; Iakovlev, N. G.; Andrzejewski, J.

2017-12-01

Enhancing the fidelity of climate models in the Arctic and North Atlantic in order to improve Arctic predictions requires better understanding of the underlying causes of common biases. The main focus of the ERA.Net project NAtMAP (Amending North Atlantic Model Biases to Improve Arctic Predictions) is on the dynamics of the key regions connecting the Arctic and the North Atlantic climate. The study aims not only at increased model realism, but also at a deeper understanding of North Atlantic-Arctic links and their contribution to Arctic predictability. Two complementary approaches employing different global coupled climate models, ECHAM6-FESOM and INMCM4/5, were adopted. The first approach is based on a recent development of climate models with ocean components based on unstructured meshes, allowing to resolve eddies and narrow boundary currents in the most crucial regions while keeping a moderate resolution elsewhere. The multi-resolution sea ice-ocean component of ECHAM6-FESOM allows studying the benefits of very high resolution in key areas of the North Atlantic. An alternative approach to address the North Atlantic and Arctic biases is also tried by tuning the performance of the relevant sub-grid-scale parameterizations in eddy resolving version the CMIP5 climate model INMCM4. Using long-term in situ and satellite observations and available climatologies we attempt to evaluate to what extent a higher resolution, allowing the explicit representation of eddies and narrow boundary currents in the North Atlantic and Nordic Seas, can alleviate the common model errors. The effects of better resolving the Labrador Sea area on reducing the model bias in surface hydrography and improved representation of ocean currents are addressed. Resolving eddy field in the Greenland Sea is assessed in terms of reducing the deep thermocline bias. The impact of increased resolution on the modeled characteristics of Atlantic water transport into the Arctic is examined with a special

Tropical Atlantic Impacts on the Decadal Climate Variability of the Tropical Ocean and Atmosphere.

NASA Astrophysics Data System (ADS)

Li, X.; Xie, S. P.; Gille, S. T.; Yoo, C.

2015-12-01

Previous studies revealed atmospheric bridges between the tropical Pacific, Atlantic, and Indian Ocean. In particular, several recent works indicate that the Atlantic sea surface temperature (SST) may contribute to the climate variability over the equatorial Pacific. Inspired by these studies, our work aims at investigating the impact of the tropical Atlantic on the entire tropical climate system, and uncovering the physical dynamics under these tropical teleconnections. We first performed a 'pacemaker' simulation by restoring the satellite era tropical Atlantic SST changes in a fully coupled model - the CESM1. Results reveal that the Atlantic warming heats the Indo-Western Pacific and cools the Eastern Pacific, enhances the Walker circulation and drives the subsurface Pacific to a La Niña mode, contributing to 60-70% of the above tropical changes in the past 30 years. The same pan-tropical teleconnections have been validated by the statistics of observations and 106 CMIP5 control simulations. We then used a hierarchy of atmospheric and oceanic models with different complexities, to single out the roles of atmospheric dynamics, atmosphere-ocean fluxes, and oceanic dynamics in these teleconnections. With these simulations we established a two-step mechanism as shown in the schematic figure: 1) Atlantic warming generates an atmospheric deep convection and induces easterly wind anomalies over the Indo-Western Pacific in the form of Kelvin waves, and westerly wind anomalies over the eastern equatorial Pacific as Rossby waves, in line with Gill's solution. This circulation changes warms the Indo-Western Pacific and cools the Eastern Pacific with the wind-evaporation-SST effect, forming a temperature gradient over the Indo-Pacific basins. 2) The temperature gradient further generates a secondary atmospheric deep convection, which reinforces the easterly wind anomalies over the equatorial Pacific and enhances the Walker circulation, triggering the Pacific to a La Ni

33 CFR 165.511 - Security Zone; Atlantic Ocean, Chesapeake & Delaware Canal, Delaware Bay, Delaware River and its...

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Security Zone; Atlantic Ocean, Chesapeake & Delaware Canal, Delaware Bay, Delaware River and its tributaries. 165.511 Section 165.511... Limited Access Areas Fifth Coast Guard District § 165.511 Security Zone; Atlantic Ocean, Chesapeake...

33 CFR 165.511 - Security Zone; Atlantic Ocean, Chesapeake & Delaware Canal, Delaware Bay, Delaware River and its...

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Security Zone; Atlantic Ocean, Chesapeake & Delaware Canal, Delaware Bay, Delaware River and its tributaries. 165.511 Section 165.511... Limited Access Areas Fifth Coast Guard District § 165.511 Security Zone; Atlantic Ocean, Chesapeake...

33 CFR 165.511 - Security Zone; Atlantic Ocean, Chesapeake & Delaware Canal, Delaware Bay, Delaware River and its...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Security Zone; Atlantic Ocean, Chesapeake & Delaware Canal, Delaware Bay, Delaware River and its tributaries. 165.511 Section 165.511... Limited Access Areas Fifth Coast Guard District § 165.511 Security Zone; Atlantic Ocean, Chesapeake...

33 CFR 165.511 - Security Zone; Atlantic Ocean, Chesapeake & Delaware Canal, Delaware Bay, Delaware River and its...

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Security Zone; Atlantic Ocean, Chesapeake & Delaware Canal, Delaware Bay, Delaware River and its tributaries. 165.511 Section 165.511... Limited Access Areas Fifth Coast Guard District § 165.511 Security Zone; Atlantic Ocean, Chesapeake...

33 CFR 165.511 - Security Zone; Atlantic Ocean, Chesapeake & Delaware Canal, Delaware Bay, Delaware River and its...

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Security Zone; Atlantic Ocean, Chesapeake & Delaware Canal, Delaware Bay, Delaware River and its tributaries. 165.511 Section 165.511... Limited Access Areas Fifth Coast Guard District § 165.511 Security Zone; Atlantic Ocean, Chesapeake...

The increasing control of the Atlantic Ocean on ENSO after the early 1990s

NASA Astrophysics Data System (ADS)

Yu, J. Y.; Paek, H.; Wang, L.; Lyu, K.

2016-12-01

The El Niño-Southern Oscillation (ENSO) is the most powerful interannual variability in Earth's climate system. Previous studies have emphasized processes within the tropical Pacific or Indian Oceans for the generation of ENSO. Recent studies have increasingly suggested that the Atlantic Ocean may play an active role in forcing ENSO variability. In this talk, we will present evidence from observational analyses and modeling experiments to show that the Atlantic Ocean became more capable of influencing ENSO properties after the Atlantic Multidecadal Oscillation (AMO) changed to its positive phase in the early-1990s. A wave source mechanism is proposed to explain how the positive phase of the AMO can intensify the North Pacific Subtropical High (NPSH) to change the ENSO from the Eastern Pacific (EP) type to the Central Pacific (CP) type. A sequence of processes are identified to suggest that the AMO can displace the Pacific Walker circulation, induce a wave source in the tropical central Pacific, and excite a barotropic wave train toward higher-latitudes to enhance the NPSH, which then triggers subtropical Pacific atmospheric forcing and atmosphere-ocean coupling to increase the occurrence of the CP ENSO. An Atlantic capacitor mechanism is also proposed to explain how the positive phase of the AMO can intensify the quasi-biennial (QB) component of ENSO resulting in a more frequent occurrence of ENSO events. We will show that the capacitor mechanism works only after the AMO warmed up the Atlantic sea surface temperatures after the early-1990s. The increased feedback from the Atlantic to the Pacific has enabled the Atlantic capacitor mechanism to intensify the biennial variability in the Pacific during the past two decades. Our suggestion is very different from the previous prevailing views that have emphasized the Indo-Pacific Oceans as the pacemaker for the biennial variability in ENSO. The increasing control of the Atlantic has enabled the CP ENSO dynamics to

Thermal evolution of the western South Atlantic and the adjacent continent during Termination 1

NASA Astrophysics Data System (ADS)

Chiessi, C. M.; Mulitza, S.; Mollenhauer, G.; Silva, J. B.; Groeneveld, J.; Prange, M.

2015-06-01

During Termination 1, millennial-scale weakening events of the Atlantic meridional overturning circulation (AMOC) supposedly produced major changes in sea surface temperatures (SSTs) of the western South Atlantic, and in mean air temperatures (MATs) over southeastern South America. It has been suggested, for instance, that the Brazil Current (BC) would strengthen (weaken) and the North Brazil Current (NBC) would weaken (strengthen) during slowdown (speed-up) events of the AMOC. This anti-phase pattern was claimed to be a necessary response to the decreased North Atlantic heat piracy during periods of weak AMOC. However, the thermal evolution of the western South Atlantic and the adjacent continent is so far largely unknown. Here we address this issue, presenting high-temporal-resolution SST and MAT records from the BC and southeastern South America, respectively. We identify a warming in the western South Atlantic during Heinrich Stadial 1 (HS1), which is followed first by a drop and then by increasing temperatures during the Bølling-Allerød, in phase with an existing SST record from the NBC. Additionally, a similar SST evolution is shown by a southernmost eastern South Atlantic record, suggesting a South Atlantic-wide pattern in SST evolution during most of Termination 1. Over southeastern South America, our MAT record shows a two-step increase during Termination 1, synchronous with atmospheric CO2 rise (i.e., during the second half of HS1 and during the Younger Dryas), and lagging abrupt SST changes by several thousand years. This delay corroborates the notion that the long duration of HS1 was fundamental in driving the Earth out of the last glacial.

Thermal evolution of the western South Atlantic and the adjacent continent during Termination 1

NASA Astrophysics Data System (ADS)

Chiessi, C. M.; Mulitza, S.; Mollenhauer, G.; Silva, J. B.; Groeneveld, J.; Prange, M.

2014-12-01

During Termination 1, millennial-scale weakening events of the Atlantic meridional overturning circulation (AMOC) supposedly produced major changes in sea surface temperatures (SST) of the western South Atlantic, and in mean air temperatures (MAT) over southeastern South America. It was suggested, for instance, that the Brazil Current (BC) would strengthen (weaken) and the North Brazil Current (NBC) would weaken (strengthen) during slowdown (speed-up) events of the AMOC. This anti-phase pattern was claimed to be a necessary response to the decreased North Atlantic heat piracy during periods of weak AMOC. However, the thermal evolution of the western South Atlantic and the adjacent continent is largely unknown and a compelling record of the BC-NBC anti-phase behavior remains elusive. Here we address this issue, presenting high temporal resolution SST and MAT records from the BC and southeastern South America, respectively. We identify a warming in the western South Atlantic during Heinrich Stadial 1 (HS1), which is followed first by a drop and then by increasing temperatures during the Bølling-Allerød, in-phase with an existing NBC record. Additionally, a similar SST evolution is shown by a southernmost eastern South Atlantic record, suggesting a South Atlantic-wide pattern in SST evolution during most of Termination 1. Over southeastern South America, our MAT record shows a two-step increase during Termination 1, synchronous with atmospheric CO2 rise (i.e., during the second half of HS1 and during the Younger Dryas), and lagging abrupt SST changes by several thousand years. This delay corroborates the notion that the long duration of HS1 was fundamental to drive the Earth out of the last glacial.

Development of Automated Whistle and Click Classifiers for Odontocete Species in the Western Atlantic Ocean and the Waters Surrounding the Hawaiian Islands

DTIC Science & Technology

2015-09-30

for Odontocete Species in the Western Atlantic Ocean and the Waters Surrounding the Hawaiian Islands Julie N. Oswald & Tina M. Yack Bio-Waves... Atlantic Ocean, the temperate Pacific Ocean and the waters surrounding the Hawaiian Islands. These classifiers will also incorporate ancillary...and echolocation click classifiers for odontocete species in the northwest Atlantic Ocean, the waters surrounding the Hawaiian Islands and the

Population structure of humpback whales from their breeding grounds in the South Atlantic and Indian Oceans.

PubMed

Rosenbaum, Howard C; Pomilla, Cristina; Mendez, Martin; Leslie, Matthew S; Best, Peter B; Findlay, Ken P; Minton, Gianna; Ersts, Peter J; Collins, Timothy; Engel, Marcia H; Bonatto, Sandro L; Kotze, Deon P G H; Meÿer, Mike; Barendse, Jaco; Thornton, Meredith; Razafindrakoto, Yvette; Ngouessono, Solange; Vely, Michel; Kiszka, Jeremy

2009-10-08

Although humpback whales are among the best-studied of the large whales, population boundaries in the Southern Hemisphere (SH) have remained largely untested. We assess population structure of SH humpback whales using 1,527 samples collected from whales at fourteen sampling sites within the Southwestern and Southeastern Atlantic, the Southwestern Indian Ocean, and Northern Indian Ocean (Breeding Stocks A, B, C and X, respectively). Evaluation of mtDNA population structure and migration rates was carried out under different statistical frameworks. Using all genetic evidence, the results suggest significant degrees of population structure between all ocean basins, with the Southwestern and Northern Indian Ocean most differentiated from each other. Effective migration rates were highest between the Southeastern Atlantic and the Southwestern Indian Ocean, followed by rates within the Southeastern Atlantic, and the lowest between the Southwestern and Northern Indian Ocean. At finer scales, very low gene flow was detected between the two neighbouring sub-regions in the Southeastern Atlantic, compared to high gene flow for whales within the Southwestern Indian Ocean. Our genetic results support the current management designations proposed by the International Whaling Commission of Breeding Stocks A, B, C, and X as four strongly structured populations. The population structure patterns found in this study are likely to have been influenced by a combination of long-term maternally directed fidelity of migratory destinations, along with other ecological and oceanographic features in the region.

Population Structure of Humpback Whales from Their Breeding Grounds in the South Atlantic and Indian Oceans

PubMed Central

Rosenbaum, Howard C.; Pomilla, Cristina; Mendez, Martin; Leslie, Matthew S.; Best, Peter B.; Findlay, Ken P.; Minton, Gianna; Ersts, Peter J.; Collins, Timothy; Engel, Marcia H.; Bonatto, Sandro L.; Kotze, Deon P. G. H.; Meÿer, Mike; Barendse, Jaco; Thornton, Meredith; Razafindrakoto, Yvette; Ngouessono, Solange; Vely, Michel; Kiszka, Jeremy

2009-01-01

Although humpback whales are among the best-studied of the large whales, population boundaries in the Southern Hemisphere (SH) have remained largely untested. We assess population structure of SH humpback whales using 1,527 samples collected from whales at fourteen sampling sites within the Southwestern and Southeastern Atlantic, the Southwestern Indian Ocean, and Northern Indian Ocean (Breeding Stocks A, B, C and X, respectively). Evaluation of mtDNA population structure and migration rates was carried out under different statistical frameworks. Using all genetic evidence, the results suggest significant degrees of population structure between all ocean basins, with the Southwestern and Northern Indian Ocean most differentiated from each other. Effective migration rates were highest between the Southeastern Atlantic and the Southwestern Indian Ocean, followed by rates within the Southeastern Atlantic, and the lowest between the Southwestern and Northern Indian Ocean. At finer scales, very low gene flow was detected between the two neighbouring sub-regions in the Southeastern Atlantic, compared to high gene flow for whales within the Southwestern Indian Ocean. Our genetic results support the current management designations proposed by the International Whaling Commission of Breeding Stocks A, B, C, and X as four strongly structured populations. The population structure patterns found in this study are likely to have been influenced by a combination of long-term maternally directed fidelity of migratory destinations, along with other ecological and oceanographic features in the region. PMID:19812698

Detection of Intermediate Mediterranean Waters in the Atlantic Ocean by ARGO Floats Data

NASA Astrophysics Data System (ADS)

Filyushkin, B. N.; Lebedev, K. V.; Kozhelupova, N. G.

2017-11-01

Peculiarities of the spatial distribution of intermediate Mediterranean waters (MW), which are the main source to maintain the heat and salt budgets at depths of 600-1500 m in the Atlantic Ocean, have been studied using the ARGO floats measurements database. About 75000 temperature and salinity profiles recorded by 900 ARGO floats in 2005-2014 in the Atlantic Ocean for latitudes from 20° to 50° N were used. To process these data, we used the ARGO-Based Model for Investigation of the Global Ocean (AMIGO). This technique allowed us for the first time to obtain a complete set of oceanographic characteristics up to a depth of 2000 m for different time averaging intervals (month, season, years). Joint analysis of the temperature, salinity, and velocity distributions at 700-1000 m depths made it possible to revise the distribution of MW and their penetration into the western part of the ocean across the Mid-Atlantic Ridge (MAR). It is shown that at depths of 700 and 1000 m, the Mid-Atlantic Ridge is a barrier to advective propagation of salty waters (>35.5 PSU) to the west and is transparent to fragments of destroyed intrathermocline lenses (ITL) with lower salinity (<35.4 PSU). In the Atlantic region, from 20° to 35° N and from 30° to 70° W, individual lens profiles with an anomalous salinity distribution were sought using ARGO measurements to detect ITL and its separate fragments. About 24 000 measurements from 370 ARGO floats were analyzed, and only about 3% of them showed weak salinity anomalies at 800-1200 m depths. No ITL were found from these observations. Analysis of long-term drifting of individual floats recording temperature and salinity profiles with anomalous layers made it possible to study the nature of MW transport through the MAR.

The impacts of oceanic deep temperature perturbations in the North Atlantic on decadal climate variability and predictability

NASA Astrophysics Data System (ADS)

Germe, Agathe; Sévellec, Florian; Mignot, Juliette; Fedorov, Alexey; Nguyen, Sébastien; Swingedouw, Didier

2017-12-01

Decadal climate predictability in the North Atlantic is largely related to ocean low frequency variability, whose sensitivity to initial conditions is not very well understood. Recently, three-dimensional oceanic temperature anomalies optimally perturbing the North Atlantic Mean Temperature (NAMT) have been computed via an optimization procedure using a linear adjoint to a realistic ocean general circulation model. The spatial pattern of the identified perturbations, localized in the North Atlantic, has the largest magnitude between 1000 and 4000 m depth. In the present study, the impacts of these perturbations on NAMT, on the Atlantic meridional overturning circulation (AMOC), and on climate in general are investigated in a global coupled model that uses the same ocean model as was used to compute the three-dimensional optimal perturbations. In the coupled model, these perturbations induce AMOC and NAMT anomalies peaking after 5 and 10 years, respectively, generally consistent with the ocean-only linear predictions. To further understand their impact, their magnitude was varied in a broad range. For initial perturbations with a magnitude comparable to the internal variability of the coupled model, the model response exhibits a strong signature in sea surface temperature and precipitation over North America and the Sahel region. The existence and impacts of these ocean perturbations have important implications for decadal prediction: they can be seen either as a source of predictability or uncertainty, depending on whether the current observing system can detect them or not. In fact, comparing the magnitude of the imposed perturbations with the uncertainty of available ocean observations such as Argo data or ocean state estimates suggests that only the largest perturbations used in this study could be detectable. This highlights the importance for decadal climate prediction of accurate ocean density initialisation in the North Atlantic at intermediate and greater

North Atlantic ocean circulation and abrupt climate change during the last glaciation.

PubMed

Henry, L G; McManus, J F; Curry, W B; Roberts, N L; Piotrowski, A M; Keigwin, L D

2016-07-29

The most recent ice age was characterized by rapid and hemispherically asynchronous climate oscillations, whose origin remains unresolved. Variations in oceanic meridional heat transport may contribute to these repeated climate changes, which were most pronounced during marine isotope stage 3, the glacial interval 25 thousand to 60 thousand years ago. We examined climate and ocean circulation proxies throughout this interval at high resolution in a deep North Atlantic sediment core, combining the kinematic tracer protactinium/thorium (Pa/Th) with the deep water-mass tracer, epibenthic δ(13)C. These indicators suggest reduced Atlantic overturning circulation during every cool northern stadial, with the greatest reductions during episodic Hudson Strait iceberg discharges, while sharp northern warming followed reinvigorated overturning. These results provide direct evidence for the ocean's persistent, central role in abrupt glacial climate change. Copyright © 2016, American Association for the Advancement of Science.

Mercury-Atlas 6 spacecraft retrieved from Atlantic Ocean following mission

NASA Technical Reports Server (NTRS)

1962-01-01

The Mercury-Atlas 6 'Friendship 7' spacecraft is retrieved from the Atlantic Ocean following Astronaut John H. Glenn Jr.'s three-orbit space mission. In this view, the capsule is still in the water, with retrieval cable connected to it.

Seasonal re-emergence of North Atlantic subsurface ocean temperature anomalies and Northern hemisphere climate

NASA Astrophysics Data System (ADS)

Sinha, Bablu; Blaker, Adam; Duchez, Aurelie; Grist, Jeremy; Hewitt, Helene; Hirschi, Joel; Hyder, Patrick; Josey, Simon; Maclachlan, Craig; New, Adrian

2017-04-01

A high-resolution coupled ocean atmosphere model is used to study the effects of seasonal re-emergence of North Atlantic subsurface ocean temperature anomalies on northern hemisphere winter climate. A 50-member control simulation is integrated from September 1 to 28 February and compared with a similar ensemble with perturbed ocean initial conditions. The perturbation consists of a density-compensated subsurface (deeper than 180m) temperature anomaly corresponding to the observed subsurface temperature anomaly for September 2010, which is known to have re-emerged at the ocean surface in subsequent months. The perturbation is confined to the North Atlantic Ocean between the Equator and 65 degrees North. The model has 1/4 degree horizontal resolution in the ocean and the experiment is repeated for two atmosphere horizontal resolutions ( 60km and 25km) in order to determine whether the sensitivity of the atmosphere to re-emerging temperature anomalies is dependent on resolution. The ensembles display a wide range of reemergence behaviour, in some cases re-emergence occurs by November, in others it is delayed or does not occur at all. A wide range of amplitudes of the re-emergent temperature anomalies is observed. In cases where re-emergence occurs, there is a marked effect on both the regional (North Atlantic and Europe) and hemispheric surface pressure and temperature patterns. The results highlight a potentially important process whereby ocean memory of conditions up to a year earlier can significantly enhance seasonal forecast skill.

Tenarife Island, Canary Island Archipelago, Atlantic Ocean

NASA Technical Reports Server (NTRS)

1991-01-01

Tenarife Island is one of the most volcanically active of the Canary Island archipelago, Atlantic Ocean, just off the NW coast of Africa, (28.5N, 16.5W). The old central caldera, nearly filled in by successive volcanic activity culminating in two stratocones. From those two peaks, a line of smaller cinder cones extend to the point of the island. Extensive gullies dissect the west side of the island and some forests still remain on the east side.

Tenarife Island, Canary Island Archipelago, Atlantic Ocean

NASA Image and Video Library

1991-08-11

Tenarife Island is one of the most volcanically active of the Canary Island archipelago, Atlantic Ocean, just off the NW coast of Africa, (28.5N, 16.5W). The old central caldera, nearly filled in by successive volcanic activity culminating in two stratocones. From those two peaks, a line of smaller cinder cones extend to the point of the island. Extensive gullies dissect the west side of the island and some forests still remain on the east side.

Hurricane Bonnie, Northeast of Bermuda, Atlantic Ocean

NASA Technical Reports Server (NTRS)

1992-01-01

Hurricane Bonnie was over the North Atlantic Ocean about 500 miles northeast of Bermuda (39.0N, 56.5W) when this photo was taken. Compare this view with Hurricane Iniki, also photographed on this mission (STS-47-77-058). Bonnie is small but in her prime, having a well defined eye, a tight spiral gyre indicating high wind speeds and numerous thunderheads. Iniki, on the other hand, was decaying when photographed and no longer presented a threat.

Causes of Upper-Ocean Temperature Anomalies in the Tropical North Atlantic

NASA Astrophysics Data System (ADS)

Rugg, A.; Foltz, G. R.; Perez, R. C.

2016-02-01

Hurricane activity and regional rainfall are strongly impacted by upper ocean conditions in the tropical North Atlantic, defined as the region between the equator and 20°N. A previous study analyzed a strong cold sea surface temperature (SST) anomaly that developed in this region during early 2009 and was recorded by the Pilot Research Array in the Tropical Atlantic (PIRATA) moored buoy at 4°N, 23°W (Foltz et al. 2012). The same mooring shows a similar cold anomaly in the spring of 2015 as well as a strong warm anomaly in 2010, offering the opportunity for a more comprehensive analysis of the causes of these events. In this study we examine the main causes of the observed temperature anomalies between 1998 and 2015. Basin-scale conditions during these events are analyzed using satellite SST, wind, and rain data, as well as temperature and salinity profiles from the NCEP Global Ocean Data Assimilation System. A more detailed analysis is conducted using ten years of direct measurements from the PIRATA mooring at 4°N, 23°W. Results show that the cooling and warming anomalies were caused primarily by wind-driven changes in surface evaporative cooling, mixed layer depth, and upper-ocean vertical velocity. Anomalies in surface solar radiation acted to damp the wind-driven SST anomalies in the latitude bands of the ITCZ (3°-8°N). Basin-scale analyses also suggest a strong connection between the observed SST anomalies and the Atlantic Meridional Mode, a well-known pattern of SST and surface wind anomalies spanning the tropical Atlantic.

Interannual to Decadal Variability of Atlantic Water in the Nordic and Adjacent Seas

NASA Technical Reports Server (NTRS)

Carton, James A.; Chepurin, Gennady A.; Reagan, James; Haekkinen, Sirpa

2011-01-01

Warm salty Atlantic Water is the main source water for the Arctic Ocean and thus plays an important role in the mass and heat budget of the Arctic. This study explores interannual to decadal variability of Atlantic Water properties in the Nordic Seas area where Atlantic Water enters the Arctic, based on a reexamination of the historical hydrographic record for the years 1950-2009, obtained by combining multiple data sets. The analysis shows a succession of four multi-year warm events where temperature anomalies at 100m depth exceed 0.4oC, and three cold events. Three of the four warm events lasted 3-4 years, while the fourth began in 1999 and persists at least through 2009. This most recent warm event is anomalous in other ways as well, being the strongest, having the broadest geographic extent, being surface-intensified, and occurring under exceptional meteorological conditions. Three of the four warm events were accompanied by elevated salinities consistent with enhanced ocean transport into the Nordic Seas, with the exception of the event spanning July 1989-July 1993. Of the three cold events, two lasted for four years, while the third lasted for nearly 14 years. Two of the three cold events are associated with reduced salinities, but the cold event of the 1960s had elevated salinities. The relationship of these events to meteorological conditions is examined. The results show that local surface heat flux variations act in some cases to reinforce the anomalies, but are too weak to be the sole cause.

Land-atmosphere-ocean interactions in the southeastern Atlantic: interannual variability

NASA Astrophysics Data System (ADS)

Sun, Xiaoming; Vizy, Edward K.; Cook, Kerry H.

2018-02-01

Land-atmosphere-ocean interactions in the southeastern South Atlantic and their connections to interannual variability are examined using a regional climate model coupled with an intermediate-level ocean model. In austral summer, zonal displacements of the South Atlantic subtropical high (SASH) can induce variations of mixed-layer currents in the Benguela upwelling region through surface wind stress curl anomalies near the Namibian coast, and an eastward shifted SASH is related to the first Pacific-South American mode. When the SASH is meridionally displaced, mixed layer vertically-integrated Ekman transport anomalies are mainly a response to the change of alongshore surface wind stress. The latitudinal shift of the SASH tends to dampen the anomalous alongshore wind by modulating the land-sea thermal contrast, while opposed by oceanic diffusion. Although the position of the SASH is closely linked to the phase of El Niño-Southern Oscillation (ENSO) and the southern annular mode (SAM) in austral summer, an overall relationship between Benguela upwelling strength and ENSO or SAM is absent. During austral winter, variations of the mixed layer Ekman transport in the Benguela upwelling region are connected to the strength of the SASH through its impact on both coastal wind stress curl and alongshore surface wind stress. Compared with austral summer, low-level cloud cover change plays a more important role. Although wintertime sea surface temperature fluctuations in the equatorial Atlantic are strong and may act to influence variability over the northern Benguela area, the surface heat budget analysis suggests that local air-sea interactions dominate.

Cloud formation over Western Atlantic Ocean north of South America

NASA Image and Video Library

1962-10-03

S62-06606 (3 Oct. 1962) --- Cloud formation over Western Atlantic Ocean north of South America taken during the fourth orbit pass of the Mercury-Atlas 8 (MA-8) mission by astronaut Walter M. Schirra Jr. with a hand-held camera. Photo credit: NASA

Sources of Meridional Heat and Freshwater Transport Anomalies in the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Kelly, K. A.; Thompson, L.; Drushka, K.

2016-02-01

Observations of thermosteric and halosteric sea level from hydrographic data, ocean mass from GRACE and altimetric sea surface height are used to infer meridional heat transport (MHT) and freshwater convergence (FWC) anomalies for the Atlantic Ocean for 1993-2014. A Kalman filter extracts smooth estimates of heat transport convergence (HTC) and FWC from discrepancies between the sea level response to monthly surface heat and freshwater fluxes and observed heat and freshwater content in each of eight regions. Estimates of MHT anomalies are derived by summing the HTC from north to south and adding an integration constant derived from updated MHT estimates at 41N (Willis 2010). MHT estimates are relatively insensitive to the choice of heat flux products and are highly coherent spatially. Anomalies in MHT are comparable to those observed at the RAPID/MOCHA line at 26.5N and show a continued recovery from the minimum in 2010 throughout the Atlantic. MHT anomalies resemble estimates of Agulhas Leakage derived from altimeter (LeBars et al 2014) suggesting that the Indian Ocean is the source of the anomalous heat inflow. FWC estimates are also insensitive to choice of flux products. Interannual anomalies of FWC integrated from 67N to 35S resemble estimates of Atlantic river inflow (de Couet and Maurer, GRDC 2009), whereas the trend is consistent with estimates of freshwater input from Greenland. Increasing values of FWC after 2002 at a time when MHT was decreasing may indicate a feedback between the Atlantic Meridional Overturning Circulation and FWC that would accelerate the AMOC slowdown.

Decadal change of the south Atlantic ocean Angola-Benguela frontal zone since 1980

NASA Astrophysics Data System (ADS)

Vizy, Edward K.; Cook, Kerry H.; Sun, Xiaoming

2018-01-01

High-resolution simulations with a regional atmospheric model coupled to an intermediate-level mixed layer ocean model along with multiple atmospheric and oceanic reanalyses are analyzed to understand how and why the Angola-Benguela frontal Zone (ABFZ) has changed since 1980. A southward shift of 0.05°-0.55° latitude decade-1 in the annual mean ABFZ position accompanied by an intensification of + 0.05 to + 0.13 K/100-km decade-1 has occurred as ocean mixed layer temperatures have warmed (cooled) equatorward (poleward) of the front over the 1980-2014 period. These changes are captured in a 35-year model integration. The oceanic warming north of the ABFZ is associated with a weakening of vertical entrainment, reduced cooling associated with vertical diffusion, and a deepening of the mixed layer along the Angola coast. These changes coincide with a steady weakening of the onshore atmospheric flow as the zonal pressure gradient between the eastern equatorial Atlantic and the Congo Basin weakens. Oceanic cooling poleward of the ABFZ is primarily due to enhanced advection of cooler water from the south and east, increased cooling by vertical diffusion, and shoaling of the mixed layer depth. In the atmosphere, these changes are related to an intensification and poleward shift of the South Atlantic sub-tropical anticyclone as surface winds, hence the westward mixed layer ocean currents, intensify in the Benguela upwelling region along the Namibian coast. With a few caveats, these findings demonstrate that air/sea interactions play a prominent role in influencing the observed decadal variability of the ABFZ over the southeastern Atlantic since 1980.

Mid-Pliocene planktic foraminifer assemblage of the North Atlantic Ocean

USGS Publications Warehouse

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

2007-01-01

The US Geological Survey Pliocene Research, Interpretation and Synoptic Mapping (PRISM) North Atlantic faunal data set provides a unique, temporally constrained perspective to document and evaluate the quantitative geographic distribution of key mid-Pliocene taxa. Planktic foraminifer census data from within the PRISM time slab (3.29 to 2.97 Ma) at thirteen sites in the North Atlantic Ocean have been analyzed. We have compiled Scanning Electron Micrographs for an atlas of mid-Pliocene assemblages from the North Atlantic with descriptions of each taxon to document the taxonomic concepts that accompany the PRISM data. In mid-Pliocene assemblages, the geographic distributions of extant taxa are similar to their present day distributions, although some are extended to the north. We use the distribution of extinct taxa to assess previous assumptions regarding environmental preferences.

33 CFR 334.400 - Atlantic Ocean south of entrance to Chesapeake Bay off Camp Pendleton, Virginia; naval restricted...

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Atlantic Ocean south of entrance to Chesapeake Bay off Camp Pendleton, Virginia; naval restricted area. 334.400 Section 334.400... AND RESTRICTED AREA REGULATIONS § 334.400 Atlantic Ocean south of entrance to Chesapeake Bay off Camp...

33 CFR 334.400 - Atlantic Ocean south of entrance to Chesapeake Bay off Camp Pendleton, Virginia; naval restricted...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Atlantic Ocean south of entrance to Chesapeake Bay off Camp Pendleton, Virginia; naval restricted area. 334.400 Section 334.400... AND RESTRICTED AREA REGULATIONS § 334.400 Atlantic Ocean south of entrance to Chesapeake Bay off Camp...

33 CFR 334.400 - Atlantic Ocean south of entrance to Chesapeake Bay off Camp Pendleton, Virginia; naval restricted...

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Atlantic Ocean south of entrance to Chesapeake Bay off Camp Pendleton, Virginia; naval restricted area. 334.400 Section 334.400... AND RESTRICTED AREA REGULATIONS § 334.400 Atlantic Ocean south of entrance to Chesapeake Bay off Camp...

33 CFR 334.400 - Atlantic Ocean south of entrance to Chesapeake Bay off Camp Pendleton, Virginia; naval restricted...

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Atlantic Ocean south of entrance to Chesapeake Bay off Camp Pendleton, Virginia; naval restricted area. 334.400 Section 334.400... AND RESTRICTED AREA REGULATIONS § 334.400 Atlantic Ocean south of entrance to Chesapeake Bay off Camp...

33 CFR 334.400 - Atlantic Ocean south of entrance to Chesapeake Bay off Camp Pendleton, Virginia; naval restricted...

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false Atlantic Ocean south of entrance to Chesapeake Bay off Camp Pendleton, Virginia; naval restricted area. 334.400 Section 334.400... AND RESTRICTED AREA REGULATIONS § 334.400 Atlantic Ocean south of entrance to Chesapeake Bay off Camp...

33 CFR 334.500 - St. Johns River, Atlantic Ocean, Sherman Creek; restricted areas and danger zone, Naval Station...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false St. Johns River, Atlantic Ocean... AND RESTRICTED AREA REGULATIONS § 334.500 St. Johns River, Atlantic Ocean, Sherman Creek; restricted areas and danger zone, Naval Station Mayport, Florida. (a) The areas. (1) The St. Johns River restricted...

North Atlantic Deep Water and the World Ocean

NASA Technical Reports Server (NTRS)

Gordon, A. L.

1984-01-01

North Atlantic Deep Water (NADW) by being warmer and more saline than the average abyssal water parcel introduces heat and salt into the abyssal ocean. The source of these properties is upper layer or thermocline water considered to occupy the ocean less dense than sigma-theta of 27.6. That NADW convects even though it's warmer than the abyssal ocean is obviously due to the high salinity. In this way, NADW formation may be viewed as saline convection. The counter force removing heat and salinity (or introducing fresh water) is usually considered to to take place in the Southern Ocean where upwelling deep water is converted to cold fresher Antarctic water masses. The Southern ocean convective process is driven by low temperatures and hence may be considered as thermal convection. A significant fresh water source may also occur in the North Pacific where the northward flowing of abyssal water from the Southern circumpolar belt is saltier and denser than the southward flowing, return abyssal water. The source of the low salinity input may be vertical mixing of the low salinity surface water or the low salinity intermediate water.

NASA Simulation Shows Ocean Turbulence in the North Atlantic

NASA Image and Video Library

2018-02-21

This image shows a simulated snapshot of ocean turbulence in the North Atlantic Ocean in March 2012, from a groundbreaking super-high-resolution global ocean simulation (approximately 1.2 miles, or 2 kilometers, horizontal resolution) developed at JPL (http://wwwcvs.mitgcm.org/viewvc/MITgcm/MITgcm_contrib/llc_hires/llc_4320/). The colors represent the magnitude of surface relative vorticity, a measure of the spin of fluid parcels. The image emphasizes fast-rotating, small-scale (defined here as 6.2 to 31-mile, or 10 to 50 kilometer, range) turbulence, especially during the winter. High levels of relative vorticity caused by small-scale turbulence are believed to strongly transport heat and carbon vertically in the ocean. The image appears in a study (Su et al. 2018), entitled "Ocean submesoscales as a key component of the global heat budget," published recently in Nature Communications. The study suggests that upper-ocean small-scale turbulence transports heat upward in the ocean at a level five times larger than larger-scale heat transport by ocean eddies, significantly affecting the exchange of heat between the ocean interior and atmosphere. Such interactions have a crucial impact on the Earth's climate. A movie is available at https://photojournal.jpl.nasa.gov/catalog/PIA22256

Non-Rayleigh control of upper-ocean Cd isotope fractionation in the western South Atlantic

NASA Astrophysics Data System (ADS)

Xie, Ruifang C.; Galer, Stephen J. G.; Abouchami, Wafa; Rijkenberg, Micha J. A.; de Baar, Hein J. W.; De Jong, Jeroen; Andreae, Meinrat O.

2017-08-01

We present seawater Cd isotopic compositions in five depth profiles and a continuous surface water transect, from 50°S to the Equator, in the western South Atlantic, sampled during GEOTRACES cruise 74JC057 (GA02 section, Leg 3), and investigate the mechanisms governing Cd isotope cycling in the upper and deep ocean. The depth profiles generally display high ε 112 / 110Cd at the surface and decrease with increasing depth toward values typical of Antarctic Bottom Water (AABW). However, at stations north of the Subantarctic Front, the decrease in ε 112 / 110Cd is interrupted by a shift to values intermediate between those of surface and bottom waters, which occurs at depths occupied by North Atlantic Deep Water (NADW). This pattern is associated with variations in Cd concentration from low surface values to a maximum at mid-depths and is attributed to preferential utilization of light Cd by phytoplankton in the surface ocean. Our new results show that in this region Cd-deficient waters do not display the extreme, highly fractionated ε 112 / 110Cd reported in some earlier studies from other oceanic regions. Instead, in the surface and subsurface southwest (SW) Atlantic, when [Cd] drops below 0.1 nmol kg-1, ε 112 / 110Cd are relatively homogeneous and cluster around a value of +3.7, in agreement with the mean value of 3.8 ± 3.3 (2SD, n = 164) obtained from a statistical evaluation of the global ocean Cd isotope dataset. We suggest that Cd-deficient surface waters may acquire their Cd isotope signature via sorption of Cd onto organic ligands, colloids or bacterial/picoplankton extracellular functional groups. Alternatively, we show that an open system, steady-state model is in good accord with the observed Cd isotope systematics in the upper ocean north of the Southern Ocean. The distribution of ε 112 / 110Cd in intermediate and deep waters is consistent with the water mass distribution, with the north-south variations reflecting changes in the mixing proportion

Deglacial Tropical Atlantic subsurface warming links ocean circulation variability to the West African Monsoon.

PubMed

Schmidt, Matthew W; Chang, Ping; Parker, Andrew O; Ji, Link; He, Feng

2017-11-13

Multiple lines of evidence show that cold stadials in the North Atlantic were accompanied by both reductions in Atlantic Meridional Overturning Circulation (AMOC) and collapses of the West African Monsoon (WAM). Although records of terrestrial change identify abrupt WAM variability across the deglaciation, few studies show how ocean temperatures evolved across the deglaciation. To identify the mechanism linking AMOC to the WAM, we generated a new record of subsurface temperature variability over the last 21 kyr based on Mg/Ca ratios in a sub-thermocline dwelling planktonic foraminifera in an Eastern Equatorial Atlantic (EEA) sediment core from the Niger Delta. Our subsurface temperature record shows abrupt subsurface warming during both the Younger Dryas (YD) and Heinrich Event 1. We also conducted a new transient coupled ocean-atmosphere model simulation across the YD that better resolves the western boundary current dynamics and find a strong negative correlation between AMOC strength and EEA subsurface temperatures caused by changes in ocean circulation and rainfall responses that are consistent with the observed WAM change. Our combined proxy and modeling results provide the first evidence that an oceanic teleconnection between AMOC strength and subsurface temperature in the EEA impacted the intensity of the WAM on millennial time scales.

SPURS: Salinity Processes in the Upper-Ocean Regional Study: THE NORTH ATLANTIC EXPERIMENT

NASA Technical Reports Server (NTRS)

Lindstrom, Eric; Bryan, Frank; Schmitt, Ray

2015-01-01

In this special issue of Oceanography, we explore the results of SPURS-1, the first part of the ocean process study Salinity Processes in the Upper-ocean Regional Study (SPURS). The experiment was conducted between August 2012 and October 2013 in the subtropical North Atlantic and was the first of two experiments (SPURS come in pairs!). SPURS-2 is planned for 20162017 in the tropical eastern Pacific Ocean.

A tale of two gyres: Contrasting distributions of dissolved cobalt and iron in the Atlantic Ocean during an Atlantic Meridional Transect (AMT-19)

NASA Astrophysics Data System (ADS)

Shelley, Rachel U.; Wyatt, Neil J.; Tarran, Glenn A.; Rees, Andrew P.; Worsfold, Paul J.; Lohan, Maeve C.

2017-11-01

Cobalt (Co) and iron (Fe) are essential for phytoplankton nutrition, and as such constitute a vital link in the marine biological carbon pump. Atmospheric deposition is an important, and in some places the dominant, source of trace elements (TEs) to the global ocean. Dissolved cobalt (dCo) and iron (dFe) were determined along an Atlantic Meridional Transect (AMT-19; Oct/Nov 2009) between 50°N and 40°S in the upper 150 m in order to investigate the behaviour and distribution of these two essential, bioactive TEs. During AMT-19, large differences in the distributions of dCo and dFe were observed. In the North Atlantic gyre provinces, extremely low mixed layer dCo concentrations (23 ± 9 pM) were observed, which contrasts with the relatively high mixed layer dFe concentrations (up to 1.0 nM) coincident with the band of highest atmospheric deposition (∼5-30°N). In the South Atlantic gyre, the opposite trend was observed, with relatively high dCo (55 ± 18 pM) observed throughout the water column, but low dFe concentrations (0.29 ± 0.08 nM). Given that annual dust supply is an order of magnitude greater in the North than the South Atlantic, the dCo distribution was somewhat unexpected. However, the distribution of dCo shows similarities with the distribution of phosphate (PO43-) in the euphotic zone of the Atlantic Ocean, where the North Atlantic gyre is characterised by chronically low PO4, and higher concentrations are observed in the South Atlantic gyre (Mather et al., 2008), suggesting the potential for a similar biological control of dCo distributions. Inverse correlations between dCo and Prochlorococcus abundance in the North Atlantic gyre provinces, combined with extremely low dCo where nitrogen fixation rates were highest (∼20-28°N), suggests the dominance of biological controls on dCo distributions. The contrasting dCo and dFe distributions in the North and South Atlantic gyres provides insights into the differences between the dominant controls on the

Factors influencing particulate lipid production in the East Atlantic Ocean

NASA Astrophysics Data System (ADS)

Gašparović, B.; Frka, S.; Koch, B. P.; Zhu, Z. Y.; Bracher, A.; Lechtenfeld, O. J.; Neogi, S. B.; Lara, R. J.; Kattner, G.

2014-07-01

Extensive analyses of particulate lipids and lipid classes were conducted to gain insight into lipid production and related factors along the biogeochemical provinces of the Eastern Atlantic Ocean. Data are supported by particulate organic carbon (POC), chlorophyll a (Chl a), phaeopigments, Chl a concentrations and carbon content of eukaryotic micro-, nano- and picophytoplankton, including cell abundances for the latter two and for cyanobacteria and prokaryotic heterotrophs. We focused on the productive ocean surface (2 m depth and deep Chl a maximum (DCM). Samples from the deep ocean provided information about the relative reactivity and preservation potential of particular lipid classes. Surface and DCM particulate lipid concentrations (3.5-29.4 μg L-1) were higher than in samples from deep waters (3.2-9.3 μg L-1) where an increased contribution to the POC pool was observed. The highest lipid concentrations were measured in high latitude temperate waters and in the North Atlantic Tropical Gyral Province (13-25°N). Factors responsible for the enhanced lipid synthesis in the eastern Atlantic appeared to be phytoplankton size (micro, nano, pico) and the low nutrient status with microphytoplankton having the most expressed influence in the surface and eukaryotic nano- and picophytoplankton in the DCM layer. Higher lipid to Chl a ratios suggest enhanced lipid biosynthesis in the nutrient poorer regions. The various lipid classes pointed to possible mechanisms of phytoplankton adaptation to the nutritional conditions. Thus, it is likely that adaptation comprises the replacement of membrane phospholipids by non-phosphorus containing glycolipids under low phosphorus conditions. The qualitative and quantitative lipid compositions revealed that phospholipids were the most degradable lipids, and their occurrence decreased with increasing depth. In contrast, wax esters, possibly originating from zooplankton, survived downward transport probably due to the fast sinking

Revisiting tropical instability wave variability in the Atlantic ocean using SODA reanalysis

NASA Astrophysics Data System (ADS)

de Decco, Hatsue Takanaca; Torres Junior, Audalio Rebelo; Pezzi, Luciano Ponzi; Landau, Luiz

2018-03-01

The spatial and temporal variability of energy exchange in Tropical Instability Waves (TIWs) in the Atlantic Ocean were investigated. A spectral analysis was used to filter the 5-day mean results from Simple Ocean Data Assimilation (SODA) reanalysis spanning from 1958 to 2008. TIWs were filtered over periods of 15 to 60 days and between wavelengths of 4 and 20 longitude degrees. The main approach of this study was the use of bidirectionally filtered TIW time series as the perturbation fields, and the difference in these time series from the SODA total results was considered to be the basic state for energetics analysis. The main result was that the annual cycle (period of 360 days) was the main source of variability of the waves, and the semi-annual cycle (period of 180 days) was a secondary variation, which indicated that TIWs occurred throughout the year but with intensity that varies seasonally. In SODA, barotropic instability acts as the mechanism that feeds and extracts energy to/from TIWs at equatorial Atlantic. Baroclinic instability is the main mechanism that extracts energy from TIWs to the equatorial circulation north of the Equator. All TIW patterns of variability were observed western of 10° W. The present study reveals new evidences regarding TIW variability and suggests that future investigations should include a detailed description of TIW dynamics as part of Atlantic Ocean equatorial circulation.

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

Organic matter in eolian dusts over the Atlantic Ocean

NASA Technical Reports Server (NTRS)

Simoneit, B. R. T.

1977-01-01

The elemental and mineralogical composition and the microfossil and detritus content of particulate fallout from the lower troposphere over the Atlantic Ocean have been extensively documented in earlier work, and it was possible to ascribe terrigenous source areas to such fallout. A brief review of the organic geochemistry of eolian dusts is also presented here. The lipids of eolian dusts sampled from the air mass over the eastern Atlantic from about 35 deg N to 30 deg S were analyzed here. These lipids consisted mainly of normal alkanes, carboxylic acids and alcohols. The n-alkanes were found to range from n-C23 to n-C35 with high CPI values and maximizing at n-C27 in the North Atlantic, at n-C29 in the equatorial Atlantic and at n-C31 in the South Atlantic. The n-fatty acids had mostly bimodal distributions, ranging from n-C12 to n-C30 (high CPI), with maxima at n-C16 and in the northern samples at n-C24 and in the southern samples at n-C26. The n-alcohols ranged from n-C12 to n-C32, with high CPI values and maxima mainly at n-C28. The compositions of these lipids indicated that their terrigenous sources were comprised mainly of higher plant vegetation and desiccated lacustrine mud flats on the African continent.

Vulnerability of teleosts caught by the pelagic tuna longline fleets in South Atlantic and Western Indian Oceans

NASA Astrophysics Data System (ADS)

Lucena-Frédou, Flávia; Kell, Laurie; Frédou, Thierry; Gaertner, Daniel; Potier, Michel; Bach, Pascal; Travassos, Paulo; Hazin, Fábio; Ménard, Frédéric

2017-06-01

Productivity and Susceptibility Analysis (PSA) is a methodology for evaluating the vulnerability of a stock based on its biological productivity and susceptibility to fishing. In this study, we evaluated the vulnerability of 60 stocks of tuna, billfishes and other teleosts caught by the tuna longline fleets operating in the South Atlantic and Indian Ocean using a semi-quantitative PSA. We (a) evaluated the vulnerability of the species in the study areas; (b) compared the vulnerability of target and non-target species and oceans; (c) analyzed the sensitivity of data entry; and (d) compared the results of the PSA to other fully quantitative assessment methods. Istiophoridae exhibited the highest scores for vulnerability. The top 10 species at risk were: Atlantic Istiophorus albicans; Indian Ocean Istiompax indica; Atlantic Makaira nigricans and Thunnus alalunga; Indian Ocean Xiphias gladius; Atlantic T. albacares, Gempylus serpens, Ranzania laevis and X. gladius; and Indian Ocean T. alalunga. All species considered at high risk were targeted or were commercialized bycatch, except for the Atlantic G. serpens and R. laevis which were discarded, and may be considered as a false positive. Those species and others at high risk should be prioritized for further assessment and/or data collection. Most species at moderate risk were bycatch species kept for sale. Conversely, species classified at low risk were mostly discarded. Overall, species at high risk were overfished and/or subjected to overfishing. Moreover, all species considered to be within extinction risk (Critically Endangered, Endangered and Vulnerable) were in the high-risk category. The good concordance between approaches corroborates the results of our analysis. PSA is not a replacement for traditional stock assessments, where a stock is assessed at regular intervals to provide management advice. It is of importance, however, where there is uncertainty about catches and life history parameters, since it can

Metabolism of Centropages species in the Mediterranean Sea and the North Atlantic Ocean

NASA Astrophysics Data System (ADS)

Gaudy, Raymond; Thibault-Botha, Delphine

2007-02-01

Information on the metabolism rates of Centropages typicus and congeneric species ( C. hamatus, C. furcatus, C. brachiatus and C. abdominalis) in neritic areas of the Mediterranean Sea, the North Atlantic Ocean and the Pacific Ocean are reported here. Respiration rates and excretion rates are strongly influenced by abiotic (i.e. temperature, salinity) and biotic factors (i.e. food availability and composition). Differences in the response of respiratory rates to temperature of acclimated, acclimatized and adapted individuals are clearly observed among regions of the Mediterranean Sea and the West and East shores of the Atlantic Ocean. Food supply also strongly affects respiration and excretion rates, as well as the size, sex and stage development of the individuals. The co-measurement of these two rates allows confirmation of the omnivory or carnivory oriented feeding habits of these species. The role of this neritic genus in coastal environment is also discussed.

Basin-scale variability in plankton biomass and community metabolism in the sub-tropical North Atlantic Ocean

NASA Astrophysics Data System (ADS)

Harrison, W. G.; Arístegui, J.; Head, E. J. H.; Li, W. K. W.; Longhurst, A. R.; Sameoto, D. D.

Three trans-Atlantic oceanographic surveys (Nova Scotia to Canary Islands) were carried out during fall 1992 and spring 1993 to describe the large-scale variability in hydrographic, chemical and biological properties of the upper water column of the subtropical gyre and adjacent waters. Significant spatial and temporal variability characterized a number of the biological pools and rate processes whereas others were relatively invariant. Systematic patterns were observed in the zonal distribution of some properties. Most notable were increases (eastward) in mixed-layer temperature and salinity, depths of the nitracline and chlorophyll- a maximum, regenerated production (NH 4 uptake) and bacterial production. Dissolved inorganic carbon (DIC) concentrations, phytoplankton biomass, mesozooplankton biomass and new production (NO 3 uptake) decreased (eastward). Bacterial biomass, primary production, and community respiration exhibited no discernible zonal distribution patterns. Seasonal variability was most evident in hydrography (cooler/fresher mixed-layer in spring), and chemistry (mixed-layer DIC concentration higher and nitracline shallower in spring) although primary production and bacterial production were significantly higher in spring than in fall. In general, seasonal variability was greater in the west than in the east; seasonality in most properties was absent west of Canary Islands (˜20°W). The distribution of autotrophs could be reasonably well explained by hydrography and nutrient structure, independent of location or season. Processes underlying the distribution of the microheterophs, however, were less clear. Heterotrophic biomass and metabolism was less variable than autotrophs and appeared to dominate the upper ocean carbon balance of the subtropical North Atlantic in both fall and spring. Geographical patterns in distribution are considered in the light of recent efforts to partition the ocean into distinct "biogeochemical provinces".

Dilution of the northern North Atlantic Ocean in recent decades.

PubMed

Curry, Ruth; Mauritzen, Cecilie

2005-06-17

Declining salinities signify that large amounts of fresh water have been added to the northern North Atlantic Ocean since the mid-1960s. We estimate that the Nordic Seas and Subpolar Basins were diluted by an extra 19,000 +/- 5000 cubic kilometers of freshwater input between 1965 and 1995. Fully half of that additional fresh water-about 10,000 cubic kilometers-infiltrated the system in the late 1960s at an approximate rate of 2000 cubic kilometers per year. Patterns of freshwater accumulation observed in the Nordic Seas suggest a century time scale to reach freshening thresholds critical to that portion of the Atlantic meridional overturning circulation.

Apollo 4 Mission - Atlantic Ocean,coastal Brazil and West Africa

NASA Image and Video Library

1967-11-09

AS04-01-200 (9 Nov. 1967) --- Coastal Brazil, Atlantic Ocean, West Africa, Sahara, looking northwest, as photographed from the unmanned Apollo 4 (Spacecraft 017/Saturn 501) earth-orbital space mission. This picture was taken when the Spacecraft 017 and the Saturn IVB stage were orbiting Earth at an altitude of 9,060 nautical miles.

Contrasting spatial structures of Atlantic Multidecadal Oscillation between observations and slab ocean model simulations

NASA Astrophysics Data System (ADS)

Sun, Cheng; Li, Jianping; Kucharski, Fred; Xue, Jiaqing; Li, Xiang

2018-04-01

The spatial structure of Atlantic multidecadal oscillation (AMO) is analyzed and compared between the observations and simulations from slab ocean models (SOMs) and fully coupled models. The observed sea surface temperature (SST) pattern of AMO is characterized by a basin-wide monopole structure, and there is a significantly high degree of spatial coherence of decadal SST variations across the entire North Atlantic basin. The observed SST anomalies share a common decadal-scale signal, corresponding to the basin-wide average (i. e., the AMO). In contrast, the simulated AMO in SOMs (AMOs) exhibits a tripole-like structure, with the mid-latitude North Atlantic SST showing an inverse relationship with other parts of the basin, and the SOMs fail to reproduce the observed strong spatial coherence of decadal SST variations associated with the AMO. The observed spatial coherence of AMO SST anomalies is identified as a key feature that can be used to distinguish the AMO mechanism. The tripole-like SST pattern of AMOs in SOMs can be largely explained by the atmosphere-forced thermodynamics mechanism due to the surface heat flux changes associated with the North Atlantic Oscillation (NAO). The thermodynamic forcing of AMOs by the NAO gives rise to a simultaneous inverse NAO-AMOs relationship at both interannual and decadal timescales and a seasonal phase locking of the AMOs variability to the cold season. However, the NAO-forced thermodynamics mechanism cannot explain the observed NAO-AMO relationship and the seasonal phase locking of observed AMO variability to the warm season. At decadal timescales, a strong lagged relationship between NAO and AMO is observed, with the NAO leading by up to two decades, while the simultaneous correlation of NAO with AMO is weak. This lagged relationship and the spatial coherence of AMO can be well understood from the view point of ocean dynamics. A time-integrated NAO index, which reflects the variations in Atlantic meridional overturning

33 CFR 334.1460 - Atlantic Ocean and Vieques Sound, in vicinity of Culebra Island; bombing and gunnery target area.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Commander, Caribbean Sea Frontier, San Juan, Puerto Rico, and such agencies as he may designate. (Sec. 7, 40... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false Atlantic Ocean and Vieques Sound... RESTRICTED AREA REGULATIONS § 334.1460 Atlantic Ocean and Vieques Sound, in vicinity of Culebra Island...

33 CFR 334.1460 - Atlantic Ocean and Vieques Sound, in vicinity of Culebra Island; bombing and gunnery target area.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Commander, Caribbean Sea Frontier, San Juan, Puerto Rico, and such agencies as he may designate. (Sec. 7, 40... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Atlantic Ocean and Vieques Sound... RESTRICTED AREA REGULATIONS § 334.1460 Atlantic Ocean and Vieques Sound, in vicinity of Culebra Island...

33 CFR 334.1460 - Atlantic Ocean and Vieques Sound, in vicinity of Culebra Island; bombing and gunnery target area.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Commander, Caribbean Sea Frontier, San Juan, Puerto Rico, and such agencies as he may designate. (Sec. 7, 40... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Atlantic Ocean and Vieques Sound... RESTRICTED AREA REGULATIONS § 334.1460 Atlantic Ocean and Vieques Sound, in vicinity of Culebra Island...

33 CFR 334.590 - Atlantic Ocean off Cape Canaveral, Fla.; Air Force missile testing area, Patrick Air Force Base...

Code of Federal Regulations, 2010 CFR

2010-07-01

..., Fla.; Air Force missile testing area, Patrick Air Force Base, Fla. 334.590 Section 334.590 Navigation... RESTRICTED AREA REGULATIONS § 334.590 Atlantic Ocean off Cape Canaveral, Fla.; Air Force missile testing area, Patrick Air Force Base, Fla. (a) The danger zone. An area in the Atlantic Ocean immediately offshore from...

Anomalous Structure of Oceanic Lithosphere in the North Atlantic and Arctic Oceans: A Preliminary Analysis Based on Bathymetry, Gravity and Crustal Structure

NASA Astrophysics Data System (ADS)

Barantsrva, O.

2014-12-01

We present a preliminary analysis of the crustal and upper mantle structure for off-shore regions in the North Atlantic and Arctic oceans. These regions have anomalous oceanic lithosphere: the upper mantle of the North Atlantic ocean is affected by the Iceland plume, while the Arctic ocean has some of the slowest spreading rates. Our specific goal is to constrain the density structure of the upper mantle in order to understand the links between the deep lithosphere dynamics, ocean spreading, ocean floor bathymetry, heat flow and structure of the oceanic lithosphere in the regions where classical models of evolution of the oceanic lithosphere may not be valid. The major focus is on the oceanic lithosphere, but the Arctic shelves with a sufficient data coverage are also included into the analysis. Out major interest is the density structure of the upper mantle, and the analysis is based on the interpretation of GOCE satellite gravity data. To separate gravity anomalies caused by subcrustal anomalous masses, the gravitational effect of water, crust and the deep mantle is removed from the observed gravity field. For bathymetry we use the global NOAA database ETOPO1. The crustal correction to gravity is based on two crustal models: (1) global model CRUST1.0 (Laske, 2013) and, for a comparison, (2) a regional seismic model EUNAseis (Artemieva and Thybo, 2013). The crustal density structure required for the crustal correction is constrained from Vp data. Previous studies have shown that a large range of density values corresponds to any Vp value. To overcome this problem and to reduce uncertainty associated with the velocity-density conversion, we account for regional tectonic variations in the Northern Atlantics as constrained by numerous published seismic profiles and potential-field models across the Norwegian off-shore crust (e.g. Breivik et al., 2005, 2007), and apply different Vp-density conversions for different parts of the region. We present preliminary results

Microplastic abundance, distribution and composition along a latitudinal gradient in the Atlantic Ocean.

PubMed

Kanhai, La Daana K; Officer, Rick; Lyashevska, Olga; Thompson, Richard C; O'Connor, Ian

2017-02-15

Microplastics in the world's oceans are a global concern due to the potential threat they pose to marine organisms. This study investigated microplastic abundance, distribution and composition in the Atlantic Ocean on a transect from the Bay of Biscay to Cape Town, South Africa. Microplastics were sampled from sub-surface waters using the underway system of the RV Polarstern. Potential microplastics were isolated from samples and FT-IR spectroscopy was used to identify polymer types. Of the particles analysed, 63% were rayon and 37% were synthetic polymers. The majority of microplastics were identified as polyesters (49%) and blends of polyamide or acrylic/polyester (43%). Overall, fibres (94%) were predominant. Average microplastic abundance in the Atlantic Ocean was 1.15±1.45particlesm -3 . Of the 76 samples, 14 were from the Benguela upwelling and there was no statistically significant difference in microplastic abundance between upwelled and non-upwelled sites. Copyright © 2016 Elsevier Ltd. All rights reserved.

Brazil, Atlantic Ocean, Africa, Sahara & Antarctica seen from Apollo 4

NASA Image and Video Library

1967-11-09

AS04-01-410 (9 Nov. 1967) --- Coastal Brazil, Atlantic Ocean, West Africa, Sahara, Antarctica, looking west, as photographed from the Apollo 4 (Spacecraft 017/Saturn 501) unmanned, Earth-orbital space mission. This picture was taken when the Spacecraft 017 and Saturn S-IVB (third) stage were orbiting Earth at an altitude of 9,745 nautical miles.

Phytoplankton bloom in the North Atlantic Ocean

NASA Image and Video Library

2017-12-08

On July 23, 2013 the deep blue waters of the central North Atlantic Ocean provided a background for a spectacular bloom of phytoplankton. The Moderate Resolution Imaging Spectroradiometer (MODIS) captured this true-color image of the event at 16:25 UTC (12:25 p.m. EDT) that same day. Phytoplankton are tiny single-celled photosynthetic organisms that live suspended in a watery environment. They are primary producers in the ocean, forming the base of the marine food chain, and, like terrestrial plants, take up carbon dioxide, make carbohydrates from energy from light, and release oxygen. Phytoplankton live in the ocean year round, but are usually not visible. When light, nutrients and water temperature are just right, however, a colony can explode into growth, creating huge blooms that stain the ocean for miles. While each organism lives only a short time, the high reproductive means that a bloom can last for days or weeks. Credit: NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Spatiotemporal evolution of the chlorophyll a trend in the North Atlantic Ocean.

PubMed

Zhang, Min; Zhang, Yuanling; Shu, Qi; Zhao, Chang; Wang, Gang; Wu, Zhaohua; Qiao, Fangli

2018-01-15

Analyses of the chlorophyll a concentration (chla) from satellite ocean color products have suggested the decadal-scale variability of chla linked to the climate change. The decadal-scale variability in chla is both spatially and temporally non-uniform. We need to understand the spatiotemporal evolution of chla in decadal or multi-decadal timescales to better evaluate its linkage to climate variability. Here, the spatiotemporal evolution of the chla trend in the North Atlantic Ocean for the period 1997-2016 is analyzed using the multidimensional ensemble empirical mode decomposition method. We find that this variable trend signal of chla shows a dipole pattern between the subpolar gyre and along the Gulf Stream path, and propagation along the opposite direction of the North Atlantic Current. This propagation signal has an overlapping variability of approximately twenty years. Our findings suggest that the spatiotemporal evolution of chla during the two most recent decades is part of the multidecadal variations and possibly regulated by the changes of Atlantic Meridional Overturning Circulation, whereas the mechanisms of such evolution patterns still need to be explored. Copyright © 2017 Elsevier B.V. All rights reserved.

Low-Temperature Thermochronology Of Rio Grande Rise, South Atlantic Ocean

NASA Astrophysics Data System (ADS)

Doranti Tiritan, Carolina; Hackspacher, Peter Christian; Carina Siqueira Ribeiro, Marli

2017-04-01

The Rio Grande Rise (RGR) is a submerse plateau 1500 km distant from Brazilian coast, on Ocidental South Atlantic Ocean. It is interpreted as a great igneous province connected in the past with the Walvis Ridge on the Oriental South Atlantic. First hypothesis about their genesis rely on the great magmatic activity associated with the Tristao Cunha-Gough plume. However, recently, more evidences suggest that the RGR is a fragment of continental crust that could have been separated from the São Paulo Plateau during the South Atlantic opening process. New seismic data and in situ observation have reinforced this interpretation, which has been created more significantly questioning about the from the continental break has occurred, as well on how was the role and genesis of the hot spots that were manifested through the plume. This work will be presenting thermochronological data from RGR rocks collected by Brazilian Geological Service (CPRM) and Bremen IODP repository. We intend to have more data that will allow to reconstruct the processes of subsidence and rock uplift that could have occurred during Cretaceous and Eocene. It will be possible calculate exhumation rates and correlate them or not to the formation of the oceanic crust, time as an island and if the velocity of the subsidence. This work is part of a major project called "Elevação do Alto Rio Grande, Atlantico Sul Ocidental", financed by IODP/CAPES.

33 CFR 207.160 - All waterways tributary to the Atlantic Ocean south of Chesapeake Bay and all waterways tributary...

Code of Federal Regulations, 2014 CFR

2014-07-01

... Atlantic Ocean south of Chesapeake Bay and all waterways tributary to the Gulf of Mexico east and south of... tributary to the Gulf of Mexico east and south of St. Marks, Fla.; use, administration, and navigation. (a... Atlantic Ocean south of Chesapeake Bay or with the Gulf of Mexico east and south of St. Marks, Florida. (2...

33 CFR 207.160 - All waterways tributary to the Atlantic Ocean south of Chesapeake Bay and all waterways tributary...

Code of Federal Regulations, 2013 CFR

2013-07-01

... Atlantic Ocean south of Chesapeake Bay and all waterways tributary to the Gulf of Mexico east and south of... tributary to the Gulf of Mexico east and south of St. Marks, Fla.; use, administration, and navigation. (a... Atlantic Ocean south of Chesapeake Bay or with the Gulf of Mexico east and south of St. Marks, Florida. (2...

33 CFR 207.160 - All waterways tributary to the Atlantic Ocean south of Chesapeake Bay and all waterways tributary...

Code of Federal Regulations, 2012 CFR

2012-07-01

... Atlantic Ocean south of Chesapeake Bay and all waterways tributary to the Gulf of Mexico east and south of... tributary to the Gulf of Mexico east and south of St. Marks, Fla.; use, administration, and navigation. (a... Atlantic Ocean south of Chesapeake Bay or with the Gulf of Mexico east and south of St. Marks, Florida. (2...

Calculation of wind-driven surface currents in the North Atlantic Ocean

NASA Technical Reports Server (NTRS)

Rees, T. H.; Turner, R. E.

1976-01-01

Calculations to simulate the wind driven near surface currents of the North Atlantic Ocean are described. The primitive equations were integrated on a finite difference grid with a horizontal resolution of 2.5 deg in longitude and latitude. The model ocean was homogeneous with a uniform depth of 100 m and with five levels in the vertical direction. A form of the rigid-lid approximation was applied. Generally, the computed surface current patterns agreed with observed currents. The development of a subsurface equatorial countercurrent was observed.

Mass, heat and nutrient fluxes in the Atlantic Ocean determined by inverse methods. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Rintoul, Stephen Rich

1988-01-01

Inverse methods are applied to historical hydrographic data to address two aspects of the general circulation of the Atlantic Ocean. The method allows conservation statements for mass and other properties, along with a variety of other constraints, to be combined in a dynamically consistent way to estimate the absolute velocity field and associated property transports. The method was first used to examine the exchange of mass and heat between the South Atlantic and the neighboring ocean basins. The second problem addressed concerns the circulation and property fluxes across the 24 and 36 deg N in the subtropical North Atlantic. Conservation statements are considered for the nutrients as well as mass, and the nutrients are found to contribute significant information independent of temperature and salinity.

Crustal structure of the Agulhas Ridge (South Atlantic Ocean): Formation above a hotspot?

NASA Astrophysics Data System (ADS)

Jokat, Wilfried; Hagen, Claudia

2017-10-01

The southern South Atlantic Ocean contains several features believed to document the traces of hotspot volcanism during the early formation of the ocean basin, namely the Agulhas Ridge and the Cape Rise seamounts located in the southeast Atlantic between 36°S and 50°S. The Agulhas Ridge parallels the Agulhas-Falkland Fracture Zone, one of the major transform zones of the world. The morphology of the ridge changes dramatically from two parallel segments in the southwest, to the broad plateau-like Agulhas Ridge in the northeast. Because the crustal fabric of the ridge is unknown relating its evolution to hotspots in the southeast Atlantic is an open question. During the RV Polarstern cruise ANT-XXIII-5 seismic reflection and refraction data were collected along a 370 km long profile with 8 Ocean Bottom Stations to investigate its crustal fabric. The profile extends in NNE direction from the Agulhas Basin, 60 km south of the Agulhas Ridge, and continues into the Cape Basin crossing the southernmost of the Cape Rise seamounts. In the Cape Basin we found a crustal thickness of 5.5-7.5 km, and a velocity distribution typical for oceanic crust. The Cape Rise seamounts, however, show a higher velocity in comparison to the surrounding oceanic crust and the Agulhas Ridge. Underplated material is evident below the southernmost of the Cape Rise seamounts. It also has a 5-8% higher density compared to the Agulhas Plateau. The seismic velocities of the Agulhas Ridge are lower, the crustal thickness is approximately 14 km, and age dating of dredge samples from its top provides clear evidence of rejuvenated volcanism at around 26 Ma. Seismic data indicate that although the Cape Rise seamounts formed above a mantle thermal anomaly it had a limited areal extent, whereas the hotspot material that formed the Agulhas Ridge likely erupted along a fracture zone.

Numerical Simulation of Salinity and Dissolved Oxygen at Perdido Bay and Adjacent Coastal Ocean

EPA Science Inventory

Environmental Fluid Dynamic Code (EFDC), a numerical estuarine and coastal ocean circulation hydrodynamic model, was used to simulate the distribution of the salinity, temperature, nutrients and dissolved oxygen (DO) in Perdido Bay and adjacent Gulf of Mexico. External forcing fa...

Glacial-Interglacial Variability of Nd isotopes in the South Atlantic and Southern Ocean

NASA Astrophysics Data System (ADS)

Knudson, K. P.; Goldstein, S. L.; Pena, L.; Seguí, M. J.; Kim, J.; Yehudai, M.; Fahey, T.

2017-12-01

Understanding the relationship between meridional overturning circulation and climate is key to understanding the processes and feedbacks underlying future climate changes. North Atlantic Deep Water (NADW) represents a major water mass that participates in global oceanic circulation and undergoes substantial reorganization with climate changes on millennial and orbital timescales. Nd isotopes are semi-quantitative water mass tracers that reflect the mixing of end-member water masses, and their values in the Southern Ocean offer the ability to characterize NADW variability over time. Here, we present paleo-circulation records of Nd isotopes measured on fish debris and Fe-Mn encrusted foraminifera from ODP Sites 1090 (42° 54.82'S, 3702 m), and 1094 (53° 10.81'S, 2807 m). Site 1090 is located in the Cape Basin, SE Atlantic, near the lower boundary between NADW and Circumpolar Deep Water (CDW), while 1094 is in the Circumpolar Current. They are ideal locations to monitor changes in the export of NADW to the Southern Ocean. These new results build on previous work (Pena and Goldstein, 2014) to document meridional overturning changes in the Southern Ocean.

Distribution and cycling of lead in the high and low latitudinal Atlantic Ocean

NASA Astrophysics Data System (ADS)

Schlosser, C.; Menzel Barraqueta, J. L.; Rapp, I.; Pampin Baro, J.; Achterberg, E. P.

2016-02-01

Lead (Pb) is a toxic trace metal; even small quantities are lethal to most unicellular and multicellular organisms. Major sources of lead to the environment are the burning of coal, industrial mining, and the use of leaded gasoline (which has not been entirely phased out of use around the globe). These and other anthropogenic sources of Pb continue to pollute the environment and affect primary production and the development of heterotrophic organisms in the sea. Pb concentrations in oceanic waters are ten to a hundred times higher in surface waters than in deep waters (0.05 - 0.1 nmol L-1 compared to 1 - 5 pmol L-1), this deposition-like profile clearly reflecting the significant anthropogenic input of Pb to the ocean. In order to explore the cycling and fate of this anthropogenic Pb, we collected seawater from the polar North Atlantic (JC274 in 2013, GEOVIDE in 2014), the sub-tropical Atlantic (D361 in 2011 & M107 in 2014), the South Atlantic (JC068 in 2012), and the Atlantic sector of the Southern Ocean (JC271 in 2013). These samples were analyzed for their dissolved and soluble and total dissolvable Pb concentrations by off-line pre-concentration using a SeaFAST device (Elemental Science Inc.) and isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS, Thermo ElementXR). Results indicate that dissolved Pb exists mainly as colloidal species, which, as the precursors of larger particles are subsequently critical for the removal of lead from the water column. For example, the removal of colloidal Pb through particle scavenging was observed in the high productivity waters of the Mauritanian upwelling region and at the outlet of the La Plata River on the South American shelf. In terms of Pb pollution, highest Pb concentrations (up to 60 pmol L-1) were observed in the Agulhas current. But even remote locations, such as the northern Arctic Ocean and near South Georgia in the Southern Ocean, activities of man had an impact; the Pb concentrations of 30

The distribution of lead concentrations and isotope compositions in the eastern Tropical Atlantic Ocean

NASA Astrophysics Data System (ADS)

Bridgestock, Luke; Rehkämper, Mark; van de Flierdt, Tina; Paul, Maxence; Milne, Angela; Lohan, Maeve C.; Achterberg, Eric P.

2018-03-01

Anthropogenic emissions have dominated marine Pb sources during the past century. Here we present Pb concentrations and isotope compositions for ocean depth profiles collected in the eastern Tropical Atlantic Ocean (GEOTRACES section GA06), to trace the transfer of anthropogenic Pb into the ocean interior. Variations in Pb concentration and isotope composition were associated with changes in hydrography. Water masses ventilated in the southern hemisphere generally featured lower 206Pb/207Pb and 208Pb/207Pb ratios than those ventilated in the northern hemisphere, in accordance with Pb isotope data of historic anthropogenic Pb emissions. The distributions of Pb concentrations and isotope compositions in northern sourced waters were consistent with differences in their ventilation timescales. For example, a Pb concentration maximum at intermediate depth (600-900 m, 35 pmol kg-1) in waters sourced from the Irminger/Labrador Seas, is associated with Pb isotope compositions (206Pb/207Pb = 1.1818-1.1824, 208Pb/207Pb = 2.4472-2.4483) indicative of northern hemispheric emissions during the 1950s and 1960s close to peak leaded petrol usage, and a transit time of ∼50-60 years. In contrast, North Atlantic Deep Water (2000-4000 m water depth) featured lower Pb concentrations and isotope compositions (206Pb/207Pb = 1.1762-1.184, 208Pb/207Pb = 2.4482-2.4545) indicative of northern hemispheric emissions during the 1910s and 1930s and a transit time of ∼80-100 years. This supports the notion that transient anthropogenic Pb inputs are predominantly transferred into the ocean interior by water mass transport. However, the interpretation of Pb concentration and isotope composition distributions in terms of ventilation timescales and pathways is complicated by (1) the chemical reactivity of Pb in the ocean, and (2) mixing of waters ventilated during different time periods. The complex effects of water mass mixing on Pb distributions is particularly apparent in seawater in the

Micro-phytoplankton photosynthesis, primary production and potential export production in the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Tilstone, Gavin H.; Lange, Priscila K.; Misra, Ankita; Brewin, Robert J. W.; Cain, Terry

2017-11-01

Micro-phytoplankton is the >20 μm component of the phytoplankton community and plays a major role in the global ocean carbon pump, through the sequestering of anthropogenic CO2 and export of organic carbon to the deep ocean. To evaluate the global impact of the marine carbon cycle, quantification of micro-phytoplankton primary production is paramount. In this paper we use both in situ data and a satellite model to estimate the contribution of micro-phytoplankton to total primary production (PP) in the Atlantic Ocean. From 1995 to 2013, 940 measurements of primary production were made at 258 sites on 23 Atlantic Meridional Transect Cruises from the United Kingdom to the South African or Patagonian Shelf. Micro-phytoplankton primary production was highest in the South Subtropical Convergence (SSTC ∼ 409 ± 720 mg C m-2 d-1), where it contributed between 38 % of the total PP, and was lowest in the North Atlantic Gyre province (NATL ∼ 37 ± 27 mg C m-2 d-1), where it represented 18 % of the total PP. Size-fractionated photosynthesis-irradiance (PE) parameters measured on AMT22 and 23 showed that micro-phytoplankton had the highest maximum photosynthetic rate (PmB) (∼5 mg C (mg Chl a)-1 h-1) followed by nano- (∼4 mg C (mg Chl a)-1 h-1) and pico- (∼2 mg C (mg Chl a)-1 h-1). The highest PmB was recorded in the NATL and lowest in the North Atlantic Drift Region (NADR) and South Atlantic Gyre (SATL). The PE parameters were used to parameterise a remote sensing model of size-fractionated PP, which explained 84 % of the micro-phytoplankton in situ PP variability with a regression slope close to 1. The model was applied to the SeaWiFS time series from 1998-2010, which illustrated that micro-phytoplankton PP remained constant in the NADR, NATL, Canary Current Coastal upwelling (CNRY), Eastern Tropical Atlantic (ETRA), Western Tropical Atlantic (WTRA) and SATL, but showed a gradual increase in the Benguela Upwelling zone (BENG) and South Subtropical Convergence (SSTC

Black Carbon in Estuarine and Coastal Ocean Dissolved Organic Matter

NASA Technical Reports Server (NTRS)

Mannino, Antonio; Harvey, H. Rodger

2003-01-01

Black carbon (BC) in ultrafiltered high-molecular-weight DOM (UDOM) was measured in surface waters of Delaware Bay, Chesapeake Bay and the adjacent Atlantic Ocean (USA) to ascertain the importance of riverine and estuarine DOM as a source of BC to the ocean. BC comprised 5-72% of UDOM-C (27+/-l7%) and on average 8.9+/-6.5% of dissolved organic carbon (DOC) with higher values in the turbid region of the Delaware Estuary and lower yields in the river and coastal ocean. The spatial and seasonal distributions of BC along the salinity gradient of Delaware Bay suggest that the higher levels of BC in surface water UDOM originated from localized sources, possibly from atmospheric deposition or released from resuspended sediments. Black carbon comprised 4 to 7% of the DOC in the coastal Atlantic Ocean, revealing that river-estuary systems are important exporters of colloidal BC to the ocean. The annual flux of BC from Delaware Bay UDOM to the Atlantic Ocean was estimated at 2.4x10(exp 10) g BC yr(exp -1). The global river flux of BC through DOM to the ocean could be on the order of 5.5x1O(exp 12)g BC yr (exp -1). These results support the hypothesis that the DOC pool is the intermediate reservoir in which BC ages prior to sedimentary deposition.

Transport of North Pacific 137Cs labeled waters to the south-eastern Atlantic Ocean

NASA Astrophysics Data System (ADS)

Sanchez-Cabeza, J. A.; Levy, I.; Gastaud, J.; Eriksson, M.; Osvath, I.; Aoyama, M.; Povinec, P. P.; Komura, K.

2011-04-01

During the reoccupation of the WOCE transect A10 at 30°S by the BEAGLE2003 cruise, the SHOTS project partners collected a large number of samples for the analysis of isotopic tracers. 137Cs was mostly deposited on the oceans surface during the late 1950s and early 1960s, after the atmospheric detonation of large nuclear devices, which mostly occurred in the Northern Hemisphere. The development of advanced radioanalytical and counting techniques allowed to obtain, for the first time in this region, a zonal section of 137Cs water concentrations, where little information existed before, thus constituting an important benchmark for further studies. 137Cs concentrations in the upper waters (0-1000 m) of the south-eastern Atlantic Ocean are similar to those observed in the south-western Indian Ocean, suggesting transport of 137Cs labeled waters by the Agulhas current to the Benguela Current region. In contrast, bomb radiocarbon data do not show this feature, indicating the usefulness of 137Cs as a radiotracer of water mass transport from the Indian to the South Atlantic Ocean.

Conservation Hotspots for the Turtles on the High Seas of the Atlantic Ocean

PubMed Central

Huang, Hsiang-Wen

2015-01-01

Understanding the distribution of bycaught sea turtles could inform conservation strategies and priorities. This research analyses the distribution of turtles caught as longline fisheries bycatch on the high seas of the Atlantic Ocean. This research collected 18,142 bycatch observations and 47.1 million hooks from large-scale Taiwanese longline vessels in the Atlantic Ocean from June 2002 to December 2013. The coverage rates were ranged from 0.48% to 17.54% by year. Seven hundred and sixty-seven turtles were caught, and the major species were leatherback (59.8%), olive ridley (27.1%) and loggerhead turtles (8.7%). Most olive ridley (81.7%) and loggerhead (82.1%) turtles were hooked, while the leatherbacks were both hooked (44.0%) and entangled (31.8%). Depending on the species, 21.4% to 57.7% were dead when brought onboard. Most of the turtles were caught in tropical areas, especially in the Gulf of Guinea (15°N-10°S, 30°W-10°E), but loggerheads were caught in the south Atlantic Ocean (25°S-35°S, 40°W-10°E and 30°S-40°S, 55°W-45°W). The bycatch rate was the highest at 0.030 per 1000 hooks for leatherbacks in the tropical area. The bycatch rates of olive ridley ranged from 0 to 0.010 per thousand hooks. The loggerhead bycatch rates were higher in the northern and southern Atlantic Ocean and ranged from 0.0128 to 0.0239 per thousand hooks. Due to the characteristics of the Taiwanese deep-set longline fleet, bycatch rates were lower than those of coastal longline fisheries, but mortality rates were higher because of the long hours of operation. Gear and bait modification should be considered to reduce sea turtle bycatch and increase survival rates while reducing the use of shallow hooks would also be helpful. PMID:26267796

Conservation hotspots for the turtles on the high seas of the Atlantic Ocean.

PubMed

Huang, Hsiang-Wen

2015-01-01

Understanding the distribution of bycaught sea turtles could inform conservation strategies and priorities. This research analyses the distribution of turtles caught as longline fisheries bycatch on the high seas of the Atlantic Ocean. This research collected 18,142 bycatch observations and 47.1 million hooks from large-scale Taiwanese longline vessels in the Atlantic Ocean from June 2002 to December 2013. The coverage rates were ranged from 0.48% to 17.54% by year. Seven hundred and sixty-seven turtles were caught, and the major species were leatherback (59.8%), olive ridley (27.1%) and loggerhead turtles (8.7%). Most olive ridley (81.7%) and loggerhead (82.1%) turtles were hooked, while the leatherbacks were both hooked (44.0%) and entangled (31.8%). Depending on the species, 21.4% to 57.7% were dead when brought onboard. Most of the turtles were caught in tropical areas, especially in the Gulf of Guinea (15°N-10°S, 30°W-10°E), but loggerheads were caught in the south Atlantic Ocean (25°S-35°S, 40°W-10°E and 30°S-40°S, 55°W-45°W). The bycatch rate was the highest at 0.030 per 1000 hooks for leatherbacks in the tropical area. The bycatch rates of olive ridley ranged from 0 to 0.010 per thousand hooks. The loggerhead bycatch rates were higher in the northern and southern Atlantic Ocean and ranged from 0.0128 to 0.0239 per thousand hooks. Due to the characteristics of the Taiwanese deep-set longline fleet, bycatch rates were lower than those of coastal longline fisheries, but mortality rates were higher because of the long hours of operation. Gear and bait modification should be considered to reduce sea turtle bycatch and increase survival rates while reducing the use of shallow hooks would also be helpful.

Biogeochemistry of dissolved arsenic in the temperate to tropical North Atlantic Ocean

NASA Astrophysics Data System (ADS)

Wurl, Oliver; Shelley, Rachel U.; Landing, William M.; Cutter, Gregory A.

2015-06-01

The biogeochemical cycle of arsenic was examined in the water column across the North Atlantic from 39° to 17°N as part of the US GEOTRACES North Atlantic study (GEOTRACES Section GA03). Results show limited nutrient-like distribution of As5+, and upper ocean maxima in As3+ and methylated As as found in many other studies In the oligotrophic water masses, microbial communities, i.e. phytoplankton, appear to favor the reduction to As3+ instead of methylation as detoxification of As5+ taken up during phosphorus (P) limitation due to their chemical similarities. The depth-integrated average concentrations in the mixed layer depth of As3+ in the western and eastern Atlantic Ocean were 1.30±1.14 nmol L-1 (n=4) and 0.65 (n=2), respectively, and rose to 3.30 nmol L-1 (n=2) in the Central Atlantic Ocean. No pattern was observed for As5+ (15.7±2.8 nmol L-1, n=8) and methylated species were detected occasionally below 0.41 nmol L-1 in the mixed layer. Based on significant correlations between phosphate, alkaline phosphate activity (APA), a conventional proxy for P limitation, and As3+, we conclude that As3+ is a good proxy for P limitation within the upper water column similar to our earlier evaluation of surface data. Mass balances for the mixed layer show that atmospheric inputs of As5+ can compensate for the losses via export fluxes and microbial reduction to As3+. The cycling of As3+ is more complex, with sources from As5+ reduction and losses due to photochemical and microbial-induced oxidation. The resulting residence time of As3+ with respect to these processes can be as short as 0.7-3 days. Unlike As5+, atmospheric inputs of As3+ cannot balance the oxidative losses and the short residence time further limits horizontal and vertical advective/diffusive inputs. It appears that reduction of As5+ coupled with detoxification and general microbial reduction are the sources of As3+ in the oceanic mixed layer. While As3+ production during As5+ detoxification has been

Measurement of aerosol optical depth in the Atlantic Ocean and Mediterranean Sea

NASA Astrophysics Data System (ADS)

Smirnov, Alexander; Yershov, Oleg; Villevalde, Yuri

1995-12-01

A brief summary of aerosol optical depth measurements in a maritime atmosphere during the last three decades is presented. The results of more than fifty publications have been analyzed and are summarized in a single table. New results of spectral aerosol optical depth measurements (from 440 to 1030 nm) in the Mediterranean Sea and Atlantic Ocean made from aboard a research vessel are also presented. Comparison of aerosol optical depths obtained over the Mediterranean Sea in the winter 1989-1990 with other Mediterranean data indicate substantial seasonal difference. The angstrom parameter values for the central and western Atlantic indicate good agreement with the results obtained for the north Atlantic. The measurements in the subtropical Atlantic region show significant variations. The pure atmosphere in the winter 1989-1990 evolved in the fall of 1991 into very turbid conditions which were probably associated with Saharan dust.

33 CFR 334.1450 - Atlantic Ocean off north coast of Puerto Rico; practice firing areas, U.S. Army Forces Antilles.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false Atlantic Ocean off north coast of Puerto Rico; practice firing areas, U.S. Army Forces Antilles. 334.1450 Section 334.1450 Navigation and... RESTRICTED AREA REGULATIONS § 334.1450 Atlantic Ocean off north coast of Puerto Rico; practice firing areas...

33 CFR 334.1450 - Atlantic Ocean off north coast of Puerto Rico; practice firing areas, U.S. Army Forces Antilles.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false Atlantic Ocean off north coast of Puerto Rico; practice firing areas, U.S. Army Forces Antilles. 334.1450 Section 334.1450 Navigation and... RESTRICTED AREA REGULATIONS § 334.1450 Atlantic Ocean off north coast of Puerto Rico; practice firing areas...

33 CFR 334.1450 - Atlantic Ocean off north coast of Puerto Rico; practice firing areas, U.S. Army Forces Antilles.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false Atlantic Ocean off north coast of Puerto Rico; practice firing areas, U.S. Army Forces Antilles. 334.1450 Section 334.1450 Navigation and... RESTRICTED AREA REGULATIONS § 334.1450 Atlantic Ocean off north coast of Puerto Rico; practice firing areas...

33 CFR 334.1450 - Atlantic Ocean off north coast of Puerto Rico; practice firing areas, U.S. Army Forces Antilles.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false Atlantic Ocean off north coast of Puerto Rico; practice firing areas, U.S. Army Forces Antilles. 334.1450 Section 334.1450 Navigation and... RESTRICTED AREA REGULATIONS § 334.1450 Atlantic Ocean off north coast of Puerto Rico; practice firing areas...

Diversity and distribution of hyperiid amphipods along a latitudinal transect in the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Burridge, Alice K.; Tump, Marloes; Vonk, Ronald; Goetze, Erica; Peijnenburg, Katja T. C. A.

2017-11-01

As commensals and parasitoids of gelatinous plankton, hyperiid amphipods play unique and important ecological roles in pelagic food webs. Because the diversity and biogeography of this group in oceanic waters is poorly known, we examined diversity and distribution patterns of hyperiids along a basin-scale meridional transect in the Atlantic Ocean (Atlantic Meridional Transect cruise 22). Hyperiids were collected from epipelagic and upper mesopelagic depths at 27 stations between 39°N and 45°S. A total of 70 species in 36 genera and 17 families were identified, the majority of which belonged to the epipelagic Physocephalata infraorder. We observed maximum species and genus richness in the equatorial upwelling region (up to 35 species, 27 genera per station; 7°N-8°S), which appeared largely driven by increased diversity in the superfamily Platysceloidea, as well as a significant and positive relationship between species richness and sea surface temperature. Cluster analyses of hyperiid species assemblages along the transect broadly supported a division into gyral, equatorial, transitional, and subantarctic assemblages, congruent with Longhurst's biogeochemical provinces. Steepest transitions in hyperiid species composition occurred at the southern subtropical convergence zone (34-38°S). The majority of zooplankton groups show maximal diversity in subtropical waters, and our observations of equatorial maxima in species and genus richness for hyperiids suggest that the mechanisms controlling diversity in this group are distinct from other zooplanktonic taxa. These patterns may be driven by the distribution and diversity of gelatinous hosts for hyperiids, which remain poorly characterized at ocean basin scales. The data reported here provide new distributional records for epipelagic and upper mesopelagic hyperiids across six major oceanic provinces in the Atlantic Ocean.

Mercury in the atmosphere, snow and melt water ponds in the North Atlantic Ocean during Arctic summer.

PubMed

Aspmo, Katrine; Temme, Christian; Berg, Torunn; Ferrari, Christophe; Gauchard, L Pierre-Alexis; Fain, Xavier; Wibetoe, Grethe

2006-07-01

Atmospheric mercury speciation measurements were performed during a 10 week Arctic summer expedition in the North Atlantic Ocean onboard the German research vessel RV Polarstern between June 15 and August 29, 2004. This expedition covered large areas of the North Atlantic and Arctic Oceans between latitudes 54 degrees N and 85 degrees N and longitudes 16 degrees W and 16 degrees E. Gaseous elemental mercury (GEM), reactive gaseous mercury (RGM) and mercury associated with particles (Hg-P) were measured during this study. In addition, total mercury in surface snow and meltwater ponds located on sea ice floes was measured. GEM showed a homogeneous distribution over the open North Atlantic Ocean (median 1.53 +/- 0.12 ng/m3), which is in contrast to the higher concentrations of GEM observed over sea ice (median 1.82 +/- 0.24 ng/m3). It is hypothesized that this results from either (re-) emission of mercury contained in snow and ice surfaces that was previously deposited during atmospheric mercury depletion events (AMDE) in the spring or evasion from the ocean due to increased reduction potential at high latitudes during Arctic summer. Measured concentrations of total mercury in surface snow and meltwater ponds were low (all samples <10 ng/L), indicating that marginal accumulation of mercury occurs in these environmental compartments. Results also reveal low concentrations of RGM and Hg-P without a significant diurnal variability. These results indicate that the production and deposition of these reactive mercury species do not significantly contribute to the atmospheric mercury cycle in the North Atlantic Ocean during the Arctic summer.

Vigorous exchange between the Indian and Atlantic oceans at the end of the past five glacial periods.

PubMed

Peeters, Frank J C; Acheson, Ruth; Brummer, Geert-Jan A; De Ruijter, Wilhelmus P M; Schneider, Ralph R; Ganssen, Gerald M; Ufkes, Els; Kroon, Dick

2004-08-05

The magnitude of heat and salt transfer between the Indian and Atlantic oceans through 'Agulhas leakage' is considered important for balancing the global thermohaline circulation. Increases or reductions of this leakage lead to strengthening or weakening of the Atlantic meridional overturning and associated variation of North Atlantic Deep Water formation. Here we show that modern Agulhas waters, which migrate into the south Atlantic Ocean in the form of an Agulhas ring, contain a characteristic assemblage of planktic foraminifera. We use this assemblage as a modern analogue to investigate the Agulhas leakage history over the past 550,000 years from a sediment record in the Cape basin. Our reconstruction indicates that Indian-Atlantic water exchange was highly variable: enhanced during present and past interglacials and largely reduced during glacial intervals. Coherent variability of Agulhas leakage with northern summer insolation suggests a teleconnection to the monsoon system. The onset of increased Agulhas leakage during late glacial conditions took place when glacial ice volume was maximal, suggesting a crucial role for Agulhas leakage in glacial terminations, timing of interhemispheric climate change and the resulting resumption of the Atlantic meridional overturning circulation.

Contributions of the atmosphere-land and ocean-sea ice model components to the tropical Atlantic SST bias in CESM1

NASA Astrophysics Data System (ADS)

Song, Z.; Lee, S. K.; Wang, C.; Kirtman, B. P.; Qiao, F.

2016-02-01

In order to identify and quantify intrinsic errors in the atmosphere-land and ocean-sea ice model components of the Community Earth System Model version 1 (CESM1) and their contributions to the tropical Atlantic sea surface temperature (SST) bias in CESM1, we propose a new method of diagnosis and apply it to a set of CESM1 simulations. Our analyses of the model simulations indicate that both the atmosphere-land and ocean-sea ice model components of CESM1 contain large errors in the tropical Atlantic. When the two model components are fully coupled, the intrinsic errors in the two components emerge quickly within a year with strong seasonality in their growth rates. In particular, the ocean-sea ice model contributes significantly in forcing the eastern equatorial Atlantic warm SST bias in early boreal summer. Further analysis shows that the upper thermocline water underneath the eastern equatorial Atlantic surface mixed layer is too warm in a stand-alone ocean-sea ice simulation of CESM1 forced with observed surface flux fields, suggesting that the mixed layer cooling associated with the entrainment of upper thermocline water is too weak in early boreal summer. Therefore, although we acknowledge the potential importance of the westerly wind bias in the western equatorial Atlantic and the low-level stratus cloud bias in the southeastern tropical Atlantic, both of which originate from the atmosphere-land model, we emphasize here that solving those problems in the atmosphere-land model alone does not resolve the equatorial Atlantic warm bias in CESM1.

Predicting plankton net community production in the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Serret, Pablo; Robinson, Carol; Fernández, Emilio; Teira, Eva; Tilstone, Gavin; Pérez, Valesca

2009-07-01

We present, test and implement two contrasting models to predict euphotic zone net community production (NCP), which are based on 14C primary production (PO 14CP) to NCP relationships over two latitudinal (ca. 30°S-45°N) transects traversing highly productive and oligotrophic provinces of the Atlantic Ocean (NADR, CNRY, BENG, NAST-E, ETRA and SATL, Longhurst et al., 1995 [An estimation of global primary production in the ocean from satellite radiometer data. Journal of Plankton Research 17, 1245-1271]). The two models include similar ranges of PO 14CP and community structure, but differ in the relative influence of allochthonous organic matter in the oligotrophic provinces. Both models were used to predict NCP from PO 14CP measurements obtained during 11 local and three seasonal studies in the Atlantic, Pacific and Indian Oceans, and from satellite-derived estimates of PO 14CP. Comparison of these NCP predictions with concurrent in situ measurements and geochemical estimates of NCP showed that geographic and annual patterns of NCP can only be predicted when the relative trophic importance of local vs. distant processes is similar in both modeled and predicted ecosystems. The system-dependent ability of our models to predict NCP seasonality suggests that trophic-level dynamics are stronger than differences in hydrodynamic regime, taxonomic composition and phytoplankton growth. The regional differences in the predictive power of both models confirm the existence of biogeographic differences in the scale of trophic dynamics, which impede the use of a single generalized equation to estimate global marine plankton NCP. This paper shows the potential of a systematic empirical approach to predict plankton NCP from local and satellite-derived P estimates.

Baroclinic stabilization effect of the Atlantic-Arctic water exchange simulated by the eddy-permitting ocean model and global atmosphere-ocean model

NASA Astrophysics Data System (ADS)

Moshonkin, Sergey; Bagno, Alexey; Gritsun, Andrey; Gusev, Anatoly

2017-04-01

Numerical experiments were performed with the global atmosphere-ocean model INMCM5 (for version of the international project CMIP6, resolution for atmosphere is 2°x1.5°, 21 level) and with the three-dimensional, free surface, sigma coordinate eddy-permitting ocean circulation model for Atlantic (from 30°S) - Arctic and Bering sea domain (0.25 degrees resolution, Institute of Numerical Mathematics Ocean Model or INMOM). Spatial resolution of the INMCM5 oceanic component is 0.5°x0.25°. Both models have 40 s-levels in ocean. Previously, the simulations were carried out for INMCM5 to generate climatic system stable state. Then model was run for 180 years. In the experiment with INMOM, CORE-II data for 1948-2009 were used. As the goal for comparing results of two these numerical models, we selected evolution of the density and velocity anomalies in the 0-300m active ocean layer near Fram Strait in the Greenland Sea, where oceanic cyclonic circulation influences Atlantic-Arctic water exchange. Anomalies were count without climatic seasonal cycle for time scales smaller than 30 years. We use Singular Value Decomposition analysis (SVD) for density-velocity anomalies with time lag from minus one to six months. Both models perform identical stable physical result. They reveal that changes of heat and salt transports by West Spitsbergen and East Greenland currents, caused by atmospheric forcing, produce the baroclinic modes of velocity anomalies in 0-300m layer, thereby stabilizing ocean response on the atmospheric forcing, which stimulates keeping water exchange between the North Atlantic and Arctic Ocean at the certain climatological level. The first SVD-mode of density-velocity anomalies is responsible for the cyclonic circulation variability. The second and third SVD-modes stabilize existing ocean circulation by the anticyclonic vorticity generation. The second and third SVD-modes give 35% of the input to the total dispersion of density anomalies and 16-18% of the

Correspondence between North Pacific Ocean ventilation, Cordilleran Ice Sheet variations, and North Atlantic Heinrich Events

NASA Astrophysics Data System (ADS)

Walczak, M. H.; Mix, A.; Fallon, S.; Praetorius, S. K.; Cowan, E. A.; Du, J.; Hobern, T.; Padman, J.; Fifield, L. K.; Stoner, J. S.; Haley, B. A.

2017-12-01

Much remains unresolved concerning the origin and global implications of the episodes of rapid glacial failure in the North Atlantic known as Heinrich Events. Thought to occur during or at the termination of the coldest of the abrupt stadial climate events known as Dansgaard-Oschger cycles, various trigger mechanisms have been theorized, including external forcing in the form of oceanic or atmospheric warming, internal dynamics of the large Laurentide ice sheet, or the episodic failure of another (presumably European) ice sheet. Heinrich events may also be associated with a decrease in North Atlantic deep-water formation. New results from Gulf of Alaska IODP Expedition 341 reveal events of Cordilleran Ice Sheet retreat (based on ice-rafted detritus and sedimentation rates) synchronous with reorganization of ocean circulation (based on benthic-planktic 14C pairs) spanning the past 45,000 years on an independent high-resolution radiocarbon-based chronology. We document the relationship between these Pacific records and the North Atlantic Heinrich events, and find the data show an early Pacific expression of ice sheet instability in the form of pulses of Cordilleran glacial discharge. The benthic radiocarbon anomalies in the Northeast Pacific contemporaneous with Cordilleran discharge events indicate a close coupling of ice-ocean dynamics throughout Marine Isotope Stage 2. These data are hard to reconcile with triggering in the North Atlantic or internal to the Laurentide ice sheet, requiring us to re-think both the mechanisms that generate Heinrich events and their far-field impacts.

Deglacial Ocean Circulation Scheme at Intermediate Depths in the Tropical North Atlantic

NASA Astrophysics Data System (ADS)

Xie, R. C.; Marcantonio, F.; Schmidt, M. W.

2014-12-01

In the modern Atlantic Ocean, intermediate water circulation is largely governed by the southward flowing upper North Atlantic Deep Water (NADW) and the northward return flow Antarctic Intermediate Water (AAIW). During the last deglaciation, it is commonly accepted that the southward flow Glacial North Atlantic Intermediate Water, the glacial analogue of NADW, contributed significantly to past variations in intermediate water circulation. However, to date, there is no common consensus of the role AAIW played during the last deglaciation, especially across abrupt climate events such as the Heinrich 1 and the Younger Dryas. This study aims to reconstruct intermediate northern- and southern-sourced water circulation in the tropical North Atlantic during the past 22 kyr and attempts to confine the boundary between AAIW and northern-sourced intermediate waters in the past. High-resolution Nd isotopic compositions (ɛNd thereafter) of fish debris and bulk sediment acid-reductive leachate from the Southern Caribbean (VM12-107; 1079 m) are inconsistent, again casting concerns, as already raised by recent studies, on the reliability of the leachate method in extracting seawater ɛNd signature. This urges the need to carefully verify the seawater ɛNd integrity in sediment acid-reductive leachate in various oceanic settings. Fish debris Nd isotope record in our study displays a two-step decreasing trend from the early deglaciation to early Holocene. We interpret this as recording a two-step deglacial recovery of the upper NADW, given the assumption on a more radiogenic glacial northern-sourced water is valid. Comparing with authigenic ɛNd records in the Florida Straits [1] and the Demarara Rise [2], our new fish debris ɛNd results suggest that, in the tropical western North Atlantic, glacial and deglacial AAIW never penetrated beyond the lower depth limit of modern AAIW. [1] Xie et al., GCA (140) 2014; [2] Huang et al., EPSL (389) 2014

Nature Run for the North Atlantic Ocean Hurricane Region: System Evaluation and Regional Applications

NASA Astrophysics Data System (ADS)

Kourafalou, V.; Androulidakis, I.; Halliwell, G. R., Jr.; Kang, H.; Mehari, M. F.; Atlas, R. M.

2016-02-01

A prototype ocean Observing System Simulation Experiments (OSSE) system, first developed and data validated in the Gulf of Mexico, has been applied on the extended North Atlantic Ocean hurricane region. The main objectives of this study are: a) to contribute toward a fully relocatable ocean OSSE system by expanding the Gulf of Mexico OSSE to the North Atlantic Ocean; b) demonstrate and quantify improvements in hurricane forecasting when the ocean component of coupled hurricane models is advanced through targeted observations and assimilation. The system is based on the Hybrid Coordinate Ocean Model (HYCOM) and has been applied on a 1/250 Mercator mesh for the free-running Nature Run (NR) and on a 1/120 Mercator mesh for the data assimilative forecast model (FM). A "fraternal twin" system is employed, using two different realizations for NR and FM, each configured to produce substantially different physics and truncation errors. The NR has been evaluated using a variety of available observations, such as from AVISO, GDEM climatology and GHRSST observations, plus specific regional products (upper ocean profiles from air-borne instruments, surface velocity maps derived from the historical drifter data set and tropical cyclone heat potential maps derived from altimetry observations). The utility of the OSSE system to advance the knowledge of regional air-sea interaction processes related to hurricane activity is demonstrated in the Amazon region (salinity induced surface barrier layer) and the Gulf Stream region (hurricane impact on the Gulf Stream extension).

Gene flow between Atlantic and Pacific Ocean basins in three lineages of deep-sea clams (Bivalvia: Vesicomyidae: Pliocardiinae) and subsequent limited gene flow within the Atlantic

NASA Astrophysics Data System (ADS)

LaBella, Abigail Leavitt; Van Dover, Cindy L.; Jollivet, Didier; Cunningham, Clifford W.

2017-03-01

Pliocardiin (vesicomyid) clams rely on microbial symbionts for nutrition and are obligate inhabitants of deep-sea chemosynthetic ecosystems. Unlike many other invertebrate hosts of chemosynthetic microbes, pliocardiin clams are found in every ocean in a variety of reducing habitats, including hydrothermal vents, cold seeps, organic falls and deep-sea fans. The global distribution of pliocardiin clams suggests historical gene flow between ocean basins. We focus on 3 pliocardiin genera-'Pliocardia' I, Calyptogena and Abyssogena-each of which has a pair of sister clades in the Atlantic and Pacific. Our work tests the hypothesis that historical gene flow between the Atlantic and Pacific Oceans within these genera was interrupted by the closure of the Panamanian seaway and tests whether isolation between the ocean basins is the result of vicariance or past colonization. These questions are investigated in the context of fossil evidence, biogeography and phylogenetics. This study revealed a set of substitution rates consistent with other invertebrate studies (μ=0.8%/My/lineage), and a set consistent with much lower rates often attributed to deep-sea organisms (μ=0.3%/My/lineage). Among the Pacific/Atlantic sister pairs, 'Pliocardia' I COI divergence per lineage is intermediate (2.5%), Calyptogena is the highest (6.1%) and Abyssogena the lowest (0.8%). The substitution rates suggest that 'Pliocardia' I and Calyptogena have histories of at least 2.8 My in the Atlantic, with Calyptogena likely older. The slower rate, however, is inconsistent with both the maximum age of the family and several well studied fossils: leaving the faster rate preferred. With the faster rate, the Abyssogena southwardae clade diverged from its Pacific sister clade around 1 Mya, which likely post-dates the closure of the Isthmus of Panama and the opening of the Bering Strait. In light of this recent divergence, we test the previously proposed hypothesis that there is a high level of ongoing gene

The Atlantic Ocean: An Impassable Barrier for the Common Octopus, Octopus vulgaris

NASA Astrophysics Data System (ADS)

Perez-Viscasillas, J.; Schizas, N. V.; Jassoud, A.

2016-02-01

Octopus vulgaris (Lamarck 1798) inhabits the Mediterranean, the temperate and tropical coastal waters of the Atlantic Ocean and is also present in the south Indian Ocean and Japan. We questioned the reported widespread distribution and especially the amphi-Atlantic distribution of O. vulgaris by comparing patterns of genetic variation in the Cytochrome Oxidase Subunit I (COI), the 17th intron of the Na(+)/K(+)-ATPase alpha subunit (Na/K-ATPase 17th intron), and 16S genes from several populations throughout the presumed distribution. Bayesian genealogies based on COI sequences resulted in three monophyletic lineages: a Caribbean, a Eurafrican and a Japanese one. The Eurafrican lineage is more closely related to the Japanese than to the Caribbean lineage. Within the Caribbean, the most common mitochondrial haplotype is shared by all sampled locations except for Curaçao. The most common COI haplotype in the Eurafrican group is shared by all populations. The Caribbean octopus exhibits a divergence of 11.5% compared to the Eurafrican and Japanese octopus, whereas the latter groups are 3.1% divergent. The Na/K-ATPase 17th intron data from Caribbean and Mediterranean/Atlantic Spain octopods is concordant with the mitochondrial data set, separating these two populations. The 16s data is still being analysed, but preliminary analysis supports the dual population hypothesis. The reciprocal monophyly observed with both COI and Na/K-ATPase 17th intron between the Caribbean and European O. vulgaris suggests the historical cessation of gene flow between the two sides of the Atlantic and highlights the presence of a highly differentiated Caribbean lineage.

Variability of the Tropical Ocean Surface Temperatures at Decadal-Multidecadal Timescales. Part I: The Atlantic Ocean.

NASA Astrophysics Data System (ADS)

Mehta, Vikram M.

1998-09-01

Gridded time series from the Global Ocean Surface Temperature Atlas were analyzed with a variety of techniques to identify spatial structures and oscillation periods of the tropical Atlantic sea surface temperature (SST) variations at decadal timescales, and to develop physical interpretations of statistical patterns of decadal SST variations. Each time series was 110 yr (1882-1991) long. The tropical Atlantic SST variations were compared with decadal variations in a 74-yr-long (1912-85) north Nordeste Brazil rainfall time series and a 106-yr-long (1886-1991) tropical Atlantic cyclone activity index time series. The tropical Atlantic SST variations were also compared with decadal variations in the extratropical Atlantic SST.Multiyear to multidecadal variations in the cross-equatorial dipole pattern identified as a dominant empirical pattern of the tropical Atlantic SST variations in earlier and present studies are shown to be variations in the approximately north-south gradient of SST anomalies. It is also shown that there was no dynamical-thermodynamical, dipole mode of SST variations during the analysis period. There was a distinct decadal timescale (12-13 yr) of SST variations in the tropical South Atlantic, whereas no distinct decadal timescale was found in the tropical North Atlantic SST variations. Approximately 80% of the coherent decadal variance in the cross-equatorial SST gradient was `explained' by coherent decadal oscillations in the tropical South Atlantic SSTs. There were three, possibly physical, modes of decadal variations in the tropical Atlantic SSTs during the analysis period. In the more energetic mode of the North Atlantic decadal SST variations, anomalies traveled into the tropical North Atlantic from the extratropical North Atlantic along the eastern boundary of the basin. The anomalies strengthened and resided in the tropical North Atlantic for several years, then frequently traveled northward into the mid-high-latitude North Atlantic along

A Decadal Climate Cycle in the North Atlantic Ocean as Simulated by the ECHO Coupled GCM.

NASA Astrophysics Data System (ADS)

Grötzner, A.; Latif, M.; Barnett, T. P.

1998-05-01

In this paper a decadal climate cycle in the North Atlantic that was derived from an extended-range integration with a coupled ocean-atmosphere general circulation model is described. The decadal mode shares many features with the observed decadal variability in the North Atlantic. The period of the simulated oscillation, however, is somewhat longer than that estimated from observations. While the observations indicate a period of about 12 yr, the coupled model simulation yields a period of about 17 yr. The cyclic nature of the decadal variability implies some inherent predictability at these timescales.The decadal mode is based on unstable air-sea interactions and must be therefore regarded as an inherently coupled mode. It involves the subtropical gyre and the North Atlantic oscillation. The memory of the coupled system, however, resides in the ocean and is related to horizontal advection and to the oceanic adjustment to low-frequency wind stress curl variations. In particular, it is found that variations in the intensity of the Gulf Stream and its extension are crucial to the oscillation. Although differing in details, the North Atlantic decadal mode and the North Pacific mode described by M. Latif and T. P. Barnett are based on the same fundamental mechanism: a feedback loop between the wind driven subtropical gyre and the extratropical atmospheric circulation.

Challenges in integrative approaches to modelling the marine ecosystems of the North Atlantic: Physics to fish and coasts to ocean

NASA Astrophysics Data System (ADS)

Holt, Jason; Icarus Allen, J.; Anderson, Thomas R.; Brewin, Robert; Butenschön, Momme; Harle, James; Huse, Geir; Lehodey, Patrick; Lindemann, Christian; Memery, Laurent; Salihoglu, Baris; Senina, Inna; Yool, Andrew

2014-12-01

It has long been recognised that there are strong interactions and feedbacks between climate, upper ocean biogeochemistry and marine food webs, and also that food web structure and phytoplankton community distribution are important determinants of variability in carbon production and export from the euphotic zone. Numerical models provide a vital tool to explore these interactions, given their capability to investigate multiple connected components of the system and the sensitivity to multiple drivers, including potential future conditions. A major driver for ecosystem model development is the demand for quantitative tools to support ecosystem-based management initiatives. The purpose of this paper is to review approaches to the modelling of marine ecosystems with a focus on the North Atlantic Ocean and its adjacent shelf seas, and to highlight the challenges they face and suggest ways forward. We consider the state of the art in simulating oceans and shelf sea physics, planktonic and higher trophic level ecosystems, and look towards building an integrative approach with these existing tools. We note how the different approaches have evolved historically and that many of the previous obstacles to harmonisation may no longer be present. We illustrate this with examples from the on-going and planned modelling effort in the Integrative Modelling Work Package of the EURO-BASIN programme.

Annual cycles of phytoplankton biomass in the subarctic Atlantic and Pacific Ocean

NASA Astrophysics Data System (ADS)

Westberry, Toby K.; Schultz, Patrick; Behrenfeld, Michael J.; Dunne, John P.; Hiscock, Michael R.; Maritorena, Stephane; Sarmiento, Jorge L.; Siegel, David A.

2016-02-01

High-latitude phytoplankton blooms support productive fisheries and play an important role in oceanic uptake of atmospheric carbon dioxide. In the subarctic North Atlantic Ocean, blooms are a recurrent feature each year, while in the eastern subarctic Pacific only small changes in chlorophyll (Chl) are seen over the annual cycle. Here we show that when evaluated using phytoplankton carbon biomass (Cphyto) rather than Chl, an annual bloom in the North Pacific is evident and can even rival blooms observed in the North Atlantic. The annual increase in subarctic Pacific phytoplankton biomass is not readily observed in the Chl record because it is paralleled by light- and nutrient-driven decreases in cellular pigment levels (Cphyto:Chl). Specifically, photoacclimation and iron stress effects on Cphyto:Chl oppose the biomass increase, leading to only modest changes in bulk Chl. The magnitude of the photoacclimation effect is quantified using descriptors of the near-surface light environment and a photophysiological model. Iron stress effects are diagnosed from satellite chlorophyll fluorescence data. Lastly, we show that biomass accumulation in the Pacific is slower than that in the Atlantic but is closely tied to similar levels of seasonal nutrient uptake in both basins. Annual cycles of satellite-derived Chl and Cphyto are reproduced by in situ autonomous profiling floats. These results contradict the long-standing paradigm that environmental conditions prevent phytoplankton accumulation in the subarctic Northeast Pacific and suggest a greater seasonal decoupling between phytoplankton growth and losses than traditionally implied. Further, our results highlight the role of physiological processes in shaping bulk properties, such as Chl, and their interpretation in studies of ocean ecosystem dynamics and climate change.

N2 Fixation by Unicellular Bacterioplankton from the Atlantic and Pacific Oceans: Phylogeny and In Situ Rates

PubMed Central

Falcón, Luisa I.; Carpenter, Edward J.; Cipriano, Frank; Bergman, Birgitta; Capone, Douglas G.

2004-01-01

N2-fixing proteobacteria (α and γ) and unicellular cyanobacteria are common in both the tropical North Atlantic and Pacific oceans. In near-surface waters proteobacterial nifH transcripts were present during both night and day while unicellular cyanobacterial nifH transcripts were present during the nighttime only, suggesting separation of N2 fixation and photosynthesis by unicellular cyanobacteria. Phylogenetic relationships among unicellular cyanobacteria from both oceans were determined after sequencing of a conserved region of 16S ribosomal DNA (rDNA) of cyanobacteria, and results showed that they clustered together, regardless of the ocean of origin. However, sequencing of nifH transcripts of unicellular cyanobacteria from both oceans showed that they clustered separately. This suggests that unicellular cyanobacteria from the tropical North Atlantic and subtropical North Pacific share a common ancestry (16S rDNA) and that potential unicellular N2 fixers have diverged (nifH). N2 fixation rates for unicellular bacterioplankton (including small cyanobacteria) from both oceans were determined in situ according to the acetylene reduction and 15N2 protocols. The results showed that rates of fixation by bacterioplankton can be almost as high as those of fixation by the colonial N2-fixing marine cyanobacteria Trichodesmium spp. in the tropical North Atlantic but that rates are much lower in the subtropical North Pacific. PMID:14766553

Meltwater and precipitation runoff to the North Atlantic, Arctic, and Gulf of Mexico from the Laurentide Ice Sheet and adjacent regions during the Younger Dryas

NASA Astrophysics Data System (ADS)

Teller, James T.

1990-12-01

Runoff from North America may have played a significant role in ocean circulation and climate change during the last deglaciation. Because the driving force behind such changes may have been related to salinity of the north flowing Atlantic Ocean conveyor circulation, it is critical to know the volume, timing, and location of fresh water entering the North Atlantic from the melting Laurentide Ice Sheet. During the Younger Dryas cold episode, 11,000-10,000 years B.P., there was a two-fold increase in the volume of meltwater plus precipitation runoff, to more than 1700 km³ yr-1, flowing through the St. Lawrence valley to the North Atlantic, mainly because retreating ice allowed the glacial Lake Agassiz basin to drain eastward into the Great Lakes at this time. There was a corresponding decline in discharge from Lake Agassiz through the Mississippi River to the Gulf of Mexico. Runoff to the Arctic Ocean also increased at about the beginning of the Younger Dryas, from 740 to 900 km³ yr-1, because of the capture of what is now the headwater region of the Mackenzie River watershed. This, in combination with rising sea level and warming climate, may have increased the amount of pack ice reaching the North Atlantic through the Norwegian Sea from the Arctic Ocean. At 10,000 years B.P., eastward overflow from the western interior of North America was blocked by advancing ice, again forcing overflow to the Gulf of Mexico and, possibly, to the northwest into the Arctic Ocean. Although total runoff to the oceans from all regions draining from the Laurentide Ice Sheet did not vary substantially between 12,000 and 9000 years B.P., if discharge to the Gulf of Mexico is excluded, fresh water reaching the North Atlantic averaged 4000 km³ yr-1 during the Younger Dryas, in contrast to 2870 km³ yr-1 just before this cold episode and 3440 km³ yr-1 just after it.

Dust transport and deposition observed from the Terra-Moderate Resolution Imaging Spectroradiometer (MODIS) spacecraft over the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Kaufman, Y. J.; Koren, I.; Remer, L. A.; Tanré, D.; Ginoux, P.; Fan, S.

2005-05-01

Meteorological observations, in situ data, and satellite images of dust episodes were used already in the 1970s to estimate that 100 Tg of dust are transported from Africa over the Atlantic Ocean every year between June and August and are deposited in the Atlantic Ocean and the Americas. Desert dust is a main source of nutrients to oceanic biota and the Amazon forest, but it deteriorates air quality, as shown for Florida. Dust affects the Earth radiation budget, thus participating in climate change and feedback mechanisms. There is an urgent need for new tools for quantitative evaluation of the dust distribution, transport, and deposition. The Terra spacecraft, launched at the dawn of the last millennium, provides the first systematic well-calibrated multispectral measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument for daily global analysis of aerosol. MODIS data are used here to distinguish dust from smoke and maritime aerosols and to evaluate the African dust column concentration, transport, and deposition. We found that 240 ± 80 Tg of dust are transported annually from Africa to the Atlantic Ocean, 140 ± 40 Tg are deposited in the Atlantic Ocean, 50 Tg fertilize the Amazon Basin (four times as previous estimates, thus explaining a paradox regarding the source of nutrition to the Amazon forest), 50 Tg reach the Caribbean, and 20 Tg return to Africa and Europe. The results are compared favorably with dust transport models for maximum particle diameter between 6 and 12 μm. This study is a first example of quantitative use of MODIS aerosol for a geophysical research.

The Lone Ranger Mission: Understanding Synthetic Polymer Microbe Interactions In the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Mielke, R.; Neal, A.; Stam, C. N.; Ferry, J. G.; Schlegel, R.; Tsapin, A. I.; Park, S.; Bhartia, R.; Salas, E.; Hug, W.; Behar, A. E.; Nadeau, J.

2011-12-01

Pollution is one of the most ubiquitous and insidious problems currently facing the oceans. As synthetic polymer debris degrades, it becomes increasingly accessible to organisms that forage or absorb food particles. However, research on this significant environmental pollution problem has not been able to keep up with the scope of the issue, since some of the first studies published in 1972 by Edward Carpenter. In January 2011, The Lone Ranger Atlantic Expedition, a collaboration between Blue Ocean Sciences (BOS) and the Schmidt Ocean Institute (SOI) transected the Atlantic Ocean covering 3,100 nautical miles sampling the first 15cm of the water column to investigate microbial interactions with synthetic polymer marine debris. Using established and novel techniques of Fourier transform infrared spectroscopy (FT-IR), scanning transmission electron microscopy (STEM), environmental scanning electron microscopy (ESEM), and gas chromatography-mass spectrometry (GC-MS), we were able to image and locate material degradation of pre-production, association of microbial biofilms, and accumulation of persistent organic pollutants (POP's) on environmental microplastics. We then used Spectroscopic Organic Analysis and ArcGIS mapping systems to observe the material degradation and the associated biofilm lattice on the environmental microplastics. This data sheds light on possible mechanisms of material weathering of synthetic polymers in deep ocean environments and new methods for identifying POP's association with them. These new techniques are highly transferable to many studies on material biofilm interactions in the environment.

Structure and origin of the J Anomaly Ridge, western North Atlantic Ocean

NASA Astrophysics Data System (ADS)

Tucholke, Brian E.; Ludwig, William J.

1982-11-01

The J Anomaly Ridge is a structural ridge or step in oceanic basement that extends southwest from the eastern end of the Grand Banks. It lies beneath the J magnetic anomaly at the young end (M-4 to M-0) of the M series magnetic anomalies. Its structural counterpart beneath the J anomaly in the eastern Atlantic is the Madeira-Tore Rise, but this feature has been overprinted by post-middle Cretaceous deformation and volcanism. In order to study the origin and evolution of the J Anomaly Ridge-Madeira-Tore Rise system, we obtained seismic refraction and multichannel reflection profiles across the J Anomaly Ridge near 39°N latitude. The western ridge flank consists of a series of crustal blocks downdropped along west-dipping normal faults, but the eastern slope to younger crust is gentle and relatively unfaulted. The western flank also is subparallel to seafloor isochrons, becoming younger to the south. Anomalously smooth basement caps the ridge crest, and it locally exhibits internal, eastward-dipping reflectors similar in configuration to those within subaerially emplaced basalt flows on Iceland. When isostatically corrected for sediment load, the northern part of the J Anomaly Ridge has basement depths about 1400 m shallower than in our study area, and deep sea drilling has shown that the northern ridge was subaerially exposed during the middle Cretaceous. We suggest that most of the system originated under subaerial conditions at the time of late-stage rifting between the adjacent Grand Banks and Iberia. The excess magma required to form the ridge may have been vented from a mantle plume beneath the Grand Banks-Iberia rift zone and channelled southward beneath the rift axis of the abutting Mid-Atlantic Ridge. Resulting edifice-building volcanism constructed the ridge system between anomalies M-4 and M-0, moving southward along the ridge axis at about 50 mm/yr. About M-0 time, when true drift began between Iberia and the Grand Banks, this southward venting rapidly

Cenozoic Circulation History of the North Atlantic Ocean From Seismic Stratigraphy of the Newfoundland Ridge Drift Complex

NASA Astrophysics Data System (ADS)

Boyle, P. R.; Romans, B.; Norris, R. D.; Tucholke, B. E.; Swift, S. A.; Sexton, P. F.

2014-12-01

In the North Atlantic Ocean, contour-following bottom currents have eroded regional unconformities and deposited contourite drifts that exceed two km in thickness and extend for 100s of km. The character of deep-water masses that are conveyed through ocean basins by such currents influence global heat transfer and ocean-atmosphere partitioning of CO2. The Newfoundland Ridge Drift Complex lies directly under the modern Deep Western Boundary Current southeast of Newfoundland, close to the site of overturning in the northwest Atlantic Ocean and at the intersection of the warm Gulf Stream and cool Labrador surface currents. To the south are regions of the western North Atlantic basin that are influenced by southern- as well as northern-sourced bottom waters. Here, we document the evolution of North Atlantic deep-water circulation by seismic-stratigraphic analysis of the long-lived and areally extensive Newfoundland Ridge Drift Complex. IODP Expedition 342 boreholes provide age control on seismic units, allowing sedimentation patterns to be placed in a temporal framework. We find three major phases of sedimentation: pre-contourite drift (~115-50 Ma), active contourite drift (~50-2.6 Ma), and late-contourite drift (~2.6-0 Ma). Bottom-current-controlled deposition of terrigenous-rich sediment began at ~50 Ma, which correlates to the onset of a long-term global cooling trend. A further change in deep circulation near the Eocene-Oligocene transition (~30 Ma) is indicated by more focused drift sedimentation with greatly increased accumulation rates and stratal architecture dominated by mud waves. At ~2.6 Ma to present the axis of drift accumulation shifted markedly towards shallower water depths, corresponding with the onset of Northern Hemisphere ice sheets. We discuss how these reorganizations of deep circulation correlate with results of other North Atlantic seismic stratigraphic studies to the north and south.

On the offshore dispersal of the Amazon's Plume in the North Atlantic: Comments on the paper by A. Longhurst, ``Seasonal cooling and blooming in tropical oceans''

NASA Astrophysics Data System (ADS)

Muller-Karger, F. E.; Richardson, P. L.; Mcgillicuddy, D.

1995-11-01

Coastal Zone Color Scanner (CZCS) satellite images show extensive plumes of discolored water extending from South America into the western tropical Atlantic. The most conspicuous plumes originate at the mouths of the Amazon and Orinoco Rivers, and plumes originating at smaller rivers can also be seen from space. In a recent paper by Longhurst (1993), the plume associated with the Amazon River was attributed to phytoplankton blooms stimulated by nutrients supplied via eddy upwelling. We revisit the argument that this plume is of riverine origin, and offer evidence that material present near continental margins can be advected offshore and trace circulation patterns in the adjacent ocean.

Limits on determining the skill of North Atlantic Ocean decadal predictions.

PubMed

Menary, Matthew B; Hermanson, Leon

2018-04-27

The northern North Atlantic is important globally both through its impact on the Atlantic Meridional Overturning Circulation (AMOC) and through widespread atmospheric teleconnections. The region has been shown to be potentially predictable a decade ahead with the skill of decadal predictions assessed against reanalyses of the ocean state. Here, we show that the prediction skill in this region is strongly dependent on the choice of reanalysis used for validation, and describe the causes. Multiannual skill in key metrics such as Labrador Sea density and the AMOC depends on more than simply the choice of the prediction model. Instead, this skill is related to the similarity between the nature of interannual density variability in the underlying climate model and the chosen reanalysis. The climate models used in these decadal predictions are also used in climate projections, which raises questions about the sensitivity of these projections to the models' innate North Atlantic density variability.

Meridional fluxes of dissolved organic matter in the North Atlantic Ocean

NASA Technical Reports Server (NTRS)

Walsh, John J.; Carder, Kendall L.; Mueller-Karger, Frank E.

1992-01-01

Biooptical estimates of gelbstoff and a few platinum measurements of dissolved organic carbon (DOCpt) are used to construct a budget of the meridional flux of DOC and dissolved organic nitrogen (DON) across 36 deg 25 min N in the North Atlantic from previous inverse models of water and element transport. Distinct southward subsurface fluxes of dissolved organic matter within subducted shelf water, cabelled slope water, and overturned basin water are inferred. Within two cases of a positive gradient of DOCpt between terrestrial/shelf and offshore stocks, the net equatorward exports of O2 and DOCpt from the northern North Atlantic yield molar ratios of 2.1 to 9.1, compared to the expected Redfield O2/C ratio of 1.3. It is concluded that some shelf export of DOC, with a positive gradient between coastal and oceanic stocks, as well as falling particles, are required to balance carbon, nitrogen, and oxygen budgets of the North Atlantic.

Mercury-Atlas 6 "Friendship 7" spacecraft is retrieved from the Atlantic Ocean

NASA Image and Video Library

1962-03-16

S62-00941 (20 Feb. 1962) --- The Mercury-Atlas 6 (MA-6) "Friendship 7" spacecraft is retrieved from the Atlantic Ocean following astronaut John H. Glenn Jr.'s three-orbit space mission. In this view, the capsule is still in the water, with retrieval cable connected to it. Photo credit: NASA

Climate change and oceanic barriers: genetic differentiation in Pomatomus saltatrix (Pisces: Pomatomidae) in the North Atlantic Ocean and the Mediterranean Sea.

PubMed

Pardiñas, A F; Campo, D; Pola, I G; Miralles, L; Juanes, F; Garcia-Vazquez, E

2010-11-01

Nucleotide variation of partial cytochrome b sequences was analysed in the bluefish Pomatomus saltatrix to investigate the population-structuring roles of climate change and oceanic barriers. Western and eastern North Atlantic Ocean populations appeared to be totally isolated, with the latter connected to the Mediterranean Sea within which further structuring occurred. © 2010 The Authors. Journal of Fish Biology © 2010 The Fisheries Society of the British Isles.

Saharan dust as a causal factor of hemispheric asymmetry in aerosols and cloud cover over the tropical Atlantic Ocean

DOE PAGES

Kishcha, Pavel; Da Sliva, Arlindo; Starobinets, Boris; ...

2015-07-09

Meridional distribution of aerosol optical thickness (AOT) over the tropical Atlantic Ocean (30°N – 30°S) was analyzed to assess seasonal variations of meridional AOT asymmetry. Ten-year MERRA Aerosol Reanalysis (MERRAero) data (July 2002 – June 2012) confirms that the Sahara desert emits a significant amount of dust into the atmosphere over the Atlantic Ocean. Only over the Atlantic Ocean did MERRAero show that desert dust dominates other aerosol species and is responsible for meridional aerosol asymmetry between the tropical North and South Atlantic. Over the 10-year period under consideration, both MISR measurements and MERRAero data showed a pronounced meridional AOTmore » asymmetry. The meridional AOT asymmetry, characterized by the hemispheric ratio (RAOT) of AOT averaged separately over the North and over the South Atlantic, was about 1.7. Seasonally, meridional AOT asymmetry over the Atlantic was the most pronounced between March and July, when dust presence is maximal (RAOT ranged from 2 to 2.4). There was no noticeable meridional aerosol asymmetry in total AOT from September to October. During this period the contribution of carbonaceous aerosols to total AOT in the South Atlantic was comparable to the contribution of dust aerosols to total AOT in the North Atlantic. During the same 10-year period, MODIS cloud fraction (CF) data showed that there was no noticeable asymmetry in meridional CF distribution in different seasons (the hemispheric ratio of CF ranged from 1.0 to 1.2). MODIS CF data illustrated significant cloud cover (CF of 0.7 – 0.9) with limited precipitation ability along the Saharan Air Layer.« less

Organic and total mercury levels in bigeye tuna, Thunnus obesus, harvested by Taiwanese fishing vessels in the Atlantic and Indian Oceans.

PubMed

Chen, M H; Teng, P Y; Chen, C Y; Hsu, C C

2011-01-01

Muscle samples of 121 and 110 bigeye tuna (Thunnus obesus) caught by Taiwanese long-line fishing vessels in the Atlantic and Indian Oceans, respectively, were used to analyze total mercury (THg) and organic mercury (OHg) content. The overall THg and OHg concentrations were 0.786 ± 0.386 (0.214-3.133) and 0.595 ± 0.238 (0.143-2.222) mg kg⁻¹ wet weight, respectively, similar to the results of previous studies. Our findings, however, reflected the highest THg and OHg concentrations for the species in each ocean among the published data. Mean THg and OHg concentrations in Atlantic tuna were significantly (p < 0.05) higher than those in Indian tuna. Two of 121 samples of tuna from the Atlantic Ocean, but no samples from the Indian Ocean, had levels of OHg above 2 mg kg⁻¹ wet weight set by the Department of Health Taiwan, and 13 of 121 samples of tuna from the Atlantic Ocean and three of 110 samples from the Indian Ocean had levels of OHg above 1 mg kg⁻¹ wet weight set by US FDA and WHO. Accordingly, for adult Taiwanese men and women with average body weight of 65 and 55 kg, respectively, the maximum allowable weekly intake of bigeye tuna is suggested to be 170 and 145 g, respectively.

Surface ocean carbon dioxide during the Atlantic Meridional Transect (1995-2013); evidence of ocean acidification

NASA Astrophysics Data System (ADS)

Kitidis, Vassilis; Brown, Ian; Hardman-Mountford, Nicholas; Lefèvre, Nathalie

2017-11-01

Here we present more than 21,000 observations of carbon dioxide fugacity in air and seawater (fCO2) along the Atlantic Meridional Transect (AMT) programme for the period 1995-2013. Our dataset consists of 11 southbound and 2 northbound cruises in boreal autumn and spring respectively. Our paper is primarily focused on change in the surface-ocean carbonate system during southbound cruises. We used observed fCO2 and total alkalinity (TA), derived from salinity and temperature, to estimate dissolved inorganic carbon (DIC) and pH (total scale). Using this approach, estimated pH was consistent with spectrophotometric measurements carried out on 3 of our cruises. The AMT cruises transect a range of biogeographic provinces where surface Chlorophyll-α spans two orders of magnitude (mesotrophic high latitudes to oligotrophic subtropical gyres). We found that surface Chlorophyll-α was negatively correlated with fCO2, but that the deep chlorophyll maximum was not a controlling variable for fCO2. Our data show clear evidence of ocean acidification across 100° of latitude in the Atlantic Ocean. Over the period 1995-2013 we estimated annual rates of change in: (a) sea surface temperature of 0.01 ± 0.05 °C, (b) seawater fCO2 of 1.44 ± 0.84 μatm, (c) DIC of 0.87 ± 1.02 μmol per kg and (d) pH of -0.0013 ± 0.0009 units. Monte Carlo simulations propagating the respective analytical uncertainties showed that the latter were < 5% of the observed trends. Seawater fCO2 increased at the same rate as atmospheric CO2.

Impact of tropical Atlantic sea-surface temperature biases on the simulated atmospheric circulation and precipitation over the Atlantic region: An ECHAM6 model study

NASA Astrophysics Data System (ADS)

Eichhorn, Astrid; Bader, Jürgen

2017-09-01

As many coupled atmosphere-ocean general circulation models, the coupled Earth System Model developed at the Max Planck Institute for Meteorology suffers from severe sea-surface temperature (SST) biases in the tropical Atlantic. We performed a set of SST sensitivity experiments with its atmospheric model component ECHAM6 to understand the impact of tropical Atlantic SST biases on atmospheric circulation and precipitation. The model was forced by a climatology of observed global SSTs to focus on simulated seasonal and annual mean state climate. Through the superposition of varying tropical Atlantic bias patterns extracted from the MPI-ESM on top of the control field, this study investigates the relevance of the seasonal variation and spatial structure of tropical Atlantic biases for the simulated response. Results show that the position and structure of the Intertropical Convergence Zone (ITCZ) across the Atlantic is significantly affected, exhibiting a dynamically forced shift of annual mean precipitation maximum to the east of the Atlantic basin as well as a southward shift of the oceanic rain belt. The SST-induced changes in the ITCZ in turn affect seasonal rainfall over adjacent continents. However not only the ITCZ position but also other effects arising from biases in tropical Atlantic SSTs, e.g. variations in the wind field, change the simulation of precipitation over land. The seasonal variation and spatial pattern of tropical Atlantic SST biases turns out to be crucial for the simulated atmospheric response and is essential for analyzing the contribution of SST biases to coupled model mean state biases. Our experiments show that MPI-ESM mean-state biases in the Atlantic sector are mainly driven by SST biases in the tropical Atlantic while teleconnections from other basins seem to play a minor role.

Tiger sharks can connect equatorial habitats and fisheries across the Atlantic Ocean basin.

PubMed

Afonso, André S; Garla, Ricardo; Hazin, Fábio H V

2017-01-01

Increasing our knowledge about the spatial ecology of apex predators and their interactions with diverse habitats and fisheries is necessary for understanding the trophic mechanisms that underlie several aspects of marine ecosystem dynamics and for guiding informed management policies. A preliminary assessment of tiger shark (Galeocerdo cuvier) population structure off the oceanic insular system of Fernando de Noronha (FEN) and the large-scale movements performed by this species in the equatorial Atlantic Ocean was conducted using longline and handline fishing gear and satellite telemetry. A total of 25 sharks measuring 175-372 cm in total length (TL) were sampled. Most sharks were likely immature females ranging between 200 and 260 cm TL, with few individuals < 200 cm TL being caught. This contrasts greatly with the tiger shark size-distribution previously reported for coastal waters off the Brazilian mainland, where most individuals measured < 200 cm TL. Also, the movements of 8 individuals measuring 202-310 cm TL were assessed with satellite transmitters for a combined total of 757 days (mean = 94.6 days∙shark-1; SD = 65.6). These sharks exhibited a considerable variability in their horizontal movements, with three sharks showing a mostly resident behavior around FEN during the extent of the respective tracks, two sharks traveling west to the South American continent, and two sharks moving mostly along the middle of the oceanic basin, one of which ending up in the northern hemisphere. Moreover, one shark traveled east to the African continent, where it was eventually caught by fishers from Ivory Coast in less than 474 days at liberty. The present results suggest that young tiger sharks measuring < 200 cm TL make little use of insular oceanic habitats from the western South Atlantic Ocean, which agrees with a previously-hypothesized ontogenetic habitat shift from coastal to oceanic habitats experienced by juveniles of this species in this region. In addition

Tiger sharks can connect equatorial habitats and fisheries across the Atlantic Ocean basin

PubMed Central

Garla, Ricardo; Hazin, Fábio H. V.

2017-01-01

Increasing our knowledge about the spatial ecology of apex predators and their interactions with diverse habitats and fisheries is necessary for understanding the trophic mechanisms that underlie several aspects of marine ecosystem dynamics and for guiding informed management policies. A preliminary assessment of tiger shark (Galeocerdo cuvier) population structure off the oceanic insular system of Fernando de Noronha (FEN) and the large-scale movements performed by this species in the equatorial Atlantic Ocean was conducted using longline and handline fishing gear and satellite telemetry. A total of 25 sharks measuring 175–372 cm in total length (TL) were sampled. Most sharks were likely immature females ranging between 200 and 260 cm TL, with few individuals < 200 cm TL being caught. This contrasts greatly with the tiger shark size-distribution previously reported for coastal waters off the Brazilian mainland, where most individuals measured < 200 cm TL. Also, the movements of 8 individuals measuring 202–310 cm TL were assessed with satellite transmitters for a combined total of 757 days (mean = 94.6 days∙shark-1; SD = 65.6). These sharks exhibited a considerable variability in their horizontal movements, with three sharks showing a mostly resident behavior around FEN during the extent of the respective tracks, two sharks traveling west to the South American continent, and two sharks moving mostly along the middle of the oceanic basin, one of which ending up in the northern hemisphere. Moreover, one shark traveled east to the African continent, where it was eventually caught by fishers from Ivory Coast in less than 474 days at liberty. The present results suggest that young tiger sharks measuring < 200 cm TL make little use of insular oceanic habitats from the western South Atlantic Ocean, which agrees with a previously-hypothesized ontogenetic habitat shift from coastal to oceanic habitats experienced by juveniles of this species in this region. In

Black carbon concentrations and sources in the marine boundary layer of the tropical Atlantic Ocean using four methodologies

EPA Science Inventory

Combustion-derived aerosols in the marine boundary layer have been poorly studied, especially in remote environments such as the open Atlantic Ocean. The tropical Atlantic has the potential to contain a high concentration of aerosols, such as black carbon, due to the African emis...

Exceptional twentieth-century slowdown in Atlantic Ocean overturning circulation

NASA Astrophysics Data System (ADS)

Rahmstorf, Stefan; Box, Jason E.; Feulner, Georg; Mann, Michael E.; Robinson, Alexander; Rutherford, Scott; Schaffernicht, Erik J.

2015-05-01

Possible changes in Atlantic meridional overturning circulation (AMOC) provide a key source of uncertainty regarding future climate change. Maps of temperature trends over the twentieth century show a conspicuous region of cooling in the northern Atlantic. Here we present multiple lines of evidence suggesting that this cooling may be due to a reduction in the AMOC over the twentieth century and particularly after 1970. Since 1990 the AMOC seems to have partly recovered. This time evolution is consistently suggested by an AMOC index based on sea surface temperatures, by the hemispheric temperature difference, by coral-based proxies and by oceanic measurements. We discuss a possible contribution of the melting of the Greenland Ice Sheet to the slowdown. Using a multi-proxy temperature reconstruction for the AMOC index suggests that the AMOC weakness after 1975 is an unprecedented event in the past millennium (p > 0.99). Further melting of Greenland in the coming decades could contribute to further weakening of the AMOC.

A new genus and species of Platyischnopidae (Amphipoda: Gammaridea) from the Argentine sea, South-West Atlantic ocean.

PubMed

Chiesa, Ignacio L; Alonso, Gloria M

2014-05-30

The family Platyischnopidae is herein reported for the first time in the Argentine Sea, South-West Atlantic Ocean. A new genus and species, Platyisao holodividum gen. et. sp. nov., collected off the coast of Buenos Aires and Río Negro provinces, is fully described and illustrated. Platyisao gen. nov. is distinguished from the eight other genera of Platyischnopidae by the gnathopods subchelate, and the telson elongate, completely cleft. In addition, the distribution of Tiburonella viscana (Barnard J.L., 1964), up to now known in the South-West Atlantic Ocean from Brazilian waters, is extended to the coast off Buenos Aires province, Argentina.

Climate and vegetation changes around the Atlantic Ocean resulting from changes in the meridional overturning circulation during deglaciation

NASA Astrophysics Data System (ADS)

Handiani, D.; Paul, A.; Dupont, L.

2012-07-01

The Bølling-Allerød (BA, starting ~ 14.5 ka BP) is one of the most pronounced abrupt warming periods recorded in ice and pollen proxies. The leading explanation of the cause of this warming is a sudden increase in the rate of deepwater formation in the North Atlantic Ocean and the resulting effect on the heat transport by the Atlantic Meridional Overturning Circulation (AMOC). In this study, we used the University of Victoria (UVic) Earth System-Climate Model (ESCM) to run simulations, in which a freshwater perturbation initiated a BA-like warming period. We found that under present climate conditions, the AMOC intensified when freshwater was added to the Southern Ocean. However, under Heinrich event 1 (HE1, ~ 16 ka BP) climate conditions, the AMOC only intensified when freshwater was extracted from the North Atlantic Ocean, possibly corresponding to an increase in evaporation or a decrease in precipitation in this region. The intensified AMOC led to a warming in the North Atlantic Ocean and a cooling in the South Atlantic Ocean, resembling the bipolar seesaw pattern typical of the last glacial period. In addition to the physical response, we also studied the simulated vegetation response around the Atlantic Ocean region. Corresponding with the bipolar seesaw hypothesis, the rainbelt associated with the Intertropical Convergence Zone (ITCZ) shifted northward and affected the vegetation pattern in the tropics. The most sensitive vegetation area was found in tropical Africa, where grass cover increased and tree cover decreased under dry climate conditions. An equal but opposite response to the collapse and recovery of the AMOC implied that the change in vegetation cover was transient and robust to an abrupt climate change such as during the BA period, which is also supported by paleovegetation data. The results are in agreement with paleovegetation records from Western tropical Africa, which also show a reduction in forest cover during this time period. Further

Dueling Deglacial Depth Transects: A Synthesis of Isotope Records from the South Atlantic and Pacific Oceans Provides Insight into Deglacial Ocean Circulation

NASA Astrophysics Data System (ADS)

Sikes, E. L.; Allen, K. A.; Lund, D. C.

2016-12-01

The end of the last ice age was marked by rapid increases in atmospheric CO2 and changes in ocean circulation and seawater δ13C and Δ14C, suggesting that enhanced ventilation of the deep ocean may have released sequestered CO2 to the atmosphere. Here we compare depth transects of Δ14C and high-resolution Cibicidoides sp. δ13C and δ18O records from the Southwest Pacific and the Southwest Atlantic to gain insight into the changing extent and composition of water masses in the Southern Hemisphere. Our vertical transects document that during the Last Glacial Maximum (LGM), water mass properties and boundaries in the Southwest Atlantic and Pacific were very different from one another and from their respective modern profiles. The shallow to deep δ13C difference (Δδ13C, 660- 2500 m) in the Pacific was 1.7‰, more than double the Holocene value ( 0.7‰) and a deep watermass boundary was situated above 1600m. LGM Δδ13C in the Atlantic was similar to the Pacific, but the deep geochemical front was situated at 2500 m (as observed previously; e.g. Hoffman and Lund, 2012). At the onset of Heinrich Stadial 1 (HS1; 18 - 14.5 ka), changes in the shallow isotope records (< 1500 m) from the two basins differed, indicating independent controls on intermediate water composition/formation in these two ocean basins. During HS1 in the Pacific, rapid δ13C and Δ14C enrichment above 1600 m coincided with δ13C depletion in Atlantic waters between 1500 m and 2500 m. Benthic δ13C below 2500 m in both basins and D14C in the Pacific remained depleted until the Antarctic Cold Reversal (ACR; 14.7 to 12.7 ka). During the ACR, Pacific Δ14C below 1600 m increased while both the Atlantic and Pacific experienced a rapid increase in δ13C and decrease in δ18O below 2500 m. These simultaneous isotopic shifts in the Pacific and Atlantic support the idea of a widespread pulse of deep-water ventilation driven by the resumption of North Atlantic Deep Water formation during the ACR. Overall

Microbial diversity from chlorophyll maximum, oxygen minimum and bottom zones in the southwestern Atlantic Ocean

NASA Astrophysics Data System (ADS)

Medina-Silva, Renata; de Oliveira, Rafael R.; Pivel, Maria A. G.; Borges, Luiz G. A.; Simão, Taiz L. L.; Pereira, Leandro M.; Trindade, Fernanda J.; Augustin, Adolpho H.; Valdez, Fernanda P.; Eizirik, Eduardo; Utz, Laura R. P.; Groposo, Claudia; Miller, Dennis J.; Viana, Adriano R.; Ketzer, João M. M.; Giongo, Adriana

2018-02-01

Conspicuous physicochemical vertical stratification in the deep sea is one of the main forces driving microbial diversity in the oceans. Oxygen and sunlight availability are key factors promoting microbial diversity throughout the water column. Ocean currents also play a major role in the physicochemical stratification, carrying oxygen down to deeper zones as well as moving deeper water masses up towards shallower depths. Water samples within a 50-km radius in a pockmark location of the southwestern Atlantic Ocean were collected and the prokaryotic communities from different water depths - chlorophyll maximum, oxygen minimum and deep-sea bottom (down to 1355 m) - were described. At phylum level, Proteobacteria were the most frequent in all water depths, Cyanobacteria were statistically more frequent in chlorophyll maximum zone, while Thaumarchaeota were significantly more abundant in both oxygen minimum and bottom waters. The most frequent microorganism in the chlorophyll maximum and oxygen minimum zones was a Pelagibacteraceae operational taxonomic unit (OTU). At the bottom, the most abundant genus was the archaeon Nitrosopumilus. Beta diversity analysis of the 16S rRNA gene sequencing data uncovered in this study shows high spatial heterogeneity among water zones communities. Our data brings important contribution for the characterisation of oceanic microbial diversity, as it consists of the first description of prokaryotic communities occurring in different oceanic water zones in the southwestern Atlantic Ocean.

Fluorescence of dissolved organic matter: A comparison of north Pacific and north Atlantic Oceans during April 1991

NASA Technical Reports Server (NTRS)

Hoge, Frank E.; Swift, Robert N.; Yungel, James K.; Vodacek, Anthony

1993-01-01

Profiles of airborne-laser-induced fluorescence emission from dissolved organic matter in the upper ocean have been produced and compared for the Southern California Bight (SCB) and the Mid-Atlantic Bight (MAB). Findings were as follows. (1) The fluorescent components of dissolved organic matter (FDOM) are present in easily measurable quantities from near shore to well over 300 km offshore in the SCB and are likewise easily measurable in the coastal, shelf, slope, and Gulf Stream waters of the MAB. (2) The reange of FDOM in the MAB is considerably greater than that in the SCB. (3) The lowest FDOM levels observed in the SCB were higher than those found in the Gulf Stream. (4) The onshore-to-offshore spatial gradient of the FDOM was found to be considerably lower in the SCB than in the MAB, with the highest levels of FDOM being found immediately adjacent to the coast in the MAB. This suggests that the water adjacent to the SCB shoreline is not as strongly influenced by terrestrial and estuarine sources of FDOM as the MAB is. (5) The spatial distribution of the FDOM within both the SCB and the MAB is frequently coherent with the spatial distribution of chlorophyll determined form the concurrent airborne- laser- induced phytoplankton pigment fluorescence measurements. However, distinct noncoherency is sometimes observed, especially at water mass boundaries.

GIS Methodic and New Database for Magmatic Rocks. Application for Atlantic Oceanic Magmatism.

NASA Astrophysics Data System (ADS)

Asavin, A. M.

2001-12-01

There are several geochemical Databases in INTERNET available now. There one of the main peculiarities of stored geochemical information is geographical coordinates of each samples in those Databases. As rule the software of this Database use spatial information only for users interface search procedures. In the other side, GIS-software (Geographical Information System software),for example ARC/INFO software which using for creation and analyzing special geological, geochemical and geophysical e-map, have been deeply involved with geographical coordinates for of samples. We join peculiarities GIS systems and relational geochemical Database from special software. Our geochemical information system created in Vernadsky Geological State Museum and institute of Geochemistry and Analytical Chemistry from Moscow. Now we tested system with data of geochemistry oceanic rock from Atlantic and Pacific oceans, about 10000 chemical analysis. GIS information content consist from e-map covers Wold Globes. Parts of these maps are Atlantic ocean covers gravica map (with grid 2''), oceanic bottom hot stream, altimeteric maps, seismic activity, tectonic map and geological map. Combination of this information content makes possible created new geochemical maps and combination of spatial analysis and numerical geochemical modeling of volcanic process in ocean segment. Now we tested information system on thick client technology. Interface between GIS system Arc/View and Database resides in special multiply SQL-queries sequence. The result of the above gueries were simple DBF-file with geographical coordinates. This file act at the instant of creation geochemical and other special e-map from oceanic region. We used more complex method for geophysical data. From ARC\\View we created grid cover for polygon spatial geophysical information.

Pacific and Atlantic Ocean influences on multidecadal drought frequency in the United States

USGS Publications Warehouse

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

2004-01-01

More than half (52%) of the spatial and temporal variance in multidecadal drought frequency over the conterminous United States is attributable to the Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO). An additional 22% of the variance in drought frequency is related to a complex spatial pattern of positive and negative trends in drought occurrence possibly related to increasing Northern Hemisphere temperatures or some other unidirectional climate trend. Recent droughts with broad impacts over the conterminous U.S. (1996, 1999-2002) were associated with North Atlantic warming (positive AMO) and north-eastern and tropical Pacific cooling (negative PDO). Much of the long-term predictability of drought frequency may reside in the multidecadal behavior of the North Atlantic Ocean. Should the current positive AMO (warm North Atlantic) conditions persist into the upcoming decade, we suggest two possible drought scenarios that resemble the continental-scale patterns of the 1930s (positive PDO) and 1950s (negative PDO) drought.

Deep Ocean Circulation and Nutrient Contents from Atlantic-Pacific Gradients of Neodymium and Carbon Isotopes During the Last 1 Ma

NASA Astrophysics Data System (ADS)

Piotrowski, A. M.; Elderfield, H.; Howe, J. N. W.

2014-12-01

The last few million years saw changing boundary conditions to the Earth system which set the stage for bi-polar glaciation and Milankovich-forced glacial-interglacial cycles which dominate Quaternary climate variability. Recent studies have highlighted the relative importance of temperature, ice volume and ocean circulation changes during the Mid-Pleistocene Transition at ~900 ka (Elderfield et al., 2012, Pena and Goldstein, 2014). Reconstructing the history of global deep water mass propagation and its carbon content is important for fully understanding the ocean's role in amplifying Milankovich changes to cause glacial-interglacial transitions. A new foraminiferal-coating Nd isotope record from ODP Site 1123 on the deep Chatham Rise is interpreted as showing glacial-interglacial changes in the bottom water propagation of Atlantic-sourced waters into the Pacific via the Southern Ocean during the last 1 million years. This is compared to globally-distributed bottom water Nd isotope records; including a new deep western equatorial Atlantic Ocean record from ODP Site 929, as well as published records from ODP 1088 and Site 1090 in the South Atlantic (Pena and Goldstein, 2014), and ODP 758 in the deep Indian Ocean (Gourlan et al., 2010). Atlantic-to-Pacific gradients in deep ocean neodymium isotopes are constructed for key time intervals to elucidate changes in deep water sourcing and circulation pathways through the global ocean. Benthic carbon isotopes are used to estimate deep water nutrient contents of deep water masses and constrain locations and modes of deep water formation. References: Elderfield et al. Science 337, 704 (2012) Pena and Goldstein, Science 345, 318 (2014) Gourlan et al., Quaternary Science Reviews 29, 2484-2498 (2010)

Impact of realistic future ice sheet discharge on the Atlantic ocean

NASA Astrophysics Data System (ADS)

van den Berk, Jelle

2015-04-01

Royal Netherlands Meteorological Institute, De Bilt, The Netherlands A high-end scenario of polar ice loss from the Greenland and Antarctic ice sheet is presented with separate projections for different mass-loss sites up to the year 2100. The resultant freshwater forcing is applied to a global climate model and the effects on sea-level rise are discussed. The simulations show strong sea level rise on the Antarctic continental shelves. To separate the effects of atmospheric warming and melt water we then ran four simulations. One without either forcing, one with both and two with one of each separately. Melt water leads to a slight additional depression of the Atlantic overturning circulation, but a strong decrease remains absent. The bulk of the strength reduction is due to higher atmospheric temperatures which inhibits deep water formation in the North Atlantic. The melt water freshens the upper layers of the ocean, but does not strongly impact buoyancy. The balance between North Atlantic Deep Water and Antarctic Bottom Water must then remain relatively unaffected. Only applying the melt water forcing to the Northern Hemisphere does not lead to a stronger effect. We conclude that the meltwater scenario only impacts the overturning circulation superficially because the deeper ocean is not affected. Transport through Bering Strait and across the zonal section at the latitude of Cape Agulhas is increased by increased atmospheric temperatures and adds some inertia to these transports. Reversing the atmospheric forcing bears this out when the transport then further increases. The freshwater, however, mitigates this inertia somewhat.

Taxonomy of quaternary deep-sea ostracods from the Western North Atlantic ocean

USGS Publications Warehouse

Yasuhara, Moriaki; Okahashi, H.; Cronin, T. M.

2009-01-01

Late Quaternary sediments from Ocean Drilling Program (ODP) Hole 1055B, Carolina Slope, western North Atlantic (32??47.041??? N, 76??17.179??? W; 1798m water depth) were examined for deep-sea ostracod taxonomy. A total of 13933 specimens were picked from 207 samples and c. 120 species were identified. Among them, 87 species were included and illustrated in this paper. Twenty-eight new species are described. The new species are: Ambocythere sturgio, Argilloecia abba, Argilloecia caju, Argilloecia keigwini, Argilloecia robinwhatleyi, Aversovalva carolinensis, Bythoceratina willemvandenboldi, Bythocythere eugeneschornikovi, Chejudocythere tenuis, Cytheropteron aielloi, Cytheropteron demenocali, Cytheropteron didieae, Cytheropteron richarddinglei, Cytheropteron fugu, Cytheropteron guerneti, Cytheropteron richardbensoni, Eucytherura hazeli, Eucytherura mayressi, Eucytherura namericana, Eucytherura spinicorona, Posacythere hunti, Paracytherois bondi, Pedicythere atroposopetasi, Pedicythere kennettopetasi, Pedicythere klothopetasi, Pedicythere lachesisopetasi, Ruggieriella mcmanusi and Xestoleberis oppoae. Taxonomic revisions of several common species were made to reduce taxonomic uncertainty in the literature. This study provides a robust taxonomic baseline for application to palaeoceanographical reconstruction and biodiversity analyses in the deep and intermediate-depth environments of the North Atlantic Ocean. ?? The Palaeontological Association, 2009.

Biogeochemical Trends and Their Ecosystem Impacts in Atlantic Canada

NASA Astrophysics Data System (ADS)

Fennel, Katja; Rutherford, Krysten; Kuhn, Angela; Zhang, Wenxia; Brennan, Katie; Zhang, Rui

2017-04-01

The representation of coastal oceans in global biogeochemical models is a challenge, yet the ecosystems in these regions are most vulnerable to the combined stressors of ocean warming, deoxygenation, acidification, eutrophication and fishing. Coastal regions also have large air-sea fluxes of CO2, making them an important but poorly quantified component of the global carbon cycle, and are the most relevant for human activities. Regional model applications that are nested within large-scale or global models are necessary for detailed studies of coastal regions. We present results from such a regional biogeochemical model for the northwestern North Atlantic shelves and adjacent deep ocean of Atlantic Canada. The model is an implementation of the Regional Ocean Modeling System (ROMS) and includes an NPZD-type nitrogen cycle model with explicit representation of dissolved oxygen and inorganic carbon. The region is at the confluence of the Gulf Stream and Labrador Current making it highly dynamic, a challenge for analysis and prediction, and prone to large changes. Historically a rich fishing ground, coastal ecosystems in Atlantic Canada have undergone dramatic changes including the collapse of several economically important fish stocks and the listing of many species as threatened or endangered. Furthermore it is unclear whether the region is a net source or sink of atmospheric CO2 with estimates of the size and direction of the net air-sea CO2 flux remaining controversial. We will discuss simulated patterns of primary production, inorganic carbon fluxes and oxygen trends in the context of circulation features and shelf residence times for the present ocean state and present future projections.

Liberty Bell 7 is retrieved from Atlantic Ocean

NASA Technical Reports Server (NTRS)

1999-01-01

Retrieved from the ocean floor three miles deep, the Liberty Bell 7 Project Mercury capsule is revealed to photographers and the media in Port Canaveral, Fla. The capsule was found and raised by Curt Newport (left), leading an expedition sponsored by the Discovery Channel. After its successful 16-minute suborbital flight on July 21, 1961, the Liberty Bell 7, with astronaut Virgil 'Gus' Grissom aboard, splashed down in the Atlantic Ocean. A prematurely jettisoned hatch caused the capsule to flood and a Marine rescue helicopter was unable to lift it. It quickly sank to a three-mile depth. Grissom was rescued but his spacecraft remained lost on the ocean floor, until now. An underwater salvage expert, Newport located the capsule through modern technology, and after one abortive attempt, successfully raised it and brought it to Port Canaveral. The recovery of Liberty Bell 7 fulfilled a 14-year dream for the expedition leader. The capsule is being moved to the Kansas Cosmosphere and Space Center in Hutchinson, Kansas, where it will be restored for eventual public display. Newport has also been involved in salvage operations of the Space Shuttle Challenger and TWA Flight 800 that crashed off the coast of Long Island, N.Y.

The salinity signature of the cross-shelf exchanges in the Southwestern Atlantic Ocean: Satellite observations.

PubMed

Guerrero, Raul A; Piola, Alberto R; Fenco, Harold; Matano, Ricardo P; Combes, Vincent; Chao, Yi; James, Corinne; Palma, Elbio D; Saraceno, Martin; Strub, P Ted

2014-11-01

Satellite-derived sea surface salinity (SSS) data from Aquarius and SMOS are used to study the shelf-open ocean exchanges in the western South Atlantic near 35°S. Away from the tropics, these exchanges cause the largest SSS variability throughout the South Atlantic. The data reveal a well-defined seasonal pattern of SSS during the analyzed period and of the location of the export of low-salinity shelf waters. In spring and summer, low-salinity waters over the shelf expand offshore and are transferred to the open ocean primarily southeast of the river mouth (from 36°S to 37°30'S). In contrast, in fall and winter, low-salinity waters extend along a coastal plume and the export path to the open ocean distributes along the offshore edge of the plume. The strong seasonal SSS pattern is modulated by the seasonality of the along-shelf component of the wind stress over the shelf. However, the combined analysis of SSS, satellite-derived sea surface elevation and surface velocity data suggest that the precise location of the export of shelf waters depends on offshore circulation patterns, such as the location of the Brazil Malvinas Confluence and mesoscale eddies and meanders of the Brazil Current. The satellite data indicate that in summer, mixtures of low-salinity shelf waters are swiftly driven toward the ocean interior along the axis of the Brazil/Malvinas Confluence. In winter, episodic wind reversals force the low-salinity coastal plume offshore where they mix with tropical waters within the Brazil Current and create a warmer variety of low-salinity waters in the open ocean. Satellite salinity sensors capture low-salinity detrainment events from shelves SW Atlantic low-salinity detrainments cause highest basin-scale variability In summer low-salinity detrainments cause extended low-salinity anomalies.

The salinity signature of the cross-shelf exchanges in the Southwestern Atlantic Ocean: Satellite observations

PubMed Central

Guerrero, Raul A; Piola, Alberto R; Fenco, Harold; Matano, Ricardo P; Combes, Vincent; Chao, Yi; James, Corinne; Palma, Elbio D; Saraceno, Martin; Strub, P Ted

2014-01-01

Satellite-derived sea surface salinity (SSS) data from Aquarius and SMOS are used to study the shelf-open ocean exchanges in the western South Atlantic near 35°S. Away from the tropics, these exchanges cause the largest SSS variability throughout the South Atlantic. The data reveal a well-defined seasonal pattern of SSS during the analyzed period and of the location of the export of low-salinity shelf waters. In spring and summer, low-salinity waters over the shelf expand offshore and are transferred to the open ocean primarily southeast of the river mouth (from 36°S to 37°30′S). In contrast, in fall and winter, low-salinity waters extend along a coastal plume and the export path to the open ocean distributes along the offshore edge of the plume. The strong seasonal SSS pattern is modulated by the seasonality of the along-shelf component of the wind stress over the shelf. However, the combined analysis of SSS, satellite-derived sea surface elevation and surface velocity data suggest that the precise location of the export of shelf waters depends on offshore circulation patterns, such as the location of the Brazil Malvinas Confluence and mesoscale eddies and meanders of the Brazil Current. The satellite data indicate that in summer, mixtures of low-salinity shelf waters are swiftly driven toward the ocean interior along the axis of the Brazil/Malvinas Confluence. In winter, episodic wind reversals force the low-salinity coastal plume offshore where they mix with tropical waters within the Brazil Current and create a warmer variety of low-salinity waters in the open ocean. Key Points Satellite salinity sensors capture low-salinity detrainment events from shelves SW Atlantic low-salinity detrainments cause highest basin-scale variability In summer low-salinity detrainments cause extended low-salinity anomalies PMID:26213672

Convective Lofting Links Indian Ocean Air Pollution to Paradoxical South Atlantic Ozone Maxima

NASA Technical Reports Server (NTRS)

Chatfield, Robert B.; Guan, Hong; Thompson, Anne M.; Witte, Jacquelyn C.

2003-01-01

We describe a broad resolution of the "Atlantic Paradox" concerning the seasonal and geographic distribution of tropical tropospheric ozone. We describe periods of significant maximum tropospheric O3 for Jan.-April, 1999, exploiting satellite estimates and SHADOZ (Southern Hemisphere Additional Ozonesondes). Trajectory analyses connecting sondes and Total Tropospheric Ozone (TTO)O3 maps suggest a complex influence from the Indian Ocean: beginning with mixed combustion sources, then low level transport, cumulonimbus venting, and finally high-level transport to the west, with possible mixing over Africa. For the Jan.- March highest column-O3 periods in the Atlantic, distinct sounding peaks trace to specific NO sources, especially lightning, while in the same episodes, recurring every 30 or 60 days, more diffuse buildups of Indian-to-Atlantic pollution make important contributions.

Convective lofting links Indian Ocean air pollution to paradoxical South Atlantic ozone maxima

NASA Technical Reports Server (NTRS)

Chatfield, R. B.; Guan, H.; Thompson, A. M.; Witte, J. C.

2005-01-01

We describe a broad resolution of the Atlantic Parado concerning the seasonal and geographic distribution, of tropical tropospheric ozone. We highlight periods of significant maximum tropospheric O3 for Jan.- April, 1999, exploiting satellite estimates and SHADOZ (Southern Hemisphere Additional Ozonesondes). Trajectory analyses connecting sondes and Total Tropospheric Ozone (TTO) maps suggest a complex influence from the Indian Ocean: beginning with mixed combustion sources, then low level transport, cumulonimbus venting, possible stratospheric input, and finally high-level transport to the west, with possible mixing over Africa. For the Jan.-March highest column-O3 periods in the Atlantic, distinct sounding peaks trace to specific NO sources, especially lightning, while in the same episodes, recurring every 20-50 days, more diffuse buildups of Indian-to-Atlantic pollution make important contributions.

Genetic differentiation and phylogeography of Mediterranean-North Eastern Atlantic blue shark (Prionace glauca, L. 1758) using mitochondrial DNA: panmixia or complex stock structure?

PubMed Central

Damalas, Dimitrios; Martinsohn, Jann; Zanzi, Antonella; Mariani, Stefano; Sperone, Emilio; Micarelli, Primo; Garibaldi, Fulvio; Megalofonou, Persefoni; Bargelloni, Luca; Franch, Rafaella; Macias, David; Prodöhl, Paulo; Fitzpatrick, Séan; Stagioni, Marco; Tinti, Fausto; Cariani, Alessia

2017-01-01

Background The blue shark (Prionace glauca, Linnaeus 1758) is one of the most abundant epipelagic shark inhabiting all the oceans except the poles, including the Mediterranean Sea, but its genetic structure has not been confirmed at basin and interoceanic distances. Past tagging programs in the Atlantic Ocean failed to find evidence of migration of blue sharks between the Mediterranean and the adjacent Atlantic, despite the extreme vagility of the species. Although the high rate of by-catch in the Mediterranean basin, to date no genetic study on Mediterranean blue shark was carried out, which constitutes a significant knowledge gap, considering that this population is classified as “Critically Endangered”, unlike its open-ocean counterpart. Methods Blue shark phylogeography and demography in the Mediterranean Sea and North-Eastern Atlantic Ocean were inferred using two mitochondrial genes (Cytb and control region) amplified from 207 and 170 individuals respectively, collected from six localities across the Mediterranean and two from the North-Eastern Atlantic. Results Although no obvious pattern of geographical differentiation was apparent from the haplotype network, Φst analyses indicated significant genetic structure among four geographical groups. Demographic analyses suggest that these populations have experienced a constant population expansion in the last 0.4–0.1 million of years. Discussion The weak, but significant, differences in Mediterranean and adjacent North-eastern Atlantic blue sharks revealed a complex phylogeographic structure, which appears to reject the assumption of panmixia across the study area, but also supports a certain degree of population connectivity across the Strait of Gibraltar, despite the lack of evidence of migratory movements observed by tagging data. Analyses of spatial genetic structure in relation to sex-ratio and size could indicate some level of sex/stage biased migratory behaviour. PMID:29230359

Genetic differentiation and phylogeography of Mediterranean-North Eastern Atlantic blue shark (Prionace glauca, L. 1758) using mitochondrial DNA: panmixia or complex stock structure?

PubMed

Leone, Agostino; Urso, Ilenia; Damalas, Dimitrios; Martinsohn, Jann; Zanzi, Antonella; Mariani, Stefano; Sperone, Emilio; Micarelli, Primo; Garibaldi, Fulvio; Megalofonou, Persefoni; Bargelloni, Luca; Franch, Rafaella; Macias, David; Prodöhl, Paulo; Fitzpatrick, Séan; Stagioni, Marco; Tinti, Fausto; Cariani, Alessia

2017-01-01

The blue shark ( Prionace glauca , Linnaeus 1758) is one of the most abundant epipelagic shark inhabiting all the oceans except the poles, including the Mediterranean Sea, but its genetic structure has not been confirmed at basin and interoceanic distances. Past tagging programs in the Atlantic Ocean failed to find evidence of migration of blue sharks between the Mediterranean and the adjacent Atlantic, despite the extreme vagility of the species. Although the high rate of by-catch in the Mediterranean basin, to date no genetic study on Mediterranean blue shark was carried out, which constitutes a significant knowledge gap, considering that this population is classified as "Critically Endangered", unlike its open-ocean counterpart. Blue shark phylogeography and demography in the Mediterranean Sea and North-Eastern Atlantic Ocean were inferred using two mitochondrial genes (Cytb and control region) amplified from 207 and 170 individuals respectively, collected from six localities across the Mediterranean and two from the North-Eastern Atlantic. Although no obvious pattern of geographical differentiation was apparent from the haplotype network, Φst analyses indicated significant genetic structure among four geographical groups. Demographic analyses suggest that these populations have experienced a constant population expansion in the last 0.4-0.1 million of years. The weak, but significant, differences in Mediterranean and adjacent North-eastern Atlantic blue sharks revealed a complex phylogeographic structure, which appears to reject the assumption of panmixia across the study area, but also supports a certain degree of population connectivity across the Strait of Gibraltar, despite the lack of evidence of migratory movements observed by tagging data. Analyses of spatial genetic structure in relation to sex-ratio and size could indicate some level of sex/stage biased migratory behaviour.

Hydroclimatology of Extreme Precipitation and Floods Originating from the North Atlantic Ocean

NASA Astrophysics Data System (ADS)

Nakamura, Jennifer

This study explores seasonal patterns and structures of moisture transport pathways from the North Atlantic Ocean and the Gulf of Mexico that lead to extreme large-scale precipitation and floods over land. Storm tracks, such as the tropical cyclone tracks in the Northern Atlantic Ocean, are an example of moisture transport pathways. In the first part, North Atlantic cyclone tracks are clustered by the moments to identify common traits in genesis locations, track shapes, intensities, life spans, landfalls, seasonal patterns, and trends. The clustering results of part one show the dynamical behavior differences of tropical cyclones born in different parts of the basin. Drawing on these conclusions, in the second part, statistical track segment model is developed for simulation of tracks to improve reliability of tropical cyclone risk probabilities. Moisture transport pathways from the North Atlantic Ocean are also explored though the specific regional flood dynamics of the U.S. Midwest and the United Kingdom in part three of the dissertation. Part I. Classifying North Atlantic Tropical Cyclones Tracks by Mass Moments. A new method for classifying tropical cyclones or similar features is introduced. The cyclone track is considered as an open spatial curve, with the wind speed or power information along the curve considered as a mass attribute. The first and second moments of the resulting object are computed and then used to classify the historical tracks using standard clustering algorithms. Mass moments allow the whole track shape, length and location to be incorporated into the clustering methodology. Tropical cyclones in the North Atlantic basin are clustered with K-means by mass moments producing an optimum of six clusters with differing genesis locations, track shapes, intensities, life spans, landfalls, seasonality, and trends. Even variables that are not directly clustered show distinct separation between clusters. A trend analysis confirms recent conclusions

Mechanisms underlying recent decadal changes in subpolar North Atlantic Ocean heat content

NASA Astrophysics Data System (ADS)

Piecuch, Christopher G.; Ponte, Rui M.; Little, Christopher M.; Buckley, Martha W.; Fukumori, Ichiro

2017-09-01

The subpolar North Atlantic (SPNA) is subject to strong decadal variability, with implications for surface climate and its predictability. In 2004-2005, SPNA decadal upper ocean and sea-surface temperature trends reversed from warming during 1994-2004 to cooling over 2005-2015. This recent decadal trend reversal in SPNA ocean heat content (OHC) is studied using a physically consistent, observationally constrained global ocean state estimate covering 1992-2015. The estimate's physical consistency facilitates quantitative causal attribution of ocean variations. Closed heat budget diagnostics reveal that the SPNA OHC trend reversal is the result of heat advection by midlatitude ocean circulation. Kinematic decompositions reveal that changes in the deep and intermediate vertical overturning circulation cannot account for the trend reversal, but rather ocean heat transports by horizontal gyre circulations render the primary contributions. The shift in horizontal gyre advection reflects anomalous circulation acting on the mean temperature gradients. Maximum covariance analysis (MCA) reveals strong covariation between the anomalous horizontal gyre circulation and variations in the local wind stress curl, suggestive of a Sverdrup response. Results have implications for decadal predictability.

Space Radar Image of North Atlantic Ocean

NASA Image and Video Library

1999-04-15

This is a radar image showing surface features on the open ocean in the northeast Atlantic Ocean. There is no land mass in this image. The purple line in the lower left of the image is the stern wake of a ship. The ship creating the wake is the bright white spot on the middle, left side of the image. The ship's wake is about 28 kilometers (17 miles) long in this image and investigators believe that is because the ship may be discharging oil. The oil makes the wake last longer and causes it to stand out in this radar image. A fairly sharp boundary or front extends from the lower left to the upper right corner of the image and separates two distinct water masses that have different temperatures. The different water temperature affects the wind patterns on the ocean. In this image, the light green area depicts rougher water with more wind, while the purple area is calmer water with less wind. The dark patches are smooth areas of low wind, probably related to clouds along the front, and the bright green patches are likely due to ice crystals in the clouds that scatter the radar waves. The overall "fuzzy" look of this image is caused by long ocean waves, also called swells. Ocean radar imagery allows the fine detail of ocean features and interactions to be seen, such as the wake, swell, ocean front and cloud effects, which can then be used to enhance the understanding of ocean dynamics on smaller and smaller scales. The image is centered at 42.8 degrees north latitude, 26.2 degrees west longitude and shows an area approximately 35 kilometers by 65 kilometers (22 by 40 miles). The colors in the image are assigned to different frequencies and polarizations of the radar as follows: red is L-band horizontally transmitted, horizontally received; green is C-band horizontally transmitted, horizontally received; blue is L-band vertically transmitted, vertically received. This image was acquired by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR

Deep-sea ostracods from the South Atlantic sector of the Southern ocean during the Last 370,000 years

USGS Publications Warehouse

Yasuhara, Moriaki; Cronin, T. M.; Hunt, G.; Hodell, D.A.

2009-01-01

We report changes of deep-sea ostracod fauna during the last 370,000 yr from the Ocean Drilling Program (ODP) Hole 704A in the South Atlantic sector of the Southern Ocean. The results show that faunal changes are coincident with glacial/interglacial-scale deep-water circulation changes, even though our dataset is relatively small and the waters are barren of ostracods until mid-MIS (Marine Isotope Stage) 5. Krithe and Poseidonamicus were dominant during the Holocene interglacial period and the latter part of MIS 5, when this site was under the influence of North Atlantic Deep Water (NADW). Conversely, Henryhowella and Legitimocythere were dominant during glacial periods, when this site was in the path of Circumpolar Deep Water (CPDW). Three new species (Aversovalva brandaoae, Poseidonamicus hisayoae, and Krithe mazziniae) are described herein. This is the first report of Quaternary glacial/interglacial scale deep-sea ostracod faunal changes in the Southern and South Atlantic Oceans, a key region for understanding Quaternary climate and deep-water circulation, although the paucity of Quaternary ostracods in this region necessitates further research. ?? 2009 The Paleontological Society.

Large fluctuations of dissolved oxygen in the Indian and Pacific oceans during Dansgaard-Oeschger oscillations caused by variations of North Atlantic Deep Water subduction

USGS Publications Warehouse

Schmittner, A.; Galbraith, E.D.; Hostetler, S.W.; Pedersen, Thomas F.; Zhang, R.

2007-01-01

Paleoclimate records from glacial Indian and Pacific oceans sediments document millennial-scale fluctuations of subsurface dissolved oxygen levels and denitrification coherent with North Atlantic temperature oscillations. Yet the mechanism of this teleconnection between the remote ocean basins remains elusive. Here we present model simulations of the oxygen and nitrogen cycles that explain how changes in deepwater subduction in the North Atlantic can cause large and synchronous variations of oxygen minimum zones, throughout the Northern Hemisphere of the Indian and Pacific oceans, consistent with the paleoclimate records. Cold periods in the North Atlantic are associated with reduced nutrient delivery to the upper Indo-Pacific oceans, thereby decreasing productivity. Reduced export production diminishes subsurface respiration of organic matter leading to higher oxygen concentrations and less denitrification. This effect of reduced oxygen consumption dominates at low latitudes. At high latitudes in the Southern Ocean and North Pacific, increased mixed layer depths and steepening of isopycnals improve ocean ventilation and oxygen supply to the subsurface. Atmospheric teleconnections through changes in wind-driven ocean circulation modify this basin-scale pattern regionally. These results suggest that changes in the Atlantic Ocean circulation, similar to those projected by climate models to possibly occur in the centuries to come because of anthropogenic climate warming, can have large effects on marine ecosystems and biogeochemical cycles even in remote areas. Copyright 2007 by the American Geophysical Union.

Large fluctuations of dissolved oxygen in the Indian and Pacific oceans during Dansgaard-Oeschger oscillations caused by variations of North Atlantic Deep Water subduction

NASA Astrophysics Data System (ADS)

Schmittner, Andreas; Galbraith, Eric D.; Hostetler, Steven W.; Pedersen, Thomas F.; Zhang, Rong

2007-09-01

Paleoclimate records from glacial Indian and Pacific oceans sediments document millennial-scale fluctuations of subsurface dissolved oxygen levels and denitrification coherent with North Atlantic temperature oscillations. Yet the mechanism of this teleconnection between the remote ocean basins remains elusive. Here we present model simulations of the oxygen and nitrogen cycles that explain how changes in deepwater subduction in the North Atlantic can cause large and synchronous variations of oxygen minimum zones throughout the Northern Hemisphere of the Indian and Pacific oceans, consistent with the paleoclimate records. Cold periods in the North Atlantic are associated with reduced nutrient delivery to the upper Indo-Pacific oceans, thereby decreasing productivity. Reduced export production diminishes subsurface respiration of organic matter leading to higher oxygen concentrations and less denitrification. This effect of reduced oxygen consumption dominates at low latitudes. At high latitudes in the Southern Ocean and North Pacific, increased mixed layer depths and steepening of isopycnals improve ocean ventilation and oxygen supply to the subsurface. Atmospheric teleconnections through changes in wind-driven ocean circulation modify this basin-scale pattern regionally. These results suggest that changes in the Atlantic Ocean circulation, similar to those projected by climate models to possibly occur in the centuries to come because of anthropogenic climate warming, can have large effects on marine ecosystems and biogeochemical cycles even in remote areas.

The Atlantic Multidecadal Variability in surface and deep ocean temperature and salinity fields from unperturbed climate simulations

NASA Astrophysics Data System (ADS)

Zanchettin, D.; Jungclaus, J. H.

2013-12-01

Large multidecadal fluctuations in basin-average sea-surface temperature (SST) are a known feature of observed, reconstructed and simulated variability in the North Atlantic Ocean. This phenomenon is often referred to as Multidecadal Atlantic Variability or AMV. Historical AMV fluctuations are associated with analog basin-scale changes in sea-surface salinity, so that warming corresponds to salinification and cooling to freshening [Polyakov et al., 2005]. The surface imprint of the AMV further corresponds to same-sign fluctuations in the shallow ocean and with opposite-sign fluctuations in the deep ocean for both temperature and salinity [Polyakov et al., 2005]. This out-of-phase behavior reflects the thermohaline overturning circulation shaping North Atlantic's low-frequency variability. Several processes contribute to the AMV, involving both ocean-atmosphere coupled processes and deep ocean circulation [e.g., Grossmann and Klotzbach, 2009]. In particular, recirculation in the North Atlantic subpolar gyre region of salinity anomalies from Arctic freshwater export may trigger multidecadal variability in the Atlantic meridional overturning circulation, and therefore may be part of the AMV [Jungclaus et al., 2005; Dima and Lohmann, 2007]. With this contribution, we aim to improve the physical interpretation of the AMV by investigating spatial and temporal patterns of temperature and salinity fields in the shallow and deep ocean. We focus on two unperturbed millennial-scale simulations performed with the Max Planck Institute Earth system model in its paleo (MPI-ESM-P) and low-resolution (MPI-ESM-LR) configurations, which provide reference control climates for assessments of pre-industrial and historical climate simulations. The two model configurations only differ for the presence, in MPI-ESM-LR, of an active module for dynamical vegetation. We use spatial-average indices and empirical orthogonal functions/principal components to track the horizontal and vertical

Identification of Holocene millennial-scale forcing in the North Atlantic area: Ocean/atmosphere contribution

NASA Astrophysics Data System (ADS)

Debret, M.; Masson-Delmotte, V.; Christophe, C.; de Vernal, A.; Massei, N.; Eynaud, F.; Nicolle, M.; Frank, N.; Mary, Y.; Magny, M.

2017-12-01

Millennial (1500-year) cycles were evidenced decades ago from the advance and retreat of glaciers but many subsequent studies failed to demonstrate the unequivocal character of such oscillation from paleoclimate time series. Hence, the identification of a persistent 1500 year periodicity remains controversial both for the last glacial episode and the Holocene. Applying wavelet analysis to Holocene climate records, we have identified synchronous millennial-scale oscillations which permit to establish a North Atlantic millennial variability index (NAV-Index), maximum at 5330 ± 245, 3560 ± 190, 1810 ± 160 cal years BP and minimum at 4430 ± 250, 2640 ± 225 and 970 ± 200 years before present. This NAV-index was compared with the millennial variability of cosmogenic 10Be isotope, a proxy of solar activity. Differences between the two sets of records suggest that an internal mechanism (Ocean/atmosphere) must be at the origin of the North Atlantic millennial scale variability. Our data document an increased coherence and magnitude of the North Atlantic millennial variability since 6000 cal. years BP, with a frequency of 1780 ± 240 years. During the early Holocene, deglacial meltwater fluxes had strong regional impact and the coupling between subpolar gyre migration and Atlantic meridional oceanic circulation observed since afterward seems to be related to the end of the Laurentide and Inuitian ice sheet meltwater discharge. Hence, we may conclude that the evolution of this millennial oscillation in the future will depend upon the Greenland stability or melting.

On the Flow of Atlantic Water Towards the Arctic Ocean; a Synergy Between Altimetry and Hydrography.

NASA Astrophysics Data System (ADS)

Chafik, L.; Nilsson, J.; Skagseth, O.; Lundberg, P.

2015-12-01

The Arctic climate is strongly influenced by the inflow of warm Atlantic water conveyed by the Norwegian Atlantic Slope Current (NwASC); the main heat conveyor into the Arctic Ocean. Based on sea surface height (SSH) data from altimetry, we develop a dynamical measure of the NwASC transport to diagnose its spatio-temporal variability. This supports a dynamical division of the NwASC into two flow regimes; the Svinøy Branch (SvB) in the Norwegian Sea, and the Fram Strait Branch (FSB) west of Spitsbergen. The SvB transport is well correlated with the SSH and atmospheric variability within the Nordic Seas, factors that also affect the inflow to the Barents Sea. In contrast, the FSB is regulated by regional atmospheric patterns around Svalbard and northern Barents Sea. We further relate anomalous flow events to temperature fluctuations of Atlantic water. A warm anomaly is found to propagate northwards, with a tendency to amplify enroute, after events of strong flow in the Norwegian Sea. A roughly 12-months delayed temperature signal is identified in the FSB. This suggests that hydrographic anomalies both upstream from the North Atlantic, and locally generated in the Norwegian Sea, are important for the oceanic heat and salt transport that eventually enters into the Arctic. We believe that the combination of the flow from altimetry and temperature fluctuations in the Nordic Seas can be used to qualitatively predict warm anomalies towards the Arctic Ocean, which could be a valuable addition to the forecast skill of the statistical Arctic sea-ice models.

Carbon and Neodymium Isotopic Fingerprints of Atlantic Deep Ocean Circulation During the Warm Pliocene

NASA Astrophysics Data System (ADS)

Riesselman, C. R.; Scher, H.; Robinson, M. M.; Dowsett, H. J.; Bell, D. B.

2012-12-01

Earth's future climate may resemble the mid-Piacenzian Age of the Pliocene, a time when global temperatures were sustained within the range predicted for the coming century. Surface and deep water temperature reconstructions and coupled ocean-atmosphere general circulation model simulations by the USGS PRISM (Pliocene Research Interpretation and Synoptic Mapping) Group identify a dramatic North Atlantic warm surface temperature anomaly in the mid-Piacenzian (3.264 - 3.025 Ma), accompanied by increased evaporation. The anomaly is detected in deep waters at 46°S, suggesting enhanced meridional overturning circulation and more southerly penetration of North Atlantic Deep Water (NADW) during the PRISM interval. However deep water temperature proxies are not diagnostic of water mass and some coupled model simulations predict transient decreases in NADW production in the 21st century, presenting a contrasting picture of future climate. We present a new multi-proxy investigation of Atlantic deep ocean circulation during the warm mid-Piacenzian, using δ13C of benthic foraminifera as a proxy for water mass age and the neodymium isotopic composition of fossil fish teeth (ɛNd) as a proxy for water mass source and mixing. This reconstruction utilizes both new and previously published data from DSDP and ODP cores along equatorial (Ceara Rise), southern mid-latitude (Walvis Ridge), and south Atlantic (Meteor Rise/Agulhas Ridge) depth transects. Additional end-member sites in the regions of modern north Atlantic and Southern Ocean deep water formation provide a Pliocene baseline for comparison. δ13C throughout the Atlantic basin is remarkably homogenous during the PRISM interval. δ13C values of Cibicidoides spp. and C. wuellerstorfi largely range between 0‰ and 1‰ at North Atlantic, shallow equatorial, southern mid-latitude, and south Atlantic sites with water depths from 2000-4700 m; both depth and latitudinal gradients are generally small (~0.3‰). However, equatorial

Helminth parasites of the oceanic horse mackerel Trachurus picturatus Bowdich 1825 (Pisces: Carangidae) from Madeira Island, Atlantic Ocean, Portugal.

PubMed

Costa, G; Melo-Moreira, E; Pinheiro de Carvalho, M A A

2012-09-01

The helminth parasite fauna of the oceanic horse mackerel Trachurus picturatus Bowdich 1825, caught off the Madeira Islands was composed of six different taxa. Prevalence and abundance of larval Anisakis sp. (Nematoda: Anisakidae) and Nybelinia lingualis (Trypanorhyncha: Tentaculariidae), the most common parasite taxa, were 24.3%, 0.9 and 37.9%, 0.7, respectively. Bolbosoma vasculosum (Acanthocephala: Polymorphidae) and the monogeneans Heteraxinoides atlanticus (Monogenea: Heteraxinidae) and Pseudaxine trachuri (Monogenea: Gastrocotylidae) were comparatively rare. The depauperate helminth fauna of the oceanic horse mackerel at Madeira compared to other geographical regions of the north-eastern Atlantic, namely the Azores banks and the West African coast, may be attributed to the paucity of nutrients off oceanic islands and to a low density of the fish population.

Oceanic Situational Awareness Over the Western Atlantic Track Routing System

NASA Technical Reports Server (NTRS)

Welch, Bryan; Greenfeld, Israel

2005-01-01

Air traffic control (ATC) mandated, aircraft separations over the oceans impose a limitation on traffic capacity for a given corridor, given the projected traffic growth over the Western Atlantic Track Routing System (WATRS). The separations result from a lack of acceptable situational awareness over oceans where radar position updates are not available. This study considers the use of Automatic Dependent Surveillance (ADS) data transmitted over a commercial satellite communications system as an approach to provide ATC with the needed situational awareness and thusly allow for reduced aircraft separations. This study uses Federal Aviation Administration data from a single day for the WATRS corridor to analyze traffic loading to be used as a benchmark against which to compare several approaches for coordinating data transmissions from the aircraft to the satellites.

Saharan Dust Fertilizing Atlantic Ocean and Amazon Rainforest via Long-range Transport and Deposition: A Perspective from Multiyear Satellite Measurements

NASA Astrophysics Data System (ADS)

Yu, H.; Chin, M.; Yuan, T.; Bian, H.; Remer, L. A.; Prospero, J. M.; Omar, A. H.; Winker, D. M.; Yang, Y.; Zhang, Y.; Zhang, Z.; Zhao, C.

2015-12-01

Massive dust emitted from Sahara desert is carried by trade winds across the tropical Atlantic Ocean, reaching the Amazon Rainforest and Caribbean Sea. Airborne dust degrades air quality and interacts with radiation and clouds. Dust falling to land and ocean adds essential nutrients that could increase the productivity of terrestrial and aquatic ecosystems and modulate the biogeochemical cycles and climate. The resultant climate change will feed back on the production of dust in Sahara desert and its subsequent transport and deposition. Understanding the connections among the remote ecosystems requires an accurate quantification of dust transport and deposition flux on large spatial and temporal scales, in which satellite remote sensing can play an important role. We provide the first multiyear satellite-based estimates of altitude-resolved across-Atlantic dust transport and deposition based on eight-year (2007-2014) record of aerosol three-dimensional distributions from the CALIPSO lidar. On a basis of the 8-year average, 179 Tg (million tons) of dust leaves the coast of North Africa and is transported across Atlantic Ocean, of which 102, 20, and 28 Tg of dust is deposited into the tropical Atlantic Ocean, Caribbean Sea, and Amazon Rainforest, respectively. The dust deposition adds 4.3 Tg of iron and 0.1 Tg of phosphorus to the tropical Atlantic Ocean and Caribbean Sea where the productivity of marine ecosystem depends on the availability of these nutrients. The 28 Tg of dust provides about 0.022 Tg of phosphorus to Amazon Rainforest yearly that replenishes the leak of this plant-essential nutrient by rains and flooding, suggesting an important role of Saharan dust in maintaining the productivity of Amazon rainforest on timescales of decades or centuries. We will also discuss seasonal and interannual variations of the dust transport and deposition, and comparisons of the CALIOP-based estimates with model simulations.

First record of a digenean from invasive lionfish, Pterois cf. volitans, (Scorpaeniformes: Scorpaenidae) in the northwestern Atlantic Ocean.

PubMed

Bullard, S A; Barse, A M; Curran, S S; Morris, J A

2011-10-01

Adults of Lecithochirium floridense (Digenea: Hemiuridae) parasitized the stomach in each of 22 necropsied lionfish, Pterois cf. volitans (Scorpaeniformes: Scorpaenidae) (prevalence  =  100%, mean intensity  =  11), captured in the northwestern Atlantic Ocean off Beaufort, North Carolina (34°14.83'N, 76°35.25'W). This is the first report of a digenean from the invasive lionfish and that of L. floridense from a species of Pterois. The leech specimen previously identified as Myzobdella lugubris from P. volitans in the northwestern Atlantic Ocean is re-identified as Trachelobdella lubrica based on a study of the original voucher specimen.

Spectrophotometric Measurements of the Carbonate Ion Concentration: Aragonite Saturation States in the Mediterranean Sea and Atlantic Ocean.

PubMed

Fajar, Noelia M; García-Ibáñez, Maribel I; SanLeón-Bartolomé, Henar; Álvarez, Marta; Pérez, Fiz F

2015-10-06

Measurements of ocean pH, alkalinity, and carbonate ion concentrations ([CO3(2-)]) during three cruises in the Atlantic Ocean and one in the Mediterranean Sea were used to assess the reliability of the recent spectrophotometric [CO3(2-)] methodology and to determine aragonite saturation states. Measurements of [CO3(2-)] along the Atlantic Ocean showed high consistency with the [CO3(2-)] values calculated from pH and alkalinity, with negligible biases (0.4 ± 3.4 μmol·kg(-1)). In the warm, salty, high alkalinity and high pH Mediterranean waters, the spectrophotometric [CO3(2-)] methodology underestimates the measured [CO3(2-)] (4.0 ± 5.0 μmol·kg(-1)), with anomalies positively correlated to salinity. These waters also exhibited high in situ [CO3(2-)] compared to the expected aragonite saturation. The very high buffering capacity allows the Mediterranean Sea waters to remain over the saturation level of aragonite for long periods of time. Conversely, the relatively thick layer of undersaturated waters between 500 and 1000 m depths in the Tropical Atlantic is expected to progress to even more negative undersaturation values. Moreover, the northern North Atlantic presents [CO3(2-)] slightly above the level of aragonite saturation, and the expected anthropogenic acidification could result in reductions of the aragonite saturation levels during future decades, acting as a stressor for the large population of cold-water-coral communities.

Coralline algal Barium as indicator for 20th century northwestern North Atlantic surface ocean freshwater variability

PubMed Central

Hetzinger, S.; Halfar, J.; Zack, T.; Mecking, J. V.; Kunz, B. E.; Jacob, D. E.; Adey, W. H.

2013-01-01

During the past decades climate and freshwater dynamics in the northwestern North Atlantic have undergone major changes. Large-scale freshening episodes, related to polar freshwater pulses, have had a strong influence on ocean variability in this climatically important region. However, little is known about variability before 1950, mainly due to the lack of long-term high-resolution marine proxy archives. Here we present the first multidecadal-length records of annually resolved Ba/Ca variations from Northwest Atlantic coralline algae. We observe positive relationships between algal Ba/Ca ratios from two Newfoundland sites and salinity observations back to 1950. Both records capture episodical multi-year freshening events during the 20th century. Variability in algal Ba/Ca is sensitive to freshwater-induced changes in upper ocean stratification, which affect the transport of cold, Ba-enriched deep waters onto the shelf (highly stratified equals less Ba/Ca). Algal Ba/Ca ratios therefore may serve as a new resource for reconstructing past surface ocean freshwater changes. PMID:23636135

Coralline algal barium as indicator for 20th century northwestern North Atlantic surface ocean freshwater variability.

PubMed

Hetzinger, S; Halfar, J; Zack, T; Mecking, J V; Kunz, B E; Jacob, D E; Adey, W H

2013-01-01

During the past decades climate and freshwater dynamics in the northwestern North Atlantic have undergone major changes. Large-scale freshening episodes, related to polar freshwater pulses, have had a strong influence on ocean variability in this climatically important region. However, little is known about variability before 1950, mainly due to the lack of long-term high-resolution marine proxy archives. Here we present the first multidecadal-length records of annually resolved Ba/Ca variations from Northwest Atlantic coralline algae. We observe positive relationships between algal Ba/Ca ratios from two Newfoundland sites and salinity observations back to 1950. Both records capture episodical multi-year freshening events during the 20th century. Variability in algal Ba/Ca is sensitive to freshwater-induced changes in upper ocean stratification, which affect the transport of cold, Ba-enriched deep waters onto the shelf (highly stratified equals less Ba/Ca). Algal Ba/Ca ratios therefore may serve as a new resource for reconstructing past surface ocean freshwater changes.

Plastic ingestion in oceanic-stage loggerhead sea turtles (Caretta caretta) off the North Atlantic subtropical gyre.

PubMed

Pham, Christopher K; Rodríguez, Yasmina; Dauphin, Axelle; Carriço, Rita; Frias, João P G L; Vandeperre, Frederic; Otero, Vanessa; Santos, Marco R; Martins, Helen R; Bolten, Alan B; Bjorndal, Karen A

2017-08-15

Juvenile oceanic-stage sea turtles are particularly vulnerable to the increasing quantity of plastic coming into the oceans. In this study, we analysed the gastrointestinal tracts of 24 juvenile oceanic-stage loggerheads (Caretta caretta) collected off the North Atlantic subtropical gyre, in the Azores region, a key feeding ground for juvenile loggerheads. Twenty individuals were found to have ingested marine debris (83%), composed exclusively of plastic items (primarily polyethylene and polypropylene) identified by μ-Fourier Transform Infrared Spectroscopy. Large microplastics (1-5mm) represented 25% of the total number of debris and were found in 58% of the individuals sampled. Average number of items was 15.83±6.09 (±SE) per individual, corresponding to a mean dry mass of 1.07±0.41g. The results of this study demonstrate that plastic pollution acts as another stressor for this critical life stage of loggerhead turtles in the North Atlantic. Copyright © 2017 Elsevier Ltd. All rights reserved.

Subduction in an Eddy-Resolving State Estimate of the Northeast Atlantic Ocean

NASA Technical Reports Server (NTRS)

Gebbie, Geoffrey

2004-01-01

Are eddies an important contributor to subduction in the eastern subtropical gyre? Here, an adjoint model is used to combine a regional, eddy-resolving numerical model with observations to produce a state estimate of the ocean circulation. The estimate is a synthesis of a variety of in- situ observations from the Subduction Experiment, TOPEX/POSEIDON altimetry, and the MTI General Circulation Model. The adjoint method is successful because the Northeast Atlantic Ocean is only weakly nonlinear. The state estimate provides a physically-interpretable, eddy-resolving information source to diagnose subduction. Estimates of eddy subduction for the eastern subtropical gyre of the North Atlantic are larger than previously calculated from parameterizations in coarse-resolution models. Furthermore, eddy subduction rates have typical magnitudes of 15% of the total subduction rate. Eddies contribute as much as 1 Sverdrup to water-mass transformation, and hence subduction, in the North Equatorial Current and the Azores Current. The findings of this thesis imply that the inability to resolve or accurately parameterize eddy subduction in climate models would lead to an accumulation of error in the structure of the main thermocline, even in the relatively-quiescent eastern subtropical gyre.

Explanations for Temperature Increases in the Northern and Southern Atlantic Ocean are Proposed

NASA Astrophysics Data System (ADS)

Cimorelli, S. A.

2012-04-01

Primarily, consider some background hypotheses in the first paragraph: Three Types of mechanisms for Stellar Origin, Formation and Evolution are hypothesized. The first type (A) is well known; whereas, the other two (B&C) are new and proposed herein. The type A process, the presently universally accepted process, consists of the three phases of gravitation, followed by accretion, followed by fragmentation. In a Type B process, a star originates as an expanded, modified, category 3 Black Hole (BH) [1], with none or little help from gravitation/accretion, that begins to radiate, and continues to grow into a star. In a Type C process, a star would originate from a combination of the mechanisms described above for Type B and A. This mechanism, Type C, is perhaps the most common type. This type starts as an expanded, modified, category 3 BH inside of a gas and dust cloud. This then serves as the nucleus that starts the subsequent gravitation/accretion process; however, it greatly accelerates the accretion/formation process as in a standard Type A process. This mechanism could then explain how some super-cluster complexes, which have been estimated would take 40 to 60 billion years to form, can occur in a universe of a much younger age, i.e. 13.7 billion years. Also, consider that the ratio of the 'surface area to volume' is greater in a relatively smaller sphere; which would cause that smaller body of limited energy to cool off'/down, faster; however to continue to grow. A suggested sequence to explain why the Northern (South Greenland) and Southern Regions of the Atlantic Ocean are getting warmer is proposed: As the earth grows, two things occur, among others [1]. It is hypothesized the earth is expanding, circumferentially, about 3 cm per year at the equator (1 cm in the Atlantic, and 2 cm in the Pacific), rather than just 1 cm at the center of the Atlantic, as is commonly accepted. The earth may be expanding at an even greater rate, longitudinally (north and south

Stronger Ocean Meridinal Heat Transport with a Weaker Atlantic Meridional Overturning Circulation?

NASA Astrophysics Data System (ADS)

Sevellec, F.; Fedorov, A. V.

2014-12-01

It is typically assumed that oceanic heat transport is well and positively correlated with the Atlantic Meridional Ocean Circulation (AMOC). In numerical "water-hosing" experiments, for example, imposing an anomalous freshwater flux in the northern hemisphere leads to a slow-down of the AMOC and a corresponding reduction of the northward heat transport. Here, we study the sensitivity of the heat transport to surface freshwater fluxes using a generalized stability analysis and find that, while the direct relationship between the AMOC and heat transport holds on shorter time scales, it completely reverses on timescales longer than ~500 yr. That is, a reduction in the AMOC volume transport can actually lead to a stronger heat transport on those long timescales, which results from the gradual increase in ocean thermal stratification. We discuss the implications of these results for the problem of steady state (statistically equilibrium) in ocean and climate GCM as well as various paleoclimate problems such as millennial climate variability and the maintenance of equable climate states.

Projected changes to South Atlantic boundary currents and confluence region in the CMIP5 models: the role of wind and deep ocean changes

NASA Astrophysics Data System (ADS)

Pontes, G. M.; Gupta, A. Sen; Taschetto, A. S.

2016-09-01

The South Atlantic (SA) circulation plays an important role in the oceanic teleconnections from the Indian, Pacific and Southern oceans to the North Atlantic, with inter-hemispheric exchanges of heat and salt. Here, we show that the large-scale features of the SA circulation are projected to change significantly under ‘business as usual’ greenhouse gas increases. Based on 19 models from the Coupled Model Intercomparison Project phase 5 there is a projected weakening in the upper ocean interior transport (<1000 m) between 15° and ˜32°S, largely related to a weakening of the wind stress curl over this region. The reduction in ocean interior circulation is largely compensated by a decrease in the net deep southward ocean transport (>1000 m), mainly related to a decrease in the North Atlantic deep water transport. Between 30° and 40°S, there is a consistent projected intensification in the Brazil current strength of about 40% (30%-58% interquartile range) primarily compensated by an intensification of the upper interior circulation across the Indo-Atlantic basin. The Brazil-Malvinas confluence is projected to shift southwards, driven by a weakening of the Malvinas current. Such a change could have important implications for the distribution of marine species in the southwestern SA in the future.

Retrospective analysis of seasonal ocean growth rates of two sea winter Atlantic Salmon in eastern Maine using historic scales

USGS Publications Warehouse

Izzo, Lisa K.; Zydlewski, Joseph D.

2017-01-01

Substantial declines of anadromous Atlantic Salmon Salmo salar have occurred throughout its range, with many populations at the southern extent of the distribution currently extirpated or endangered. While both one sea winter (1SW) and two sea winter (2SW) spawner numbers for the North American stocks have declined since the 1950s, the decline has been most severe in 2SW spawners. The first months at sea are considered a period of high mortality. However, early ocean mortality alone cannot explain the more pronounced decline of 2SW spawners, suggesting that the second year at sea may be more critical than previously thought. Atlantic Salmon scales collected by anglers and the state agency from 1946 to 2013 from five rivers in eastern Maine were used to estimate smolt age and ocean age of returning adults. Additionally, seasonal growth rates of maiden 2SW spawners were estimated using intercirculi measurements and linear back-calculation methods. Generalized linear mixed models (Gaussian family, log link function) were used to investigate the influence of average sea surface temperature, accumulated thermal units, the Atlantic Multidecadal Oscillation (AMO) and North Atlantic Oscillation indices, smolt age, smolt length, postsmolt growth, and river of origin on growth rate during the oceanic migration of North American Atlantic Salmon. Results suggest that different factors influence salmon growth throughout their oceanic migration, and previous growth can be a strong predictor of future size. Growth was negatively impacted by the phase of the AMO, which has been linked to salmon abundance trends, in early spring following the postsmolt period. This is likely when the 1SW and 2SW stock components separate, and our results suggest that this period may be of interest in future work examining the disproportionate decline in 2SW spawners.

Population genetic structure in Atlantic and Pacific Ocean common murres (Uria aalge): Natural replicate tests of post-Pleistocene evolution

USGS Publications Warehouse

Morris-Pocock, J. A.; Taylor, S.A.; Birt, T.P.; Damus, M.; Piatt, John F.; Warheit, K.I.; Friesen, Vicki L.

2008-01-01

Understanding the factors that influence population differentiation in temperate taxa can be difficult because the signatures of both historic and contemporary demographics are often reflected in population genetic patterns. Fortunately, analyses based on coalescent theory can help untangle the relative influence of these historic and contemporary factors. Common murres (Uria aalge) are vagile seabirds that breed in the boreal and low arctic waters of the Northern Hemisphere. Previous analyses revealed that Atlantic and Pacific populations are genetically distinct; however, less is known about population genetic structure within ocean basins. We employed the mitochondrial control region, four microsatellite loci and four intron loci to investigate population genetic structure throughout the range of common murres. As in previous studies, we found that Atlantic and Pacific populations diverged during the Pleistocene and do not currently exchange migrants. Therefore, Atlantic and Pacific murre populations can be used as natural replicates to test mechanisms of population differentiation. While we found little population genetic structure within the Pacific, we detected significant east-west structuring among Atlantic colonies. The degree that population genetic structure reflected contemporary population demographics also differed between ocean basins. Specifically, while the low levels of population differentiation in the Pacific are at least partially due to high levels of contemporary gene flow, the east-west structuring of populations within the Atlantic appears to be the result of historic fragmentation of populations rather than restricted contemporary gene flow. The contrasting results in the Atlantic and Pacific Oceans highlight the necessity of carefully considering multilocus nonequilibrium population genetic approaches when reconstructing the demographic history of temperate Northern Hemisphere taxa. ?? 2008 The Authors.

Invasive species in the Northeastern and Southwestern Atlantic Ocean: A review.

PubMed

Castro, Maria Cecilia T de; Fileman, Timothy W; Hall-Spencer, Jason M

2017-03-15

The spread of non-native species has been a subject of increasing concern since the 1980s when human-mediated transportation, mainly related to ships' ballast water, was recognized as a major vector for species transportation and spread, although records of non-native species go back as far as 16th Century. Ever increasing world trade and the resulting rise in shipping have highlighted the issue, demanding a response from the international community to the threat of non-native marine species. In the present study, we searched for available literature and databases on shipping and invasive species in the North-eastern (NE) and South-western (SW) Atlantic Ocean and assess the risk represented by the shipping trade between these two regions. There are reports of 44 species associated with high impacts for the NE Atlantic and 15 for the SW Atlantic, although this may be an underestimate. Vectors most cited are ballast water and biofouling for both regions while aquaculture has also been a very significant pathway of introduction and spread of invasive species in the NE Atlantic. Although the two regions have significant shipping traffic, no exchange of invasive species could be directly associated to the shipping between the two regions. However, it seems prudent to bring the exchange of ballast water between the two regions under control as soon as possible. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Atlantic Meridional Transect: Spatially Extensive Calibration and Validation of Optical Properties and Remotely Sensed Measurements of Ocean Colour

NASA Technical Reports Server (NTRS)

Aiken, James; Hooker, Stanford

1997-01-01

Twice a year, the Royal Research Ship (RRS) James Clark Ross (JCR) steams a meridional transect of the atlantic Ocean between Grimsly (UK) and Stanley (Falkland Islands) with a port call in Montevideo (Uruguay), as part of the annual research activities of the British Antarctic Survey (BAS). In September, the JCR sails from the UK, and the following April it makes the return trip. The ship is operated by the BAS for the Natural Environment Research Council (NERC). The Atlantic Meridional Transect (AMT) Program exploits the passage of the JCR from approximately 50 deg. N to 50 deg. S with a primary objective to investigate physical and biological processes, as well as to measure the mesi-to-basin-scale bio-optical properties of the atlantic Ocean. The calibration and validation of remotely sensed observations of ocean colour is an inherent objective of these studies: first, by relating in situ measurements of water leaving radiance to satellite measurement, and second, by measuring the bio-optically active constituents of the water.

Tectono-Magmatic Evolution of the South Atlantic Continental Margins with Respect to Opening of the Ocean

NASA Astrophysics Data System (ADS)

Melankholina, E. N.; Sushchevskaya, N. M.

2018-03-01

The history of the opening of the South Atlantic in Early Cretaceous time is considered. It is shown that the determining role for continental breakup preparation has been played by tectono-magmatic events within the limits of the distal margins that developed above the plume head. The formation of the Rio Grande Rise-Walvis Ridge volcanic system along the trace of the hot spot is considered. The magmatism in the South Atlantic margins, its sources, and changes in composition during the evolution are described. On the basis of petrogeochemical data, the peculiarities of rocks with a continental signature are shown. Based on Pb-Sr-Nd isotopic studies, it is found that the manifestations of magmatism in the proximal margins had features of enriched components related to the EM I and EM II sources, sometimes with certain participation of the HIMU source. Within the limits of the Walvis Ridge, as magmatism expanded to the newly formed oceanic crust, the participation of depleted asthenospheric mantle became larger in the composition of magmas. The role played by the Tristan plume in magma generation is discussed: it is the most considered as the heat source that determined the melting of the ancient enriched lithosphere. The specifics of the tectono-magmatic evolution of the South Atlantic is pointed out: the origination during spreading of a number of hot spots above the periphery of the African superplume. The diachronous character of the opening of the ocean is considered in the context of northward progradation of the breakup line and its connection with the northern branch of the Atlantic Ocean in the Mid-Cretaceous.

Regional and inter-annual variability in Atlantic zooplankton en route to the Arctic Ocean: potential effects of multi-path Atlantic water advection through Fram Strait and the Barents Sea

NASA Astrophysics Data System (ADS)

Kwasniewski, Slawomir; Gluchowska, Marta; Trudnowska, Emilia; Ormanczyk, Mateusz; Walczowski, Waldemar; Beszczynska-Moeller, Agnieszka

2016-04-01

The Arctic is among the regions where the climate change effects on ecosystem will be the most rapid and consequential, with Arctic amplification recognized as an integral part of the process. Great part of the changes are forced by advection of warm waters from the North Atlantic and the expected modifications of Arctic marine ecosystem will be induced not only by changing environmental conditions but also as a result of introducing Atlantic biota. Thus, the knowledge of physical and biological heterogeneity of Atlantic inflow is requisite for understanding the effects of climate change on biological diversity and ecosystem functioning in the Arctic. The complex and variable two-branched structure of the Atlantic Water flow via Fram Strait and the Barents Sea most likely has a strong influence on the ocean biology in these regions, especially in the pelagic realm. Zooplankton are key components of marine ecosystems which form essential links between primary producers and grazer/predator consumers, thus they are important for functioning of the biological carbon pump. Changes in zooplankton distribution and abundance may have cascading effects on ecosystem functioning, with regulatory effects on climate. Based on data collected in summers of 2012-2014, within the scope of the Polish-Norwegian PAVE research project, we investigate zooplankton distribution, abundance and selected structural characteristics of communities, in relation to water mass properties in the Atlantic Water complex flow to the Arctic Ocean. The main questions addressed here are: what are the differences in zooplankton patterns between the Fram Strait and Barents Sea branches, and how does the inter-annual variability of Atlantic Water advection relate to changes in zooplankton? The results of the investigation are precondition for foreseeing changes in the pelagic realm in the Arctic Ocean and are necessary for constructing and tuning plankton components of ecosystem models.

Dynamical attribution of oceanic prediction uncertainty in the North Atlantic: application to the design of optimal monitoring systems

NASA Astrophysics Data System (ADS)

Sévellec, Florian; Dijkstra, Henk A.; Drijfhout, Sybren S.; Germe, Agathe

2017-11-01

In this study, the relation between two approaches to assess the ocean predictability on interannual to decadal time scales is investigated. The first pragmatic approach consists of sampling the initial condition uncertainty and assess the predictability through the divergence of this ensemble in time. The second approach is provided by a theoretical framework to determine error growth by estimating optimal linear growing modes. In this paper, it is shown that under the assumption of linearized dynamics and normal distributions of the uncertainty, the exact quantitative spread of ensemble can be determined from the theoretical framework. This spread is at least an order of magnitude less expensive to compute than the approximate solution given by the pragmatic approach. This result is applied to a state-of-the-art Ocean General Circulation Model to assess the predictability in the North Atlantic of four typical oceanic metrics: the strength of the Atlantic Meridional Overturning Circulation (AMOC), the intensity of its heat transport, the two-dimensional spatially-averaged Sea Surface Temperature (SST) over the North Atlantic, and the three-dimensional spatially-averaged temperature in the North Atlantic. For all tested metrics, except for SST, ˜ 75% of the total uncertainty on interannual time scales can be attributed to oceanic initial condition uncertainty rather than atmospheric stochastic forcing. The theoretical method also provide the sensitivity pattern to the initial condition uncertainty, allowing for targeted measurements to improve the skill of the prediction. It is suggested that a relatively small fleet of several autonomous underwater vehicles can reduce the uncertainty in AMOC strength prediction by 70% for 1-5 years lead times.

75 FR 56467 - Safety Zone; Ocean City Beachfront Air Show, Ocean City, NJ

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-16

...-AA00 Safety Zone; Ocean City Beachfront Air Show, Ocean City, NJ AGENCY: Coast Guard, DHS. ACTION... Atlantic Ocean, Ocean City, NJ. The temporary safety zone will restrict vessel traffic from a portion of the Atlantic Ocean during the Ocean City Beachfront Air Show, which is an aerial demonstration to be...

First occurrence of the lined seahorse Hippocampus erectus in the eastern Atlantic Ocean.

PubMed

Woodall, L C; Koldewey, H J; Santos, S V; Shaw, P W

2009-10-01

A seahorse specimen from Banco Açores (Azores Archipelago) was identified using morphological and molecular genetic data as Hippocampus erectus. This specimen represents the first record of H. erectus in the eastern Atlantic Ocean, well outside its reported range, and may provide evidence of long-distance translocation in what are assumed to be relatively sedentary fish.

Asynchronous North Atlantic iceberg discharges during the last glacial period explained through ocean circulation changes

NASA Astrophysics Data System (ADS)

Montoya, M.; Banderas, R.; Alvarez-Solas, J.; Robinson, A.

2017-12-01

Heinrich events (HEs) are episodes of increased ice-rafted debris (IRD) deposition in the North Atlantic Ocean that took place during stadials of the last glacial period, and are interpreted as massive iceberg discharges from the Laurentide Ice Sheet (LIS). IRD originating from the Fennoscandian ice sheet (FIS) accompany HEs during stadials, but enhanced calving has also been reported, however, during interstadials. While a number of mechanisms have been proposed to explain HEs involving the LIS, the role of the FIS during these events has not received much attention from a modeling perspective. Thus, a consistent explanation for the asynchronous occurrence of enhanced IRD throughout the North Atlantic is lacking. Here we investigate the response of the FIS to millennial-scale climate variability during the last glacial period. We use a hybrid three-dimensional thermomechanical ice-sheet model forced offline through a novel perturbative approach accounting for a more realistic treatment of millennial-scale climatic variability, including both the atmospheric and the oceanic components. Our results show that the FIS responds with enhanced iceberg discharges in phase with interstadial warmings in the North Atlantic. Separating the atmospheric and oceanic effects demonstrates the major role of the ocean in controlling the dynamics of the FIS on millennial timescales. While the atmospheric forcing alone is only able to produce modest iceberg discharges (< 0.02 Sv), the warmer oceanic surface waters lead to much higher rates of iceberg surges (ca. 0.1 Sv) as a result of relatively high basal melting rates within the margins of the ice sheet through the reactivation of ice streams in the northeastern (NE) part of the ice sheet. Together with previous work our results provide a consistent explanation for the asynchronous response of the LIS and the FIS to glacial abrupt climate changes. Finally, they support the notion that the FIS is a likely candidate to produce iceberg

How do local and remote processes affect the distribution of iron in the Atlantic Ocean?

NASA Astrophysics Data System (ADS)

Tagliabue, A.; Boyd, P.; Rijkenberg, M. J. A.; Williams, R. G.

2016-02-01

Iron (Fe) plays an important role in governing the magnitudes and patterns of primary productivity, nitrogen fixation and phytoplankton community composition across the Atlantic Ocean. Variations in the supply of Fe to surface waters across the mixed layer interface, over seasonal to annual to decadal scales, are underpinned by it's vertical profile. Traditionally, nutrient profiles are understood in terms of surface depletion and subsurface regeneration, but for Fe this is more complicated due to the role of scavenging and organic complexation by ligands, as well as subsurface sources. This means that the Fe profile may be controlled locally, by sinking, regeneration and scavenging or remotely, by the upstream conditions of subducted water masses. Subduction drives the transfer of Fe across the interface between winter mixed layer and the ocean interior, but has received little attention thus far. Via the subduction of watermasses with distinct biogeochemical signatures to low latitudes, remote processes can regulate the Atlantic Ocean Fe distribution at local scales. Specifically, the formation of mode waters with excess Fe binding ligands (positive L*) enable these waters to stabilise any Fe flux from regeneration that would otherwise be lost by scavenging. The pattern of mode water ventilation then highlights those regions of the ocean where local processes are able to influence the Fe profile. Local process that augment L*, such as the production of ligands during particle regeneration, can also interact with the larger scale ventilation signature but do not alter the main trends. By applying our framework to recent GEOTRACES datasets over the Atlantic Ocean we are able to highlight regions where the Fe profile is forced locally or remotely, thereby providing an important process-based constraint on the biogeochemical models we rely on for future projections. Furthermore, we are able to appraise how the varying influence of local and remote processes drives

Ecological Condition of Coastal Ocean Waters Along the U.S. Mid-Atlantic Bight: 2006

EPA Science Inventory

This report presents the results of an assessment of ecological condition in coastal-ocean waters of the U.S. mid-Atlantic Bight (MAB), along the U.S. continental shelf from Cape Cod, MA and Nantucket Shoals to the northeast to Cape Hatteras to the south, based on sampling conduc...

77 FR 63722 - Special Local Regulations; Palm Beach World Championship, Atlantic Ocean; Jupiter, FL

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-17

...-AA08 Special Local Regulations; Palm Beach World Championship, Atlantic Ocean; Jupiter, FL AGENCY... offshore of Jupiter, Florida during the Palm Beach World Championship, a high speed power boat race. The Palm Beach World Championship is scheduled to take place on Friday, October 19, and Sunday, October 21...

Downscaling ocean conditions with application to the Gulf of Maine, Scotian Shelf and adjacent deep ocean

NASA Astrophysics Data System (ADS)

Katavouta, Anna; Thompson, Keith

2017-04-01

A high resolution regional model (1/36 degree) of the Gulf of Maine, Scotian Shelf and adjacent deep ocean (GoMSS) is developed to downscale ocean conditions from an existing global operational system. First, predictions from the regional GoMSS model in a one-way nesting set up are evaluated using observations from multiple sources including satellite-borne sensors of surface temperature and sea level, CTDs, Argo floats and moored current meters. It is shown that on the shelf, the regional model predicts more realistic fields than the global system because it has higher resolution and includes tides that are absent from the global system. However, in deep water the regional model misplaces deep ocean eddies and meanders associated with the Gulf Stream. This is because of unrealistic internally generated variability (associated with the one-way nesting set up) that leads to decoupling of the regional model from the global system in the deep water. To overcome this problem, the large scales (length scales > 90 km) of the regional model are spectrally nudged towards the global system fields. This leads to more realistic predictions off the shelf. Wavenumber spectra show that even though spectral nudging constrains the large scales, it does not suppress the variability on small scales; on the contrary, it favours the formation of eddies with length scales below the cut-off wavelength of the spectral nudging.

Carbonate dissolution in the South Atlantic Ocean: evidence from ultrastructure breakdown in Globigerina bulloides

NASA Astrophysics Data System (ADS)

Dittert, Nicolas; Henrich, Rüdiger

2000-04-01

Ultrastructure dissolution susceptibility of the planktic foraminifer Globigerina bulloides, carbonate ion content of the water column, calcium carbonate content of the sediment surface, and carbonate/carbon weight percentage ratio derived from sediment surface samples were investigated in order to reconstruct the position of the calcite saturation horizon, the sedimentary calcite lysocline, and the calcium carbonate compensation depth (CCD) in the modern South Atlantic Ocean. Carbonate ion data from the water column refer to the GEOSECS locations 48, 103, and 109 and calcium carbonate data come from 19 GeoB sediment surface samples of 4 transects into the Brazil, the Guinea, and the Cape Basins. We present a new (paleo-) oceanographic tool, namely the Globigerina bulloides dissolution index (BDX). Further, we give evidence (a) for progressive G. bulloides ultrastructural breakdown with increasing carbonate dissolution even above the lysocline; (b) for a sharp BDX increase at the sedimentary lysocline; and (c) for the total absence of this species at the CCD. BDX puts us in the position to distinguish the upper open ocean and the upwelling influenced continental margin above from the deep ocean below the sedimentary lysocline. Carbonate ion data from water column samples, calcite weight percentage data from surface sediment samples, and carbonate/carbon weight percentage ratio appear to be good proxies to confirm BDX. As shown by BDX both the calcite saturation horizon (in the water column) and the sedimentary lysocline (at the sediment-water interface) mark the boundary between the carbonate ion undersaturated and highly corrosive Antarctic Bottom Water and the carbonate ion saturated North Atlantic Deep Water (NADW) of the modern South Atlantic.

Ocean science: Radiocarbon variability in the western North Atlantic during the last deglaciation

USGS Publications Warehouse

Robinson, L.F.; Adkins, J.F.; Keigwin, L.D.; Southon, J.; Fernandez, D.P.; Wang, S.-L.; Scheirer, D.S.

2005-01-01

We present a detailed history of glacial to Holocene radiocarbon in the deep western North Atlantic from deep-sea corals and paired benthic-planktonic foraminifera. The deglaciation is marked by switches between radiocarbon-enriched and -depleted waters, leading to large radiocarbon gradients in the water column. These changes played an important role in modulating atmospheric radiocarbon. The deep-ocean record supports the notion of a bipolar seesaw with increased Northern-source deep-water formation linked to Northern Hemisphere warming and the reverse. In contrast, the more frequent radiocarbon variations in the intermediate/deep ocean are associated with roughly synchronous changes at the poles.

Southern ocean winds during past (and future) warm periods and their affect on Agulhas Leakage and the Atlantic Merdional Overturning Circulation

NASA Astrophysics Data System (ADS)

Patel, N. P.; Deconto, R. M.; Condron, A.

2013-12-01

The leakage of Agulhas Current water into the South Atlantic is now thought to be a major player in global climate change. The volume of Agulhas Leakage is linked to the strength and position of southern westerlies. Past changes in the westerly winds over the southern ocean have been noted on glacial-interglacial timescales, in response to both Northern Hemispheric conditions and more proximal changes in Antarctic ice volume. Over recent decades, a southward shift in the southern ocean westerlies has been observed and is expected to continue with projected climate warming. The resulting increase in Agulhas Leakage is thought to allow more warm, salty water from the Indian Ocean into the Atlantic, with the potential to impact the Atlantic Meridional Overturning circulation (AMOC). Some climate models have predicted global warming will result in a slowdown and weakening of the AMOC. A strengthening of the Agulhas Leakage therefore has the potential to counteract that slowdown. Much of the Agulhas leakage is carried in small eddies rotating off the main flow south of Cape Horn. High ocean model resolution (< 1/2°) is therefore required to simulate their response to the overlying wind field. However the majority of previous model studies have been too coarse in resolution to quantify the link between the Agulhas Leakage the AMOC. Here we run a series of global high-resolution ocean model (1/6°) experiments using the MITgcm to test the effect of a shift in the southern hemisphere westerlies on the Agulhas Leakage. A prescribed perturbation of the winds near South Africa shows a significant increase in Agulhas eddies into the Atlantic. Following this, we have conducted longer simulations with the winds over the Southern Ocean perturbed to reflect both past and possible future shifts in the wind field to quantify changes in North Atlantic Deep Water formation and the overall response of the AMOC to this perturbation.

Reconstructing Deep Ocean Circulation in the North Atlantic from Bermuda Rise, and Beyond

NASA Astrophysics Data System (ADS)

McManus, J. F.

2016-12-01

The large-scale subsurface circulation of the ocean is an important component of the Earth's climate system, and contributes to the global and regional transport of heat and mass. Assessing how this system has changed in the past is thus a priority for understanding natural climate variability. A long-coring campaign on Bermuda Rise has provided additional abundant high-quality sediments from this site of rapid accumulation in the deep western basin, situated beneath the subtropical gyre of the North Atlantic Ocean. These sediments allow the high-resolution reconstruction of deepwater chemistry and export from this key location throughout the last 150,000 years, covering the entire last glacial cycle in a continuous section of 35 meters in core KNR191-CDH19. The suite of proxy indicators analyzed includes uranium-series disequilibria, neodymium isotopes, and benthic stable isotopes. Combined with multiple previous studies of nearby cores on Bermuda Rise, the published and new proxy data from CDH19 confirm the variability of the deep circulation in the Atlantic Ocean in association with past climate changes. The multiple indicators, along with complementary data from other locations, display coherent evidence for contrasts between deep circulation during glacial and interglacial intervals, with persistent strong, deep ventilation only within the peak interglacial of marine isotope stage 5e (MIS 5e) and the Holocene. In contrast, repeated, dramatic variability in deep ocean circulation accompanied the millennial climate changes of the last glaciation and deglaciation. The largest magnitude circulation shifts occurred at the transitions into stadials associated with the Hudson strait iceberg discharges and between them and the ensuing northern interstadial warmings, significantly exceeding that of the overall glacial-interglacial difference, highlighting the potential oceanographic and climatic importance of short-term perturbations to the deep ocean circulation.

North Atlantic climate variability: The role of the North Atlantic Oscillation

NASA Astrophysics Data System (ADS)

Hurrell, James W.; Deser, Clara

2009-08-01

Marine ecosystems are undergoing rapid change at local and global scales. To understand these changes, including the relative roles of natural variability and anthropogenic effects, and to predict the future state of marine ecosystems requires quantitative understanding of the physics, biogeochemistry and ecology of oceanic systems at mechanistic levels. Central to this understanding is the role played by dominant patterns or "modes" of atmospheric and oceanic variability, which orchestrate coherent variations in climate over large regions with profound impacts on ecosystems. We review the spatial structure of extratropical climate variability over the Northern Hemisphere and, specifically, focus on modes of climate variability over the extratropical North Atlantic. A leading pattern of weather and climate variability over the Northern Hemisphere is the North Atlantic Oscillation (NAO). The NAO refers to a redistribution of atmospheric mass between the Arctic and the subtropical Atlantic, and swings from one phase to another producing large changes in surface air temperature, winds, storminess and precipitation over the Atlantic as well as the adjacent continents. The NAO also affects the ocean through changes in heat content, gyre circulations, mixed layer depth, salinity, high latitude deep water formation and sea ice cover. Thus, indices of the NAO have become widely used to document and understand how this mode of variability alters the structure and functioning of marine ecosystems. There is no unique way, however, to define the NAO. Several approaches are discussed including both linear (e.g., principal component analysis) and nonlinear (e.g., cluster analysis) techniques. The former, which have been most widely used, assume preferred atmospheric circulation states come in pairs, in which anomalies of opposite polarity have the same spatial structure. In contrast, nonlinear techniques search for recurrent patterns of a specific amplitude and sign. They reveal

North Atlantic climate variability: The role of the North Atlantic Oscillation

NASA Astrophysics Data System (ADS)

Hurrell, James W.; Deser, Clara

2010-02-01

Marine ecosystems are undergoing rapid change at local and global scales. To understand these changes, including the relative roles of natural variability and anthropogenic effects, and to predict the future state of marine ecosystems requires quantitative understanding of the physics, biogeochemistry and ecology of oceanic systems at mechanistic levels. Central to this understanding is the role played by dominant patterns or "modes" of atmospheric and oceanic variability, which orchestrate coherent variations in climate over large regions with profound impacts on ecosystems. We review the spatial structure of extratropical climate variability over the Northern Hemisphere and, specifically, focus on modes of climate variability over the extratropical North Atlantic. A leading pattern of weather and climate variability over the Northern Hemisphere is the North Atlantic Oscillation (NAO). The NAO refers to a redistribution of atmospheric mass between the Arctic and the subtropical Atlantic, and swings from one phase to another producing large changes in surface air temperature, winds, storminess and precipitation over the Atlantic as well as the adjacent continents. The NAO also affects the ocean through changes in heat content, gyre circulations, mixed layer depth, salinity, high latitude deep water formation and sea ice cover. Thus, indices of the NAO have become widely used to document and understand how this mode of variability alters the structure and functioning of marine ecosystems. There is no unique way, however, to define the NAO. Several approaches are discussed including both linear (e.g., principal component analysis) and nonlinear (e.g., cluster analysis) techniques. The former, which have been most widely used, assume preferred atmospheric circulation states come in pairs, in which anomalies of opposite polarity have the same spatial structure. In contrast, nonlinear techniques search for recurrent patterns of a specific amplitude and sign. They reveal

Characterization and impact of "dead-zone" eddies in the tropical Northeast Atlantic Ocean

NASA Astrophysics Data System (ADS)

Schuette, Florian; Karstensen, Johannes; Krahmann, Gerd; Hauss, Helena; Fiedler, Björn; Brandt, Peter; Visbeck, Martin; Körtzinger, Arne

2016-04-01

Localized open-ocean low-oxygen dead-zones in the tropical Northeast Atlantic are recently discovered ocean features that can develop in dynamically isolated water masses within cyclonic eddies (CE) and anticyclonic modewater eddies (ACME). Analysis of a comprehensive oxygen dataset obtained from gliders, moorings, research vessels and Argo floats shows that eddies with low oxygen concentrations at 50-150 m depths can be found in surprisingly high numbers and in a large area (from about 5°N to 20°N, from the shelf at the eastern boundary to 30°W). Minimum oxygen concentrations of about 9 μmol/kg in CEs and close to anoxic concentrations (< 1 μmol/kg) in ACMEs were observed. In total, 495 profiles with oxygen concentrations below the minimum background concentration of 40 μmol/kg could be associated with 27 independent "dead-zone" eddies (10 CEs; 17 ACMEs). The low oxygen concentration right beneath the mixed layer has been attributed to the combination of high productivity in the surface waters of the eddies and the isolation of the eddies' cores. Indeed eddies of both types feature a cold sea surface temperature anomaly and enhanced chlorophyll concentrations in their center. The oxygen minimum is located in the eddy core beneath the mixed layer at around 80 m depth. The mean oxygen anomaly between 50 to 150 m depth for CEs (ACMEs) is -49 (-81) μmol/kg. Eddies south of 12°N carry weak hydrographic anomalies in their cores and seem to be generated in the open ocean away from the boundary. North of 12°N, eddies of both types carry anomalously low salinity water of South Atlantic Central Water origin from the eastern boundary upwelling region into the open ocean. This points to an eddy generation near the eastern boundary. A conservative estimate yields that around 5 dead-zone eddies (4 CEs; 1 ACME) per year entering the area north of 12°N between the Cap Verde Islands and 19°W. The associated contribution to the oxygen budget of the shallow oxygen minimum

Transport and deposition of the fire biomarker levoglucosan across the tropical North Atlantic Ocean

NASA Astrophysics Data System (ADS)

Schreuder, Laura T.; Hopmans, Ellen C.; Stuut, Jan-Berend W.; Sinninghe Damsté, Jaap S.; Schouten, Stefan

2018-04-01

Biomass burning impacts biogeochemical cycling, vegetation dynamics and climate. However, interactions between fire, climate and vegetation are not well understood and therefore studies have attempted to reconstruct fire and vegetation history under different climatic conditions using sedimentary archives. Here we focus on levoglucosan, a thermal by-product of cellulose generated during biomass burning, and, therefore, a potential fire biomarker in the marine sedimentary archive. However, before levoglucosan can be applied as a biomass burning proxy in marine sediments, there is a need for studies on how levoglucosan is transported to the marine environment, how it is reflecting biomass burning on continents, as well as the fate of levoglucosan in the marine water column and during deposition in marine sediments. Here we present analyses of levoglucosan, using an improved Ultra High Pressure Liquid Chromatography-Electro Spray Ionization/High Resolution Mass Spectrometry (UHPLC-ESI/HRMS) method, in atmospheric particles, in particulate matter settling through the water column and in marine surface sediments on a longitudinal transect crossing the tropical North Atlantic Ocean at 12°N. Levoglucosan was detected in the atmosphere, although in low concentration, possibly due to the sampled particle size, the source area of the aerosols, or the short time interval of sampling by which large burning events may have been missed. In sinking particles in the tropical North Atlantic Ocean we find that levoglucosan deposition is influenced by a mineral ballast effect associated with marine biogenic particles, and that levoglucosan is not transported in association with mineral dust particles. Highest levoglucosan concentrations and seasonal differences in sinking particles were found close to continents and low concentrations and seasonal differences were found in the open ocean. Close to Africa, levoglucosan concentration is higher during winter, reflecting seasonal

Iron Biogeochemistry in the High Latitude North Atlantic Ocean.

PubMed

Achterberg, Eric P; Steigenberger, Sebastian; Marsay, Chris M; LeMoigne, Frédéric A C; Painter, Stuart C; Baker, Alex R; Connelly, Douglas P; Moore, C Mark; Tagliabue, Alessandro; Tanhua, Toste

2018-01-19

Iron (Fe) is an essential micronutrient for marine microbial organisms, and low supply controls productivity in large parts of the world's ocean. The high latitude North Atlantic is seasonally Fe limited, but Fe distributions and source strengths are poorly constrained. Surface ocean dissolved Fe (DFe) concentrations were low in the study region (<0.1 nM) in summer 2010, with significant perturbations during spring 2010 in the Iceland Basin as a result of an eruption of the Eyjafjallajökull volcano (up to 2.5 nM DFe near Iceland) with biogeochemical consequences. Deep water concentrations in the vicinity of the Reykjanes Ridge system were influenced by pronounced sediment resuspension, with indications for additional inputs by hydrothermal vents, with subsequent lateral transport of Fe and manganese plumes of up to 250-300 km. Particulate Fe formed the dominant pool, as evidenced by 4-17 fold higher total dissolvable Fe compared with DFe concentrations, and a dynamic exchange between the fractions appeared to buffer deep water DFe. Here we show that Fe supply associated with deep winter mixing (up to 103 nmol m -2 d -1 ) was at least ca. 4-10 times higher than atmospheric deposition, diffusive fluxes at the base of the summer mixed layer, and horizontal surface ocean fluxes.

Deep-sea whale fall fauna from the Atlantic resembles that of the Pacific Ocean.

PubMed

Sumida, Paulo Y G; Alfaro-Lucas, Joan M; Shimabukuro, Mauricio; Kitazato, Hiroshi; Perez, Jose A A; Soares-Gomes, Abilio; Toyofuku, Takashi; Lima, Andre O S; Ara, Koichi; Fujiwara, Yoshihiro

2016-02-24

Whale carcasses create remarkable habitats in the deep-sea by producing concentrated sources of organic matter for a food-deprived biota as well as places of evolutionary novelty and biodiversity. Although many of the faunal patterns on whale falls have already been described, the biogeography of these communities is still poorly known especially from basins other than the NE Pacific Ocean. The present work describes the community composition of the deepest natural whale carcass described to date found at 4204 m depth on Southwest Atlantic Ocean with manned submersible Shinkai 6500. This is the first record of a natural whale fall in the deep Atlantic Ocean. The skeleton belonged to an Antarctic Minke whale composed of only nine caudal vertebrae, whose degradation state suggests it was on the bottom for 5-10 years. The fauna consisted mainly of galatheid crabs, a new species of the snail Rubyspira and polychaete worms, including a new Osedax species. Most of the 41 species found in the carcass are new to science, with several genera shared with NE Pacific whale falls and vent and seep ecosystems. This similarity suggests the whale-fall fauna is widespread and has dispersed in a stepping stone fashion, deeply influencing its evolutionary history.

Deep-sea whale fall fauna from the Atlantic resembles that of the Pacific Ocean

NASA Astrophysics Data System (ADS)

Sumida, Paulo Y. G.; Alfaro-Lucas, Joan M.; Shimabukuro, Mauricio; Kitazato, Hiroshi; Perez, Jose A. A.; Soares-Gomes, Abilio; Toyofuku, Takashi; Lima, Andre O. S.; Ara, Koichi; Fujiwara, Yoshihiro

2016-02-01

Whale carcasses create remarkable habitats in the deep-sea by producing concentrated sources of organic matter for a food-deprived biota as well as places of evolutionary novelty and biodiversity. Although many of the faunal patterns on whale falls have already been described, the biogeography of these communities is still poorly known especially from basins other than the NE Pacific Ocean. The present work describes the community composition of the deepest natural whale carcass described to date found at 4204 m depth on Southwest Atlantic Ocean with manned submersible Shinkai 6500. This is the first record of a natural whale fall in the deep Atlantic Ocean. The skeleton belonged to an Antarctic Minke whale composed of only nine caudal vertebrae, whose degradation state suggests it was on the bottom for 5-10 years. The fauna consisted mainly of galatheid crabs, a new species of the snail Rubyspira and polychaete worms, including a new Osedax species. Most of the 41 species found in the carcass are new to science, with several genera shared with NE Pacific whale falls and vent and seep ecosystems. This similarity suggests the whale-fall fauna is widespread and has dispersed in a stepping stone fashion, deeply influencing its evolutionary history.

75 FR 8570 - Atlantic Ocean off John F. Kennedy Space Center, FL; Restricted Area

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-25

... off John F. Kennedy Space Center, FL; Restricted Area AGENCY: United States Army Corps of Engineers... the Atlantic Ocean off the coast of the John F. Kennedy Space Center (KSC), Florida. The KSC is the main launch facility for the National Aeronautics and Space Administration (NASA) and they need to have...

33 CFR 334.1050 - Oakland Outer Harbor adjacent to the Military Ocean Terminal, Bay Area, Pier No. 8 (Port of...

Code of Federal Regulations, 2011 CFR

2011-07-01

... the Military Ocean Terminal, Bay Area, Pier No. 8 (Port of Oakland Berth No. 10); restricted area. 334..., DEPARTMENT OF DEFENSE DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.1050 Oakland Outer Harbor adjacent to the Military Ocean Terminal, Bay Area, Pier No. 8 (Port of Oakland Berth No. 10); restricted area. (a...

33 CFR 334.1050 - Oakland Outer Harbor adjacent to the Military Ocean Terminal, Bay Area, Pier No. 8 (Port of...

Code of Federal Regulations, 2014 CFR

2014-07-01

... the Military Ocean Terminal, Bay Area, Pier No. 8 (Port of Oakland Berth No. 10); restricted area. 334..., DEPARTMENT OF DEFENSE DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.1050 Oakland Outer Harbor adjacent to the Military Ocean Terminal, Bay Area, Pier No. 8 (Port of Oakland Berth No. 10); restricted area. (a...

33 CFR 334.1050 - Oakland Outer Harbor adjacent to the Military Ocean Terminal, Bay Area, Pier No. 8 (Port of...

Code of Federal Regulations, 2010 CFR

2010-07-01

... the Military Ocean Terminal, Bay Area, Pier No. 8 (Port of Oakland Berth No. 10); restricted area. 334..., DEPARTMENT OF DEFENSE DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.1050 Oakland Outer Harbor adjacent to the Military Ocean Terminal, Bay Area, Pier No. 8 (Port of Oakland Berth No. 10); restricted area. (a...

33 CFR 334.1050 - Oakland Outer Harbor adjacent to the Military Ocean Terminal, Bay Area, Pier No. 8 (Port of...

Code of Federal Regulations, 2012 CFR

2012-07-01

... the Military Ocean Terminal, Bay Area, Pier No. 8 (Port of Oakland Berth No. 10); restricted area. 334..., DEPARTMENT OF DEFENSE DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.1050 Oakland Outer Harbor adjacent to the Military Ocean Terminal, Bay Area, Pier No. 8 (Port of Oakland Berth No. 10); restricted area. (a...

33 CFR 334.1050 - Oakland Outer Harbor adjacent to the Military Ocean Terminal, Bay Area, Pier No. 8 (Port of...

Code of Federal Regulations, 2013 CFR

2013-07-01

... the Military Ocean Terminal, Bay Area, Pier No. 8 (Port of Oakland Berth No. 10); restricted area. 334..., DEPARTMENT OF DEFENSE DANGER ZONE AND RESTRICTED AREA REGULATIONS § 334.1050 Oakland Outer Harbor adjacent to the Military Ocean Terminal, Bay Area, Pier No. 8 (Port of Oakland Berth No. 10); restricted area. (a...

The air-sea exchange of mercury in the low latitude Pacific and Atlantic Oceans

NASA Astrophysics Data System (ADS)

Mason, Robert P.; Hammerschmidt, Chad R.; Lamborg, Carl H.; Bowman, Katlin L.; Swarr, Gretchen J.; Shelley, Rachel U.

2017-04-01

Air-sea exchange is an important component of the global mercury (Hg) cycle as it mediates the rate of increase in ocean Hg, and therefore the rate of change in levels of methylmercury (MeHg), the most toxic and bioaccumulative form of Hg in seafood and the driver of human health concerns. Gas evasion of elemental Hg (Hg0) from the ocean is an important sink for ocean Hg with previous studies suggesting that evasion is not uniform across ocean basins. To understand further the factors controlling Hg0 evasion, and its relationship to atmospheric Hg deposition, we made measurements of dissolved Hg0 (DHg0) in surface waters, along with measurements of Hg in precipitation and on aerosols, and Hg0 in marine air, during two GEOTRACES cruises; GP16 in the equatorial South Pacific and GA03 in the North Atlantic. We contrast the concentrations and estimated evasion fluxes of Hg0 during these cruises, and the factors influencing this exchange. Concentrations of DHg0 and fluxes were lower during the GP16 cruise than during the GA03 cruise, and likely reflect the lower atmospheric deposition in the South Pacific. An examination of Hg/Al ratios for aerosols from the cruises suggests that they were anthropogenically-enriched relative to crustal material, although to a lesser degree for the South Pacific than the aerosols over the North Atlantic. Both regions appear to be net sources of Hg0 to the atmosphere (evasion>deposition) and the reasons for this are discussed. Overall, the studies reported here provide further clarification on the factors controlling evasion of Hg0 from the ocean surface, and the role of anthropogenic inputs in influencing ocean Hg concentrations.

Microbial community diversity of the eastern Atlantic Ocean reveals geographic differences

NASA Astrophysics Data System (ADS)

Friedline, C. J.; Franklin, R. B.; McCallister, S. L.; Rivera, M. C.

2012-01-01

Prokaryotic communities are recognized as major drivers of the biogeochemical processes in the oceans. However, the genetic diversity and composition of those communities is poorly understood. The aim of this study was to investigate the eubacterial communities in three different water layers: surface (2-20 m), deep chlorophyll maximum (DCM; 28-90 m), and deep (100-4600 m) at nine stations along the eastern Atlantic Ocean from 42.8° N to 23.7° S. In order to describe the dynamics of the eubacterial assemblages in relation to depth, associated environmental properties, and Longhurstian ecological provinces community DNA was extracted from 16 samples, from which the V6 region of 16s rDNA was PCR-amplified with eubacteria-specific primers, and the PCR amplicons were pyrosequenced. A total of 352 029 sequences were generated; after quality filtering and processing, 257 260 sequences were clustered into 2871 normalized Operational Taxonomic Units (OTU) using a definition of 97% sequence identity. Comparisons of the phylogenetic affiliation of those 2871 OTUs show more than 54% of them were assigned to the Proteobacteria, with the Alphaproteobacteria representing 4% of the total Proteobacteria OTUs, and the Gammaproteobacteria representing 22%. Within the Alphaproteobacteria-affiliated OTUs, 44% of the OTUs were associated with the ubiquitous SAR11 clade. The phylum Cyanobacteria represent 10% of the reads, with the majority of those reads among the GpIIa family including Prochlorococcus and Synechococcus. Among the Gammaproteobacteria, a single OTU affiliated to Alteromonas comprises ~3% of the abundance. The phyla Bacteroidetes, Verrucomicrobia, Actinobacteria, and Firmicutes represent approximately 7%, 0.8%, 2%, and 0.05% of the read abundance, respectively. Community ecology statistical analyses and a novel implementation of Bayesian inference suggests that eastern Atlantic Ocean eubacterial assemblages are vertically stratified and associated with water layers

The not-so-silent world: Measuring Arctic, Equatorial, and Antarctic soundscapes in the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Haver, Samara M.; Klinck, Holger; Nieukirk, Sharon L.; Matsumoto, Haru; Dziak, Robert P.; Miksis-Olds, Jennifer L.

2017-04-01

Anthropogenic noise in the ocean has been shown, under certain conditions, to influence the behavior and health of marine mammals. Noise from human activities may interfere with the low-frequency acoustic communication of many Mysticete species, including blue (Balaenoptera musculus) and fin whales (B. physalus). This study analyzed three soundscapes in the Atlantic Ocean, from the Arctic to the Antarctic, to document ambient sound. For 16 months beginning in August 2009, acoustic data (15-100 Hz) were collected in the Fram Strait (79°N, 5.5°E), near Ascension Island (8°S, 14.4°W) and in the Bransfield Strait (62°S, 55.5°W). Results indicate (1) the highest overall sound levels were measured in the equatorial Atlantic, in association with high levels of seismic oil and gas exploration, (2) compared to the tropics, ambient sound levels in polar regions are more seasonally variable, and (3) individual elements beget the seasonal and annual variability of ambient sound levels in high latitudes. Understanding how the variability of natural and man-made contributors to sound may elicit differences in ocean soundscapes is essential to developing strategies to manage and conserve marine ecosystems and animals.

Nitrous oxide and methane in the Atlantic Ocean between 50°N and 52°S: Latitudinal distribution and sea-to-air flux

NASA Astrophysics Data System (ADS)

Forster, Grant; Upstill-Goddard, Rob C.; Gist, Niki; Robinson, Carol; Uher, Gunther; Woodward, E. Malcolm S.

2009-07-01

We discuss nitrous oxide (N 2O) and methane (CH 4) distributions in 49 vertical profiles covering the upper ˜300 m of the water column along two ˜13,500 km transects between ˜50°N and ˜52°S during the Atlantic Meridional Transect (AMT) programme (AMT cruises 12 and 13). Vertical N 2O profiles were amenable to analysis on the basis of common features coincident with Longhurst provinces. In contrast, CH 4 showed no such pattern. The most striking feature of the latitudinal depth distributions was a well-defined "plume" of exceptionally high N 2O concentrations coincident with very low levels of CH 4, located between ˜23.5°N and ˜23.5°S; this feature reflects the upwelling of deep waters containing N 2O derived from nitrification, as identified by an analysis of N 2O, apparent oxygen utilization (AOU) and NO 3-, and presumably depleted in CH 4 by bacterial oxidation. Sea-to-air emissions fluxes for a region equivalent to ˜42% of the Atlantic Ocean surface area were in the range 0.40-0.68 Tg N 2O yr -1 and 0.81-1.43 Tg CH 4 yr -1. Based on contemporary estimates of the global ocean source strengths of atmospheric N 2O and CH 4, the Atlantic Ocean could account for ˜6-15% and 4-13%, respectively, of these source totals. Given that the Atlantic Ocean accounts for around 20% of the global ocean surface, on unit area basis it appears that the Atlantic may be a slightly weaker source of atmospheric N 2O than other ocean regions but it could make a somewhat larger contribution to marine-derived atmospheric CH 4 than previously thought.

Surface temperatures of the Mid-Pliocene North Atlantic Ocean: Implications for future climate

USGS Publications Warehouse

Dowsett, Harry J.; Chandler, Mark A.; Robinson, Marci M.

2009-01-01

The Mid-Pliocene is the most recent interval in the Earth's history to have experienced warming of the magnitude predicted for the second half of the twenty-first century and is, therefore, a possible analogue for future climate conditions. With continents basically in their current positions and atmospheric CO2 similar to early twenty-first century values, the cause of Mid-Pliocene warmth remains elusive. Understanding the behaviour of the North Atlantic Ocean during the Mid-Pliocene is integral to evaluating future climate scenarios owing to its role in deep water formation and its sensitivity to climate change. Under the framework of the Pliocene Research, Interpretation and Synoptic Mapping (PRISM) sea surface reconstruction, we synthesize Mid-Pliocene North Atlantic studies by PRISM members and others, describing each region of the North Atlantic in terms of palaeoceanography. We then relate Mid-Pliocene sea surface conditions to expectations of future warming. The results of the data and climate model comparisons suggest that the North Atlantic is more sensitive to climate change than is suggested by climate model simulations, raising the concern that estimates of future climate change are conservative.

Enhancement of the southward return flow of the Atlantic Meridional Overturning Circulation by data assimilation and its influence in an assimilative ocean simulation forced by CORE-II atmospheric forcing

NASA Astrophysics Data System (ADS)

Fujii, Yosuke; Tsujino, Hiroyuki; Toyoda, Takahiro; Nakano, Hideyuki

2017-08-01

This paper examines the difference in the Atlantic Meridional Overturning Circulation (AMOC) mean state between free and assimilative simulations of a common ocean model using a common interannual atmospheric forcing. In the assimilative simulation, the reproduction of cold cores in the Nordic Seas, which is absent in the free simulation, enhances the overflow to the North Atlantic and improves AMOC with enhanced transport of the deeper part of the southward return flow. This improvement also induces an enhanced supply of North Atlantic Deep Water (NADW) and causes better representation of the Atlantic deep layer despite the fact that correction by the data assimilation is applied only to temperature and salinity above a depth of 1750 m. It also affects Circumpolar Deep Water in the Southern Ocean. Although the earliest influence of the improvement propagated by coastal waves reaches the Southern Ocean in 10-15 years, substantial influence associated with the arrival of the renewed NADW propagates across the Atlantic Basin in several decades. Although the result demonstrates that data assimilation is able to improve the deep ocean state even if there is no data there, it also indicates that long-term integration is required to reproduce variability in the deep ocean originating from variations in the upper ocean. This study thus provides insights on the reliability of AMOC and the ocean state in the Atlantic deep layer reproduced by data assimilation systems.

1.5 My benthic foraminiferal B/Ca record of carbonate chemistry in the deep Atlantic: Implications for ocean alkalinity and atmospheric CO2

NASA Astrophysics Data System (ADS)

Rosenthal, Y.; Sosdian, S. M.; Toggweiler, J. R.

2017-12-01

Most hypotheses to explain glacial-interglacial changes in atmospheric CO2 invoke shifts in ocean alkalinity explain roughly half the reduction in glacial CO2 via CaCO3 compensatory mechanism. It follows that changes in CaCO3 burial occur in response to an increase in deep ocean respired carbon content. To date our understanding of this process comes from benthic carbon isotope and %CaCO3 records. However, to understand the nature of the ocean's buffering capacity and its role in modulating pCO2, orbitally resolved reconstructions of the deep ocean carbonate system parameters are necessary. Here we present a 1.5 Myr orbitally resolved deep ocean calcite saturation record (ΔCO32-) derived from benthic foraminiferal B/Ca ratios in the North Atlantic. Glacial B/Ca values decline across the mid-Pleistocene transition (MPT) suggesting increased sequestration of carbon in the deep Atlantic. The magnitude, timing, and structure of deep Atlantic Ocean ΔCO32- and %CaCO3 cycles contrast with the small amplitude, anti-phased swings in IndoPacific ΔCO32- and %CaCO3 during the mid-to-late Pleistocene. Increasing corrosivity of the deep Atlantic causes the locus of CaCO3 burial to shift into the equatorial Pacific where the flux of CaCO3 to the seafloor is high enough to establish and maintain a new "hot spot". We propose that the CO32- in the deep IndoPacific rises in response to the same mechanism that keeps the CO32- in the deep Atlantic low and the atmospheric CO2 low. The increase in interglacial atmospheric pCO2 levels following the Mid-Brunhes event ( 400ka) are associated with increased G/IG ΔCO3 amplitude, expressed by a decrease in the glacial ΔCO32- values. We propose the low persistent ΔCO32- levels at Marine Isotope Stage (MIS) 12 set the stage for the high pCO2 levels at MIS 11 via an increase in whole ocean alkalinity followed by enhanced CaCO3 preservation. Based on this, we suggest that the development of classic (`anticorrelated') CaCO3 patterns was

Changes in Equatorial Atlantic Ocean Thermohaline Circulation Across the Mid-Pleistocene Transition

NASA Astrophysics Data System (ADS)

Yehudai, M.; Kim, J.; Seguí, M. J.; Goldstein, S. L.; Pena, L. D.; Haynes, L.; Hoenisch, B.; Farmer, J. R.; Ford, H. L.; Raymo, M. E.; Bickert, T.

2016-12-01

The Mid-Pleistocene Transition (MPT) marked a change in the duration of glacial-interglacial cycles from 41 to 100kyr between 1.3-0.7 Ma. A recent study (Pena and Goldstein, Science, 2014) from the Southern Atlantic Ocean found evidence for major disruptions in the global thermohaline circulation (THC) between MIS 25-21 ( 950-850ka), which may have triggered intensified glacial periods and the onset of the 100 kyr cycles. We report new Nd isotope data on Fe-Mn oxide encrusted foraminifera and fish debris from ODP Site 926 (3.719N, 42.908W, 3598m) between 1.2-0.4 Ma, in order to evaluate changes in the THC in the equatorial Atlantic, through comparison with North and South Atlantic sites. The ODP 926 ɛNd values fall in-between those in the North Atlantic (DSDP 607) and South Atlantic (ODP 1088 and 1090) throughout the studied interval, consistent with mixing between northern and southern end-members, and supporting the interpretation that the data represent the THC signal at this site. Pre-MPT data show smaller glacial-interglacial differences compared to the greater post-MPT glacial-interglacial variability. As Pena and Goldstein (2014) observed in the South Atlantic, during MIS 23 at 900 ka, ɛNd values do not shift significantly toward North Atlantic more negative values, consistent with a weak THC through this critical weak interglacial. Comparing ODP 926 and DSDP 607 data, ɛNd values converge during most interglacial peaks (excepting MIS 23) and diverge otherwise. This observation indicates that northern-sourced water masses dominate the site during peak interglacials, and confirms that the THC has been strongest during peak interglacials throughout the studied interval. Otherwise, diverging ɛNd values indicate a stronger southern-source signal and weaker northern-source signal at the ODP 926 site. This confirms that there was an active but variable THC system before, during, and after the MPT, with stronger deep water export from the North Atlantic during

Carbon 14 measurements in surface water CO{sub 2} from the Atlantic, India, and Pacific Oceans, 1965--1994

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nydal, R.; Brenkert, A.L.; Boden, T.A.

1998-03-01

In the 1960s, thermonuclear bomb tests released significant pulses of radioactive carbon-14 ({sup 14}C) into the atmosphere. These major perturbations allowed scientists to study the dynamics of the global carbon cycle by calculating rates of isotope exchange between the atmosphere and ocean waters. A total of 950 ocean surface water observations were made from 1965 through 1994. The measurements were taken at 30 stations in the Atlantic Ocean, 14 stations in the Indian Ocean, and 38 stations in the Pacific Ocean. Thirty-two of the 950 samples were taken in the Atlantic Ocean during the R/V Andenes research cruise. {sup 14}Cmore » was measured in 871 of the 950 samples, and those measurements have been corrected ({Delta}{sup 14}C) for isotopic fractionation and radioactive decay. The {Delta}{sup 14}C values range between {minus}113.3 and 280.9 per mille and have a mean value of 101.3 per mille. The highest yearly mean (146.5 per mille) was calculated for 1969, the lowest yearly mean value was calculated for 1990 (67.9 per mille) illustrating a decrease over time. This decrease was to be expected as a result of the ban on atmospheric thermonuclear tests and the slow mixing of the ocean surface waters with the deeper layers.« less

MAX-DOAS measurements of African continental pollution outflow over the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Behrens, Lisa K.; Hilboll, Andreas; Peters, Enno; Richter, Andreas; Alvarado, Leonardo; Wittrock, Folkard; Burrows, John P.; Vrekoussis, Mihalis

2017-04-01

Enhanced levels of atmospheric key pollutants can regularly be identified over the Atlantic Ocean in global trace gas maps retrieved from satellite measurements. The aim of the DFG project COPMAR (Continental outflow of pollutants towards the marine troposphere) was to validate these enhanced values using ship-based measurements and to identify the spatial gradients of the pollutants NO2, CHOCHO, and HCHO over the Atlantic Ocean. Therefore, a multi-axis differential optical absorption spectrometer (MAX-DOAS) was installed on board the research vessel Maria S. Merian for the cruise MSM58/2. This cruise was conducted in October 2016 and went from Ponta Delgada (Azores) to Cape Town (South Africa), crossing between Cape Verde and the African continent. The instrument was continuously scanning the horizon looking towards the African continent, and the ship sailed at nearly constant speed during the whole cruise. In this study, we present the results from the MAX-DOAS measurements for the three species. We discuss the influence of different fit settings and a-priori assumptions on the results and present the observed spatial gradients along the cruise track. Finally, we compare our results with satellite measurements by the GOME-2 and OMI instruments and discuss possible sources of the discrepancies.

Mitochondrial acclimation potential to ocean acidification and warming of Polar cod (Boreogadus saida) and Atlantic cod (Gadus morhua).

PubMed

Leo, Elettra; Kunz, Kristina L; Schmidt, Matthias; Storch, Daniela; Pörtner, Hans-O; Mark, Felix C

2017-01-01

Ocean acidification and warming are happening fast in the Arctic but little is known about the effects of ocean acidification and warming on the physiological performance and survival of Arctic fish. In this study we investigated the metabolic background of performance through analyses of cardiac mitochondrial function in response to control and elevated water temperatures and P CO 2 of two gadoid fish species, Polar cod ( Boreogadus saida ), an endemic Arctic species, and Atlantic cod ( Gadus morhua ), which is a temperate to cold eurytherm and currently expanding into Arctic waters in the wake of ocean warming. We studied their responses to the above-mentioned drivers and their acclimation potential through analysing the cardiac mitochondrial function in permeabilised cardiac muscle fibres after 4 months of incubation at different temperatures (Polar cod: 0, 3, 6, 8 °C and Atlantic cod: 3, 8, 12, 16 °C), combined with exposure to present (400μatm) and year 2100 (1170μatm) levels of CO 2 . OXPHOS, proton leak and ATP production efficiency in Polar cod were similar in the groups acclimated at 400μatm and 1170μatm of CO 2 , while incubation at 8 °C evoked increased proton leak resulting in decreased ATP production efficiency and decreased Complex IV capacity. In contrast, OXPHOS of Atlantic cod increased with temperature without compromising the ATP production efficiency, whereas the combination of high temperature and high P CO 2 depressed OXPHOS and ATP production efficiency. Polar cod mitochondrial efficiency decreased at 8 °C while Atlantic cod mitochondria were more resilient to elevated temperature; however, this resilience was constrained by high P CO 2 . In line with its lower habitat temperature and higher degree of stenothermy, Polar cod has a lower acclimation potential to warming than Atlantic cod.

Open ocean dead zones in the tropical North Atlantic Ocean

NASA Astrophysics Data System (ADS)

Karstensen, J.; Fiedler, B.; Schütte, F.; Brandt, P.; Körtzinger, A.; Fischer, G.; Zantopp, R.; Hahn, J.; Visbeck, M.; Wallace, D.

2015-04-01

Here we present first observations, from instrumentation installed on moorings and a float, of unexpectedly low (<2 μmol kg-1) oxygen environments in the open waters of the tropical North Atlantic, a region where oxygen concentration does normally not fall much below 40 μmol kg-1. The low-oxygen zones are created at shallow depth, just below the mixed layer, in the euphotic zone of cyclonic eddies and anticyclonic-modewater eddies. Both types of eddies are prone to high surface productivity. Net respiration rates for the eddies are found to be 3 to 5 times higher when compared with surrounding waters. Oxygen is lowest in the centre of the eddies, in a depth range where the swirl velocity, defining the transition between eddy and surroundings, has its maximum. It is assumed that the strong velocity at the outer rim of the eddies hampers the transport of properties across the eddies boundary and as such isolates their cores. This is supported by a remarkably stable hydrographic structure of the eddies core over periods of several months. The eddies propagate westward, at about 4 to 5 km day-1, from their generation region off the West African coast into the open ocean. High productivity and accompanying respiration, paired with sluggish exchange across the eddy boundary, create the "dead zone" inside the eddies, so far only reported for coastal areas or lakes. We observe a direct impact of the open ocean dead zones on the marine ecosystem as such that the diurnal vertical migration of zooplankton is suppressed inside the eddies.

75 FR 34643 - Atlantic Ocean Off John F. Kennedy Space Center, FL; Restricted Area

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-18

... Off John F. Kennedy Space Center, FL; Restricted Area AGENCY: U.S. Army Corps of Engineers, DoD... establishing a new restricted area in the Atlantic Ocean off the coast of the John F. Kennedy Space Center (KSC), Florida. The KSC is the main launch facility for the National Aeronautics and Space Administration (NASA...

C : N : P stoichiometry at the Bermuda Atlantic Time-series Study station in the North Atlantic Ocean

NASA Astrophysics Data System (ADS)

Singh, A.; Baer, S. E.; Riebesell, U.; Martiny, A. C.; Lomas, M. W.

2015-06-01

Nitrogen (N) and phosphorus (P) availability determine the strength of the ocean's carbon (C) uptake, and variation in the N : P ratio in inorganic nutrients is key to phytoplankton growth. A similarity between C : N : P ratios in the plankton biomass and deep-water nutrients was observed by Alfred C. Redfield around 80 years ago and suggested that biological processes in the surface ocean controlled deep ocean chemistry. Recent studies have emphasized the role of inorganic N : P ratios in governing biogeochemical processes, particularly the C : N : P ratio in suspended particulate organic matter (POM), with somewhat less attention given to exported POM and dissolved organic matter (DOM). Herein, we extend the discussion on ecosystem C : N : P stoichiometry but also examine temporal variation of stoichiometric relationships. We have analysed elemental stoichiometry in the suspended POM and total (POM + DOM) organic matter (TOM) pools in the upper 100 m, and in the exported POM and sub-euphotic zone (100-500 m) inorganic nutrient pools from the monthly data collected at the Bermuda Atlantic Time-series Study (BATS) site located in the western part of the North Atlantic Ocean. C : N : P ratios in the TOM pool were more than twice that in the POM pool. Observed C : N ratios in suspended POM were approximately equal to the canonical Redfield Ratio (C : N : P = 106 : 16 : 1), while N : P and C : P ratios in the same pool were more than twice the Redfield Ratio. Average N : P ratios in the subsurface inorganic nutrient pool were ~ 26 : 1, squarely between the suspended POM ratio and the Redfield ratio. We have further linked variation in elemental stoichiometry with that of phytoplankton cell abundance observed at the BATS site. Findings from this study suggest that the variation elemental ratios with depth in the euphotic zone was mainly due to different growth rates of cyanobacterial cells. These time-series data have also allowed us to examine the potential role of

Downscaling ocean conditions with application to the Gulf of Maine, Scotian Shelf and adjacent deep ocean

NASA Astrophysics Data System (ADS)

Katavouta, Anna; Thompson, Keith R.

2016-08-01

The overall goal is to downscale ocean conditions predicted by an existing global prediction system and evaluate the results using observations from the Gulf of Maine, Scotian Shelf and adjacent deep ocean. The first step is to develop a one-way nested regional model and evaluate its predictions using observations from multiple sources including satellite-borne sensors of surface temperature and sea level, CTDs, Argo floats and moored current meters. It is shown that the regional model predicts more realistic fields than the global system on the shelf because it has higher resolution and includes tides that are absent from the global system. However, in deep water the regional model misplaces deep ocean eddies and meanders associated with the Gulf Stream. This is not because the regional model's dynamics are flawed but rather is the result of internally generated variability in deep water that leads to decoupling of the regional model from the global system. To overcome this problem, the next step is to spectrally nudge the regional model to the large scales (length scales > 90 km) of the global system. It is shown this leads to more realistic predictions off the shelf. Wavenumber spectra show that even though spectral nudging constrains the large scales, it does not suppress the variability on small scales; on the contrary, it favours the formation of eddies with length scales below the cutoff wavelength of the spectral nudging.

Heterogeneity of the North Atlantic oceanic lithosphere based on integrated analysis of GOCE satellite gravity and geological data

NASA Astrophysics Data System (ADS)

Barantseva, Olga; Artemieva, Irina; Thybo, Hans; Herceg, Matija

2015-04-01

We present the results from modelling the gravity and density structure of the upper mantle for the off-shore area of the North Atlantic region. The crust and upper mantle of the region is expected to be anomalous: Part of the region affected by the Icelandic plume has an anomalously shallow bathymetry, whereas the northern part of the region is characterized by ultraslow spreading. In order to understand the links between deep geodynamical processes that control the spreading rate, on one hand, and their manifestations such as oceanic floor bathymetry and heat flow, on the other hand, we model the gravity and density structure of the upper mantle from satellite gravity data. The calculations are based on interpretation of GOCE gravity satellite data for the North Atlantics. To separate the gravity signal responsible for density anomalies within the crust and upper mantle, we subtract the lower harmonics caused by deep density structure of the Earth (the core and the lower mantle). The gravity effect of the upper mantle is calculated by subtracting the gravity effect of the crust for two crustal models. We use a recent regional seismic model for the crustal structure (Artemieva and Thybo, 2013) based om seismic data together with borehole data for sediments. For comparison, similar results are presented for the global CRUST 1.0 model as well (Laske, 2013). The conversion of seismic velocity data for the crustal structure to crustal density structure is crucial for the final results. We use a combination of Vp-to-density conversion based on published laboratory measurements for the crystalline basement (Ludwig, Nafe, Drake, 1970; Christensen and Mooney, 1995) and for oceanic sediments and oceanic crust based on laboratory measurements for serpentinites and gabbros from the Mid-Atlantic Ridge (Kelemen et al., 2004). Also, to overcome the high degree of uncertainty in Vp-to-density conversion, we account for regional tectonic variations in the Northern Atlantics as

Evolution of the Arctic-North Atlantic and the Western Tethys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ziegler, P.A.

1988-01-01

This volume provides an overview of the late Paleozoic to recent geological evolution of the continents and shelves bordering the North Atlantic Ocean, the Norwegian-Greenland Sea, the Arctic Ocean, and the Mediterranean Sea. The evolution of these seas has been the subject of many studies and compilations, which discuss the evolution of oceanic basins on the basis of their magnetic sea-floor anomalies. The volume presented combines this information with geological data from the adjacent shelf and onshore areas. It retraces the evolution of sedimentary basins developed during the rifting phases that preceded the opening of these oceans and highlights themore » scope of the associated intra-plate phenomena. The author presents a reconstruction of the late Paleozoic and early Mesozoic development of Europe, northernmost Africa and northeastern North America-Greenland and discusses the different orogenic cycles that accompanied the stepwise assembly of Pangea and the early rifting phases heralding its break-up.« less

Molecular biogeochemical provinces in the Atlantic Surface Ocean

NASA Astrophysics Data System (ADS)

Koch, B. P.; Flerus, R.; Schmitt-Kopplin, P.; Lechtenfeld, O. J.; Bracher, A.; Cooper, W.; Frka, S.; Gašparović, B.; Gonsior, M.; Hertkorn, N.; Jaffe, R.; Jenkins, A.; Kuss, J.; Lara, R. J.; Lucio, M.; McCallister, S. L.; Neogi, S. B.; Pohl, C.; Roettgers, R.; Rohardt, G.; Schmitt, B. B.; Stuart, A.; Theis, A.; Ying, W.; Witt, M.; Xie, Z.; Yamashita, Y.; Zhang, L.; Zhu, Z. Y.; Kattner, G.

2010-12-01

One of the most important aspects to understand marine organic carbon fluxes is to resolve the molecular mechanisms which convert fresh, labile biomolecules into semi-labile and refractory dissolved and particulate organic compounds in the ocean. In this interdisciplinary project, which was performed on a cruise with RV Polarstern, we carried out a detailed molecular characterisation of dissolved organic matter (DOM) on a North-South transect in the Atlantic surface ocean in order to relate the data to different biological, climatic, oceanographic, and meteorological regimes as well as to terrestrial input from riverine and atmospheric sources. Our goal was to achieve a high resolution data set for the biogeochemical characterisation of the sources and reactivity of DOM. We applied ultrahigh resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS), nutrient, trace element, amino acid, and lipid analyses and other biogeochemical measurements for 220 samples from the upper water column (0-200m) and eight deep profiles. Various spectroscopic techniques were applied continuously in a constant sample water flow supplied by a fish system and the moon pool. Radiocarbon dating enabled assessing DOC residence time. Bacterial abundance and production provided a metabolic context for the DOM characterization work and pCO2 concentrations. Combining molecular organic techniques and inductively coupled plasma mass spectrometry (ICP-MS) established an important link between organic and inorganic biogeochemical studies. Multivariate statistics, primarily based on FT-ICR-MS data for 220 samples, allowed identifying geographical clusters which matched ecological provinces proposed previously by Longhurst (2007). Our study demonstrated that marine DOM carries molecular information reflecting the “history” of ocean water masses. This information can be used to define molecular biogeochemical provinces and to improve our understanding of element fluxes in

Greater role for Atlantic inflows on sea-ice loss in the Eurasian Basin of the Arctic Ocean

NASA Astrophysics Data System (ADS)

Polyakov, Igor V.; Pnyushkov, Andrey V.; Alkire, Matthew B.; Ashik, Igor M.; Baumann, Till M.; Carmack, Eddy C.; Goszczko, Ilona; Guthrie, John; Ivanov, Vladimir V.; Kanzow, Torsten; Krishfield, Richard; Kwok, Ronald; Sundfjord, Arild; Morison, James; Rember, Robert; Yulin, Alexander

2017-04-01

Arctic sea-ice loss is a leading indicator of climate change and can be attributed, in large part, to atmospheric forcing. Here, we show that recent ice reductions, weakening of the halocline, and shoaling of the intermediate-depth Atlantic Water layer in the eastern Eurasian Basin have increased winter ventilation in the ocean interior, making this region structurally similar to that of the western Eurasian Basin. The associated enhanced release of oceanic heat has reduced winter sea-ice formation at a rate now comparable to losses from atmospheric thermodynamic forcing, thus explaining the recent reduction in sea-ice cover in the eastern Eurasian Basin. This encroaching “atlantification” of the Eurasian Basin represents an essential step toward a new Arctic climate state, with a substantially greater role for Atlantic inflows.

NASA CYGNSS Ocean Wind Observations in the 2017 Atlantic Hurricane Season

NASA Astrophysics Data System (ADS)

Ruf, C. S.; Balasubramaniam, R.; Mayers, D.; McKague, D. S.

2017-12-01

The CYGNSS constellation of eight satellites was successfully launched on 15 December 2016 into a low inclination (tropical) Earth orbit to measure ocean surface wind speed in the inner core of tropical cyclones with better than 12 hour refresh rates. Each satellite carries a four-channel bi-static radar receiver that measures GPS signals scattered by the ocean, from which ocean surface roughness, near surface wind speed, and air-sea latent heat flux are estimated. The measurements are unique in several respects, most notably in their ability to penetrate through all levels of precipitation, made possible by the low frequency at which GPS operates, and in the frequent sampling of tropical cyclone intensification, made possible by the large number of satellites. Level 2 science data products have been developed for near surface (10 m referenced) ocean wind speed, ocean surface roughness (mean square slope) and latent heat flux. Level 3 gridded versions of the L2 products have also been developed. A set of Level 4 products have also been developed specifically for direct tropical cyclone overpasses. These include the storm intensity (peak sustained winds) and size (radius of maximum winds), its extent (34, 50 and 64 knot wind radii), and its integrated kinetic energy. Results of measurements made during the 2017 Atlantic hurricane season, including frequent overpasses of Hurricanes Harvey, Irma and Maria, will be presented.

Contrasting effects of climate change in continental vs. oceanic environments on population persistence and microevolution of Atlantic salmon.

PubMed

Piou, Cyril; Prévost, Etienne

2013-03-01

Facing climate change (CC), species are prone to multiple modifications in their environment that can lead to extinction, migration or adaptation. Identifying the role and interplay of different potential stressors becomes a key question. Anadromous fishes will be exposed to both river and oceanic habitat changes. For Atlantic salmon, the river water temperature, river flow and oceanic growth conditions appear as three main stressing factors. They could act on population dynamics or as selective forces on life-history pathways. Using an individual-based demo-genetic model, we assessed the effects of these factors (1) to compare risks of extinction resulting from CC in river and ocean, and (2) to assess CC effects on life-history pathways including the evolution of underlying genetic control of phenotypic plasticity. We focused on Atlantic salmon populations from Southern Europe for a time horizon of three decades. We showed that CC in river alone should not lead to extinction of Southern European salmon populations. In contrast, the reduced oceanic growth appeared as a significant threat for population persistence. An increase in river flow amplitude increased the risk of local extinction in synergy with the oceanic effects, but river temperature rise reduced this risk. In terms of life-history modifications, the reduced oceanic growth increased the age of return of individuals through plastic and genetic responses. The river temperature rise increased the proportion of sexually mature parr, but the genetic evolution of the maturation threshold lowered the maturation rate of male parr. This was identified as a case of environmentally driven plastic response that masked an underlying evolutionary response of plasticity going in the opposite direction. We concluded that to counteract oceanic effects, river flow management represented the sole potential force to reduce the extinction probability of Atlantic salmon populations in Southern Europe, although this might

Brazil, Atlantic Ocean, Africa & Antarctica seen from Apollo 4

NASA Image and Video Library

1967-11-09

AS04-01-580 (9 Nov. 1967) --- Earth as viewed from 10,000 miles. In 1969, the Apollo 4 (Spacecraft 017/Saturn 501) unmanned test flight made a great ellipse around Earth as a test of the translunar motors and of the high speed entry required of a manned flight returning from the moon. A 70mm camera was programmed to look out a window toward Earth, and take a series of photographs from "high apogee". Coastal Brazil, Atlantic Ocean, West Africa, Antarctica, looking west. This photograph was made when the Apollo 4 spacecraft, still attached to the S-IVB (third) stage, was orbiting Earth at an altitude of 9,544 miles.

Changes in erosion and ocean circulation recorded in the Hf isotopic compositions of North Atlantic and Indian Ocean ferromanganese crusts

USGS Publications Warehouse

Piotrowski, Alexander M.; Lee, Der-Chuen; Christensen, John N.; Burton, Kevin W.; Halliday, Alex N.; Hein, James R.; Günther, Detlef

2000-01-01

High-resolution Hf isotopic records are presented for hydrogenetic Fe–Mn crusts from the North Atlantic and Indian Oceans. BM1969 from the western North Atlantic has previously been shown to record systematically decreasing Nd isotopic compositions from about 60 to ∼4 Ma, at which time both show a rapid decrease to unradiogenic Nd composition, thought to be related to the increasing influence of NADW or glaciation in the northern hemisphere. During the Oligocene, North Atlantic Hf became progressively less radiogenic until in the mid-Miocene (∼15 Ma) it reached +1. It then shifted gradually back to an ϵHf value of +3 at 4 Ma, since when it has decreased rapidly to about −1 at the present day. The observed shifts in the Hf isotopic composition were probably caused by variation in intensity of erosion as glaciation progressed in the northern hemisphere. Ferromanganese crusts SS663 and 109D are from about 5500 m depth in the Indian Ocean and are now separated by ∼2300 km across the Mid-Indian Ridge. They display similar trends in Hf isotopic composition from 20 to 5 Ma, with the more northern crust having a composition that is consistently more radiogenic (by ∼2 ϵHf units). Paradoxically, during the last 20 Ma the Hf isotopic compositions of the two crusts have converged despite increased separation and subsidence relative to the ridge. A correlatable negative excursion at ∼5 Ma in the two records may reflect a short-term increase in erosion caused by the activation of the Himalayan main central thrust. Changes to unradiogenic Hf in the central Indian Ocean after 5 Ma may alternatively have been caused by the expanding influence of NADW into the Mid-Indian Basin via circum-Antarctic deep water or a reduction of Pacific flow through the Indonesian gateway. In either case, these results illustrate the utility of the Hf isotope system as a tracer of paleoceanographic changes, capable of responding to subtle changes in erosional regime not readily resolved

STS-44 Earth observation shows purplish twilight over the Atlantic Ocean

NASA Technical Reports Server (NTRS)

1991-01-01

STS-44 Earth observation taken aboard Atlantis, Orbiter Vehicle (OV) 104, shows twilight over the Atlantic Ocean. OV-104 was at a point in the north Atlantic located at 28 degrees north latitude and 37 degrees west longitude. The spacecraft has just passed sundown on the Earth's surface, but it was still daylight at an altitude of 195 nautical miles. During the mission, the astronauts noted that the limb of the Earth displayed a more purplish tint instead of its normal blue. This effect, according to NASA scientists, is attributed to the high altitude residue (mostly sulfuric acid particles) from the Mount Pinatubo eruptions of mid June 1991. Note the broad band of twilight in the center of the image. This band is another indicator of the upper atmospheric scattering of sunlight caused by this layer of haze that exists between 20 and 30 kilometers above Earth. Sunlight highlights the empty payload bay (PLB), the vertical tail, and orbital maneuvering system (OMS) pods against the black

Chemotaxonomic phytoplankton patterns on the eastern boundary of the Atlantic Ocean

NASA Astrophysics Data System (ADS)

Barlow, R.; Gibberd, M.-J.; Lamont, T.; Aiken, J.; Holligan, P.

2016-05-01

Surface pigment data from a transect along the eastern boundary of the Atlantic Ocean was analysed using CHEMTAX to yield more detailed information on the composition of phytoplankton communities. Total chlorophyll a concentrations varied from 0.03 mg m-3 in a northern oligotrophic region to 30.3 mg m-3 in the Benguela ecosystem. Diatoms dominated the Benguela, while both diatoms and haptophytes were the major groups in the Canary ecosystem and the temperate NE Atlantic. Prochlorococcus was the most prominent group in the southern oligotrophic region (15.5°S-15°N) although haptophytes were also a significant component of the population. In contrast, haptophytes dominated the northern oligotrophic region (21°-40°N). Photo-pigment indices indicated that chlorophyll b was mainly associated with prasinophytes and chlorophyll c with diatoms. Elevated photosynthetic carotenoids were due to increased proportions of haptophytes, but also linked with diatoms and dinoflagellates. Photoprotective carotenoids were more prominently associated with Prochlorococcus and to a lesser extent to Synechococcus.

Late Quaternary carbonate accumulation along eastern South Atlantic Ocean

NASA Astrophysics Data System (ADS)

Crabill, K.; Slowey, N. C.; Foreman, A. D.; Charles, C.

2016-12-01

Water masses originating from both the North Atlantic Ocean and the Southern Ocean intersect the Walvis Ridge and Namibian margin of southwest Africa. Changes in the distribution and properties of these water masses through time are reflected by variations in the nature of the sediments accumulating along this margin. A suite of piston and gravity cores that possess sediment records corresponding to the most recent glacial-interglacial cycles were collected from the water depth range of 550 to 3700 meters. Sediment dry bulk density, XRF analyses and the concentration of CaCO3 were precisely determined at regular depth intervals in these cores. Foraminiferal δ18O along with XRF Fe/Ca data provide an age-depth model for key cores. The age-depth model and dry bulk density will be used with the calcium carbonate contents to calculate the accumulation rates of CaCO3 during each MIS 1-5e. The spatial and temporal variability in both the CaCO3 content and the CaCO3 mass accumulation rates along the Namibian continental slope will be described. Based on comparisons of these two parameters, inferences will be made about how variations of CaCO3 production, dilution of by non-CaCO3 sediment components, and dissolution of CaCO3 due to changes in ocean circulation/climate have occurred during intervals of the last glacial-interglacial cycle.

Sea surface salinity fronts in the Tropical Atlantic Ocean

NASA Astrophysics Data System (ADS)

Ruiz-Etcheverry, L.; Maximenko, N. A.; Melnichenko, O.

2016-12-01

Marine fronts are narrow boundaries that separate water masses of different properties. These fronts are caused by various forcing and believed to be an important component of the coupled ocean-atmosphere system, particularly in the tropical oceans. In this study, we use sea surface salinity (SSS) observations from Aquarius satellite to investigate the spatial structure and temporal variability of SSS fronts in the tropical Atlantic. A number of frontal features have been identified. The mean magnitude of the SSS gradient is maximum near the mouth of the Congo River (0.3-0.4 psu/100km). Relative maxima are also observed in the Inter Tropical Convergence Zone (ITCZ), the Gulf of Guinea, and the mouth of the Amazon River. The pattern of the magnitude of the SSS anomaly gradient revealed that the interaction between river plumes and saltier interior water is complex and highly variable during the three-year observation period. The variability of the magnitude of the density anomaly gradient computed from Aquarius SSS and Reynolds SST is also discussed. Images of the ocean color are utilized to trace the movement of the Congo and Amazon River plumes and compare them with the magnitude of the SSS gradient. Additionally, we analyze de circulation associated with the Amazon plume with altimetry data, and the vertical structure and its changes in time through Argo profiles.

Multilocus Bayesian Estimates of Intra-Oceanic Genetic Differentiation, Connectivity, and Admixture in Atlantic Swordfish (Xiphias gladius L.)

PubMed Central

Smith, Brad L.; Lu, Ching-Ping; García-Cortés, Blanca; Viñas, Jordi; Yeh, Shean-Ya; Alvarado Bremer, Jaime R.

2015-01-01

Previous genetic studies of Atlantic swordfish (Xiphias gladius L.) revealed significant differentiation among Mediterranean, North Atlantic and South Atlantic populations using both mitochondrial and nuclear DNA data. However, limitations in geographic sampling coverage, and the use of single loci, precluded an accurate placement of boundaries and of estimates of admixture. In this study, we present multilocus analyses of 26 single nucleotide polymorphisms (SNPs) within 10 nuclear genes to estimate population differentiation and admixture based on the characterization of 774 individuals representing North Atlantic, South Atlantic, and Mediterranean swordfish populations. Pairwise F ST values, AMOVA, PCoA, and Bayesian individual assignments support the differentiation of swordfish inhabiting these three basins, but not the current placement of the boundaries that separate them. Specifically, the range of the South Atlantic population extends beyond 5°N management boundary to 20°N-25°N from 45°W. Likewise the Mediterranean population extends beyond the current management boundary at the Strait of Gibraltar to approximately 10°W. Further, admixture zones, characterized by asymmetric contributions of adjacent populations within samples, are confined to the Northeast Atlantic. While South Atlantic and Mediterranean migrants were identified within these Northeast Atlantic admixture zones no North Atlantic migrants were identified respectively in these two neighboring basins. Owing to both, the characterization of larger number of loci and a more ample spatial sampling coverage, it was possible to provide a finer resolution of the boundaries separating Atlantic swordfish populations than previous studies. Finally, the patterns of population structure and admixture are discussed in the light of the reproductive biology, the known patterns of dispersal, and oceanographic features that may act as barriers to gene flow to Atlantic swordfish. PMID:26057382

Variability in mid-depth ventilation of the western Atlantic Ocean during the last deglaciation

NASA Astrophysics Data System (ADS)

Voigt, I.; Cruz, A. P. S.; Mulitza, S.; Chiessi, C. M.; Mackensen, A.; Lippold, J.; Antz, B.; Zabel, M.; Zhang, Y.; Barbosa, C. F.; Tisserand, A. A.

2017-09-01

Negative stable carbon isotopic excursions have been observed throughout most of the mid-depth ( 1000-3000 m) Atlantic Ocean during Heinrich Stadial 1 (HS1) and the Younger Dryas (YD). Although there is an agreement that these mid-depth excursions were in some way associated with a slowdown of the Atlantic Meridional Overturning Circulation (AMOC), there is still no consensus on the precise mechanism(s). Here we present benthic stable carbon and oxygen isotopic (δ13C and δ18O) records from five cores from the western equatorial Atlantic (WEA). Together with published benthic isotopic records from nearby cores, we produced a WEA depth transect ( 800-2500 m). We compare HS1 and YD data from this transect with data from previously published North and South Atlantic cores and demonstrate that the largest negative δ13C excursions occurred in the WEA during these times. Moreover, our benthic δ18O records require the presence of two water masses flowing from the Southern Ocean, bisected by a Northern Component Water (NCW). Given that δ18O is a conservative water mass tracer, we suggest that δ13C was decoupled from water mass composition and does not correspond to simple alternations between northern and southern sourced waters. Instead, δ13C behaved non-conservatively during HS1 and the YD. Consistently with our new 231Pa/230Th record from the WEA transect, that allowed the reconstruction of AMOC strength, we hypothesize that the negative δ13C excursions reflect an increase in the residence time of NCW in response to a weakened AMOC, allowing for a marked accumulation of 13C-depleted respired carbon at the mid-depth WEA.