Science.gov

Sample records for equatorial atlantic ocean

  1. 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.

  2. Interannual atmospheric variability forced by the deep equatorial Atlantic Ocean.

    PubMed

    Brandt, Peter; Funk, Andreas; Hormann, Verena; Dengler, Marcus; Greatbatch, Richard J; Toole, John M

    2011-05-26

    Climate variability in the tropical Atlantic Ocean is determined by large-scale ocean-atmosphere interactions, which particularly affect deep atmospheric convection over the ocean and surrounding continents. Apart from influences from the Pacific El Niño/Southern Oscillation and the North Atlantic Oscillation, the tropical Atlantic variability is thought to be dominated by two distinct ocean-atmosphere coupled modes of variability that are characterized by meridional and zonal sea-surface-temperature gradients and are mainly active on decadal and interannual timescales, respectively. Here we report evidence that the intrinsic ocean dynamics of the deep equatorial Atlantic can also affect sea surface temperature, wind and rainfall in the tropical Atlantic region and constitutes a 4.5-yr climate cycle. Specifically, vertically alternating deep zonal jets of short vertical wavelength with a period of about 4.5 yr and amplitudes of more than 10 cm s(-1) are observed, in the deep Atlantic, to propagate their energy upwards, towards the surface. They are linked, at the sea surface, to equatorial zonal current anomalies and eastern Atlantic temperature anomalies that have amplitudes of about 6 cm s(-1) and 0.4 °C, respectively, and are associated with distinct wind and rainfall patterns. Although deep jets are also observed in the Pacific and Indian oceans, only the Atlantic deep jets seem to oscillate on interannual timescales. Our knowledge of the persistence and regularity of these jets is limited by the availability of high-quality data. Despite this caveat, the oscillatory behaviour can still be used to improve predictions of sea surface temperature in the tropical Atlantic. Deep-jet generation and upward energy transmission through the Equatorial Undercurrent warrant further theoretical study.

  3. Layered basic complex in oceanic crust, romanche fracture, equatorial atlantic ocean.

    PubMed

    Melson, W G; Thompson, G

    1970-05-15

    A layered, basic igneous intrusion, analogous in mineralogy and texture to certain large, continental layered complexes, is exposed in the Romanche Fracture, equatorial Atlantic Ocean. Crustal intrusion of large masses of basic magmas with their subsequent gravity differentiation is probably one of a number of major processes involved in the formation of new oceanic crust during sea-floor spreading.

  4. Anthropogenic CO2 changes in the Equatorial Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Fajar, N. M.; Guallart, E. F.; Steinfeldt, R.; Ríos, A. F.; Pelegrí, J. L.; Pelejero, C.; Calvo, E.; Pérez, F. F.

    2015-05-01

    Methods based on CO2 and chlorofluorocarbon (CFC) data are used to describe and evaluate the anthropogenic CO2 (Cant) concentrations, Cant specific inventories, and Cant storage rates in the Equatorial Atlantic Ocean. The Cant variability in the water masses is evaluated from the comparison of two hydrographic sections along 7.5°N carried out in 1993 and 2010. During both cruises, high Cant concentrations are detected in the upper layers, with values decreasing progressively towards the deep layers. Overall, the Cant concentrations increase from 1993 to 2010, with a large increment in the upper North Atlantic Deep Water layer of about 0.18 ± 0.03 μmol kg-1 y-1. In 2010, the Cant inventory along the whole section amounts to 58.9 ± 2.2 and 45.1 ± 2.0 mol m-2 using CO2 and CFC based methods, respectively, with most Cant accumulating in the western basin. Considering the time elapsed between the two cruises, Cant storage rates of 1.01 ± 0.18 and 0.75 ± 0.17 mol m-2 y-1 (CO2 and CFC based methods, respectively) are obtained. Below ∼1000 m, these rates follow the pace expected from a progressive increase of Cant at steady state; above ∼1000 m, Cant increases faster, mainly due to the retreat of the Antarctic Intermediate Waters.

  5. Stacked jets in the deep equatorial Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Eden, Carsten; Dengler, Marcus

    2008-04-01

    Middepth current measurements in the equatorial Atlantic are characterized by elevated levels of energy contained in zonal flows of high baroclinic mode number. These alternating zonal flows, often called equatorial stacked jets, have amplitudes up to 20 cm s-1 and vertical wavelengths of 600 m. The jets are most pronounced in the depth range between 500 and 2500 m. Repeated direct velocity observations at 35°W indicate that the jets are coherent within ±1° of the equator. Individual jets can persist for 1-2 years, but they appear and decay rather irregularly. The equatorial stacked jets are also found in realistic general circulation model simulations. The features grow in amplitude with increasing horizontal and vertical model resolution. However, even at very high model resolutions, their amplitudes are still underestimated. In all model simulations, high levels of energy related to the stacked jets are found in the vicinity of the western boundary currents (WBCs). Depth range and strength of the WBCs in different experiments are related to depth range and strength of the jets. In the interior, stacked jets are characterized by eastward wave propagation suggesting that high baroclinic mode Kelvin waves radiate energy generated in the WBC into the interior and form the stacked jets.

  6. A New Starting point for the History of South and Equatorial Atlantic Oceans

    NASA Astrophysics Data System (ADS)

    Moulin, M.; Aslanian, D.; Olivet, J.; Labails, C.; Rabineau, M.

    2005-05-01

    The nature and genesis of the large, thinned transitional zone of the continental passive margins is still a matter of debate. Any further progress in that subject must imply an intregrated structural study of homologous margins, replaced in a very precise pre-opening kinematic reconstruction to constraint horizontal movements. In South and Equatorial Atlantic oceans, the pre-opening misfits problem has been already addressed by several authors and requires an assessment of rigidity of african and/or south american continental plates which border those oceans. Nevertheless the lack of magnetic anomalies, the pre-opening fit of the Equatorial Atlantic ocean is well constrained due to the presence of well-defined oceanic fracture zones, homologous Demerara and Guinea Plateaus, paralellism of the coasts and Kandi and Sobral continental lineations. This contraint compels us to resort to intraplate deformation to close the South Atlantic Ocean. Intregrating all continental deformations of both plates described in the litterature, we propose here the closest pre-opening fit for the Central part of the South Atlantic. This pre-opening fit leaves a large pre-drift thinned basin of several hundred kilometers which cannot be explained by any process which implies more horizontal movement (stretching, simple shear.). South of the Walvis-Rio Grande ridges, the pre-opening fit implies intraplate deformation in Paraña, Solado and Colorado basins (South America) as already suggested by Unternehr et al (1988) and Nürnberg & Müller (1991).

  7. Mercury Concentrations in Tuna (Thunnus albacares and Thunnus obesus) from the Brazilian Equatorial Atlantic Ocean.

    PubMed

    Lacerda, L D; Goyanna, F; Bezerra, M F; Silva, G B

    2017-02-01

    Average total Hg concentrations measured in muscle of two species of tuna (Thunnus obesus and T. albacares) captured in the Brazilian Equatorial Atlantic Ocean varied from 95 to 1748 ng.g(-1) wet weight in T. obesus and 48 to 500 ng.g(-1) wet weight in T. albacares. Higher concentrations in T. obesus are probably related to foraging on deep water carnivorous fish. Smaller individuals of both species showed the lowest concentrations, but a significant positive relationship between fish weight and length and Hg concentrations was found for T. obesus, but not for T. albacares. Largest individuals (>30 kg) of T. obesus showed Hg concentrations ≥1000 ng.g(-1), surpassing the legal limits for human consumption, although the average concentration for this species was much lower (545 ng.g(-1)). Concentrations in T. albacares from the Brazilian Equatorial were lower than those found in the African and in the North Atlantic. No comparison could be made for T. obesus due to few studies for this species in the Atlantic Ocean.

  8. Ucertainties of equatorial Atlantic seasonal cycles in an Ocean General Circulation Model induced by wind products during 1979-2001

    NASA Astrophysics Data System (ADS)

    Shi, Yanyan; Wang, Bin; Huang, Wenyu; Peng, Shuai; Dong, Fang

    2015-04-01

    Ocean models are very effective tools to analysis and quantify the ocean heat budget. However, the model performance largely depends on the choice of atmospheric forcing. In this study, 5 experiments are done to examine the sensitivity of the heat budget to wind forcing in equatorial Atlantic Ocean by using the OPA OGCM and LIM3 sea ice model. The wind forcing in the simulations are from 5 different reanalysis datasets during 1979-2001. In addition, the 5 experiments use exactly the same model configuration. The results show that equatorial eastern Atlantic is much more sensitive to wind forcing than equatorial western Atlantic in spite of the larger difference in winds above western Atlantic ocean. The maximum difference of temporal mean (1979-2001) SST among the 5 experiments in eastern Atlantic is as large as 0.7 °C while it is only 0.3 °C in western Atlantic. As for the differences of the 5 simulations in amplitude of SST seasonal cycle, they are also lager in eastern Atlantic and smaller in western Atlantic. Further analysis indicates that the larger differences existing in equatorial Atlantic is mainly due to the heat budget there, which is greatly affected by wind forcing. The largest different component of the heat budget comes from vertical mixing in the mixed layer in boreal summer. Moreover, the horizontal advection and net heat flux of the heat budget in each simulation are also affected by wind forcing, but they are smaller when compared with vertical mixing. In this situation, the contributions of each item (i.e. horizontal advection, net heat flux and vertical mixing) are different in all the simulations. Consider this study, we should be careful to choice wind forcing in equatorial eastern Atlantic study.

  9. Diagnosis of the tropical Atlantic near-equatorial SST bias in a directly coupled atmosphere-ocean general circulation model

    NASA Astrophysics Data System (ADS)

    DeWitt, David G.

    2005-01-01

    The current generation of non-flux-corrected coupled atmosphere-ocean general circulation models (CGCMs) have trouble correctly simulating the sign of the annual mean near-equatorial east to west gradient of sea surface temperature (SST) in the Atlantic Ocean. This model pathology is of concern because the distribution of tropical oceanic precipitation is related to the near-equatorial SST distribution. The tropical oceanic precipitation, in turn, influences local and remote precipitation over the tropical land areas through various teleconnection mechanisms. Therefore, understanding and eventually fixing this model error is of interest. In this study, the cause of the Atlantic equatorial SST gradient error in one CGCM is investigated using forced experiments with the CGCM ocean component model. These experiments show that the most likely candidate for this error is the too-weak zonal wind stress along the equator in the coupled model. This wind stress error affects the SST along the equator in two ways. First, it leads to a deepening of the thermocline in the eastern part of the basin and a shallowing in the western part. Second, the weak zonal stress leads to a vertical velocity distribution at the based of the mixed layer that is too weak in the eastern and central Atlantic and too strong in the western Atlantic. Both of these errors lead to insufficient cooling of the eastern near equatorial mixed layer and erroneously enhanced cooling in the western near equatorial mixed layer.

  10. Present-day transatlantic Saharan dust deposition across the equatorial North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Korte, Laura; Brummer, Geert-Jan; van der Does, Michelle; Guerreiro, Catarina; Hennekam, Rick; van Hateren, Johannes; Jong, Dirk; Munday, Chris; Schouten, Stefan; Jan-Berend, Stuut

    2017-04-01

    Massive amounts of Saharan dust are blown from the African coast across the Atlantic Ocean towards the Americas each year. This dust has direct and indirect effects on global climate including reflection and absorption of solar radiation as well as transport and deposition of nutrients and metals fertilizing both ocean and land. To determine the temporal and spatial variability of Saharan dust transport and deposition and their marine environmental effects across the equatorial North Atlantic Ocean, we have set up a monitoring experiment using deep-ocean sediment traps as well as on land-based dust collectors. The sediment traps were deployed at five sampling sites on a transect between northwest Africa and the Caribbean along 12⁰ N, in a down-wind extension of the land-based dust collectors placed at 19⁰ N on the Mauritanian coast in Iwik. We establish the temporal distribution of the particle fluxes deposited in the Atlantic and compare chemical compositions with the land-based dust collectors propagating to the down-wind sediment trap sites. First-year results show that the total mass fluxes in the ocean are highest at the sampling sites in the East and West, closest to the African continent and the Caribbean, respectively. Element ratios reveal that the lithogenic particles deposited nearest to Africa are most similar in composition to the Saharan dust collected in Iwik. Down-wind Al and Fe contents suggest a downwind change in the mineralogical composition of Saharan dust and indicate an increasing contribution of clay minerals towards the west. In the westernmost Atlantic, gradients suggest admixture of re-suspended clay-sized sediment advected towards the deep sediment trap. Seasonality is most prominent near both continents but generally weak, with mass fluxes dominated by calcium carbonate and clear seasonal maxima of biogenic silica towards the west. See also: www.nioz.nl/dust

  11. 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

  12. 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

  13. 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.

  14. THE ATMOSPHERIC CYCLING AND AIR-SEA EXCHANGE OF MERCURY SPECIES IN THE SOUTH AND EQUATORIAL ATLANTIC OCEAN. (R829796)

    EPA Science Inventory


    Measurements of gas-, particle- and precipitation-phases of atmospheric mercury
    (Hg) were made in the South and equatorial Atlantic Ocean as part of the 1996
    IOC Trace Metal Baseline Study (Montevideo, Uruguay to Barbados). Total gaseous
    mercury (TGM) ranged from ...

  15. THE ATMOSPHERIC CYCLING AND AIR-SEA EXCHANGE OF MERCURY SPECIES IN THE SOUTH AND EQUATORIAL ATLANTIC OCEAN. (R829796)

    EPA Science Inventory


    Measurements of gas-, particle- and precipitation-phases of atmospheric mercury
    (Hg) were made in the South and equatorial Atlantic Ocean as part of the 1996
    IOC Trace Metal Baseline Study (Montevideo, Uruguay to Barbados). Total gaseous
    mercury (TGM) ranged from ...

  16. 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

  17. Abyssal ostracods from the South and Equatorial Atlantic Ocean: Biological and paleoceanographic implications

    USGS Publications Warehouse

    Yasuhara, Moriaki; Cronin, T. M.; Martinez, Arbizu P.

    2008-01-01

    We report the distribution of ostracods from ???5000 m depth from the Southeast and Equatorial Atlantic Ocean recovered from the uppermost 10 cm of minimally disturbed sediments taken by multiple-corer during the R/V Meteor DIVA2 expedition M63.2. Five cores yielded the following major deep-sea genera: Krithe, Henryhowella, Poseidonamicus, Legitimocythere, Pseudobosquetina, and Pennyella. All genera are widely distributed in abyssal depths in the world's oceans and common in Cenozoic deep-sea sediments. The total number of ostracod specimens is higher and ostracod shell preservation is better near the sediment-water interface, especially at the 0-1 cm core depths. Core slices from ???5 to 10 cm were barren or yielded a few poorly preserved specimens. The DIVA2 cores show that deep-sea ostracod species inhabit corrosive bottom water near the carbonate compensation depth (CCD) even though their calcareous valves are rarely preserved as fossils in sediment cores due to postmortem dissolution. Their occurrence at great water depths may partially explain the well-known global distributions of major deep-sea taxa in the world's oceans, although further expeditions using minimal-disturbance sampling devices are needed to fill geographic gaps. ?? 2008 Elsevier Ltd. All rights reserved.

  18. Revisiting the Ceara Rise, equatorial Atlantic Ocean: isotope stratigraphy of ODP Leg 154

    NASA Astrophysics Data System (ADS)

    Wilkens, Roy; Drury, Anna Joy; Westerhold, Thomas; Lyle, Mitchell; Gorgas, Thomas; Tian, Jun

    2017-04-01

    Isotope stratigraphy has become the method of choice for investigating both past ocean temperatures and global ice volume. Lisiecki and Raymo (2005) published a stacked record of 57 globally distributed benthic δ18O records versus age (LR04 stack). In this study LR04 is compared to high resolution records collected at all of the sites drilled during Ocean Drilling Program (ODP) Leg 154 on the Ceara Rise, in the western equatorial Atlantic Ocean. Newly developed software - the Code for Ocean Drilling Data (CODD) - is used to check data splices of the Ceara sites and better align out-of-splice data with in-splice data. CODD allows to depth and age scaled core images recovered from core table photos enormously facilitating data analysis. The entire splices of ODP Sites 925, 926, 927, 928 and 929 were reviewed. Most changes were minor although several large enough to affect age models based on orbital tuning. We revised the astronomically tuned age model for the Ceara Rise by tuning darker, more clay rich layers to Northern Hemisphere insolation minima. Then we assembled a regional composite benthic stable isotope record from published data. This new Ceara Rise stack provides a new regional reference section for the equatorial Atlantic covering the last 5 million years with an independent age model compared to the non-linear ice volume models of the LR04 stack. Comparison shows that the benthic δ18O composite is consistent with the LR04 stack from 0 - 4 Ma despite a short interval between 1.80 and 1.90 Ma, where LR04 exhibits 2 maxima but where Ceara Rise contains only 1. The interval between 4.0 and 4.5 Ma in the Ceara Rise compilation is decidedly different from LR04, reflecting both the low amplitude of the signal over this interval and the limited amount of data available for the LR04 stack. Our results also point out that precession cycles have been misinterpreted as obliquity in the LR04 stack as suggested by the Ceara Rise composite at 4.2 Ma.

  19. An Early Cenozoic Ichthyolith Record from Demerara Rise (ODP Site 1258: Equatorial Atlantic Ocean)

    NASA Astrophysics Data System (ADS)

    Bryant, R. M.; Sibert, E. C.; Norris, R. D.

    2014-12-01

    Peak global warmth during the early Eocene is a partial analog to the future structure of marine ecosystems in a high pCO2 world. Early Eocene oceans are generally regarded as supporting warmer oceans with lower overall productivity than today owing to the low concentrations of preserved organic matter in pelagic sediments. It has also been proposed that Eocene oceans were about as productive as now, but higher respiration rates in a warmer-than-modern ocean more efficiently recycled organic matter and nutrients. We investigated Eocene export productivity and its link to taxonomic diversity using the pelagic ichthyolith record. Ichthyoliths are calcium phosphate microfossils including fish teeth and shark denticles and their fragments, and are a unique paleoceanographic proxy because they represent a fossil record for marine vertebrates, a charismatic and tangible part of the ecosystem that generally goes unrepresented in the fossil record. Analysis of the ichthyolith record in Ocean Drilling Program Site 1258 (NE South America) shows a remarkable increase in accumulation rate of ichthyoliths from the Paleocene into the Eocene, suggesting that onset of the Early Eocene Climatic Optimum in the equatorial Atlantic was favorable to fish production. Our results suggest that, if anything, the early Eocene maintained higher productivity than in the late Paleocene. These results compare favorably with a record of ichthyolith accumulation in the South Pacific (DSDP 596), which also indicates unusually high rates of fish productivity in the peak of Eocene warm climates. Low resolution data sets from the Pacific suggest an explosion of morphotypes during the warm period associated with an increase in ichthyolith mass accumulation rates. Peak global warmth, therefore, appears to be associated with both higher fish production and higher taxonomic diversity than suggested by previous reconstructions of Eocene primary production. Increasing the amount of continuous records of

  20. A synthesis of the first GARP Globa Experiment (FGGE) in the equatorial Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Molinari, R. L.; Garzoli, S. L.; Katz, E. J.; Harrison, D. E.; Richardson, P. L.; Reverdin, G.

    A synthesis of near-surface oceanographic and surface meteorological data collected during the First GARP Global Experiment, FGGE, is presented to portray the oceanic response to the seasonal wind forcing for the period December 1978 to November 1979, inclusive. Major wind events during FGGE are in phase with events given in climatology. In particular, the February-March-April relaxation and May enhancement of equatorial winds occurs within one month of the mean event. Accordingly, the oceanic responses, such as the May, June, July appearance of an equatorial cold water tongue, the acceleration of the South Equatorial Current (SEC) and the vertical displacement of the equatorial thermocline occur at the average time. Furthermore, the curl distribution in the vicinity of the North Equatorial Countercurrent (NECC) during 1979 is similar to the climatological distribution in terms of phase and amplitude, except for a westward displacement in the position of the maximum curl. As predicted from linear theory, the 1979 thermocline response across the NECC is in phase with the climatological response with a westward displacement of the maximum thermocline movement. Deeper than average equatorial thermoclines and a weaker SEC may, in part, be responsible for the anomalously warm sea-surface temperatures observed on the equator between 10°W and 30°W from June to November.

  1. Metagenomic analysis of sediments under seaports influence in the Equatorial Atlantic Ocean.

    PubMed

    Tavares, Tallita Cruz Lopes; Normando, Leonardo Ribeiro Oliveira; de Vasconcelos, Ana Tereza Ribeiro; Gerber, Alexandra Lehmkuhl; Agnez-Lima, Lucymara Fassarella; Melo, Vânia Maria Maciel

    2016-07-01

    Maritime ports are anthropogenic interventions capable of causing serious alterations in coastal ecosystems. In this study, we examined the benthic microbial diversity and community structure under the influence of two maritime ports, Mucuripe (MUC) and Pecém (PEC), at Equatorial Atlantic Ocean in Northeast Brazil. Those seaports differ in architecture, time of functioning, cargo handling and contamination. The microbiomes from MUC and PEC were also compared in silico to 11 other globally distributed marine microbiomes. The comparative analysis of operational taxonomic units (OTUs) retrieved by PCR-DGGE showed that MUC presents greater richness and β diversity of Bacteria and Archaea than PEC. In line with these results, metagenomic analysis showed that MUC and PEC benthic microbial communities share the main common bacterial phyla found in coastal environments, although can be distinguish by greater abundance of Cyanobacteria in MUC and Deltaproteobacteria in PEC. Both ports differed in Archaea composition, being PEC port sediments dominated by Thaumarchaeota. The microbiomes showed little divergence in their potential metabolic pathways, although shifts on the microbial taxonomic signatures involved in nitrogen and sulphur metabolic pathways were observed. The comparative analysis of different benthic marine metagenomes from Brazil, Australia and Mexico grouped them by the geographic location rather than by the type of ecosystem, although at phylum level seaport sediments share a core microbiome constituted by Proteobacteria, Cyanobacteria, Actinobacteria, Tenericuteres, Firmicutes, Bacteriodetes and Euryarchaeota. Our results suggest that multiple physical and chemical factors acting on sediments as a result of at least 60years of port operation play a role in shaping the benthic microbial communities at taxonomic level, but not at functional level.

  2. Revisiting the Ceara Rise, equatorial Atlantic Ocean: isotope stratigraphy of ODP Leg 154 from 0 to 5 Ma

    NASA Astrophysics Data System (ADS)

    Wilkens, Roy H.; Westerhold, Thomas; Drury, Anna J.; Lyle, Mitchell; Gorgas, Thomas; Tian, Jun

    2017-07-01

    Isotope stratigraphy has become the method of choice for investigating both past ocean temperatures and global ice volume. Lisiecki and Raymo (2005) published a stacked record of 57 globally distributed benthic δ18O records versus age (LR04 stack). In this study LR04 is compared to high-resolution records collected at all of the sites drilled during ODP Leg 154 on the Ceara Rise, in the western equatorial Atlantic Ocean. Newly developed software is used to check data splices of the Ceara Rise sites and better align out-of-splice data with in-splice data. Core images recovered from core table photos are depth and age scaled and greatly assist in the data analysis. The entire splices of ODP sites 925, 926, 927, 928 and 929 were reviewed. Most changes were minor although several were large enough to affect age models based on orbital tuning. A Ceara Rise composite record of benthic δ18O is out of sync with LR04 between 1.80 and 1.90 Ma, where LR04 exhibits two maxima but Ceara Rise data contain only one. The interval between 4.0 and 4.5 Ma in the Ceara Rise compilation is decidedly different from LR04, reflecting both the low amplitude of the signal over this interval and the limited amount of data available for the LR04 stack. A regional difference in benthic δ18O of 0.2 ‰ relative to LR04 was found. Independent tuning of Site 926 images and physical property data to the Laskar et al. (2004) orbital solution and integration of available benthic stable isotope data from the Ceara Rise provides a new regional reference section for the equatorial Atlantic covering the last 5 million years.

  3. The atmospheric cycling and air-sea exchange of mercury species in the South and equatorial Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Lamborg, C. H.; Rolfhus, K. R.; Fitzgerald, W. F.; Kim, G.

    Measurements of gas-, particle- and precipitation-phases of atmospheric mercury (Hg) were made in the South and equatorial Atlantic Ocean as part of the 1996 IOC Trace Metal Baseline Study (Montevideo, Uruguay to Barbados). Total gaseous mercury (TGM) ranged from 1.17 to 1.99 ng m -3, with a weighted mean of 1.61±0.09 ng m -3. These values compare well with Pacific Ocean data and earlier results from the Atlantic. The open-ocean samples recorded a distinctive inter-hemispheric gradient, which is consistent with a long-lived trace gas emitted to a greater extent from the Northern than from the Southern Hemisphere. Correlations with surface 222Rn measurements indicate an influence of regional terrestrial sources on open-ocean TGM concentrations. Total Hg in precipitation ranged from 10 to 99 pM (volume-weighted average: 17.8±2.9 pM). On average, about 72% of the total Hg was "reactive" (i.e., reducible by SnCl 2). The data showed an apparent rapid nonlinear decrease in concentration with event size ("washout curve"). The wet depositional flux was estimated at 18-36 nmol m -2 yr -1 (4-7 μg m -2 yr -1), which is slightly lower than that found in mid-continental locations of North America (6-12 μg m -2 yr -1). 210Pb analyses indicate a strong impact of particles on rain Hg concentrations. Particle-phase Hg (range 5-25 fmol m -3; mean 12±1 fmol m -3; 66% "reactive") was comparable to values over the equatorial Pacific. The dry depositional flux is ca. 0.4 nmol m -2 yr -1, or 0.4-1.0% of the wet flux. Particle-phase Hg concentrations did not change significantly when African dust was present during sampling. However, the Hg/Al ratios were consistent with crustal values during the dust periods. The residence time of TGM was calculated to be 1.3-3.4 yr in this region, based on standing stock estimates. Incubation of rainwater added to surface seawater gave reduction rates [i.e., production of elemental Hg (Hg°); 1.6-4.3% d of total Hg added] comparable to additions of

  4. Vulnerability to longline fisheries of three hammerhead shark Sphyrna species in the south-western and equatorial Atlantic Ocean.

    PubMed

    Bezerra, N P A; Travassos, P; Hazin, F H V

    2016-08-01

    Catch and effort data from 29 418 longline sets from Brazilian tuna longline vessels operating in the south-western and equatorial Atlantic Ocean between 2004 and 2011 were analysed to investigate the distribution, catch rate and size of three species of hammerhead sharks (Sphyrna lewini, Sphyrna mokarran and Sphyrna zygaena). During that period, 6172 hammerhead sharks were caught. Among the elasmobranchs, the highest percentage of hammerhead sharks were caught in 2007, when they accounted for 3·90% of the group, while the lowest value of 0·40% was recorded in 2010. In general, the spatial distribution of the mean catch per unit effort (CPUE) by years and quarters showed a trend of higher catches near the equatorial region and in southern Brazil. The nominal mean CPUE was 0·12 Sphyrna spp. 1000(-1) hooks, with the highest value being recorded in 2007 (0·30 Sphyrna spp. 1000(-1) hooks). The standardized yearly CPUE estimated by a generalized linear model assuming a zero inflated negative binomial (ZINB) distribution were not much different from nominal values. Of the 205 sexed specimens, 117 were females and 88 were males, resulting in a sex ratio with a predominance of females (1·30:1·00), although not statistically significant. The total length of females ranged from 1200 to 2800 mm and of males from 1100 to 3100 mm. Juvenile hammerhead sharks represented 82 and 54% of the sexed female and male specimens, respectively.

  5. New dense-grid aeromagnetic map of Gulf of Guinea cul-de-sac, northeastern equatorial Atlantic Ocean

    SciTech Connect

    Babalola, O.O.

    1985-02-01

    As part of a major project to procure miscellaneous geophysical coverage of the entire country, the Geological Survey of Nigeria has acquired aeromagnetic data, presented as contour maps at various scales, over the nation's 7 sedimentary basins. The coverage over the Nigerian continental margin, acquired at 2500 ft above sea level, was flown at 4-km flight-line spacing in a north-northeasterly direction and at 20-km tie-line spacing in a west-northwesterly direction. Another tie line was flown along the coastline. Twenty 1:250,000 one-degree square, total intensity aeromagnetic contour maps covering the marginal basins down to the shelf break were assembled into a single aeromagnetic map of the Gulf of Guinea cul-desac. The map area lies within lat. 3/sup 0/-8/sup 0/N, and long. 2/sup 0/-9/sup 0/E. It covers the Nigerian portion of the Dahomey embayment, the Anambra and Niger delta basins, and the southern portion of the Benue rift. The map covers the location of the postulated Late Cretaceous triple junction involving the Benue Trough aulacogen, the northward-propagating South Atlantic, and the transform-dominated Equatorial Atlantic. In addition to the region seaward of the continental shelf, the map covers the Niger Delta basin, the basement of which is also inferred to consist mainly of oceanic crust prograded by the thick sediments of the Tertiary Niger delta. This areas is also the location of the Late Cretaceous coalescence of the North Atlantic and South Atlantic spreading systems hitherto separate from one another. This new aeromagnetic map fills an important data gap (due to proprietary restrictions and acquisition difficulties) in previous studies of this oil-prolific and geologically unique province. The map would be useful in future structural and tectonics studies of the Gulf of Guinea cul-de-sac.

  6. How predictable are equatorial Atlantic surface winds?

    NASA Astrophysics Data System (ADS)

    Richter, Ingo; Doi, Takeshi; Behera, Swadhin

    2017-04-01

    Sensitivity tests with the SINTEX-F general circulation model (GCM) as well as experiments from the Coupled Model Intercomparison Project phase 5 (CMIP5) are used to examine the extent to which sea-surface temperature (SST) anomalies contribute to the variability and predictability of monthly mean surface winds in the equatorial Atlantic. In the SINTEX-F experiments, a control experiment with prescribed observed SST for the period 1982-2014 is modified by inserting climatological values in certain regions, thereby eliminating SST anomalies. When SSTs are set to climatology in the tropical Atlantic only (30S to 30N), surface wind variability over the equatorial Atlantic (5S-5N) decreases by about 40% in April-May-June (AMJ). This suggests that about 60% of surface wind variability is due to either internal atmospheric variability or SSTs anomalies outside the tropical Atlantic. A further experiment with climatological SSTs in the equatorial Pacific indicates that another 10% of variability in AMJ may be due to remote influences from that basin. Experiments from the CMIP5 archive, in which climatological SSTs are prescribed globally, tend to confirm the results from SINTEX-F but show a wide spread. In some models, the equatorial Atlantic surface wind variability decreases by more than 90%, while in others it even increases. Overall, the results suggest that about 50-60% of surface wind variance in AMJ is predictable, while the rest is due to internal atmospheric variability. Other months show significantly lower predictability. The relatively strong internal variability as well as the influence of remote SSTs suggest a limited role for coupled ocean-atmosphere feedbacks in equatorial Atlantic variability.

  7. Whale Shark (Rhincodon typus) Seasonal Occurrence, Abundance and Demographic Structure in the Mid-Equatorial Atlantic Ocean

    PubMed Central

    Hazin, Fábio H. V.

    2016-01-01

    Whale sharks are generally associated with environmental factors that drive their movements to specific locations where food availability is high. Consequently, foraging is believed to be the main reason for the formation of whale shark aggregations. Feeding aggregations occur mainly in nearshore areas and are composed primarily of immature individuals. Conversely, aggregations of mature adults are rarely observed, and their occurrence is correlated with oceanic environments. Despite an increase in the number of whale shark studies, information on mating and parturition grounds is still lacking. In the present work, we assessed the ecological and behavioural aspects of the whale sharks that visit the archipelago of São Pedro and São Paulo (ASPSP), located ~1,000 km off the coast of Brazil in the equatorial Atlantic Ocean. Forty-nine whale sharks were recorded from February 2005 to May 2014. The estimated mean ± SD size was 8.27 ± 2.52 m (range: 2.5–14.0 m) with no significant differences in size across the year. The maturational stages were classified by size as immature (<8.0 m; 32.56%) and mature (>9.0 m; 46.51%); with almost half of the observed animals being mature specimens. The majority of sightings occurred between February and June. During this period, the ocean current weakens and the waters are enriched by eggs and larvae of fishes and invertebrates that attract marine life to forage. At the same time, evidence of reproductive activity in adult females (i.e. swollen abdomen and bite marks on the pectoral fins), and the potential mating behaviour exhibited by one male, suggest that the ASPSP area might also have a role in whale shark reproduction. Irrespective of its use for feeding or reproduction, this insular habitat serves as a meeting point for both juvenile and adult whale sharks, and may play an important ecological role for the species. PMID:27783634

  8. Whale Shark (Rhincodon typus) Seasonal Occurrence, Abundance and Demographic Structure in the Mid-Equatorial Atlantic Ocean.

    PubMed

    Macena, Bruno C L; Hazin, Fábio H V

    2016-01-01

    Whale sharks are generally associated with environmental factors that drive their movements to specific locations where food availability is high. Consequently, foraging is believed to be the main reason for the formation of whale shark aggregations. Feeding aggregations occur mainly in nearshore areas and are composed primarily of immature individuals. Conversely, aggregations of mature adults are rarely observed, and their occurrence is correlated with oceanic environments. Despite an increase in the number of whale shark studies, information on mating and parturition grounds is still lacking. In the present work, we assessed the ecological and behavioural aspects of the whale sharks that visit the archipelago of São Pedro and São Paulo (ASPSP), located ~1,000 km off the coast of Brazil in the equatorial Atlantic Ocean. Forty-nine whale sharks were recorded from February 2005 to May 2014. The estimated mean ± SD size was 8.27 ± 2.52 m (range: 2.5-14.0 m) with no significant differences in size across the year. The maturational stages were classified by size as immature (<8.0 m; 32.56%) and mature (>9.0 m; 46.51%); with almost half of the observed animals being mature specimens. The majority of sightings occurred between February and June. During this period, the ocean current weakens and the waters are enriched by eggs and larvae of fishes and invertebrates that attract marine life to forage. At the same time, evidence of reproductive activity in adult females (i.e. swollen abdomen and bite marks on the pectoral fins), and the potential mating behaviour exhibited by one male, suggest that the ASPSP area might also have a role in whale shark reproduction. Irrespective of its use for feeding or reproduction, this insular habitat serves as a meeting point for both juvenile and adult whale sharks, and may play an important ecological role for the species.

  9. Prokaryoplankton standing stocks in oligotrophic gyre and equatorial provinces of the Atlantic Ocean: Evaluation of inter-annual variability

    NASA Astrophysics Data System (ADS)

    Heywood, J. L.; Zubkov, M. V.; Tarran, G. A.; Fuchs, B. M.; Holligan, P. M.

    2006-07-01

    Temporal changes of prokaryoplankton in three different provinces of the Atlantic Ocean were examined between 1996 and 2004. The abundance and integrated biomass of three prokaryote groups ( Prochlorococcus spp. , Synechococcus spp. and other prokaryoplankton) were used to detect standing stock changes in the northern and southern oligotrophic gyres and in the equatorial region. Mean cell concentrations (±standard error of the mean) of Prochlorococcus spp., Synechococcus spp. and other prokaryoplankton above the nitracline in the northern oligotrophic gyre were 1.2×10 5 (±0.08), 5.0×10 3 (±1.22) and 0.9×10 6 (±0.03) cells mL -1, respectively. Similar concentrations of 1.2×10 5 (±0.06) Prochlorococcus mL -1, 1.9×10 3 (±0.29) Synechococcus mL -1 and 0.7×10 6 (±0.03) other prokaryoplankton mL -1 were measured in the southern oligotrophic gyre, with higher concentrations of all prokaryote groups in equatorial waters. Integrated biomass (±standard error of the mean) of Prochlorococcus spp. above the nitracline was 173 (±21) mg C m -2 in the northern oligotrophic gyre, 190 (±14) mg C m -2 in the southern oligotrophic gyre and 141 (±15) mg C m -2 in the equatorial region. Synechococcus spp. biomass was lower in each of the three provinces (18 (±2), 17 (±4) and 32 (±5) mg C m -2, respectively). The data showed no statistically significant inter-annual variability in Prochlorococcus or Synechococcus abundance or integrated biomass above the nitracline in any of the provinces. The abundance and biomass of the remaining prokaryoplankton were variable, but these variations could not be ascribed to seasonal differences and did not follow a clear inter-annual trend. In light of results presented here, recommendations on the frequency and spatial resolution of sampling needed to characterise province-scale temporal variability of prokaryoplankton communities have been suggested.

  10. Seasonal influence of ENSO on the Atlantic ITCZ and equatorial South America

    NASA Astrophysics Data System (ADS)

    Münnich, M.; Neelin, J. D.

    2005-11-01

    In late boreal spring, especially May, a strong relationship exists in observations among precipitation anomalies over equatorial South America and the Atlantic intertropical convergence zone (ITCZ), and eastern equatorial Pacific and central equatorial Atlantic sea surface temperature anomalies (SSTA). A chain of correlations of equatorial Pacific SSTA, western equatorial Atlantic wind stress (WEA), equatorial Atlantic SSTA, sea surface height, and precipitation supports a causal chain in which El Niño/Southern Oscillation (ENSO) induces WEA stress anomalies, which in turn affect Atlantic equatorial ocean dynamics. These correlations show strong seasonality, apparently arising within the atmospheric links of the chain. This pathway and the influence of equatorial Atlantic SSTA on South American rainfall in May appear independent of that of the northern tropical Atlantic. Brazil's Nordeste is affected by the northern tropical Atlantic. The equatorial influence lies further to the north over the eastern Amazon and the Guiana Highlands.

  11. Equatorial Wave Line, Pacific Ocean

    NASA Technical Reports Server (NTRS)

    1993-01-01

    This Equatorial Wave Line (2.0 N, 102.5W) seen in the Pacific Ocean is of great interest to oceanographers because of the twice annual upwelling of the oceans nutrients. As a result of nearly constant easterly winds, cool nutrient rich water wells up at the equator. The long narrow line is an equatorial front or boundry between warm surface equatorial water and cool recently upwelled water as the intermix of nutrients takes place.

  12. Seismic Reflection Image of the Lithosphere-Asthenosphere Boundary across the Equatorial Fracture Zones in the Atlantic Ocean.

    NASA Astrophysics Data System (ADS)

    Mehouachi, F.; Singh, S. C.

    2016-12-01

    The Lithosphere-Astenopshere Boundary (LAB) is one of the most extensive plate boundaries in Earth, but its detection have been very elusive because of the aseismic nature of the differential motion between the lithosphere and the underlying astenopshere. The LAB has been identified using surface waves and receiver function methods, but their vertical resolutions are of the order 30 km and 10 km, respectively. Here we use seismic reflection method to image the LAB. In order to image such a deep structure, we have used a 12 km long multi-component streamer deployed at 30 m water depth, deepest streamer ever used, and 10,000 cubic inch tuned air-gun source, for recording and generating low frequency energy from deep earth, respectively. A 800 km long seismic reflection profile was shot across three major transform fault and fracture zones in the equatorial Atlantic Ocean, namely Romanche, St Paul and Chain. The age contrasts along our profile are: 25 Ma to 10 Ma across the Chain Fracture Zone (FZ), 10 Ma to 40 Ma across the Romanche Transform Fault (TF), and 40 Ma to 70 Ma across the St Paul FZ. We find that the LAB reflection across the St Paul FZ lies at 70 km (40 Ma) and 80 km (70 Ma) depth, consistent with the age-dependent depth of the LAB. We also image a second reflection at 15 km and 10 km below the LAB reflection across the FZ, possibly defining a channel above the asthenosphere. The thinning of this channel LAB across the St Paul FZ suggests that the channel thickness decreases due to the cooling of the lithosphere, indicative of the presence of hot fluid in the channel.

  13. Influence of the reduction of the incoming raditaion over the Atlantic Southern Ocean on the simulation of the tropical Atlantic variability and its impacts on the equatorial Pacific.

    NASA Astrophysics Data System (ADS)

    Losada, Teresa; Rodríguez-Fonseca, Belén; Castaño-Tierno, Antonio; Mohino, Elsa; Mechoso, C. Roberto

    2017-04-01

    Coupled global climate models (CGCMs) show important biases in the simulation of SST, not only in the tropics, but also over the Southern Ocean. A recent work has shown that improving the errors in the Southern Ocean SST can result in a improvement of the tropical biases in the UCLA CGCM. In this work, we analyse how this model simulates the tropical Atlantic Niño mode in a control run and we compare the results with the variability of a second simulation in which we apply an idealized reduction of the incoming shortwave radiation over the Atlantic sector of the Southern Ocean. Our results show an improvement of the simulation of the tropical Atlantic variability at interannual timescales in the idealized simulation. The representation of the interbasin tropical teleconnection between Atlantic and Pacific Niños is also improved, with a realistic representation of its multidecadal variability.

  14. Role of the Interannual equatorial Kelvin wave propagations in the equatorial Atlantic on the Angola Benguela current system.

    NASA Astrophysics Data System (ADS)

    Anicet Imbol Koungue, Rodrigue; Illig, Serena; Rouault, Mathieu

    2017-04-01

    The link between equatorial Atlantic Ocean variability and the coastal region of Angola and Namibia is investigated at interannual time scales from 1998 to 2012. An index of the equatorial Kelvin wave activity is defined based on equatorial PIRATA in situ data. Results show a significant correlation between monthly dynamic height anomalies derived from the Prediction and Research Moored Array in the Tropical Atlantic (PIRATA), monthly Sea Surface Height anomalies (SSHA) derived from altimetry and SSHA calculated with an Ocean Linear Model. This allows interpreting PIRATA record into equatorial Kelvin wave signal. Estimated phase speed of eastward propagations from PIRATA equatorial mooring remains in agreement with the linear theory, emphasizing the dominance of the second baroclinic mode. Systematic analysis of all strong interannual equatorial SSH anomalies shows that they precede by one month extreme interannual SST anomalies along the African coast, suggesting that major warm and cold events in the Angola-Benguela current system are remotely forced by ocean atmosphere interactions in the equatorial Atlantic. Wave dynamics along the equatorial wave guide, as inferred from the Ocean Linear Model, is at the origin of their developments. Wind anomalies in the Western Equatorial Atlantic force equatorial downwelling and upwelling Kelvin waves that propagate eastward along the equator and then polewards along the African coast triggering extreme warm and cold events respectively. A proxy index based on linear ocean dynamics appears to be significantly more skilful in forecasting coastal variability than an index based on wind variability.

  15. Equatorial Wave Line, Pacific Ocean

    NASA Image and Video Library

    1993-01-19

    STS054-95-042 (13-19 Jan 1993) --- The Equatorial Pacific Ocean is represented in this 70mm view. The international oceanographic research community is presently conducting a program called Joint Global Ocean Flux Study (JGOFS) to study the global ocean carbon budget. A considerable amount of effort within this program is presently being focused on the Equatorial Pacific Ocean because of the high annual average biological productivity. The high productivity is the result of nearly constant easterly winds causing cool, nutrient-rich water to well up at the equator. In this view of the sun glint pattern was photographed at about 2 degrees north latitude, 103 degrees west longitude, as the Space Shuttle passed over the Equatorial Pacific. The long narrow line is the equatorial front, which defines the boundary between warm surface equatorial water and cool, recently upwelled water. Such features are of interest to the JGOFS researchers and it is anticipated that photographs such as this will benefit the JGOFS program.

  16. Deep Equatorial Atlantic Ocean Circulation over the Last 25,000 Years - Insights from 231Pa/230Th, 14C and Sortable Silt Grain Size

    NASA Astrophysics Data System (ADS)

    Ng, H. C.; Robinson, L. F.; McManus, J. F.; Mohamed Falcon, K. J.; Jacobel, A. W.

    2014-12-01

    Evidence points to a key role of the Atlantic circulation in controlling climate changes during the last deglacial (20-10 ka), though quantifying the rate of past ocean circulation remains an open challenge. Existing Atlantic rate proxy records over the last deglacial exhibit pronounced differences both in timing and magnitudes at both deep and intermediate depths. This uncertainty calls for more rate proxy data at key sites to improve understanding of the driving mechanisms behind the Atlantic observations. This study examines three complementary rate proxies (231Pa/230Th, Δ14C and sortable silt grain size) of Equatorial Atlantic sediment cores from 2.7 to 4.1 km depth from the east and west of the Mid-Atlantic Ridge. Sediment cores from the Ceara Rise in the western basin (4.1 km depth; 3.3 km depth) support a picture of relatively 14C-depleted deep water with higher Pa/Th values during the Last Glacial Maximum compared to the modern day. During Heinrich Stadial 1, there is a marked increase in Pa/Th values. Measured opal fluxes indicate that opal scavenging is not the main driver of the observed Pa/Th changes. At the same time, radiocarbon data indicate that the most 14C-depleted signature occurs at around 3 km water depth. Sortable silt mean size also shows distinctive changes around this period, but with some offset in timing potentially related to changes in circulation rate at different scales. Results from two new cores collected on a recent cruise (JC094) will be used to extend our understanding of these Equatorial Atlantic glacial-deglacial rate proxy dynamics and their relative timings. Both cores were collected far from the continental margin, in the central and eastern Atlantic (7o26.10'N, 21o47.78'W, 3.4 km depth; 15o27.86'N, 50o59.49'W, 2.7 km depth) providing a synoptic basin scale view of these important rate tracers in the Atlantic.

  17. Seasonal to decadal variations of sea surface pCO2 and sea-air CO2 flux in the equatorial oceans over 1984-2013: A basin-scale comparison of the Pacific and Atlantic Oceans

    NASA Astrophysics Data System (ADS)

    Wang, Xiujun; Murtugudde, Raghu; Hackert, Eric; Wang, Jing; Beauchamp, Jim

    2015-05-01

    The equatorial Pacific and Atlantic Oceans release significant amount of CO2 each year. Not much attention has been paid to evaluating the similarities and differences between these two basins in terms of temporal variability. Here we employ a basin-scale, fully coupled physical-biogeochemical model to study the spatial and temporal variations in sea surface pCO2 and air-sea CO2 flux over the period of 1984-2013 in the equatorial Pacific and Atlantic Oceans. The model reproduces the overall spatial and temporal variations in the carbon fields for both basins, including higher values to the south of the equator than to the north, the annual maximum sea surface pCO2 in boreal spring, and the annual peak in sea-to-air CO2 flux in boreal fall in the upwelling regions. The equatorial Pacific reveals a large interannual variability in sea surface pCO2, which is associated with the El Niño-Southern Oscillation. As a contrast, there is a strong seasonality but little interannual variability in the carbon fields of the equatorial Atlantic. The former is driven by the variability of dissolved inorganic carbon but the latter by sea surface temperature. Our model estimates an average sea-to-air CO2 flux of 0.521 ± 0.204 Pg C yr-1 for the tropical Pacific (18°S-18°N, 150°E-90°W), which is in good agreement with the observation-based estimate (0.51 ± 0.24 Pg C yr-1). On average, sea-to-air CO2 flux is 0.214 ± 0.03 Pg C yr-1 in the tropical Atlantic (10°S-10°N), which compares favorably with observational estimates.

  18. Vertical transport of steroid alcohols and ketones measured in a sediment trap experiment in the equatorial Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Gagosian, Robert B.; Smith, Steven O.; Nigrelli, Gale E.

    1982-07-01

    The vertical flux and free steroid alcohol (sterol) and ketone composition of particulate material was determined using sediment traps deployed at 389, 988, 3755 and 5068 m at a station in the equatorial North Atlantic, PARFLUX E. Cholest-5-en-3β-ol (cholesterol) was found to be the dominant sterol in all the traps. This compound had a maximum flux at 988 m, accounting for more than 90% of the sterols at this depth. Inputs from mesopelagic Zooplankton populations living in or migrating to depths between the 389 and 988 m traps appear to be responsible for this distribution. The deeper two traps exhibited an increased flux of phytosterols relative to cholesterol, probably due to (a) the incorporation of labile phytoplankton remains in fecal pellets and rapid transport into the deep sea and (b) differential dissolution of heterogeneous large particles. A maximum of 5-22% of the sterols produced in the euphotic zone were present in the 389 m trap. This value drops to less than 1% for the 5068 m trap, 200 m above the sediment surface. In general steroid ketone fluxes gradually decreased with depth. Δ4-Stenones were found in greater abundance than their saturated counterparts. Cholest-4-en-3-one was the major steroid ketone detected in all the traps. A five-fold increase with depth in the cholest-4-en-3-one to cholesterol ratio is most likely due to microbial oxidation of sterols to steroid ketones, or higher Δ4-stenone inputs relative to sterols from organisms.

  19. Anomalous opening of the Equatorial Atlantic due to an equatorial mantle thermal minimum

    NASA Astrophysics Data System (ADS)

    Bonatti, Enrico

    1996-09-01

    The geology of the Equatorial Atlantic is dominated by a broad east-west megashear belt where a cluster of large fracture zones offsets anomalously deep segments of the Mid-Atlantic Ridge (MAR). The origin and evolution of this megashear region may lie ultimately in an equatorial mantle thermal minimum. The notion of a mantle thermal minimum in the Equatorial Atlantic is supported by an equatorial minimum of zero-age topography, a maximum in mantle shear waves seismic velocity and a minimum in the degree of melting, indicated by the chemistry of MAR basalts and peridotites. This thermal minimum has probably been a stable feature since before the Cretaceous separation of Africa from South America; it caused a pre-opening equatorial continental lithosphere thicker and colder than normal. The Cretaceous Benue Trough in western Africa and the Amazon depression in South America are interpreted as morphostructural depressions created or rejuvenated by strike-slip, transpressional and transtensional tectonics ducing extension of the cold/thick equatorial lithosphere. The oceanic rift propagating northward from the South Atlantic impinged against the equatorial thicker, colder and, therefore, stronger than normal continental, lithosphere that consequently acted as a 'locked zone'. This, and a low magmatic budget due to the cold upper mantle, caused a lower than normal rate of propagation of the oceanic rift into the equatorial belt, with diffuse deformation during mostly amagmatic extension. The thick/cold lithosphere prevented major Cretaceous igneous activity from the St. Helena plume. Eventually initial 'weak' isolated nuclei oceanic lithosphere were emplaced, separated by E-W continent/continent transforms. Opening occurred largely by strike-slip motion along these initial transforms. The consequences were that the Equatorial Atlantic opened prevalently along an E-W direction, in contrast to the N-S opening of the North and South Atlantic, and that sheared continental

  20. Phanerozoic geological evolution of the Equatorial Atlantic domain

    NASA Astrophysics Data System (ADS)

    Basile, Christophe; Mascle, Jean; Guiraud, René

    2005-10-01

    The Phanerozoic geological evolution of the Equatorial Atlantic domain has been controlled since the end of Early Cretaceous by the Romanche and Saint Paul transform faults. These faults did not follow the PanAfrican shear zones, but were surimposed on Palæozoic basins. From Neocomian to Barremian, the Central Atlantic rift propagated southward in Cassiporé and Marajó basins, and the South Atlantic rift propagated northward in Potiguar and Benue basins. During Aptian times, the Equatorial Atlantic transform domain appeared as a transfer zone between the northward propagating tip of South Atlantic and the Central Atlantic. Between the transform faults, oceanic accretion started during Late Aptian in small divergent segments, from south to north: Benin-Mundaú, deep Ivorian basin-Barreirinhas, Liberia-Cassiporé. From Late Aptian to Late Albian, the Togo-Ghana-Ceará basins appeared along the Romanche transform fault, and Côte d'Ivoire-Parà-Maranhão basins along Saint Paul transform fault. They were rapidly subsiding in intra-continental settings. During Late Cretaceous, these basins became active transform continental margins, and passive margins since Santonian times. In the same time, the continental edge uplifted leading either to important erosion on the shelf or to marginal ridges parallel to the transform faults in deeper settings.

  1. The Cretaceous Thermal Maximum and Oceanic Anoxic Event 2 in the Tropics: Sea- Surface Temperature and Stable Organic Carbon Isotopic Records from the Equatorial Atlantic

    NASA Astrophysics Data System (ADS)

    Forster, A.; Schouten, S.; Baas, M.; Moriya, K.; Wilson, P. A.; Sinninghe Damsté, J. S.

    2006-12-01

    Oceanic Anoxic Event 2 (OAE-2) occurring during the Cenomanian/Turonian transition, is evident from a global positive stable carbon isotopic excursion and presumably represents the most extreme carbon cycle perturbation of the last 100 Myr. However, the impact of this major perturbation on and interaction with global climate remains unclear. OAE-2 occurred in the mid-Cretaceous, a time in Earth history characterized by extreme global warmth culminating in the so-called Cretaceous thermal maximum. Thus, records of paleo-sea surface temperatures (SSTs) from the mid-Cretaceous oceans are particularly important for understanding greenhouse climate conditions. We will present new high-resolution SST-records based on an organic proxy, the TetraEther indeX of 86 carbon atoms (TEX86), and δ18O of excellently preserved, "glassy" planktic foraminifera, combined with stable organic carbon isotopes generated from marine black shales located offshore Suriname/French Guiana (ODP Site 1260) and Senegal (DSDP Site 367). At Site 1260 a good match between conservative SST estimates from TEX86 and δ18O is observed. Late Cenomanian SSTs in the equatorial Atlantic Ocean (~33°C) were substantially warmer than today (~27-29°C) and the onset of OAE-2 coincided with a rapid shift to an even warmer (~35-36°C) regime. Within the early stages of OAE-2 a marked (~4°C) cooling is observed. However, well before the termination of OAE-2, the warm regime was re-established and persisted into the Turonian. Our findings corroborate the view that the C/T-transition represents the onset of peak Cretaceous warmth, that mid-Cretaceous warmth can be attributed to high levels of atmospheric CO2 and that major OAEs were capable of triggering global cooling through the negative feedback effect of organic carbon burial-led CO2-sequestration. However, the factors that gave rise to the observed shift to a warmer climate regime at the onset of OAE-2 were sufficiently powerful that they were only briefly

  2. North-south compression, active uplift, and abyssal mantle exhumation of the Saint Peter and Saint Paul Rock, Equatorial Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Motoki, A.; Sichel, S. E.; Campos, T. F.; Motoki, K. F.; Szatmari, P.; Poseidon-Colmeia

    2013-05-01

    This article presents near N-S compression, active uplift tectonism, and the consequent abyssal mantle exhumation of the Saint Peter and Saint Paul Rock, Equatorial Atlantic Ocean. The mantle peridotite ridge is about 80 km long, 25 km wide, 3800 m high, and of near E-W direction. The ridge flanks are extremely steep with sub-vertical scarps of about 2000 m of relative height. The Flandrian wave-cut and the 14C datings for the carbonaceous algae of the Saint Peter and Saint Paul Rock indicate active uplift of 1.5 mm/year. The tectonic factures shows conjugated system of N-S compression tending slightly to NW-ES. Close to the peridotite ridge, the earthquakes with near N-S compression focal mechanism take place. The southern half of the peridotite ridge is constituted by undeformed peridotite. The existence of corrugation morphology indicates that the mantle rocks are originated from old megamullion. On the other hand, the northern half is composed of strongly deformed mylonitic peridotite suggesting that the ultramafic rocks are possibly originated from sub-crustal abyssal mantle of old transform fault. The mylonite structure is intensely perturbed indicating the tectonic events which disturbed the original parallel structure. The Saint Paul transform fault zone is characterized by E-W trend right lateral movement and the near N-S compression is unlikely. Therefore, an unusual local geotectonic process is expected. This tectonism was originated from the plate boundary jump at about 8 Ma, caused by the emergence of a new ridge segment, and the new transform fault is oblique to the relative plate movement. This angular discrepancy causes the compression perpendicular to the oblique transform fault, of near N-S direction, which squeeze out the sub-crustal abyssal mantle up to sea level. Therefore, the peridotite Ridge is considered to be a pressure ridge of the strike-slip movement of the Saint Paul transform fault.

  3. Tropical warming and intermittent cooling during the Cenomanian/Turonian oceanic anoxic event 2: Sea surface temperature records from the equatorial Atlantic

    NASA Astrophysics Data System (ADS)

    Forster, Astrid; Schouten, Stefan; Moriya, Kazuyoshi; Wilson, Paul A.; Sinninghe Damsté, Jaap S.

    2007-03-01

    Oceanic anoxic event 2 (OAE-2) occurring during the Cenomanian/Turonian (C/T) transition is evident from a globally recognized positive stable carbon isotopic excursion and is thought to represent one of the most extreme carbon cycle perturbations of the last 100 Myr. However, the impact of this major perturbation on and interaction with global climate remains unclear. Here we report new high-resolution records of sea surface temperature (SST) based on TEX86 and δ18O of excellently preserved planktic foraminifera and stable organic carbon isotopes across the C/T transition from black shales located offshore Suriname/French Guiana (Demerara Rise, Ocean Drilling Program Leg 207 Site 1260) and offshore Senegal (Cape Verde Basin, Deep Sea Drilling Project Leg 41 Site 367). At Site 1260, where both SST proxy records can be determined, a good match between conservative SST estimates from TEX86 and δ18O is observed. We find that late Cenomanian SSTs in the equatorial Atlantic Ocean (≥33°C) were substantially warmer than today (˜27°-29°C) and that the onset of OAE-2 coincided with a rapid shift to an even warmer (˜35°-36°C) regime. Within the early stages of the OAE a marked (˜4°C) cooling to temperatures lower than pre-OAE conditions is observed. However, well before the termination of OAE-2 the warm regime was reestablished and persisted into the Turonian. Our findings corroborate the view that the C/T transition represents the onset of the interval of peak Cretaceous warmth. More importantly, they are consistent with the hypotheses that mid-Cretaceous warmth can be attributed to high levels of atmospheric carbon dioxide (CO2) and that major OAEs were capable of triggering global cooling through the negative feedback effect of organic carbon-burial-led CO2 sequestration. Evidently, however, the factors that gave rise to the observed shift to a warmer climate regime at the onset of OAE-2 were sufficiently powerful that they were only briefly counterbalanced

  4. Pelagic microplastics around an archipelago of the Equatorial Atlantic.

    PubMed

    Ivar do Sul, Juliana A; Costa, Monica F; Barletta, Mário; Cysneiros, Francisco José A

    2013-10-15

    Plastic marine debris is presently widely recognised as an important environmental pollutant. Such debris is reported in every habitat of the oceans, from urban tourist beaches to remote islands and from the ocean surface to submarine canyons, and is found buried and deposited on sandy and cobble beaches. Plastic marine debris varies from micrometres to several metres in length and is potentially ingested by animals of every level of the marine food web. Here, we show that synthetic polymers are present in subsurface plankton samples around Saint Peter and Saint Paul Archipelago in the Equatorial Atlantic Ocean. To explain the distribution of microplastics around the Archipelago, we proposed a generalised linear model (GLM) that suggests the existence of an outward gradient of mean plastic-particle densities. Plastic items can be autochthonous or transported over large oceanic distances. One probable source is the small but persistent fishing fleet using the area.

  5. Detailed Phosphorus Geochemistry of Sediments from the Equatorial Proto-Atlantic at Demerara Rise During Oceanic Anoxic Event 2

    NASA Astrophysics Data System (ADS)

    Smith, M. E.; Latimer, J.; Pugh, E.

    2011-12-01

    Oceanic anoxic events (OAE) are associated with increased organic matter burial and possibly major changes in marine nutrient cycling. Phosphorus (P) limits biological productivity on geologic timescales, thus detailed P geochemistry may provide insight into the role of nutrients on the formation of these organic-rich deposits. P geochemical records that encompass the complete OAE 2 interval across the Cenomanian-Turonian boundary (CTB, ~94 Ma) are rare, and detailed P geochemical records are usually limited to relatively shallow settings. In this study, a sequential extraction (SEDEX) technique is employed to evaluate the sedimentary distribution of P (oxide-associated, authigenic, detrital and organic) in sediments mainly consisting of laminated black shales spanning the CTB/OAE2 interval at a sample resolution of ~2-5 cm collected from Demerara Rise during ODP Leg 207. Intermediate (Site 1260, 2549 m) and deep-sea (Site 1258, 3292 m) water depths will be compared to assess variations in P distribution across the CTB, with paleo-water depths of ~500 to 1000 m respectively. Diagenetic and redox conditions result in alterations of the sedimentary distribution of P in ancient sediments; most notably the effect of "sink-switching" of organic P to authigenic and/or oxide-associated phases. Here we evaluate the impacts of diagenetic remobilization of P through the critical OAE 2 interval. Sequential extraction enables an examination of the dominant pathways of P removal from the ocean thus providing insight into marine P mass balance. Initial results reveal little or undetectable concentrations of oxide-associated and organic P. Authigenic and detrital phases dominate the extractable P. Under anoxic conditions Fe-oxides would no longer be a major sedimentary sink and would likely lead to losses of oxide-associated P from the sediments. Low concentrations of organic P are likely due to diagenetic alteration to authigenic carbonate fluorapatite (CFA) and oxide

  6. Coupled marine productivity and salinity and West African monsoon variability over the last 30,000 years in the eastern equatorial Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Marret, F.; Kim, S.-Y.; Scourse, J.; Kennedy, H.

    2009-04-01

    around 20 cal ka BP, and the second from 15.2 to 13.2 cal ka BP, during the deglaciation period, when strengthening of the monsoon occurred in a context of open vegetation, allowing an increased erosion of soil. Evidence of decrease salinity due to strengthening of the monsoon dynamics is also observed from the Sanaga core, with the increased abundance of a marine taxon linked to low saline context from 12.5 cal ka BP onwards (2). The study of these integrated records of marine and terrestrial proxies illustrates the complexity of interactions between land-ocean and atmospheric systems and emphasizes the need for high-resolution records to fully understand the coupled equatorial climate system. References 1- Marret, F., Scourse, J., Kennedy, H. Ufkes, E., and Jansen, J.H.F., 2008. Marine production in the Congo-influenced SE Atlantic over the past 30,000 years: A novel dinoflagellate-cyst based transfer function approach. Marine Micropaleontology 68, 198-222. 2- Kim, S.Y., 2007, Dinoflagellate cyst and pollen stratigraphy of Niger and Ogouée fan sediments covering the last glacial cycle. PhD thesis, Bangor University.

  7. Interannual Variability of Boreal Summer Rainfall in the Equatorial Atlantic

    NASA Technical Reports Server (NTRS)

    Gu, Guojun; Adler, Robert F.

    2007-01-01

    Tropical Atlantic rainfall patterns and variation during boreal summer [June-July-August (JJA)] are quantified by means of a 28-year (1979-2006) monthly precipitation dataset from the Global Precipitation Climatology Project (GPCP). Rainfall variability during boreal spring [March-April-May (MAM)] is also examined for comparison in that the most intense interannual variability is usually observed during this season. Comparable variabilities in the Intertropical Convergence Zone (ITCZ) strength and the basin-mean rainfall are found during both seasons. Interannual variations in the ITCZ's latitudinal location during JJA however are generally negligible, in contrasting to intense year-to-year fluctuations during MAM. Sea surface temperature (SST) oscillations along the equatorial region (usually called the Atlantic Nino events) and in the tropical north Atlantic (TNA) are shown to be the two major local factors modulating the tropical Atlantic climate during both seasons. During MAM, both SST modes tend to contribute to the formation of an evident interhemispheric SST gradient, thus inducing anomalous shifting of the ITCZ and then forcing a dipolar structure of rainfall anomalies across the equator primarily in the western basin. During JJA the impacts however are primarily on the ITCZ strength likely due to negligible changes in the ITCZ latitudinal location. The Atlantic Nino reaches its peak in JJA, while much weaker SST anomalies appear north of the equator in JJA than in MAM, showing decaying of the interhemispheric SST mode. SST anomalies in the tropical central-eastern Pacific (the El Nino events) have a strong impact on tropical Atlantic including both the tropical north Atlantic and the equatorial-southern Atlantic. However, anomalous warming in the tropical north Atlantic following positive SST anomalies in the tropical Pacific disappears during JJA because of seasonal changes in the large-scale circulation cutting off the ENSO influence passing through the

  8. Role of interannual Kelvin wave propagations in the equatorial Atlantic on the Angola Benguela Current system

    NASA Astrophysics Data System (ADS)

    Imbol Koungue, Rodrigue Anicet; Illig, Serena; Rouault, Mathieu

    2017-06-01

    The link between equatorial Atlantic Ocean variability and the coastal region of Angola-Namibia is investigated at interannual time scales from 1998 to 2012. An index of equatorial Kelvin wave activity is defined based on Prediction and Research Moored Array in the Tropical Atlantic (PIRATA). Along the equator, results show a significant correlation between interannual PIRATA monthly dynamic height anomalies, altimetric monthly Sea Surface Height Anomalies (SSHA), and SSHA calculated with an Ocean Linear Model. This allows us to interpret PIRATA records in terms of equatorial Kelvin waves. Estimated phase speed of eastward propagations from PIRATA equatorial mooring remains in agreement with the linear theory, emphasizing the dominance of the second baroclinic mode. Systematic analysis of all strong interannual equatorial SSHA shows that they precede by 1-2 months extreme interannual Sea Surface Temperature Anomalies along the African coast, which confirms the hypothesis that major warm and cold events in the Angola-Benguela current system are remotely forced by ocean atmosphere interactions in the equatorial Atlantic. Equatorial wave dynamics is at the origin of their developments. Wind anomalies in the Western Equatorial Atlantic force equatorial downwelling and upwelling Kelvin waves that propagate eastward along the equator and then poleward along the African coast triggering extreme warm and cold events, respectively. A proxy index based on linear ocean dynamics appears to be significantly more correlated with coastal variability than an index based on wind variability. Results show a seasonal phasing, with significantly higher correlations between our equatorial index and coastal SSTA in October-April season.

  9. Fertilizing the Amazon and equatorial Atlantic with West African dust

    NASA Astrophysics Data System (ADS)

    Bristow, Charlie S.; Hudson-Edwards, Karen A.; Chappell, Adrian

    2010-07-01

    Atmospheric mineral dust plays a vital role in Earth's climate and biogeochemical cycles. The Bodélé Depression in Chad has been identified as the single biggest source of atmospheric mineral dust on Earth. Dust eroded from the Bodélé is blown across the Atlantic Ocean towards South America. The mineral dust contains micronutrients such as Fe and P that have the potential to act as a fertilizer, increasing primary productivity in the Amazon rain forest as well as the equatorial Atlantic Ocean, and thus leading to N2 fixation and CO2 drawdown. We present the results of chemical analysis of 28 dust samples collected from the source area, which indicate that up to 6.5 Tg of Fe and 0.12 Tg of P are exported from the Bodélé Depression every year. This suggests that the Bodélé may be a more significant micronutrient supplier than previously proposed.

  10. Long waves in the equatorial Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Philander, George; Halpern, David; Hansen, Donald; Legeckis, Richard; Miller, Laury; Watts, Randolph; Wimbush, Mark; Paul, Carl; Watts, Randolph; Weisberg, Robert

    Westward traveling waves, with a period of 3 weeks and a wavelength of ˜1000 km, are observed intermittently in the central and eastern equatorial Pacific Ocean (see cover). The waves were first detected in 1975 in satellite measurements of the sea surface temperature [Legeckis, 1977]. Since then, additional measurements (under the auspices of the NOAA program Equatorial Pacific Ocean Climate Studies (EPOCS)) with a variety of instruments—drifting buoys, current meters and temperature sensors on moorings, and inverted echo sounders—have provided considerable information about these waves and have confirmed the hypothesis that they are caused by instabilities associated primarily with the latitudinal shear of the surface currents near the equator [Philander, 1978a; Cox, 1980].

  11. Models of the Equatorial Ocean Circulation.

    DTIC Science & Technology

    1980-01-01

    doctoral committee for their encouragement and advice in the development of this work. I am especially indebted to Dr. Julian P. McCreary of Nova University...large scale wind fluctuations thousands of kilometers to the west in the Central Pacific ( McCreary , 1977). A better understanding of such events could...all equatorial oceans can be found in Knauss (1963); Philander (1973b); Leetmaa, McCreary and Moore (1980); Tsuchiya (1975); Cochrane et al. (1979) and

  12. 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.

  13. Phase locking of equatorial Atlantic variability through the seasonal migration of the ITCZ

    NASA Astrophysics Data System (ADS)

    Richter, Ingo; Xie, Shang-Ping; Morioka, Yushi; Doi, Takeshi; Taguchi, Bunmei; Behera, Swadhin

    2017-06-01

    The equatorial Atlantic is marked by significant interannual variability in sea-surface temperature (SST) that is phase-locked to late boreal spring and early summer. The role of the atmosphere in this phase locking is examined using observations, reanalysis data, and model output. The results show that equatorial zonal surface wind anomalies, which are a main driver of warm and cold events, typically start decreasing in June, despite SST and sea-level pressure gradient anomalies being at their peak during this month. This behavior is explained by the seasonal northward migration of the intertropical convergence zone (ITCZ) in early summer. The north-equatorial position of the Atlantic ITCZ contributes to the decay of wind anomalies in three ways: (1) horizontal advection associated with the cross-equatorial winds transports air masses of comparatively low zonal momentum anomalies from the southeast toward the equator. (2) The absence of deep convection leads to changes in vertical momentum transport that reduce the equatorial wind anomalies at the surface, while anomalies aloft remain relatively strong. (3) The cross-equatorial flow is associated with increased total wind speed, which increases surface drag and deposit of momentum into the ocean. Previous studies have shown that convection enhances the surface wind response to SST anomalies. The present study indicates that convection also amplifies the surface zonal wind response to sea-level pressure gradients in the western equatorial Atlantic, where SST anomalies are small. This introduces a new element into coupled air-sea interaction of the tropical Atlantic.

  14. Mean meridional currents in the central and eastern equatorial Atlantic

    NASA Astrophysics Data System (ADS)

    Perez, Renellys C.; Hormann, Verena; Lumpkin, Rick; Brandt, Peter; Johns, William E.; Hernandez, Fabrice; Schmid, Claudia; Bourlès, Bernard

    2014-12-01

    Ship-based acoustic Doppler current profiler (ADCP) velocity measurements collected by several major field programs in the tropical Atlantic are averaged and combined with estimates of the mean near-surface velocity derived from drifters and Argo float surface drifts (ADCP+D) to describe the mean cross-equatorial and vertical structure of the meridional currents along 23°W and 10°W. Data from moored ADCPs and fixed-depth current meters, a satellite-derived velocity product, and a global ocean reanalysis were additionally used to evaluate the mean ADCP+D meridional velocity. The dominant circulation features in the long-term mean ADCP+D meridional velocity in the upper 100 m are the tropical cells (TCs) located approximately between 5°S and 5°N, with near-surface poleward flow and subsurface equatorward flow that is stronger and shallower in the northern cell compared to the southern cell. The thickness of the surface limb of the TCs decreases and the northern cell is found to shift further south of the equator from the central to eastern tropical Atlantic. Analysis of two-season means estimated from the ship-based ADCP, near-surface drift, and moored velocity data, as well as the simulated fields, indicates that the maximum poleward velocity in the surface limb of the TCs intensifies during December-May along 23°W largely due to seasonal compensation between the geostrophic and ageostrophic (or wind-driven) components of the meridional velocity, whereas the maximum equatorward flow in the subsurface limb of the northern cell intensifies during June-November along both 23°W and 10°W due to the seasonality of the geostrophic meridional velocity.

  15. Why are rings regularly shed in the western equatorial Atlantic but not in the western Pacific?

    NASA Astrophysics Data System (ADS)

    Nof, Doron

    The western equatorial Atlantic is characterized by the formation and shedding of 3-4 large anticyclonic rings per year. These rings originate from the North Brazil Current which, in response to the vanishing wind stress curl (over the ocean interior), retroflects and turns eastward at around 4°N. After their formation and shedding the rings propagate toward the northwest along the South American coast carrying an annual average of about 4Sv. As such, the rings constitute an important part of the meridional heat flux in the Atlantic. The same cannot be said, however, of the western equatorial Pacific. Here, the situation is entirely different even though the South Equatorial Current retroflects at roughly the same latitude as its Atlantic counterpart, the North Brazil Current. Although the South Equatorial Current retroflection is flanked by two quasi-permanent eddies (the so-called Halmahera and the Mindanao eddies), these eddies are an integral part of the current itself and are not shed. Consequently, they are not associated with any meridional heat flux. An important question is, then, why the two oceans behave in such a fundamentally different way even though the source of the rings, the retroflected currents, are very similar in the two oceans. To answer this question, the two oceans are compared using recently developed analytical and numerical models for the western equatorial oceans. It is first pointed out that, according to recent developments in the modelling of the western equatorial Atlantic, the North Brazil Current retroflection rings are formed, shed and drift to the west because, in the Atlantic, this is the only way by which the momentum flux of the approaching and retroflecting current can be balanced. In this scenario, the northwestward flow force exerted by the approaching and retroflecting North Brazil Current (analogous to the force created by a rocket) is balanced by the southwestward force exerted by the rings as they are formed

  16. Ocean atmosphere thermal decoupling in the eastern equatorial Indian ocean

    NASA Astrophysics Data System (ADS)

    Joseph, Sudheer; Ravichandran, M.; Kumar, B. Praveen; Jampana, Raju V.; Han, Weiqing

    2016-09-01

    Eastern equatorial Indian ocean (EEIO) is one of the most climatically sensitive regions in the global ocean, which plays a vital role in modulating Indian ocean dipole (IOD) and El Niño southern oscillation (ENSO). Here we present evidences for a paradoxical and perpetual lower co-variability between sea-surface temperature (SST) and air-temperature (Tair) indicating instantaneous thermal decoupling in the same region, where signals of the strongly coupled variability of SST anomalies and zonal winds associated with IOD originate at inter-annual time scale. The correlation minimum between anomalies of Tair and SST occurs in the eastern equatorial Indian ocean warm pool region (≈70°E-100°E, 5°S-5°N), associated with lower wind speeds and lower sensible heat fluxes. At sub-monthly and Madden-Julian oscillation time scales, correlation of both variables becomes very low. In above frequencies, precipitation positively contributes to the low correlation by dropping Tair considerably while leaving SST without any substantial instant impact. Precipitation is led by positive build up of SST and post-facto drop in it. The strong semi-annual response of SST to mixed layer variability and equatorial waves, with the absence of the same in the Tair, contributes further to the weak correlation at the sub-annual scale. The limited correlation found in the EEIO is mainly related to the annual warming of the region and ENSO which is hard to segregate from the impacts of IOD.

  17. Ocean atmosphere thermal decoupling in the eastern equatorial Indian ocean

    NASA Astrophysics Data System (ADS)

    Joseph, Sudheer; Ravichandran, M.; Kumar, B. Praveen; Jampana, Raju V.; Han, Weiqing

    2017-07-01

    Eastern equatorial Indian ocean (EEIO) is one of the most climatically sensitive regions in the global ocean, which plays a vital role in modulating Indian ocean dipole (IOD) and El Niño southern oscillation (ENSO). Here we present evidences for a paradoxical and perpetual lower co-variability between sea-surface temperature (SST) and air-temperature (Tair) indicating instantaneous thermal decoupling in the same region, where signals of the strongly coupled variability of SST anomalies and zonal winds associated with IOD originate at inter-annual time scale. The correlation minimum between anomalies of Tair and SST occurs in the eastern equatorial Indian ocean warm pool region (≈70°E-100°E, 5°S-5°N), associated with lower wind speeds and lower sensible heat fluxes. At sub-monthly and Madden-Julian oscillation time scales, correlation of both variables becomes very low. In above frequencies, precipitation positively contributes to the low correlation by dropping Tair considerably while leaving SST without any substantial instant impact. Precipitation is led by positive build up of SST and post-facto drop in it. The strong semi-annual response of SST to mixed layer variability and equatorial waves, with the absence of the same in the Tair, contributes further to the weak correlation at the sub-annual scale. The limited correlation found in the EEIO is mainly related to the annual warming of the region and ENSO which is hard to segregate from the impacts of IOD.

  18. A Long, Consistent Surface Wind Dataset for Climate Change Analysis: Application over the Equatorial Atlantic

    NASA Astrophysics Data System (ADS)

    Tokinaga, H.; Xie, S.

    2010-12-01

    Surface wind change is a principal factor for spatial patterns of sea surface temperature (SST) warming through changes in surface evaporation, ocean vertical mixing and wind-driven ocean circulation. However, historical ship-based measurements of sea surface wind speed displays a spurious upward trend due to increases in anemometer height. To correct this bias, we construct the Wave and Anemometer-based Sea-surface Wind (WASWind) dataset for the last six decades from ICOADS ship reports, applying height correction for anemometer measured winds, rejecting spurious Beaufort winds, and using wind wave height to estimate wind speed. WASWind substantially reduces the upward trend in wind speed and its trend patterns are quite similar to satellite-measured surface wind changes for the recent two decades. Surface wind changes in WASWind are consistent with historical sea level pressure observations over the global oceans, illustrating its utility for climate change analysis. As an example, WASWind captures relaxation of the equatorial trade winds coupled with a weakening of the equatorial Atlantic cold tongue over the last six decades. The surface wind changes are also consistent with those in atmospheric convection and subsurface temperature in this region, indicating that thermocline feedback plays a key role in recent climate change over the equatorial Atlantic.

  19. Formerly emerging crustal blocks in the equatorial Atlantic

    NASA Astrophysics Data System (ADS)

    Bonatti, Enrico; Chermak, Andy

    1981-02-01

    Anomalous crustal topographic highs, exceeding the level predicted by the thermal contraction model by up to 2-3 km, are observed along the Romanche Transform Zone in the equatorial Atlantic. Previous studies of shallow-water reef limestones recovered from one of the shallowest sites on these crustal highs indicated that this site was at or above sea level 5 million years ago and subsided since at an average rate one order of magnitude faster than the subsidence estimated by thermal contraction of the crust. Seismic reflection profiles obtained across the Romanche Transform Zone suggest that the anomalous highs are capped by reef limestones not only where limestones were actually sampled, but also at other locations. These findings support the idea that long segments of crust reached close to sea level in the past along the Romanche Transform Zone. The vertical crustal motions are probably caused by tectonism typical of long-offset transforms. Inasmuch as the Romanche has been a ridge—ridge transform since the earliest stages of the opening of the equatorial Atlantic, it is likely that intense vertical tectonic motions occurred along it throughout the evolution of the Atlantic. Support for this hypothesis is provided by the recovery during DSDP Leg 4 of shallow water reef limestone of the Eocene Age from the summit of the North Brazilian Ridge along the western extension of the Romanche Fracture Zone. The presence of shallow or emergent crust across the equatorial zone during the early stages of opening had probably important consequences upon the water circulation between the North and the South Atlantic, and may even have provided "land bridges" for faunal migrations between Africa and South America in early Cenozoic times after the two continents had already separated.

  20. Annual, orbital, and enigmatic variations in tropical oceanography recorded by the Equatorial Atlantic amplifier

    NASA Technical Reports Server (NTRS)

    Mcintyre, Andrew

    1992-01-01

    Equatorial Atlantic surface waters respond directly to changes in zonal and meridional lower tropospheric winds forced by annual insolation. This mechanism has its maximum effect along the equatorial wave guide centered on 10 deg W. The result is to amplify even subtle tropical climate changes such that they are recorded by marked amplitude changes in the proxy signals. Model realizations, NCAR AGCM and OGCM for 0 Ka and 126 Ka (January and July), and paleoceanographic proxy data show that these winds are also forced by insolation changes at the orbital periods of precession and obliquity. Perhelion in boreal summer produces a strengthened monsoon, e.g., increase meridional and decrease zonal wind stress. This reduces oceanic Ekman divergence and thermocline/nutricline shallowing. The result, in the equatorial Atlantic, is reduced primary productivity and higher euphotic zone temperatures; vice versa for perihelion in boreal winter. Perihelion is controlled by precession. Thus, the dominant period in spectra from a stacked SST record (0-252 Ka BP) at the site of the equatorial Atlantic amplifier is 23 Ky (53 percent of the total variance). This precessional period is coherent (k = 0.920) and in phase with boreal summer insolation. Oscillations of shorter period are present in records from cores sited beneath the amplifier region. These occur between 12.5 and 74.5 Ka BP, when eccentricity modulation of precession is at a minimum. Within this time interval there are 21 cycles with mean periods of 3.0 plus or minus 0.5 Ky. Similar periods have been documented from high latitude regions, e.g., Greenland ice cores from Camp Century. The Camp Century signal in this same time interval contains 21 cycles. A subjective correlation was made between the Camp Century and the equatorial records; the signals were statistically similar, r = 0.722 and k = 0.960.

  1. Oceanic origin of southeast tropical Atlantic biases

    NASA Astrophysics Data System (ADS)

    Xu, Zhao; Li, Mingkui; Patricola, Christina M.; Chang, Ping

    2014-12-01

    Most coupled general circulation models suffer from a prominent warm sea surface temperature bias in the southeast tropical Atlantic Ocean off the coast of Africa. The origin of the bias is not understood and remains highly controversial. Previous studies suggest that the origin of the bias stems from systematic errors of atmospheric models in simulating surface heat flux and coastal wind, or poorly simulated coastal upwelling. In this study, we show, using different reanalysis and observational data sets combined with a set of eddy-resolving regional ocean model simulations, that systematic errors in ocean models also make a significant contribution to the bias problem. In particular (1) the strong warm bias at the Angola-Benguela front that is maintained by the local wind and the convergence of Angola and Benguela Currents is caused by an overshooting of the Angola Current in ocean models and (2) the alongshore warm bias to the south of the front is caused by ocean model deficiencies in simulating the sharp thermocline along the Angola coast, which is linked to biases in the equatorial thermocline, and the complex circulation system within the Benguela upwelling zone.

  2. Seasonal Cycle of Cross Equatorial Flow in the Central Equatorial Indian Ocean

    NASA Astrophysics Data System (ADS)

    McPhaden, Michael; Wang, Yi

    2017-04-01

    This study investigates the seasonal cycle of meridional currents in the upper layers of central equatorial Indian Ocean using acoustic Doppler current profiler (ADCP) data and other data sets along 80.5°E for the period 2004-13. The ADCP data set is the most comprehensive collection of direct velocity measurements in the central Indian Ocean to date, providing new insights into cross equatorial flow in this region. Mean meridional currents are characterized by subsurface divergence between 50-100 m depths with relatively weak convergence above, driven by the annual mean westward pressure gradient force and the surface westerly wind stress respectively. However, in response to a mean northward component of the surface wind stress, the maximum mean surface layer convergence is shifted off the equator to 0.75°N. Evidence is also presented for the existence of a shallow equatorial roll, consisting of a northward wind-driven surface drift overlaying a southward subsurface flow. Cross equatorial transports during boreal summer and winter indicate that a quasi-steady Sverdrup transport balance dominates the seasonal cycle of upper-layer meridional currents. In addition, semi-annually varying westerly monsoon transition winds force Ekman convergence in the surface layer and set up transient zonal pressure gradients that drive seasonally enhanced meridional geostrophic divergence in the thermocline. These results quantify expectations from ocean circulation theories for equatorial Indian Ocean meridional circulation patterns with a high degree of confidence given the length of the data records.

  3. /sup 14/C distribution in the Atlantic Ocean

    SciTech Connect

    Stuiver, M.

    1980-05-20

    The amount of /sup 14/C produced by nuclear bomb testing that entered the Atlantic Ocean by late 1972 was 1.71 x 10/sup -8/ ..mu..mol/cm/sup 2/ of ocean surface area for the west Atlantic (36/sup 0/S-45/sup 0/N) and 1.18 x 10/sup -8/ ..mu..mol/cm/sup 2/ for the east Atlantic (50/sup 0/S-28/sup 0/N) Geochemical Ocean Sections Study stations. There are strong latitudinal differences in the integrated amount of bomb /sup 14/C content in Atlantic waters. Bomb-produced /sup 14/C is mostly encountered near the center of the large mid-latitude gyres, whereas the equatorial region has a lower /sup 14/C inventory. The average ocean wide vertical distribution of bomb /sup 14/C in the Atlantic can be explained by a vertical eddy diffusion coefficient of 4.0 cm/sup 2//s in the surface mixed layer plus thermocline gyre reservoirs. The average /sup 14/C activity per unit area measured in the Atlantic yields an atmosphere-ocean CO/sub 2/ exchange rate of 23 mol/m/sup 2/ yr, which is equivalent with an atmospheric CO/sub 2/ residence time of 6.8 years.

  4. Water-mass evolution in the Cretaceous Western Interior Seaway of North America and equatorial Atlantic

    NASA Astrophysics Data System (ADS)

    Eldrett, James S.; Dodsworth, Paul; Bergman, Steven C.; Wright, Milly; Minisini, Daniel

    2017-07-01

    The Late Cretaceous Epoch was characterized by major global perturbations in the carbon cycle, the most prominent occurring near the Cenomanian-Turonian (CT) transition marked by Oceanic Anoxic Event 2 (OAE-2) at 94.9-93.7 Ma. The Cretaceous Western Interior Seaway (KWIS) was one of several epicontinental seas in which a complex water-mass evolution was recorded in widespread sedimentary successions. This contribution integrates new data on the main components of organic matter, geochemistry, and stable isotopes along a north-south transect from the KWIS to the equatorial western Atlantic and Southern Ocean. In particular, cored sedimentary rocks from the Eagle Ford Group of west Texas (˜ 90-98 Ma) demonstrate subtle temporal and spatial variations in palaeoenvironmental conditions and provide an important geographic constraint for interpreting water-mass evolution. High-latitude (boreal-austral), equatorial Atlantic Tethyan and locally sourced Western Interior Seaway water masses are distinguished by distinct palynological assemblages and geochemical signatures. The northward migration of an equatorial Atlantic Tethyan water mass into the KWIS occurred during the early-middle Cenomanian (98-95 Ma) followed by a major re-organization during the latest Cenomanian-Turonian (95-94 Ma) as a full connection with a northerly boreal water mass was established during peak transgression. This oceanographic change promoted de-stratification of the water column and improved oxygenation throughout the KWIS and as far south as the Demerara Rise off Suriname. In addition, the recorded decline in redox-sensitive trace metals during the onset of OAE-2 likely reflects a genuine oxygenation event related to open water-mass exchange and may have been complicated by variable contribution of organic matter from different sources (e.g. refractory/terrigenous material), requiring further investigation.

  5. Massively parallel implementation of a high order domain decomposition equatorial ocean model

    SciTech Connect

    Ma, H.; McCaffrey, J.W.; Piacsek, S.

    1999-06-01

    The present work is about the algorithms and parallel constructs of a spectral element equatorial ocean model. It shows that high order domain decomposition ocean models can be efficiently implemented on massively parallel architectures, such as the Connection Machine Model CM5. The optimized computational efficiency of the parallel spectral element ocean model comes not only from the exponential convergence of the numerical solution, but also from the work-intensive, medium-grained, geometry-based data parallelism. The data parallelism is created to efficiently implement the spectral element ocean model on the distributed-memory massively parallel computer, which minimizes communication among processing nodes. Computational complexity analysis is given for the parallel algorithm of the spectral element ocean model, and the model's parallel performance on the CM5 is evaluated. Lastly, results from a simulation of wind-driven circulation in low-latitude Atlantic Ocean are described.

  6. MASSIVELY PARALLEL IMPLEMENTATION OF A HIGH ORDER DOMAIN DECOMPOSITION EQUATORIAL OCEAN MODEL

    SciTech Connect

    MA,H.; MCCAFFREY,J.W.; PIACSEK,S.

    1998-07-15

    The present work is about the algorithms and parallel constructs of a spectral element equatorial ocean model. It shows that high order domain decomposition ocean models can be efficiently implemented on massively parallel architectures, such as the Connection Machine Model CM5. The optimized computational efficiency of the parallel spectral element ocean model comes not only from the exponential convergence of the numerical solution, but also from the work-intensive, medium-grained, geometry-based data parallelism. The data parallelism is created to efficiently implement the spectral element ocean model on the distributed-memory massively parallel computer, which minimizes communication among processing nodes. Computational complexity analysis is given for the parallel algorithm of the spectral element ocean model, and the model's parallel performance on the CM5 is evaluated. Lastly, results from a simulation of wind-driven circulation in low-latitude Atlantic ocean are described.

  7. Sedimentary cover deformations in the equatorial Atlantic and their comparison with geophysical fields

    NASA Astrophysics Data System (ADS)

    Sokolov, S. Yu.

    2017-01-01

    The deformations of the sedimentary cover at near-latitudinal geotraverses west and east of the Mid-Atlantic Ridge in the equatorial part of ocean are compared with potential fields and variations of the V p/ V s attribute at a depth of 470 km. The features of sedimentary cover deformations in abyssal basins are formulated, as well as their differences from the undisturbed bedding of sediments. The elements of chain of phenomena with common spatial manifestations and cause-and-effect relationships have been established, including heterogeneous horizontal movements, which make up macrojointing above "cold" mantle blocks at a depth of 470 km; serpentinization of upper-mantle rocks; the formation of superposed magnetic anomalies; the release of the fluids, which acoustically bleach out the sedimentary sequence in seismic imaging; and decompaction of rocks leading to vertical motions and forced folding. The origin of the Atlantic marginal dislocation zone is explained. The coincidence of the deformation boundary in the equatorial Atlantic with the zero contour line of the V p/ V s attribute is revealed. This coincidence is an indicator of the rheological state of the upper mantle.

  8. Changes in North Atlantic nitrogen fixation controlled by ocean circulation.

    PubMed

    Straub, Marietta; Sigman, Daniel M; Ren, Haojia; Martínez-García, Alfredo; Meckler, A Nele; Hain, Mathis P; Haug, Gerald H

    2013-09-12

    In the ocean, the chemical forms of nitrogen that are readily available for biological use (known collectively as 'fixed' nitrogen) fuel the global phytoplankton productivity that exports carbon to the deep ocean. Accordingly, variation in the oceanic fixed nitrogen reservoir has been proposed as a cause of glacial-interglacial changes in atmospheric carbon dioxide concentration. Marine nitrogen fixation, which produces most of the ocean's fixed nitrogen, is thought to be affected by multiple factors, including ocean temperature and the availability of iron and phosphorus. Here we reconstruct changes in North Atlantic nitrogen fixation over the past 160,000 years from the shell-bound nitrogen isotope ratio ((15)N/(14)N) of planktonic foraminifera in Caribbean Sea sediments. The observed changes cannot be explained by reconstructed changes in temperature, the supply of (iron-bearing) dust or water column denitrification. We identify a strong, roughly 23,000-year cycle in nitrogen fixation and suggest that it is a response to orbitally driven changes in equatorial Atlantic upwelling, which imports 'excess' phosphorus (phosphorus in stoichiometric excess of fixed nitrogen) into the tropical North Atlantic surface. In addition, we find that nitrogen fixation was reduced during glacial stages 6 and 4, when North Atlantic Deep Water had shoaled to become glacial North Atlantic intermediate water, which isolated the Atlantic thermocline from excess phosphorus-rich mid-depth waters that today enter from the Southern Ocean. Although modern studies have yielded diverse views of the controls on nitrogen fixation, our palaeobiogeochemical data suggest that excess phosphorus is the master variable in the North Atlantic Ocean and indicate that the variations in its supply over the most recent glacial cycle were dominated by the response of regional ocean circulation to the orbital cycles.

  9. A Linear Stratified Ocean Model of the Equatorial Undercurrent

    NASA Astrophysics Data System (ADS)

    McCreary, J. P.

    1981-01-01

    A linear stratified ocean model is used to study the wind-driven response of the equatorial ocean. The model is an extension of the Lighthill (1969) model that allows the diffusion of heat and momentum into the deeper ocean, and so can develop non-trivial steady solutions. To retain the ability to expand solutions into sums of vertical normal modes, mixing coefficients must be inversely proportional to the square of the background Vaisala frequency. The model is also similar to the earlier homogeneous ocean model of Stommel (1960). He extended Ekman dynamics to the equator by allowing his model to generate a barotropic pressure field. The present model differs in that the presence of stratification allows the generation of a baroclinic pressure field as well. The most important result of this paper is that linear theory can produce a realistic equatorial current structure. The model Undercurrent has a reasonable width and depth scale. There is westward flow both above and below the Undercurrent. The meridional circulation conforms to the 'classical' picture suggested by Cromwell (1953). Unlike the Stommel solution, the response here is less sensitive to variations of parameters. Ocean boundaries are not necessary for the existence of the Undercurrent but are necessary for the existence of the deeper Equatorial Intermediate Current. The radiation of equatorially trapped Rossby and Kelvin waves is essential to the development of a realistic Undercurrent. Because the system supports the existence of these waves, low-order vertical modes can very nearly adjust to Sverdrup balance (defined below), which in a bounded ocean and for winds without curl is a state of rest. As a result, higher-order vertical modes are much more visible in the total solution. This property accounts for the surface trapping and narrow width scale of the equatorial currents. The high-order modes tend to be in Yoshida balance (defined below) and generate the characteristic meridional circulation

  10. 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.

  11. 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.

  12. 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.

  13. Sediment Provenance in the Equatorial Atlantic and its Implications on Paleocirculation

    NASA Astrophysics Data System (ADS)

    Pahler, S. H.; Franzese, A. M.; Hemming, S. R.

    2005-12-01

    Ocean circulation in the Equatorial Atlantic is composed of a diverse range of currents from the surface level equatorial currents and countercurrents to the North Atlantic Deep Water (NADW). Sediments deposited in this region are derived from Africa and South America by a combination of aeolian and fluvial pathways and then transported by ocean currents. Fifteen cores from the Equatorial Atlantic (10°N to 10°S, 0° to 45°W) were used to determine sediment provenance during the Holocene and Last Glacial Maximum (LGM), and specifically to test whether sediment was transported by surface or deep water currents. The radiogenic isotopic composition of any rock depends on its age, initial composition and its geologic history. The strontium isotopic composition of the terrigenous portion of marine sediments can often be used to identify the source rock(s) from which they weathered. By incorporating this new sediment core data from both Holocene and LGM depths with previous research designating the 87Sr/86Sr ratios for source areas in Africa and South America we were able to connect possible source areas with core locations. In general, the 87Sr/86Sr ratios from the Holocene are higher than those from the LGM, indicating a greater contribution from geologically older sediment sources during the Holocene. Primary sediment transport from African sources is best explained by wind transport, while sediment derived from South American sources is most easily explained by river input. The geographic pattern of 87Sr/86Sr ratios appears to be correlated to deep ocean circulation, specifically the NADW which flows southward along the western side of the Atlantic near South America and then cuts east along the Romanche Fracture Zone (RFZ, ~0°) before continuing south once again in the eastern basin near Africa. Based on our results, there is no observable difference in transport mechanisms between the Holocene and LGM; however, the difference in ratios between the two time

  14. The seismicity of the equatorial Mid-Atlantic Ridge and its long-offset transforms

    NASA Astrophysics Data System (ADS)

    Smith, D. K.; Dziak, R. P.; Palmiotto, C.; Parnell-Turner, R. E.; Zheleznov, A.

    2012-12-01

    An array of eight hydrophones is monitoring seismicity of the equatorial Atlantic between 20N and 10S. The array is obtaining a two-year, continuous record of seismicity, which will provide an important new view of the spatial and temporal patterns of seismicity at the slow-spreading equatorial Mid-Atlantic Ridge (MAR) and its long-offset transforms. The hydroacoustically-recorded seismicity, which will be in hand in 2014, can be used to address several key questions concerning the modes of spreading along the strongly offset equatorial MAR, the short-term earthquake predictability on some of the longest transform faults in the oceans, and the dynamics of the NA-SA-AF triple junction whose exact location is not known. In addition, seismic patterns of the entire South Atlantic will be obtained (at reduced location accuracy), and will aid in understanding the dynamics of the southern MAR, Walvis Ridge, Rio Grande Rise, and other prominent seafloor features. The hydroacoustic data will also allow characterization of cetacean populations in the region as well as an assessment of the ambient noise levels due to shipping and oil exploration. To provide additional information on the short-term earthquake predictability (retrospective) on oceanic transform faults, we are identifying all magnitude mb >5 earthquakes in our existing hydroacoustic databases and searching for systematic foreshock activity associated with these events. We have multi-year earthquake databases accumulated from past hydrophone experiments along the Central, Southwest and Southeast Indian Ridges, the Juan de Fuca Ridge system, and the northern MAR. Preliminary results are very promising, and there appear to be several examples of clear foreshocks preceding mainshocks by several hours. Also as part of this project, we are compiling a bathymetric map of the equatorial MAR and its transforms between 20N and 10S. There have been several international mapping efforts in this region and the integration of

  15. Downward particle fluxes of biogenic matter and Saharan dust across the equatorial North Atlantic

    NASA Astrophysics Data System (ADS)

    Korte, Laura F.; Brummer, Geert-Jan A.; van der Does, Michèlle; Guerreiro, Catarina V.; Hennekam, Rick; van Hateren, Johannes A.; Jong, Dirk; Munday, Chris I.; Schouten, Stefan; Stuut, Jan-Berend W.

    2017-05-01

    Massive amounts of Saharan dust are blown from the coast of northern Africa across the Atlantic Ocean towards the Americas each year. This dust has, depending on its chemistry, direct and indirect effects on global climate which include reflection and absorption of solar radiation as well as transport and deposition of nutrients and metals fertilizing both ocean and land. To determine the temporal and spatial variability of Saharan dust transport and deposition and their marine environmental effects across the equatorial North Atlantic Ocean, we have set up a monitoring experiment using deep-ocean sediment traps as well as land-based dust collectors. The sediment traps were deployed at five ocean sites along a transatlantic transect between north-west Africa and the Caribbean along 12° N, in a downwind extension of the land-based dust collectors placed at 19° N on the Mauritanian coast in Iouîk. In this paper, we lay out the setup of the monitoring experiment and present the particle fluxes from sediment trap sampling over 24 continuous and synchronized intervals from October 2012 through to November 2013. We establish the temporal distribution of the particle fluxes deposited in the Atlantic and compare chemical compositions with the land-based dust collectors propagating to the downwind sediment trap sites, and with satellite observations of Saharan dust outbreaks. First-year results show that the total mass fluxes in the ocean are highest at the sampling sites in the east and west, closest to the African continent and the Caribbean, respectively. Element ratios reveal that the lithogenic particles deposited nearest to Africa are most similar in composition to the Saharan dust collected in Iouîk. Downwind increasing Al, Fe and K contents suggest a downwind change in the mineralogical composition of Saharan dust and indicate an increasing contribution of clay minerals towards the west. In the westernmost Atlantic Ocean, admixture of re-suspended clay

  16. Isotopic composition of dissolved iron in the Equatorial Pacific and the Southern oceans

    NASA Astrophysics Data System (ADS)

    Radic, A.; Lacan, F.; Jeandel, C.; Poitrasson, F.; Sarthou, G.

    2009-12-01

    Iron is a fundamental element linking ocean biogeochemistry and climate. Iron isotopes are a very promising tool for the study of the iron oceanic cycle, notably for tracing its sources to the ocean and/or for studying its speciation. Several studies reports iron isotopic data in the marine environment: in plankton tows, pore waters, aerosols, seafloor or marginal seas (Bergquist and Boyle, 2006; Severmann et al., 2006; De Jong et al., 2007). To link these isotopic data together and to fully study the iron isotope marine cycle, we need to document the central reservoir in the marine environment : dissolved iron in seawater, espacially in High Nutrient Low Chlorophyll (NHLC) areas. So far there are very few comunicated data of dissolved iron isotopic composition in the open ocean (Rouxel, 2008; Lacan et al., 2008; John and Andkins, 2009;). Here, the first profiles in HNLC areas will be presented : 2 full-depth profiles in the Equatorial Pacific Ocean (EUCFe 2006), 2 full-depth profiles in the Atlantic sector of the Southern Ocean (Bonus-GoodHope 2008) and some data from the Kerguelen area (Southern Ocean, KEOPS 2005). δ56Fe values range from -0.7‰ to more than 1.0‰. All the samples from the Equatorial Pacific Ocean display positive values (heavy iron) whereas samples from the Sourthern Ocean display rather negative values (light iron), especially around 450 m deepth. These results will be discussed in terms of iron sources to ocean. Potential applications of this new tracer for studying internal oceanic processes, such as biological uptake, will be discussed.

  17. Studies of the intermediate and deep circulation in the western equatorial Atlantic

    NASA Technical Reports Server (NTRS)

    Desaubies, Yves; Frankignoul, C.; Merle, Jacques

    1991-01-01

    This proposal concerns the preparation and design of an experiment, the objective of which is to improve our knowledge of the intermediate and deep circulation in the western equatorial Atlantic Ocean. We shall focus on the description of the western boundary currents, of their crossing with the equator, on the estimation of their mass and heat fluxes, and their seasonal and interannual variations. We will use satellite altimetric data, tomographic measurements, and in situ observations (current measurements, hydrology, and floaters). We propose a feasibility study and the definition of a strategy based on a high-resolution Geophysical Fluid Dynamics Laboratory (GFDL) numerical model to define which in situ measurements are necessary to optimally complete the altimetric observations.

  18. Hydrogen in the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Walter, S.; Kock, A.; Steinhoff, T.; Röckmann, T.

    2009-04-01

    Although hydrogen (H2) is considered as one of the most important future energy carriers, little is known about the global biogeochemical cycle of this trace gas (Rhee et al. 2006). In order to assess the potential impact of expected increasing H2 concentrations to the atmosphere a fundamental understanding of the global H2 cycle is indispensable (Tromp et al. 2003, Warwick et al. 2004). Oceans are one source of atmospheric H2, produced by biological processes such as fermentation and N2-fixation and abiotic photochemical processes (Punshon and Moore 2008 and references herein). Further information can be obtained by studying the isotope composition of H2. However, the isotopic ratio of oceanic released H2 is unknown and has so far only been estimated from thermodynamic equilibrium. We investigated the atmospheric D/H isotopic ratio of H2 in the Atlantic Ocean. First results of atmospheric H2 isotope ratios from the West African coast of Mauritania and from a meridional transect over the Atlantic Ocean will be presented. Samples were taken onboard the German research vessel "Poseidon" in February 2007 associated to SOPRAN and during the cruise Ant XXIV-4 with the German research vessel "Polarstern" in April 2008 between Punta Arenas (Chile) and Bremerhaven (Germany). Literature Punshon, S. and R.M. Moore; Aerobic hydrogen production and dinitrogen fixation in the marine cyanobacterium Trichodesmium erythraeum IMS101; Limnol. Oceanogr., 53(6), 2749-2753, 2008. Rhee, T.S., C.A.M. Brenninkmeijer, and T. Röckmann; The overwhelming role of soils in the global atmospheric hydrogen cycle, Atmos. Chem. Phys., 6, 1611-1625, 2006. Tromp, T.K., Shi, R.-L., Allen, M., Eiler, J.M., and Y. L. Yung1; Potential Environmental Impact of a Hydrogen Economy on the Stratosphere, Science, 300, 1740-1742, 2003. Warwick, N.J., Bekki, S., Nisbet, E.G., and J.A. Pyle; Impact of a hydrogen economy on the stratosphere and troposphere studied in a 2-D model; Geo.Res.Lett., 31, L05107, doi:10

  19. Wet deposition of trace elements and radon daughter systematics in the South and equatorial Atlantic atmosphere

    NASA Astrophysics Data System (ADS)

    Kim, Guebuem; Church, Thomas M.

    2002-09-01

    Atmospheric samples were collected aboard ship in the South and equatorial Atlantic (35°S-10°N) between 19 May and 20 June 1996. We measured 222Rn in air, 210Pb in aerosol, and trace elements (Fe, Mn, Zn, Pb, Cu, Cd, Ni, and Cr), 210Pb, and 210Po in precipitation samples. The large variation of 222Rn in air suggests a significant change in the incursion of continental air with time and latitude in the remote Atlantic. In the equatorial and subtropical Atlantic (20°S-10°N), 222Rn activity was lower but 210Pb/222Rn ratios were higher than those at higher latitudes. The higher 210Pb/222Rn ratios in the equatorial Atlantic appear to be due to prevailing trade easterly winds which transport a supported source of 210Pb in Saharan dust from the African Sahel. The enrichment of noncrustal trace elements in precipitation samples from the remote equatorial Atlantic was small on account of the remoteness from the continental emission regions and as a result of dilution with Saharan dust. The wet depositional fluxes of major crustal elements (Fe and Mn) were two- to three-fold higher, while those of Cd and Zn were two- to ten-fold lower, in the South and equatorial Atlantic relative to the western North Atlantic (Bermuda) or North Atlantic coast (Lewes, Delaware). Thus, dominant wet precipitation of Saharan dust in the Intertropical Convergence Zone (ITCZ) areas of the equatorial Atlantic appears to be a large potential source of micronutrients (i.e., Fe) to surface seawater.

  20. 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.

  1. Westward propagating twin gyres in the equatorial Indian Ocean

    NASA Astrophysics Data System (ADS)

    Reddy, P. Rahul Chand; Salvekar, P. S.; Deo, A. A.; Ganer, D. W.

    2004-01-01

    A reduced-gravity (1$\\frac{1}{2-layer) model forced by daily climatological winds simulates twin, anticyclonic gyres, which propagate westward on either side of the equator. The gyres form at the beginning of both the Southwest Monsoon and the Northeast monsoon in the equatorial eastern Indian Ocean, and subsequently propagate across the basin. Their existence is supported by velocity observations taken during WOCE in 1995 and by TOPEX/Poseidon sea-level observations during 1993. They are also present in the ECCO model/data product. They form at the front of a Rossby-wave packet generated by the reflection of the equatorial jet (EJ) from the eastern boundary of the basin. They are likely either Rossby solitons or result from the nonlinear interaction between the EJ and the Rossby-wave front.

  2. 76 FR 31235 - Safety Zone; Ocean City Air Show, Atlantic Ocean, Ocean City, MD

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-31

    ... establish a temporary safety zone on the Atlantic Ocean 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... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Ocean City Air Show, Atlantic Ocean,...

  3. Seasonal sea surface cooling in the equatorial Pacific cold tongue controlled by ocean mixing.

    PubMed

    Moum, James N; Perlin, Alexander; Nash, Jonathan D; McPhaden, Michael J

    2013-08-01

    Sea surface temperature (SST) is a critical control on the atmosphere, and numerical models of atmosphere-ocean circulation emphasize its accurate prediction. Yet many models demonstrate large, systematic biases in simulated SST in the equatorial 'cold tongues' (expansive regions of net heat uptake from the atmosphere) of the Atlantic and Pacific oceans, particularly with regard to a central but little-understood feature of tropical oceans: a strong seasonal cycle. The biases may be related to the inability of models to constrain turbulent mixing realistically, given that turbulent mixing, combined with seasonal variations in atmospheric heating, determines SST. In temperate oceans, the seasonal SST cycle is clearly related to varying solar heating; in the tropics, however, SSTs vary seasonally in the absence of similar variations in solar inputs. Turbulent mixing has long been a likely explanation, but firm, long-term observational evidence has been absent. Here we show the existence of a distinctive seasonal cycle of subsurface cooling via mixing in the equatorial Pacific cold tongue, using multi-year measurements of turbulence in the ocean. In boreal spring, SST rises by 2 kelvin when heating of the upper ocean by the atmosphere exceeds cooling by mixing from below. In boreal summer, SST decreases because cooling from below exceeds heating from above. When the effects of lateral advection are considered, the magnitude of summer cooling via mixing (4 kelvin per month) is equivalent to that required to counter the heating terms. These results provide quantitative assessment of how mixing varies on timescales longer than a few weeks, clearly showing its controlling influence on seasonal cooling of SST in a critical oceanic regime.

  4. Dinocyst assemblage constraints on oceanographic and atmospheric processes in the eastern equatorial Atlantic over the last 44 kyr

    NASA Astrophysics Data System (ADS)

    Hardy, William; Penaud, Aurélie; Marret, Fabienne; Bayon, Germain; Marsset, Tania; Droz, Laurence

    2016-08-01

    A new 44 kyr long record of dinoflagellate (phytoplanktonic organisms) cysts (dinocysts) is presented from a marine sediment core collected on the Congolese margin with the aim of reconstructing past hydrological changes in the equatorial eastern Atlantic Ocean since Marine Isotopic Stage (MIS) 3. Our high-resolution dinocyst record indicates that significant temperature and moisture variations occurred across the glacial period, the last deglaciation and the Holocene. The use of specific dinocyst taxa, indicative of fluvial, upwelling and Benguela Current past environments for instance, provides insights into the main forcing mechanisms controlling palaeohydrological changes on orbital timescales. In particular, we are able, for the last 44 kyr, to correlate fluvial-sensitive taxa to monsoonal mechanisms related to precession minima-obliquity maxima combinations. While upwelling mechanisms appear as the main drivers for dinoflagellate productivity during MIS 2, dissolved nutrient-enriched Congo River inputs to the ocean also played a significant role in promoting dinoflagellate productivity between approximately 15.5 and 5 ka BP. Finally, this high-resolution dinocyst study permits us to precisely investigate the suborbital timing of the last glacial-interglacial termination, including an atypical warm and wet oceanic LGM signature, northern high-latitude abrupt climate change impacts in the equatorial eastern Atlantic, as well as a two-step decrease in moisture conditions during the Holocene at around 7-6 and 4-3.5 ka BP.

  5. 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.

  6. 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.

  7. Modeling Mesoscale Eddies in the North Atlantic Ocean

    NASA Technical Reports Server (NTRS)

    Chao, Yi

    1999-01-01

    Ocean modeling plays an important role in understanding the current climatic conditions and predicting the future climate change. Modeling the ocean at eddy-permitting and/or eddy resolving resolutions (1/3 degree or higher) has a two-fold objective. One part is to represent the ocean as realistically as possible, because mesoscale eddies have an impact on the large-scale circulation. The second objective is to learn how to represent effects of mesoscale eddies without explicitly resolving them. This is particularly important for climate models which cannot be run at eddy-resolving resolutions because of the computational constraints. At JPL, a 1/6 degree latitude by 1/6 degree longitude with 37 vertical levels Atlantic Ocean model has been developed. The model is based on the Parallel Ocean Program (POP) developed at Los Alamos National Laboratory (LANL). Using the 256-processor Cray T3D, we have conducted a 40-year integration of this Atlantic eddy-resolving ocean model. A regional analysis demonstrate that many observed features associated with the Caribbean Sea eddies can be realistically simulated by this model. Analysis of this Atlantic eddy-resolving ocean model further suggests that these Caribbean Sea eddies are connected with eddies formed outside the Caribbean Sea at the confluence of the North Brazil Current (NBC) and the North Equatorial Countercurrent. The diagram of the model simulated surface current shows that the Caribbean eddies ultimately originate in the NBC retroflection region, traveling more than a year from the North Brazil coast through the Lesser Antilles into the Caribbean Sea and eventually into the Gulf of Mexico. Additional information is contained in the original.

  8. The Cretaceous opening of the South Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Granot, Roi; Dyment, Jérôme

    2015-03-01

    The separation of South America from Africa during the Cretaceous is poorly understood due to the long period of stable polarity of the geomagnetic field, the Cretaceous Normal Superchron (CNS, lasted between ∼121 and 83.6 Myr ago). We present a new identification of magnetic anomalies located within the southern South Atlantic magnetic quiet zones that have arisen due to past variations in the strength of the dipolar geomagnetic field. Using these anomalies, together with fracture zone locations, we calculate the first set of magnetic anomalies-based finite rotation parameters for South America and Africa during that period. The kinematic solutions are generally consistent with fracture zone traces and magnetic anomalies outside the area used to construct them. The rotations indicate that seafloor spreading rates increased steadily throughout most of the Cretaceous and decreased sharply at around 80 Myr ago. A change in plate motion took place in the middle of the superchron, roughly 100 Myr ago, around the time of the final breakup (i.e., separation of continental-oceanic boundary in the Equatorial Atlantic). Prominent misfit between the calculated synthetic flowlines (older than Anomaly Q1) and the fracture zones straddling the African Plate in the central South Atlantic could only be explained by a combination of seafloor asymmetry and internal dextral motion (<100 km) within South America, west of the Rio Grande fracture zone. This process has lasted until ∼92 Myr ago after which both Africa and South America (south of the equator) behaved rigidly. The clearing of the continental-oceanic boundaries within the Equatorial Atlantic Gateway was probably completed by ∼95 Myr ago. The clearing was followed by a progressive widening and deepening of the passageway, leading to the emergence of north-south flow of intermediate and deep-water which might have triggered the global cooling of bottom water and the end for the Cretaceous greenhouse period.

  9. Biogeography and potential exchanges among the atlantic Equatorial belt cold-seep faunas.

    PubMed

    Olu, Karine; Cordes, Erik E; Fisher, Charles R; Brooks, James M; Sibuet, Myriam; Desbruyères, Daniel

    2010-08-05

    Like hydrothermal vents along oceanic ridges, cold seeps are patchy and isolated ecosystems along continental margins, extending from bathyal to abyssal depths. The Atlantic Equatorial Belt (AEB), from the Gulf of Mexico to the Gulf of Guinea, was one focus of the Census of Marine Life ChEss (Chemosynthetic Ecosystems) program to study biogeography of seep and vent fauna. We present a review and analysis of collections from five seep regions along the AEB: the Gulf of Mexico where extensive faunal sampling has been conducted from 400 to 3300 m, the Barbados accretionary prism, the Blake ridge diapir, and in the Eastern Atlantic from the Congo and Gabon margins and the recently explored Nigeria margin. Of the 72 taxa identified at the species level, a total of 9 species or species complexes are identified as amphi-Atlantic. Similarity analyses based on both Bray Curtis and Hellinger distances among 9 faunal collections, and principal component analysis based on presence/absence of megafauna species at these sites, suggest that within the AEB seep megafauna community structure is influenced primarily by depth rather than by geographic distance. Depth segregation is observed between 1000 and 2000 m, with the middle slope sites either grouped with those deeper than 2000 m or with the shallower sites. The highest level of community similarity was found between the seeps of the Florida escarpment and Congo margin. In the western Atlantic, the highest degree of similarity is observed between the shallowest sites of the Barbados prism and of the Louisiana slope. The high number of amphi-atlantic cold-seep species that do not cluster according to biogeographic regions, and the importance of depth in structuring AEB cold-seep communities are the major conclusions of this study. The hydrothermal vent sites along the Mid Atlantic Ridge (MAR) did not appear as "stepping stones" for dispersal of the AEB seep fauna, however, the south MAR and off axis regions should be further

  10. Biogeography and Potential Exchanges Among the Atlantic Equatorial Belt Cold-Seep Faunas

    PubMed Central

    Olu, Karine; Cordes, Erik E.; Fisher, Charles R.; Brooks, James M.; Sibuet, Myriam; Desbruyères, Daniel

    2010-01-01

    Like hydrothermal vents along oceanic ridges, cold seeps are patchy and isolated ecosystems along continental margins, extending from bathyal to abyssal depths. The Atlantic Equatorial Belt (AEB), from the Gulf of Mexico to the Gulf of Guinea, was one focus of the Census of Marine Life ChEss (Chemosynthetic Ecosystems) program to study biogeography of seep and vent fauna. We present a review and analysis of collections from five seep regions along the AEB: the Gulf of Mexico where extensive faunal sampling has been conducted from 400 to 3300m, the Barbados accretionary prism, the Blake ridge diapir, and in the Eastern Atlantic from the Congo and Gabon margins and the recently explored Nigeria margin. Of the 72 taxa identified at the species level, a total of 9 species or species complexes are identified as amphi-Atlantic. Similarity analyses based on both Bray Curtis and Hellinger distances among 9 faunal collections, and principal component analysis based on presence/absence of megafauna species at these sites, suggest that within the AEB seep megafauna community structure is influenced primarily by depth rather than by geographic distance. Depth segregation is observed between 1000 and 2000m, with the middle slope sites either grouped with those deeper than 2000m or with the shallower sites. The highest level of community similarity was found between the seeps of the Florida escarpment and Congo margin. In the western Atlantic, the highest degree of similarity is observed between the shallowest sites of the Barbados prism and of the Louisiana slope. The high number of amphi-atlantic cold-seep species that do not cluster according to biogeographic regions, and the importance of depth in structuring AEB cold-seep communities are the major conclusions of this study. The hydrothermal vent sites along the Mid Atlantic Ridge (MAR) did not appear as “stepping stones” for dispersal of the AEB seep fauna, however, the south MAR and off axis regions should be further

  11. 75 FR 18778 - Safety Zone; Ocean City Air Show 2010, Atlantic Ocean, Ocean City, MD

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-13

    ... to support the Ocean City Air Show. This action is intended to restrict vessel traffic movement on the Atlantic Ocean to protect mariners and the public from the hazards associated with air show events... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Ocean City Air Show 2010, Atlantic Ocean...

  12. Strong middepth warming and weak radiocarbon imprints in the equatorial Atlantic during Heinrich 1 and Younger Dryas

    NASA Astrophysics Data System (ADS)

    Weldeab, Syee; Friedrich, Tobias; Timmermann, Axel; Schneider, Ralph R.

    2016-08-01

    We present a benthic foraminiferal multiproxy record of eastern equatorial Atlantic (EEA) middepth water (1295 m) covering the last deglacial. We show that EEA middepth water temperatures were elevated by 3.9 ± 0.5°C and 5.2 ± 1.2°C during Heinrich event 1 (H1) and Younger Dryas (YD), respectively. The radiocarbon content of the EEA middepth during H1 and YD is relatively low and comparable to the values of the pre-H1 episode and Bølling-Allerød, respectively. A transient Earth system model simulation, which mimics the observed deglacial Atlantic Meridional Overturning Circulation (AMOC) history, qualitatively reproduces the major features of the EEA proxy records. The simulation results suggest that fresh water-induced weakening of the AMOC leads to a vertical shift of the horizon of Southern Ocean-sourced water and a stronger influence of EEA sea surface temperatures via mixing. Our findings reaffirm the lack of a distinctive signature of radiocarbon depletion and therefore do not support the notion of interhemispheric exchanges of strongly radiocarbon-depleted middepth water across the tropical Atlantic during H1 and YD. Our temperature reconstruction presents a critical zonal and water depth extension of existing tropical Atlantic data and documents a large-scale and basin-wide warming across the thermocline and middepth of the tropical Atlantic during H1 and YD. Significant difference in the timing and pace of H1 middepth warming between tropical Atlantic and North Atlantic likely points to a limited role of the tropical Atlantic middepth warming in the rapid heat buildup in the North Atlantic middepth.

  13. Iron limitation of phytoplankton photosynthesis in the equatorial Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Kolber, Zbigniew S.; Barber, Richard T.; Coale, Kenneth H.; Fitzwateri, Steve E.; Greene, Richard M.; Johnson, Kenneth S.; Lindley, Steven; Falkowski, Paul G.

    1994-09-01

    THE surface waters of the equatorial Pacific have unusually high nitrate and phosphate concentrations, but relatively low phyto-plankton biomass1-3. This 'high nitrate, low chlorophyll' (HNLC)4 phenomenon has been ascribed to 'top-down' grazing pressure by herbivores, which prevent the phytoplankton from fully utilizing the available nutrients5. In the late 1980s, however, Martin and co-workers proposed that iron, which is delivered to the remote open ocean in aeolean dust6, is the key factor limiting the standing crop of phytoplankton in HNLC areas7,8. Using a sensitive fluor-escence method9, we have followed changes in photochemical energy conversion efficiency9-10 of the natural phytoplankton com-munity both before and after artificial enrichment with iron of a small area (7.5 x 7.5 km) of the equatorial Pacific Ocean11. Our results show that iron limits phytoplankton photosynthesis in all size classes in this region by impairing intrinsic photochemical energy conversion, thereby supporting the hypothesis of physiologi-cal ('bottom up') limitation by this element.

  14. The sources of deep ocean infragravity waves observed in the North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Crawford, Wayne; Ballu, Valerie; Bertin, Xavier; Karpytchev, Mikhail

    2015-07-01

    Infragravity waves are long-period (25-250 s) ocean surface gravity waves generated in coastal zones through wave-wave interactions or oscillation of the breaking point. Most of the infragravity wave energy is trapped or dissipated near coastlines, but a small percentage escapes into the open oceans. The source of deep ocean infragravity waves is debated, specifically whether they come mostly from regions with strong source waves or from sites with particular morphologies/orientations. We correlate measurements of infragravity waves in the deep North Atlantic Ocean with infragravity wave generation parameters throughout the Atlantic Ocean to find the dominant sources of deep ocean infragravity wave energy in the North Atlantic Ocean. The deep ocean infragravity wave data are from a 5 year deployment of absolute pressure gauges west of the Azores islands (37°N, 35°W) and shorter data sets from seafloor tsunami gauges (DART buoys). Two main sources are identified: one off of the west coast of southern Europe and northern Africa (25°N-40°N) in northern hemisphere winter and the other off the west coast of equatorial Africa (the Gulf of Guinea) in southern hemisphere winter. These regions have relatively weak source waves and weak infragravity wave propagation paths to the main measurement site, indicating that that the site morphology/orientation dominates the creation of deep ocean infragravity waves. Both regions have also been identified as potential sources of global seismological noise, suggesting that the same mechanisms may be behind the generation of deep ocean infragravity waves and global seismological noise in the frequency band from 0.001 to 0.04 Hz.

  15. Atmospheric Blocking and Atlantic Multidecadal 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, which involves isolation of large regions of air from the westerly circulation for 5 days or more, influences fundamentally the ocean circulation and upper ocean properties by affecting wind patterns. Winters with clusters of more frequent blocking between Greenland and western Europe correspond to a warmer, more saline subpolar ocean. The correspondence between blocked westerly winds and warm ocean holds in recent decadal episodes (especially 1996 to 2010). It also describes much longer time scale Atlantic multidecadal ocean variability (AMV), including the extreme pre-greenhouse-gas northern warming of the 1930s to 1960s. The space-time structure of the wind forcing associated with a blocked regime leads to weaker ocean gyres and weaker heat exchange, both of which contribute to the warm phase of AMV.

  16. Atmospheric blocking and Atlantic multidecadal ocean variability.

    PubMed

    Häkkinen, Sirpa; Rhines, Peter B; Worthen, Denise L

    2011-11-04

    Atmospheric blocking over the northern North Atlantic, which involves isolation of large regions of air from the westerly circulation for 5 days or more, influences fundamentally the ocean circulation and upper ocean properties by affecting wind patterns. Winters with clusters of more frequent blocking between Greenland and western Europe correspond to a warmer, more saline subpolar ocean. The correspondence between blocked westerly winds and warm ocean holds in recent decadal episodes (especially 1996 to 2010). It also describes much longer time scale Atlantic multidecadal ocean variability (AMV), including the extreme pre-greenhouse-gas northern warming of the 1930s to 1960s. The space-time structure of the wind forcing associated with a blocked regime leads to weaker ocean gyres and weaker heat exchange, both of which contribute to the warm phase of AMV.

  17. Atmospheric Blocking and Atlantic Multidecadal 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, which involves isolation of large regions of air from the westerly circulation for 5 days or more, influences fundamentally the ocean circulation and upper ocean properties by affecting wind patterns. Winters with clusters of more frequent blocking between Greenland and western Europe correspond to a warmer, more saline subpolar ocean. The correspondence between blocked westerly winds and warm ocean holds in recent decadal episodes (especially 1996 to 2010). It also describes much longer time scale Atlantic multidecadal ocean variability (AMV), including the extreme pre-greenhouse-gas northern warming of the 1930s to 1960s. The space-time structure of the wind forcing associated with a blocked regime leads to weaker ocean gyres and weaker heat exchange, both of which contribute to the warm phase of AMV.

  18. Chlorofluoromethane distributions in the deep equatorial Atlantic during January-March 1993

    NASA Astrophysics Data System (ADS)

    Andrié, Chantal; Ternon, Jean-Fran çois; Messias, Marie-José; Memery, Laurent; Bourlès, Bernard

    1998-06-01

    Chlorofluoromethanes were sampled along two zonal sections, at 4°30 S and 7°30 N between the African and American continents (A7 and A6 WOCE sections) and two meridional sections, at 35°W and 3°50W, during the CITHER 1 cruise (part of the French program CITHER (CIrculation THERmohaline) during January-March 1993. The results reported here deal primarily with the North Atlantic Deep Water, just ten years after the first CFM snapshot of the tropical Atlantic ocean obtained during the Transient Tracers in the Ocean Program (TTO) ( Weiss et al., 1985. Nature 314, 608-610). The data provide evidence for the eastward bifurcation of the deep flow near the equator, on both UNADW and LNADW levels. The distributions clearly show the CFM signal corresponding to the UNADW penetrating into the eastern basin: at 3°50W the CFM core extends from 4°S to 3°N with a maximum around 2°S. On both UNADW and LNADW levels, the bifurcation does not occur exactly on the equator but a few degrees south and seems to be partly induced by topographic effects. Previously published circulation schemes for UNADW and LNADW levels are compared to the CITHER 1 CFM data. Great variability is revealed and new patterns from the data are highlighted. The "young" deep component of the AABW flow seems to be stopped by the topography just north of the equatorial channel. TTO and CITHER 1 data set comparison and "apparent" ages lead to minimal values of the propagation rate of the CFC signal at low latitudes.

  19. Carbon disulfide measurements in the atmosphere of the western North Atlantic and the northwestern South Atlantic Oceans

    NASA Technical Reports Server (NTRS)

    Bandy, Alan R.; Thornton, Donald C.; Johnson, James E.

    1993-01-01

    Carbon disulfide (CS2) measurements were made over the western and equatorial North Atlantic Ocean and the northwestern and equatorial South Atlantic Ocean. Carbon disulfide was in the range 0.4-50 pptrv in the atmosphere of the western North Atlantic Ocean. Emissions from anthropogenic sources and wet lands were found to be important although anthropogenic sources were 4-6 times larger than biogenic sources. The flux of CS2 from eastern North America between 30 and 39 deg latitude was estimated to be 2 x 10(exp 8)g/yr or sulfur. The anthropogenic contribution was 1.8 x 10(exp 8)g/yr of sulfur whereas the contribution of marshes was 0.2 x 10(exp 8)g/yr of sulfur. Sources of CS2 at high latitudes in the northern hemisphere were comparatively weak. Carbon disulfide levels in the western South Atlantic Ocean between -5 and 1 deg latitude were in the range 0.2-6 pptrv. Most of the CS2 appeared to come from biomass burning in Africa. Carbon disulfide was much higher close to shore suggesting that the South American continent was a significant source although too few data were available to quantify it. On ferry lights from Wallops, Virginia to Natal, Brazil, CS2 levels at the ferry altitude of about 6 km averaged 1.2 pptrv. This background CS2 was adequate to account for all the carbonyl sulfide (OCS) in the atmosphere.

  20. Rapid ocean wave teleconnections linking Antarctic salinity anomalies to the equatorial ocean-atmosphere system

    NASA Astrophysics Data System (ADS)

    Atkinson, C. P.; Wells, N. C.; Blaker, A. T.; Sinha, B.; Ivchenko, V. O.

    2009-04-01

    The coupled climate model FORTE is used to investigate rapid ocean teleconnections between the Southern Ocean and equatorial Pacific Ocean. Salinity anomalies located throughout the Southern Ocean generate barotropic signals that propagate along submerged topographic features and result in the growth of baroclinic energy anomalies around Indonesia and the tropical Pacific. Anomalies in the Ross, Bellingshausen and Amundsen Seas exchange the most barotropic kinetic energy between high and low latitudes. In the equatorial Pacific, baroclinic Kelvin waves are excited which propagate eastwards along the thermocline, resulting in SST anomalies in the central and eastern Pacific. SST anomalies are subsequently amplified to magnitudes of 1.25°C by air-sea interaction, which could potentially influence other coupled Pacific phenomena.

  1. Intraseasonal mixed-layer heat budget in the equatorial Atlantic during the cold tongue development in 2006

    NASA Astrophysics Data System (ADS)

    Giordani, Hervé; Caniaux, Guy; Voldoire, Aurore

    2013-02-01

    Estimating the mixed-layer heat budget is a key issue for understanding the cold tongue development in the eastern equatorial Atlantic. A high-resolution ocean regional model is used to diagnose the mixed-layer heat budget online during the EGEE-3 experiment from May to August 2006. The heat budget shows the major role of the horizontal advection and turbulent mixing in the mixed-layer temperature balance in the cold tongue. The surface net heat flux and entrainment processes play a minor role. The equatorial cooling is mainly induced by low-frequency advection, which is balanced by high-frequency zonal and meridional advections. The high-frequency advections are organized in patterns along the northern edge of the cold tongue, where they are associated with strong sea surface temperature gradients and well-developed tropical instability waves in the western Atlantic. Special attention is paid to the wind energy flux, which controls horizontal advection and turbulent mixing. We suggest that the wind energy flux drives the vertical velocity, which in turn adjusts the mixed-layer depth, its stratification, and the vertical shear of the horizontal current. Although vertical advection is not essential in providing cold water in the Atlantic cold tongue, it is shown that the vertical velocity plays a central role in preconditioning the mixed layer and maximizes the turbulent mixing.

  2. Atlantic and Indian Oceans Pollution in Africa

    NASA Astrophysics Data System (ADS)

    Abubakar, B.

    2007-05-01

    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

  3. 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.

  4. Estimates of the zonal slope and seasonal transport of the Atlantic North Equatorial Countercurrent

    NASA Technical Reports Server (NTRS)

    Carton, James A.; Katz, Eli J.

    1990-01-01

    Data from six inverted echo sounder moorings and the Geosat satellite altimeter are used to examine the seasonal variability of sea surface elevation. Monthly sea level maps are constructed using a contemporaneous subsurface temperature survey to provide a reference sea level field. The maps are then used to describe the origin and structure of the western tropical Atlantic North Equatorial Countercurrent (NECC) during a two-year period beginning in November 1987. The data reveal a zonal current which is confined between 3 deg N and 9 deg N with a typical width of 300 km. The NECC flows strongly eastward during November and December 1986 and May 1987 through January 1988. The reappearance of the current is then delayed until August, but the current flows strongly from August until the end of the record in October 1988. Volume transport is estimated for the two-year period from surface elevation by approximating the vertical structure of the ocean as a two-layer fluid. It is found that the NECC has a maximum transport of 40 x 10 to the 6th cu m/s at 38 deg W.

  5. 50 CFR 600.520 - Northwest Atlantic Ocean fishery.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 12 2012-10-01 2012-10-01 false Northwest Atlantic Ocean fishery. 600.520... Northwest Atlantic Ocean fishery. (a) Purpose. Sections 600.520 and 600.525 regulate all foreign fishing conducted under a GIFA within the EEZ in the Atlantic Ocean north of 35°00′ N. lat. (b) Authorized fishery...

  6. 50 CFR 600.520 - Northwest Atlantic Ocean fishery.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false Northwest Atlantic Ocean fishery. 600.520... Northwest Atlantic Ocean fishery. (a) Purpose. Sections 600.520 and 600.525 regulate all foreign fishing conducted under a GIFA within the EEZ in the Atlantic Ocean north of 35°00′ N. lat. (b) Authorized fishery...

  7. 50 CFR 600.520 - Northwest Atlantic Ocean fishery.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 10 2011-10-01 2011-10-01 false Northwest Atlantic Ocean fishery. 600.520... Northwest Atlantic Ocean fishery. (a) Purpose. Sections 600.520 and 600.525 regulate all foreign fishing conducted under a GIFA within the EEZ in the Atlantic Ocean north of 35°00′ N. lat. (b) Authorized fishery...

  8. 50 CFR 600.520 - Northwest Atlantic Ocean fishery.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 12 2014-10-01 2014-10-01 false Northwest Atlantic Ocean fishery. 600.520... Northwest Atlantic Ocean fishery. (a) Purpose. Sections 600.520 and 600.525 regulate all foreign fishing conducted under a GIFA within the EEZ in the Atlantic Ocean north of 35°00′ N. lat. (b) Authorized fishery...

  9. Impact of Indian Ocean Dipole on the salinity budget in the equatorial Indian Ocean

    NASA Astrophysics Data System (ADS)

    DU, Y.; Zhang, Y.

    2013-12-01

    Based on ocean reanalysis data sets and observations, this study analyzes the variability of salinity and its associated ocean dynamics in the equatorial Indian Ocean (IO). The results show that significant interannual variability of salinity in boreal fall are mainly associated with the Indian Ocean dipole (IOD) events, especially the positive IOD (pIOD) events. During pIOD events, forced by anomalous easterly winds, westward current anomalies strengthen the westward advection in summer and weaken the eastward advection of Wyrtki Jets in fall. Analysis of salinity budget indicates that salinity anomalies are mainly dominated by advection, in which zonal component is the key. As the zonal current anomalies are symmetric off the equator, mean zonal salinity gradients dominate the asymmetric distribution of low-salinity advection. Low-salinity water advects to the west, shoals mixed layer, favoring SST increasing after the mature phase of pIOD. After the decay phase, low-salinity water advects across the equator to the southwestern IO, which associates with the off-equatorial anticyclonic circulations in the southern IO. When pIOD events concur with El Niño, the low-salinity water advection strengthens and advects northward and southward simultaneously after the decay phase, due to the strong off-equatorial influence from El Niño.

  10. Equatorial Indian Ocean subsurface current variability in an Ocean General Circulation Model

    NASA Astrophysics Data System (ADS)

    Gnanaseelan, C.; Deshpande, Aditi

    2017-05-01

    The variability of subsurface currents in the equatorial Indian Ocean is studied using high resolution Ocean General Circulation Model (OGCM) simulations during 1958-2009. February-March eastward equatorial subsurface current (ESC) shows weak variability whereas strong variability is observed in northern summer and fall ESC. An eastward subsurface current with maximum amplitude in the pycnocline is prominent right from summer to winter during strong Indian Ocean Dipole (IOD) years when air-sea coupling is significant. On the other hand during weak IOD years, both the air-sea coupling and the ESC are weak. This strongly suggests the role of ESC on the strength of IOD. The extension of the ESC to the summer months during the strong IOD years strengthens the oceanic response and supports intensification and maintenance of IODs through modulation of air sea coupling. Although the ESC is triggered by equatorial winds, the coupled air-sea interaction associated with IODs strengthens the ESC to persist for several seasons thereby establishing a positive feedback cycle with the surface. This suggests that the ESC plays a significant role in the coupled processes associated with the evolution and intensification of IOD events by cooling the eastern basin and strengthening thermocline-SST (sea surface temperature) interaction. As the impact of IOD events on Indian summer monsoon is significant only during strong IOD years, understanding and monitoring the evolution of ESC during these years is important for summer monsoon forecasting purposes. There is a westward phase propagation of anomalous subsurface currents which persists for a year during strong IOD years, whereas such persistence or phase propagation is not seen during weak IOD years, supporting the close association between ESC and strength of air sea coupling during strong IOD years. In this study we report the processes which strengthen the IOD events and the air sea coupling associated with IOD. It also unravels

  11. 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

  12. Deep currents and the eastward salinity tongue in the equatorial Atlantic: Results from an eddy-resolving, primitive equation model

    SciTech Connect

    Boening, C.W.; Schott, F.A. )

    1993-04-15

    The authors study the time and spatial dependence of the velocity of deep water circulation in the equatorial Atlantic by using a high resolution model of the wind-driven and thermohaline circulation. The model is the [open quotes]community modeling effort[close quotes], developed for the World Ocean Circulation Experiment, which is here extended to look at deeper waters. In the Atlantic, the North Atlantic Deep Water (NADW) spreads cold, saline water south, the majority of which is carried in the deep western boundary current (DWBC), and this flow is compensated by northward motion of warmer surface waters. The actual flow velocities and patterns of this deep flow water are not well known, or well modelled at present. Salinity measurements indicate a major east west flow of deep water at the equator. The authors extend this ocean circulation model to deeper waters to try to address such flow questions, given surface wind forcing, and thermohaline circulation. The sparse experimental data indicates the presence of zonal currents at different depths, but such little data is available that it is difficult to assess the bearing this should have on model predictions.

  13. Silver in the far North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Rivera-Duarte, I.; Flegal, A. R.; Sañudo-Wilhelmy, S. A.; Véron, A. J.

    Total (unfiltered) silver concentrations in higher latitudes of the North Atlantic (52-68°N) are reported for the second Intergovernmental Oceanographic Commission (IOC) Global Investigation of Pollutants in the Marine Environment (GIPME) baseline survey of 1993. These silver concentrations (0.69-7.2 pM) are oceanographically consistent with those (0.24-9.6 pM) previously reported for lower latitudes in the eastern North and South Atlantic ( Flegal et al., 1995). However, surface (⩽200 m) water concentrations of silver (0.69-4.6 pM) in the northern North Atlantic waters are, on average, ten-fold larger than those (0.25 pM) considered natural background concentrations in surface waters of the central Atlantic. In contrast, variations in deep far North Atlantic silver concentrations are associated with discrete water masses. Consequently, the cycling of silver in the far North Atlantic appears to be predominantly controlled by external inputs and the advection of distinct water masses, in contrast to the nutrient-like biogeochemical cycling of silver observed in the central Atlantic and Pacific oceans.

  14. 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

  15. Anisotropic tomography of the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Silveira, Graça.; Stutzmann, Eléonore

    2002-10-01

    We present the first regional three-dimensional model of the Atlantic Ocean with anisotropy. The model, derived from Rayleigh and Love wave 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 (MAR) 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 300 km depth, they are much broader than 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

  16. Radiocarbon evidence for a possible abyssal front near 3.1 km in the glacial equatorial Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Keigwin, L. D.; Lehman, S. J.

    2015-09-01

    We investigate the radiocarbon ventilation age in deep equatorial Pacific sediment cores using the difference in conventional 14C age between coexisting benthic and planktonic foraminifera, and integrate those results with similar data from around the North Pacific Ocean in a reconstruction for the last glaciation (15 to 25 conventional 14C ka). Most new data from both the Equatorial Pacific and the Emperor Seamounts in the northwestern Pacific come from maxima in abundance of benthic taxa because this strategy reduces the effect of bioturbation. Although there remains considerable scatter in the ventilation age estimates, on average, ventilation ages in the Equatorial Pacific were significantly greater below 3.2 km (∼ 3080 ± 1125 yrs, n = 15) than in the depth interval 1.9 to 3.0 km (∼ 1610 ± 250 yrs, n = 12). When compared to the average modern seawater Δ14C profile for the North Pacific, the Equatorial Pacific glacial data suggest an abyssal front located somewhere between 3.0 and 3.2 km modern water depth. Above that depth, the data may indicate slightly better ventilation than today, and below that depth, glacial Equatorial Pacific data appear to be as old as last glacial maximum (LGM) deep water ages reported for the deep southern Atlantic. This suggests that a glacial reservoir of aged waters extended throughout the circumpolar Southern Ocean and into the Equatorial Pacific. Renewed ventilation of such a large volume of aged (and, by corollary, carbon-rich) water would help to account for the rise in atmospheric pCO2 and the fall in Δ14C as the glaciation drew to a close.

  17. An Analysis of the ENSO Signal in the Tropical Atlantic and Western Indian Oceans

    NASA Astrophysics Data System (ADS)

    Nicholson, Sharon E.

    1997-03-01

    This article examines the time-space evolution of the El Niño-Southern Oscillation (ENSO) signal in the tropical Atlantic and western Indian Oceans, using harmonic analysis. Composites of sea-surface temperatures (SSTs) and other variables are examined for a 24-month period beginning 6 months prior to the year of maximum warming in the Pacific (termed year 0). An ENSO signal is apparent in the Atlantic in six out of eight Pacific episodes and in the Indian Ocean in all eight episodes. Warming begins along the south-eastern Atlantic coast early in year 0, some months later elsewhere in the Atlantic and in the Indian Ocean. Maximum warming occurs in the Atlantic in October-December of year 0, but in the following January-March in the Indian Ocean.In these oceans a cold phase occurs synchronously with the first half of the Pacific episode (July of year -1 to June of year 0, in the Rasmusson-Carpenter terminology), a warm phase with the second half. Maximum cooling is 1 year prior to maximum warming in both oceans. In the Atlantic the cold phase occurs most consistently; in the Indian Ocean the warm phase occurs most consistently. There is a season-by-season reversal of SST anomalies and, to a lesser extent, pressure anomalies between the cold and warm phases. This is the basis for the biennial component of the ENSO signal.Our results indicate that the ENSO signal in African rainfall variability is a manifestation of ENSO's influence on SSTs in the Atlantic and Indian Oceans and, in turn, their influence on rainfall. The cold and warm phases correspond roughly to enhanced and reduced rainfall over the African continent, respectively. A similar reversal of rainfall anomalies is apparent season-by-season during these phases. The timing of the warming and cooling is relatively constant in the Indian Ocean. However, the onset of the warming and cooling in the south and equatorial Atlantic occurs progressively later from south to north, thus the signal propagates northward

  18. Intraseasonal sea surface warming in the western Indian Ocean by oceanic equatorial Rossby waves

    DTIC Science & Technology

    2017-05-09

    an equatorial westward jet of 80 cm s1 associated with downwelling ER waves. When anomalous currents associated with ER waves are removed in the...Oceans in association with the Madden-Julian Oscillation (MJO) [Madden and Julian, 1972; Drushka et al., 2012; Halkides et al., 2015]. Similarly...intraseasonal sea surface temperature (SST) variations of 0.6°C are associated with the MJO, neglect- ing diurnal temperature variations that can exceed 2.0°C

  19. Antimony and arsenic biogeochemistry in the western Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Cutter, Gregory A.; Cutter, Lynda S.; Featherstone, Alison M.; Lohrenz, Steven E.

    The subtropical to equatorial Atlantic Ocean provides a unique regime in which one can examine the biogeochemical cycles of antimony and arsenic. In particular, this region is strongly affected by inputs from the Amazon River and dust from North Africa at the surface, and horizontal transport at depth from high-latitude northern (e.g., North Atlantic Deep Water) and southern waters (e.g., Antarctic Bottom and Intermediate Waters). As a part of the 1996 Intergovernmental Oceanographic Commission's Contaminant Baseline Survey, data for dissolved As(III+V), As(III), mono- and dimethyl arsenic, Sb(III+V), Sb(III), and monomethyl antimony were obtained at six vertical profile stations and 44 sites along the 11,000 km transect from Montevideo, Uruguay, to Bridgetown, Barbados. The arsenic results were similar to those in other oceans, with moderate surface depletion, deep-water enrichment, a predominance of arsenate (>85% As(V)), and methylated arsenic species and As(III) in surface waters that are likely a result of phytoplankton conversions to mitigate arsenate "stress" (toxicity). Perhaps the most significant discovery in the arsenic results was the extremely low concentrations in the Amazon Plume (as low as 9.8 nmol/l) that appear to extend for considerable distances offshore in the equatorial region. The very low concentration of inorganic arsenic in the Amazon River (2.8 nmol/l; about half those in most rivers) is probably the result of intense iron oxyhydroxide scavenging. Dissolved antimony was also primarily in the pentavalent state (>95% antimonate), but Sb(III) and monomethyl antimony were only detected in surface waters and displayed no correlations with biotic tracers such as nutrients and chlorophyll a. Unlike As(III+V)'s nutrient-type vertical profiles, Sb(III+V) displayed surface maxima and decreased into the deep waters, exhibiting the behavior of a scavenged element with a strong atmospheric input. While surface water Sb had a slight correlation with

  20. Ocean Color and the Equatorial Annual Cycle in the Pacific

    NASA Astrophysics Data System (ADS)

    Hammann, A. C.; Gnanadesikan, A.

    2012-12-01

    The presence of chlorophyll, colored dissolved organic matter (CDOM) and other scatterers in ocean surface waters affect the flux divergence of solar radiation and thus the vertical distribution of radiant heating of the ocean. While this may directly alter the local mixed-layer depth and temperature (Martin 1985; Strutton & Chavez 2004), non-local changes are propagated through advection (Manizza et al. 2005; Murtugudde et al. 2002; Nakamoto et al. 2001; Sweeny et al. 2005). In and coupled feedbacks (Lengaigne et al. 2007; Marzeion & Timmermann 2005). Anderson et al. (2007), Anderson et al. (2009) and Gnanadesikan & Anderson (2009) have performed a series of experiments with a fully coupled climate model which parameterizes the e-folding depth of solar irradiance in terms of surface chlorophyll-a concentration. The results have so far been discussed with respect to the climatic mean state and ENSO variability in the tropical Pacific. We extend the discussion here to the Pacific equatorial annual cycle. The focus of the coupled experiments has been the sensitivity of the coupled system to regional differences in chlorophyll concentration. While runs have been completed with realistic SeaWiFS-derived monthly composite chlorophyll ('green') and with a globally chlorophyll-free ocean ('blue'), the concentrations in two additional runs have been selectively set to zero in specific regions: the oligotrophic subtropical gyres ('gyre') in one case and the mesotrophic gyre margins ('margin') in the other. The annual cycle of ocean temperatures exhibits distinctly reduced amplitudes in the 'blue' and 'margin' experiments, and a slight reduction in 'gyre' (while ENSO variability almost vanishes in 'blue' and 'gyre', but amplifies in 'margin' - thus the frequently quoted inverse correlation between ENSO and annual amplitudes holds only for the 'green' / 'margin' comparison). It is well-known that on annual time scales, the anomalous divergence of surface currents and vertical

  1. Mn/Ca and Fe/Ca data from multiple species of planktonic foraminifers from the equatorial Pacific and subtropical South Atlantic: Indicators of surface ocean productivity, diagenesis of the shells, or both?

    NASA Astrophysics Data System (ADS)

    Howlett, J.; Mekik, F.

    2015-12-01

    Mn/Ca ratios in planktonic foraminifers have been purported to be indicators of terrestrial input, marine oxidation-reduction reactions and sea surface productivity in the eastern tropical Pacific. We investigated this hypothesis using Mn/Ca and Fe/Ca data from five species of planktonic foraminifers in 32 core tops from the eastern equatorial Pacific (EEP), five species from 12 core tops in the western equatorial Pacific, and two species from 15 core tops on the Rio Grande Rise. We present Mn/Ca and Fe/Ca data from Neogloboquadrina dutertrei, Globorotalia menardii, Globigerina bulloides, Pulleniatina obliquiloculata and Globorotalia tumida from the eastern and western equatorial Pacific and from Globorotalia truncatulinoides and Globorotalia inflata on the Rio Grande Rise. We find that the environmental parameter depicted by Mn/Ca and Fe/Ca ratios depends on the species of foraminifer from which the data was derived. Fe/Ca from N. dutertrei in the EEP have statistically significant and quantifiable relationships with apparent oxygen utilization, dissolved phosphate concentration and dissolved oxygen concentration in the habitat depths of this species. The Mn/Ca ratio from P. obliquiloculata and G. tumida are highest in regions of greatest productivity in the EEP. On the Rio Grande Rise, we explored the effect of dissolution in the sediments on Mn/Ca and Fe/Ca ratios from planktonic foraminifers. We used the G. menardii fragmentation index as our sedimentary dissolution indicator, and found that dissolution does not have a strong effect on the Mn/Ca and Fe/Ca ratios measured from foraminifers tests.

  2. Importance of the Equatorial Undercurrent on the sea surface salinity in the eastern equatorial Atlantic in boreal spring

    NASA Astrophysics Data System (ADS)

    Da-Allada, C. Y.; Jouanno, J.; Gaillard, F.; Kolodziejczyk, N.; Maes, C.; Reul, N.; Bourlès, B.

    2017-01-01

    The physical processes implied in the sea surface salinity (SSS) increase in the equatorial Atlantic Cold Tongue (ACT) region during boreal spring and the lag observed between boreal spring SSS maximum and sea surface temperature (SST) summer minimum are examined using mixed-layer salinity budgets computed from observations and model during the period 2010-2012. The boreal spring SSS maximum is mainly explained by an upward flux of high salinity originating from the core of the Equatorial Undercurrent (EUC) through vertical mixing and advection. The vertical mixing contribution to the mixed-layer salt budget peaks in April-May. It is controlled primarily by (i) an increased zonal shear between the surface South Equatorial Current and the subsurface EUC and (ii) the presence of a strong salinity stratification at the mixed-layer base from December to May. This haline stratification that is due to both high precipitations below the Inter Tropical Convergence Zone and zonal advection of low-salinity water from the Gulf of Guinea explains largely the seasonal cycle of the vertical advection contribution to the mixed-layer salt budget. In the ACT region, the SST reaches its maximum in March/April and minimum in July/August. This SST minimum appears 1 month after the maximum of SSS. The 1 month lag observed between the maximum of SSS in June and the minimum of SST in July is explained by the shallowing of the EUC salinity core in June, then the weakening/erosion of the EUC in June-July which dramatically reduces the lateral subsurface supply of high-saline waters.

  3. 77 FR 22523 - Safety Zone; 2012 Ocean City Air Show; Atlantic Ocean, Ocean City, MD

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-16

    ... action is necessary to provide for the safety of life on navigable waters during the 2012 Ocean City Air... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; 2012 Ocean City Air Show; Atlantic Ocean, Ocean City, MD AGENCY: Coast Guard, DHS. ACTION: Notice of proposed rulemaking. SUMMARY: The Coast...

  4. Annual and semi-annual cycle of equatorial Atlantic circulation associated with basin mode resonance

    NASA Astrophysics Data System (ADS)

    Brandt, Peter; Claus, Martin; Greatbatch, Richard J.; Kopte, Robert; Toole, John M.; Johns, William E.; Böning, Claus W.

    2016-04-01

    Seasonal variability of the tropical Atlantic circulation is dominated by the annual cycle, but semi-annual variability is also pronounced, despite weak forcing at that period. Here we use multi-year, full depth velocity measurements from the central equatorial Atlantic to analyze the vertical structure of annual and semi-annual variations of zonal velocity. A baroclinic modal decomposition finds that the annual cycle is dominated by the 4th mode and the semi-annual cycle by the 2nd mode. Similar local behavior is found in a high-resolution general circulation model. This simulation reveals that the annual and semi-annual cycles of the respective dominant baroclinic modes are associated with characteristic basin-wide structures. Using an idealized linear reduced-gravity model to simulate the dynamics of individual baroclinic modes, it is shown that the observed circulation variability can be best explained by resonant equatorial basin modes. Companion simulations using the reduced-gravity model varying the basin geometry, i.e. square basin versus realistic coastlines, and forcing, i.e. spatially uniform versus spatially varying wind forcing, show a structural robustness of the simulated basin modes. A main focus of this study is the seasonal variability of the Equatorial Undercurrent (EUC) as identified in recent observational studies. Main characteristics of the observed EUC including seasonal variability of transport, core depth, and maximum core velocity can be explained by the linear superposition of the dominant equatorial basin modes as obtained from the reduced-gravity model.

  5. 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.

  6. NOAA Research Vessel Explores Atlantic Ocean Seamounts

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2014-10-01

    Mike Ford, a biological oceanographer with the National Oceanic and Atmospheric Administration (NOAA), sat rapt in front of a bank of high-definition monitors. They provided live video and data feeds from a tethered pair of instrument-laden remotely operated vehicles (ROVs) that were descending 4692 meters on their deepest dive ever. Their target: an unnamed and unexplored New England seamount discovered in the North Atlantic last year.

  7. 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.

  8. Organic-walled dinoflagellate cysts in western equatorial Atlantic surface sediments: distributions and their relation to environment.

    PubMed

    Vink; Zonneveld; Willems

    2000-11-01

    In contrast to the wide range of studies carried out in temperate and high-latitude oceanic regions, only a few studies have focused on recent and Holocene organic-walled dinoflagellate cyst assemblages from the tropics. This information is, however, essential for fully understanding the ability of species to adapt to different oceanographic regimes, and ultimately their potential application to local and regional palaeoenvironmental and palaeoceanographic reconstructions. Surface sediment samples of the western equatorial Atlantic Ocean north of Brazil, an area greatly influenced by Amazon River discharge waters, were therefore analysed in detail for their organic-walled dinoflagellate cyst content. A diverse association of 43 taxa was identified, and large differences in cyst distribution were observed. The cyst thanatocoenosis in bottom sediments reflects the seasonal advection of Amazon River discharge water through the Guyana Current and the North Equatorial Countercurrent well into the North Atlantic. To establish potential links between cyst distribution and the environmental conditions of the upper water column, distribution patterns were compared with mean temperature, salinity, density and stratification gradients within the upper water column (0-100m) over different times of the year, using correspondence analysis and canonical correspondence analysis. The analyses show that differences in these parameters only play a subordinate role in determining species distribution. Instead, nutrient availability, or related factors, dominates the distribution pattern. The only possible indicators of slightly reduced salinities are Trinovantedinium applanatum and Lingulodinium machaerophorum. Four assemblage groups of cyst taxa with similar environmental affinities related to specific water masses/currents can be distinguished and have potential for palaeoenvironmental reconstruction.

  9. Air-sea interactions and oceanic processes in the development of different Atlantic Niño patterns

    NASA Astrophysics Data System (ADS)

    Martin-Rey, Marta; Polo, Irene; Rodríguez-Fonseca, Belén; Lazar, Alban

    2016-04-01

    Atlantic Niño is the leading mode of inter-annual variability of the tropical Atlantic basin at inter-annual time scales. A recent study has put forward that two different Atlantic Niño patterns co-exist in the tropical Atlantic basin during negative phases of the Atlantic Multidecadal Oscillation. The leading mode, Basin-Wide (BW) Atlantic Niño is characterized by an anomalous warming extended along the whole tropical basin. The second mode, the Dipolar (D) Atlantic Niño presents positive Sea Surface Temperature (SST) anomalies in the central-eastern equatorial band, surrounded by negative ones in the North and South tropical Atlantic. The BW Atlantic Niño is associated with a weakening of both Azores and Sta Helena High, which reduces the tropical trades during previous autumn-winter. On the other hand, the D-Atlantic Niño is related to a strengthening of the Azores and a weakening of Helena High given rise to a meridional Sea Level Pressure (SLP) gradient that originates an intensification of the subtropical trades and anomalous westerlies along the equatorial band. This different wind forcing suggests that different oceanic processes could act in the development of the BW and D Atlantic Niño patterns. For this reason, an inter-annual simulation with the ocean NEMO model has been performed and the heat budget analysis has been analysed for each Atlantic Niño mode. The results suggest that the two Atlantic Nino configurations have different timing. The heat budget analysis reveals that BW Atlantic Nino SST pattern is due to anomalous air-sea heat fluxes in the south tropical and western equatorial Atlantic during the autumn-winter, while vertical processes are responsible of the warming in the central and eastern part of the basin during late-winter and spring. For the D-Atlantic Nino, the subtropical cooling is attributed to turbulent heat fluxes, the equatorial SST signal is mainly forced by vertical entrainment. The role of the oceanic waves in the

  10. Annual cycle of equatorial East-West circulation over the Indian and Pacific oceans

    SciTech Connect

    Murakami, T.; Wang, B. )

    1993-05-01

    Along the equator, the easterlies are strongest above the convective center over the maritime continent, while westerlies reach their maximum just above the dry zone over the equatorial Pacific. This is different from what is anticipated. The present study provides evidence that the midlatitude-equatorial coupling is primarily responsible for the maintenance of the annual mean total 200-mb zonal winds along the equator, whereas convection contributes a great deal to the annual mean upper-level equatorial divergent winds. Annual cycles occurring over the extratropics act as a transient eddy forcing of the equatorial annual mean 200-mb zonal wind through three-dimensional convergence of localized Eliassen-Palm (E-P) fluxes and accelerate the 200-mb annual mean westerlies (easterlies) over the equatorial Indian Ocean where E-P fluxes are horizontally divergent (convergent). The baroclinic contribution appears to be minimal. The annual cycles differ remarkably between the equatorial Indian and eastern Pacific oceans. The annual cycle in the equatorial Indian Ocean is characterized by (1) the eastward phase propagation of monthly mean anomaly zonal winds with an inverse relationship between the surface and 200 mb and (2) the highest SST occurring about three (four) months prior to the strongest surface westerlies. The annual cycle in the equatorial eastern Pacific exhibits coherent westward propagation of monthly mean anomaly SST and surface zonal winds, indicating the importance of planetary boundary-layer processes. The equatorial convection apparently contributes little to the annual cycle of the upper-level east-west equatorial circulation. The annual cycle in the upper-level zonal winds over the equatorial eastern Pacific is largely controlled by a pronounced annual cycle of the 200-mb zonal wind occurring in the extratropics of each hemisphere. 45 refs., 9 figs.

  11. Ocean dynamics, not dust, have controlled equatorial Pacific productivity over the past 500,000 years.

    PubMed

    Winckler, Gisela; Anderson, Robert F; Jaccard, Samuel L; Marcantonio, Franco

    2016-05-31

    Biological productivity in the equatorial Pacific is relatively high compared with other low-latitude regimes, especially east of the dateline, where divergence driven by the trade winds brings nutrient-rich waters of the Equatorial Undercurrent to the surface. The equatorial Pacific is one of the three principal high-nutrient low-chlorophyll ocean regimes where biological utilization of nitrate and phosphate is limited, in part, by the availability of iron. Throughout most of the equatorial Pacific, upwelling of water from the Equatorial Undercurrent supplies far more dissolved iron than is delivered by dust, by as much as two orders of magnitude. Nevertheless, recent studies have inferred that the greater supply of dust during ice ages stimulated greater utilization of nutrients within the region of upwelling on the equator, thereby contributing to the sequestration of carbon in the ocean interior. Here we present proxy records for dust and for biological productivity over the past 500 ky at three sites spanning the breadth of the equatorial Pacific Ocean to test the dust fertilization hypothesis. Dust supply peaked under glacial conditions, consistent with previous studies, whereas proxies of export production exhibit maxima during ice age terminations. Temporal decoupling between dust supply and biological productivity indicates that other factors, likely involving ocean dynamics, played a greater role than dust in regulating equatorial Pacific productivity.

  12. Ocean dynamics, not dust, have controlled equatorial Pacific productivity over the past 500,000 years

    NASA Astrophysics Data System (ADS)

    Winckler, Gisela; Anderson, Robert F.; Jaccard, Samuel L.; Marcantonio, Franco

    2016-05-01

    Biological productivity in the equatorial Pacific is relatively high compared with other low-latitude regimes, especially east of the dateline, where divergence driven by the trade winds brings nutrient-rich waters of the Equatorial Undercurrent to the surface. The equatorial Pacific is one of the three principal high-nutrient low-chlorophyll ocean regimes where biological utilization of nitrate and phosphate is limited, in part, by the availability of iron. Throughout most of the equatorial Pacific, upwelling of water from the Equatorial Undercurrent supplies far more dissolved iron than is delivered by dust, by as much as two orders of magnitude. Nevertheless, recent studies have inferred that the greater supply of dust during ice ages stimulated greater utilization of nutrients within the region of upwelling on the equator, thereby contributing to the sequestration of carbon in the ocean interior. Here we present proxy records for dust and for biological productivity over the past 500 ky at three sites spanning the breadth of the equatorial Pacific Ocean to test the dust fertilization hypothesis. Dust supply peaked under glacial conditions, consistent with previous studies, whereas proxies of export production exhibit maxima during ice age terminations. Temporal decoupling between dust supply and biological productivity indicates that other factors, likely involving ocean dynamics, played a greater role than dust in regulating equatorial Pacific productivity.

  13. Ocean dynamics, not dust, have controlled equatorial Pacific productivity over the past 500,000 years

    PubMed Central

    Winckler, Gisela; Anderson, Robert F.; Jaccard, Samuel L.; Marcantonio, Franco

    2016-01-01

    Biological productivity in the equatorial Pacific is relatively high compared with other low-latitude regimes, especially east of the dateline, where divergence driven by the trade winds brings nutrient-rich waters of the Equatorial Undercurrent to the surface. The equatorial Pacific is one of the three principal high-nutrient low-chlorophyll ocean regimes where biological utilization of nitrate and phosphate is limited, in part, by the availability of iron. Throughout most of the equatorial Pacific, upwelling of water from the Equatorial Undercurrent supplies far more dissolved iron than is delivered by dust, by as much as two orders of magnitude. Nevertheless, recent studies have inferred that the greater supply of dust during ice ages stimulated greater utilization of nutrients within the region of upwelling on the equator, thereby contributing to the sequestration of carbon in the ocean interior. Here we present proxy records for dust and for biological productivity over the past 500 ky at three sites spanning the breadth of the equatorial Pacific Ocean to test the dust fertilization hypothesis. Dust supply peaked under glacial conditions, consistent with previous studies, whereas proxies of export production exhibit maxima during ice age terminations. Temporal decoupling between dust supply and biological productivity indicates that other factors, likely involving ocean dynamics, played a greater role than dust in regulating equatorial Pacific productivity. PMID:27185933

  14. Insolation cycles as a major control of equatorial indian ocean primary production

    PubMed

    Beaufort; Lancelot; Camberlin; Cayre; Vincent; Bassinot; Labeyrie

    1997-11-21

    Analysis of a continuous sedimentary record taken in the Maldives indicates that strong primary production fluctuations (70 to 390 grams of carbon per square meter per year) have occurred in the equatorial Indian Ocean during the past 910,000 years. The record of primary production is coherent and in phase with the February equatorial insolation, whereas it shows diverse phase behavior with delta18O, depending on the orbital frequency (eccentricity, obliquity, or precession) examined. These observations imply a direct control of productivity in the equatorial oceanic system by insolation. In the equatorial Indian Ocean, productivity is driven by the wind intensity of westerlies, which is related to the Southern Oscillation; therefore, it is suggested that a precession forcing on the Southern Oscillation is responsible for the observed paleoproductivity dynamics.

  15. Metal quotas of plankton in the equatorial Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Twining, Benjamin S.; Baines, Stephen B.; Bozard, James B.; Vogt, Stefan; Walker, Elyse A.; Nelson, David M.

    2011-03-01

    The micronutrient metals Mn, Fe, Co, Ni and Zn are required for phytoplankton growth, and their availability influences ocean productivity and biogeochemistry. Here we report the first direct measurements of these metals in phytoplankton and protozoa from the equatorial Pacific Ocean. Cells representing 4 functional groups (diatoms, autotrophic flagellates, heterotrophic flagellates and autotrophic picoplankton) were collected from the surface mixed layer using trace-metal clean techniques during transects across the equator at 110°W and along the equator between 110°W and 140°W. Metal quotas were determined for individual cells with synchrotron x-ray fluorescence microscopy, and cellular stoichiometries were calculated relative to measured P and S, as well as to C calculated from biovolume. Bulk particulate (>3 μm) metal concentrations were also determined at 3 stations using inductively coupled plasma mass spectrometry for comparison to single-cell stoichiometries. Phosphorus-normalized Mn, Fe, Ni and Zn ratios were significantly higher in diatoms than other cell types, while Co stoichiometries were highest in autotrophic flagellates. The magnitude of these effects ranged from approximately 2-fold for Mn in diatoms and autotrophic flagellates to nearly an order of magnitude for Fe in diatoms and picoplankton. Variations in S-normalized metal stoichiometries were also significant but of lower magnitude (1.4 to 6-fold). Cobalt and Mn quotas were 1.6 and 3-fold higher in autotrophic than heterotrophic flagellates. Autotrophic picoplankton were relatively enriched in Ni but depleted in Zn, matching expectations based on known uses of these metals in prokaryotes and eukaryotes. Significant spatial variability in metal stoichiometries was also observed. At two stations deviations in Fe stoichiometries reflected features in the dissolved Fe distribution. At these same stations, high Ni stoichiometries in autotrophic flagellates were correlated with elevated ammonium

  16. Late quaternary paleoceanography of the Atlantic Ocean: foraminiferal faunal and stable-isotopic evidence

    SciTech Connect

    Mix, A.C.

    1986-01-01

    The timing, frequencies, and rates of change of tropical Atlantic climates are studied on a glacial/interglacial scale, using foraminferal faunal abundance and stable isotopic data to estimate temperatures, ice volumes, and water mass properties of the surface and deep ocean. Oxygen-isotope and radiocarbon data constrain the timing of the last deglacial transition (Termination 1) to between 14,000 and 6000 yr BP. Deglaciation was not a continuous process, but may have occurred in steps from 14,000 to 12,000 yr BP, 10,000 to 8000 yr BP, and 7000 to 6000 yr BP. Changes in the ..delta../sup 18/O of glacier ice may induce a lag of the marine ..delta../sup 18/O record behind ice volume of 1000 to 3000 years. Temperature changes estimated by foraminferal transfer functions were not detected in down-core planktonic foraminferal ..delta../sup 18/O data. Hemispheric symmetry of glacial cooling may reflect linkage to high latitude climate changes via trade wind intensities and/or directions. During deglaciation, the North Atlantic was relatively cold, the South Atlantic was relatively warm, and equatorial seasonal contrast was low. This may reflect reduction of northward cross-equatorial heat transport in the ocean, and possible monsoonal effects. Climate changes also extend to the deep ocean. At mid-depths of the tropical Atlantic, minimum Atlantic-Pacific ..delta../sup 13/C difference occurring on average during deglaciation (with a strong 23,000-yr precession cycle) suggests reduced formation of a warm component of NADW during deglaciation. A deeper sites in the North Atlantic, reduced ventilation of deep basins during glacial maxima is linked to surface-water variability of the subpolar North Atlantic.

  17. Dissipation effects in North Atlantic Ocean modeling

    NASA Astrophysics Data System (ADS)

    Dietrich, D. E.; Mehra, A.; Haney, R. L.; Bowman, M. J.; Tseng, Y. H.

    2004-03-01

    Numerical experiments varying lateral viscosity and diffusivity between 20 and 150 m2/s in a North Atlantic Ocean (NAO) model having 4th-order accurate numerics, in which the dense deep current system (DCS) from the northern seas and Arctic Ocean is simulated directly show that Gulf Stream (GS) separation is strongly affected by the dissipation of the DCS. This is true even though the separation is highly inertial with large Reynolds number for GS separation flow scales. We show that realistic NAO modeling requires less than 150 m2/s viscosity and diffusivity in order to maintain the DCS material current with enough intensity to get realistic GS separation near Cape Hatteras (CH). This also demands accurate, low dissipation numerics, because of the long transit time (1-10 years) of DCS material from its northern seas and Arctic Ocean source regions to the Cape Hatteras region and the small lateral and vertical scales of DCS.

  18. Interannual variability of zonal currents in the equatorial Indian Ocean: respective control of IOD and ENSO

    NASA Astrophysics Data System (ADS)

    Sachidanandan, Chinnu; Lengaigne, Matthieu; Muraleedharan, Pillathu Moolayil; Mathew, Basil

    2017-07-01

    The observational record is too short to confidently differentiate the relative contributions of Indian Ocean Dipole (IOD) and El Niño-Southern Oscillation (ENSO) on the interannual variability of the equatorial current system in the Indian Ocean because of the strong tendency of these two modes to co-occur. In this study, we analyse a five-decade simulation from an ocean general circulation model forced to describe the main interannual variations of surface and subsurface equatorial zonal currents in the Indian Ocean. This simulation is first shown to accurately capture the surface and subsurface zonal current variations in the equatorial region derived from the available observations. Through an EOF analysis on the model outputs, our results further reveals two main modes of equatorial current interannual variability: a dominant mode with largest amplitude in fall largely describing the variability of the fall Wyrtki jet intensity followed a few months later by a secondary mode maximum in winter largely describing the interannual variability of the subsurface currents in that season. Our analysis further confirms that the IOD is largely responsible for the interannual modulation of fall Wyrtki jet intensity by modulating the equatorial wind intensity during that season. The IOD is also responsible for strong subsurface current variations until December, induced by the delayed effect of the IOD wind signal onto the equatorial thermocline tilt. The equatorial current system response to ENSO is weaker and delayed compared to that of the IOD. The remote and delayed impact of ENSO in the IO indeed induces equatorial wind variations in winter that modulate the winter surface current intensity and the spring equatorial undercurrent intensity through its delayed impact on the thermocline tilt.

  19. Sensitivity of the Oceanic Turbulent Boundary Layer to Cyclic Insolation Change with Response Periods of 23 to 2.5 Ky: an Equatorial Atlantic Record for the Last 200 Ka

    NASA Technical Reports Server (NTRS)

    Mcintyre, Andrew

    1990-01-01

    Time series of sea-surface temperature in cores sited beneath the region of maximum divergence centered on 10 degrees W are characterized by two sets of periodic signals. The dominant signal is centered on a period of 23 Ky and is coherent with and lags, approx. 2.5 Ky, the precessional component of orbitally controlled insolation. The subdominant periods occur between 4.0 and 2.5 Ky. Both sets of signals record variation in the seasonal intensity of oceanic divergence modulated by variation in tropical easterly intensity. The longer periods are a response to precessional forcing. The forcing responsible for the shorter periods is unknown.

  20. High connectivity across the fragmented chemosynthetic ecosystems of the deep Atlantic Equatorial Belt: efficient dispersal mechanisms or questionable endemism?

    PubMed

    Teixeira, Sara; Olu, Karine; Decker, Carole; Cunha, Regina L; Fuchs, Sandra; Hourdez, Stéphane; Serrão, Ester A; Arnaud-Haond, Sophie

    2013-09-01

    Chemosynthetic ecosystems are distributed worldwide in fragmented habitats harbouring seemingly highly specialized communities. Yet, shared taxa have been reported from highly distant chemosynthetic communities. These habitats are distributed in distinct biogeographical regions, one of these being the so-called Atlantic Equatorial Belt (AEB). Here, we combined genetic data (COI) from several taxa to assess the possible existence of cryptic or synonymous species and to detect the possible occurrence of contemporary gene flow among populations of chemosynthetic species located on both sides of the Atlantic. Several Evolutionary Significant Units (ESUs) of Alvinocarididae shrimp and Vesicomyidae bivalves were found to be shared across seeps of the AEB. Some were also common to hydrothermal vent communities of the Mid-Atlantic Ridge (MAR), encompassing taxa morphologically described as distinct species or even genera. The hypothesis of current or very recent large-scale gene flow among seeps and vents was supported by microsatellite analysis of the shrimp species Alvinocaris muricola/Alvinocaris markensis across the AEB and MAR. Two nonmutually exclusive hypotheses may explain these findings. The dispersion of larvae or adults following strong deep-sea currents, possibly combined with biochemical cues influencing the duration of larval development and timing of metamorphosis, may result in large-scale effective migration among distant spots scattered on the oceanic seafloor. Alternatively, these results may arise from the prevailing lack of knowledge on the ocean seabed, apart from emblematic ecosystems (chemosynthetic ecosystems, coral reefs or seamounts), where the widespread classification of endemism associated with many chemosynthetic taxa might hide wider distributions in overlooked parts of the deep sea. © 2013 John Wiley & Sons Ltd.

  1. Revisiting the cause of the eastern equatorial Atlantic cold event in 2009

    NASA Astrophysics Data System (ADS)

    Burmeister, Kristin; Brandt, Peter; Lübbecke, Joke F.

    2016-07-01

    An extreme cold sea surface temperature event occurred in the Atlantic cold tongue region in boreal summer 2009. It was preceded by a strong negative Atlantic meridional mode event associated with north-westerly wind anomalies along the equator from March to May. Although classical equatorial wave dynamics suggest that westerly wind anomalies should be followed by a warming in the eastern equatorial Atlantic, an abrupt cooling took place. In the literature two mechanisms—meridional advection of subsurface temperature anomalies and planetary wave reflection—are discussed as potential causes of such an event. Here, for the first time we use in situ measurements in addition to satellite and reanalysis products to investigate the contribution of both mechanisms to the 2009 cold event. Our results suggest that meridional advection is less important in cold events than in corresponding warm events, and, in particular, did not cause the 2009 cold event. Argo float data confirm previous findings that planetary wave reflection contributed to the onset of the 2009 cold event. Additionally, our analysis suggests that higher baroclinic modes were involved.

  2. 33 CFR 165.T05-0494 - Safety Zone, Atlantic Ocean; Ocean City, NJ.

    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; Ocean City, NJ. 165.T05-0494 Section 165.T05-0494 Navigation and Navigable Waters COAST GUARD... § 165.T05-0494 Safety Zone, Atlantic Ocean; Ocean City, NJ. (a) Location. The following area is a safety...

  3. 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

  4. 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.

  5. Oceanic Origin of Tropical Atlantic SST Biases

    NASA Astrophysics Data System (ADS)

    Chang, P.; Xu, Z.; Li, M.; Patricola, C. M.

    2012-12-01

    Most coupled general circulation models (CGCMs) suffer from a prominent warm sea surface temperature (SST) bias in the southeastern tropical Atlantic Ocean off the coast of Africa. The origin of the bias is not understood and remains highly controversial. Previous studies suggest that the origin of the bias stems from systematic errors of atmospheric models in simulating surface heat flux and coastal wind, or poorly simulated coastal upwelling. In this study, we show, using different reanalysis and observational data sets combined with a set of eddy-resolving regional ocean model simulations, that systematic errors in ocean models also make a significant contribution to the bias problem. In particular, (1) the strong warm bias at the Angola Benguela front that is maintained by the local wind and the convergence of Angola and Benguela Current is caused by an overshooting of the Angola Current in ocean models and (2) the alongshore warm bias to the south of the front is caused by ocean model deficiencies in simulating the sharp thermocline along the equator, the strong thermal gradient beneath the Angola current, and the complex circulation system within the Benguela upwelling zone.

  6. Convective Lofting Links Indian Ocean Air Pollution to Recurrent South Atlantic Ozone Maxima

    NASA Astrophysics Data System (ADS)

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

    2003-12-01

    We extend on our analysis of equatorial tropospheric ozone to illustrate the contributions of South Asian pollution export in forming episodes of high O3 over the Atlantic Ocean. We amplify on an earlier description of a broad resolution of the "Atlantic Paradox," for the Jan-Feb-March period, which included initial indications of a very long-distance contribution from South Asia. The approach has been to describe typical periods of significant maximum and minimum tropospheric ozone for early 1999, exploiting TOMS tropospheric ozone estimates jointly with characteristic features of the SHADOZ (Southern Hemisphere Additional Ozonesondes) ozone soundings. Further investigation of the Total Tropospheric Ozone (TTO) record for all of 1999 suggests that there are repeated periods of very long-distance Asian influence crossing Africa, with an apparent effect on those portions of the Atlantic Equatorial troposphere which are downwind. Trajectory analyses suggest that the pattern over the Indian Ocean is complex: a sequence invoving multiple or mixed combustion sources, low level transport, cumulonimbus venting, and high-level transport to the west seem to be indicated by the TTO record. Biomass burning, fossil and biofuel combustion, and lighting seem to all contribute. For the Atlantic, burning and lighting on adjacent continents as well as episodes of this cross-Africa long-distance transport are all linked in a coordinated seasonal march: all are related by movement of the sun. However, interseasonal tropical variability related to the Madden-Julian oscillation allows intermittent ozone buildups that depart from the seasonal norm.

  7. Phylogenetic identification of marine bacteria isolated from deep-sea sediments of the eastern South Atlantic Ocean.

    PubMed

    da Silva, Marcus Adonai Castro; Cavalett, Angélica; Spinner, Ananda; Rosa, Daniele Cristina; Jasper, Regina Beltrame; Quecine, Maria Carolina; Bonatelli, Maria Letícia; Pizzirani-Kleiner, Aline; Corção, Gertrudes; Lima, André Oliveira de Souza

    2013-12-01

    The deep-sea environments of the South Atlantic Ocean are less studied in comparison to the North Atlantic and Pacific Oceans. With the aim of identifying the deep-sea bacteria in this less known ocean, 70 strains were isolated from eight sediment samples (depth range between 1905 to 5560 m) collected in the eastern part of the South Atlantic, from the equatorial region to the Cape Abyssal Plain, using three different culture media. The strains were classified into three phylogenetic groups, Gammaproteobacteria, Firmicutes and Actinobacteria, by the analysis of 16s rRNA gene sequences. Gammaproteobacteria and Firmicutes were the most frequently identified groups, with Halomonas the most frequent genus among the strains. Microorganisms belonging to Firmicutes were the only ones observed in all samples. Sixteen of the 41 identified operational taxonomic units probably represent new species. The presence of potentially new species reinforces the need for new studies in the deep-sea environments of the South Atlantic.

  8. Impacts of Indonesian Throughflow on seasonal circulation in the equatorial Indian Ocean

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Yuan, Dongliang; Zhao, Xia

    2017-03-01

    Impacts of the Indonesian Throughflow (ITF) on seasonal circulation in the equatorial eastern Indian Ocean are investigated using the ocean-only model LICOM by opening and closing ITF passages. LICOM had daily forcing from NCEP reanalysis data during 2000-2011. It can reproduce vertical profiles of mean density and buoyancy frequency of World Ocean Atlas 2013 data. The model also simulates well annual oscillation in the central Indian Ocean and semiannual oscillation in the eastern Indian Ocean of sea level anomalies (SLA) using satellite altimeter data, as well as the semiannual oscillation of surface zonal equatorial currents of Ocean Surface Current Analyses Real Time current data in the equatorial Indian Ocean. The wave decomposition method is used to analyze the propagation and reflection of equatorial long waves based on LICOM output. Wave analysis suggests that ITF blockage mainly influences waves generated from the Indian Ocean but not the Pacific Ocean, and eastern boundary reflections play an important role in semiannual oscillations of SLA and zonal current differences in the equatorial Indian Ocean associated with ITF. Reconstructed ITF-caused SLA using wave decomposition coefficient differences between closed and open ITF-passage experiments suggest both Kelvin and Rossby waves from the first baroclinic mode have comparable contributions to the semiannual oscillations of SLA difference. However, reconstructed ITF-caused surface zonal currents at the equator suggest that the first meridional-mode Rossby wave has much greater contribution than the first baroclinic mode Kelvin wave. Both reconstructed sea level and zonal currents demonstrate that the first baroclinic mode has a greater contribution than other baroclinic modes.

  9. Hurricane Gonzalo in the Atlantic Ocean

    NASA Image and Video Library

    2017-09-28

    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

  10. Phytoplankton bloom in the North Atlantic Ocean

    NASA Image and Video Library

    2017-09-27

    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

  11. Impacts of Indonesian Throughflow on seasonal circulation in the equatorial Indian Ocean

    NASA Astrophysics Data System (ADS)

    Wang, Jing

    2017-04-01

    Impacts of the Indonesian Throughflow (ITF) on the seasonal circulation of the equatorial eastern Indian Ocean are investigated using the ocean-only model LICOM by opening and closing ITF passages. LICOM is forced by daily forcing from NCEP reanalysis data during 2000-2011. And LICOM is capable of reproducing the vertical profiles of mean density and buoyancy frequency of WOA09 data, and also perform annual oscillation in central Indian Ocean and semiannual oscillation in the eastern Indian Ocean of sea level anomalies (SLA) from satellite altimeter data, and semiannual oscillation of surface zonal equatorial currents of OSCAR current data in the whole Indian Ocean very well. The wave decomposition method is used to analyze the propagation and reflection of equatorial long waves based on the LICOM output. Wave analysis suggests that ITF blockage mainly influence the waves generated from the equatorial Indian Ocean not the Pacific Ocean, and eastern boundary reflections play an important role in semiannual oscillation of SLA and zonal current difference associated with ITF in the equatorial Indian Ocean. Reconstructed ITF-caused SLA using wave decomposition coefficients difference between closed and open ITF passages experiment suggest both the Kelvin wave and Rossby waves from the first baroclinic mode have comparable contribution to the semiannual oscillations of SLA difference. However, reconstructed ITF-caused surface zonal current at the equator suggest the first meridional mode Rossby wave has much larger contribution than the Kelvin wave of the first baroclinic mode. Both reconstructed sea level and zonal currents demonstrate that the first baroclinic mode has larger contribution than other baroclinic modes.

  12. On the relationship between east equatorial Atlantic SST and ISM through Eurasian wave

    NASA Astrophysics Data System (ADS)

    Yadav, Ramesh Kumar

    2017-01-01

    The dominant mode of July-August (JA) seasonal variability of Indian summer monsoon rainfall (ISMR) are obtained by performing empirical orthogonal function (EOF) analysis. The first dominant mode of ISMR and its relationships with the sea surface temperature (SST), pressure level wind and geopotential height (GPH) fields are examined using gridded datasets for the period 1979-2014. The principal component of the first leading mode (PC1) obtained in the EOF analysis of JA rainfall over Indian landmass is highly correlated with north-west and central India rainfall, and anti-correlated with east-equatorial Atlantic SST (EEASST). The positive EEASST anomaly intensifies the inter-tropical convergence zone over Atlantic and west equatorial Africa which generates stationary wave meridionally, as meridional transfer of energy is strong, as the influence of background jet-streams are minimal over North Africa and Europe. The anomalous positive and negative GPH are generated over sub-tropics and extra-tropics, respectively, due to the stationary wave. This increases the climatological background steep pressure gradient between sub-tropics and extra-tropics consisting of anomalous negative GPH field over north-west (NW) Europe and vice versa for negative EEASST anomaly. The anomalous positive GPH over NW Europe acts as center of action for the propagation of a Rossby wave train to NW India via Europe consisting of anomalous high over NW of India. This intensifies the Tibetan High westward which reinforces the outbreak of monsoon activities over central and NW India.

  13. Modeling Salinity Exchanges Between the Equatorial Indian Ocean and the Bay of Bengal

    DTIC Science & Technology

    2016-06-01

    Sandeep, and V. Pant. 2016. Modeling salinity exchanges between the equatorial Indian Ocean and the Bay of Bengal. Oceanography 29(2):92–101, http...Bay of Bengal, models ranging from a 1/12.5° global ocean model to a ¼° regional Indian Ocean model to a 2 km local high-resolution coupled model...are used to simulate salinity exchanges in the Indian Ocean . Global Hybrid Coordinate Ocean Model simulations show a surprisingly large persistent flow

  14. Forcing of recent decadal variability in the Equatorial and North Indian Ocean

    NASA Astrophysics Data System (ADS)

    Thompson, P. R.; Piecuch, C. G.; Merrifield, M. A.; McCreary, J. P.; Firing, E.

    2016-09-01

    Recent decadal sea surface height (SSH) variability across the Equatorial and North Indian Ocean (ENIO, north of 5°S) is spatially coherent and related to a reversal in basin-scale, upper-ocean-temperature trends. Analysis of ocean and forcing fields from a data-assimilating ocean synthesis (ECCOv4) suggests that two equally important mechanisms of wind-driven heat redistribution within the Indian Ocean account for a majority of the decadal variability. The first is the Cross-Equatorial Cell (CEC) forced by zonal wind stress curl at the equator. The wind stress curl variability relates to the strength and position of the Mascarene High, which is influenced by the phase of the Indian Ocean Subtropical Dipole. The second mechanism is deep (700 m) upwelling related to zonal wind stress at the equator that causes deep, cross-equatorial overturning due to the unique geometry of the basin. The CEC acts to cool the upper ocean throughout most of the first decade of satellite altimetry, while the deep upwelling delays and then amplifies the effect of the CEC on SSH. During the subsequent decade, reversals in the forcing anomalies drive warming of the upper ocean and increasing SSH, with the effect of the deep upwelling leading the CEC.

  15. A truncated oceanic spectral model for equatorial thermodynamic studies

    NASA Astrophysics Data System (ADS)

    Smith, Neville R.

    1988-12-01

    A β-plane model for equatorial circulation is transformed in terms of Hermite functions into a form where the meridional dependence is expressed in terms of spectral components. Linear analysis reveals a wave-dispersion relation similar in character to the regular model but with anti-Kelvin and anti-Yanai modes present. Depending upon the length scale used for the expansion, the evanescent frequency zone between the planetary and inertia-gravity modes, and between the two Yanai modes, may be changed. The truncated model offers an alternative view of the place of the primary wave modes in the overall scheme of equatorial planetary and gravity waves. The anti-Kelvin and anti-Yanai modes play an important role in returning the balance of the equatorial energy flux to the west at the eastern boundary. Transformation of the primitive equations into spectral form with low-order meridional wave number truncation yields a tractable, economical set of equations which have applications in the study of thermodynamic processes, parameterizations and for economical testing of numerical techniques. Second-order models are derived and they clearly expose the many couplings due to non-linear effects, diffusion, viscosity, pressure terms and the β effect.

  16. North Atlantic Finite Element Ocean Modeling

    NASA Astrophysics Data System (ADS)

    Veluthedathekuzhiyil, Praveen

    This thesis presents a modified version of the Finite Element Ocean Model (FEOM) developed at Alfred Wegener Institute for Polar and Marine Research (AWI) for the North Atlantic Ocean. A reasonable North Atlantic Ocean simulation is obtained against the observational data sets in a Control simulation (CS) where the surface boundary conditions are relaxed to a climatology. The vertical mixing in the model was tuned to represent convection in the model, also the horizontal mixing and diffusion coefficients to represent the changes in the resolution of the model’s unstructured grid. In addition, the open boundaries in the model are treated with a sponge layer where tracers are relaxed to climatology. The model is then further modified to accept the atmospheric flux forcing at the surface boundary with an added net heat flux correction and freshwater forcing from major rivers that are flowing into the North Atlantic Ocean. The impact of this boundary condition on the simulation results is then analyzed and shows many improvements albeit the drift in tracer properties around the Gulf Stream region remains as that of the CS case. However a comparison of the vertical sections at Cape Desolation and Cape Farewell with the available observational data sets shows many improvements in this simulation compared to that of the CS case. But the freshwater content in the Labrador Sea interior shows a continued drift as that of the CS case with an improvement towards the 10th model year. A detailed analysis of the boundary currents around the Labrador Sea shows the weak offshore transport of freshwater from the West Greenland Current (WGC) as one of the causes. To further improve the model and reasonably represent the boundary currents and associated sub-grid scale eddies in the model, a modified sub-grid scale parameterization based on Gent and McWilliams, (1990) is adopted. The sensitivity of using various approaches in the thickness diffusion parameter ( Kgm) for this

  17. 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

  18. Space Radar Image of North Atlantic Ocean

    NASA Technical Reports Server (NTRS)

    1994-01-01

    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

  19. Pervasive reactive melt migration through fast-spreading lower oceanic crust (Hess Deep, equatorial Pacific Ocean)

    NASA Astrophysics Data System (ADS)

    Lissenberg, C. Johan; MacLeod, Christopher J.; Howard, Kerry A.; Godard, Marguerite

    2013-01-01

    Mid-ocean ridge basalt (MORB) is the most abundant magma on Earth, and provides a geochemical window into the mantle. Deriving mantle composition and melting processes from the erupted lavas requires correction to be made for their evolution as they pass through and generate the oceanic crust. This is typically done by assuming that modification of melts in crustal magma chambers occurs exclusively by fractional crystallisation. However, extensive mineral major- and trace element data from a full section of fast-spread lower crustal rocks exposed in Hess Deep (equatorial Pacific Ocean) demonstrate that their evolution is instead controlled by reactive porous flow. These reactions lead to a strong enrichment in, and fractionation of, incompatible trace elements in the melt (as recorded by clinopyroxene compositions), leading to melt compositions far outside of the compositional realm of MORB both in terms of trace element abundances and ratios. The reactive signature increases in strength up section, peaking in varitextured gabbros interpreted to represent the fossilised axial melt lens, indicating that reactive porous flow occurred on the scale of the entire lower crust. The enrichment of the melt is coupled with a strong trace element depletion of plagioclase, olivine, and, to a lesser extent, clinopyroxene cores, suggesting that these phases represent the residues of the reactions from which trace elements have been removed. The dominant role of reactive porous flow, and the resulting deviations from fractional crystallisation predictions, suggest that the lower oceanic crust plays a much more complex and significant role in modifying the compositions of MORB than previously expected, with consequent implications for models of mantle processes.

  20. Southwest Atlantic Ocean Marathon Expedition, Leg 8.

    DTIC Science & Technology

    1986-07-01

    1150.1 2.649 2.770 84 37 27 407 82 778 27.400 7 9 12.210 78 6 1450.2 .2 1171.0 1160 0 2612 2.733 S4 379 27 413 2. 031 27 406 73, 12.214 79654. 1400.2 16.2...AD-R?2 192 SOUTHWEST ATLANTIC OCEAN MARATHON EXPEDITION LEG 9 (U) 1/5MASHINGTON UNIV SEATTLE DEPT OF OC ANOGRAPHY G 1 RODEN ET AL. JUL 86 NISSt4- 84 ...S 41 0.8 W AWS.0 1004.0 22.0o 240 16.1 15.6 30 OCT 84 8 37 40.3 S 41 0.6 W 5035.0 106.8 30.0 o350 17.0 13.8 ~ so OCT 84 9 38 0.4 S 42 0.5 W 5064.0

  1. The tectonic setting of the Seychelles, Mascarene and Amirante Plateaus in the Western Equatorial Indian Ocean

    NASA Technical Reports Server (NTRS)

    Mart, Y.

    1988-01-01

    A system of marine plateaus occurs in the western equatorial Indian Ocean, forming an arcuate series of wide and shallow banks with small islands in places. The oceanic basins that surround the Seychelles - Amirante region are of various ages and reflect a complex seafloor spreading pattern. The structural analysis of the Seychelle - Amirante - Mascarene region reflects the tectonic evolution of the western equatorial Indian Ocean. It is suggested that due to the seafloor spreading during a tectonic stage, the Seychelles continental block drifted southwestwards to collide with the oceanic crust of the Mascarene Basin, forming an elongated folded structure at first, and then a subduction zone. The morphological similarity, the lithological variability and the different origin of the Seychelles Bank, the Mascarene Plateau and the Amirante Arc emphasizes the significant convergent effects of various plate tectonic processes on the development of marine plateaus.

  2. The tectonic setting of the Seychelles, Mascarene and Amirante Plateaus in the Western Equatorial Indian Ocean

    NASA Technical Reports Server (NTRS)

    Mart, Y.

    1988-01-01

    A system of marine plateaus occurs in the western equatorial Indian Ocean, forming an arcuate series of wide and shallow banks with small islands in places. The oceanic basins that surround the Seychelles - Amirante region are of various ages and reflect a complex seafloor spreading pattern. The structural analysis of the Seychelle - Amirante - Mascarene region reflects the tectonic evolution of the western equatorial Indian Ocean. It is suggested that due to the seafloor spreading during a tectonic stage, the Seychelles continental block drifted southwestwards to collide with the oceanic crust of the Mascarene Basin, forming an elongated folded structure at first, and then a subduction zone. The morphological similarity, the lithological variability and the different origin of the Seychelles Bank, the Mascarene Plateau and the Amirante Arc emphasizes the significant convergent effects of various plate tectonic processes on the development of marine plateaus.

  3. Imprints of AMOC Perturbation in the Intermediate water of Equatorial Atlantic during the Last Interglacial Improved

    NASA Astrophysics Data System (ADS)

    Weldeab, S.

    2014-12-01

    Understanding of the last interglacial (LIG) is critical for the assessment of long-term impact of global warming on the Atlantic meridional overturning circulation (AMOC) and climate. Relative to the Millennium, air temperature over Greenland and eustatic sea-level during the LIG was higher by 8±4˚C and 4-8 m, with a considerable oscillation in the rate of meltwater input (NEEM Community rembers, Nature, v.493, p.489; Kopp et al., Nature, v. 462, p. 863) . The impact of millennial-scale LIG meltwater input on the AMOC and global climate is, however, less understood. Here we present a highly resolved, benthic foraminiferal multi-proxy record from the eastern equatorial Atlantic. The record shows that the LIG was punctuated by at least two episodes of reduced AMOC whose impact on the global climate varied considerably. While the event between 126,000 and 123,800 years ago lacks imprints on available global climate records, the AMOC perturbation between 129,000 and 128,000 years ago provides a causative link to a rapid increase of atmospheric CO2, peak air warming over Antarctica, and a slow down of the rate of global monsoon intensification. We suggest that the rate of meltwater input into the North Atlantic and the size of remanent Greenland ice sheet was critical in determining the degree of AMOC reduction and its effect on the interhemispheric climate.

  4. Sources of Fe to the Equatorial Pacific Ocean from the Holocene to Miocene

    NASA Astrophysics Data System (ADS)

    Ziegler, C. L.; Murray, R. W.; Plank, T.; Hemming, S. R.

    2007-12-01

    Biological productivity in the modern equatorial Pacific Ocean, a region with high nutrients and low chlorophyll, is currently limited by the micronutrient Fe. Whether this region was Fe limited in the past remains unclear. In order to test whether Fe was limiting in the past and to identify potential pathways of Fe delivery that could drive Fe fertilization (i.e., dust delivery from eolian inputs versus Fe supplied by the Equatorial Undercurrent), we chemically isolated the terrigenous material from marine sediment along a cross-equatorial meridional transect in the central equatorial Pacific at 140W and at Ocean Drilling Program Site 850 in the eastern equatorial Pacific. We quantified the contribution from each potential Fe-bearing terrigenous source using a complete suite of chemical- and isotopic discrimination strategies as well as multivariate statistical techniques. We find that the distribution of the terrigenous sources (i.e., Asian loess, South American ash, Papua New Guinea, and ocean island basalt) varies through time, latitude, and climate. Regardless of which method is used to determine accumulation rate, there also is no relationship between flux of any particular Fe source and climate. Moreover, there is no clear connection between a particular Fe source or pathway (eolian versus Undercurrent) to total productivity during the Last Glacial Maximum, Pleistocene glacial episodes, and the Miocene Biogenic Bloom. This would suggest an alternative process, such as an interoceanic reorganization of nutrient inventories, is responsible for past changes in carbon export in the open ocean, rather than simply Fe supply from dust and/or Equatorial Undercurrent processes.

  5. Sources of Fe to the equatorial Pacific Ocean from the Holocene to Miocene

    NASA Astrophysics Data System (ADS)

    Ziegler, Christa L.; Murray, Richard W.; Plank, Terry; Hemming, Sidney R.

    2008-06-01

    Biological productivity in the modern equatorial Pacific Ocean, a region with high nutrients and low chlorophyll, is currently limited by the micronutrient Fe. In order to test whether Fe was limiting in the past and to identify potential pathways of Fe delivery that could drive Fe fertilization (i.e., dust delivery from eolian inputs vs. Fe supplied by the Equatorial Undercurrent), we chemically isolated the terrigenous material from sediment along a cross-equatorial transect in the central equatorial Pacific at 140°W and at Ocean Drilling Program Site 850 in the eastern equatorial Pacific. We quantified the contribution from each potential Fe-bearing terrigenous source using a suite of chemical- and isotopic discrimination strategies as well as multivariate statistical techniques. We find that the distribution of the terrigenous sources (i.e., Asian loess, South American ash, Papua New Guinea, and ocean island basalt) varies through time, latitude, and climate. Regardless of which method is used to determine accumulation rate, there also is no relationship between flux of any particular Fe source and climate. Moreover, there is no connection between a particular Fe source or pathway (eolian vs. Undercurrent) to total productivity during the Last Glacial Maximum, Pleistocene glacial episodes, and the Miocene "Biogenic Bloom". This would suggest an alternative process, such as an interoceanic reorganization of nutrient inventories, may be responsible for past changes in total export in the open ocean, rather than simply Fe supply from dust and/or Equatorial Undercurrent processes. Additionally, perhaps a change in Fe source or flux is related to a change in a particular component of the total productivity (e.g., the production of organic matter, calcium carbonate, or biogenic opal).

  6. Plankton respiration in the Eastern Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Robinson, Carol; Serret, Pablo; Tilstone, Gavin; Teira, Eva; Zubkov, Mikhail V.; Rees, Andrew P.; Woodward, E. Malcolm S.

    2002-05-01

    Concurrent measurements of dark community respiration (DCR), gross production (GP), size fractionated primary production ( 14C PP), nitrogen uptake, nutrients, chlorophyll a concentration, and heterotrophic and autotrophic bacterial abundance were collected from the upper 200 m of a latitudinal (32°S-48°N) transect in the Eastern Atlantic Ocean during May/June 1998. The mean mixed layer respiration rate was 2.5±2.1 mmol O 2 m -3 d -1 ( n=119) for the whole transect, 2.2±1.1 mmol O 2 m -3 d -1 ( n=32) in areas where chlorophyll a was <0.5 mg m -3 and 1.5±0.7 mmol O 2 m -3 d -1 ( n=10) where chlorophyll a was <0.2 mg m -3. These values lie within the range of published data collected in comparable waters, they co-vary with indicators of heterotrophic and autotrophic biomass (heterotrophic bacterial abundance, chlorophyll a concentration, beam attenuation and particulate organic carbon concentration) and they can be reconciled with accepted estimates of total respiratory activity. The mean and median respiratory quotient (RQ), calculated as the ratio of dissolved inorganic carbon production to dissolved oxygen consumption, was 0.8 ( n=11). At the time of the study, plankton community respiration exceeded GP in the picoautotroph dominated oligotrophic regions (Eastern Tropical Atlantic [15.5°S-14.2°N] and North Atlantic Subtropical Gyre [21.5-42.5°N]), which amounted to 50% of the stations sampled along the 12,100 km transect. These regions also exhibited high heterotrophic: autotrophic biomass ratios, higher turnover rates of phytoplankton than of bacteria and low f ratios. However, the carbon supply mechanisms required to sustain the rates of respiration higher than GP could not be fully quantified. Future research should aim to determine the temporal balance of respiration and GP together with substrate supply mechanisms in these ocean regions.

  7. Eastern equatorial Pacific Ocean T-S variations with El Nino

    NASA Technical Reports Server (NTRS)

    Wang, O.; Fukumori, I.; Lee, T.; Johnson, G. C.

    2004-01-01

    Temperature-Salinity (T-S) relationship variability in the pycnocline of the eastern equatorial Pacific Ocean (NINO3 region, 5 degrees S ??degrees N, 150 degrees W ?? degrees W) over the last two decades is investigated using observational data and model simulation.

  8. Eastern equatorial Pacific Ocean T-S variations with El Nino

    NASA Technical Reports Server (NTRS)

    Wang, O.; Fukumori, I.; Lee, T.; Johnson, G. C.

    2004-01-01

    Temperature-Salinity (T-S) relationship variability in the pycnocline of the eastern equatorial Pacific Ocean (NINO3 region, 5 degrees S ??degrees N, 150 degrees W ?? degrees W) over the last two decades is investigated using observational data and model simulation.

  9. Thermodynamic Air/Ocean Feedback Mechanisms in the Equatorial Pacific

    DTIC Science & Technology

    1992-09-01

    statistical interpolation scheme, Monthly Weather Review, 109, 701-721, 1981. McCreary , Julian P. Jr., A model of tropical ocean-atmospheric interaction...Monthly Weather Review, 111, 370-387. McCreary , Julian P. Jr., and Anderson, David L. T., An overview of coupled ocean-atmosphere models of El Nino and...background section, but for now, it is sufficient to say that they are interchangeable. Numerous published theories (Wyrtki, 1975; McCreary , 1983

  10. A Tropical Ocean Recharge Mechanism for Climate Variability. Part I: Equatorial Heat Content Changes Induced by the Off-Equatorial Wind.

    NASA Astrophysics Data System (ADS)

    Wang, Xiaochun; Jin, Fei-Fei; Wang, Yuqing

    2003-11-01

    A reduced-gravity shallow-water model, an oceanic general circulation model for the Pacific region, and the analytical model of the equatorial β plane bounded in the zonal direction are used to investigate the equatorial thermocline response to tropical and subtropical wind stress forcing. The results show that the wind stress forcing in the tropical and subtropical region can generate a nearly zonal uniform thermocline depth change in the equatorial region. The response timescale is longer when the wind stress is placed farther away from the equator. There exist latitude bands around 10° 15°N and 10° 15°S where the forcing can cause a relatively large equatorial response. When the forcing is located in the eastern basin, the response timescale is longer and its magnitude is larger than the case when the forcing is located in the western basin. Thus the eastern tropical to subtropical region is a relatively effective area for off-equatorial wind stress to generate an equatorial thermocline response. When the wind stress forcing has a longer period, the response of the equatorial thermocline has a larger magnitude. The results from this study's numerical experiments and the analytical solution are consistent. The present study has implications for the broad-scale ocean atmosphere interaction in the tropical region.

  11. On the origin of late Holocene sea-level highstands within equatorial ocean basins

    NASA Astrophysics Data System (ADS)

    Mitrovica, J. X.; Milne, G. A.

    2002-11-01

    Late Holocene sea-level highstands of amplitude ˜3 m are endemic to equatorial ocean basins. These highstands imply an ongoing and moderate, sub-mm/yr, sea-level fall in the far field of the Late Pleistocene ice cover that has long been linked to the process of glacial isostatic adjustment (GIA; Clark et al., 1978). Mitrovica and Peltier (1991) coined the term 'equatorial ocean syphoning' to describe the GIA-induced sea-level fall and they provided the first physical explanation for the process. They argued that water migrated away from far-field equatorial ocean basins in order to fill space vacated by collapsing forebulges at the periphery of previously glaciated regions. We provide a complete physical explanation for the origin of equatorial ocean syphoning, and the associated development of sea-level highstands, using numerical solutions of the equation that governs meltwater redistribution on spherical, viscoelastic Earth models. In particular, we separate the total predicted sea-level change into contributions associated with ice and meltwater loading effects, and, by doing so, isolate a second mechanism that contributes significantly to the ocean syphoning process. Ocean loading at continental margins induces a 'levering' of continents and a subsidence of offshore regions that has also long been recognized within the GIA literature (Walcott, 1972). We show that the influx of water into the volume created by this subsidence produces a sea-level fall at locations distant from these margins—indeed over the major ocean basins—that is comparable in amplitude to the syphoning mechanism isolated by Mitrovica and Peltier (1991).

  12. No iron fertilization in the equatorial Pacific Ocean during the last ice age

    NASA Astrophysics Data System (ADS)

    Costa, K. M.; McManus, J. F.; Anderson, R. F.; Ren, H.; Sigman, D. M.; Winckler, G.; Fleisher, M. Q.; Marcantonio, F.; Ravelo, A. C.

    2016-01-01

    The equatorial Pacific Ocean is one of the major high-nutrient, low-chlorophyll regions in the global ocean. In such regions, the consumption of the available macro-nutrients such as nitrate and phosphate is thought to be limited in part by the low abundance of the critical micro-nutrient iron. Greater atmospheric dust deposition could have fertilized the equatorial Pacific with iron during the last ice age—the Last Glacial Period (LGP)—but the effect of increased ice-age dust fluxes on primary productivity in the equatorial Pacific remains uncertain. Here we present meridional transects of dust (derived from the 232Th proxy), phytoplankton productivity (using opal, 231Pa/230Th and excess Ba), and the degree of nitrate consumption (using foraminifera-bound δ15N) from six cores in the central equatorial Pacific for the Holocene (0-10,000 years ago) and the LGP (17,000-27,000 years ago). We find that, although dust deposition in the central equatorial Pacific was two to three times greater in the LGP than in the Holocene, productivity was the same or lower, and the degree of nitrate consumption was the same. These biogeochemical findings suggest that the relatively greater ice-age dust fluxes were not large enough to provide substantial iron fertilization to the central equatorial Pacific. This may have been because the absolute rate of dust deposition in the LGP (although greater than the Holocene rate) was very low. The lower productivity coupled with unchanged nitrate consumption suggests that the subsurface major nutrient concentrations were lower in the central equatorial Pacific during the LGP. As these nutrients are today dominantly sourced from the Subantarctic Zone of the Southern Ocean, we propose that the central equatorial Pacific data are consistent with more nutrient consumption in the Subantarctic Zone, possibly owing to iron fertilization as a result of higher absolute dust fluxes in this region. Thus, ice-age iron fertilization in the

  13. No iron fertilization in the equatorial Pacific Ocean during the last ice age.

    PubMed

    Costa, K M; McManus, J F; Anderson, R F; Ren, H; Sigman, D M; Winckler, G; Fleisher, M Q; Marcantonio, F; Ravelo, A C

    2016-01-28

    The equatorial Pacific Ocean is one of the major high-nutrient, low-chlorophyll regions in the global ocean. In such regions, the consumption of the available macro-nutrients such as nitrate and phosphate is thought to be limited in part by the low abundance of the critical micro-nutrient iron. Greater atmospheric dust deposition could have fertilized the equatorial Pacific with iron during the last ice age--the Last Glacial Period (LGP)--but the effect of increased ice-age dust fluxes on primary productivity in the equatorial Pacific remains uncertain. Here we present meridional transects of dust (derived from the (232)Th proxy), phytoplankton productivity (using opal, (231)Pa/(230)Th and excess Ba), and the degree of nitrate consumption (using foraminifera-bound δ(15)N) from six cores in the central equatorial Pacific for the Holocene (0-10,000 years ago) and the LGP (17,000-27,000 years ago). We find that, although dust deposition in the central equatorial Pacific was two to three times greater in the LGP than in the Holocene, productivity was the same or lower, and the degree of nitrate consumption was the same. These biogeochemical findings suggest that the relatively greater ice-age dust fluxes were not large enough to provide substantial iron fertilization to the central equatorial Pacific. This may have been because the absolute rate of dust deposition in the LGP (although greater than the Holocene rate) was very low. The lower productivity coupled with unchanged nitrate consumption suggests that the subsurface major nutrient concentrations were lower in the central equatorial Pacific during the LGP. As these nutrients are today dominantly sourced from the Subantarctic Zone of the Southern Ocean, we propose that the central equatorial Pacific data are consistent with more nutrient consumption in the Subantarctic Zone, possibly owing to iron fertilization as a result of higher absolute dust fluxes in this region. Thus, ice-age iron fertilization in the

  14. NAO and extreme ocean states in the Northeast Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Gleeson, Emily; Gallagher, Sarah; Clancy, Colm; Dias, Frédéric

    2017-02-01

    Large scale atmospheric oscillations are known to have an influence on waves in the North Atlantic. In quantifying how the wave and wind climate of this region may change towards the end of the century due to climate change, it is useful to investigate the influence of large scale oscillations using indices such as the North Atlantic Oscillation (NAO: fluctuations in the difference between the Icelandic low pressure system and the Azore high pressure system). In this study a statistical analysis of the station-based NAO index was carried out using an ensemble of EC-Earth global climate simulations, where EC-Earth is a European-developed atmosphere ocean sea-ice coupled climate model. The NAO index was compared to observations and to projected changes in the index by the end of the century under the RCP4.5 and RCP8.5 forcing scenarios. In addition, an ensemble of EC-Earth driven WAVEWATCH III wave model projections over the North Atlantic was analysed to determine the correlations between the NAO and significant wave height (Hs) and the NAO and extreme ocean states. For the most part, no statistically significant differences were found between the distributions of observed and modelled station-based NAO or in projected distributions of the NAO. Means and extremes of Hs are projected to decrease on average by the end of this century. The 95th percentile of Hs is strongly positively correlated to the NAO. Projections of Hs extremes are location dependent and in fact, under the influence of positive NAO the 20-year return levels of Hs were found to be amplified in some regions. However, it is important to note that the projected decreases in the 95th percentile of Hs off the west coast of Ireland are not statistically significant in one of the RCP4.5 and one of the RCP8.5 simulations (me41, me83) which indicates that there is still uncertainty in the projections of higher percentiles.

  15. Cenozoic Source-to-Sink of the African margin of the Equatorial Atlantic

    NASA Astrophysics Data System (ADS)

    Rouby, Delphine; Chardon, Dominique; Huyghe, Damien; Guillocheau, François; Robin, Cecile; Loparev, Artiom; Ye, Jing; Dall'Asta, Massimo; Grimaud, Jean-Louis

    2016-04-01

    The objective of the Transform Source to Sink Project (TS2P) is to link the dynamics of the erosion of the West African Craton to the offshore sedimentary basins of the African margin of the Equatorial Atlantic at geological time scales. This margin, alternating transform and oblique segments from Guinea to Nigeria, shows a strong structural variability in the margin width, continental geology and relief, drainage networks and subsidence/accumulation patterns. We analyzed this system combining onshore geology and geomorphology as well as offshore sub-surface data. Mapping and regional correlation of dated lateritic paleo-landscape remnants allows us to reconstruct two physiographic configurations of West Africa during the Cenozoic. We corrected those reconstitutions from flexural isostasy related to the subsequent erosion. These geometries show that the present-day drainage organization stabilized by at least 29 Myrs ago (probably by 34 Myr) revealing the antiquity of the Senegambia, Niger and Volta catchments toward the Atlantic as well as of the marginal upwarp currently forming a continental divide. The drainage rearrangement that lead to this drainage organization was primarily enhanced by the topographic growth of the Hoggar swell and caused a major stratigraphic turnover along the Equatorial margin of West Africa. Elevation differences between paleo-landscape remnants give access to the spatial and temporal distribution of denudation for 3 time-increments since 45 Myrs. From this, we estimate the volumes of sediments and associated lithologies exported by the West African Craton toward different segments of the margin, taking into account the type of eroded bedrock and the successive drainage reorganizations. We compare these data to Cenozoic accumulation histories in the basins and discuss their stratigraphic expression according to the type of margin segment they are preserved in.

  16. Mesozoic Source-to-Sink of the African margin of the Equatorial Atlantic

    NASA Astrophysics Data System (ADS)

    ye, jing; Chardon, Dominique; rouby, delphine; Guillocheau, François; Robin, Cecile; Loparev, Artiom; Huyghe, damien; Dall'Asta, Massimo; Brown, Roderick; wildman, mark; webster, david

    2016-04-01

    The objective of the Transform Source to Sink Project (TS2P) is to link the dynamics of the erosion of the West African Craton to the offshore sedimentary basins of the African margin of the Equatorial Atlantic at geological time scales. This margin, alternating transform and oblique segments from Guinea to Nigeria, shows a strong structural variability in the margin width, continental geology and relief, drainage networks and subsidence/accumulation patterns. We analyzed this system combining onshore geology and geomorphology as well as offshore sub-surface data. We produced paleogeographic maps at the scale of West Africa spanning the continental domain and offshore basins since 200 Ma. Mapping spatial and temporal distribution of domains either in erosion (sources) or in accumulation (sinks) document the impact of the successive rifting of Central and Equatorial Atlantic on the physiography of the area. We use low temperature thermochronology dating along three transects perpendicular to the margin (Guinea, Ivory Coast and Benin) to determine periods and domains of denudation in that framework. We compare these data to the Mesozoic accumulation histories in passive margin basins and discuss their stratigraphic expression according to the type of margin segment they are preserved in. Syn-rift architectures (Early Cretaceous) are largely impacted by transform faults that define sub-basins with contrasted width of crustal necking zone (narrower in transform segments than in oblique/normal segments). During the Late Cretaceous post-rift, sedimentary wedges record a transgression along the all margin. Proximal parts of the sedimentary wedge are preserved in basins developing on segments with wide crustal necking zone while they were eroded away in basins developing on narrow segments. As a difference, the Cenozoic wedge is everywhere preserved across the whole width of the margin.

  17. Palaeoceanographic productivity changes in the Eastern Equatorial Atlantic since the penultimate glaciation

    NASA Astrophysics Data System (ADS)

    Lem, Rachael; Marshall, Jim; Leng, Melanie; Marret, Fabienne

    2017-04-01

    A 150,000 year multiproxy record from the eastern equatorial Atlantic, offshore Gabon, has been investigated in order to examine the effects of changing glacial - interglacial climate on marine productivity. Higher δ13C values of the benthic foraminifera Planulina wuellerstorfi are documented during the penultimate glaciation (150 -130 kyr BP) in comparison to the Last Glacial Maximum [LGM] (24.5 - 19 kyr BP). In conjunction with higher CaCO3 and larger variability in the isotopic difference between surface and bottom waters during the penultimate glaciation, this suggests that the eastern equatorial Atlantic was much more productive at this time than the LGM, most likely driven by increased nutrient input through strong bottom water upwelling. The benthic δ18O and planktonic δ18O record of Globigerinoides ruber (white) infer that both the surface and bottom waters were warmer during the penultimate glaciation than the LGM. The sea surface temperature [SST] record assimilated through Mg/Ca analysis of the G. ruber evidences much lower SSTs during the last deglaciation in comparison with other regional records, and with the present day SST, which together with high Fe input, we attribute this to a greatly enhanced discharge of the Ogooué River. Bulk coccolith carbonate δ13C demonstrates a shift towards lower δ13C values from the penultimate glaciation towards present day which does not dovetail the other proxies. The δ18O coccolith record mirrors that of G. ruber during the two glacial periods, but presents much higher isotopic values during the interglacials. We interpret this as a shift in seasonality in the calcification of the coccoliths between glacial and interglacial periods, which in combination with the long term decline in δ13C values reflects a change in the habitat preferences of this phytoplankton over the last glacial - interglacial cycle.

  18. A ‘self-adjustment’ mechanism for mixed-layer heat budget in the equatorial Atlantic cold tongue

    DOE PAGES

    Shi, Yanyan; Wang, Bin; Huang, Wenyu

    2017-01-20

    Wind forcing is one of the most important sources for the oceanic energy cycle and is especially critical to the heat budget of surface mixed layer. The sensitivity of heat budget in the equatorial Atlantic cold tongue (EACT) region (5°S–5°N, 25°W–5°E) to wind forcing and the related mechanism are explored in this study. Based on the experiments forced by different wind forcing from both reanalysis and idealized datasets, it is revealed that the contribution ratio for each of the dominant physical processes in the heat budget is insensitive (the variations within 1% of the mean) to the variations in themore » local winds (the largest variation is about 20% of the mean) over the EACT region. Therefore, a ‘self-adjustment’ mechanism exists in the mixed-layer heat budget: as local zonal winds over the EACT region strengthen (weaken), both the cooling effects of turbulent mixing and the combined warming effects of surface net heat flux and zonal advection simultaneously increase (decrease) by nearly the same percentage and thus their contribution ratios are kept constant. Finally, owing to the impact of meridional winds on each term of heat budget can be neglected, the above mechanism is also tenable under the situation when the local meridional winds change.« less

  19. Nutrient characteristics of the water masses and their seasonal variability in the eastern equatorial Indian Ocean.

    PubMed

    Sardessai, S; Shetye, Suhas; Maya, M V; Mangala, K R; Prasanna Kumar, S

    2010-01-01

    Nutrient characteristics of four water masses in the light of their thermohaline properties are examined in the eastern Equatorial Indian Ocean during winter, spring and summer monsoon. The presence of low salinity water mass with "Surface enrichments" of inorganic nutrients was observed relative to 20 m in the mixed layer. Lowest oxygen levels of 19 microM at 3 degrees N in the euphotic zone indicate mixing of low oxygen high salinity Arabian Sea waters with the equatorial Indian Ocean. The seasonal variability of nutrients was regulated by seasonally varying physical processes like thermocline elevation, meridional and zonal transport, the equatorial undercurrent and biological processes of uptake and remineralization. Circulation of Arabian Sea high salinity waters with nitrate deficit could also be seen from low N/P ratio with a minimum of 8.9 in spring and a maximum of 13.6 in winter. This large deviation from Redfield N/P ratio indicates the presence of denitrified high salinity waters with a seasonal nitrate deficit ranging from -4.85 to 1.52 in the Eastern Equatorial Indian Ocean. 2010 Elsevier Ltd. All rights reserved.

  20. 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.

  1. Seasonal variation of the surface North Equatorial Countercurrent (NECC) in the western Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Zhao, Jun; Li, Yuanlong; Wang, Fan

    2016-11-01

    The North Equatorial Countercurrent (NECC) is an important zonal flow in the upper circulation of the tropical Pacific Ocean, which plays a vital role in the heat budget of the western Pacific warm pool. Using satellite-derived data of ocean surface currents and sea surface heights (SSHs) from 1992 to 2011, the seasonal variation of the surface NECC in the western tropical Pacific Ocean was investigated. It was found that the intensity (INT) and axis position (Y CM ) of the surface NECC exhibit strikingly different seasonal fluctuations in the upstream (128°-136°E) and downstream (145°-160°E) regions. Of the two regions, the seasonal cycle of the upstream NECC shows the greater interannual variability. Its INT and YCM are greatly influenced by variations of the Mindanao Eddy, Mindanao Dome (MD), and equatorial Rossby waves to its south. Both INT and Y CM also show semiannual signals induced by the combined effects of equatorial Rossby waves from the Central Pacific and local wind forcing in the western Pacific Ocean. In the downstream region, the variability of the NECC is affected by SSH anomalies in the MD and the central equatorial Pacific Ocean. Those in the MD region are especially important in modulating the YCM of the downstream NECC. In addition to the SSH-related geostrophic flow, zonal Ekman flow driven by meridional wind stress also plays a role, having considerable impact on INT variability of the surface NECC. The contrasting features of the variability of the NECC in the upstream and downstream regions reflect the high complexity of regional ocean dynamics.

  2. Testing the iron hypothesis in ecosystems of the equatorial Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Martin, J. H.; Coale, K. H.; Johnson, K. S.; Fitzwater, S. E.; Gordon, R. M.; Tanner, S. J.; Hunter, C. N.; Elrod, V. A.; Nowicki, J. L.; Coley, T. L.; Barber, R. T.; Lindley, S.; Watson, A. J.; van Scoy, K.; Law, C. S.; Liddicoat, M. I.; Ling, R.; Stanton, T.; Stockel, J.; Collins, C.; Anderson, A.; Bidigare, R.; Ondrusek, M.; Latasa, M.; Millero, F. J.; Lee, K.; Yao, W.; Zhang, J. Z.; Friederich, G.; Sakamoto, C.; Chavez, F.; Buck, K.; Kolber, Z.; Greene, R.; Falkowski, P.; Chisholm, S. W.; Hoge, F.; Swift, R.; Yungel, J.; Turner, S.; Nightingale, P.; Hatton, A.; Liss, P.; Tindale, N. W.

    1994-09-01

    The idea that iron might limit phytoplankton growth in large regions of the ocean has been tested by enriching an area of 64 km2 in the open equatorial Pacific Ocean with iron. This resulted in a doubling of plant biomass, a threefold increase in chlorophyll and a fourfold increase in plant production. Similar increases were found in a chlorophyll-rich plume down-stream of the Galapagos Islands, which was naturally enriched in iron. These findings indicate that iron limitation can control rates of phytoplankton productivity and biomass in the ocean.

  3. The Atlantic Equatorial Thermocline as simulated by the Brazilian Earth System Model: known biases and possible causes

    NASA Astrophysics Data System (ADS)

    Giarolla, E.; Nobre, P.; Malagutti, M.

    2013-05-01

    As a result of a coordinated effort of several institutions in Brazil, the Brazilian Earth System Model has been developed to help the investigation of global climate changes, its effects and impacts on society. The first version of this model, here named Brazilian Earth System Model - Ocean-Atmosphere version 2.3 (BESM-OA2.3), followed the criteria for participation in the Coupled Models Intercomparison Project 5 (CMIP5) protocol, simulating the behavior of the coupled ocean-atmosphere system on decadal time scales under varying green house gases concentrations in the atmosphere. Extended runs with over 2,000 years of ensemble members showed many coherent results, such as the response of the model to increasing atmospheric CO2 concentrations in a consistent manner. In spite of that, the model still has biases and discrepancies when compared to observations, some of them also detected in other global coupled ocean-atmosphere models. As an example of known bias, the thermocline along the Atlantic equator flattens after the second year of simulation. In other words, it anomalously deepens at the eastern region near the African coast after some months. This issue is observed in all CMIP5-based experiments made with the BESM-OA2.3. However, a newer version of the BESM-OA, with updated microphysics parameterizations and the Integrated Biosphere Simulator (IBIS) included, has shown promising results, i.e., the thermocline tends to maintain its inclination in the second year better than the first version of BESM-OA. In this work we discuss the possible causes of the thermocline flattening comparing simulations of both model versions. We don't have conclusive explanations since the study is still in progress, but some results indicate that the seasonal eastward shift of the zonal wind reversion (represented as the zero zonal wind line) at the Atlantic equator, in April-May, is better represented in the newest version of the model. With more realistic winds at the equator

  4. The role of Ekman flow and planetary waves in the oceanic cross-equatorial heat transport

    NASA Technical Reports Server (NTRS)

    Schopf, P. S.

    1980-01-01

    A numerical model is used to mechanistically simulate the oceans' seasonal cross-equatorial heat transport. The basic process of Ekman pumping and drift is able to account for a large amount of the cross-equatorial flux. Increased easterly wind stress in the winter hemisphere causes Ekman surface drift poleward, while decreased easterly stress allows a reduction in the poleward drift in the summer hemisphere. The addition of planetary and gravity waves to this model does not alter the net cross-equatorial flow, although the planetary waves are clearly seen. On comparison with Oort and Vonder Haar (1976), this adiabatic advective redistribution of heat is seen to be plausible up to 10-20 deg N, beyond which other dynamics and thermodynamics are indicated.

  5. AtlantOS - Optimizing and Enhancing the Integrated Atlantic Ocean Observing System

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    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 observing by using the Framework of Ocean Observing to obtain an international, more sustainable, more efficient, more integrated, and fit-for-purpose system. Hence, the AtlantOS initiative will have a long-lasting and sustainable contribution to the societal, economic and scientific benefit arising from this integrated approach. This 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 and authority of ocean information, v) to strengthen the Global Ocean Observing System (GOOS) and to sustain observing systems that are critical for the Copernicus Marine Environment Monitoring Service and its applications and vi) to contribute to the aims of the Galway Statement on Atlantic

  6. 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.

  7. A deeper respired carbon pool in the glacial equatorial Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Bradtmiller, L. I.; Anderson, R. F.; Sachs, J. P.; Fleisher, M. Q.

    2010-11-01

    Atmospheric pCO 2 was approximately 80 ppm lower during the last glacial period than during pre-industrial times. Identifying the fate of that carbon has been one of the great challenges in paleoceanography. We present evidence from ten equatorial Pacific Ocean sediment cores to show that the deep Pacific Ocean likely stored more carbon during the last glacial period than the Holocene. The concentration of the redox-sensitive metal uranium (U) in sediments was systematically greater during the last glacial period than during the Holocene, indicating more reducing conditions in glacial-age sediments. Reconstructions of biogenic opal flux indicate that changes in U distribution were not the result of changes in biological productivity and the ensuing rain of organic carbon to the sea floor, which also affects the redox conditions of the sediments. Together, these results lead to the interpretation that bottom water in the equatorial Pacific during the glacial period had significantly lower oxygen concentration than during the Holocene, and a correspondingly greater level of respired CO 2. This conclusion is supported by evidence for greater preservation of brassicasterol, a biomarker produced by diatoms, in glacial-age sediments of the eastern equatorial Pacific. The presence of additional respired CO 2 in the glacial deep ocean would have lowered atmospheric pCO 2 by 1) increasing the total storage of CO 2 in the glacial ocean and 2) increasing ocean alkalinity following a transient carbonate dissolution event. Our results are consistent with recently published data from the North Pacific Ocean; this suggests that increased carbon storage in the glacial deep Pacific Ocean was a basin-wide phenomenon, consistent with a large-scale transfer of carbon to the deep ocean during glacial periods.

  8. Mesopelagic fishes across the tropical and equatorial Atlantic: Biogeographical and vertical patterns

    NASA Astrophysics Data System (ADS)

    Olivar, M. Pilar; Hulley, P. Alexander; Castellón, Arturo; Emelianov, Mikhail; López, Cristina; Tuset, Víctor M.; Contreras, Tabit; Molí, Balbina

    2017-02-01

    In this investigation we analysed the changes in fish species occurrences and relative abundances across the tropical and equatorial Atlantic, and their vertical distribution patterns in relation to the different environmental scenarios. The study covers a wide region encompassing different water masses, and marked differences in productivity, from an oligotrophic zone close to the Brazilian coast, to a very productive upwelling region close to the Northwest African upwelling. Fishes were collected with a medium-sized midwater trawl (Mesopelagos), complemented by hauls made with a macrozooplankton net (MOCNESS). Species richness in the region was higher than in subtropical, temperate and cold regions. The total number of species and their overall abundance was lower in the stations closer to the Brazilian coast. Abundant species across the entire region were the gonostomatids Cyclothone alba, Cyclothone acclinidens, Cyclothone pallida and Cyclothone pseudopallida, the myctophid Lampanyctus alatus, the sternoptychid Sternoptyx diaphana, and the phosichthyid Vinciguerria nimbaria. The occurrences and abundances of C. parapallida, Lampanyctus nobilis and Lepidophanes guentheri were related to zones where AAIW waters occupied the mesopelagic layers, while other species such as Cyclothone livida and Polyipnus polli increased their abundance when AAIW disappears from their living depths. The presence of Eastern North Atlantic Central Water (ENACW) was associated with the occurrence of several myctophids (Benthosema glaciale, Ceratoscopelus maderensis, Diaphus holti, Diaphus rafinesquii, Hygophum hygomii, Lampanyctus crocodilus, Myctophum punctatum, Symbolophorus veranyi), and the gonostomatid Cyclothone braueri. In spite of the important differences in hydrographic features across the tropical and equatorial Atlantic, all stations showed either the general night migration into the epipelagic layers carried out by myctophids, phosicthyids, and some stomiids, or the

  9. Seasonal cycle of cross-equatorial flow in the central Indian Ocean

    NASA Astrophysics Data System (ADS)

    Wang, Yi; McPhaden, Michael J.

    2017-05-01

    This study investigates the seasonal cycle of meridional currents in the upper layers of central equatorial Indian Ocean using acoustic Doppler current profiler (ADCP) and other data over the period 2004-2013. The ADCP data set collected along 80.5°E is the most comprehensive collection of direct velocity measurements in the central Indian Ocean to date, providing new insights into the meridional circulation in this region. We find that mean volume transport is southward across the equator in the central Indian Ocean in approximate Sverdrup balance with the wind stress curl. In addition, mean westerly wind stress near the equator drives convergent Ekman flow in the surface layer and subsurface divergent geostrophic flow in the thermocline at 50-150 m depths. In response to a mean northward component of the surface wind stress, the maximum surface layer convergence is shifted off the equator to between 0.5° and 1°N. Evidence is also presented for the existence of a shallow equatorial roll consisting of a northward wind-driven surface drift overlaying the southward directed subsurface Sverdrup transport. Seasonal variations are characterized by cross-equatorial transports flowing from the summer to the winter hemisphere in quasi-steady Sverdrup balance with the wind stress curl. In addition, semiannually varying westerly monsoon transition winds lead to semiannual enhancements of surface layer Ekman convergence and geostrophic divergence in the thermocline. These results quantify expectations from ocean circulation theories for equatorial Indian Ocean meridional circulation patterns with a high degree of confidence given the length of the data records.

  10. 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, Zhenya; Lee, Sang-Ki; Wang, Chunzai; Kirtman, Ben P.; Qiao, Fangli

    2015-12-01

    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.

  11. Role of oceanic circulation on contaminant lead distribution in the South Atlantic

    NASA Astrophysics Data System (ADS)

    Alleman, L. Y.; Church, T. M.; Ganguli, P.; Véron, A. J.; Hamelin, B.; Flegal, A. R.

    Both the relatively high lead concentrations and their characteristic anthropogenic isotopic compositions attest to the widespread contamination of industrial lead in the western Equatorial and South Atlantic Ocean. Spatial gradients in those isotopic signatures evidence the conservative lateral transport of lead in oceanic water masses, while the discrete isotopic signatures in deep oceanic waters substantiate the complementary hypothesis that the release of lead from settling particles is relatively small on a decadal time-scale. Specifically, the relatively low radiogenic lead (e.g., 206Pb/ 207Pb=1.148±0.009) in the Lower-North Atlantic Deep Water (l-NADW) south of 10° North is primarily attributed to US industrial lead emitted in the Northern Hemisphere prior to 1965, and the more radiogenic lead (e.g., 206Pb/ 207Pb=1.180±0.006) in the Upper-North Atlantic Deep Water (u-NADW) is primarily attributed to subsequent industrial lead emissions in that hemisphere. In contrast, the relatively radiogenic lead (e.g., 206Pb/ 207Pb=1.186±0.007) in the Antarctic Bottom Water (AABW) seemingly reflects a mixture of natural and anthropogenic lead sources within the Southern Hemisphere; and its isotopic dissimilarity with that (e.g., 206Pb/ 207Pb=1.159±0.002) of Antarctic Intermediate Water (AAIW) and the AABW may be due to differences in either their aeolian or water-mass inputs.

  12. 78 FR 34879 - Special Local Regulations for Marine Events, Atlantic City Offshore Race, Atlantic Ocean...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-11

    .... The marine event formerly originated on the third Sunday in July, but now is on the fourth Sunday in... Sunday in July on the waters of the Atlantic Ocean at Atlantic City, New Jersey. The regulation listing.... The date listed in the Table has the marine event on the third Sunday in July. However, this temporary...

  13. Surface and subsurface oceanic variability observed in the eastern equatorial Indian Ocean during three consecutive Indian Ocean dipole events: 2006 - 2008

    NASA Astrophysics Data System (ADS)

    Iskandar, I.; Mardiansyah, W.; Setiabudidaya, D.; Affandi, A. K.; Syamsuddin, F.

    2014-09-01

    8-year and 4-year long velocity time series records from the equatorial Indian Ocean successfully captured, for the first time, complete evolution of subsurface currents associated with three consecutive Indian Ocean Dipole (IOD) events in 2006 - 2008. It is found that strong eastward subsurface zonal currents in the layer between about 90 m and 150 m were observed, which were opposite to the normal conditions. Vertical structure of the zonal currents resembles that of the typical zonal currents in the equatorial Pacific with an eastward subsurface current lies beneath the surface westward currents. This vertical structure of the zonal currents was associated with anomalous easterly winds along the equatorial Indian Ocean during the maturing phase of the IOD events. In addition, subsurface temperature structures obtained from RAMA buoy network show negative temperature anomalies preceded the surface temperature evolution associated with the IOD events. The negative subsurface temperature anomaly lasted for several months before it changes into positive anomaly as the IOD terminated. The surface temperature structure indicated by the Dipole Mode Index (DMI) revealed that the 2006 IOD was a strong event, while the 2007 and 2008 events were weaker and short-lived events. The evolution of the IOD events were linked to the dynamics of oceanic equatorial wave. It is found that upwelling equatorial Kelvin waves forced by anomalous easterly wind stress play an important role in generating cooling tendency during the development and maturing phase of the IOD events. The demise of the IOD events, on the other hand, was linked to eastern-boundary-reflected Rossby waves that terminated the cooling tendency in the eastern Indian Ocean induced by the wind-forced Kelvin waves. Weakening of the zonal heat advection, then, provided a favor condition for the surface heat flux to warm the sea surface temperature in the eastern equatorial Indian Ocean.

  14. Biogeochemical linkage between atmosphere and ocean in the eastern equatorial Pacific Ocean: Results from the EqPOS research cruise

    NASA Astrophysics Data System (ADS)

    Furutani, H.; Inai, Y.; Aoki, S.; Honda, H.; Omori, Y.; Tanimoto, H.; Iwata, T.; Ueda, S.; Miura, K.; Uematsu, M.

    2012-12-01

    Eastern equatorial Pacific Ocean is a unique oceanic region from several biogeochemical points of view. It is a remote open ocean with relatively high marine biological activity, which would result in limited influence of human activity but enhanced effect of marine natural processes on atmospheric composition. It is also characterized as high nutrient low chlorophyll (HNLC) ocean, in which availability of trace metals such as iron and zinc limits marine primary production and thus atmospheric deposition of these trace elements to the ocean surface is expected to play an important role in regulating marine primary production and defining unique microbial community. High sea surface temperature in the region generates strong vertical air convection which efficiently brings tropospheric atmospheric composition into stratosphere. In this unique eastern equatorial Pacific Ocean, EqPOS (Equatorial Pacific Ocean and Stratospheric/Tropospheric Atmospheric Study) research cruise was organized as a part of SOLAS Japan activity to understand biogeochemical ocean-atmospheric interaction in the region. Coordinated atmospheric, oceanic, and marine biological observations including sampling/characterization of thin air-sea interfacial layer (sea surface microlayer: SML) and launching large stratospheric air sampling balloons were carried out on-board R/V Hakuho Maru starting from 29 January for 39 days. Biogeochemically important trace/long-lived gases such as CO2, dimethyl sulfide (DMS), and some volatile organic carbons (VOCs) both in the atmosphere and seawater were continuously monitored and their air-sea fluxes were also observed using gradient and eddy-covariance techniques. Atmospheric gas measurement of CO2, CH4, N2O, SF6, CO, H2, Ar and isotopic composition of selected gases were further extended to stratospheric air by balloon-born sampling in addition to a vertical profiling of O3, CO2, and H2O with sounding sondes. Physical and chemical properties of marine

  15. 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.

  16. Atmospheric Blocking and Atlantic Multi-Decadal Ocean Variability

    NASA Technical Reports Server (NTRS)

    Haekkinen, Sirpa; Rhines, Peter B.; Worthlen, Denise L.

    2011-01-01

    Based on the 20th century atmospheric reanalysis, winters with more frequent blocking, in a band of blocked latitudes from Greenland to Western Europe, are found to persist over several decades and correspond to a warm North Atlantic Ocean, in-phase with Atlantic multi-decadal ocean variability. Atmospheric blocking over the northern North Atlantic, which involves isolation of large regions of air from the westerly circulation for 5 days or more, influences fundamentally the ocean circulation and upper ocean properties by impacting wind patterns. Winters with clusters of more frequent blocking between Greenland and western Europe correspond to a warmer, more saline subpolar ocean. The correspondence between blocked westerly winds and warm ocean holds in recent decadal episodes (especially, 1996-2010). It also describes much longer-timescale Atlantic multidecadal ocean variability (AMV), including the extreme, pre-greenhouse-gas, northern warming of the 1930s-1960s. The space-time structure of the wind forcing associated with a blocked regime leads to weaker ocean gyres and weaker heat-exchange, both of which contribute to the warm phase of AMV.

  17. The distribution of dissolved iron in the West Atlantic Ocean.

    PubMed

    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 (17,500 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.

  18. 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

  19. 50 CFR 600.520 - Northwest Atlantic Ocean fishery.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false Northwest Atlantic Ocean fishery. 600.520 Section 600.520 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND...—(1) Allocations. Foreign vessels may engage in fishing only in accordance with applicable...

  20. The variability of the surface wind field in the equatorial Pacific Ocean: Criteria for satellite measurements

    NASA Technical Reports Server (NTRS)

    Halpern, D.

    1984-01-01

    The natural variability of the equatorial Pacific surface wind field is described from long period surface wind measurements made at three sites along the equator (95 deg W, 109 deg 30 W, 152 deg 30 W). The data were obtained from surface buoys moored in the deep ocean far from islands or land, and provide criteria to adequately sample the tropical Pacific winds from satellites.

  1. 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).

  2. Cloud Streets over the Atlantic Ocean

    NASA Image and Video Library

    2017-09-27

    In the midst of a cold snap that sent temperatures 20–40°F (11–22°C) below normal across much of the United States, the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite captured this image of cloud streets over the Atlantic Ocean on January 7, 2014. Cloud streets—long parallel bands of cumulus clouds—form when cold air blows over warmer waters and a warmer air layer (or temperature inversion) rests over the top of both. The comparatively warm water gives up heat and moisture to the cold air above, and columns of heated air called thermals naturally rise through the atmosphere. The temperature inversion acts like a lid, so when the rising thermals hit it, they roll over and loop back on themselves, creating parallel cylinders of rotating air. As this happens, the moisture cools and condenses into flat-bottomed, fluffy-topped cumulus clouds that line up parallel to the direction of the prevailing wind. On January 7, the winds were predominantly out of the northwest. Cloud streets can stretch for hundreds of kilometers if the land or water surface underneath is uniform. Sea surface temperature need to be at least 40°F (22°C) warmer than the air for cloud streets to form. More info: earthobservatory.nasa.gov/NaturalHazards/view.php?id=82800 NASA Earth Observatory image courtesy Jeff Schmaltz LANCE/EOSDIS MODIS Rapid Response Team, GSFC. Caption by Adam Voiland. Instrument: Terra - MODIS Credit: NASA Earth Observatory 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

  3. Phanerozoic burial, uplift and denudation of the Equatorial Atlantic margin of South America

    NASA Astrophysics Data System (ADS)

    Japsen, Peter; Bonow, Johan M.; Green, Paul F.; dall'Asta, Massimo; Roig, Jean-Yves; Theveniaut, Hervé

    2017-04-01

    We have initiated a study aimed at understanding the history of burial, uplift and denudation of the South American Equatorial Atlantic Margin (SAEAM Uplift) including the Guiana Shield to provide a framework for investigating the hydrocarbon prospectivity of the offshore region. We report first results including observations from fieldwork at the northern and southern flank of the Guiana Shield. The study combines apatite fission-track analysis (AFTA) and vitrinite reflectance data from samples of outcrops and drillcores, sonic velocity data from drill holes and stratigraphic landscape analysis (mapping of peneplains) - all constrained by geological evidence, following the methods of Green et al. (2013). The study will thus combine the thermal history from AFTA data with the denudation history from stratigraphic landscape analysis to provide magnitudes and timing of vertical movements (Japsen et al. 2012, 2016). Along the Atlantic margin of Suriname and French Guiana, tilted and truncated Lower Cretaceous strata rest on Precambrian basement (Sapin et al. 2016). Our AFTA data show that the basement underwent Mesozoic exhumation prior to deposition of the Lower Cretaceous cover. Sub-horizontal peneplains define the landscape of the Guiana Shield at elevations up to 500 m a.s.l. As these sub-horizontal peneplains truncate the tilted, sub-Cretaceous surface along the Atlantic margin, these peneplains were therefore formed and uplifted in post-Cretaceous time. This interpretation is in good agreement with our AFTA data that define Paleogene exhumation along the margin and with the results of Theveniaut and Freyssinet (2002) who used palaeomagnetic data to conclude that bauxitic surfaces across basement at up to 400 m a.s.l. on the Guiana Shield formed during the Palaeogene. Integration of the results from AFTA with stratigraphic landscape analysis (currently in progress) and geological evidence will provide a robust reconstruction of the tectonic development of the

  4. Structure and dynamics of the Indian-Ocean cross-equatorial cell

    NASA Astrophysics Data System (ADS)

    Miyama, Toru; McCreary, Julian P.; Jensen, Tommy G.; Loschnigg, Johannes; Godfrey, Stuart; Ishida, Akio

    2003-07-01

    The cross-equatorial cell (CEC) in the Indian Ocean is a shallow ( z≳-500 m) meridional overturning circulation, consisting of northward flow of southern-hemisphere thermocline water, upwelling in the northern hemisphere, and a return flow of surface water. In this study, several types of ocean models, varying in complexity from a 1 1/2-layer analytic model to a state-of-the-art general circulation model (GCM), are used to investigate CEC structure and its dynamics. Pathways are illustrated by tracking model drifters from the northern-hemisphere upwelling regions, both forwards in time to follow the surface pathways and backwards in time to follow the subsurface flows. In the subsurface branch, cross-equatorial flow occurs via a western-boundary current, where strong horizontal mixing can alter the sign of its potential vorticity. In contrast, surface pathways cross the equator in the interior ocean at almost all longitudes. Sources of CEC water are flow into the basin in the southeastern ocean, subtropical subduction, and the Indonesian Throughflow. The models differ in which source is most prominent, a consequence of their different parameterizations of vertical-mixing processes and basin boundary conditions. The surface, cross-equatorial branch is driven by the annual-mean component of the zonal wind stress τx. It is predominantly antisymmetric about the equator with westerlies (easterlies) north (south) of the equator, and so is roughly proportional to latitude y. The resulting negative wind curl drives a southward Sverdrup flow across the equator. For a τx that is exactly proportional to y, the Ekman pumping velocity is identically zero; as a consequence, no geostrophic currents are generated by the wind, and the Sverdrup transport is equal to the Ekman drift. In GCM solutions, the southward, cross-equatorial flow occurs just below the surface ( z<-100 m), typically beneath a northward surface current, so that there is a shallow, cross-equatorial "roll

  5. On the Cause of Eastern Equatorial Pacific Ocean T-S Variations Associated with El Nino

    NASA Technical Reports Server (NTRS)

    Wang, Ou; Fukumori, Ichiro; Lee, Tong; Cheng, Benny

    2004-01-01

    The nature of observed variations in temperature-salinity (T-S) relationship between El Nino and non-El Nino years in the pycnocline of the eastern equatorial Pacific Ocean (NINO3 region, 5(deg)S-5(deg)N, 150(deg)W-90(deg)W) is investigated using an ocean general circulation model. The origin of the subject water mass is identified using the adjoint of a simulated passive tracer. The higher salinity during El Nino is attributed to larger convergence of saltier water from the Southern Hemisphere and smaller convergence of fresher water from the Northern Hemisphere.

  6. On the Cause of Eastern Equatorial Pacific Ocean T-S Variations Associated with El Nino

    NASA Technical Reports Server (NTRS)

    Wang, Ou; Fukumori, Ichiro; Lee, Tong; Cheng, Benny

    2004-01-01

    The nature of observed variations in temperature-salinity (T-S) relationship between El Nino and non-El Nino years in the pycnocline of the eastern equatorial Pacific Ocean (NINO3 region, 5(deg)S-5(deg)N, 150(deg)W-90(deg)W) is investigated using an ocean general circulation model. The origin of the subject water mass is identified using the adjoint of a simulated passive tracer. The higher salinity during El Nino is attributed to larger convergence of saltier water from the Southern Hemisphere and smaller convergence of fresher water from the Northern Hemisphere.

  7. Observations of the Mindanao current during the Western Equatorial Pacific Ocean Circulation Study

    NASA Astrophysics Data System (ADS)

    Lukas, Roger; Firing, Eric; Hacker, Peter; Richardson, Philip L.; Collins, Curtis A.; Fine, Rana; Gammon, Richard

    1991-04-01

    The Western Equatorial Pacific Ocean Circulation Study (WEPOCS) III expedition was conducted from June 18 through July 31, 1988, in the far western equatorial Pacific Ocean to observe the low-latitude western boundary circulation there, with emphasis on the Mindanao Current. This survey provides the first quasi-synoptic set of current measurements which resolve all of the important upper-ocean currents in the western tropical Pacific. Observations were made of the temperature, salinity, dissolved oxygen, and current profiles with depth; of water mass properties including transient tracers; and of evolving surface flows with a dense array of Lagrangian drifters. This paper provides a summary of the measurements and a preliminary description of the results. The Mindanao Current was found to be a narrow, southward-flowing current along the eastward side of the southern Philippine Islands, extending from 14°N to the south end of Mindanao near 6°N, where it then separates from the coast and penetrates into the Celebes Sea. The current strengthens to the south and is narrowest at 10°N. Direct current measurements reveal transports in the upper 300 m increasing from 13 Sv to 33 Sv (1 Sverdrup = 1 × 106 m3 s-1) between 10°N and 5.5°N. A portion of the Mindanao Current appears to recurve cyclonically in the Celebes Sea to feed the North Equatorial Countercurrent, merging with waters from the South Equatorial Current and the New Guinea Coastal Undercurrent. Another portion of the Mindanao Current appears to flow directly into the NECC without entering the Celebes Sea. The turning of the currents into the NECC is associated with the Mindanao and Halmahera eddies.

  8. Atlantic Ocean CARINA data: overview and salinity adjustments

    SciTech Connect

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

    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 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 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 inventories

  9. 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

  10. Integrated bio-magnetostratigraphy of ODP Site 709 (equatorial Indian Ocean).

    NASA Astrophysics Data System (ADS)

    Villa, Giuliana; Fioroni, Chiara; Florindo, Fabio

    2015-04-01

    Over the last decade, calcareous nannofossil biostratigraphy of the lower Eocene-Oligocene sediments has shown great potential, through identification of several new nannofossil species and bioevents (e.g. Fornaciari et al., 2010; Bown and Dunkley Jones, 2012; Toffanin et al., 2013). These studies formed the basis for higher biostratigraphic resolution leading to definition of a new nannofossil biozonation (Agnini et al., 2014). In this study, we investigate the middle Eocene-lower Oligocene sediments from ODP Hole 709C (ODP Leg 115) by means of calcareous nannofossils and magnetostratigraphy. Ocean Drilling Program (ODP) Site 709 was located in the equatorial Indian Ocean and biostratigraphy has been investigated in the nineties (Okada, 1990; Fornaciari et al., 1990) while paleomagnetic data from the Initial Report provided only a poorly constrained magnetostratigraphic interpretation, thus the cored succession was dated only by means of biostratigraphy. Our goal is to test the reliability in the Indian Ocean of the biohorizons recently identified at Site 711 (Fioroni et al., in press), by means of high resolution sampling, new taxonomic updates, quantitative analyses on calcareous nannofossils allowed to increase the number of useful bioevents and to compare their reliability and synchroneity. The new magnetostratigraphic analyses and integrated stratigraphy allow also to achieve an accurate biochronology of the time interval spanning Chrons C20 (middle Eocene) and C12 (early Oligocene). In addition, this equatorial site represents an opportunity to study the carbonate accumulation history and the large fluctuations of the carbonate compensation depth (CCD) during the Eocene (e.g. Pälike et al., 2012). The investigated interval encompasses the Middle Eocene Climatic Optimum (MECO), and the long cooling trend that leads to the Oligocene glacial state. By means of our new bio-magnetostratigraphic data and paleoecological results we provide further insights on

  11. Competition for polymers among heterotrophic bacteria, isolated from particles of the Equatorial Atlantic.

    PubMed

    Berkenheger, Imke; Fischer, Ulrich

    2004-03-01

    Three heterotrophic bacterial strains, isolated from organic particles of the upper water column of the Equatorial Atlantic, taken during a cruise on the R/V METEOR (1997), were investigated concerning their physiological and phylogenetic properties using classic microbiological and modern molecular-biological methods. All isolates are gram-negative rods able to use polymers such as cellulose, chitin or starch as sole carbon source. The phylogeny of these isolates was investigated by fluorescence in situ hybridization (FISH) and 16S rDNA sequencing. The three isolated strains belong to the Cytophaga/Flavobacteria, gamma-Proteobacteria (Marinobacter sp.), and alpha-Proteobacteria (Sulfitobacter pontiacus). In order to study succession during growth on polymers naturally occurring in marine habitats, FISH was used as a new approach to detect cells from different phylogenetic clusters in the course of a single growth experiment. Mixed cultures consisting of the isolated strains in equal amounts were incubated with cellulose, chitin or starch. Isolate 4301-10/2, a member of the gamma-Proteobacteria, dominated in mixed cultures growing on cellulose, chitin, or starch after only 10 days, with 55, 60, and 95%, respectively, of cells hybridizing with 4,6-diamidino-2-phenylindole (DAPI).

  12. Occurrence of tar balls on the beaches of Fernando de Noronha Island, South Equatorial Atlantic.

    PubMed

    Baptista Neto, José Antônio; da Costa Campos, Thomas Ferreira; de Andrade, Carala Danielle Perreira; Sichel, Susanna Eleonora; da Fonseca, Estefan Monteiro; Motoki, Akihisa

    2014-12-01

    This work reports on the widespread occurrence of tar balls on a pebble beach of Sueste Bay on Fernando de Noronha Island, a Brazilian national marine park and a preserve in the South Equatorial Atlantic. Environmental regulations preclude regular visitors to the Sueste Bay beach, and the bay is a pristine area without any possible or potential sources of petroleum in the coastal zone. In this work, these tar balls were observed for the first time as they occurred as envelopes around beach pebbles. They are black in color, very hard, have a shell and coral fragment armor, and range in average size from 2 to 6 cm. The shape of the majority of the tar balls is spherical, but some can also be flattened ellipsoids. The polycyclic aromatic hydrocarbon analyses of the collected samples revealed the characteristics of a strongly weathered material, where only the most persistent compounds were detected: chrysene, benzo(b,k)fluoranthene, dibenzo(a,h)antracene and benzo(a)pyrene.

  13. Gas exchange and CO2 flux in the tropical Atlantic Ocean determined from Rn-222 and pCO2 measurements

    NASA Technical Reports Server (NTRS)

    Smethie, W. M., Jr.; Takahashi, T.; Chipman, D. W.; Ledwell, J. R.

    1985-01-01

    The piston velocity for the tropical Atlantic Ocean has been determined from 29 radon profiles measured during the TTO Tropical Atlantic Study. By combining these data with the pCO2 data measured in the surface water and air samples, the net flux of CO2 across the sea-air interface has been calculated for the tropical Atlantic. The dependence of the piston velocity on wind speed is discussed, and possible causes for the high sea-to-air CO2 flux observed in the equatorial zone are examined.

  14. Gas exchange and CO2 flux in the tropical Atlantic Ocean determined from Rn-222 and pCO2 measurements

    NASA Technical Reports Server (NTRS)

    Smethie, W. M., Jr.; Takahashi, T.; Chipman, D. W.; Ledwell, J. R.

    1985-01-01

    The piston velocity for the tropical Atlantic Ocean has been determined from 29 radon profiles measured during the TTO Tropical Atlantic Study. By combining these data with the pCO2 data measured in the surface water and air samples, the net flux of CO2 across the sea-air interface has been calculated for the tropical Atlantic. The dependence of the piston velocity on wind speed is discussed, and possible causes for the high sea-to-air CO2 flux observed in the equatorial zone are examined.

  15. 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

    corresponds well to the average oxygen ages for the well ventilated waters. However, in the density ranges of the suboxic OMZs the turn-over time substantially increases. This indicates that reduced ventilation in the outcrop is directly related to the existence of suboxic OMZs, but they are not obviously related to enhanced consumption indicated by the oxygen ages. The turn-over time suggests that the lower thermocline of the North Atlantic would be suboxic but at present this is compensated by the import of water from the well ventilated South Atlantic. The turn-over time approach itself is independent of details of ocean transport pathways. Instead the geographical location of the OMZ is to first order determined by: (i) the patterns of upwelling, either through Ekman or equatorial divergence, (ii) the regions of general sluggish horizontal transport at the eastern boundaries, and (iii) to a lesser extent to regions with high productivity as indicated through ocean colour data.

  16. Toxic Trichodesmium bloom occurrence in the southwestern South Atlantic Ocean.

    PubMed

    Sacilotto Detoni, Amália Maria; Costa, Luiza Dy Fonseca; Pacheco, Lucas Abrão; Yunes, João Sarkis

    2016-02-01

    Harmful Trichodesmium blooms have been reported on the continental slope of the southwestern South Atlantic Ocean; we sampled six such blooms. The highest saxitoxin concentration was observed where the number of colonies was proportionally greater relative to the total density of trichomes. Trichodesmium blooms are harmful to shrimp larvae and may lead to plankton community mortality. This study is the first record of neurotoxic blooms in the open waters of the South Atlantic. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Biogeography of top predators - seabirds and cetaceans - along four latitudinal transects in the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Jungblut, Simon; Nachtsheim, Dominik A.; Boos, Karin; Joiris, Claude R.

    2017-07-01

    The distribution, abundance, and species assemblage of top predators - seabirds and cetaceans - can be correlated to water masses as defined by hydrological parameters. In comparison to other oceans, information about the structuring effects of water masses on top predators in the Atlantic Ocean is limited. The present study aims 1) to provide baseline distributional data of top predators for future comparisons, for instance in the course of climate change, and 2) to test how water masses and seasons affect distributional patterns of seabirds and cetaceans in the temperate and tropical Atlantic. During four trans-equatorial expeditions of the RV Polarstern between 2011 and 2014, at-sea observation data of seabirds, cetaceans and other megafauna were collected. Counts of top predators were generally low in the surveyed regions. Statistical analyses for the eight most abundant seabird species and the pooled number of cetaceans revealed water masses and seasons to account for differences in counts and thus also distribution. In most cases, borders between water masses were not very distinct due to gradual changes in surface water properties. Thus, top predator counts were correlated to water masses but, in contrast to polar waters, not strongly linked to borders between water masses. Additional factors, e.g. distance to locally productive areas (upwelling), competition effects, and seabird associations to prey-accumulating subsurface predators may be similarly important in shaping distributional patterns of top predators in the tropical and temperate Atlantic, but could not be specifically tested for here.

  18. ITCZ controls on Late Cretaceous black shale sedimentation in the tropical Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Hofmann, P.; Wagner, T.

    2011-12-01

    This study presents high resolution organic and inorganic proxy records for Coniacian to Santonian black shale on the Demerara Rise (ODP Site 1261) in the western tropical Atlantic off South America. We integrate these records with approximately time equivalent geochemical data from the eastern tropical Atlantic off tropical Africa (ODP Site 959) to extract the underlying relationships of Intertropical Convergence Zone (ITCZ) dynamics and black shale formation in the tropical Cretaceous Atlantic at orbital time scales. The geochemical records from the Demerara Rise show repetitive fluctuations in productivity, ocean redox conditions, and clastic sediment supply consistent with a dynamic paleo-upwelling regime off tropical South America. Upwelling intensity most likely was driven by shifts of the mean annual position of the ITCZ, which connects the large-scale precipitation and wind field patterns of the Hadley cells. Upwelling was strongest off South America and burial of oil-prone organic matter most pronounced when the ITCZ was in its southernmost position, which maximized the impact of NE trade winds on the inner, tropical part of the northern Hadley cell. Geochemical records from the Deep Ivorian Basin (equatorial Atlantic) suggest that source rock formation occurred in phase with regions north of the equator. Off tropical Africa, however, black shale formation was primarily driven by regional rainfall and nutrient export. The results of this study provide a conceptual framework that explains the formation, distribution and quality of petroleum source rocks below the tropical component of the Hadley cells on orbital time scales.

  19. Ocean Surface Layer Response Under Madden-Julian Oscillation Convective Systems in the Equatorial Indian Ocean

    NASA Astrophysics Data System (ADS)

    Pujiana, K.; Moum, J. N.

    2016-02-01

    Extensive surface heat flux, acoustics, and turbulence measurements, from a geostationary ship at 0,80.5E and from moorings at 0,80.5E and 0,90E equipped with moored temperature microstructure profilers [χpod], documented buoyancy and current responses to four Madden-Julian Oscillation (MJO) passages in the central-eastern equatorial Indian Ocean during the fall 2011 - spring 2012 DYNAMO experiment. Each MJO passage was marked with a net air-sea heat flux into the atmosphere, mainly controlled by attenuated shortwave radiation and increased evaporative cooling, and the occurrence of westerly wind bursts which lasted for a couple of days. In response to the prevailing strong eastward wind stress (τx> 0.2 N/m2) and buoyancy loss (Jb0>5x10-7 m2s-3), sea surface temperature dropped by about 0.5°-1.5°C, strong surface-forced mixing occurred (turbulent kinetic energy dissipation rate ɛ>10-6 m2s-3), homogeneous layer within the upper 40-60 m formed, pycnocline descended, and westerly-driven eastward currents accelerated. Although intermittent surface freshening due to rain squalls was evident, entrained subsurface salty water appeared to increase surface salinity by 0.3 - 0.5 psu during MJO passage. The swift 1-1.5 m/s eastward currents (the Yoshida Wyrtki jet), strongest across the upper 90 m and within 2° of the equator, persisted for several weeks and created highly sheared currents below the jet's base inducing amplified shear instability-generated mixing beneath the surface mixed layer. Low Ri (<0.5) and strong turbulent kinetic energy dissipation rate (10-7<ɛ<10-6 m2s-3) characterized the jet's base between 60-90 m. This sustained subsurface vertical mixing attributed to the Yoshida-Wyrkti jet affects the surface mixed layer heat budget and potentially delays the sea surface temperature recovery following the MJO passage.

  20. Control of community growth and export production by upwelled iron in the equatorial Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Coale, Kenneth H.; Fitzwater, Steve E.; Gordon, R. Michael; Johnson, Kenneth S.; Barber, Richard T.

    1996-02-01

    THE 'iron hypothesis'1,2 states that phytoplankton growth and biomass are limited by low concentrations of available iron in large regions of the world's oceans where other plant nutrients are abundant. Such limitation has been demonstrated by experiments in which iron has been added to both enclosed and in situ (un-enclosed) phytoplankton populations2-6. A corollary of the iron hypothesis is that most 'new' iron is supplied by atmospheric deposition7,8, and it has been suggested that changes in the deposition rates of iron-bearing dust have led to changes in biological productivity and, consequently, global climate7. Here we report surface-water measurements in the equatorial Pacific Ocean which show that the main iron source to equatorial waters at 140° W is from upwelling waters. Shipboard in vitro experiments indicate that sub-nanomolar increases in iron concentrations can cause substantial increases in carbon export to deeper waters in this region. These findings demonstrate that equatorial biological production is controlled not solely by atmospheric iron deposition, but also by processes which influence the rate of upwelling and the iron concentration in upwelled water.

  1. Intraseasonal Variability of the Equatorial Indian Ocean Observed from Sea Surface Height, Wind, and Temperature Data

    NASA Technical Reports Server (NTRS)

    Fu, Lee-Lueng

    2007-01-01

    The forcing of the equatorial Indian Ocean by the highly periodic monsoon wind cycle creates many interesting intraseasonal variabilities. The frequency spectrum of the wind stress observations from the European Remote Sensing Satellite scatterometers reveals peaks at the seasonal cycle and its higher harmonics at 180, 120, 90, and 75 days. The observations of sea surface height (SSH) from the Jason and Ocean Topography Experiment (TOPEX)/Poseidon radar altimeters are analyzed to study the ocean's response. The focus of the study is on the intraseasonal periods shorter than the annual period. The semiannual SSH variability is characterized by a basin mode involving Rossby waves and Kelvin waves traveling back and forth in the equatorial Indian Ocean between 10(deg)S and 10(deg)N. However, the interference of these waves with each other masks the appearance of individual Kelvin and Rossby waves, leading to a nodal point (amphidrome) of phase propagation on the equator at the center of the basin. The characteristics of the mode correspond to a resonance of the basin according to theoretical models. The theory also calls for similar modes at 90 and 60 days.

  2. Intraseasonal Variability of the Equatorial Indian Ocean Observed from Sea Surface Height, Wind, and Temperature Data

    NASA Technical Reports Server (NTRS)

    Fu, Lee-Lueng

    2007-01-01

    The forcing of the equatorial Indian Ocean by the highly periodic monsoon wind cycle creates many interesting intraseasonal variabilities. The frequency spectrum of the wind stress observations from the European Remote Sensing Satellite scatterometers reveals peaks at the seasonal cycle and its higher harmonics at 180, 120, 90, and 75 days. The observations of sea surface height (SSH) from the Jason and Ocean Topography Experiment (TOPEX)/Poseidon radar altimeters are analyzed to study the ocean's response. The focus of the study is on the intraseasonal periods shorter than the annual period. The semiannual SSH variability is characterized by a basin mode involving Rossby waves and Kelvin waves traveling back and forth in the equatorial Indian Ocean between 10(deg)S and 10(deg)N. However, the interference of these waves with each other masks the appearance of individual Kelvin and Rossby waves, leading to a nodal point (amphidrome) of phase propagation on the equator at the center of the basin. The characteristics of the mode correspond to a resonance of the basin according to theoretical models. The theory also calls for similar modes at 90 and 60 days.

  3. Summertime phytoplankton blooms and surface cooling in the western south equatorial Indian Ocean

    NASA Astrophysics Data System (ADS)

    Liao, Xiaomei; Du, Yan; Zhan, Haigang; Shi, Ping; Wang, Jia

    2014-11-01

    Chlorophyll-a (Chla) concentration derived from the Sea viewing Wide field of View sensor (SeaWiFS) data (January 1998 to December 2010) shows phytoplankton blooms in the western south equatorial Indian Ocean (WSEIO) during the summer monsoon. The mechanism that sustains the blooms is investigated with the high-resolution Ocean General Circulation Model for the Earth Simulator (OFES) products. The summer blooms in the WSEIO are separated from the coast; they occur in June, reach their maximum in August, and decay in October. With summer monsoon onset, cross-equatorial wind induces open-ocean upwelling in the WSEIO, uplifting the nutricline. The mixed layer heat budget analysis reveals that both thermal forcing and ocean processes are important for the seasonal variations of SST, especially wind-driven entrainment plays a significant role in cooling the WSEIO. These processes cause nutrient enrichment in the surface layer and trigger the phytoplankton blooms. As the summer monsoon develops, the strong wind deepens the mixed layer; the entrainment thus increases the nutrient supply and enhances the bloom. Horizontal advection associated with the Southern Gyre might also be an important process that sustains the bloom. This large clockwise gyre could advect nutrient-rich water along its route, allowing Chla to bloom in a larger area.

  4. An updated anthropogenic CO2 inventory in the Atlantic Ocean

    SciTech Connect

    Lee, K.; Choi, S.-D.; Park, G.-H.; Peng, T.-H.; Key, Robert; Sabine, Chris; Feely, R. A.; Bullister, J.L.; Millero, F. J.; Kozyr, Alexander

    2003-01-01

    This paper presents a comprehensive analysis of the basin-wide inventory of anthropogenic CO2 in the Atlantic Ocean based on high-quality inorganic carbon, alkalinity, chlorofluorocarbon, and nutrient data collected during the World Ocean Circulation Experiment (WOCE) Hydrographic Program, the Joint Global Ocean Flux Study (JGOFS), and the Ocean-Atmosphere Carbon Exchange Study (OACES) surveys of the Atlantic Ocean between 1990 and 1998. Anthropogenic CO2 was separated from the large pool of dissolved inorganic carbon using an extended version of the DC* method originally developed by Gruber et al. [1996]. The extension of the method includes the use of an optimum multiparameter analysis to determine the relative contributions from various source water types to the sample on an isopycnal surface. Total inventories of anthropogenic CO2 in the Atlantic Ocean are highest in the subtropical regions at 20 40, whereas anthropogenic CO2 penetrates the deepest in high-latitude regions (>40N). The deeper penetration at high northern latitudes is largely due to the formation of deep water that feeds the Deep Western Boundary Current, which transports anthropogenic CO2 into the interior. In contrast, waters south of 50S in the Southern Ocean contain little anthropogenic CO2. Analysis of the data collected during the 1990 1998 period yielded a total anthropogenic CO2 inventory of 28.4 4.7 Pg C in the North Atlantic (equator-70N) and of 18.5 3.9 Pg C in the South Atlantic (equator-70S). These estimated basin-wide inventories of anthropogenic CO2 are in good agreement with previous estimates obtained by Gruber [1998], after accounting for the difference in observational periods. Our calculation of the anthropogenic CO2 inventory in the Atlantic Ocean, in conjunction with the inventories calculated previously for the Indian Ocean [Sabine et al., 1999] and for the Pacific Ocean [Sabine et al., 2002], yields a global anthropogenic CO2 inventory of 112 17 Pg C that has accumulated

  5. 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.

  6. Interactions between sea surface temperature over the South Atlantic Ocean and the South Atlantic Convergence Zone

    NASA Astrophysics Data System (ADS)

    Chaves, Rosane Rodrigues; Nobre, Paulo

    2004-02-01

    Interactions between the sea surface temperature (SST) over the South Atlantic Ocean (40°S-Equador) and the South Atlantic Convergence Zone (SACZ) were studied through numerical experiments with an atmospheric general circulation model (AGCM) and an ocean general circulation model (OGCM). The AGCM experiments showed that warm SST anomalies over the South Atlantic tend to intensify the SACZ and shift it northward, while cool SST anomalies over the South Atlantic tend to weaken the SACZ. The OGCM experiments, on the other hand, showed that the intensification of the SACZ contributes to cool the underlying ocean through the reduction of incident shortwave solar radiation, causing the appearance of cold SST anomalies or the weakening of pre-existing warm SST anomalies. The most important finding in this work was the predominance of the cloud/shortwave - SST negative thermodynamic feedback between the atmosphere and the ocean over the southwest tropical Atlantic, this is one order of magnitude larger than the dynamic feedback associated with Ekman pumping. The latter was verified only during strong SACZ events. The results suggest that negative SST anomalies often observed underlying the SACZ represent an ocean response to atmospheric forcing.

  7. Southern Ocean control of silicon stable isotope distribution in the deep Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    de Souza, Gregory F.; Reynolds, Ben C.; Rickli, Jörg; Frank, Martin; Saito, Mak A.; Gerringa, Loes J. A.; Bourdon, Bernard

    2012-06-01

    The fractionation of silicon (Si) stable isotopes by biological activity in the surface ocean makes the stable isotope composition of silicon (δ30Si) dissolved in seawater a sensitive tracer of the oceanic biogeochemical Si cycle. We present a high-precision dataset that characterizes the δ30Si distribution in the deep Atlantic Ocean from Denmark Strait to Drake Passage, documenting strong meridional and smaller, but resolvable, vertical δ30Si gradients. We show that these gradients are related to the two sources of deep and bottom waters in the Atlantic Ocean: waters of North Atlantic and Nordic origin carry a high δ30Si signature of ≥+1.7‰ into the deep Atlantic, while Antarctic Bottom Water transports Si with a low δ30Si value of around +1.2‰. The deep Atlantic δ30Si distribution is thus governed by the quasi-conservative mixing of Si from these two isotopically distinct sources. This disparity in Si isotope composition between the North Atlantic and Southern Ocean is in marked contrast to the homogeneity of the stable nitrogen isotope composition of deep ocean nitrate (δ15N-NO3). We infer that the meridional δ30Si gradient derives from the transport of the high δ30Si signature of Southern Ocean intermediate/mode waters into the North Atlantic by the upper return path of the meridional overturning circulation (MOC). The basin-scale deep Atlantic δ30Si gradient thus owes its existence to the interaction of the physical circulation with biological nutrient uptake at high southern latitudes, which fractionates Si isotopes between the abyssal and intermediate/mode waters formed in the Southern Ocean.

  8. Chloromethane and dichloromethane in the tropical Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Kolusu, Seshagiri Rao; Schlünzen, K. Heinke; Grawe, David; Seifert, Richard

    2017-02-01

    Chloromethane and dichloromethane were measured in the air of marine environment and in seawater during a cruise from the Port of Spain to Rio de Janeiro in the tropical Atlantic Ocean in April and May of 2009. Variation of chloromethane and dichloromethane concentrations was analysed as a function of latitude. There is no correlation observed between chloromethane and dichloromethane concentrations in the seawater suggest that they may not have a common oceanic source. In addition, a relation of concentrations, fluxes and sea surface temperature were studied to determine a dependency of concentrations and fluxes on sea surface temperature. Sea surface temperature does not show any significant effect on dichloromethane concentrations in surface seawater. Chloromethane and dichloromethane are supersaturated in the seawater during the cruise. This implies that the tropical Atlantic Ocean emits chloromethane and dichloromethane into the atmosphere. The tropical Atlantic Ocean mean fluxes of chloromethane and dichloromethane during the cruise were 150 nmol m-2 d-1 and 81 nmol m-2 d-1, respectively. The backward trajectory analysis revealed that the tropical Atlantic Ocean and African coast were primary and secondary source regions for chloromethane and dichloromethane respectively, during the Meteor cruise.

  9. Assessing the impact of various wind forcing on INCOIS-GODAS simulated ocean currents in the equatorial Indian Ocean

    NASA Astrophysics Data System (ADS)

    Sivareddy, Sanikommu; Ravichandran, Muthalagu; Girishkumar, Madathil Sivasankaran; Prasad, Koneru Venkata Siva Rama

    2015-09-01

    The Global Ocean Data Assimilation System configured at Indian National Centre for Ocean Information Services (INCOIS-GODAS) has been forced with satellite-based QuikSCAT gridded winds (QSCAT) to obtain accurate operational ocean analysis, particularly ocean currents, as compared to the default National Centers for Environmental Prediction-Reanalysis 2 (NCEP-R2) wind forcing in the tropical Indian Ocean (TIO). However, after termination of QuikSCAT mission in November 2009, an alternate wind forcing was required for providing operational ocean analysis. The present study examines the suitability of an Advanced Scatterometer (ASCAT)-based daily gridded wind product (DASCAT) for the INCOIS-GODAS. Experiments were performed by forcing INCOIS-GODAS with three different momentum fluxes derived from QSCAT, DASCAT, and NCEP-R2 wind products. Simulated ocean currents from these experiments are validated with respect to in situ current measurements from Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction (RAMA) buoys. Results suggested that the quality of simulated ocean currents from the daily DASCAT forcing is on par with the QSCAT forcing in the TIO, except for the equatorial Indian Ocean (EIO). Although QSCAT-forced current simulations are slightly better than DASCAT-forced simulations, both QSCAT and DASCAT provide a much better result than NCEP-R2. Our analysis shows that the better simulations of currents over the EIO, with the QSCAT forcing compared to DASCAT forcing, can be attributed to the smoothening of the wind field in the DASCAT compared to QSCAT. The impact of the error in the DASCAT on ocean current analysis is, however, limited to local scales and upper 100 m of water column only. Thus, our study demonstrated that, in the absence of QSCAT, DASCAT is a better alternative for INCOIS-GODAS ocean analysis than the NCEP-R2.

  10. In situ interactions between photosynthetic picoeukaryotes and bacterioplankton in the Atlantic Ocean: evidence for mixotrophy.

    PubMed

    Hartmann, Manuela; Zubkov, Mikhail V; Scanlan, Dave J; Lepère, Cécile

    2013-12-01

    Heterotrophic bacterioplankton, cyanobacteria and phototrophic picoeukaryotes (< 5 μm in size) numerically dominate planktonic oceanic communities. While feeding on bacterioplankton is often attributed to aplastidic protists, recent evidence suggests that phototrophic picoeukaryotes could be important bacterivores. Here, we present direct visual evidence from the surface mixed layer of the Atlantic Ocean that bacterioplankton are internalized by phototrophic picoeukaryotes. In situ interactions of phototrophic picoeukaryotes and bacterioplankton (specifically Prochlorococcus cyanobacteria and the SAR11 clade) were investigated using a combination of flow cytometric cell sorting and dual tyramide signal amplification fluorescence in situ hybridization. Using this method, we observed plastidic Prymnesiophyceae and Chrysophyceae cells containing Prochlorococcus, and to a lesser extent SAR11 cells. These microscopic observations of in situ microbial trophic interactions demonstrate the frequency and likely selectivity of phototrophic picoeukaryote bacterivory in the surface mixed layer of both the North and South Atlantic subtropical gyres and adjacent equatorial region, broadening our views on the ecological role of the smallest oceanic plastidic protists.

  11. Coherent heat patterns revealed by unsupervised classification of Argo temperature profiles in the North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Maze, Guillaume; Mercier, Herlé; Fablet, Ronan; Tandeo, Pierre; Lopez Radcenco, Manuel; Lenca, Philippe; Feucher, Charlène; Le Goff, Clément

    2017-02-01

    A quantitative understanding of the integrated ocean heat content depends on our ability to determine how heat is distributed in the ocean and identify the associated coherent patterns. This study demonstrates how this can be achieved using unsupervised classification of Argo temperature profiles. The classification method used is a Gaussian Mixture Model (GMM) that decomposes the Probability Density Function of a dataset into a weighted sum of Gaussian modes. It is determined that the North Atlantic Argo dataset of temperature profiles contains 8 groups of vertically coherent heat patterns, or classes. Each of the temperature profile classes reveals unique and physically coherent heat distributions along the vertical axis. A key result of this study is that, when mapped in space, each of the 8 classes is found to define an oceanic region, even if no spatial information was used in the model determination. The classification result is independent of the location and time of the ARGO profiles. Two classes show cold anomalies throughout the water column with amplitude decreasing with depth. They are found to be localized in the subpolar gyre and along the poleward flank of the Gulf Stream and North Atlantic Current (NAC). One class has nearly zero anomalies and a large spread throughout the water column. It is found mostly along the NAC. One class has warm anomalies near the surface (50 m) and cold ones below 200 m. It is found in the tropical/equatorial region. The remaining four classes have warm anomalies throughout the water column, one without depth dependance (in the southeastern part of the subtropical gyre), the other three with clear maximums at different depths (100 m, 400 m and 1000 m). These are found along the southern flank of the North Equatorial Current, the western part of the subtropical gyre and over the West European Basin. These results are robust to both the seasonal variability and to method parameters such as the size of the analyzed domain.

  12. Significance of ODP results on deepwater hydrocarbon exploration Eastern equatorial Atlantic region

    NASA Astrophysics Data System (ADS)

    Katz, Barry Jay

    2006-11-01

    Scientific ocean drilling has provided access to samples of potential hydrocarbon source rocks in a number of deepwater regions around the globe. The samples are often well constrained stratigraphically and normally free from organic drilling fluid contamination. The focus of this study is the results obtained on one of the Ocean Drilling Program's (ODP) legs - Leg 159, which was located along the Equatorial portion of the West African margin, a region of considerable hydrocarbon exploration interest. Four drilling sites were included in Leg 159 along the continental margins of Côte d'Ivorie and Ghana. Drilling at these sites recovered sediments of Albian to Pleistocene age. Prior studies revealed the presence of a number of organic-rich zones capable of yielding significant quantities of hydrocarbons within both the Cretaceous and Tertiary sections. These intervals could act as hydrocarbon sources, if suitable maturity levels were obtained. Both oil and gas would be expected as their primary products. A shore-based study which focused on Site 959 and to a lesser degree Site 962 provided an opportunity to expand upon the original dataset and to further characterize the organic matter. Detailed characterization of the bitumen fractions from Site 959, provided not only information on the geochemical character of these specific sediments, but permitted them to be placed into a more regional context by comparing them to oils from the Equatorial portion of the West African margin. These data reveal a similarity, but not necessarily a genetic relationship, between the Cretaceous sediments and the majority of the Côte d'Ivoire oils. The Paleogene extracts display similar geochemical attributes as the deepwater oils from the Niger Delta. Although this study is not attempting to establish a definitive correlation, the data suggest a Tertiary source rock system for the deepwater Niger Delta, where deposition occurred under oxic to sub-oxic conditions. This contrasts with

  13. 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.

  14. The Atlantic Multidecadal Oscillation without a role for ocean circulation

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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.

  15. 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...

  16. 33 CFR 110.188 - Atlantic Ocean off Miami and Miami Beach, 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 Miami and... HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Anchorage Grounds § 110.188 Atlantic Ocean off Miami and... in cases of great emergency, no vessel shall be anchored in the Atlantic Ocean in the vicinity of the...

  17. 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...

  18. 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...

  19. 33 CFR 110.188 - Atlantic Ocean off Miami and Miami Beach, 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 Miami and... HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Anchorage Grounds § 110.188 Atlantic Ocean off Miami and... in cases of great emergency, no vessel shall be anchored in the Atlantic Ocean in the vicinity of the...

  20. 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...

  1. 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...

  2. 33 CFR 110.188 - Atlantic Ocean off Miami and Miami Beach, 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 Miami and... HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Anchorage Grounds § 110.188 Atlantic Ocean off Miami and... in cases of great emergency, no vessel shall be anchored in the Atlantic Ocean in the vicinity of the...

  3. 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...

  4. 33 CFR 110.188 - Atlantic Ocean off Miami and Miami Beach, 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 Miami and... HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Anchorage Grounds § 110.188 Atlantic Ocean off Miami and... in cases of great emergency, no vessel shall be anchored in the Atlantic Ocean in the vicinity of the...

  5. 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...

  6. 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...

  7. 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...

  8. 33 CFR 110.188 - Atlantic Ocean off Miami and Miami Beach, 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 Miami and... HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Anchorage Grounds § 110.188 Atlantic Ocean off Miami and... in cases of great emergency, no vessel shall be anchored in the Atlantic Ocean in the vicinity of the...

  9. 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...

  10. Observations of Equatorial Kelvin Waves and their Convective Coupling with the Atmosphere/Ocean Surface Layer

    NASA Astrophysics Data System (ADS)

    Conry, Patrick; Fernando, H. J. S.; Leo, Laura; Blomquist, Byron; Amelie, Vincent; Lalande, Nelson; Creegan, Ed; Hocut, Chris; MacCall, Ben; Wang, Yansen; Jinadasa, S. U. P.; Wang, Chien; Yeo, Lik-Khian

    2016-11-01

    Intraseasonal disturbances with their genesis in the equatorial Indian Ocean (IO) are an important component of global climate. The disturbances, which include Madden-Julian Oscillation and equatorial Kelvin and Rossby waves in the atmosphere and ocean, carry energy which affects El Niño, cyclogenesis, and monsoons. A recent field experiment in IO (ASIRI-RAWI) observed disturbances at three sites across IO with arrays of instruments probing from surface layer to lower stratosphere. During the field campaign the most pronounced planetary-scale disturbances were Kelvin waves in tropical tropopause layer. In Seychelles, quasi-biweekly westerly wind bursts were documented and linked to the Kelvin waves aloft, which breakdown in the upper troposphere due to internal shear instabilities. Convective coupling between waves' phase in upper troposphere and surface initiates rapid (turbulent) vertical transport and resultant wind bursts at surface. Such phenomena reveal linkages between planetary-scale waves and small-scale turbulence in the surface layer that can affect air-sea property exchanges and should be parameterized in atmosphere-ocean general circulation models. Funded by ONR Grants N00014-14-1-0279 and N00014-13-1-0199.

  11. Particle size traces modern Saharan dust transport and deposition across the equatorial North Atlantic

    NASA Astrophysics Data System (ADS)

    van der Does, Michèlle; Korte, Laura F.; Munday, Chris I.; Brummer, Geert-Jan A.; Stuut, Jan-Berend W.

    2016-11-01

    Mineral dust has a large impact on regional and global climate, depending on its particle size. Especially in the Atlantic Ocean downwind of the Sahara, the largest dust source on earth, the effects can be substantial but are poorly understood. This study focuses on seasonal and spatial variations in particle size of Saharan dust deposition across the Atlantic Ocean, using an array of submarine sediment traps moored along a transect at 12° N. We show that the particle size decreases downwind with increased distance from the Saharan source, due to higher gravitational settling velocities of coarse particles in the atmosphere. Modal grain sizes vary between 4 and 32 µm throughout the different seasons and at five locations along the transect. This is much coarser than previously suggested and incorporated into climate models. In addition, seasonal changes are prominent, with coarser dust in summer and finer dust in winter and spring. Such seasonal changes are caused by transport at higher altitudes and at greater wind velocities during summer than in winter. Also, the latitudinal migration of the dust cloud, associated with the Intertropical Convergence Zone, causes seasonal differences in deposition as the summer dust cloud is located more to the north and more directly above the sampled transect. Furthermore, increased precipitation and more frequent dust storms in summer coincide with coarser dust deposition. Our findings contribute to understanding Saharan dust transport and deposition relevant for the interpretation of sedimentary records for climate reconstructions, as well as for global and regional models for improved prediction of future climate.

  12. Variability of zonal currents in the eastern equatorial Indian Ocean on seasonal to interannual time scales

    NASA Astrophysics Data System (ADS)

    Nyadjro, Ebenezer S.; McPhaden, Michael J.

    2014-11-01

    This study examines equatorial zonal current variations in the upper layers of eastern Indian Ocean in relation to variations in the Indian Ocean Dipole (IOD). The analysis utilizes data from the Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction (RAMA) and the European Centre for Medium-Range Weather Forecasts-Ocean Reanalysis System 4 (ECMWF-ORAS4). Surface currents are characterized by semiannual eastward flowing Wyrtki jets along the equator in boreal spring and fall, forced by westerly monsoon transition winds. The fall jet intensifies during negative IOD (NIOD) events when westerlies are anomalously strong but significantly weakens during positive IOD (PIOD) events when westerlies are anomalously weak. As zonal wind stress weakens during PIOD events, sea surface height becomes unusually low in the eastern basin and high in the west, setting up an anomalous pressure force that drives increased eastward transport in the thermocline. Opposite tendencies are evident during NIOD events in response to intensified equatorial westerlies. Current transport adjustments to anomalous zonal wind forcing during IOD events extend into the following year, consistent with the cycling of equatorial wave energy around the basin. A surface layer mass budget calculation for the eastern sea surface temperature (SST) pole of the IOD indicates upwelling of ˜2.9±0.7 Sv during normal periods, increasing by 40-50% during PIOD events and reducing effectively to zero during NIOD events. IOD-related variations in Wyrtki jet and thermocline transports are major influences on these upwelling rates and associated water mass transformations, which vary consistently with SST changes.

  13. 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.

  14. Impact of model resolution on biogeochemical tracers concentration in the tropical Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Duteil, Olaf; Boening, Claus; Oschlies, Andreas

    2014-05-01

    Representing correctly the distribution of biogeochemical tracers in the interior ocean, such as oxygen or phosphate, is hampered by large biases in the representation of circulation in the coarse resolution models. Here we assess the oxygen and phosphate budget in two configurations of a coupled circulation biogeochemical model (NEMO - NPZD), focusing on the Atlantic Ocean. These two configurations have been integrated using realistic atmospheric forcings for the period 1948-2007. While a coarse (0.5°) configuration displays the common bias of too low oxygen associated with too high phosphate concentration, particularly at intermediate depth in the eastern side of the basin, the values are closer to the observations in an eddying (0.1°) configuration. The improvement in the representation of oxygen and phosphate is traced to a stronger transport by a more realistic representation of the equatorial and off-equatorial undercurrents. The biogeochemical fluxes are less sensitive to the current strength as the phytoplankton growth is mainly limited by the available light in the two configurations. This study emphasizes the need of high resolution models to tackle coupled biogeochemical problematics, such as the extension of oxygen minimum zones or variability in the eastern boundary upwelling system productivity.

  15. Meso-Cenozoic Source-to-Sink analysis of the African margin of the Equatorial Atlantic

    NASA Astrophysics Data System (ADS)

    Chardon, Dominique; Rouby, Delphine; Huyghe, Damien; Ye, Jing; Guillocheau, François; Robin, Cécile; Dall'Asta, Massimo; Brown, Roderick; Webster, David

    2015-04-01

    The Transform Source to Sink Project (TS2P) objective is to link the evolution of the offshore sedimentary basins of the African margin of the Equatorial Atlantic and their source areas on the West African Craton. The margin consists in alternating transform and oblique margin portions from Guinea, in the West, to Nigeria, in the East. Such a longitudinal structural variability is associated with variation in the margin width, continental geology and relief, drainage networks and subsidence/accumulation patterns that we analyzed using offshore seismic data and onshore geology and geomorphology. We compare syn- to post rift offshore geometry and long-term stratigraphic history of each of the margin segments. Transform faults appear to play a major role in shaping Early Cretaceous syn-rift basin architectures. Immediate post-rift Late Cretaceous sedimentary wedges record a transgression and are affected by the reactivation of some of transform faults. We produced A new type of inland paleogeographic maps for key periods since the end of the Triassic, allowing delineation of intracratonic basins having accumulated material issued from erosion of the marginal upwarps that have grown since break-up along the margin. We use offshore and onshore basin analysis to estimate sediment accumulation and integrate it in a source-to-sink analysis where Mesozoic onshore denudation will be estimated by low-temperature thermochronology. Cenozoic erosion and drainage history of the continental domain have been reconstructed from the spatial analysis of dated and regionally correlated geomorphic markers. The stationary drainage configuration of the onshore domain since 30 Ma offers the opportunity to correlate the detailed onshore morphoclimatic record based on the sequence of lateritic paleolandsurfaces to offshore stratigraphy, eustasy and global climatic proxies since the Oligocene. Within this framework, we simulate quantitative solute / solid erosional fluxes based on the

  16. Performance of Mixed Layer Models in Simulating SST in the Equatorial Pacific Ocean

    DTIC Science & Technology

    2008-02-23

    Perfomance of mixed layer models in simulating SST in the equatorial Pacific Ocean, J. Geophys. Res., 113, C02020, doi:10.1029/2007JC004250. 1. Introduction...overall model run time is approximately the same with KPP and GISS, but is 1.5 times longer with MY (primarily because of its additional prognostic fields...150’W) uses monthly SST anomalies based on a difference between the normalized Darwin and Tahiti SLP 5-month running mean, and the threshold value

  17. Riverine influence on ocean color in the equatorial South China Sea

    NASA Astrophysics Data System (ADS)

    Sun, Che

    2017-07-01

    Analysis of SeaWiFS data off Northwest Borneo reveals coastal chlorophyll bloom extending more than 200 km to deep South China Sea during winter. A combination of remote sensing products is used to untangle its statistical relation with various forcing factors. River discharge rate is estimated from satellite measurements of land rainfall, and surface chlorophyll over the middle shelf is shown to vary with river discharge and lag by one month. Strong (weak) chlorophyll blooms tend to occur in La Niña (El Niño) years. The study provides evidence that river runoff from maritime continent has major influence on equatorial ocean color.

  18. Suspended particle organic composition and cycling in surface and midwaters of the equatorial Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Sheridan, C. C.; Lee, C.; Wakeham, S. G.; Bishop, J. K. B.

    2002-11-01

    In this study we relate spatial and temporal variation in the organic composition of suspended particles to current conceptual models of open-ocean particle cycling. Suspended particles in surface (0-200 m) and midwaters (200-1000 m) of the equatorial Pacific Ocean were collected during the 1992 US JGOFS Equatorial Pacific (EqPac) program. Samples collected during El Niño (Survey I) and normal conditions (Survey II) were analyzed for pigment, amino acid, fatty acid, and neutral lipid concentrations and compositions. Principal Components Analysis (PCA) and other statistical methods were used to assess changes in particulate organic composition between Surveys I and II, over 24° of latitude, from 15 to 850 m depth, and to compare our compositional data with previously published data from EqPac sinking particles. These analyses indicated that surface suspended particles (0-200 m) were similar in composition to surface ocean phytoplankton and were less degraded than particles sinking out of the euphotic zone (105 m). The organic composition of suspended particles in surface waters varied with latitudinal and El-Niño-induced changes in phytoplankton assemblages. Midwater suspended particles (200-1000 m) contained labile phytodetrital material derived from particles exiting the euphotic zone (105 m). However, labile organic constituents of midwater suspended particles were increasingly degraded by microbes or consumed by midwater metazoans with depth. The increase in degradation state observed for midwater suspended particles may also have been caused by dilution of deeper (450-850 m) suspended particle pools with more refractory material originating from fast-sinking particles, e.g., fecal pellets. However, the mechanism controlling midwater particle degradation state varied with flux regime; dilution of midwater suspended particles dominated only in the higher flux regime found at equatorial latitudes (5°N-5°S) during Survey II (normal conditions). In summary, it

  19. Detecting anthropogenic carbon dioxide uptake and ocean acidification in the North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Bates, N. R.; Best, M. H. P.; Neely, K.; Garley, R.; Dickson, A. G.; Johnson, R. J.

    2012-01-01

    Fossil fuel use, cement manufacture and land-use changes are the primary sources of anthropogenic carbon dioxide (CO2) to the atmosphere, with the ocean absorbing 30 %. Ocean uptake and chemical equilibration of anthropogenic CO2with seawater results in a gradual reduction in seawater pH and saturation states (Ω) for calcium carbonate (CaCO3) minerals in a process termed ocean acidification. Assessing the present and future impact of ocean acidification on marine ecosystems requires detection of the multi-decadal rate of change across ocean basins and at ocean time-series sites. Here, we show the longest continuous record of ocean CO2 changes and ocean acidification in the North Atlantic subtropical gyre near Bermuda from 1983-2011. Dissolved inorganic carbon (DIC) and partial pressure of CO2 (pCO2) increased in surface seawater by ~40 μmol kg-1 and ~50 μatm (~20 %), respectively. Increasing Revelle factor (β) values imply that the capacity of North Atlantic surface waters to absorb CO2 has also diminished. As indicators of ocean acidification, seawater pH decreased by ~0.05 (0.0017 yr-1) and Ω values by ~7-8 %. Such data provide critically needed multi-decadal information for assessing the North Atlantic Ocean CO2sink and the pH changes that determine marine ecosystem responses to ocean acidification.

  20. Detecting anthropogenic carbon dioxide uptake and ocean acidification in the North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Bates, N. R.; Best, M. H. P.; Neely, K.; Garley, R.; Dickson, A. G.; Johnson, R. J.

    2012-07-01

    Fossil fuel use, cement manufacture and land-use changes are the primary sources of anthropogenic carbon dioxide (CO2) to the atmosphere, with the ocean absorbing approximately 30% (Sabine et al., 2004). Ocean uptake and chemical equilibration of anthropogenic CO2 with seawater results in a gradual reduction in seawater pH and saturation states (Ω) for calcium carbonate (CaCO3) minerals in a process termed ocean acidification. Assessing the present and future impact of ocean acidification on marine ecosystems requires detection of the multi-decadal rate of change across ocean basins and at ocean time-series sites. Here, we show the longest continuous record of ocean CO2 changes and ocean acidification in the North Atlantic subtropical gyre near Bermuda from 1983-2011. Dissolved inorganic carbon (DIC) and partial pressure of CO2 (pCO2) increased in surface seawater by ~40 μmol kg-1 and ~50 μatm (~20%), respectively. Increasing Revelle factor (β) values imply that the capacity of North Atlantic surface waters to absorb CO2 has also diminished. As indicators of ocean acidification, seawater pH decreased by ~0.05 (0.0017 yr-1) and ω values by ~7-8%. Such data provide critically needed multi-decadal information for assessing the North Atlantic Ocean CO2 sink and the pH changes that determine marine ecosystem responses to ocean acidification.

  1. Long-term Paleomagnetic Secular Variation and Excursions from the western Equatorial Pacific Ocean (MIS2-4)

    NASA Astrophysics Data System (ADS)

    Lund, Steve; Schwartz, Martha; Stott, Lowell

    2017-01-01

    SUMMARYNew paleomagnetic results are presented for the Pleistocene (MIS2-4) portion of deep-sea core MD98-2181 (MD81; Devao Gulf, Philippine Islands). MD81 is the highest resolution (˜50 cm/ky) PSV record for ˜12-70 ka ever recovered from <span class="hlt">Equatorial</span> latitudes (±15°). Magnetic studies indicate that MD81 has a stable natural remanence (NRM) with directional uncertainties (MAD angles) typically less than 3°. We have also recovered a relative paleointensity estimate from these sediments based on normalization to SIRMs. We have correlated our relative paleointensity record with high-resolution relative paleointensity records from the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> (Lund et al., 2001a, b). The MD81 ages are always within ± 500 years of the North <span class="hlt">Atlantic</span> records over the entire core. We also correlate our PSV record with another published PSV record from Indonesia (MD34; Blanchet et al., 2006). We are able to correlate 25 inclination features, 25 declination features, and 24 relative paleointensity features between MD81 and MD34. We identify three intervals of `anomalous' directions in the cores (based on > 2σ deviation from mean directions). One of these intervals contains true excursional directions and is dated to ˜40.5 ka. We associate this interval with the Laschamp Excursion (e.g., Bonhommet and Zahringer, 1969; Lund et al, 2005). We also note two other intervals that have anomalous directions, but no true excursional directions. These intervals occur around ˜34.5 ka and ˜61.5 ka and we associate them with the Mono Lake Excursion (˜33.5-34.5 ka) in western USA (e.g., Liddicoat and Coe, 1979) and the Norwegian-Greenland Sea Excursion (˜61 ± 2 ka) in the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> (e.g., Nowaczyk et al., 1994). We view our `anomalous' PSV in the three intervals to be truly anomalous even though most directions are not truly excursional. We think that it is time to reconsider the definition of what is `anomalous' PSV or excursions. To do that we need good</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoJI.209..587L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoJI.209..587L"><span>Long-term palaeomagnetic secular variation and excursions from the western <span class="hlt">Equatorial</span> Pacific <span class="hlt">Ocean</span> (MIS2-4)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lund, Steve; Schwartz, Martha; Stott, Lowell</p> <p>2017-05-01</p> <p>New palaeomagnetic results are presented for the Pleistocene (MIS2-4) portion of deep-sea core MD98-2181 (MD81; Devao Gulf, Philippine Islands). MD81 is the highest resolution (∼50 cm ky-1) palaeomagnetic secular variation (PSV) record for ∼12-70 ka ever recovered from <span class="hlt">equatorial</span> latitudes (±15°). Magnetic studies indicate that MD81 has a stable natural remanence with directional uncertainties (MAD angles) typically less than 3°. We have also recovered a relative palaeointensity estimate from these sediments based on normalization to isothermal remanence. We have correlated our relative palaeointensity record with high-resolution relative palaeointensity records from the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>. The MD81 ages are always within ±500 yr of the North <span class="hlt">Atlantic</span> records over the entire core. We also correlate our PSV record with another published PSV record from Indonesia (MD34). We are able to correlate 25 inclination features, 25 declination features and 24 relative palaeointensity features between MD81 and MD34. We identify three intervals of 'anomalous' directions in the cores (based on >2σ deviation from mean directions). One of these intervals contains true excursional directions and is dated to ∼40.5 ka. We associate this interval with the Laschamp Excursion. We also note two other intervals that have anomalous directions, but no true excursional directions. These intervals occur around ∼34.5 and ∼61.5 ka and we associate them with the Mono Lake Excursion (∼33.5-34.5 ka) in western USA and the Norwegian-Greenland Sea Excursion (∼61 ± 2 ka) in the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>. We view our 'anomalous' PSV in the three intervals to be truly anomalous even though most directions are not truly excursional. We think that it is time to reconsider the definition of what is 'anomalous' PSV or excursions. To do that we need good-quality PSV records from several regions that have reproducible records of normal PSV, excursional waveforms and relative palaeointensity</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-s62-06606.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-s62-06606.html"><span>Cloud formation over Western <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> north of South America</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>1962-10-03</p> <p>S62-06606 (3 Oct. 1962) --- Cloud formation over Western <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-as4-01-410.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-as4-01-410.html"><span>Brazil, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Africa, Sahara & Antarctica seen from Apollo 4</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>1967-11-09</p> <p>AS04-01-410 (9 Nov. 1967) --- Coastal Brazil, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10576732','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10576732"><span>Eight centuries of north <span class="hlt">atlantic</span> <span class="hlt">ocean</span> atmosphere variability</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Black; Peterson; Overpeck; Kaplan; Evans; Kashgarian</p> <p>1999-11-26</p> <p>Climate in the tropical North <span class="hlt">Atlantic</span> is controlled largely by variations in the strength of the trade winds, the position of the Intertropical Convergence Zone, and sea surface temperatures. A high-resolution study of Caribbean sediments provides a subdecadally resolved record of tropical upwelling and trade wind variability spanning the past 825 years. These results confirm the importance of a decadal (12- to 13-year) mode of <span class="hlt">Atlantic</span> variability believed to be driven by coupled tropical <span class="hlt">ocean</span>-atmosphere dynamics. Although a well-defined interdecadal mode of variability does not appear to be characteristic of the tropical <span class="hlt">Atlantic</span>, there is evidence that century-scale variability is substantial. The tropical <span class="hlt">Atlantic</span> may also have been involved in a major shift in Northern Hemisphere climate variability that took place about 700 years ago.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUSMOS51A..04K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUSMOS51A..04K"><span>SST Simulations From HYCOM in the <span class="hlt">Equatorial</span> Pacific <span class="hlt">Ocean</span> During ENSO Events Since 1990</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kara, A.; Wallcraft, A.; Hurlburt, H.</p> <p>2005-05-01</p> <p>A 0.72 degree HYbrid Coordinate <span class="hlt">Ocean</span> Model (HYCOM) is set up for the <span class="hlt">Equatorial</span> Pacific and used for predictions of sea surface temperature durin El Nino and La Nina events from 1990 to 2003. The model domain spans 30N-30S in latitude and 70W to 110E in longitude, and the latitudinal resolution is increased to 0.36 degrees near the equator to improve model's <span class="hlt">equatorial</span> dynamics. Model simulations are performed using high resolution (6 hourly) atmospheric forcing from European Centre for Medium-Range Weather Forecasts~(ECMWF). Model simulations include no assimilation of any SST data, and there is no relaxation to any SST climatology. Performance of HYCOM in predicting daily SST is examined using five different mixed layer models: (1) K--Profile Parameterization (KPP), (2) Goddard Institute for Space Studies (GISS) model, (3) Mellor-Yamada 2.5 turbulence closure (MY2.5), (4) Kraus-Turner (KT) model, and (5) Price-Weller-Pinkel (PWP) model. SST simulations from HYCOM are validated against those from moored buoy observations in the <span class="hlt">equatorial</span> Pacific using various statistical metrics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010ESSD....2..177P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010ESSD....2..177P"><span>CARINA TCO2 data in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pierrot, D.; Brown, P.; van Heuven, S.; Tanhua, T.; Schuster, U.; Wanninkhof, R.; Key, R. M.</p> <p>2010-07-01</p> <p>Water column data of carbon and carbon-relevant hydrographic and hydrochemical parameters from 188 cruises in the Arctic Mediterranean Seas, <span class="hlt">Atlantic</span> and Southern <span class="hlt">Ocean</span> have been retrieved and merged in a new data base: the CARINA (CARbon IN the <span class="hlt">Atlantic</span>) Project. These data have gone through rigorous quality control (QC) procedures so as to improve the quality and consistency of the data as much as possible. 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 tentatively 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 Mediterranean Seas, <span class="hlt">Atlantic</span> and Southern <span class="hlt">Ocean</span>). Ninety-eight cruises were conducted in the "<span class="hlt">Atlantic</span>" 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 <span class="hlt">Atlantic</span>. 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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> 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 <span class="hlt">oceanic</span> carbon inventories, uptake rates and model validation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010ESSDD...3....1P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010ESSDD...3....1P"><span>CARINA TCO2 data in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pierrot, D.; Brown, P.; van Heuven, S.; Tanhua, T.; Schuster, U.; Wanninkhof, R.; Key, R. M.</p> <p>2010-01-01</p> <p>Water column data of carbon and carbon-relevant hydrographic and hydrochemical parameters from 188 cruises in the Arctic, <span class="hlt">Atlantic</span> and Southern <span class="hlt">Ocean</span> have been retrieved and merged in a new data base: the CARINA (CARbon IN the <span class="hlt">Atlantic</span>) 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, <span class="hlt">Atlantic</span> and Southern <span class="hlt">Ocean</span>). Ninety-eight cruises were conducted in the "<span class="hlt">Atlantic</span>" 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 <span class="hlt">Atlantic</span>. 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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> 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 <span class="hlt">oceanic</span> carbon inventories, uptake rates and model validation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016OcMod.104..143T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016OcMod.104..143T"><span>North and <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span> circulation in the CORE-II hindcast simulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tseng, Yu-heng; Lin, Hongyang; Chen, Han-ching; Thompson, Keith; Bentsen, Mats; Böning, Claus W.; Bozec, Alexandra; Cassou, Christophe; Chassignet, Eric; Chow, Chun Hoe; Danabasoglu, Gokhan; Danilov, Sergey; Farneti, Riccardo; Fogli, Pier Giuseppe; Fujii, Yosuke; Griffies, Stephen M.; Ilicak, Mehmet; Jung, Thomas; Masina, Simona; Navarra, Antonio; Patara, Lavinia; Samuels, Bonita L.; Scheinert, Markus; Sidorenko, Dmitry; Sui, Chung-Hsiung; Tsujino, Hiroyuki; Valcke, Sophie; Voldoire, Aurore; Wang, Qiang; Yeager, Steve G.</p> <p>2016-08-01</p> <p>We evaluate the mean circulation patterns, water mass distributions, and tropical dynamics of the North and <span class="hlt">Equatorial</span> Pacific <span class="hlt">Ocean</span> based on a suite of global <span class="hlt">ocean</span>-sea ice simulations driven by the CORE-II atmospheric forcing from 1963-2007. The first three moments (mean, standard deviation and skewness) of sea surface height and surface temperature variability are assessed against observations. Large discrepancies are found in the variance and skewness of sea surface height and in the skewness of sea surface temperature. Comparing with the observation, most models underestimate the Kuroshio transport in the Asian Marginal seas due to the missing influence of the unresolved western boundary current and meso-scale eddies. In terms of the Mixed Layer Depths (MLDs) in the North Pacific, the two observed maxima associated with Subtropical Mode Water and Central Mode Water formation coalesce into a large pool of deep MLDs in all participating models, but another local maximum associated with the formation of Eastern Subtropical Mode Water can be found in all models with different magnitudes. The main model bias of deep MLDs results from excessive Subtropical Mode Water formation due to inaccurate representation of the Kuroshio separation and of the associated excessively warm and salty Kuroshio water. Further water mass analysis shows that the North Pacific Intermediate Water can penetrate southward in most models, but its distribution greatly varies among models depending not only on grid resolution and vertical coordinate but also on the model dynamics. All simulations show overall similar large scale tropical current system, but with differences in the structures of the <span class="hlt">Equatorial</span> Undercurrent. We also confirm the key role of the meridional gradient of the wind stress curl in driving the <span class="hlt">equatorial</span> transport, leading to a generally weak North <span class="hlt">Equatorial</span> Counter Current in all models due to inaccurate CORE-II <span class="hlt">equatorial</span> wind fields. Most models show a larger</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017E%26PSL.458..327H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017E%26PSL.458..327H"><span>Reconstruction of east-west deep water exchange in the low latitude <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> over the past 25,000 years</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Howe, Jacob N. W.; Piotrowski, Alexander M.; Hu, Rong; Bory, Aloys</p> <p>2017-01-01</p> <p>Radiogenic neodymium isotopes have been used as a water mass mixing proxy to investigate past changes in <span class="hlt">ocean</span> circulation. Here we present a new depth transect of deglacial neodymium isotope records measured on uncleaned planktic foraminifera from five cores spanning from 3300 to 4900 m on the Mauritanian margin, in the tropical eastern <span class="hlt">Atlantic</span> as well as an additional record from 4000 m on the Ceara Rise in the <span class="hlt">equatorial</span> western <span class="hlt">Atlantic</span>. Despite being located under the Saharan dust plume, the eastern <span class="hlt">Atlantic</span> records differ from the composition of detrital inputs through time and exhibit similar values to the western <span class="hlt">Atlantic</span> foraminiferal Nd across the deglaciation. Therefore we interpret the foraminiferal values as recording deep water Nd isotope changes. All six cores shift to less radiogenic values across the deglaciation, indicating that they were bathed by a lower proportion of North <span class="hlt">Atlantic</span> Deep Water during the Last Glacial Maximum (LGM) relative to the Holocene. The eastern <span class="hlt">Atlantic</span> records also show that a neodymium isotope gradient was present during the LGM and during the deglaciation, with more radiogenic values observed at the deepest sites. A homogeneous water mass observed below 3750 m in the deepest eastern <span class="hlt">Atlantic</span> during the LGM is attributed to the mixing of deep water by rough topography as it passes from the western <span class="hlt">Atlantic</span> through the fracture zones in the Mid-<span class="hlt">Atlantic</span> Ridge. This implies that during the LGM the low latitude deep eastern <span class="hlt">Atlantic</span> was ventilated from the western <span class="hlt">Atlantic</span> via advection through fracture zones in the same manner as occurs in the modern <span class="hlt">ocean</span>. Comparison with carbon isotopes indicates there was more respired carbon in the deep eastern than deep western <span class="hlt">Atlantic</span> during the LGM, as is also seen in the modern <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015Ocgy...55..884L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015Ocgy...55..884L"><span>Hydrogen sulfide production in surface layers of sediments in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> (from radioisotope data)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lein, A. Yu.; Ivanov, M. V.</p> <p>2015-11-01</p> <p>The report presents the results of 35S-radioisotope researches of sulfate reduction rates in Holocene sediments (0-20 cm) of the shelf and the continental slope at the eastern coasts of the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> from 81° N to 25° S, including sediments in the most environmentally hazardous upwelling zones. Data from experiments on the rates of sulfate reduction were used in calculating the production of hydrogen sulfide. The rates of sulfate reduction are comparable at the polar shelf and the <span class="hlt">equatorial</span> area of the influence of the Congo River (11.9 and 14.96 mg S/m2 day, respectively). It must be acknowledged that the production of microbial diagenetic hydrogen sulfide is first affected by the content and composition of organic matter in the sediments and secondly by the thermal conditions of the basin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002DSRI...49..605B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002DSRI...49..605B"><span>Biogeochemistry of Fe and other trace elements (Al, Co, Ni) in the upper <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bowie, Andrew R.; Whitworth, David J.; Achterberg, Eric P.; Mantoura, R. Fauzi C.; Worsfold, Paul J.</p> <p>2002-04-01</p> <p>Iron and other trace metals (Al, Co, Ni) were measured through the upper water column during two north-south transects of the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> (approximately 50°N-50°S), from the United Kingdom (UK) to the Falkland Islands (September/October 1996) and from South Africa to the UK (May/June 1998). Total dissolvable iron (TD-Fe) concentrations in the surface layers (<200 m) of the open <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> averaged 0.95±0.67 nM ( n=142) during the 1996 cruise and 1.08±0.59 nM ( n=160) during the 1998 cruise, with increased values in shelf waters at both extremes of the transects. Iron enrichments, fingerprinted via correlation with other trace metals, macronutrients and hydrography, correlated well with dry aerosol deposition off the west African continent and wet deposition in the Inter-Tropical Convergence Zone (ITCZ), with levels >2.2 nM observed in surface waters in these regions. Benthic fluxes provided a significant amount of Fe (2-38 nM) to the base of the water column in coastal zones. In addition, samples collected from one <span class="hlt">Atlantic</span> Meridional Transect (AMT) expedition were re-analysed after a 16 month acidification period and showed significant increases over shipboard analyses (average values increasing to 2.26±1.50 nM), indicating the extended release of Fe from leachable particulate material in the stored samples. Detailed profiling through the euphotic zone revealed TD-Fe distributions that exhibited strong relationships with biological uptake, regeneration and water column hydrography. In <span class="hlt">equatorial</span> and tropical North <span class="hlt">Atlantic</span> waters, trace elemental distributions showed evidence of recent atmospheric deposition through a history of stratified mixed layers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995GBioC...9..667M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995GBioC...9..667M"><span>Terrigenous Fe input and biogenic sedimentation in the glacial and interglacial <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Murray, R. W.; Leinen, M.; Murray, D. W.; Mix, A. C.; Knowlton, C. W.</p> <p>1995-12-01</p> <p>Many <span class="hlt">ocean</span> regions important to the global carbon budget, including the <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span>, have low chlorophyll concentrations despite high levels of conventional nutrients. Iron may instead be the limiting nutrient, and elevated input of terrigenous Fe during windy glacial episodes has been hypothesized to stimulate <span class="hlt">oceanic</span> productivity through time and thus regulate the <span class="hlt">oceanic</span> and atmospheric CO2 balance. To test whether particulate Fe input is related to the accumulation of biogenic matter in one important low chlorophyll-high nutrient area, that is, the <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span>, we present results from a suite of sediment cores that collectively record biogenic deposition through the last six glacial-interglacial cycles (˜600,000 years). Our data set includes new chemical data on total Fe, terrigenous, and biogenic components in three cores as well as previously published mineralogic records of eolian input to the region. Chemical, spectral, and stratigraphic analysis indicates that (1) terrigenous input to the region shows no consistent pattern of either glacial or interglacial maxima, (2) the accumulation of particulate Fe is closely related to the accumulation of terrigenous matter (linear r2 = 0.81-0.98), (3) there are no coherent spectral relationships between Fe input and glacial periodicity (i.e., δ18O) in any of the orbital frequency bands, (4) the linear and cross-spectral correlations between Fe or eolian input and CaCO3 concentration are most commonly the strongest observed relationships between Fe and any biogenic component, yet indicate a largely inverse pattern, with higher Fe being associated with low CaCO3, (5) there is no consistent linear r2 correlation or spectral coherence between the accumulation of Fe and that of CaCO3, Corg, or opal. Thus in total there is no relationship between terrigenous Fe input and sedimentary sequestering of carbon. Additionally, although we cannot specifically address the potential for changes in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4951652','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4951652"><span>Anomalous behaviors of Wyrtki Jets in the <span class="hlt">equatorial</span> Indian <span class="hlt">Ocean</span> during 2013</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Duan, Yongliang; Liu, Lin; Han, Guoqing; Liu, Hongwei; Yu, Weidong; Yang, Guang; Wang, Huiwu; Wang, Haiyuan; Liu, Yanliang; Zahid; Waheed, Hussain</p> <p>2016-01-01</p> <p>In-situ measurement of the upper <span class="hlt">ocean</span> velocity discloses significant abnormal behaviors of two Wyrtki Jets (WJs) respectively in boreal spring and fall, over the tropical Indian <span class="hlt">Ocean</span> in 2013. The two WJs both occurred within upper 130 m depth and persisted more than one month. The exceptional spring jet in May was unusually stronger than its counterpart in fall, which is clearly against the previous understanding. Furthermore, the fall WJ in 2013 unexpectedly peaked in December, one month later than its climatology. Data analysis and numerical experiments illustrate that the anomalous changes in the <span class="hlt">equatorial</span> zonal wind, associated with the strong intra-seasonal oscillation events, are most likely the primary reason for such anomalous WJs activities. PMID:27436723</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27084202','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27084202"><span>Polychlorinated naphthalenes in the air over the <span class="hlt">equatorial</span> Indian <span class="hlt">Ocean</span>: Occurrence, potential sources, and toxicity.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Huang, Yumei; Li, Jun; Xu, Yue; Xu, Weihai; Zhong, Guangcai; Liu, Xiang; Zhang, Gan</p> <p>2016-06-15</p> <p>Monitoring of marine polychlorinated naphthalenes (PCNs) is crucial, as they are considered persistent organic pollutants (POPs) by the Stockholm Convention. Data on PCNs in marine environment are scarce. In this study, 19 air samples were collected during a cruise in the <span class="hlt">equatorial</span> Indian <span class="hlt">Ocean</span> on board the Chinese research vessel Shiyan I from 4/2011 to 5/2011. PCN concentration of these air samples ranged from 0.033 to 2.56pgm(-3), with an average of 0.518pgm(-3), equal to or lower than the values reported for other <span class="hlt">oceans</span>, seas, and lakes worldwide. Tri- and tetra-CNs were the main homologues in most samples. Reemission of Halowax mixtures and incineration processes were the major sources of atmospheric PCNs in the study area. The PCN-corresponding toxic equivalency values ranged from 0 to 0.190fgm(-3) (average: 0.038fgm(-3)), falling in the low end of global range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860042337&hterms=indian+ocean+earthquakes&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dindian%2Bocean%2Bearthquakes','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860042337&hterms=indian+ocean+earthquakes&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dindian%2Bocean%2Bearthquakes"><span>Historical seismicity near Chagos - A complex deformation zone in the <span class="hlt">equatorial</span> Indian <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wiens, D. A.</p> <p>1986-01-01</p> <p>The historical seismicity of the Chagos region of the Indian <span class="hlt">Ocean</span> is analyzed, using earthquake relocation methods and a moment variance technique to determine the focal mechanisms of quakes occurring before 1964. Moment variance analysis showed a thrust faulting mechanism associated with the earthquake of 1944 near the Chagos-Laccadive Ridge; a strike-slip mechanism was associated with a smaller 1957 event occurring west of the Chagos Bank. The location of the 1944 event, one of the largest intraplate earthquakes known (1.4 x 10 to the 27th dyne/cm), would imply that the Chagos seismicity is due to a zone of tectonic deformation stretching across the <span class="hlt">equatorial</span> Indian <span class="hlt">Ocean</span>. The possibility of a slow diffuse boundary extending west of the Central Indian Ridge is also discussed. This boundary is confirmed by recent plate motion studies which suggest that it separates the Australian plate from a single Indo-Arabian plate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860042337&hterms=Seismicity+plate+tectonics&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DSeismicity%2Bplate%2Btectonics','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860042337&hterms=Seismicity+plate+tectonics&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DSeismicity%2Bplate%2Btectonics"><span>Historical seismicity near Chagos - A complex deformation zone in the <span class="hlt">equatorial</span> Indian <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wiens, D. A.</p> <p>1986-01-01</p> <p>The historical seismicity of the Chagos region of the Indian <span class="hlt">Ocean</span> is analyzed, using earthquake relocation methods and a moment variance technique to determine the focal mechanisms of quakes occurring before 1964. Moment variance analysis showed a thrust faulting mechanism associated with the earthquake of 1944 near the Chagos-Laccadive Ridge; a strike-slip mechanism was associated with a smaller 1957 event occurring west of the Chagos Bank. The location of the 1944 event, one of the largest intraplate earthquakes known (1.4 x 10 to the 27th dyne/cm), would imply that the Chagos seismicity is due to a zone of tectonic deformation stretching across the <span class="hlt">equatorial</span> Indian <span class="hlt">Ocean</span>. The possibility of a slow diffuse boundary extending west of the Central Indian Ridge is also discussed. This boundary is confirmed by recent plate motion studies which suggest that it separates the Australian plate from a single Indo-Arabian plate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMOS11B..03B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMOS11B..03B"><span>Deep <span class="hlt">Ocean</span> Motion: Pacific <span class="hlt">Equatorial</span> Thermostad Response to El Niño</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Birnbaum, A. N.; Johnson, G. C.</p> <p>2016-12-01</p> <p>El Niños are characterized by a shift of warm surface water from the western to eastern <span class="hlt">equatorial</span> Pacific due to weakening of easterly trade winds. This shift of warm water causes the thermocline, the large vertical temperature gradient beneath the surface mixed layer, to shoal in the west and deepen in the east, inducing a redistribution of <span class="hlt">ocean</span> heat that affects global mean values. The effects of El Niños on the <span class="hlt">ocean</span> beneath the thermocline are important for a comprehensive understanding of the impact of these events. Hence we examine the response of the Pacific <span class="hlt">Equatorial</span> Thermostad, a layer of low vertical stratification below the thermocline, to El Niño using a monthly Argo float climatology from January 2004 through June 2016 and Argo float deep velocity data. We fit a mean, seasonal cycle, trend, and linear response to the Niño3.4 index to temperature and salinity at each gridpoint and to deep float velocities to characterize physical properties in the thermostad, including layer thickness and velocity. We compare these properties for neutral conditions (Niño3.4 = 0) versus those during a moderate El Niño (Niño3.4 = 1). During an El Niño, a strengthening of the westward-flowing <span class="hlt">Equatorial</span> Intermediate Current of order 3 x 106 m3 s-1 shifts about 7 x 1013 m3 of thermostad water from the east to the west, allowing conservation of volume within the thermostad as the thermocline above deepens in the east and shoals in the west. This transport and volume change imply a 9-month time scale, consistent with El Niño.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRC..122.3240W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRC..122.3240W"><span>Mechanism of seasonal eddy kinetic energy variability in the eastern <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Minyang; Du, Yan; Qiu, Bo; Cheng, Xuhua; Luo, Yiyong; Chen, Xiao; Feng, Ming</p> <p>2017-04-01</p> <p>Enhanced mesoscale eddy activities or tropical instability waves (TIWs) exist along the northern front of the cold tongue in the eastern <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span>. In this study, we investigate seasonal variability of eddy kinetic energy (EKE) over this region and its associated dynamic mechanism using a global, eddy-resolving <span class="hlt">ocean</span> general circulation model (OGCM) simulation, the <span class="hlt">equatorial</span> mooring data, and satellite altimeter observations. The seasonal-varying enhanced EKE signals are found to expand westward from 100°W in June to 180°W in December between 0°N and 6°N. This westward expansion in EKE is closely connected to the barotropically-baroclinically unstable zonal flows that are in thermal-wind balance with the seasonal-varying thermocline trough along 4°N. By adopting an 1½-layer reduced-gravity model, we confirm that the seasonal perturbation of the thermocline trough is dominated by the anticyclonic wind stress curl forcing, which develops due to southerly winds along 4°N from June to December.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JOUC...11..547S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JOUC...11..547S"><span>Modeling the hook depth distribution of pelagic longlining in the <span class="hlt">equatorial</span> area of Indian <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Song, Liming; Li, Jie; Gao, Panfeng; Zhou, Ji; Xu, Liuxiong</p> <p>2012-12-01</p> <p>A survey was conducted in the <span class="hlt">equatorial</span> area of Indian <span class="hlt">Ocean</span> for a better understanding of the dynamics of hook depth distribution of pelagic longline fishery. We determined the relationship between hook depth and vertical shear of current coefficiency, wind speed, hook position code, sine of wind angle, sine of angle of attack and weight of messenger weight. We identified the hook depth models by the analysis of covariance with a general linear model. The results showed that the wind effect on the hook depth can be ignored from October to November in the survey area; the surface current effect on the hook depth can be ignored; the <span class="hlt">equatorial</span> undercurrent is the key factor for the hook depth in Indian <span class="hlt">Ocean</span>; and there is a negative correlation between the hook depth and vertical shear of current and angle of attack. It was also found that the deeper the hook was set, the higher hook depth shoaling was. The proposed model improves the accuracy of the prediction of hook depth, which can be used to estimate the vertical distribution of pelagic fish in water column.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.T41D2926S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.T41D2926S"><span>Seismic Reflection Imaging of the Lithosphere-asthenosphere Boundary Across the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Singh, S. C.; Marjanovic, M.; Audhkhasi, P.; Mehouachi, F.</p> <p>2015-12-01</p> <p>Until now, the nature of the lithosphere-asthenosphere boundary (LAB) has been constrained by teleseismic data, which has resolution of tens of kilometres and sample the LAB sparsely. Seismic reflection imaging technique, in contrast, can provide both lateral and vertical resolution of a few hundred meters, but has not been used for imaging deep structures, thus so far. In March-April 2015, we acquired over 2,750 km of ultra-deep seismic reflection data in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>. To image LAB variations as a function of age one of our profiles extends continuously starting from 75 Ma old <span class="hlt">oceanic</span> lithosphere off the margin of Africa, crosses the Mid-<span class="hlt">Atlantic</span> Ridge at zero age, to up to 25 Ma old South America lithosphere. To image large differences in the LAB depth we also cross three major fracture zones in the <span class="hlt">equatorial</span> <span class="hlt">Atlantic</span>. For imaging deep structures, we used a very large energy source, 10,170 cubic inches, rich in low frequencies and a 12 km long multi-component streamer allowing to record low frequency energy reflected from deep earth and remove reverberation in the water column. Initial results show reflected seismic energy from 50-60 km depth. The seismic reflection experiment will be complemented by seismic refraction study to determine the crustal and upper mantle P-wave velocity, magnetotelluric study to determine resistivity, and broadband <span class="hlt">ocean</span> bottom seismometer experiment for teleseismic study, collocated with our seismic reflection profiles. In this paper, we will present the design of the seismic reflection experiment and preliminary results from the onboard processed data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.8815M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.8815M"><span>Impact of the salt leakage through the Indian-<span class="hlt">Atlantic</span> <span class="hlt">ocean</span> gateway on the <span class="hlt">Atlantic</span> MOC</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marino, G.; Zahn, R.; Ziveri, P.; Ziegler, M.; Hall, I. R.; Elderfield, H.</p> <p>2012-04-01</p> <p>Freshwater perturbation in the northern North <span class="hlt">Atlantic</span> exerts a strong influence on the stability of the <span class="hlt">Atlantic</span> meridional overturning circulation (AMOC) with potentially severe impacts on the regional and global climates. The occurrence of ice rafted detritus (IRD) in the glacial sediments of the North <span class="hlt">Atlantic</span> testifies to past episodes of Laurentide ice sheet surging that also coincided with AMOC curtailments and prominent climate deterioration in the Northeast <span class="hlt">Atlantic</span> and Western Europe. The equally abrupt warming shifts observed in Greenland ice core and North <span class="hlt">Atlantic</span> sediment core records that characterize the end of each IRD event have been related to the rapid resumption of AMOC and its associated heat transport. The hysteresis response, under glacial boundary conditions, of the AMOC to freshwater forcing suggests that a reduction in this forcing may have been sufficient to trigger the rapid AMOC resumptions revealed by several palaeoceanographic records. But recent modelling studies allude to the potential importance of a salt surplus, originating in the Indian <span class="hlt">Ocean</span> and transported to the South <span class="hlt">Atlantic</span> via the Agulhas leakage, that may have acted as a positive feedback on the AMOC strengthening. This possibility, however, has yet to be adequately tested with palaeoproxy reconstructions. We present a suite of multi-centennial-scale palaeoceanographic records spanning a full glacial cycle from the Southwest African margin and Agulhas Plateau that have been generated as part of the EU Marie Curie GATEWAYS project. The sediment cores are positioned such that they monitor the leakage of Agulhas water into the <span class="hlt">Atlantic</span> and the Agulhas Return Current that straddles the South <span class="hlt">Atlantic</span> subtropical front on its way to the Indian <span class="hlt">Ocean</span>. Paired Mg/Ca-δ18O analyses on the planktonic foraminifera Globigerinoides ruber and Globigerina bulloides reveal millennial-scale surface <span class="hlt">ocean</span> temperature and salinity changes at the core sites that reflect recurrent</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040191710&hterms=mit&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmit','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040191710&hterms=mit&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmit"><span>Subduction in an Eddy-Resolving State Estimate of the Northeast <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gebbie, Geoffrey</p> <p>2004-01-01</p> <p>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 <span class="hlt">ocean</span> 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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> 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 <span class="hlt">Atlantic</span> 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 <span class="hlt">Equatorial</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013ClDy...41..677N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ClDy...41..677N"><span>Simulated impacts of the South <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> Dipole on summer precipitation at the Guinea Coast</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nnamchi, Hyacinth C.; Li, Jianping; Kang, In-Sik; Kucharski, Fred</p> <p>2013-08-01</p> <p>An intermediate complexity atmospheric general circulation model has been used to investigate the influence of the South <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> (SAO) dipole (SAOD) on summer precipitation over the Guinea Coast of West Africa. Two ensemble integrations in which idealized but realistic SAOD-type sea surface temperature (SST) anomaly is prescribed only in the SAO, and then globally are performed and inter-compared. Consistently, above (below) the average precipitation is simulated over the Guinea Coast during the positive (negative) phase of the SAOD. Comparison of the two set of experiments reveal that in its active years, the SAOD is a dominant mechanism that shapes the spatial character of summer precipitation at the Guinea coast, the global SST variability merely slightly moderate its effects. During the SAOD, cool SST anomaly in the extra-tropical SAO off the Brazil-Uruguay-Argentina coast gives rise to suppressed convection and mass divergence. In turn, the subsidence tends to amplify the sub-tropical arm of anomalous Hadley-type circulation and consequently large scale convection and mass flux convergence in the <span class="hlt">equatorial</span> <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>/Gulf of Guinea region bordering on the coastal fringes of West Africa. Precipitation is therefore increased at the Guinea Coast.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1077368','SCIGOV-DOEDE'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1077368"><span>CARINA (Carbon dioxide in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>) Data from CDIAC</span></a></p> <p><a target="_blank" href="http://www.osti.gov/dataexplorer">DOE Data Explorer</a></p> <p></p> <p></p> <p>The idea for CARINA developed at a workshop (CO2 in the northern North <span class="hlt">Atlantic</span>) that was held at the HANSE-Wissenschaftskolleg (HANSE Institute for Advanced Study) in Delmenhorst, Germany from June 9 to 11, 1999. While the main scientific focus is the North <span class="hlt">Atlantic</span>, some data from the South <span class="hlt">Atlantic</span> have been included in the project, along with data from the Arctic <span class="hlt">Ocean</span>. Data sets go back to 1972, and more than 100 are currently available. The data are also being used in conjunction with other projects and research groups, such as the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> Carbon Synthesis Group. See the inventory of data at http://store.pangaea.de/Projects/CARBOOCEAN/carina/data_inventory.htm See a detailed table of information on the cruises at http://cdiac.ornl.gov/<span class="hlt">oceans</span>/CARINA/Carina_table.html and also provides access to data files. The CARBOOCEAN data portal provides a specialized interface for CARINA data, a reference list for historic carbon data, and password protected access to the "Data Underway Warehouse.".</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRC..122.3200C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRC..122.3200C"><span>Dynamics of Andaman Sea circulation and its role in connecting the <span class="hlt">equatorial</span> Indian <span class="hlt">Ocean</span> to the Bay of Bengal</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chatterjee, Abhisek; Shankar, D.; McCreary, J. P.; Vinayachandran, P. N.; Mukherjee, A.</p> <p>2017-04-01</p> <p>Circulation in the Bay of Bengal (BoB) is driven not only by local winds, but are also strongly forced by the reflection of <span class="hlt">equatorial</span> Kelvin waves (EKWs) from the eastern boundary of the Indian <span class="hlt">Ocean</span>. The <span class="hlt">equatorial</span> influence attains its peak during the monsoon-transition period when strong eastward currents force the strong EKWs along the equator. The Andaman Sea, lying between the Andaman and Nicobar island chains to its west and Indonesia, Thailand, and Myanmar to the south, east, and north, is connected to the <span class="hlt">equatorial</span> <span class="hlt">ocean</span> and the BoB by three primary passages, the southern (6°N), middle (10°N), and northern (15°N) channels. We use <span class="hlt">ocean</span> circulation models, together with satellite altimeter data, to study the pathways by which <span class="hlt">equatorial</span> signals pass through the Andaman Sea to the BoB and associated dynamical interactions in the process. The mean coastal circulation within the Andaman Sea and around the islands is primarily driven by <span class="hlt">equatorial</span> forcing, with the local winds forcing a weak sea-level signal. On the other hand, the current forced by local winds is comparable to that forced remotely from the equator. Our results suggest that the Andaman and Nicobar Islands not only influence the circulation within the Andaman Sea, but also significantly alter the circulation in the interior bay and along the east coast of India, implying that they need to be represented accurately in numerical models of the Indian <span class="hlt">Ocean</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoRL..44.4985S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoRL..44.4985S"><span>Multidecadal variability and climate shift in the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Seidov, Dan; Mishonov, Alexey; Reagan, James; Parsons, Rost</p> <p>2017-05-01</p> <p>Decadal variability of <span class="hlt">ocean</span> heat content (OHC) and temperature trends over 60 years in the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> were analyzed using a new high-resolution <span class="hlt">ocean</span> climatology based on quality-controlled historic in situ observations. Two 30 year <span class="hlt">ocean</span> climates of 1955-1984 and 1985-2012 were compared to evaluate the climate shift in this region. The spatial distribution of the OHC climate shift is highly inhomogeneous, with the climate shift being the strongest southeast of the Gulf Stream Extension. This may be caused by the <span class="hlt">Atlantic</span> Meridional Overturning Circulation slowdown in conjunction with heaving of warm subtropical water. The 30 year climate shift shows higher OHC gain in the Gulf Stream region than reported in shorter timescale estimates. The OHC change is generally coherent with the <span class="hlt">Atlantic</span> Multidecadal Oscillation index. This coherence suggests that quasi-cyclicity of the OHC may exist, with a period of 60 to 80 years, superimposed on the slow basin-wide warming trend.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Natur.511..212C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Natur.511..212C"><span>Quantification of dissolved iron sources to the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Conway, Tim M.; John, Seth G.</p> <p>2014-07-01</p> <p>Dissolved iron is an essential micronutrient for marine phytoplankton, and its availability controls patterns of primary productivity and carbon cycling throughout the <span class="hlt">oceans</span>. The relative importance of different sources of iron to the <span class="hlt">oceans</span> is not well known, however, and flux estimates from atmospheric dust, hydrothermal vents and <span class="hlt">oceanic</span> sediments vary by orders of magnitude. Here we present a high-resolution transect of dissolved stable iron isotope ratios (δ56Fe) and iron concentrations ([Fe]) along a section of the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>. The different iron sources can be identified by their unique δ56Fe signatures, which persist throughout the water column. This allows us to calculate the relative contribution from dust, hydrothermal venting and reductive and non-reductive sedimentary release to the dissolved phase. We find that Saharan dust aerosol is the dominant source of dissolved iron along the section, contributing 71-87 per cent of dissolved iron. Additional sources of iron are non-reductive release from oxygenated sediments on the North American margin (10-19 per cent), reductive sedimentary dissolution on the African margin (1-4 per cent) and hydrothermal venting at the Mid-<span class="hlt">Atlantic</span> Ridge (2-6 per cent). Our data also indicate that hydrothermal vents in the North <span class="hlt">Atlantic</span> are a source of isotopically light iron, which travels thousands of kilometres from vent sites, potentially influencing surface productivity. Changes in the relative importance of the different iron sources through time may affect interactions between the carbon cycle and climate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5075798','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5075798"><span><span class="hlt">Ocean</span> feedback to pulses of the Madden–Julian Oscillation in the <span class="hlt">equatorial</span> Indian <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Moum, James N.; Pujiana, Kandaga; Lien, Ren-Chieh; Smyth, William D.</p> <p>2016-01-01</p> <p>Dynamical understanding of the Madden–Julian Oscillation (MJO) has been elusive, and predictive capabilities therefore limited. New measurements of the <span class="hlt">ocean</span>'s response to the intense surface winds and cooling by two successive MJO pulses, separated by several weeks, show persistent <span class="hlt">ocean</span> currents and subsurface mixing after pulse passage, thereby reducing <span class="hlt">ocean</span> heat energy available for later pulses by an amount significantly greater than via atmospheric surface cooling alone. This suggests that thermal mixing in the upper <span class="hlt">ocean</span> from a particular pulse might affect the amplitude of the following pulse. Here we test this hypothesis by comparing 18 pulse pairs, each separated by <55 days, measured over a 33-year period. We find a significant tendency for weak (strong) pulses, associated with low (high) cooling rates, to be followed by stronger (weaker) pulses. We therefore propose that the <span class="hlt">ocean</span> introduces a memory effect into the MJO, whereby each event is governed in part by the previous event. PMID:27759016</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27759016','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27759016"><span><span class="hlt">Ocean</span> feedback to pulses of the Madden-Julian Oscillation in the <span class="hlt">equatorial</span> Indian <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Moum, James N; Pujiana, Kandaga; Lien, Ren-Chieh; Smyth, William D</p> <p>2016-10-19</p> <p>Dynamical understanding of the Madden-Julian Oscillation (MJO) has been elusive, and predictive capabilities therefore limited. New measurements of the <span class="hlt">ocean</span>'s response to the intense surface winds and cooling by two successive MJO pulses, separated by several weeks, show persistent <span class="hlt">ocean</span> currents and subsurface mixing after pulse passage, thereby reducing <span class="hlt">ocean</span> heat energy available for later pulses by an amount significantly greater than via atmospheric surface cooling alone. This suggests that thermal mixing in the upper <span class="hlt">ocean</span> from a particular pulse might affect the amplitude of the following pulse. Here we test this hypothesis by comparing 18 pulse pairs, each separated by <55 days, measured over a 33-year period. We find a significant tendency for weak (strong) pulses, associated with low (high) cooling rates, to be followed by stronger (weaker) pulses. We therefore propose that the <span class="hlt">ocean</span> introduces a memory effect into the MJO, whereby each event is governed in part by the previous event.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26216947','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26216947"><span>Decadal acidification in the water masses of the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ríos, Aida F; Resplandy, Laure; García-Ibáñez, Maribel I; Fajar, Noelia M; Velo, Anton; Padin, Xose A; Wanninkhof, Rik; Steinfeldt, Reiner; Rosón, Gabriel; Pérez, Fiz F</p> <p>2015-08-11</p> <p>Global <span class="hlt">ocean</span> acidification is caused primarily by the <span class="hlt">ocean</span>'s uptake of CO2 as a consequence of increasing atmospheric CO2 levels. We present observations of the <span class="hlt">oceanic</span> decrease in pH at the basin scale (50 °S-36 °N) for the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> over two decades (1993-2013). Changes in pH associated with the uptake of anthropogenic CO2 (ΔpHCant) and with variations caused by biological activity and <span class="hlt">ocean</span> circulation (ΔpHNat) are evaluated for different water masses. Output from an Institut Pierre Simon Laplace climate model is used to place the results into a longer-term perspective and to elucidate the mechanisms responsible for pH change. The largest decreases in pH (∆pH) were observed in central, mode, and intermediate waters, with a maximum ΔpH value in South <span class="hlt">Atlantic</span> Central Waters of -0.042 ± 0.003. The ΔpH trended toward zero in deep and bottom waters. Observations and model results show that pH changes generally are dominated by the anthropogenic component, which accounts for rates between -0.0015 and -0.0020/y in the central waters. The anthropogenic and natural components are of the same order of magnitude and reinforce one another in mode and intermediate waters over the time period. Large negative ΔpHNat values observed in mode and intermediate waters are driven primarily by changes in CO2 content and are consistent with (i) a poleward shift of the formation region during the positive phase of the Southern Annular Mode in the South <span class="hlt">Atlantic</span> and (ii) an increase in the rate of the water mass formation in the North <span class="hlt">Atlantic</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1982GeCoA..46.2239W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1982GeCoA..46.2239W"><span>Organic matter from a sediment trap experiment in the <span class="hlt">equatorial</span> north <span class="hlt">Atlantic</span>: wax esters, steryl esters, triacylglycerols and alkyldiacylglycerols</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wakeham, Stuart G.</p> <p>1982-11-01</p> <p>The vertical flux and composition of wax esters, steryl esters, triacylglycerols, and alkyldiacylglycerols in particulate matter was determined in the <span class="hlt">equatorial</span> <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> by deploying sediment traps at 389, 988, 3,755 and 5,068 m. Detailed compositional analyses of these lipids were carried out by high temperature glass capillary gas chromatography and gas chromatography/mass spectrometry. The distributions of these lipids are discussed in terms of potential biological sources. Zooplankton fecal matter and intact zooplankters may represent the most important input of these compounds to the shallower two traps, while the material in the deeper two traps appears to have been biogeochemically altered. The finding of these biochemically important compounds, often unsaturated, indicates that particle transit through the water column must be relatively fast. Wax esters were most abundant in the 389 m sediment trap and decreased with increasing trap depth. Compounds ranging from C 28-C 44 were present at all depths. The major homologs were C 32, C 34 and C 36, most often monounsaturated. The dominant alcohol/acid combinations in the 389 m trap were C 18:1/C 14:0 and C 18:1/C 16:0, but in the 988 m sample, C 16:0/C 18:1 was the major wax ester. A flux maximum was observed for steryl esters at 988 m. Cholesteryl esters of C 14:0, C 16:1 and C 16:0, and C 18:1/C 18:0 fatty acids were the dominant steryl esters. For triacylglycerols, fluxes in the 389 and 988 m traps were similar, while the deeper pair of traps contained much less triacylglycerol. C 46, C 48, C 50 and C 52 compounds were the major triacylglycerols. Constituent fatty acids in the 389 m and 988 m samples were mainly C 14:0, C 16:1, C 16:0, C 18:1 and C 18:0. In the 988 m material, C 20:5 and C 22:6 were also dominant. A homologous series of alkyldiacylglycerols was abundant in the 389 m trap material. The alkyldiacylglycerols consisted of C 46-C 56 compounds composed of C 16:0 alkyl moieties and C 14:0, C</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSPO14E2863P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSPO14E2863P"><span>On How the Seasonal Variability of the ITCZ Drives Subtropical-Tropical Exchange in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pelegrí, J. L.; Castellanos, P.; Emelianov, M. V.; Gasser, M.; Gourrion, J.; Peña-Izquierdo, J.; Rosell-Fieschi, M.</p> <p>2016-02-01</p> <p>The Inter-Tropical Convergence Zone (ITCZ) oscillates seasonally in the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, its mean position moving between the Equator in February and 10°N in August-September. Further, during its annual march, the ITCZ remains oriented SW-NE, with 10° of latitude difference across the <span class="hlt">Atlantic</span>. As a consequence, Ekman convergence-divergence changes zonally and seasonally, setting up the sea-surface absolute dynamic topography (ADT) that drives geostrophic currents in the tropical <span class="hlt">ocean</span> and the adjacent subtropical gyres. The clearest example is the seasonal growth of the North <span class="hlt">Equatorial</span> Counter Current (NECC) at 6-8°N, as an intense eastward jet in the tropical North <span class="hlt">Atlantic</span> amid the westward South <span class="hlt">Equatorial</span> Current (SEC). The NECC starts in the eastern <span class="hlt">Atlantic</span> in May and progresses west, fed by a northern diversion of the SEC, until it reaches the western boundary in August, causing the retroflection of the North Brazil Current (NBC). The NECC results from the boreal-summer northward penetration of the ITCZ and the associated South <span class="hlt">Atlantic</span> High: the surface winds cause zonal bands of meridional Ekman convergence (3-7°N) and divergence (7-13°N) that lead to a ridge-valley ADT pattern, with the NECC unfolding at those latitudes of large latitudinal ADT gradients (6-8°N). The NECC intensifies through input from the interior gyres - anticyclonic near the low-latitude ridge and cyclonic around the northern valley, the latter related to the northern subtropical cell - and only after August it fuels from the NBC retroflection. The northern position of the ITCZ prevents analogous jets and retroflections to occur in the southern hemisphere, yet the location where the SEC bifurcates (into the northward NBC and the southward Brazil Current) changes between January (8°S) and June (16°S). Further, between April and July, a ridge-valley ADT distribution appears in the western tropical South <span class="hlt">Atlantic</span>, giving rise to cyclonic-anticyclonic motions near 12°S-6</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMPP22B..03R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMPP22B..03R"><span>Deglacial <span class="hlt">Atlantic</span> Radiocarbon: A Southern <span class="hlt">Ocean</span> Perspective</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Robinson, L. F.; Burke, A.; Adkins, J. F.; Chen, T.; Spooner, P.</p> <p>2014-12-01</p> <p>It is widely accepted that the Southern <span class="hlt">Ocean</span> is an important component of the climate system, acting as a key site for carbon and heat exchange between the atmosphere and <span class="hlt">oceans</span>. The deglaciation with its associated millenial climate changes is a key time period for testing the mechanisms behind these exchanges. Ascertaining the precise timing of these events is a challenge given complications from variable and largely unconstrained reservoir ages, dissolution of carbonate hard parts and sediment redistribution by strong currents. Nevertheless improvements to our understanding of Southern <span class="hlt">Ocean</span> dynamics in the past requires accurately-dated proxy records that can be embedded in GCM models. Radiocarbon measured in deep-sea corals offers just such an archive and proxy. Using the skeletons of deep-sea corals we are now able to reconstruct aspects of the history of three distinct water masses in the Drake Passage on a precise timescale, allowing direct comparison to U-series dated speleothem terrestrial records and polar ice cores. We present here a new deglacial radiocarbon record from the Drake Passage which more than doubles the resolution of published records. We focus on the deglacial, as well as providing insights from the contrasting period leading up to the LGM. Together with new data from far-field sites we interpret our results as evidence for a Southern <span class="hlt">Ocean</span> control on atmospheric carbon dioxide and radiocarbon evolution during the deglaciation, and a northern hemisphere control during the run up to the LGM.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PrOce.128..172L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PrOce.128..172L"><span>Organic pollutants and <span class="hlt">ocean</span> fronts across the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>: A review</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lohmann, Rainer; Belkin, Igor M.</p> <p>2014-11-01</p> <p>Little is known about the effect of <span class="hlt">ocean</span> fronts on pollutants dynamics, particularly organic pollutants. Since fronts are associated with convergent currents and productive fishing grounds, any possible convergence of pollutants at fronts would raise concerns. The focus here is on relatively persistent organic pollutants, POPs, as non-persistent organic pollutants are rarely found in the open <span class="hlt">ocean</span>. Results from recent cruises in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> are examined for POP distributions across <span class="hlt">ocean</span> fronts in (i) the Canary Current; (ii) the Gulf Stream; and (iii) the Amazon and Rio de la Plata Plumes. Few studies achieved a spatial resolution of 10-20 km, while most had 100-300 km between adjacent stations. The majority of the well-resolved studies measured perfluorinated compounds (PFCs), which seem particularly well suited for frontal resolution. In the NE <span class="hlt">Atlantic</span>, concentrations of PFCs sharply decreased between SW Europe and NW Africa upon crossing the Canary Current Front at 24-27°N. In the Western <span class="hlt">Atlantic</span>, the PFC concentrations sharply increased upon entering the Amazon River Plume and Rio de la Plata Plume. In the NW <span class="hlt">Atlantic</span>, concentrations of several pollutants such as polycyclic aromatic hydrocarbons are very high in Rhode Island Sound, decreasing to below detection limit in the open <span class="hlt">ocean</span>. The more persistent and already phased-out polychlorinated biphenyls (PCBs) displayed elevated concentrations in the Gulf Stream and Rhode Island Sound, thereby highlighting the importance of <span class="hlt">ocean</span> fronts, along-front currents, and cross-frontal transport for the dispersal of PCBs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2012-02-27/pdf/2012-4452.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2012-02-27/pdf/2012-4452.pdf"><span>77 FR 11387 - Safety Zone; Lauderdale Air Show, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Fort Lauderdale, FL</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2012-02-27</p> <p>... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Lauderdale Air Show, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Fort... establishing a temporary safety zone on the waters of the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> in the vicinity of Fort Lauderdale... Lauderdale Air Show will include numerous aircraft engaging in aerobatic maneuvers over the <span class="hlt">Atlantic</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23538831','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23538831"><span>Deglacial pulses of deep-<span class="hlt">ocean</span> silicate into the subtropical North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Meckler, A N; Sigman, D M; Gibson, K A; François, R; Martínez-García, A; Jaccard, S L; Röhl, U; Peterson, L C; Tiedemann, R; Haug, G H</p> <p>2013-03-28</p> <p>Growing evidence suggests that the low atmospheric CO2 concentration of the ice ages resulted from enhanced storage of CO2 in the <span class="hlt">ocean</span> interior, largely as a result of changes in the Southern <span class="hlt">Ocean</span>. Early in the most recent deglaciation, a reduction in North <span class="hlt">Atlantic</span> overturning circulation seems to have driven CO2 release from the Southern <span class="hlt">Ocean</span>, but the mechanism connecting the North <span class="hlt">Atlantic</span> and the Southern <span class="hlt">Ocean</span> remains unclear. Biogenic opal export in the low-latitude <span class="hlt">ocean</span> relies on silicate from the underlying thermocline, the concentration of which is affected by the circulation of the <span class="hlt">ocean</span> interior. Here we report a record of biogenic opal export from a coastal upwelling system off the coast of northwest Africa that shows pronounced opal maxima during each glacial termination over the past 550,000 years. These opal peaks are consistent with a strong deglacial reduction in the formation of silicate-poor glacial North <span class="hlt">Atlantic</span> intermediate water (GNAIW). The loss of GNAIW allowed mixing with underlying silicate-rich deep water to increase the silicate supply to the surface <span class="hlt">ocean</span>. An increase in westerly-wind-driven upwelling in the Southern <span class="hlt">Ocean</span> in response to the North <span class="hlt">Atlantic</span> change has been proposed to drive the deglacial rise in atmospheric CO2 (refs 3, 4). However, such a circulation change would have accelerated the formation of Antarctic intermediate water and sub-Antarctic mode water, which today have as little silicate as North <span class="hlt">Atlantic</span> Deep Water and would have thus maintained low silicate concentrations in the <span class="hlt">Atlantic</span> thermocline. The deglacial opal maxima reported here suggest an alternative mechanism for the deglacial CO2 release. Just as the reduction in GNAIW led to upward silicate transport, it should also have allowed the downward mixing of warm, low-density surface water to reach into the deep <span class="hlt">ocean</span>. The resulting decrease in the density of the deep <span class="hlt">Atlantic</span> relative to the Southern <span class="hlt">Ocean</span> surface promoted Antarctic overturning</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V12A..07S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V12A..07S"><span>Seismicity of the <span class="hlt">Equatorial</span> Mid-<span class="hlt">Atlantic</span> Ridge and its Large Offset Transforms recorded during a multi-year hydrophone array deployment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, D. K.; Dziak, R. P.; Haxel, J.; Meyer, R. P.</p> <p>2015-12-01</p> <p>To increase our understanding of the slow-spreading, <span class="hlt">equatorial</span> Mid-<span class="hlt">Atlantic</span> Ridge (MAR), we deployed an array of eight autonomous hydrophones centered on the ridge axis between ~20°N and ~10°S. The hydrophones were deployed for 2+ years (500 Hz sample rate) and obtained a continuous record of the regional seismicity. This region is especially interesting for many reasons. A strongly segmented MAR is offset by some of the longest transform faults in the global <span class="hlt">oceans</span>. In addition, the North America-South America-Africa (NA-SA-AF) triple junction is thought to be between 10°N and 20°N at the MAR, but its exact location is not well-defined. And finally, the NA-SA plate boundary is not clearly delineated by teleseismicity or prominent seafloor structures despite known relative motion between the plates. Seven of the eight hydrophones were recovered in January 2015 and earthquake location analysis is underway. These seismic data will be used to understand the modes of spreading, short-term earthquake predictability, and triple junction dynamics. In particular, we will use patterns in the earthquake data to address the following: 1) Whether long-lived detachment faults play a central role in accretion at the <span class="hlt">equatorial</span> MAR similar to what is observed to the north (Escartin et al., 2008). 2) Whether foreshock sequences can be used to predict (retrospectively) earthquakes with magnitudes ≥ 5.4 mb on <span class="hlt">equatorial</span> <span class="hlt">Atlantic</span> transform faults as they can be on Pacific transforms (McGuire et al., 2005). A total of eighteen teleseismic earthquakes ≥ 5.4 mb occurred in this region during the hydrophone deployment providing a robust data base to test this foreshock precursor hypothesis. 3) Lastly, whether or not the geometry and crustal stress patterns induced by the NA-SA-AF triple junction are apparent in the earthquake data. If so, the earthquake patterns will help improve our understanding of triple junction dynamics and overall lithospheric strength.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRD..121.2045B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRD..121.2045B"><span>Impact of atmospheric convectively coupled <span class="hlt">equatorial</span> Kelvin waves on upper <span class="hlt">ocean</span> variability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baranowski, Dariusz B.; Flatau, Maria K.; Flatau, Piotr J.; Matthews, Adrian J.</p> <p>2016-03-01</p> <p>Convectively coupled Kelvin waves (CCKWs) are atmospheric weather systems that propagate eastward along the <span class="hlt">equatorial</span> wave guide with phase speeds between 11 and 14 m s-1. They are an important constituent of the convective envelope of the Madden-Julian oscillation (MJO), for which <span class="hlt">ocean</span>-atmosphere interactions play a vital role. Hence, <span class="hlt">ocean</span>-atmosphere interactions within CCKWs may be important for MJO development and prediction and for tropical climate, in general. Although the atmospheric structure of CCKWs has been well studied, their impact on the underlying <span class="hlt">ocean</span> is unknown. In this paper, the <span class="hlt">ocean</span>-atmosphere interactions in CCKWs are investigated by a case study from November 2011 during the CINDY/DYNAMO field experiment, using in situ oceanographic measurements from an <span class="hlt">ocean</span> glider. The analysis is then extended to a 15 year period using precipitation data from the Tropical Rainfall Measuring Mission and surface fluxes from the TropFlux analysis. A methodology is developed to calculate trajectories of CCKWs. CCKW events are strongly controlled by the MJO, with twice as many CCKWs observed during the convectively active phase of the MJO compared to the suppressed phase. Coherent <span class="hlt">ocean</span>-atmosphere interaction is observed during the passage of a CCKW, which lasts approximately 4 days at any given longitude. Surface wind speed and latent heat flux are enhanced, leading to a transient suppression of the diurnal cycle of sea surface temperature (SST) and a sustained decrease in bulk SST of 0.1°C. Given that a typical composite mean MJO SST anomaly is of the order of 0.3°C, and more than one CCKW can occur during the active phase of a single MJO event, the oceanographic impact of CCKWs is of major importance to the MJO cycle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.7619W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.7619W"><span>Diverse Manifestations of Convective Upwelling Beneath the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>White, Nicky; Parnell-Turner, Ross</p> <p>2013-04-01</p> <p>The Icelandic Plume dominates the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>. Residual depth anomalies of <span class="hlt">oceanic</span> lithosphere, long wavelength gravity anomalies, and seismic tomographic models show that this large upwelling reaches from Baffin Bay to Western Norway, and from offshore Newfoundland to Spitzbergen. At continental margins, there is excellent evidence for present-day dynamic support of crust beneath Scotland and Western Norway. It is generally agreed that the Icelandic Plume started at 62 Ma. In recent years, a quantitative understanding of the temporal evolution of this upwelling has begun to emerge. The best evidence occurs in the <span class="hlt">oceanic</span> basins north and south of Iceland. Since the mid-<span class="hlt">oceanic</span> ridge straddles the plume, it acts as a linear sampler of transient activity over the last 40-50 Ma. A pair of seismic reflection flowlines acquired in 2010 have enabled us to determine the detailed history of transient activity. The implications of this history are profound. Waxing and waning of convective upwelling beneath this important <span class="hlt">oceanic</span> gateway appears to have modulated the overflow of the ancient precursor to North <span class="hlt">Atlantic</span> Deep Water (NADW). The growth of contourite drifts which plaster deep-water margins can also be directly linked to changing vertical motions at this gateway. Finally, there is increasing evidence that the otherwise uniform thermal subsidence of sedimentary basins, which fringe both sides of the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, has been periodically interrupted by transient uplift events which generated ephemeral landscapes. These geologic manifestations of convective activity should lead to improved insights into the fluid dynamics of the mantle.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeoRL..41.6009F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeoRL..41.6009F"><span>Deep <span class="hlt">ocean</span> early warning signals of an <span class="hlt">Atlantic</span> MOC collapse</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Feng, Qing Yi; Viebahn, Jan P.; Dijkstra, Henk A.</p> <p>2014-08-01</p> <p>A future collapse of the <span class="hlt">Atlantic</span> Meridional Overturning Circulation (MOC) has been identified as one of the most dangerous tipping points in the climate system. It is therefore crucial to develop early warning indicators for such a potential collapse based on relatively short time series. So far, attempts to use indicators based on critical slowdown have been marginally successful. Based on complex climate network reconstruction, we here present a promising new indicator for the MOC collapse that efficiently monitors spatial changes in deep <span class="hlt">ocean</span> circulation. Through our analysis of the performance of this indicator, we formulate optimal locations of measurement of the MOC to provide early warning signals of a collapse. Our results imply that an increase in spatial resolution of the <span class="hlt">Atlantic</span> MOC observations (i.e., at more sections) can improve early detection, because the spatial coherence in the deep <span class="hlt">ocean</span> arising near the transition is better captured.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.A51D0075B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.A51D0075B"><span>Measurements of <span class="hlt">Ocean</span> Derived Aerosol Over the North <span class="hlt">Atlantic</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bates, T. S.; Quinn, P.; Frossard, A. A.; Russell, L. M.; Hakala, J. P.; Kieber, D. J.; Keene, W. C.</p> <p>2012-12-01</p> <p>Breaking waves on the <span class="hlt">ocean</span> surface inject sea spray particles into the atmosphere which can act as CCN. Characterization of particles freshly emitted from the <span class="hlt">ocean</span> surface requires a sampling method that is able to isolate those particles and prevent them from interacting with ambient gases and particles. Here we report measurements of particles directly emitted from the <span class="hlt">ocean</span> using a newly developed in-situ particle generator (Sea Sweep). The Sea Sweep was deployed alongside RV Ronald H. Brown in the North <span class="hlt">Atlantic</span> during August of 2012 in two contrasting regions; one in the eutrophic waters on Georges Bank and one in the oligotrophic waters near Bermuda. Bubbles were generated 0.75 m below the <span class="hlt">ocean</span> surface with stainless steel frits and swept into a hood/vacuum hose to feed a suite of aerosol instrumentation on board the ship. The measured aerosol properties from the two regions will be compared.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Ocgy...56..131D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Ocgy...56..131D"><span>Trace metal accumulation in carbonate biominerals of the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Demina, L. L.; Oskina, N. S.; Galkin, S. V.</p> <p>2016-01-01</p> <p>New data on trace metal (As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb) distribution in carbonate biominerals formed in geochemically different <span class="hlt">oceanic</span> environments are discussed. Calcite shells of shelf and deepwater hydrothermal vent mussels as well as planktic foraminifers and pteropods from the central <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> have been studied. The variability in concentrations of most trace elements between different groups of calcifying organisms are usually within one order of magnitude, except for Fe and Mn, the elevated contents of which in microfossils are caused by post-sedimentation interaction. Different groups of calcifying organisms demonstrate a biogeochemical uniformity in trace metal accumulation during the biomineralization processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4538673','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4538673"><span>Decadal acidification in the water masses of the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ríos, Aida F.; Resplandy, Laure; García-Ibáñez, Maribel I.; Fajar, Noelia M.; Velo, Anton; Padin, Xose A.; Wanninkhof, Rik; Steinfeldt, Reiner; Rosón, Gabriel; Pérez, Fiz F.</p> <p>2015-01-01</p> <p>Global <span class="hlt">ocean</span> acidification is caused primarily by the ocean’s uptake of CO2 as a consequence of increasing atmospheric CO2 levels. We present observations of the <span class="hlt">oceanic</span> decrease in pH at the basin scale (50°S–36°N) for the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> over two decades (1993–2013). Changes in pH associated with the uptake of anthropogenic CO2 (ΔpHCant) and with variations caused by biological activity and <span class="hlt">ocean</span> circulation (ΔpHNat) are evaluated for different water masses. Output from an Institut Pierre Simon Laplace climate model is used to place the results into a longer-term perspective and to elucidate the mechanisms responsible for pH change. The largest decreases in pH (∆pH) were observed in central, mode, and intermediate waters, with a maximum ΔpH value in South <span class="hlt">Atlantic</span> Central Waters of −0.042 ± 0.003. The ΔpH trended toward zero in deep and bottom waters. Observations and model results show that pH changes generally are dominated by the anthropogenic component, which accounts for rates between −0.0015 and −0.0020/y in the central waters. The anthropogenic and natural components are of the same order of magnitude and reinforce one another in mode and intermediate waters over the time period. Large negative ΔpHNat values observed in mode and intermediate waters are driven primarily by changes in CO2 content and are consistent with (i) a poleward shift of the formation region during the positive phase of the Southern Annular Mode in the South <span class="hlt">Atlantic</span> and (ii) an increase in the rate of the water mass formation in the North <span class="hlt">Atlantic</span>. PMID:26216947</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24989766','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24989766"><span>New lysianassoid amphipods from the north eastern <span class="hlt">atlantic</span> <span class="hlt">ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kaim-Malka, R A</p> <p>2014-06-25</p> <p>Two new lysianassoid amphipod species, Ambasia anophthalma n. sp. and Bathyamaryllis biscayensis n. sp., are described based on adult females collected in the North Eastern <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> (Bay of Biscay) by an autonomous bait system deployed on the sea bottom at a depth of 1460-1550 m. These two species are characterized by the absence of eyes (blind species). They belong to genera which include very few species.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25543573','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25543573"><span>Geographical distribution of pelagic decapod shrimp in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Judkins, David C</p> <p>2014-12-16</p> <p>Ninety-one species of pelagic decapod shrimp were identified in 938 midwater-trawl collections taken between 1963 and 1974 from the North and South <span class="hlt">Atlantic</span>. Distributional maps are provided for the most frequently occurring species. Nighttime abundance of most species was greatest within the upper 200 m. Degree of geographical overlap was estimated using the geometric mean of the proportion of joint occurrences with a value ≥ 0.5 deemed significant. Geographical distributions tended to be unique, and only 31 species had values ≥ 0.5 with one or more other species. Species within genera and within phylogenetic subgroups of Sergia were generally parapatric or partially overlapping in distribution. Five geographical groupings of co-occurring species across genera were identified: Subpolar-Temperate, Southern Hemisphere, Central, Tropical, Eastern Tropical and Western Tropical. The two species of the Southern Hemisphere group are circumpolar at temperate latitudes. The 12 species of the Central group occurred throughout the subtropical and tropical North and South <span class="hlt">Atlantic</span>. The eight species of the Tropical group occurred broadly across the <span class="hlt">equatorial</span> <span class="hlt">Atlantic</span> and Caribbean with ranges usually extending into the Gulf of Mexico and northward in the Gulf Stream. The two species of the Western Tropical group occurred most often in the western tropics, but there were scattered occurrences at subtropical latitudes. The four species of the Eastern Tropical group were endemic to the Mauritanian Upwelling and the Angola-Benguela Frontal zones off western Africa. Two of the three species in the Subpolar-Temperate group had bipolar distributions, and all three occurred in the Mediterranean and in the Mauritanian Upwelling zone. Most Central, Tropical and Western Tropical species were present in the in the Gulf of Mexico. The 10 species from the Mediterranean were a mixture of Subpolar-Temperate, Central and benthopelagic species. Patterns of distribution in <span class="hlt">Atlantic</span> pelagic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoRL..44.7909V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoRL..44.7909V"><span>Hiatus-like decades in the absence of <span class="hlt">equatorial</span> Pacific cooling and accelerated global <span class="hlt">ocean</span> heat uptake</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>von Känel, Lukas; Frölicher, Thomas L.; Gruber, Nicolas</p> <p>2017-08-01</p> <p>A surface cooling pattern in the <span class="hlt">equatorial</span> Pacific associated with a negative phase of the Interdecadal Pacific Oscillation is the leading hypothesis to explain the smaller rate of global warming during 1998-2012, with these cooler than normal conditions thought to have accelerated the <span class="hlt">oceanic</span> heat uptake. Here using a 30-member ensemble simulation of a global Earth system model, we show that in 10% of all simulated decades with a global cooling trend, the eastern <span class="hlt">equatorial</span> Pacific actually warms. This implies that there is a 1 in 10 chance that decadal hiatus periods may occur without the <span class="hlt">equatorial</span> Pacific being the dominant pacemaker. In addition, the global <span class="hlt">ocean</span> heat uptake tends to slow down during hiatus decades implying a fundamentally different global climate feedback factor on decadal time scales than on centennial time scales and calling for caution inferring climate sensitivity from decadal-scale variability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120009088','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120009088"><span>Coherent Multidecadal Atmospheric and <span class="hlt">Oceanic</span> Variability in the North <span class="hlt">Atlantic</span>: Blocking Corresponds with Warm Subpolar <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hakkinen, Sirpa M.; Rhines, P. B.; Worthen, D. L.</p> <p>2012-01-01</p> <p>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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>. This is evident in atmospheric reanalysis data, both modern and for the full 20th century. Blocking is approximately in phase with <span class="hlt">Atlantic</span> multidecadal <span class="hlt">ocean</span> variability (AMV). Wintertime atmospheric blocking involves a highly distorted jetstream, isolating large regions of air from the westerly circulation. It influences the <span class="hlt">ocean</span> 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 <span class="hlt">ocean</span> 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 <span class="hlt">Atlantic</span> variability covaries with distant AMOC fields: both these connections may express the global influence of the subpolar North <span class="hlt">Atlantic</span> <span class="hlt">ocean</span> on the global climate system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PalOc..31...81B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PalOc..31...81B"><span>Global change across the Oligocene-Miocene transition: High-resolution stable isotope records from IODP Site U1334 (<span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span>)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Beddow, Helen M.; Liebrand, Diederik; Sluijs, Appy; Wade, Bridget S.; Lourens, Lucas J.</p> <p>2016-01-01</p> <p>The Oligocene-Miocene transition (OMT) (~23 Ma) is interpreted as a transient global cooling event, associated with a large-scale Antarctic ice sheet expansion. Here we present a 2.23 Myr long high-resolution (~3 kyr) benthic foraminiferal oxygen and carbon isotope (δ18O and δ13C) record from Integrated <span class="hlt">Ocean</span> Drilling Program Site U1334 (eastern <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span>), covering the interval from 21.91 to 24.14 Ma. To date, five other high-resolution benthic foraminiferal stable isotope stratigraphies across this time interval have been published, showing a ~1‰ increase in benthic foraminiferal δ18O across the OMT. However, these records are still few and spatially limited and no clear understanding exists of the global versus local imprints. We show that trends and the amplitudes of change are similar at Site U1334 as in other high-resolution stable isotope records, suggesting that these represent global deep water signals. We create a benthic foraminiferal stable isotope stack across the OMT by combining Site U1334 with records from ODP Sites 926, 929, 1090, 1264, and 1218 to best approximate the global signal. We find that isotopic gradients between sites indicate interbasinal and intrabasinal variabilities in deep water masses and, in particular, note an offset between the <span class="hlt">equatorial</span> <span class="hlt">Atlantic</span> and the <span class="hlt">equatorial</span> Pacific, suggesting that a distinct temperature gradient was present during the OMT between these deep water masses at low latitudes. A convergence in the δ18O values between infaunal and epifaunal species occurs between 22.8 and 23.2 Ma, associated with the maximum δ18O excursion at the OMT, suggesting climatic changes associated with the OMT had an effect on interspecies offsets of benthic foraminifera. Our data indicate a maximum glacioeustatic sea level change of ~50 m across the OMT.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/244079','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/244079"><span>Terrigenous Fe input and biogenic sedimentation in the glacial and interglacial <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Murray, R.W.; Leinen, M.; Knowlton, C.W.</p> <p>1995-12-01</p> <p>This study was performed to determine the relationship of particulate iron from land erosion to the accumulation of biogenic matter in the <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span>. Sediment cores representing the last six glacial-interglacial cycles and previously published mineralogic records were used as data input. Total iron, terrigenous, and biogenic components were determined for three sediment cores. The study determined that there is no relationship between terrigenous iron input and sedimentary carbon sequestering. This is based on chemical, spectral, and stratigraphic anlyses which showed: (1) no consistent pattern of terrigenous input during glacial or interglacial periods, (2) a close relationshipe between the accumulation of particulate iron and the accumulation of terrigenous matter, (3) no coherent spectral correlations between glacial periodicity and iron input, (4) an inverse correlation of iron input and calcium carbonate, and (5) no spectral or linear relationship between iron accumulation and calcium carbonate, organic carbon, or opal. 55 refs., 6 figs., 3 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMOS53C1704L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMOS53C1704L"><span>Dissolved and Particulate 230Th - 232Th systematics in the Central <span class="hlt">Equatorial</span> Pacific <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lopez, G. I.; Marcantonio, F.</p> <p>2013-12-01</p> <p>To complement our work in the eastern <span class="hlt">Equatorial</span> Pacific, we have measured total and dissolved 230Th and 232Th in the central <span class="hlt">Equatorial</span> Pacific at two sites, one at 8°N and the other at the equator (ML1208-03CTD; 00° 13.166' S, 155° 57.668' W and ML1208-12CTD; 8° 19.989' N, 159° 18.000' W). The two seawater casts were collected in May 2012 during an NSF-funded "Line Islands" cruise to test for the extent of advection or diffusion of dissolved 230Th from the oligotrophic North Pacific gyre (low particle flux) to the more productive <span class="hlt">equatorial</span> region (high particle flux). Our thorium results are similar to previous data published for the western and central North Pacific <span class="hlt">Ocean</span>. Dissolved 230Th concentrations range from 1.1 fg/kg at 100 m to 30.8 fg/kg at 4400 m, while dissolved 232Th concentrations span from 8.1 pg/kg at 900 m to 19.7 pg/kg at 4400 m. The pattern of the dissolved 230Th profile at 8°N is essentially linear from the surface to 2000 m. From 2000 m to 3000 m, the dissolved 230Th concentrations are constant, and then from 3000 m to the bottom, the profile is linear again. At the same site, the particulate fraction of the total seawater 230Th increases exponentially from about 0% at the surface to 38% at 4400 m. From 0 to 3000 m at 8°N, dissolved 232Th concentrations display a relatively constant pattern (variability of about 20%). From 3000 m to 4400 m, dissolved 232Th contents are more variable, but generally increase toward greater depths. The proportion of 232Th in the particulate fraction of the total seawater sample increases exponentially with depth to a value of 58% in the bottommost sample. We will present additional data from the equator and assess the particulate dynamics that control the distribution of thorium isotopes in central <span class="hlt">equatorial</span> Pacific seawater.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950049301&hterms=photograph&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dphotograph','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950049301&hterms=photograph&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dphotograph"><span>Dynamic interpretation of space shuttle photographs: Deepwater internal waves in the western <span class="hlt">equatorial</span> Indian <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zheng, Quanan; Klemas, Vic; Yan, Xiao-Hai</p> <p>1995-01-01</p> <p>Visible images of deep-<span class="hlt">ocean</span> internal waves in the western <span class="hlt">equatorial</span> Indian <span class="hlt">Ocean</span> taken by the space shuttle Atlantis during mission STS 44 in 1991 are interpreted and analyzed. The internal waves occurred in the form of a multisoliton packet in which there are about a dozen solitons. The average wavelength of the solitons is 1.8 +/- 0.5 km, ranging from 1.1 to 2.6 km. The crest lines are mostly straight and reach as long as 100 km. The distance between two adjacent packets is about 66 km. Using the deepwater soliton theory, we derived that the mean amplitude of the solitons is 25 m, the nonlinear phase speed is 1.7 m/s, and the average period is 18 min. The internal semidiurnal tides are the principal generating mechanism. The oblique collision of two multisoliton packets shown on photograph STS 44-93-103 is examined. The results show that the deep-<span class="hlt">ocean</span> internal waves obey the general properties of soliton collision. The leading solitons and a few followers exhibit some properties of inelastic collision characterized by a phase shift, and the rest of the solitons exhibits properties of elastic collision under resonance conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012NatGe...5..270M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012NatGe...5..270M"><span>Links between iron input and opal deposition in the Pleistocene <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Murray, Richard W.; Leinen, Margaret; Knowlton, Christopher W.</p> <p>2012-04-01</p> <p>Increases in overall marine primary productivity and export production in high-nutrient, low-chlorophyll regions of the <span class="hlt">ocean</span> have, particularly during dry and dusty glacial periods, been hypothesized to be linked to the enhanced delivery of iron. In the modern <span class="hlt">ocean</span>, iron availability limits production in high-nutrient, low-chlorophyll regions, and may be important in lower-nutrient settings as well. Here, we assess the relationship between productivity and iron in sedimentary records from the high-nutrient, low-chlorophyll region of the <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span> over the past million years. We find strong links between iron input, the export and burial of biogenic silica (opal) and total export production. Our data demonstrate that iron accumulation was more closely tied to the accumulation of opal than any other biogenic component, with high iron input associated with substantially increased opal sedimentation. The strong links between iron and opal accumulation over the past one million years are in agreement with the modern biogeochemical behaviour of iron and silica, and the response of the diatom community to their mutual availablity. Our data support earlier suggestions of a biological response to iron delivery over geologic timescales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996Natur.383..508B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996Natur.383..508B"><span>Confirmation of iron limitation of phytoplankton photosynthesis in the <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Behrenfeld, Michael J.; Bale, Anthony J.; Kolber, Zbigniew S.; Aiken, James; Falkowski, Paul G.</p> <p>1996-10-01</p> <p>THE eastern <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span> is one of only three open-<span class="hlt">ocean</span> regions where low phytoplankton chlorophyll biomass persists despite perennially high nitrate and phosphate nutrient concentrations1. In 1993, an area within this region was artificially enriched with a single dose of soluble iron to test whether phytoplankton are physiologically prevented from utilizing the available nutrients by the low natural iron concentrations2,3. Although photosynthesis was stimulated4, the observed lack of a bloom or a significant decrease in nutrient concentrations could not be attributed unequivocally to zooplankton grazing5-7, further iron limitation or secondary nutrient limitation2,4. In 1995, a second iron-enrichment experiment (IronEx II) was conducted in which the same total dosage of iron was added, but over eight days8. A massive phytoplankton bloom developed, significantly reducing surface-water nutrient and CO2 concentrations8-10. Here we report in situ measurements of fluorescence during IronEx II, which show that the iron enrichment triggered biophysical alterations of the phytoplankton's photosynthetic apparatus, resulting in increased photosynthetic capacities throughout the experiment and, hence, the observed bloom. These results unequivocally establish physiological limitation of phytoplankton by iron as the cause of the high-nitrate, low-chlorophyll phenomenon in this <span class="hlt">ocean</span> region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.B23B0393G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.B23B0393G"><span><span class="hlt">Oceanic</span> δ15N biogeography: a novel top-down approach to examine nutrient dynamics in the <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Graham, B. S.; Fry, B.; Popp, B. N.; Allain, V.; Olson, R.; Galvan, F.</p> <p>2010-12-01</p> <p>By mapping the δ15N and δ13C values of three top-level pelagic predators, yellowfin (Thunnus albacares), bigeye (T. obesus), and skipjack (Katsuwonus pelamis) tuna throughout the <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span>, we demonstrated systematic geographic isotopic variation (up to ~12‰ for the δ15N values) that reflect nutrient dynamics that occur at the base of the food web. Remarkably the variation observed in the δ15N values of the tunas is geographically similar to δ15N values previously reported in surface particulate organic matter and deep-sea sediments in the tropical Pacific. We discuss the mechanisms occurring at the base of the food web that could produce the spatial variability observed in tropical tuna δ15N values. We present a simple Rayleigh fractionation model that can explain much of the spatial structure. We also discuss the temporal stability in the isotopic compositions at the base and top of the food web. Overall, this nitrogen isotope cartography or “isoscapes” suggests nitrogen is tightly retained in the marine food web, up to the top predators, and that the uptake of nitrate from the <span class="hlt">equatorial</span> upwelling zone, denitrification in the oxygen minimum zones, and nitrogen fixation at the base of the food web play major roles in the observed geographical variation. In addition to providing insight into the nutrient dynamics of the open <span class="hlt">ocean</span>, these predator isoscapes can begin to be used to characterize regional residency in tropical tunas, which is important for the successful management of tuna fisheries.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004GMS...147..121X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004GMS...147..121X"><span>Tropical <span class="hlt">Atlantic</span> variability: Patterns, mechanisms, and impacts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xie, Shang-Ping; Carton, James A.</p> <p></p> <p>This chapter reviews the progress made in the past decade in understanding tropical <span class="hlt">Atlantic</span> climate variability. In addition to an <span class="hlt">equatorially</span> anti-symmetric seasonal cycle forced directly by the seasonal march of the sun, <span class="hlt">Atlantic</span> sea surface temperature (SST) displays a pronounced annual cycle on the equator that results from continental monsoon forcing and air-sea interaction. This cycle interacts with and regulates the meridional excursions of the <span class="hlt">Atlantic</span> intertropical convergence zone (ITCZ). On interannual timescales, there is an <span class="hlt">equatorial</span> mode of variability that is similar to El Niño/Southern Oscillation (ENSO) in the Pacific. This <span class="hlt">Atlantic</span> Niño is most pronounced in boreal summer coinciding with the seasonal development of the <span class="hlt">equatorial</span> cold tongue. In boreal winter, both ENSO and the North <span class="hlt">Atlantic</span> Oscillation exert a strong influence on the northeast trades and SST over the northern tropical <span class="hlt">Atlantic</span>. In boreal spring when the <span class="hlt">equatorial</span> <span class="hlt">Atlantic</span> is uniformly warm, anomalies of cross-<span class="hlt">equatorial</span> SST gradient and the ITCZ are closely coupled, resulting in anomalous rainfall over northeastern Brazil. There is evidence for a positive air-sea feedback through wind-induced surface evaporation that organizes off-<span class="hlt">equatorial</span> SST anomalies to maximize their cross-<span class="hlt">equatorial</span> gradient. The resultant anomalous shift of the ITCZ may affect the North <span class="hlt">Atlantic</span> Oscillation, helping to organize <span class="hlt">ocean</span>-atmospheric anomalies into a pan-<span class="hlt">Atlantic</span> pattern.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1916835I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1916835I"><span>Subseasonal Coastal Trapped Waves propagation in the Southeastern <span class="hlt">Atlantic</span> and Pacific <span class="hlt">Oceans</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Illig, Serena; Cadier, Emeline; Bachèlery, Marie-Lou; Dewitte, Boris</p> <p>2017-04-01</p> <p>The objective of this study is to describe the Coastal Trapped Wave variability along the southwestern American and African continents at subseasonal timescales (<120 days). We aim at determining to which extent the alongshore current and sea level coastal variability can be accounted for by <span class="hlt">equatorially</span> remote-forced or locally wind-forced CTW response. The methodology is based on the experimentation with twin regional model configurations of the South Eastern Pacific and the South Eastern <span class="hlt">Atlantic</span> <span class="hlt">oceans</span>. The estimation of free CTW modal structures and associated contribution to coastal variability allows to infer and compare the characteristics (magnitude, dissipation, scattering) of each CTW mode in the two systems, in order to explain their similarities and differences at subseasonal time scales as observed from altimetry. The modal structures of the four first free CTW modes are first derived from model mean stratification and topography, at all cross-shore sections along the South Western African and American continents. In the Humboldt Current system, the CTW structures are significantly more baroclinic than in the Benguela, due to steeper and deeper topographic slope along the Peruvian and Chilean coasts. We then developed a new methodology to estimate the CTW contributions to model pressure and alongshore currents. In both systems, the extracted modes of variability are shown to propagate at velocities close to the appropriate theoretical phase speeds. The summed-up contribution of the first three CTW modes account for 60% of the subseasonal variance in along-shelf currents on the shelf and slope and 80% of the coastal sea level variability. In the <span class="hlt">Atlantic</span> southeastern basin, mode 2 carries a greater fraction of CTW energy than mode 1, while in the Pacific counterpart it is the inverse. Mode 1 and mode 2 contributions are not coherent in time and exhibits particular space-time characteristics. Numerical sensitivity experiments allow to quantify the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996Natur.383..495C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996Natur.383..495C"><span>A massive phytoplankton bloom induced by an ecosystem-scale iron fertilization experiment in the <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Coale, Kenneth H.; Johnson, Kenneth S.; Fitzwater, Steve E.; Gordon, R. Michael; Tanner, Sara; Chavez, Francisco P.; Ferioli, Laurie; Sakamoto, Carole; Rogers, Paul; Millero, Frank; Steinberg, Paul; Nightingale, Phil; Cooper, David; Cochlan, William P.; Landry, Michael R.; Constantinou, John; Rollwagen, Gretchen; Trasvina, Armando; Kudela, Raphael</p> <p>1996-10-01</p> <p>The seeding of an expanse of surface waters in the <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span> with low concentrations of dissolved iron triggered a massive phytoplankton bloom which consumed large quantities of carbon dioxide and nitrate that these microscopic plants cannot fully utilize under natural conditions. These and other observations provide unequivocal support for the hypothesis that phytoplankton growth in this <span class="hlt">oceanic</span> region is limited by iron bioavailability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSED24A1653K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSED24A1653K"><span>Using <span class="hlt">Ocean</span> Exploration in the <span class="hlt">Atlantic</span> Canyons to Advance Conversations about Transatlantic <span class="hlt">Ocean</span> Literacy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Keener, P.; Tuddenham, P. T.; Bishop, T.</p> <p>2016-02-01</p> <p>The National <span class="hlt">Oceanic</span> 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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, 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 <span class="hlt">ocean</span> educators and the public were able to observe via telepresence the deep <span class="hlt">Atlantic</span> using NOAA's new remotely-operated vehicle Deep Discoverer. In a collaboration between the NOAA Office of <span class="hlt">Ocean</span> 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 <span class="hlt">Atlantic</span> Onboard the NOAA Ship Okeanos Explorer…Online Conversations to Advance Transatlantic <span class="hlt">Ocean</span> Literacy, built upon the telepresence experience and served as a foundation for extending conversations begun approximately a year earlier on transatlantic <span class="hlt">ocean</span> 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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>." 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 <span class="hlt">ocean</span> literacy and scientific understanding in support of The Galway Statement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMPP13E..01L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMPP13E..01L"><span>Holocene changes in eastern <span class="hlt">equatorial</span> <span class="hlt">Atlantic</span> salinity as estimated by water isotopologues</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Leduc, G.; Sachs, J. P.; Kawka, O.; Schneider, R. R.</p> <p>2011-12-01</p> <p>The Holocene tropical North African monsoon evolution was controlled at first order by insolation, but the timing and trends of paleo-records sensitive to precipitation substantially differ upon proxies and locations. Salinity reconstructions based on Ba/Ca and δ18Osw from one marine sediment core recovered from the eastern <span class="hlt">equatorial</span> <span class="hlt">Atlantic</span> close to the Niger River mouth integrate rainfall changes over the river catchment located in the northern tropics, and indicate that the region was wetter during the mid-Holocene relative to the present (Weldeab et al., 2007). A closer look those salinity reconstructions which are derived from the same sedimentary sequence however indicates divergent salinity trends as estimated by Ba/Ca and δ18Osw for the late Holocene (Weldeab et al., 2007). In order to refine better the past changes in the regional hydrologic cycle, we have reevaluated salinity records by measuring δD of C37:2 alkenones from the same sedimentary sequence. A smooth, long-term increase of ~10% in δD between 10 and 3 kyr BP is followed by an equivalent but more rapid decrease between 3 kyr BP and core top, where the δD values are slightly lighter than during the early Holocene. Both δ18Osw and alkenone δD suggest a late Holocene sea surface salinity decrease based on the modern relationship between salinity and isotopic composition of seawater, and this result differs from the salinity record derived from Ba/Ca. We apply the method for reconstructing salinity using water isotopologues described in Rohling (2007) and in LeGrande and Schmidt (2011). The new salinity record derived from paired δ18Osw and alkenone δD modifies the salinity trends as estimated by oxygen and deuterium isotopic ratios alone and indicates monotonous salinity increases over the last 7 ka. This result is in better agreement with both the Ba/Ca salinity record and a pollen record from the Lake M'Balang (Cameroon) which reveals a progressive dessication in the region over the</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016E%26ES...34a2008F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016E%26ES...34a2008F"><span>Monitoring the North <span class="hlt">Atlantic</span> using <span class="hlt">ocean</span> colour data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fuentes-Yaco, C.; Caverhill, C.; Maass, H.; Porter, C.; White, GN, III</p> <p>2016-04-01</p> <p>The Remote Sensing Unit (RSU) at the Bedford Institute of Oceanography (BIO) has been monitoring the North <span class="hlt">Atlantic</span> using <span class="hlt">ocean</span> colour products for decades. Optical sensors used include CZCS, POLDER, SeaWiFS, MODIS/Aqua and MERIS. The monitoring area is defined by the <span class="hlt">Atlantic</span> 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 <span class="hlt">ocean</span> 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 (<span class="hlt">Ocean</span> Land Colour Instrument), and PACE (Pre-Aerosol, Clouds and <span class="hlt">ocean</span> Ecosystem) hyperspectral microsatellite mission.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1714851R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1714851R"><span>Surface salinity variability in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> (50°N-10°S) at pluri-annual to interdecadal time scales (1896-2013)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reverdin, Gilles; Kestenare, ELodie; Delcroix, Thierry; ALory, Gael; Boutin, Jacqueline; Gaillard, Fabienne; Martin, Nicolas</p> <p>2015-04-01</p> <p>Surface salinity data have been collected across the north and tropical <span class="hlt">Atlantic</span> often by ships of opportunity (SOP) since the mid-1890s. Until the 1950s and even for some regions after, this SOP remains the main source of knowledge on past surface salinity variability Iin this <span class="hlt">ocean</span>. Ship-of-opportunitySOP surface sampling has continued afterwards and up to now, either from buckets or since the 1990s from thermosalinographs, but in parallel with other means of collections, including station bottles, CTD casts, or more recently profiling floats. We will present to which extent these different sets are consistent and with which accuracy. An attempt to reconstruct past pluri-annual variability over vast sub-regions of the <span class="hlt">Atlantic</span>, mostly north of 10°S was is then made for the period 1896 to 2013. It often portrays rather similar pluri-annual variability in the different seasons, as we earlier found in the subpolar North <span class="hlt">Atlantic</span>. The pluri-annual deviations from the seasonal cycle are rather different between the <span class="hlt">equatorial</span>, the subtropical North <span class="hlt">Atlantic</span>, and further north at mid latitudes between eastern and western <span class="hlt">Atlantic</span>. Pluri-decadal variability seems prominent in most of these regions, and seems unlikely to have originated from residual biases in some of the subsets. When combining data from these different regions, thus through the whole North and <span class="hlt">equatorial</span> <span class="hlt">Atlantic</span>, there is no significant trend that emerges . Comparisons with SST evolution will be made, in particular for pluri-decennal variability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3578572','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3578572"><span>Gradients in microbial methanol uptake: productive coastal upwelling waters to oligotrophic gyres in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dixon, Joanna L; Sargeant, Stephanie; Nightingale, Philip D; Colin Murrell, J</p> <p>2013-01-01</p> <p>Methanol biogeochemistry and its importance as a carbon source in seawater is relatively unexplored. We report the first microbial methanol carbon assimilation rates (k) in productive coastal upwelling waters of up to 0.117±0.002 d−1 (∼10 nmol l−1 d−1). On average, coastal upwelling waters were 11 times greater than open <span class="hlt">ocean</span> northern temperate (NT) waters, eight times greater than gyre waters and four times greater than <span class="hlt">equatorial</span> upwelling (EU) waters; suggesting that all upwelling waters upon reaching the surface (⩽20 m), contain a microbial population that uses a relatively high amount of carbon (0.3–10 nmol l−1 d−1), derived from methanol, to support their growth. In open <span class="hlt">ocean</span> <span class="hlt">Atlantic</span> regions, microbial uptake of methanol into biomass was significantly lower, ranging between 0.04–0.68 nmol l−1 d−1. Microbes in the Mauritanian coastal upwelling used up to 57% of the total methanol for assimilation of the carbon into cells, compared with an average of 12% in the EU, and 1% in NT and gyre waters. Several methylotrophic bacterial species were identified from open <span class="hlt">ocean</span> <span class="hlt">Atlantic</span> waters using PCR amplification of mxaF encoding methanol dehydrogenase, the key enzyme in bacterial methanol oxidation. These included Methylophaga sp., Burkholderiales sp., Methylococcaceae sp., Ancylobacter aquaticus, Paracoccus denitrificans, Methylophilus methylotrophus, Methylobacterium oryzae, Hyphomicrobium sp. and Methylosulfonomonas methylovora. Statistically significant correlations for upwelling waters between methanol uptake into cells and both chlorophyll a concentrations and methanol oxidation rates suggest that remotely sensed chlorophyll a images, in these productive areas, could be used to derive total methanol biological loss rates, a useful tool for atmospheric and marine climatically active gas modellers, and air–sea exchange scientists. PMID:23178665</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23178665','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23178665"><span>Gradients in microbial methanol uptake: productive coastal upwelling waters to oligotrophic gyres in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dixon, Joanna L; Sargeant, Stephanie; Nightingale, Philip D; Colin Murrell, J</p> <p>2013-03-01</p> <p>Methanol biogeochemistry and its importance as a carbon source in seawater is relatively unexplored. We report the first microbial methanol carbon assimilation rates (k) in productive coastal upwelling waters of up to 0.117±0.002 d(-1) (~10 nmol l(-1 )d(-1)). On average, coastal upwelling waters were 11 times greater than open <span class="hlt">ocean</span> northern temperate (NT) waters, eight times greater than gyre waters and four times greater than <span class="hlt">equatorial</span> upwelling (EU) waters; suggesting that all upwelling waters upon reaching the surface (≤20 m), contain a microbial population that uses a relatively high amount of carbon (0.3-10 nmol l(-1 )d(-1)), derived from methanol, to support their growth. In open <span class="hlt">ocean</span> <span class="hlt">Atlantic</span> regions, microbial uptake of methanol into biomass was significantly lower, ranging between 0.04-0.68 nmol l(-1 )d(-1). Microbes in the Mauritanian coastal upwelling used up to 57% of the total methanol for assimilation of the carbon into cells, compared with an average of 12% in the EU, and 1% in NT and gyre waters. Several methylotrophic bacterial species were identified from open <span class="hlt">ocean</span> <span class="hlt">Atlantic</span> waters using PCR amplification of mxaF encoding methanol dehydrogenase, the key enzyme in bacterial methanol oxidation. These included Methylophaga sp., Burkholderiales sp., Methylococcaceae sp., Ancylobacter aquaticus, Paracoccus denitrificans, Methylophilus methylotrophus, Methylobacterium oryzae, Hyphomicrobium sp. and Methylosulfonomonas methylovora. Statistically significant correlations for upwelling waters between methanol uptake into cells and both chlorophyll a concentrations and methanol oxidation rates suggest that remotely sensed chlorophyll a images, in these productive areas, could be used to derive total methanol biological loss rates, a useful tool for atmospheric and marine climatically active gas modellers, and air-sea exchange scientists.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA526502','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA526502"><span>Near-Inertial and Thermal Upper <span class="hlt">Ocean</span> Response to Atmospheric Forcing in the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2010-06-01</p> <p>water is then subducted as the <span class="hlt">ocean</span> restratifies during spring, and advected throughout the subtropical gyre by the large scale wind driven circulation...Luther, and W. C. Patzert, 1992: The heat budget in the north <span class="hlt">atlantic</span> subtropical frontal zone . J. Geophys. Res., 97 (C11), 17 947–17 959. 131 Price, J</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050160237','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050160237"><span><span class="hlt">Oceanic</span> Situational Awareness over the North <span class="hlt">Atlantic</span> Corridor</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Welch, Bryan; Greenfield, Israel</p> <p>2005-01-01</p> <p>Air traffic control (ATC) mandated, aircraft separations over the <span class="hlt">oceans</span> impose a limitation on traffic capacity for a given corridor, given the projected traffic growth over the <span class="hlt">oceanic</span> domain. The separations result from a lack of acceptable situational awareness over <span class="hlt">oceans</span> 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 <span class="hlt">Atlantic</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ClDy..tmp..219S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ClDy..tmp..219S"><span>Association between mean and interannual <span class="hlt">equatorial</span> Indian <span class="hlt">Ocean</span> subsurface temperature bias in a coupled model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Srinivas, G.; Chowdary, Jasti S.; Gnanaseelan, C.; Prasad, K. V. S. R.; Karmakar, Ananya; Parekh, Anant</p> <p>2017-05-01</p> <p>In the present study the association between mean and interannual subsurface temperature bias over the <span class="hlt">equatorial</span> Indian <span class="hlt">Ocean</span> (EIO) is investigated during boreal summer (June through September; JJAS) in the National Centers for Environmental Prediction (NCEP) Climate Forecast System (CFSv2) hindcast. Anomalously high subsurface warm bias (greater than 3 °C) over the eastern EIO (EEIO) region is noted in CFSv2 during summer, which is higher compared to other parts of the tropical Indian <span class="hlt">Ocean</span>. Prominent eastward current bias in the upper 100 m over the EIO region induced by anomalous westerly winds is primarily responsible for subsurface temperature bias. The eastward currents transport warm water to the EEIO and is pushed down to subsurface due to downwelling. Thus biases in both horizontal and vertical currents over the EIO region support subsurface warm bias. The evolution of systematic subsurface warm bias in the model shows strong interannual variability. These maximum subsurface warming episodes over the EEIO are mainly associated with La Niña like forcing. Strong convergence of low level winds over the EEIO and Maritime continent enhanced the westerly wind bias over the EIO during maximum warming years. This low level convergence of wind is induced by the bias in the gradient in the mean sea level pressure with positive bias over western EIO and negative bias over EEIO and parts of western Pacific. Consequently, changes in the atmospheric circulation associated with La Niña like conditions affected the <span class="hlt">ocean</span> dynamics by modulating the current bias thereby enhancing the subsurface warm bias over the EEIO. It is identified that EEIO subsurface warming is stronger when La Niña co-occurred with negative Indian <span class="hlt">Ocean</span> Dipole events as compared to La Niña only years in the model. <span class="hlt">Ocean</span> general circulation model (OGCM) experiments forced with CFSv2 winds clearly support our hypothesis that <span class="hlt">ocean</span> dynamics influenced by westerly winds bias is primarily</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25008528','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25008528"><span>Quantification of dissolved iron sources to the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Conway, Tim M; John, Seth G</p> <p>2014-07-10</p> <p>Dissolved iron is an essential micronutrient for marine phytoplankton, and its availability controls patterns of primary productivity and carbon cycling throughout the <span class="hlt">oceans</span>. The relative importance of different sources of iron to the <span class="hlt">oceans</span> is not well known, however, and flux estimates from atmospheric dust, hydrothermal vents and <span class="hlt">oceanic</span> sediments vary by orders of magnitude. Here we present a high-resolution transect of dissolved stable iron isotope ratios (δ(56)Fe) and iron concentrations ([Fe]) along a section of the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>. The different iron sources can be identified by their unique δ(56)Fe signatures, which persist throughout the water column. This allows us to calculate the relative contribution from dust, hydrothermal venting and reductive and non-reductive sedimentary release to the dissolved phase. We find that Saharan dust aerosol is the dominant source of dissolved iron along the section, contributing 71-87 per cent of dissolved iron. Additional sources of iron are non-reductive release from oxygenated sediments on the North American margin (10-19 per cent), reductive sedimentary dissolution on the African margin (1-4 per cent) and hydrothermal venting at the Mid-<span class="hlt">Atlantic</span> Ridge (2-6 per cent). Our data also indicate that hydrothermal vents in the North <span class="hlt">Atlantic</span> are a source of isotopically light iron, which travels thousands of kilometres from vent sites, potentially influencing surface productivity. Changes in the relative importance of the different iron sources through time may affect interactions between the carbon cycle and climate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70010929','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70010929"><span>Suspended particulate loads and transports in the nepheloid layer of the abyssal <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Biscaye, P.E.; Eittreim, S.L.</p> <p>1977-01-01</p> <p>Vertical profiles of light scattering from over 1000 L-DGO nephelometer stations in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> have been used to calculate mass concentrations of suspended particles based on a calibration from the western North American Basin. From these data are plotted the distributions of particulate concentrations at clear water and in the more turbid near-bottom water. Clear water is the broad minimum in concentration and light scattering that occurs at varying mid-depths in the water column. Concentrations at clear water are as much as one-to-two orders of magnitude lower than those in surface water but still reflect a similar geographic distribution: relatively higher concentrations at <span class="hlt">ocean</span> margins, especially underneath upwelling areas, and the lowest concentrations underneath central gyre areas. These distributions within the clear water reflect surface-water biogenic productivity, lateral injection of particles from shelf areas and surface circulation patterns and require that the combination of downward vertical and horizontal transport processes of particles retain this pattern throughout the upper water column. Below clear water, the distribution of standing crops of suspended particulate concentrations in the lower water column are presented. The integration of mass of all particles per unit area (gross particulate standing crop) reflects a relative distribution similar to that at the surface and at clear water levels, superimposed on which is the strong imprint of boundary currents along the western margins of the <span class="hlt">Atlantic</span>. Reducing the gross particulate standing crop by the integral of the concentration of clear water yields a net particulate standing crop. The distribution of this reflects primarily the interaction of circulating abyssal waters with the <span class="hlt">ocean</span> bottom, i.e. a strong nepheloid layer which is coincident with western boundary currents and which diminishes in intensity equatorward. The resuspended particulate loads in the nepheloid layer of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26624302','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26624302"><span>Fennerosquilla heptacantha (Crustacea: Stomatopoda: Squillidae) in South <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lucatelli, Débora</p> <p>2015-10-07</p> <p>Fennerosquilla is a monotypic genus that belongs to the family Squillidae, which has the highest generic diversity within Stomatopoda. This genus has been recorded in the north <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, the Gulf of Mexico and Caribbean Sea, between 105 and 458 m depth. The present specimen was collected during the project "Avaliação da Biota Bentônica e Planctônica na porção offshore das Bacias Potiguar e Ceará", in 2011, from the continental slope region of Brazil. In this expedition Fennerosquilla heptacantha was found at 178-193 m depth, and represents the first record of the species in the south <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> (Rio Grande do Norte State, northeastern Brazil), expanding the southern limit distribution. The specimen is the largest recorded, measuring 149 mm total length. The pigmentation zone on median region of telson and all diagnostic characters are still preserved and agree with the original description. Fennerosquilla heptacantha has a disjunct deep water distribution (more than 100 m) in the tropical western <span class="hlt">Atlantic</span>, mostly along the continental slope.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007GBioC..21.2006M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007GBioC..21.2006M"><span><span class="hlt">Atlantic</span> Southern <span class="hlt">Ocean</span> productivity: Fertilization from above or below?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meskhidze, Nicholas; Nenes, Athanasios; Chameides, William L.; Luo, Chao; Mahowald, Natalie</p> <p>2007-06-01</p> <p>Primary productivity and the associated uptake of atmospheric carbon dioxide in the Southern <span class="hlt">Ocean</span> (SO) is thought to be generally limited by bioavailable iron (Fe). Two sources of Fe for the surface waters of the SO have been proposed: (1) <span class="hlt">oceanic</span> input of nutrient-rich (i.e., Fe) waters from upwelling and lateral flows from continental margins; and (2) atmospheric input from the deposition of mineral dust emanating from the arid regions of South America and Australia. In this work, analysis of weekly remotely sensed sea surface temperature (SST), <span class="hlt">ocean</span> chlorophyll a content [Chl a] and model-derived atmospheric dust-Fe fluxes are used to identify the predominant source of Fe during phytoplankton blooms in the surface waters of the south <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> between 40°S and 60°S. The results of our study suggest that <span class="hlt">oceanic</span> source through upwelling of nutrient-rich waters due to mesoscale frontal dynamics is the major source of bioavailable Fe controlling biological activity in this region. This result is consistent with the idea that acidification of aeolian dust prior to its deposition to the <span class="hlt">ocean</span> may be required to solubilize the large fraction of mineral-iron and make it bioavailable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMPP41B2229R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMPP41B2229R"><span>Influence of Southern <span class="hlt">Ocean</span> Intermediate Water on productivity in the eastern <span class="hlt">equatorial</span> Pacific on orbital timescale</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rippert, N.; Max, L.; Tiedemann, R.; Cacho Lascorz, I.; Mackensen, A.</p> <p>2015-12-01</p> <p>The eastern <span class="hlt">equatorial</span> Pacific (EEP) is one of the key areas for studying <span class="hlt">oceanic</span> processes that control atmospheric CO2 concentrations. Southern-sourced water masses (SOIW) are thought to stimulate the biological pump in the EEP and hence contributed to the CO2 drawdown during glacial times. Orbital forcing in combination with local feedback mechanisms are assumed to be the main driver for this water mass advection. Newest studies, however, question the capability of SOIW to stimulate primary productivity during Marine Isotope Stage 2 (MIS2), as nutrients are rather utilized in the Southern <span class="hlt">Ocean</span>. Instead, nutrient-rich Glacial North Pacific Intermediate Waters (GNPIW) seem to be a major component of water masses upwelled in the EEP to enhance productivity in the EEP during MIS2. We present changes in biological productivity in the EEP over the last 190 ka derived from surface-dwelling planktic foraminifera Globigerinoides ruber and deep-dwelling planktic foraminifera Globorotaloides hexagonus (ODP Site 1240). The δ13C gradient between surface and sub-thermocline (Δδ13Crub-hex) has been used to assess export production in that area. We compare this with variations in the nutrient gradient (Δδ13Chex-SOIW) between sub-thermocline <span class="hlt">equatorial</span> waters (~350 m) and SOIW. The Δδ13Chex-SOIW variability is dominated by 100 kyr and 23 kyr cycles. This implies a strong response to changes in orbital precession and internal climate forcing related to major changes in ice volume. At times of low precession the difference between the nutrient concentrations of EEP waters and nutrients delivered via SOIW differ substantially, thus indicating that SOIW is not providing sufficient nutrients to stimulate productivity in the EEP. This scenario is most prominent during MIS2 and MIS6. Following the interpretation by Max et al. (submitted) we speculate that similar to MIS2, nutrients were trapped in the Southern <span class="hlt">Ocean</span> also during MIS6 leaving northward-advected SOIW rather</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010E%26PSL.297..355L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010E%26PSL.297..355L"><span>An alternative early opening scenario for the Central <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Labails, Cinthia; Olivet, Jean-Louis; Aslanian, Daniel; Roest, Walter R.</p> <p>2010-09-01</p> <p>The opening of the Central <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> 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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>. 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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> 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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> is described in four distinct phases. During the first 20 Myr after the initial breakup (190-170 Ma, from Late Sinemurian to early Bajocian), <span class="hlt">oceanic</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMPP21E..04D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMPP21E..04D"><span>Glacial deep <span class="hlt">ocean</span> sequestration of CO2 driven by the eastern <span class="hlt">equatorial</span> Pacific biologic pump</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Doss, W. C.; Marchitto, T. M.</p> <p>2013-12-01</p> <p>The potential influence of low latitude <span class="hlt">ocean</span> primary productivity on glacial atmospheric carbon dioxide levels has proven challenging to deduce using mass accumulation rates (MARs) of biogenic particulates in deep sea sediment cores. Benthic foraminiferal B/Ca serves as a proxy for past seawater calcite saturation state,and thereby provides a fresh perspective on this outstanding paleoceanographic problem. Here we employ Cibicidoides wuellerstorfi B/Ca in the Panama Basin region of the eastern <span class="hlt">equatorial</span> Pacific (EEP) to investigate the nature of deep tropical Pacific carbon storage over the past 50 ka BP. We present evidence for persistently lower deep Panama Basin calcite saturation state, reflecting an increase in total carbon dioxide storage, during the last ice age relative to the Holocene. These results reflect the modification of inflowing deep waters by overlying export productivity, and support the concept of an invigorated glacial EEP soft-tissue pump possibly driven by <span class="hlt">oceanic</span> nutrient (iron and silica) redistribution. Benthic Cibicidoides spp. carbon-13 is consistent with this conclusion by exhibiting substantially lighter values during glacial time, reflecting the accumulation of metabolic carbon dioxide in the deep tropical Pacific. Counterintuitively, downcore application of the Globorotalia menardii calcite fragmentation index (MFI) reveals enhanced glacial sedimentary calcite preservation in the Panama Basin. Together these results point towards a systematic decoupling of bottom water chemistry from biogenic burial fluxes: the crux of the aforementioned traditional paleoproductivity problem.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/232594','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/232594"><span>Interplay between evaporation radiation, and <span class="hlt">ocean</span> mixing in the regulation of <span class="hlt">equatorial</span> Pacific sea surface temperature</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Grossman, R.</p> <p>1995-09-01</p> <p>Sea surface temperature (SST) regulation in the tropical <span class="hlt">oceans</span> is an important aspect of global climate change. It has been observed that SST in the <span class="hlt">equatorial</span> zone has not exceeded 304K over, at least, the past 10,000 years, and probably longer. Furthermore, recent satellite observations from the Earth Radiation Budget Experiment (ERBE) suggest that the greenhouse effect associated with mesoscale organized convection increases with increasing SST at a rate faster than this energy can be re-radiated to space. This suggests that a runaway greenhouse effect is possible in those parts of the tropical <span class="hlt">oceans</span> where mesoscale convective systems (MCS) are prevalent. However, this is not observed. A search for mechanism(s) which can account for SST regulation is underway. Observational and theoretical evidence exists to suggest the importance of other feedback mechanisms as opposed to the cirrus shading and `super greenhouse effect` supported by the thermostat hypothesis. At least some of the time warm SSTs are associated with low wind speeds and low SSTs follow periods of high wind speed. 2 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19453607','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19453607"><span>Latitudinal distribution of prokaryotic picoplankton populations in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schattenhofer, Martha; Fuchs, Bernhard M; Amann, Rudolf; Zubkov, Mikhail V; Tarran, Glen A; Pernthaler, Jakob</p> <p>2009-08-01</p> <p>Members of the prokaryotic picoplankton are the main drivers of the biogeochemical cycles over large areas of the world's <span class="hlt">oceans</span>. In order to ascertain changes in picoplankton composition in the euphotic and twilight zones at an <span class="hlt">ocean</span> basin scale we determined the distribution of 11 marine bacterial and archaeal phyla in three different water layers along a transect across the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> from South Africa (32.9 degrees S) to the UK (46.4 degrees N) during boreal spring. Depth profiles down to 500 m at 65 stations were analysed by catalysed reporter deposition fluorescence in situ hybridization (CARD-FISH) and automated epifluorescence microscopy. There was no obvious overall difference in microbial community composition between the surface water layer and the deep chlorophyll maximum (DCM) layer. There were, however, significant differences between the two photic water layers and the mesopelagic zone. SAR11 (35 +/- 9%) and Prochlorococcus (12 +/- 8%) together dominated the surface waters, whereas SAR11 and Crenarchaeota of the marine group I formed equal proportions of the picoplankton community below the DCM (both approximately 15%). However, due to their small cell sizes Crenarchaeota contributed distinctly less to total microbial biomass than SAR11 in this mesopelagic water layer. Bacteria from the uncultured Chloroflexi-related clade SAR202 occurred preferentially below the DCM (4-6%). Distinct latitudinal distribution patterns were found both in the photic zone and in the mesopelagic waters: in the photic zone, SAR11 was more abundant in the Northern <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> (up to 45%) than in the Southern <span class="hlt">Atlantic</span> gyre (approximately 25%), the biomass of Prochlorococcus peaked in the tropical <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, and Bacteroidetes and Gammaproteobacteria bloomed in the nutrient-rich northern temperate waters and in the Benguela upwelling. In mesopelagic waters, higher proportions of SAR202 were present in both central gyre regions, whereas Crenarchaeota were clearly</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PrOce.134..271C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PrOce.134..271C"><span>Response of the surface tropical <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> to wind forcing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Castellanos, Paola; Pelegrí, Josep L.; Campos, Edmo J. D.; Rosell-Fieschi, Miquel; Gasser, Marc</p> <p>2015-05-01</p> <p>We use 10 years of satellite data (sea level pressure, surface winds and absolute dynamic topography [ADT]) together with Argo-inferred monthly-mean values of near-surface velocity and water transport, to examine how the tropical system of near-surface zonal currents responds to wind forcing. The data is analyzed using complex Hilbert empirical orthogonal functions, confirming that most of the variance has annual periodicity, with maximum amplitudes in the region spanned by the seasonal displacement of the Inter-Tropical Convergence Zone (ITCZ). The ADT mirrors the shape of the upper isopycnals, hence becoming a good indicator of the amount of water stored in the upper <span class="hlt">ocean</span>. Within about 3° from the Equator, where the Coriolis force is small, there is year-long meridional Ekman-transport divergence that would lead to the eastward transport of the <span class="hlt">Equatorial</span> Undercurrent and its northern and southern branches. Beyond 3° of latitude, and at least as far as 20°, the convergence of the Ekman transport generally causes a poleward positive ADT gradient, which sustains the westward South <span class="hlt">Equatorial</span> Current (SEC). The sole exception occurs in summer, between 8°N and 12°N, when an Ekman-transport divergence develops and depletes de amount of surface water, resulting in an ADT ridge-valley system which reverses the ADT gradient and drives the eastward North <span class="hlt">Equatorial</span> Countercurrent (NECC) at latitudes 4-9°N; in late fall, divergence ceases and the NECC drains the ADT ridge, so the ADT gradient again becomes positive and the SEC reappears. The seasonal evolution of a tilted ITCZ controls the surface water fluxes: the wind-induced transports set the surface divergence-convergence, which then drive the ADT and, through the ADT gradients, create the geostrophic jets that close the water balance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017DokES.472...20S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017DokES.472...20S"><span>New data on the composition and age of rocks from the Bathymetrists Seamounts (Eastern margin of the <span class="hlt">equatorial</span> <span class="hlt">Atlantic</span>)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Skolotnev, S. G.; Peyve, A. A.; Bylinskaya, M. E.; Golovina, L. A.</p> <p>2017-01-01</p> <p>The petrology, geochemistry, and isotope ratios of volcanics dredged during the 43rd cruise of R/V Academik Ioffe on the Bathymetrists Seamounts in the eastern <span class="hlt">equatorial</span> <span class="hlt">Atlantic</span> have been studied. These are alkaline volcanics of basic and ultramafic compositions. Spider diagrams of the trace elements of volcanic rocks demonstrate strong fractionation, indicating formation of their primary melts from an enriched mantle source at garnet depth facies. Considering the isotope ratio values of 143Nd/144Nd, 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb, and 87Sr/86Sr and the character of their variations, the volcanic mantle source was chemically heterogeneous: for various volcanic rocks it was a mixture of the mantle components HIMU with EM-1 or EM-2. Limestones dredged together with the volcanics yielded microfossils suggesting a Middle Eocene age of their formation in a carbonate platform environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70013309','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70013309"><span>FERROMANGANESE CRUST RESOURCES IN THE PACIFIC AND <span class="hlt">ATLANTIC</span> <span class="hlt">OCEANS</span>.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Commeau, R.F.; Clark, A.; Johnson, Chad; Manheim, F. T.; Aruscavage, P. J.; Lane, C.M.</p> <p>1984-01-01</p> <p>Ferromanganese crusts on raised areas of the <span class="hlt">ocean</span> 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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>. 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 <span class="hlt">Atlantic</span> <span class="hlt">oceans</span>, with special reference to US EEZ areas. Additional research is needed before more quantitative resource estimates can be made.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-99PP-1033&hterms=atlantic+ocean+mercury&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Datlantic%2Bocean%2Bmercury','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-99PP-1033&hterms=atlantic+ocean+mercury&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Datlantic%2Bocean%2Bmercury"><span>Liberty Bell 7 is retrieved from <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1999-01-01</p> <p>Media and photographers get a close-up view of the Liberty Bell 7 Project Mercury capsule after its recovery from the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> floor where it lay for 38 years. Launched July 21, 1961, the capsule made a successful 16-minute suborbital flight, with astronaut Virgil 'Gus' Grissom aboard, and splashed down in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>. 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 <span class="hlt">ocean</span> floor, until now. Curt Newport, an underwater salvage expert, 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 expedition was sponsored by the Discovery Channel. 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.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-99PP-1032&hterms=atlantic+ocean+mercury&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Datlantic%2Bocean%2Bmercury','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-99PP-1032&hterms=atlantic+ocean+mercury&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Datlantic%2Bocean%2Bmercury"><span>Liberty Bell 7 is retrieved from <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1999-01-01</p> <p>Media and spectators get a close-up view of the Liberty Bell 7 Project Mercury capsule after its recovery from the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> floor where it lay for 38 years. Launched July 21, 1961, the capsule made a successful 16-minute suborbital flight, with astronaut Virgil 'Gus' Grissom aboard, and splashed down in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>. 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 <span class="hlt">ocean</span> floor, until now. Curt Newport, an underwater salvage expert, 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 expedition was sponsored by the Discovery Channel. 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-99PP-1033&hterms=ocean+floor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Docean%2Bfloor','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-99PP-1033&hterms=ocean+floor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Docean%2Bfloor"><span>Liberty Bell 7 is retrieved from <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1999-01-01</p> <p>Media and photographers get a close-up view of the Liberty Bell 7 Project Mercury capsule after its recovery from the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> floor where it lay for 38 years. Launched July 21, 1961, the capsule made a successful 16-minute suborbital flight, with astronaut Virgil 'Gus' Grissom aboard, and splashed down in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>. 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 <span class="hlt">ocean</span> floor, until now. Curt Newport, an underwater salvage expert, 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 expedition was sponsored by the Discovery Channel. 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-99PP-1032&hterms=1032&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3D1032','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-99PP-1032&hterms=1032&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3D1032"><span>Liberty Bell 7 is retrieved from <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1999-01-01</p> <p>Media and spectators get a close-up view of the Liberty Bell 7 Project Mercury capsule after its recovery from the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> floor where it lay for 38 years. Launched July 21, 1961, the capsule made a successful 16-minute suborbital flight, with astronaut Virgil 'Gus' Grissom aboard, and splashed down in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>. 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 <span class="hlt">ocean</span> floor, until now. Curt Newport, an underwater salvage expert, 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 expedition was sponsored by the Discovery Channel. 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMOS53F..08N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMOS53F..08N"><span>Variability of Zonal Currents in the Eastern <span class="hlt">Equatorial</span> Indian <span class="hlt">Ocean</span> on Seasonal to Interannual Time Scales</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nyadjro, E. S.; McPhaden, M. J.</p> <p>2014-12-01</p> <p>We present results on the zonal current variations along the equator in the upper layers of eastern Indian <span class="hlt">Ocean</span> in relation to variations in the Indian <span class="hlt">Ocean</span> Dipole (IOD). Our study utilizes data from the Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction (RAMA) and model outputs from the European Centre for Medium-Range Weather Forecasts - <span class="hlt">Ocean</span> Reanalysis System 4 (ECMWF-ORAS4) for 1960-2011. Surface currents are characterized by strong semi-annual eastward flowing Wyrtki jets in boreal spring and fall, forced by westerly monsoon transition winds along the equator. The fall jet intensifies during negative IOD (NIOD) events when westerlies are stronger than normal but significantly weakens during positive IOD (PIOD) events when westerlies are weaker than normal. Associated with weakened PIOD zonal wind stresses, sea surface height becomes unusually low in the eastern basin and high in the west, setting up an anomalous pressure force that drives increased eastward transport in the thermocline. In contrast, during NIOD events when <span class="hlt">equatorial</span> westerlies and the normal zonal surface height gradient intensify, the eastward zonal current in the thermocline significantly weakens. A surface layer mass budget calculation for the eastern pole of the IOD indicates upwelling at a rate of ~2.9±0.7 Sv during normal periods, increasing by 40-50% during PIOD events and reducing to zero during NIOD events. IOD-related variations in Wyrtki jet and thermocline transports are major influences on these upwelling rates, which are consistent with observed sea surface temperature changes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PalOc..31..522P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PalOc..31..522P"><span>Atmosphere-<span class="hlt">ocean</span> linkages in the eastern <span class="hlt">equatorial</span> Pacific over the early Pleistocene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Povea, Patricia; Cacho, Isabel; Moreno, Ana; Pena, Leopoldo D.; Menéndez, Melisa; Calvo, Eva; Canals, Miquel; Robinson, Rebecca S.; Méndez, Fernando J.; Flores, Jose-Abel</p> <p>2016-05-01</p> <p>Here we present a new set of high-resolution early Pleistocene records from the eastern <span class="hlt">equatorial</span> Pacific (EEP). Sediment composition from <span class="hlt">Ocean</span> Drilling Program Sites 1240 and 1238 is used to reconstruct past changes in the atmosphere-<span class="hlt">ocean</span> system. Particularly remarkable is the presence of laminated diatom oozes (LDOs) during glacial periods between 1.85 and 2.25 Ma coinciding with high fluxes of opal and total organic carbon. Relatively low lithic particles (coarse and poorly sorted) and iron fluxes during these glacial periods indicate that the increased diatom productivity did not result from dust-stimulated fertilization events. We argue that glacial fertilization occurred through the advection of nutrient-rich waters from the Southern <span class="hlt">Ocean</span>. In contrast, glacial periods after 1.85 Ma are characterized by enhanced dust transport of finer lithic particles acting as a new source of nutrients in the EEP. The benthic ecosystem shows dissimilar responses to the high productivity recorded during glacial periods before and after 1.85 Ma, which suggests that the transport processes delivering organic matter to the deep sea also changed. Different depositional processes are interpreted to be the result of two distinct glacial positions of the Intertropical Convergence Zone (ITCZ). Before 1.85 Ma, the ITCZ was above the equator, with weak local winds and enhanced wet deposition of dust. After 1.85 Ma, the glacial ITCZ was displaced northward, thus bringing stronger winds and stimulating upwelling in the EEP. The glacial period at 1.65 Ma with the most intense LDOs supports a rapid southward migration of the ITCZ comparable to those glacial periods before 1.85 Ma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMPP41C1784K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMPP41C1784K"><span>Black carbon in deep-sea sediments from the northeastern <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, D.; Lee, Y.; Hyeong, K.; Yoo, C.</p> <p>2011-12-01</p> <p>Deep-sea sediment core is a good archive for understanding the land-<span class="hlt">ocean</span> interactions via atmosphere, due to it is little influenced by fluvial and continental shelf processes. This study dealt with black carbon(BC) in a 328 cm-long piston core collected from the northeastern <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span> (16°12'N, 125°59'W), covering the last 15 Ma (Hyeong at al., 2004). BC is a common name of carbon continuum formed by incomplete combustion of fossil fuels and plant materials. Though it may react with ozone and produce water-soluble organic carbon, BC has commonly refractory nature. Thus BC in preindustrial sediment can be a tracer of forest-fire events. BC is purely terrestrial in origin, and is transported to marine environments by atmospheric and fluvial processes. Therefore, distribution of BC in deep-sea sediments could be used to understand atmospheric circulation. Chemical oxidation was used to determine BC in this study following Lim and Cachier (1996). Concentration of BC varies from 0.010% to 0.233% of total sediments. Mass accumulation rate (MAR) of BC ranged between 0.077 mg/cm^2/1000 yrs and 47.49 mg/cm^21000 yrs. It is noted that MAR in sediments younger than 8 Ma (av. 9.0 mg/cm^2/1000 yrs) is higher than that in sediments older than 8 Ma (av. 3.2 mg/cm^2/1000 yrs). Stable carbon isotope value of BC increases with time from the low δ13C value near 13 Ma until it reaches the highest value near 4 Ma. Change of MAR seems to be related to the meridional migration of Intertropical Convergence Zone (ITCZ) at around 8 Ma in the study area (cf., Hyeong at al., 2004). Accordingly, higher BC content in sediment younger than 8 Ma seems to be accounted for by its derivation from the Northern Hemisphere compared to that from the Southern Hemisphere in older sediment. Increase of carbon isotope value with time seems to be related to expansion of C4 grassland. C4 grassland expansion might have been caused by change of atmosphreic cycle, which moved dry subtropical</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.G31A0911V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.G31A0911V"><span>Sea Level Variation at the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> from Altimetry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vigo, I.; Sanchez-Reales, J. M.; Belda, S.</p> <p>2012-12-01</p> <p>About twenty years of multi-satellite radar altimeter data are analyzed to investigate the sea-level variation (SLV) of the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>. In particular seasonal variations and inter-seasonal trends are studied. Sea surface temperature and ice mass lost variations at Greenland are investigated as potential contributors of SLV in the case. It was found a quadratic acceleration term to be significant at some areas mainly located at the sub-polar gyre region. Results are consistent with changes in temperature data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11557890','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11557890"><span>Glacial surface temperatures of the southeast <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sachs, J P; Anderson, R F; Lehman, S J</p> <p>2001-09-14</p> <p>A detailed record of sea surface temperature from sediments of the Cape Basin in the subtropical South <span class="hlt">Atlantic</span> indicates a previously undocumented progression of marine climate change between 41 and 18 thousand years before the present (ky B.P.), during the last glacial period. Whereas marine records typically indicate a long-term cooling into the Last Glacial Maximum (around 21 ky B.P.) consistent with gradually increasing global ice volume, the Cape Basin record documents an interval of substantial temperate <span class="hlt">ocean</span> warming from 41 to 25 ky B.P. The pattern is similar to that expected in response to changes in insolation owing to variations in Earth's tilt.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AtmEn.133..165L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AtmEn.133..165L"><span>Aerosol isotopic ammonium signatures over the remote <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lin, C. T.; Jickells, T. D.; Baker, A. R.; Marca, A.; Johnson, M. T.</p> <p>2016-05-01</p> <p>We report aerosol ammonium 15N signatures for samples collected from research cruises on the South <span class="hlt">Atlantic</span> and Caribbean using a new high sensitivity method. We confirm a pattern of isotopic signals from generally light (δ15N -5 to -10‰), for aerosols with very low (<2 nmol m-3) ammonium concentrations from the remote high latitude <span class="hlt">ocean</span>, to generally heavier values (δ15N +5 to +10‰), for aerosols collected in temperate and tropical latitudes and with higher ammonium concentrations (>2 nmol m-3). We discuss whether this reflects a mixing of aerosols from two end-members (polluted continental and remote marine emissions), or isotopic fractionation during aerosol transport.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15994552','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15994552"><span><span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> forcing of North American and European summer climate.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sutton, Rowan T; Hodson, Daniel L R</p> <p>2005-07-01</p> <p>Recent extreme events such as the devastating 2003 European summer heat wave raise important questions about the possible causes of any underlying trends, or low-frequency variations, in regional climates. Here, we present new evidence that basin-scale changes in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, probably related to the thermohaline circulation, have been an important driver of multidecadal variations in the summertime climate of both North America and western Europe. Our findings advance understanding of past climate changes and also have implications for decadal climate predictions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24277830','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24277830"><span>Atmospheric deposition of methanol over the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yang, Mingxi; Nightingale, Philip D; Beale, Rachael; Liss, Peter S; Blomquist, Byron; Fairall, Christopher</p> <p>2013-12-10</p> <p>In the troposphere, methanol (CH3OH) is present ubiquitously and second in abundance among organic gases after methane. In the surface <span class="hlt">ocean</span>, 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 <span class="hlt">Atlantic</span>. The flux of methanol was consistently from the atmosphere to the <span class="hlt">ocean</span>. 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 <span class="hlt">oceanic</span> uptake of methanol and examine the lifetimes of this compound in the lower atmosphere and upper <span class="hlt">ocean</span> with respect to gas exchange. We also constrain the molecular diffusional resistance above the <span class="hlt">ocean</span> surface-an important term for improving air-sea gas exchange models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850017722&hterms=many+oceans+world&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmany%2Boceans%2Bworld','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850017722&hterms=many+oceans+world&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmany%2Boceans%2Bworld"><span>North <span class="hlt">Atlantic</span> Deep Water and the World <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gordon, A. L.</p> <p>1984-01-01</p> <p>North <span class="hlt">Atlantic</span> Deep Water (NADW) by being warmer and more saline than the average abyssal water parcel introduces heat and salt into the abyssal <span class="hlt">ocean</span>. The source of these properties is upper layer or thermocline water considered to occupy the <span class="hlt">ocean</span> less dense than sigma-theta of 27.6. That NADW convects even though it's warmer than the abyssal <span class="hlt">ocean</span> is obviously due to the high salinity. In this way, NADW formation may be viewed as saline convection. The counter force removing heat and salinity (or introducing fresh water) is usually considered to to take place in the Southern <span class="hlt">Ocean</span> where upwelling deep water is converted to cold fresher Antarctic water masses. The Southern <span class="hlt">ocean</span> convective process is driven by low temperatures and hence may be considered as thermal convection. A significant fresh water source may also occur in the North Pacific where the northward flowing of abyssal water from the 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3864313','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3864313"><span>Atmospheric deposition of methanol over the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Yang, Mingxi; Nightingale, Philip D.; Beale, Rachael; Liss, Peter S.; Blomquist, Byron; Fairall, Christopher</p> <p>2013-01-01</p> <p>In the troposphere, methanol (CH3OH) is present ubiquitously and second in abundance among organic gases after methane. In the surface <span class="hlt">ocean</span>, 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 <span class="hlt">Atlantic</span>. The flux of methanol was consistently from the atmosphere to the <span class="hlt">ocean</span>. 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 <span class="hlt">oceanic</span> uptake of methanol and examine the lifetimes of this compound in the lower atmosphere and upper <span class="hlt">ocean</span> with respect to gas exchange. We also constrain the molecular diffusional resistance above the <span class="hlt">ocean</span> surface—an important term for improving air–sea gas exchange models. PMID:24277830</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PApGe.174..477Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PApGe.174..477Y"><span>North <span class="hlt">Equatorial</span> Indian <span class="hlt">Ocean</span> Convection and Indian Summer Monsoon June Progression: a Case Study of 2013 and 2014</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yadav, Ramesh Kumar; Singh, Bhupendra Bahadur</p> <p>2017-02-01</p> <p>The consecutive summer monsoons of 2013 and 2014 over the Indian subcontinent saw very contrasting onsets and progressions during the initial month. While the 2013 monsoon saw the timely onset and one of the fastest progressions during the recent decades, 2014 had a delayed onset and a slower progression phase. The monthly rainfall of June 2013 was +34 %, whereas in 2014 it was -43 % of its long-period average. The progress/onset of monsoon in June is influenced by large-scale circulation and local feedback processes. But, in 2013 (2014), one of the main reasons for the timely onset and fastest progression (delayed onset and slower progression) was the persistent strong (weak) convection over the north <span class="hlt">equatorial</span> Indian <span class="hlt">Ocean</span> during May. This resulted in a strong (weak) Hadley circulation with strong (weak) ascent and descent over the north <span class="hlt">equatorial</span> Indian <span class="hlt">Ocean</span> and the South Indian <span class="hlt">Ocean</span>, respectively. The strong (weak) descent over the south Indian <span class="hlt">Ocean</span> intensified (weakened) the Mascarene High, which in turn strengthened (weakened) the cross-<span class="hlt">equatorial</span> flow and hence the monsoonal circulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMPP43A2291P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMPP43A2291P"><span>Global Sea surface stability and significant paleoceanographic episodes between the western <span class="hlt">Equatorial</span> Pacific, Bahama Bank of Caribbean, and western Pacific <span class="hlt">Ocean</span> during the Neogene based on calcareous nannofossil productivity and size variations in correlation to the global climatic events</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pratiwi, S. D.; Sato, T.</p> <p>2016-12-01</p> <p>We investigated the calcareous nannofossils assemblages to reconstruct the Neogene paleoceanography of Bahama Bank of <span class="hlt">Atlantic</span>, <span class="hlt">Equatorial</span> Pacific and western Pacific <span class="hlt">Ocean</span> from the ODP Sites 1007, 805, and 782 and correlate with the global events. The absolute abundant of coccolith (number/g) are gradually increased from NN2 throughout NN19 Zone, while the relative abundance of Discoaster is decreased at Sites 782 and 805 in the western Pacific and western <span class="hlt">Equatorial</span> Pacific <span class="hlt">Ocean</span>. The maximum size of Reticulofenestra increased until 8.8 Ma which shows the oligotrophic conditions with sea surface stratification and thermocline (Fig.). The changes of the modal and maximum size of Reticulofenestra which are strongly reflected the collapse of sea surface stability, show four times in 8.8 Ma, 6.4 Ma, 5.4 Ma and 3.75 Ma at Site 782, and in 15.4 Ma, 8.8 Ma, 5.4 Ma and 3.75 Ma at Site 805. On the basis of relationship between the changes of maximum sizes of Reticulofenestra and nutrient condition, these eutrophication events are clearly traceable to the western Pacific, Bahama Bank, and to the <span class="hlt">Equatorial</span> Pacific <span class="hlt">Ocean</span>. Two paleoceanographic events found in 8.8 Ma and 3.75 Ma are interpreted as change to high nutrient condition resulted in the intensify of Asian Monsoon and closure of Panama Isthmus.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMOS32A..03H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMOS32A..03H"><span>Long Range Kelvin Wave Propagation of Transport Variations in the Pacific <span class="hlt">Ocean</span> <span class="hlt">Equatorial</span> Currents: Part II</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Halpern, D.; Fukumori, I.; Menemenlis, D.; Wang, X.</p> <p>2013-12-01</p> <p>In Part I, Knox and Halpern (Journal of Marine Research, 40 Supplement, 329-339, 1982) vertically integrated zonal current observations recorded in March-May 1980 at seven depths from the thermocline to 15 m at the equator and 75 km north and south of the equator near 152°W and also simultaneously at three similar sites at 110°W. Their in-situ current measurements provided the first persuasive evidence of Kelvin wave motion propagating within the <span class="hlt">Equatorial</span> Undercurrent (EUC). A 7-day decrease in transport at peak amplitude of the Kelvin wave pulse at 152°W and 110°W has remained a curiosity with regards to its repeatability at other times within the year and in other years. The advent of realistic currents generated with an <span class="hlt">ocean</span> general circulation model constrained by observations (excluding current measurements) provided an opportunity to re-explore Kelvin wave motion in the Pacific EUC. We use the Estimating the Circulation and Climate of the <span class="hlt">Ocean</span> (ECCO) - Ice interactions in Earth System (IcES) solutions or <span class="hlt">ocean</span> state estimates, which represent complete, consistent, and optimal statistical estimates of the global <span class="hlt">ocean</span> state. ECCO-IcES solutions exist for 2004 and four other years. Twelve 10-m thick layers cover the top 120 m with nine additional layers in the uppermost 400 m. The horizontal grid spacing is 19 km and 3-day averaged quantities are archived. Three longitudes (170°W, 140°W, 110°W) were initially chosen to examine Kelvin wave characteristics; additional longitudes will be described. The large burst in ECCO-IcES EUC transport (defined as eastward flow between the surface and 400 m and from 1.5°S to 1.5°N) in April-May 2004 replicated the well-known annual surfacing of the EUC. The large bursts of EUC transport at 140°W in late January, late April, middle July, and early September and a more modest burst in early November compared exceedingly well with similar bursts at 170°W and 110°W. The average magnitude at 140°W was 50 Sv. Each</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA567452','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA567452"><span><span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> Circulation at the Last Glacial Maximum: Inferences from Data and Models</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2012-09-01</p> <p>development of estimates of <span class="hlt">ocean</span> state that are (1) within error bounds of a given dataset, (2) consistent with known <span class="hlt">oceanic</span> dynamics, and (3...United States Government. This thesis should be cited as: Holly Janine Dail, 2012. <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> Circulation at the Last Glacial Maximum: Inferences...this thesis a novel approach to dynamical reconstruction is applied to make estimates of LGM <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> state that are consistent with these proxy</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMPP41A1489S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMPP41A1489S"><span>Productivity response to the PETM in the North <span class="hlt">Atlantic</span> and South Indian <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sime, T.; Kanamaru-Shinn, K.; Stoll, H. M.; Shimizu, N.</p> <p>2009-12-01</p> <p>During the Paleocene Eocene Thermal Maximum (PETM), transient changes in climate and the <span class="hlt">ocean</span> carbonate system resulted from a major release of isotopically light C into the <span class="hlt">ocean</span> and atmosphere. We examine the productivity response of calcareous planktonic nannofossils to the dramatic climate and ecosystem changes at DSDP Site 401 in the Bay of Biscay, North <span class="hlt">Atlantic</span>, and ODP Site 738, Southernmost Indian <span class="hlt">Ocean</span>. We use the productivity indicator based on Sr/Ca ratios of coccoliths, which is independent of changes in sediment accumulation rate. Sr/Ca is measured in individually picked coccoliths using secondary ion mass spectrometry. At site 401, Sr/Ca ratios in coccoliths of Toweius and Coccolithus pelagicus increase during the PETM, indicating an increase in coccolithophore productivity until the PETM isotope recovery. We are working to characterize the background pre-PETM variability at this site to establish if this increase is a unique response to PETM environmental changes. Bulk sediment Sr/Ca ratios from the same depths, measured by ICP-AES, do not covary with Sr/Ca Coccolithus or Toweius but instead increases monotonically towards shallower depths. One possible explanation is a change in proportion of Sr-poor type coccoliths, such as Discoaster sp. and Zygrhab sp. Stable oxygen and carbon isotopes at site 401 exhibit extremely similar values among three different coccolith size fractions dominated by different genera, consistent with limited vital effects as observed at other sites. At ODP 738, Sr/Ca ratios in Toweius increase during the later part of the PETM and decrease by the end of the recovery, indicating a brief productivity increase. This increase is clearly beyond the background variability before the PETM or during the first part of the CIE. We are assessing whether a similar pattern is observed in Coccolithus. We will also similarly characterize productivity response to ELMO in the <span class="hlt">Equatorial</span> Pacific and Southernmost Indian <span class="hlt">Ocean</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050176045','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050176045"><span><span class="hlt">Oceanic</span> Situational Awareness Over the Western <span class="hlt">Atlantic</span> Track Routing System</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Welch, Bryan; Greenfeld, Israel</p> <p>2005-01-01</p> <p>Air traffic control (ATC) mandated, aircraft separations over the <span class="hlt">oceans</span> impose a limitation on traffic capacity for a given corridor, given the projected traffic growth over the Western <span class="hlt">Atlantic</span> Track Routing System (WATRS). The separations result from a lack of acceptable situational awareness over <span class="hlt">oceans</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JSAES..77..276P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JSAES..77..276P"><span>The potential of the coral species Porites astreoides as a paleoclimate archive for the Tropical South <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pereira, N. S.; Sial, A. N.; Frei, R.; Ullmann, C. V.; Korte, C.; Kikuchi, R. K. P.; Ferreira, V. P.; Kilbourne, K. H.</p> <p>2017-08-01</p> <p>The aragonitic skeletons of corals are unique archives of geochemical tracers that can be used as proxies for environmental conditions with high fidelity and sub-annual resolution. Such records have been extensively used for reconstruction of climatic conditions in the Pacific and Indian <span class="hlt">Oceans</span>, Red Sea and Caribbean, but lack for the <span class="hlt">Equatorial</span> South <span class="hlt">Atlantic</span>. Here we present coral-based records of Sr/Ca, δ18O and δ13C and the first δ18O-SST calibration for the scleractinian coral species Porites astreoides from the Rocas Atoll, <span class="hlt">Equatorial</span> South <span class="hlt">Atlantic</span>. The investigated geochemical proxies for P. astreoides presented a very well-developed seasonal cyclicity in all proxies. We use the monthly means of δ18O and SST from the period of 2001-2013 to propose a calibration for a paleothermometer based on Porites, which gives T(°C) = -8.69(±0.79)* δ18O -7.05(±3.14), and yielded a SST δ18O-depended reconstruction with fidelity better than 0.5 °C for most of the record. Biases of up to 2 °C might be associated with reduced growth rate periods of the coral record. The Sr/Ca data show systematic, annual fluctuations but analyses are too imprecise to propose a Sr/Ca-SST calibration. The δ13C values are found to vary in phase with δ18O and Sr/Ca and are interpreted to be controlled by solar irradiation-modulated photosynthetic activity on the annual level. Our findings extend the global data base of coral records, contributing to further investigations using coral skeleton as environmental archives. In particular, the present study helps to better understand the climate variability of the South <span class="hlt">Atlantic</span> tropical <span class="hlt">ocean</span>-atmosphere system.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.177....1L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.177....1L"><span>Neodymium isotopic composition and concentration in the western North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>: Results from the GEOTRACES GA02 section</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lambelet, Myriam; van de Flierdt, Tina; Crocket, Kirsty; Rehkämper, Mark; Kreissig, Katharina; Coles, Barry; Rijkenberg, Micha J. A.; Gerringa, Loes J. A.; de Baar, Hein J. W.; Steinfeldt, Reiner</p> <p>2016-03-01</p> <p>The neodymium (Nd) isotopic composition of seawater is commonly used as a proxy to study past changes in the thermohaline circulation. The modern database for such reconstructions is however poor and the understanding of the underlying processes is incomplete. Here we present new observational data for Nd isotopes and concentrations from twelve seawater depth profiles, which follow the flow path of North <span class="hlt">Atlantic</span> Deep Water (NADW) from its formation region in the North <span class="hlt">Atlantic</span> to the northern <span class="hlt">equatorial</span> <span class="hlt">Atlantic</span>. Samples were collected during two cruises constituting the northern part of the Dutch GEOTRACES transect GA02 in 2010. The results show that the different water masses in the subpolar North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, which ultimately constitute NADW, have the following Nd isotope characteristics: Upper Labrador Sea Water (ULSW), εNd = -14.2 ± 0.3; Labrador Sea Water (LSW), εNd = -13.7 ± 0.9; Northeast <span class="hlt">Atlantic</span> Deep Water (NEADW), εNd = -12.5 ± 0.6; Northwest <span class="hlt">Atlantic</span> Bottom Water (NWABW), εNd = -11.8 ± 1.4. In the subtropics, where these source water masses have mixed to form NADW, which is exported to the global <span class="hlt">ocean</span>, upper-NADW is characterised by εNd values of -13.2 ± 1.0 (2sd) and lower-NADW exhibits values of εNd = -12.4 ± 0.4 (2sd). While both signatures overlap within error, the signature for lower-NADW is significantly more radiogenic than the traditionally used value for NADW (εNd = -13.5) due to the dominance of source waters from the Nordic Seas (NWABW and NEADW). Comparison between the concentration profiles and the corresponding Nd isotope profiles with other water mass properties such as salinity, silicate concentrations, neutral densities and chlorofluorocarbon (CFC) concentration provides novel insights into the geochemical cycle of Nd and reveals that different processes are necessary to account for the observed Nd characteristics in the subpolar and subtropical gyres and throughout the vertical water column. While our data set</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1710720W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1710720W"><span>Pathways of <span class="hlt">Atlantic</span> Waters into the Arctic <span class="hlt">Ocean</span>: Eddy-permitting <span class="hlt">ocean</span> and sea ice simulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wekerle, Claudia; von Appen, Wilken-Jon; Danilov, Sergey; Jung, Thomas; Kanzow, Torsten; Schauer, Ursula; Timmermann, Ralph; Wang, Qiang</p> <p>2015-04-01</p> <p>Fram Strait is the only deep gateway connecting the central Arctic with the North <span class="hlt">Atlantic</span>. Boundary currents on each side are responsible for the exchange of water masses between the Arctic and North <span class="hlt">Atlantic</span>. The East Greenland Current (EGC) carries fresh and cold Arctic waters and sea ice southward, whereas the West Spitsbergen Current (WSC) carries warm <span class="hlt">Atlantic</span> Waters (AW) into the Arctic <span class="hlt">Ocean</span>. The complex topography in Fram Strait leads to a branching of the northward flowing WSC, with one branch recirculating between 78°N and 81°N which then joins the EGC. To date, the dynamics as well as the precise location of this recirculation are unclear. The goal of this research project is to quantify the amount and variability of AW which recirculates immediately in Fram Strait, and to investigate the role of atmospheric forcing and <span class="hlt">oceanic</span> meso-scale eddies for the recirculation. We use simulations carried out with a global configuration of the Finite Element Sea ice-<span class="hlt">Ocean</span> Model (FESOM) at eddy-permitting scales. The advantage of this model is the finite element discretization of the governing equations, which allows us to locally refine the mesh in areas of interest and keep it coarse in other parts of the global <span class="hlt">oceans</span> without the need for traditional nesting. Here we will show the first results of the model validation. The model has ~9 km resolution in the Nordic Seas and Fram Strait and 1 deg south of 50°N. We assess the model capabilities in simulating the <span class="hlt">ocean</span> circulation in the Nordic Seas and Fram Strait by comparing with the available observational data, e.g. with data from the Fram Strait oceanographic mooring array. The <span class="hlt">ocean</span> volume and heat transport from the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> into the Nordic Seas and at the Fram Strait are analyzed. Our results show that the model can capture some of the observed key <span class="hlt">ocean</span> properties in our region of interest, while some tuning is required to further improve the model. In the next phase of this project we will focus</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007JGRC..112.6004E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007JGRC..112.6004E"><span>Eddy length scales in the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Eden, Carsten</p> <p>2007-06-01</p> <p>Eddy length scales are calculated from satellite altimeter products and in an eddy-resolving model of the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>. Four different measures for eddy length scales are derived from kinetic energy densities in wave number space and spatial decorrelation scales. Observational estimates and model simulation agree well in all these measures near the surface. As found in previous studies, all length scales are, in general, decreasing with latitude. They are isotropic and proportional to the local first baroclinic Rossby radius (Lr) north of about 30°N, while south of 30°N (or for Lr > 30 km), zonal length scales tend to be larger than meridional ones, and (scalar) length scales show no clear relation to Lr anymore. Instead, they appear to be related to the local Rhines scale. In agreement with a recent theoretical prediction by Theiss [2004], the observed and simulated pattern of eddy length scales appears to be indicative of two different dynamical regimes in the North <span class="hlt">Atlantic</span>: anisotropic turbulence in the subtropics and isotropic turbulence in the subpolar North <span class="hlt">Atlantic</span>. Both regions can be roughly characterized by the ration between Lr and the Rhines scales (LR), with LR > Lr in the isotropic region and LR < Lr in the anisotropic region. The critical latitude that separates both regions, i.e., where LR = Lr, is about 30°N.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011E%26PSL.306....1R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011E%26PSL.306....1R"><span>Iron isotopes in the seawater of the <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span>: New constraints for the <span class="hlt">oceanic</span> iron cycle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Radic, Amandine; Lacan, Francois; Murray, James W.</p> <p>2011-06-01</p> <p>This study presents the isotopic compositions and concentrations of dissolved and particulate iron from two seawater profiles of the western and central <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span>, sampled during the EUCFe cruise. Most of the δ 56Fe values are positive (relative to IRMM-14), from + 0.01 to + 0.58‰ in the dissolved fraction (DFe) and from - 0.02 to + 0.46‰ in the particulate fraction (PFe). The mean measurement uncertainty of ± 0.08‰ (2SD) allows the observation of significant variations. Most of the isotope variations occur in the vertical and not in the horizontal direction, implying that each isotope signature is preserved over long distances within a water mass. The thermocline waters of the Papua New Guinea (PNG) area, mostly influenced by sedimentary inputs, display a mean δ 56DFe value of + 0.37‰ (± 0.15‰, 2SD). This isotopic signature suggests that the process releasing dissolved iron into the seawater in this area is a non reductive dissolution of sediments (discharged by local rivers and likely re-suspended by strong boundary currents), rather than Dissimilatory Iron Reduction (DIR) within the sediment (characterized by negative δ 56DFe). These positive δ 56DFe values seem to be the result of a mean isotopic fractionation of Δ 56Fe DFe-PFe = + 0.20‰ (± 0.11‰, 2SD) produced by the non reductive dissolution. At 0°N, 180°E, the Fe isotope signature of the <span class="hlt">Equatorial</span> Undercurrent (EUC) waters is identical to that of the PNG station within the range of the uncertainty. This suggests that the dissolved iron feeding the EUC, and ultimately the eastern Pacific high nutrient low chlorophyll area, is of PNG origin, likely released by a non reductive dissolution of terrigenous sediments. Significant Fe removals are observed within the thermocline and the intermediate waters between the PNG and the open <span class="hlt">ocean</span> stations. The corresponding isotopic fractionations appear to be small, with Δ 56Fe removed-SW Fe values of -0.30 ± 0.31‰ to -0.18 ± 0</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18258344','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18258344"><span>Estimates of upwelling rates in the Arabian Sea and the <span class="hlt">equatorial</span> Indian <span class="hlt">Ocean</span> based on bomb radiocarbon.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bhushan, R; Dutta, K; Somayajulu, B L K</p> <p>2008-10-01</p> <p>Radiocarbon measurements were made in the water column of the Arabian Sea and the <span class="hlt">equatorial</span> Indian <span class="hlt">Ocean</span> during 1994, 1995 and 1997 to assess the temporal variations in bomb 14C distribution and its inventory in the region with respect to GEOSECS measurements made during 1977-1978. Four GEOSECS stations were reoccupied (three in the Arabian Sea and one in the <span class="hlt">equatorial</span> Indian <span class="hlt">Ocean</span>) during this study, with all of them showing increased penetration of bomb 14C along with decrease in its surface water activity. The upwelling rates derived by model simulation of bomb 14C depth profile using the calculated exchange rates ranged from 3 to 9 m a(-1). The western region of the Arabian Sea experiencing high wind-induced upwelling has higher estimated upwelling rates. However, lower upwelling rates obtained for the stations occupied during this study could be due to reduced 14C gradient compared to that during GEOSECS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011aogs...22..101L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011aogs...22..101L"><span>Near-<span class="hlt">Equatorial</span> Convective Regimes Over the Indian <span class="hlt">Ocean</span> as Revealed by Synergistic Analysis of Satellite Observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Levy, Gad; Geiss, Andrew; Ramesh Kumar, M. R.</p> <p></p> <p>We examine the organization and temporal evolution of deep convection in relation to the low level flow over the Indian <span class="hlt">Ocean</span> by a synergistic analysis of several satellite datasets for wind, rainfall, Outgoing Longwave Radiation (OLR) and cloud liquid water. We show that during the active Indian monsoon season, symmetric instability is present and is directly linked to organized convection and the off-<span class="hlt">equatorial</span> location of the InterTropical Convergence Zone (ITCZ). The inertial regime interacts with and is controlled by monsoon and cross-<span class="hlt">equatorial</span> flow. We characterize the dominant regimes of deep convective organization and the possible <span class="hlt">ocean</span>-atmosphere mechanisms that control them at different phases of the Indian Monsoon. Ongoing work on development of algorithms for automated identification of convective regimes in climate data and their application and testing on 30 years of OLR data are discussed, and preliminary results of the double ITCZ organization in climate data are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.T13A1124C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.T13A1124C"><span>Extensional and Transtensional Tectonics of the Manihiki Plateau, Western <span class="hlt">Equatorial</span> Pacific <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Coffin, M. F.; Werner, R.; Hauff, F.; Hoernle, K.; Scientific Party, F.</p> <p>2007-12-01</p> <p>Standing several kilometers above surrounding seafloor, the submarine Manihiki Plateau, an <span class="hlt">oceanic</span> large igneous province (LIP), encompasses ~800,000 km2 of seafloor in the western <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span>. Of Early Cretaceous (~120 Ma) age, the plateau comprises three major structural highs. The High Plateau to the east contains several islands, including the eponymous Manihiki atoll. To the west, the Western Plateaus lie approximately one kilometer deeper; they are bifurcated by elongated, overall northeast-trending, bathymetric lows known as the Danger Islands troughs (DITs). North of the Western Plateaus is the small, nearly separate North Plateau that is separated from the High Plateau (and contiguous NE portion of the Western Plateaus) by the High-North Basin. In May-June 2007, we acquired extensive multibeam bathymetry and reflectivity over all three structural highs and their flanks during the 40-day F.S. Sonne cruise 193. On the basis of these new as well as pre-existing data, we propose a tectonic model for post-emplacement, probable Late Cretaceous deformation of the Manihiki Plateau involving both extensional and transtensional deformation. In our model, the High-North Basin probably formed by seafloor spreading; the northwestern margin of the contiguous NE portion of the Western Plateaus-High Plateau and the southeastern margin of the North Plateau are conjugate rifted margins, whose separation approximately equals the right-lateral offset between the southern flanks of Western Plateaus on either side of the DITs. The curvilinear southwest boundary of the High-North Basin consists of several pull-apart basins that abut the steep northeast flank of the Western plateaus; LIP and normal <span class="hlt">oceanic</span> crust are juxtaposed along this boundary. The right-lateral relict plate boundary continues uninterrupted to the south of the deep <span class="hlt">ocean</span> basin as the DITs, which in the study area comprise a series of major en echelon, right- lateral faults that step to the right</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2012-10-17/pdf/2012-25646.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2012-10-17/pdf/2012-25646.pdf"><span>77 FR 63722 - Special Local Regulations; Palm Beach World Championship, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>; Jupiter, FL</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2012-10-17</p> <p>..., <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>; Jupiter, FL AGENCY: Coast Guard, DHS. ACTION: Temporary final rule. SUMMARY: The Coast... Indiantown Road and Donald Ross Road, just offshore of Jupiter, Florida during the Palm Beach World... will be held on the waters of the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, just offshore of Jupiter, Florida. The high speed...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2012-08-20/pdf/2012-20336.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2012-08-20/pdf/2012-20336.pdf"><span>77 FR 50019 - Safety Zone; Cocoa Beach Air Show, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Cocoa Beach, FL</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2012-08-20</p> <p>... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Cocoa Beach Air Show, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Cocoa... establishing a temporary safety zone on the waters of the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> located east of Cocoa Beach, Florida during the Cocoa Beach Air Show. The Cocoa Beach Air Show will include aircraft engaging in aerobatic...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title33-vol3/pdf/CFR-2014-title33-vol3-sec334-580.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title33-vol3/pdf/CFR-2014-title33-vol3-sec334-580.pdf"><span>33 CFR 334.580 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> near Port Everglades, Fla.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> 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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title33-vol3/pdf/CFR-2012-title33-vol3-sec334-580.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title33-vol3/pdf/CFR-2012-title33-vol3-sec334-580.pdf"><span>33 CFR 334.580 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> near Port Everglades, Fla.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> 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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title33-vol2/pdf/CFR-2013-title33-vol2-sec165-714.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title33-vol2/pdf/CFR-2013-title33-vol2-sec165-714.pdf"><span>33 CFR 165.714 - Regulated Navigation Area; <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Charleston, SC.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Regulated Navigation Area; <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Charleston, SC. 165.714 Section 165.714 Navigation and Navigable Waters COAST GUARD... § 165.714 Regulated Navigation Area; <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Charleston, SC. (a) Location. The following area is...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title33-vol3/pdf/CFR-2013-title33-vol3-sec334-130.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title33-vol3/pdf/CFR-2013-title33-vol3-sec334-130.pdf"><span>33 CFR 334.130 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Wallops Island and Chincoteague Inlet, Va.; danger zone.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Wallops Island and Chincoteague Inlet, Va.; danger zone. 334.130 Section 334.130 Navigation and Navigable Waters... REGULATIONS § 334.130 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Wallops Island and Chincoteague Inlet, Va.; danger zone. (a) The area...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title33-vol3/pdf/CFR-2014-title33-vol3-sec334-390.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title33-vol3/pdf/CFR-2014-title33-vol3-sec334-390.pdf"><span>33 CFR 334.390 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> south of entrance to Chesapeake Bay; firing range.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> south of entrance to Chesapeake Bay; firing range. 334.390 Section 334.390 Navigation and Navigable Waters CORPS OF....390 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> south of entrance to Chesapeake Bay; firing range. (a) The danger zone. A section...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title33-vol3/pdf/CFR-2012-title33-vol3-sec334-390.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title33-vol3/pdf/CFR-2012-title33-vol3-sec334-390.pdf"><span>33 CFR 334.390 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> south of entrance to Chesapeake Bay; firing range.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> south of entrance to Chesapeake Bay; firing range. 334.390 Section 334.390 Navigation and Navigable Waters CORPS OF....390 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> south of entrance to Chesapeake Bay; firing range. (a) The danger zone. A section...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title33-vol1/pdf/CFR-2010-title33-vol1-sec110-182.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title33-vol1/pdf/CFR-2010-title33-vol1-sec110-182.pdf"><span>33 CFR 110.182 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Fort George Inlet, near Mayport, Fla.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> 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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title33-vol2/pdf/CFR-2010-title33-vol2-sec165-714.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title33-vol2/pdf/CFR-2010-title33-vol2-sec165-714.pdf"><span>33 CFR 165.714 - Regulated Navigation Area; <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Charleston, SC.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Regulated Navigation Area; <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Charleston, SC. 165.714 Section 165.714 Navigation and Navigable Waters COAST GUARD... § 165.714 Regulated Navigation Area; <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Charleston, SC. (a) Location. The following area is...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title33-vol3/pdf/CFR-2012-title33-vol3-sec334-130.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title33-vol3/pdf/CFR-2012-title33-vol3-sec334-130.pdf"><span>33 CFR 334.130 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Wallops Island and Chincoteague Inlet, Va.; danger zone.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Wallops Island and Chincoteague Inlet, Va.; danger zone. 334.130 Section 334.130 Navigation and Navigable Waters... REGULATIONS § 334.130 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Wallops Island and Chincoteague Inlet, Va.; danger zone. (a) The area...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title33-vol3/pdf/CFR-2013-title33-vol3-sec334-580.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title33-vol3/pdf/CFR-2013-title33-vol3-sec334-580.pdf"><span>33 CFR 334.580 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> near Port Everglades, Fla.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> 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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title33-vol1/pdf/CFR-2011-title33-vol1-sec110-182.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title33-vol1/pdf/CFR-2011-title33-vol1-sec110-182.pdf"><span>33 CFR 110.182 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Fort George Inlet, near Mayport, Fla.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> 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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title33-vol2/pdf/CFR-2010-title33-vol2-sec165-T01-0542.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title33-vol2/pdf/CFR-2010-title33-vol2-sec165-T01-0542.pdf"><span>33 CFR 165.T01-0542 - Safety Zones: Neptune Deepwater Port, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Boston, MA.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Safety Zones: Neptune Deepwater Port, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Boston, MA. 165.T01-0542 Section 165.T01-0542 Navigation and Navigable Waters... Guard District § 165.T01-0542 Safety Zones: Neptune Deepwater Port, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Boston, MA. (a...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title33-vol1/pdf/CFR-2012-title33-vol1-sec110-182.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title33-vol1/pdf/CFR-2012-title33-vol1-sec110-182.pdf"><span>33 CFR 110.182 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Fort George Inlet, near Mayport, Fla.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> 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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title33-vol3/pdf/CFR-2010-title33-vol3-sec334-130.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title33-vol3/pdf/CFR-2010-title33-vol3-sec334-130.pdf"><span>33 CFR 334.130 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Wallops Island and Chincoteague Inlet, Va.; danger zone.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Wallops Island and Chincoteague Inlet, Va.; danger zone. 334.130 Section 334.130 Navigation and Navigable Waters... REGULATIONS § 334.130 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Wallops Island and Chincoteague Inlet, Va.; danger zone. (a) The area...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title33-vol2/pdf/CFR-2014-title33-vol2-sec165-714.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title33-vol2/pdf/CFR-2014-title33-vol2-sec165-714.pdf"><span>33 CFR 165.714 - Regulated Navigation Area; <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Charleston, SC.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-07-01</p> <p>... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Regulated Navigation Area; <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Charleston, SC. 165.714 Section 165.714 Navigation and Navigable Waters COAST GUARD... § 165.714 Regulated Navigation Area; <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Charleston, SC. (a) Location. The following area is...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title33-vol3/pdf/CFR-2010-title33-vol3-sec334-390.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title33-vol3/pdf/CFR-2010-title33-vol3-sec334-390.pdf"><span>33 CFR 334.390 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> south of entrance to Chesapeake Bay; firing range.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> south of entrance to Chesapeake Bay; firing range. 334.390 Section 334.390 Navigation and Navigable Waters CORPS OF....390 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> south of entrance to Chesapeake Bay; firing range. (a) The danger zone. A section...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title33-vol3/pdf/CFR-2011-title33-vol3-sec334-390.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title33-vol3/pdf/CFR-2011-title33-vol3-sec334-390.pdf"><span>33 CFR 334.390 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> south of entrance to Chesapeake Bay; firing range.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> south of entrance to Chesapeake Bay; firing range. 334.390 Section 334.390 Navigation and Navigable Waters CORPS OF....390 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> south of entrance to Chesapeake Bay; firing range. (a) The danger zone. A section...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title33-vol3/pdf/CFR-2011-title33-vol3-sec334-580.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title33-vol3/pdf/CFR-2011-title33-vol3-sec334-580.pdf"><span>33 CFR 334.580 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> near Port Everglades, Fla.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> 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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title33-vol3/pdf/CFR-2010-title33-vol3-sec334-580.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title33-vol3/pdf/CFR-2010-title33-vol3-sec334-580.pdf"><span>33 CFR 334.580 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> near Port Everglades, Fla.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> 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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title33-vol3/pdf/CFR-2010-title33-vol3-sec334-525.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title33-vol3/pdf/CFR-2010-title33-vol3-sec334-525.pdf"><span>33 CFR 334.525 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off John F. Kennedy Space Center, FL; restricted area.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off John F. Kennedy Space Center, FL; restricted area. 334.525 Section 334.525 Navigation and Navigable Waters CORPS... REGULATIONS § 334.525 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off John F. Kennedy Space Center, FL; restricted area. (a) The area. The...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title33-vol2/pdf/CFR-2012-title33-vol2-sec165-714.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title33-vol2/pdf/CFR-2012-title33-vol2-sec165-714.pdf"><span>33 CFR 165.714 - Regulated Navigation Area; <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Charleston, SC.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Regulated Navigation Area; <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Charleston, SC. 165.714 Section 165.714 Navigation and Navigable Waters COAST GUARD... § 165.714 Regulated Navigation Area; <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Charleston, SC. (a) Location. The following area is...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title33-vol3/pdf/CFR-2014-title33-vol3-sec334-130.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title33-vol3/pdf/CFR-2014-title33-vol3-sec334-130.pdf"><span>33 CFR 334.130 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Wallops Island and Chincoteague Inlet, Va.; danger zone.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Wallops Island and Chincoteague Inlet, Va.; danger zone. 334.130 Section 334.130 Navigation and Navigable Waters... REGULATIONS § 334.130 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Wallops Island and Chincoteague Inlet, Va.; danger zone. (a) The area...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title33-vol1/pdf/CFR-2013-title33-vol1-sec110-182.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title33-vol1/pdf/CFR-2013-title33-vol1-sec110-182.pdf"><span>33 CFR 110.182 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Fort George Inlet, near Mayport, Fla.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> 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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title33-vol3/pdf/CFR-2011-title33-vol3-sec334-525.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title33-vol3/pdf/CFR-2011-title33-vol3-sec334-525.pdf"><span>33 CFR 334.525 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off John F. Kennedy Space Center, FL; restricted area.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off John F. Kennedy Space Center, FL; restricted area. 334.525 Section 334.525 Navigation and Navigable Waters CORPS... REGULATIONS § 334.525 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off John F. Kennedy Space Center, FL; restricted area. (a) The area. The...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title33-vol3/pdf/CFR-2011-title33-vol3-sec334-130.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title33-vol3/pdf/CFR-2011-title33-vol3-sec334-130.pdf"><span>33 CFR 334.130 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Wallops Island and Chincoteague Inlet, Va.; danger zone.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Wallops Island and Chincoteague Inlet, Va.; danger zone. 334.130 Section 334.130 Navigation and Navigable Waters... REGULATIONS § 334.130 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Wallops Island and Chincoteague Inlet, Va.; danger zone. (a) The area...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title33-vol3/pdf/CFR-2012-title33-vol3-sec334-525.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title33-vol3/pdf/CFR-2012-title33-vol3-sec334-525.pdf"><span>33 CFR 334.525 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off John F. Kennedy Space Center, FL; restricted area.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off John F. Kennedy Space Center, FL; restricted area. 334.525 Section 334.525 Navigation and Navigable Waters CORPS... REGULATIONS § 334.525 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off John F. Kennedy Space Center, FL; restricted area. (a) The area. The...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title33-vol3/pdf/CFR-2014-title33-vol3-sec334-525.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title33-vol3/pdf/CFR-2014-title33-vol3-sec334-525.pdf"><span>33 CFR 334.525 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off John F. Kennedy Space Center, FL; restricted area.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off John F. Kennedy Space Center, FL; restricted area. 334.525 Section 334.525 Navigation and Navigable Waters CORPS... REGULATIONS § 334.525 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off John F. Kennedy Space Center, FL; restricted area. (a) The area. The...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title33-vol3/pdf/CFR-2013-title33-vol3-sec334-525.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title33-vol3/pdf/CFR-2013-title33-vol3-sec334-525.pdf"><span>33 CFR 334.525 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off John F. Kennedy Space Center, FL; restricted area.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off John F. Kennedy Space Center, FL; restricted area. 334.525 Section 334.525 Navigation and Navigable Waters CORPS... REGULATIONS § 334.525 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off John F. Kennedy Space Center, FL; restricted area. (a) The area. The...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title33-vol1/pdf/CFR-2014-title33-vol1-sec110-182.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title33-vol1/pdf/CFR-2014-title33-vol1-sec110-182.pdf"><span>33 CFR 110.182 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Fort George Inlet, near Mayport, Fla.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-07-01</p> <p>... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> 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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title33-vol3/pdf/CFR-2013-title33-vol3-sec334-390.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title33-vol3/pdf/CFR-2013-title33-vol3-sec334-390.pdf"><span>33 CFR 334.390 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> south of entrance to Chesapeake Bay; firing range.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> south of entrance to Chesapeake Bay; firing range. 334.390 Section 334.390 Navigation and Navigable Waters CORPS OF....390 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> south of entrance to Chesapeake Bay; firing range. (a) The danger zone. A section...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title33-vol2/pdf/CFR-2011-title33-vol2-sec165-714.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title33-vol2/pdf/CFR-2011-title33-vol2-sec165-714.pdf"><span>33 CFR 165.714 - Regulated Navigation Area; <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Charleston, SC.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Regulated Navigation Area; <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Charleston, SC. 165.714 Section 165.714 Navigation and Navigable Waters COAST GUARD... § 165.714 Regulated Navigation Area; <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Charleston, SC. (a) Location. The following area is...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2013-09-12/pdf/2013-22135.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2013-09-12/pdf/2013-22135.pdf"><span>78 FR 56151 - Safety Zone, North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>; Virginia Beach, VA</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2013-09-12</p> <p>... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone, North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>; Virginia Beach, VA... zone on the navigable waters of the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> in Virginia Beach, VA to support the Virginia... Delegation No. 0170.1. ] On September 12, 2013 the City of Virginia Beach will host a fireworks display...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2013-06-13/pdf/2013-13993.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2013-06-13/pdf/2013-13993.pdf"><span>78 FR 35596 - Special Local Regulation; Long Beach Regatta, Powerboat Race, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Long Beach, NY</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2013-06-13</p> <p>... Race, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Long Beach, NY AGENCY: Coast Guard, DHS. ACTION: Notice of Proposed Rulemaking... <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Long Beach, NY during the Long Beach Regatta Powerboat Race scheduled for August 24-25, 2013. This action is necessary to provide for the safety of life of participants and spectators...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2013-07-12/pdf/2013-16713.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2013-07-12/pdf/2013-16713.pdf"><span>78 FR 41844 - Safety Zone; Fairfield Estates Fireworks Display, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Sagaponack, NY</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2013-07-12</p> <p>..., <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Sagaponack, NY AGENCY: Coast Guard, DHS. ACTION: Temporary final rule. SUMMARY: The Coast Guard is establishing a temporary safety zone on the navigable waters of the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, in... safety of life on navigable waters during the event. Entering into, transiting through,...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2011-11-04/pdf/2011-28587.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2011-11-04/pdf/2011-28587.pdf"><span>76 FR 68314 - Special Local Regulations; Key West World Championship, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>; Key West, FL</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2011-11-04</p> <p>..., <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>; Key West, FL AGENCY: Coast Guard, DHS. ACTION: Temporary final rule. SUMMARY: The Coast Guard is establishing special local regulations on the waters of the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> located southwest of..., November 13, 2011. These special local regulations are necessary to provide for the safety of life...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2013-11-27/pdf/2013-28360.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2013-11-27/pdf/2013-28360.pdf"><span>78 FR 70901 - Safety Zone; Bone Island Triathlon, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>; Key West, FL</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2013-11-27</p> <p>... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Bone Island Triathlon, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>; Key... proposes to establish a temporary safety zone on the waters of the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> in Key West, Florida... for the safety of life on navigable waters during the event. Persons and vessels are prohibited...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2012-12-26/pdf/2012-30913.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2012-12-26/pdf/2012-30913.pdf"><span>77 FR 75853 - Safety Zone; Bone Island Triathlon, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>; Key West, FL</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2012-12-26</p> <p>... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Bone Island Triathlon, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>; Key... establishing a temporary safety zone on the waters of the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> in Key West, Florida, during the Bone... life on navigable waters during the event. Persons and vessels are prohibited from entering,...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4989309','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4989309"><span>Nitrification and its influence on biogeochemical cycles from the <span class="hlt">equatorial</span> Pacific to the Arctic <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Shiozaki, Takuhei; Ijichi, Minoru; Isobe, Kazuo; Hashihama, Fuminori; Nakamura, Ken-ichi; Ehama, Makoto; Hayashizaki, Ken-ichi; Takahashi, Kazutaka; Hamasaki, Koji; Furuya, Ken</p> <p>2016-01-01</p> <p>We examined nitrification in the euphotic zone, its impact on the nitrogen cycles, and the controlling factors along a 7500 km transect from the <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span> to the Arctic <span class="hlt">Ocean</span>. Ammonia oxidation occurred in the euphotic zone at most of the stations. The gene and transcript abundances for ammonia oxidation indicated that the shallow clade archaea were the major ammonia oxidizers throughout the study regions. Ammonia oxidation accounted for up to 87.4% (average 55.6%) of the rate of nitrate assimilation in the subtropical oligotrophic region. However, in the shallow Bering and Chukchi sea shelves (bottom ⩽67 m), the percentage was small (0–4.74%) because ammonia oxidation and the abundance of ammonia oxidizers were low, the light environment being one possible explanation for the low activity. With the exception of the shallow bottom stations, depth-integrated ammonia oxidation was positively correlated with depth-integrated primary production. Ammonia oxidation was low in the high-nutrient low-chlorophyll subarctic region and high in the Bering Sea Green Belt, and primary production in both was influenced by micronutrient supply. An ammonium kinetics experiment demonstrated that ammonia oxidation did not increase significantly with the addition of 31–1560 nm ammonium at most stations except in the Bering Sea Green Belt. Thus, the relationship between ammonia oxidation and primary production does not simply indicate that ammonia oxidation increased with ammonium supply through decomposition of organic matter produced by primary production but that ammonia oxidation might also be controlled by micronutrient availability as with primary production. PMID:26918664</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26918664','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26918664"><span>Nitrification and its influence on biogeochemical cycles from the <span class="hlt">equatorial</span> Pacific to the Arctic <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shiozaki, Takuhei; Ijichi, Minoru; Isobe, Kazuo; Hashihama, Fuminori; Nakamura, Ken-Ichi; Ehama, Makoto; Hayashizaki, Ken-Ichi; Takahashi, Kazutaka; Hamasaki, Koji; Furuya, Ken</p> <p>2016-09-01</p> <p>We examined nitrification in the euphotic zone, its impact on the nitrogen cycles, and the controlling factors along a 7500 km transect from the <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span> to the Arctic <span class="hlt">Ocean</span>. Ammonia oxidation occurred in the euphotic zone at most of the stations. The gene and transcript abundances for ammonia oxidation indicated that the shallow clade archaea were the major ammonia oxidizers throughout the study regions. Ammonia oxidation accounted for up to 87.4% (average 55.6%) of the rate of nitrate assimilation in the subtropical oligotrophic region. However, in the shallow Bering and Chukchi sea shelves (bottom ⩽67 m), the percentage was small (0-4.74%) because ammonia oxidation and the abundance of ammonia oxidizers were low, the light environment being one possible explanation for the low activity. With the exception of the shallow bottom stations, depth-integrated ammonia oxidation was positively correlated with depth-integrated primary production. Ammonia oxidation was low in the high-nutrient low-chlorophyll subarctic region and high in the Bering Sea Green Belt, and primary production in both was influenced by micronutrient supply. An ammonium kinetics experiment demonstrated that ammonia oxidation did not increase significantly with the addition of 31-1560 nm ammonium at most stations except in the Bering Sea Green Belt. Thus, the relationship between ammonia oxidation and primary production does not simply indicate that ammonia oxidation increased with ammonium supply through decomposition of organic matter produced by primary production but that ammonia oxidation might also be controlled by micronutrient availability as with primary production.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998DSRII..45.1073H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998DSRII..45.1073H"><span>Fluorescence signatures of an iron-enriched phytoplankton community in the eastern <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hoge, Frank E.; Wayne Wright, C.; Swift, Robert N.; Yungel, James K.; Berry, Richard E.; Mitchell, Richard</p> <p></p> <p>Laser-induced fluorescence profiles of chlorophyll and phycoerythrin pigments and chromophoric dissolved organic matter (CDOM) fluorescence acquired over an iron-enriched phytoplankton patch are compared to profiles made over adjacent, naturally occurring phytoplankton patches. A total of four airborne missions were flown during an 8 day period following the release of the iron-rich fertilizer. Analyses of the airborne laser-induced fluorescence profiles from the upper-<span class="hlt">ocean</span> layer reveal: (1) Ship-dispersed iron enhances localized phytoplankton production in high-nutrient/low-chlorophyll regions such as found in the eastern <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span>. (2) The chlorophyll concentration within the iron-enriched phytoplankton patch exceeded levels of chlorophyll found in naturally occurring phytoplankton patches located outside the enriched region. (3) An increase in phycoerythrin fluorescence was observed within the enriched region in correspondence with the elevated chlorophyll fluorescence. However, the phycoerythrin/chlorophyll fluorescence ratio was lower within the enriched patch than in naturally occurring phytoplankton patches outside of the enriched region. (4) No above-background chromorophoric dissolved organic matter (CDOM) fluorescence was observed in the enriched patch. Elevated CDOM fluorescence was associated with some of the naturally occurring phytoplankton patches outside the enriched region, while other such phytoplankton patches showed no measurable increase in CDOM over background levels. (5) The surface layer manifestation of the patch was observed to be transported to the north and west in close agreement with the drogue positions. No elevated surface layer chlorophyll fluorescence was seen in the vicinity of the ship as it sampled the submerged fraction at the time of the 30 October and 1 November overflights. The phycoerythrin pigment fluorescence emission was insensitive to ambient cloud-induced downwelling irradiance variability, while at the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.A21E0175A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.A21E0175A"><span>Systematic errors in Monsoon simulation: importance of the <span class="hlt">equatorial</span> Indian <span class="hlt">Ocean</span> processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Annamalai, H.; Taguchi, B.; McCreary, J. P., Jr.; Nagura, M.; Miyama, T.</p> <p>2015-12-01</p> <p>H. Annamalai1, B. Taguchi2, J.P. McCreary1, J. Hafner1, M. Nagura2, and T. Miyama2 International Pacific Research Center, University of Hawaii, USA Application Laboratory, JAMSTEC, Japan In climate models, simulating the monsoon precipitation climatology remains a grand challenge. Compared to CMIP3, the multi-model-mean (MMM) errors for Asian-Australian monsoon (AAM) precipitation climatology in CMIP5, relative to GPCP observations, have shown little improvement. One of the implications is that uncertainties in the future projections of time-mean changes to AAM rainfall may not have reduced from CMIP3 to CMIP5. Despite dedicated efforts by the modeling community, the progress in monsoon modeling is rather slow. This leads us to wonder: Has the scientific community reached a "plateau" in modeling mean monsoon precipitation? Our focus here is to better understanding of the coupled air-sea interactions, and moist processes that govern the precipitation characteristics over the tropical Indian <span class="hlt">Ocean</span> where large-scale errors persist. A series idealized coupled model experiments are performed to test the hypothesis that errors in the coupled processes along the <span class="hlt">equatorial</span> Indian <span class="hlt">Ocean</span> during inter-monsoon seasons could potentially influence systematic errors during the monsoon season. Moist static energy budget diagnostics has been performed to identify the leading moist and radiative processes that account for the large-scale errors in the simulated precipitation. As a way forward, we propose three coordinated efforts, and they are: (i) idealized coupled model experiments; (ii) process-based diagnostics and (iii) direct observations to constrain model physics. We will argue that a systematic and coordinated approach in the identification of the various interactive processes that shape the precipitation basic state needs to be carried out, and high-quality observations over the data sparse monsoon region are needed to validate models and further improve model physics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhDT.......148M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhDT.......148M"><span>The Indian <span class="hlt">Ocean</span> Dipole's influence on <span class="hlt">Atlantic</span> tropical cyclone activity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marinaro, Alan Joseph</p> <p></p> <p>Improving early tropical cyclone forecasts would assist reinsurance decision makers as they seek information that can minimize risks. Early lead forecasts are based on model variables before December 1 (Year 0) that predict <span class="hlt">Atlantic</span> tropical cyclone activity (Year +1). The autumn Indian <span class="hlt">Ocean</span> Dipole (IOD) has an 8 to 14 month antecedent correlation with the El Nino - Southern Oscillation (ENSO). ENSO is traditionally the best non-lead and overall predictor of <span class="hlt">Atlantic</span> tropical cyclone activity. Analyses were performed over a 30-year period from 1984/85-2013/14, with some time variation depending on the test. Correlation, spatial, and wavelet analyses were utilized to find associations between the IOD, west and east components of the IOD, and four other variables related to the following season's ENSO state and tropical cyclone activity. The prior western pole of the October IOD (WIOD) was demonstrated to have statistically significant r-squared values (i.e. 99% confidence interval) to upcoming tropical storm activity (i.e. explained 25% of the variance), named storm counts (28%), and ENSO (21%). The WIOD has no connection with U.S. hurricane landfalls. Wavelet analysis between October IOD variables and following August-October ENSO data was observed to have the best time-frequency relationship. Dynamic reasoning for these relationships reside within the idealized biennial IOD-ENSO cycle, Walker circulation process, and the impact of ENSO on the state of the <span class="hlt">Atlantic</span> Basin. The WIOD's integration into early-lead forecast models could be an advantage for those in the reinsurance industry and other decision makers impacted by <span class="hlt">Atlantic</span> tropical cyclonesn.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PApGe.170.1913P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PApGe.170.1913P"><span>Long Wave Resonance in Tropical <span class="hlt">Oceans</span> and Implications on Climate: the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pinault, Jean-Louis</p> <p>2013-11-01</p> <p> Kelvin wave, being deflected off the western boundary. The succession of warm and cold waters transferred by baroclinic waves during a cycle leaves the tropical <span class="hlt">ocean</span> by radiation and contributes to western boundary currents. The main manifestation of the basin modes concerns the variability of the NECC, of the branch of the South <span class="hlt">Equatorial</span> Current (SEC) along the equator, of the western boundary currents as well as the formation of remote resonances, as will be presented in a future work. Remote resonances occur at midlatitudes, the role of which is suspected of being crucial in the functioning of subtropical gyres and in climate variability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014DSRI...89...56G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014DSRI...89...56G"><span>Factors influencing particulate lipid production in the East <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gašparović, B.; Frka, S.; Koch, B. P.; Zhu, Z. Y.; Bracher, A.; Lechtenfeld, O. J.; Neogi, S. B.; Lara, R. J.; Kattner, G.</p> <p>2014-07-01</p> <p>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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>. 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 <span class="hlt">ocean</span> surface (2 m depth and deep Chl a maximum (DCM). Samples from the deep <span class="hlt">ocean</span> 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 <span class="hlt">Atlantic</span> Tropical Gyral Province (13-25°N). Factors responsible for the enhanced lipid synthesis in the eastern <span class="hlt">Atlantic</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24730134','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24730134"><span>Iron bacterial phylogeny and their execution towards iron availability in <span class="hlt">Equatorial</span> Indian <span class="hlt">Ocean</span> and coastal Arabian Sea.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rajasabapathy, Raju; Mohandass, Chellandi; Vijayaraj, Ajakkalamoole Srinivas; Madival, Varsha Vinayak; Meena, Ram Murti</p> <p>2013-01-01</p> <p>Based on distinct colony morphology, color, size, shape and certain other traits, 92 bacterial isolates were investigated to understand their managerial ability on iron from the Arabian Sea and <span class="hlt">Equatorial</span> Indian <span class="hlt">Ocean</span> samples. The ARDRA (amplified rDNA restriction analysis) applied to eliminate the duplication of the bacterial strains, resulted 39 different banding patterns. The 16S rRNA gene sequencing data indicate the dominancy of three phylogenetic groups, alpha-Proteobacteria (10.25%), gamma-Proteobacteria (35.89%) and Bacilli (53.84%) in these waters. Marinobacter and Bacillus were the only common genera from both of the regions. Pseudoalteromonas, Halomonas, Rheinheimera, Staphylococcus and Idiomarina were some of the other genera obtained from the Arabian Sea. Erythrobacter, Roseovarius, Sagittula and Nitratireductor were found mostly in <span class="hlt">Equatorial</span> Indian <span class="hlt">Ocean</span>. In addition, 16S rRNA gene sequence data of some of our iron bacterial strains belong to novel species and one isolate ASS2A could form a new genus. Close to 23% of the isolates were able to produce high affinity sets of ligands like siderophores to mediate iron transport into the cell. The current study indicated that the <span class="hlt">Equatorial</span> Indian <span class="hlt">Ocean</span> species were well adapted to oxidize iron as an electron acceptor and the Arabian Sea species preferably go through siderophore production.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMIN13D..05V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMIN13D..05V"><span>Are Global In-Situ <span class="hlt">Ocean</span> Observations Fit-for-purpose? Applying the Framework for <span class="hlt">Ocean</span> Observing in the <span class="hlt">Atlantic</span>.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Visbeck, M.; Fischer, A. S.; Le Traon, P. Y.; Mowlem, M. C.; Speich, S.; Larkin, K.</p> <p>2015-12-01</p> <p>There are an increasing number of global, regional and local processes that are in need of integrated <span class="hlt">ocean</span> information. In the sciences <span class="hlt">ocean</span> information is needed to support physical <span class="hlt">ocean</span> 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 <span class="hlt">Ocean</span> Assessment focuses more on ecosystem services and there is an expectation that the Sustainable Development Goals and in particular Goal 14 on the <span class="hlt">Ocean</span> and Seas will generate new demands for integrated <span class="hlt">ocean</span> observing from Climate to Fish and from <span class="hlt">Ocean</span> Resources to Safe Navigation and on a healthy, productive and enjoyable <span class="hlt">ocean</span> in more general terms. In recognition of those increasing needs for integrated <span class="hlt">ocean</span> information we have recently launched the Horizon 2020 <span class="hlt">Atlant</span>OS project to promote the transition from a loosely-coordinated set of existing <span class="hlt">ocean</span> observing activities to a more integrated, more efficient, more sustainable and fit-for-purpose <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> Observing System. <span class="hlt">Atlant</span>OS takes advantage of the Framework for <span class="hlt">Ocean</span> observing that provided strategic guidance for the design of the project and its outcome. <span class="hlt">Atlant</span>OS will advance the requirements and systems design, improving the readiness of observing networks and data systems, and engaging stakeholders around the <span class="hlt">Atlantic</span>. <span class="hlt">Atlant</span>OS will bring <span class="hlt">Atlantic</span> nations together to strengthen their complementary contributions to and benefits from the internationally coordinated Global <span class="hlt">Ocean</span> Observing System (GOOS) and the Blue Planet Initiative of the Global Earth Observation System of Systems (GEOSS). <span class="hlt">Atlant</span>OS will fill gaps of the in-situ observing system networks and will ensure that their data are readily accessible and useable. <span class="hlt">Atlant</span>OS will demonstrate the utility of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PrOce.156....1G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PrOce.156....1G"><span>The seasonal march of the <span class="hlt">equatorial</span> Pacific upper-<span class="hlt">ocean</span> and its El Niño variability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gasparin, Florent; Roemmich, Dean</p> <p>2017-08-01</p> <p>Based on two modern data sets, the climatological seasonal march of the upper-<span class="hlt">ocean</span> is examined in the <span class="hlt">equatorial</span> Pacific for the period 2004-2014, because of its large contribution to the total variance, its relationship to El Niño, and its unique <span class="hlt">equatorial</span> wave phenomena. Argo provides a broadscale view of the <span class="hlt">equatorial</span> Pacific upper-<span class="hlt">ocean</span> based on subsurface temperature and salinity measurements for the period 2004-2015, and satellite altimetry provides synoptic observations of the sea surface height (SSH) for the period 1993-2015. Using either 11-year (1993-2003/2004-2014) time-series for averaging, the seasonal Rossby waves stands out clearly and eastward intraseasonal Kelvin wave propagation is strong enough in individual years to leave residuals in the 11-year averages, particularly but not exclusively, during El Niño onset years. The agreement of altimetric SSH minus Argo steric height (SH) residuals with GRACE <span class="hlt">ocean</span> mass estimates confirms the scale-matching of in situ variability with that of satellite observations. Surface layer and subsurface thermohaline variations are both important in determining SH and SSH basin-wide patterns. The SH/SSH October-November maximum in the central-eastern Pacific is primarily due to a downward deflection of the thermocline (∼20 m), causing a warm subsurface anomaly (>1 °C), in response to the phasing of downwelling intraseasonal Kelvin and seasonal Rossby waves. Compared with the climatology, the stronger October-November maximum in the 2004-2014 El Niño composites is due to higher intraseasonal oscillations and interannual variability. Associated with these <span class="hlt">equatorial</span> wave patterns along the thermocline, the western warm/fresh pool waters move zonally at interannual timescales through zonal wind stress and pressure gradient fluctuations, and cause substantial fresh (up to 0.6 psu) and warm (∼1 °C higher than the climatology) anomalies in the western-central Pacific surface-layer during the El Niño onset</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1712816A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1712816A"><span>A description of eddy-mean flow feedbacks in <span class="hlt">equatorial</span> and boundary current systems of the South Indian <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aguiar-González, Borja; Ponsoni, Leandro; Maas, Leo R. M.; Ridderinkhof, Herman; van Aken, Hendrik</p> <p>2015-04-01</p> <p> accelerating alongstream eddy forces and kinetic energy being transferred from the eddy field to the mean flow. This is the case for 1) the meandering Indonesian Throughflow, ITF (winter and spring); 2) the southward along-slope flow crossing the narrows of the Mozambique Channel and shedding anticyclonic eddies; 3) the southern South East Madagascar Current shedding dipoles; and, 4) the Agulhas Retroflection, shedding Agulhas rings into the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>. Additionally, we observe a well-known feature of the eastward-flowing Agulhas Return Current and the ACC, also along the South <span class="hlt">Equatorial</span> Countercurrent, the ITF and the North East Madagascar Current. In all cases (either eastward- or westward-flowing), these nearly zonal currents exhibit convergence (divergence) of the cross-stream eddy momentum forces acting over its left-hand (right-hand) side, looking downstream, pointing to a systematic drift of the mean flow towards its left-hand side by cross-stream eddy forces. Quantitative estimates and qualitative spatial patterns from this study provide a unique tool for testing the performance of eddy-resolving models on predicting realistically eddy-mean flow feedbacks in the SIO.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.A12C..01N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.A12C..01N"><span>The dynamics of wind-driven intraseasonal variability in the <span class="hlt">equatorial</span> Indian <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nagura, M.; McPhaden, M. J.</p> <p>2012-12-01</p> <p>Variability in the <span class="hlt">equatorial</span> Indian <span class="hlt">Ocean</span> on intraseasonal time scales (defined as periods of 30-110 days) is investigated using satellite and in situ observations and a simple analytical linear long-wave <span class="hlt">equatorial</span> beta-plane model. Despite the extreme simplicity of the model, which includes just the two gravest baroclinic mode Kelvin waves and first meridional mode Rossby waves, simulated surface zonal velocity and sea surface height compare very well with observations. Both observations and model are characterized by a red shift in the velocity spectrum relative to the wind forcing spectrum (Figure 1), which is attributable to a combination of factors, including (1) the near resonant excitation of Kelvin waves by eastward propagating winds, (2) constructive interference between wind-forced waves and Rossby waves reflected from the eastern boundary, and (3) the favored excitation of low-frequency waves whose zonal wavelengths are long compared to the zonal fetch of the wind. We decomposed variability in two broad period bands, namely, 30-70 days and 70-110 days, for detailed analysis. At periods of 30-70 days, zonal velocity tends to be stationary in the directly forced region along the equator owing to the competing contributions of Kelvin and Rossby waves. In contrast, at 70-110 day periods, zonal velocity propagates westward despite eastward propagation of zonal wind stress because of the combined influence of eastern boundary generated and wind-forced Rossby waves. Kelvin waves reflected from the western boundary are negligibly small, indicating that basin mode resonances are not prominent as has been previously suggested.igure 1: Variance preserving spectra at 0°, 80°E for (a) QSCAT zonal wind stress and (b) zonal velocity at 15 m depth from the analytic model (solid line), OSCAR (dotted line), and ADCP observations (dashed line). A triangle filter for three adjacent spectral estimates was applied 10 times to smooth the spectra. The dark shades represent</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011DSRII..58..311P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011DSRII..58..311P"><span>Estimating iron and aluminum removal rates in the eastern <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span> using a box model approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Palacz, Artur P.; Chai, Fei; Dugdale, Richard C.; Measures, Christopher I.</p> <p>2011-03-01</p> <p>Iron limitation plays an important role in maintaining the high-nitrate low-chlorophyll (HNLC) condition in the <span class="hlt">equatorial</span> upwelling zone. The rate and depth of upwelling control Fe supply to the euphotic zone. This study constrains the transport fluxes and budget of two trace metals, Fe and Al, in the upper <span class="hlt">ocean</span>. They are co-delivered to the eastern <span class="hlt">equatorial</span> Pacific surface waters via the <span class="hlt">Equatorial</span> Undercurrent and upwelling but show distinct biogeochemical cycling processes. We combine the results of the in situ measurements of dissolved Fe and Al (dFe and dAl) with the modeled velocity fields to calculate the physical fluxes. The model calculations are evaluated with the conservation of heat, volume transport, NO 3 and Si(OH) 4 budgets for the <span class="hlt">equatorial</span> Pacific. The vertical flux due to upwelling provides averaged dFe and dAl supply rates of 1.45 μmol m -2 d -1 and 11.51 μmol m -2 d -1, respectively. The sum of the net physical fluxes in the eastern <span class="hlt">equatorial</span> Pacific for dFe and dAl are 0.41 μmol m -2 d -1 and 2.77 μmol m -2 d -1, respectively. These estimates are equal to the net biological and chemical removal rates of dFe and dAl. The calculated dFe:C net removal ratio is in the range of 3-9 μmol:mol, which agrees with most other estimates. This suggests that the majority of net dFe removal is due to biological uptake in the upper water column. The results of this box model approach illustrate the usefulness of combining the modeled outputs and in situ measurements, which provide additional constraints on Fe transport and cycling in the <span class="hlt">equatorial</span> Pacific and possibly other HNLC regions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2012-03-14/pdf/2012-6182.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2012-03-14/pdf/2012-6182.pdf"><span>77 FR 15006 - Special Local Regulations; Third Annual Space Coast Super Boat Grand Prix, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Cocoa...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2012-03-14</p> <p>... Super Boat Grand Prix, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Cocoa Beach, FL AGENCY: Coast Guard, DHS. ACTION: Notice of... of the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> east of Cocoa Beach, Florida during the Third Annual Space Coast Super Boat...-speed boat races. The event will be held on the waters of the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> east of Cocoa Beach...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title33-vol3/pdf/CFR-2011-title33-vol3-sec334-590.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title33-vol3/pdf/CFR-2011-title33-vol3-sec334-590.pdf"><span>33 CFR 334.590 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Cape Canaveral, Fla.; Air Force missile testing area, Patrick Air Force Base...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Cape Canaveral... RESTRICTED AREA REGULATIONS § 334.590 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Cape Canaveral, Fla.; Air Force missile testing area, Patrick Air Force Base, Fla. (a) The danger zone. An area in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> immediately offshore from...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title33-vol3/pdf/CFR-2012-title33-vol3-sec334-500.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title33-vol3/pdf/CFR-2012-title33-vol3-sec334-500.pdf"><span>33 CFR 334.500 - St. Johns River, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Sherman Creek; restricted areas and danger zone, Naval Station...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false St. Johns River, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>... AND RESTRICTED AREA REGULATIONS § 334.500 St. Johns River, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Sherman Creek; restricted... area and the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> restricted area described in paragraphs (a)(2) and (a)(3) of this section...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title33-vol3/pdf/CFR-2010-title33-vol3-sec334-500.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title33-vol3/pdf/CFR-2010-title33-vol3-sec334-500.pdf"><span>33 CFR 334.500 - St. Johns River, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Sherman Creek; restricted areas and danger zone, Naval Station...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false St. Johns River, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>... AND RESTRICTED AREA REGULATIONS § 334.500 St. Johns River, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Sherman Creek; restricted... area and the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> restricted area described in paragraphs (a)(2) and (a)(3) of this section...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title33-vol3/pdf/CFR-2012-title33-vol3-sec334-590.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title33-vol3/pdf/CFR-2012-title33-vol3-sec334-590.pdf"><span>33 CFR 334.590 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Cape Canaveral, Fla.; Air Force missile testing area, Patrick Air Force Base...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2012-07-01 2012-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Cape Canaveral... RESTRICTED AREA REGULATIONS § 334.590 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Cape Canaveral, Fla.; Air Force missile testing area, Patrick Air Force Base, Fla. (a) The danger zone. An area in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> immediately offshore from...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title33-vol3/pdf/CFR-2011-title33-vol3-sec334-500.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title33-vol3/pdf/CFR-2011-title33-vol3-sec334-500.pdf"><span>33 CFR 334.500 - St. Johns River, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Sherman Creek; restricted areas and danger zone, Naval Station...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2011-07-01 2011-07-01 false St. Johns River, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>... AND RESTRICTED AREA REGULATIONS § 334.500 St. Johns River, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Sherman Creek; restricted... area and the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> restricted area described in paragraphs (a)(2) and (a)(3) of this section...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title33-vol3/pdf/CFR-2013-title33-vol3-sec334-500.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title33-vol3/pdf/CFR-2013-title33-vol3-sec334-500.pdf"><span>33 CFR 334.500 - St. Johns River, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Sherman Creek; restricted areas and danger zone, Naval Station...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false St. Johns River, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>... AND RESTRICTED AREA REGULATIONS § 334.500 St. Johns River, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Sherman Creek; restricted... area and the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> restricted area described in paragraphs (a)(2) and (a)(3) of this section...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title33-vol3/pdf/CFR-2010-title33-vol3-sec334-590.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title33-vol3/pdf/CFR-2010-title33-vol3-sec334-590.pdf"><span>33 CFR 334.590 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Cape Canaveral, Fla.; Air Force missile testing area, Patrick Air Force Base...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Cape Canaveral... RESTRICTED AREA REGULATIONS § 334.590 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Cape Canaveral, Fla.; Air Force missile testing area, Patrick Air Force Base, Fla. (a) The danger zone. An area in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> immediately offshore from...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title33-vol3/pdf/CFR-2014-title33-vol3-sec334-590.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title33-vol3/pdf/CFR-2014-title33-vol3-sec334-590.pdf"><span>33 CFR 334.590 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Cape Canaveral, Fla.; Air Force missile testing area, Patrick Air Force Base...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Cape Canaveral... RESTRICTED AREA REGULATIONS § 334.590 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Cape Canaveral, Fla.; Air Force missile testing area, Patrick Air Force Base, Fla. (a) The danger zone. An area in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> immediately offshore from...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title33-vol3/pdf/CFR-2013-title33-vol3-sec334-590.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title33-vol3/pdf/CFR-2013-title33-vol3-sec334-590.pdf"><span>33 CFR 334.590 - <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Cape Canaveral, Fla.; Air Force missile testing area, Patrick Air Force Base...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2013-07-01 2013-07-01 false <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Cape Canaveral... RESTRICTED AREA REGULATIONS § 334.590 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> off Cape Canaveral, Fla.; Air Force missile testing area, Patrick Air Force Base, Fla. (a) The danger zone. An area in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> immediately offshore from...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title33-vol3/pdf/CFR-2014-title33-vol3-sec334-500.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title33-vol3/pdf/CFR-2014-title33-vol3-sec334-500.pdf"><span>33 CFR 334.500 - St. Johns River, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Sherman Creek; restricted areas and danger zone, Naval Station...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-07-01</p> <p>... 33 Navigation and Navigable Waters 3 2014-07-01 2014-07-01 false St. Johns River, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>... AND RESTRICTED AREA REGULATIONS § 334.500 St. Johns River, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Sherman Creek; restricted... area and the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> restricted area described in paragraphs (a)(2) and (a)(3) of this section...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title33-vol2/pdf/CFR-2013-title33-vol2-sec162-65.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title33-vol2/pdf/CFR-2013-title33-vol2-sec162-65.pdf"><span>33 CFR 162.65 - All waterways tributary to the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> south of Chesapeake Bay and all waterways tributary...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>... <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> south of Chesapeake Bay and all waterways tributary to the Gulf of Mexico east and south of... All waterways tributary to the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> south of Chesapeake Bay and all waterways tributary to..., which are tributary to or connected by other waterways with the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> south of Chesapeake...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JMS...150...56A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JMS...150...56A"><span>Temporal changes in total and size-fractioned chlorophyll-a in surface waters of three provinces in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> (September to November) between 2003 and 2010</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Agirbas, Ertugrul; Martinez-Vicente, Victor; Brewin, Robert J. W.; Racault, Marie-Fanny; Airs, Ruth L.; Llewellyn, Carole A.</p> <p>2015-10-01</p> <p>Phytoplankton total chlorophyll concentration (TCHLa) and phytoplankton size structure are two important ecological indicators in biological oceanography. Using high performance liquid chromatography (HPLC) pigment data, collected from surface waters along the <span class="hlt">Atlantic</span> Meridional Transect (AMT), we examine temporal changes in TCHLa and phytoplankton size class (PSC: micro-, nano- and pico-phytoplankton) between 2003 and 2010 (September to November cruises only), in three ecological provinces of the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>. The HPLC data indicate no significant change in TCHLa in northern and <span class="hlt">equatorial</span> provinces, and an increase in the southern province. These changes were not significantly different to changes in TCHLa derived using satellite <span class="hlt">ocean</span>-colour data over the same study period. Despite no change in AMT TCHLa in northern and <span class="hlt">equatorial</span> provinces, significant differences in PSC were observed, related to changes in key diagnostic pigments (fucoxanthin, peridinin, 19‧-hexanoyloxyfucoxanthin and zeaxanthin), with an increase in small cells (nano- and pico-phytoplankton) and a decrease in larger cells (micro-phytoplankton). When fitting a three-component model of phytoplankton size structure - designed to quantify the relationship between PSC and TCHLa to each AMT cruise, model parameters varied over the study period. Changes in the relationship between PSC and TCHLa have wide implications in ecology and marine biogeochemistry, and provide key information for the development and use of empirical <span class="hlt">ocean</span>-colour algorithms. Results illustrate the importance of maintaining a time-series of in-situ observations in remote regions of the <span class="hlt">ocean</span>, such as that acquired in the AMT programme.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016cosp...41E1561P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E1561P"><span>THEOS-2 Orbit Design: Formation Flying in <span class="hlt">Equatorial</span> Orbit and Damage Prevention Technique for the South <span class="hlt">Atlantic</span> Magnetic Anomaly (SAMA)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pimnoo, Ammarin</p> <p>2016-07-01</p> <p>Geo-Informatics and Space Technology Development Agency (GISTDA) has initiative THEOS-2 project after the THEOS-1 has been operated for more than 7 years which is over the lifetime already. THEOS-2 project requires not only the development of earth observation satellite(s), but also the development of the area-based decision making solution platform comprising of data, application systems, data processing and production system, IT infrastructure improvement and capacity building through development of satellites, engineering model, and infrastructures capable of supporting research in related fields. The developing satellites in THEOS-2 project are THAICHOTE-2 and THAICHOTE-3. This paper focuses the orbit design of THAICHOTE-2 & 3. It discusses the satellite orbit design for the second and third EOS of Thailand. In this paper, both THAICHOTE will be simulated in an <span class="hlt">equatorial</span> orbit as a formation flying which will be compared the productive to THAICHOTE-1 (THEOS-1). We also consider a serious issue in <span class="hlt">equatorial</span> orbit design, namely the issue of the geomagnetic field in the area of the eastern coast of South America, called the South <span class="hlt">Atlantic</span> Magnetic Anomaly (SAMA). The high-energy particles of SAMA comprise a radiation environment which can travel through THAICHOTE-2 & 3 material and deposit kinetic energy. This process causes atomic displacement or leaves a stream of charged atoms in the incident particles' wake. It can cause damage to the satellite including reduction of power generated by solar arrays, failure of sensitive electronics, increased background noise in sensors, and exposure of the satellite devices to radiation. This paper demonstrates the loss of ionizing radiation damage and presents a technique to prevent damage from high-energy particles in the SAMA.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012BGeo....9.4099M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012BGeo....9.4099M"><span>Mass, nutrient and oxygen budgets for the northeastern <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maze, G.; Mercier, H.; Thierry, V.; Memery, L.; Morin, P.; Perez, F. F.</p> <p>2012-10-01</p> <p>The northeast <span class="hlt">Atlantic</span> is a key horizontal and vertical crossroads region for the meridional overturning circulation, but basic nutrient and oxygen fluxes are still poorly constrained by observations in the region. A surface to bottom northeast <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> budget for mass, nutrients (nitrate and phosphate) and oxygen is determined using an optimization method based on three surveys of the OVIDE transect (from Greenland to Portugal) completed with the World <span class="hlt">Ocean</span> Atlas 2009. Budgets are derived for two communicating boxes representing the northeastern European basin (NEEB) and the Irminger Sea. For the NEEB (Irminger) box, it is found that 30% of the mass import (export) across the OVIDE section reach (originate from) the Nordic Seas, while 70% are redistributed between both boxes through the Reykjanes Ridge (9.3 ± 0.7 × 109 kg s-1). Net biological source/sink terms of nitrate point to both the Irminger and NEEB boxes as net organic matter production sites (consuming nitrate at a rate of -7.8 ± 6.5 kmol s-1 and -8.4 ± 6.6 kmol s-1, respectively). Using a standard Redfield ratio of C : N = 106 : 16, nitrate consumption rates indicate that about 40 TgC yr-1 of carbon is fixed by organic matter production between the OVIDE transect and the Greenland-Scotland Ridge. Nutrient fluxes also induce a net biological production of oxygen of 73 ± 60 kmol s-1 and 79 ± 62 kmol s-1 in the Irminger and NEEB boxes, which points to the region as being autotrophic. The abiotic air-sea oxygen flux leads to an <span class="hlt">oceanic</span> oxygen uptake in the two regions (264 ± 66 kmol s-1 in the north and 443 ± 70 kmol s-1 in the south). The abiotic flux is partitioned into a mixing and a thermal component. It is found that the Irminger Sea <span class="hlt">oceanic</span> oxygen uptake is driven by an air-sea heat flux cooling increasing the <span class="hlt">ocean</span> surface oxygen solubility. Over the northeastern European basin the mixing component is about half the thermal flux, presumably because of the oxygen minimum in the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUSMOS24A..02S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUSMOS24A..02S"><span><span class="hlt">Ocean</span>-Atmosphere coupling and CO2 exchanges in the Southwestern <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Souza, R.; Pezzi, L. P.; Carmargo, R.; Acevedo, O. C.</p> <p>2013-05-01</p> <p>The establishment of the INTERCONF Program (Air-Sea Interactions at the Brazil-Malvinas Confluence Zone) in 2004 and subsequent developing of projects such as the SIMTECO (Integrated System for Monitoring the Weather, the Climate and the <span class="hlt">Ocean</span> in the South of Brazil) and ACEx (<span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> Carbon Experiment) from 2010 in Brazil brought to light the importance of understanding the impact of the Southwestern <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>'s mesoscale variability on the modulation of the atmospheric boundary layer (ABL) at the synoptic scale. Recent results of all these projects showed that the ABL modulation, as well as the <span class="hlt">ocean</span>-atmosphere turbulent (heat, momentum and CO2) fluxes are dependent on the behavior of the <span class="hlt">ocean</span>'s surface thermal gradients, especially those found in the Brazil-Malvinas Confluence Zone and at the southern coast off Brazil during the winter. As expected, when atmospheric large scale systems are not present over the study area, stronger heat fluxes are found over regions of higher sea surface temperature (SST) including over warm core eddies shed towards the subantarctic (cold) environment. In the coastal region off southern Brazil, the wintertime propagation of the Brazilian Costal Current (La Plata Plume) acts rising the chlorophyll concentration over the continental shelf as well as diminishing considerably the SST - hence producing prominent across-shore SST gradients towards the offshore region dominated by the Brazil Current waters. Owing to that, heat fluxes are directed towards the <span class="hlt">ocean</span> in coastal waters that are also responsible for the carbon sinking off Brazil in wintertime. All this description is dependent on the synoptic atmospheric cycle and strongly perturbed when transient systems (cold fronts, subtropical cyclones) are present in the area. However, remote sensing data used here suggest that the average condition of the atmosphere directly responding to the <span class="hlt">ocean</span>'s mesoscale variability appears to imprint a signal that extends from the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985JGR....90.6903B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985JGR....90.6903B"><span>The Transient Tracers in the <span class="hlt">Ocean</span> (TTO) program: The North <span class="hlt">Atlantic</span> Study, 1981; The Tropical <span class="hlt">Atlantic</span> Study, 1983</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brewer, Peter G.; Sarmiento, Jorge L.; Smethie, William M.</p> <p>1985-01-01</p> <p>The scientific papers here collected result from the Transient Tracers in the <span class="hlt">Ocean</span> (TTO) program. The two parts of this major geochemical and physical oceanographie expedition took place in the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> in 1981 and in the Tropical <span class="hlt">Atlantic</span> in 1983 on the research vessel Knorr of the Woods Hole Oceanographie Institution. The expeditions, sponsored by the National Science Foundation and the U.S. Department of Energy (North <span class="hlt">Atlantic</span> only), were designed to observe the passage of man-made geochemical tracers into the interior of the <span class="hlt">ocean</span>. The foundations for such an experiment were laid in the 1972-1978 GEOSECS program. Here, for the first time, a systematic survey revealed the penetration into the thermocline and deep <span class="hlt">ocean</span> of the products of man's military/industrial activities, principally tritium and carbon-14 resulting from atmospheric testing of nuclear weapons, which terminated with the nuclear test ban treaty in 1962.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMOS53A2105R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMOS53A2105R"><span>Sea surface salinity fronts in the Tropical <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ruiz-Etcheverry, L.; Maximenko, N. A.; Melnichenko, O.</p> <p>2016-12-01</p> <p>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 <span class="hlt">ocean</span>-atmosphere system, particularly in the tropical <span class="hlt">oceans</span>. 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 <span class="hlt">Atlantic</span>. 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 <span class="hlt">ocean</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-99PP-1036&hterms=atlantic+ocean+mercury&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Datlantic%2Bocean%2Bmercury','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-99PP-1036&hterms=atlantic+ocean+mercury&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Datlantic%2Bocean%2Bmercury"><span>Liberty Bell 7 is retrieved from <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1999-01-01</p> <p>A close-up of the recently recovered Liberty Bell 7 Project Mercury capsule from the <span class="hlt">ocean</span> floor shows the lettering 'United States' still clearly visible on its side. Thirty-eight years ago, the capsule made a successful 16-minute suborbital flight, with astronaut Virgil 'Gus' Grissom aboard, and splashed down in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>. 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 <span class="hlt">ocean</span> floor, until now. In an expedition sponsored by the Discovery Channel, underwater salvage expert Curt Newport fulfilled a 14-year dream in finding and, after one abortive attempt, successfully raising the capsule and bringing it to Port Canaveral. 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-99PP-1030&hterms=ocean+floor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Docean%2Bfloor','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-99PP-1030&hterms=ocean+floor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Docean%2Bfloor"><span>Liberty Bell 7 is retrieved from <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1999-01-01</p> <p>Retrieved from the <span class="hlt">ocean</span> 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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>. 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 <span class="hlt">ocean</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-99PP-1036&hterms=ocean+floor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Docean%2Bfloor','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-99PP-1036&hterms=ocean+floor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Docean%2Bfloor"><span>Liberty Bell 7 is retrieved from <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1999-01-01</p> <p>A close-up of the recently recovered Liberty Bell 7 Project Mercury capsule from the <span class="hlt">ocean</span> floor shows the lettering 'United States' still clearly visible on its side. Thirty-eight years ago, the capsule made a successful 16-minute suborbital flight, with astronaut Virgil 'Gus' Grissom aboard, and splashed down in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>. 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 <span class="hlt">ocean</span> floor, until now. In an expedition sponsored by the Discovery Channel, underwater salvage expert Curt Newport fulfilled a 14-year dream in finding and, after one abortive attempt, successfully raising the capsule and bringing it to Port Canaveral. 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.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMPP53A2376C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMPP53A2376C"><span>Late Quaternary carbonate accumulation along eastern South <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Crabill, K.; Slowey, N. C.; Foreman, A. D.; Charles, C.</p> <p>2016-12-01</p> <p>Water masses originating from both the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> and the Southern <span class="hlt">Ocean</span> 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 <span class="hlt">ocean</span> circulation/climate have occurred during intervals of the last glacial-interglacial cycle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=KSC-99PP-1030&hterms=deep+dream&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Ddeep%2Bdream','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=KSC-99PP-1030&hterms=deep+dream&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Ddeep%2Bdream"><span>Liberty Bell 7 is retrieved from <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1999-01-01</p> <p>Retrieved from the <span class="hlt">ocean</span> 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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>. 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 <span class="hlt">ocean</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27470828','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27470828"><span>A new species of Anthiadinae (Teleostei: Serranidae) from São Pedro and São Paulo Archipelago, Brazil, <span class="hlt">Equatorial</span> <span class="hlt">Atlantic</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Carvalho-Filho, Alfredo; Macena, Bruno César Luz; Nunes, Diogo Martins</p> <p>2016-07-22</p> <p>A new species of Anthiadinae, Odontanthias cauoh, is described from São Pedro and São Paulo Archipelago (SPSPA), Brazil, <span class="hlt">Equatorial</span> <span class="hlt">Atlantic</span>. The new species differs from its only <span class="hlt">Atlantic</span> congener by a combination of several characters: pectoral-fin rays 20; total gill rakers on first arch 39; vomerine tooth patch with a posterior prolongation; pelvic fin not reaching base of last anal-fin ray; dorsal, anal and pelvic fins scaleless; and coloration (dorsal, anal, and pelvic fins mostly dark red). The record of the new species contributes to increase the fish endemism in SPSPA.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-sl4-142-4577.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-sl4-142-4577.html"><span>South Georgia Island in the South <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>1974-02-28</p> <p>SL4-142-4577 (28 Jan. 1974) --- Two large ice islands in the vicinity of South Georgia Island in the South <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, as photographed from the Skylab space station in Earth orbit by one of the Skylab 4 crewmen. The camera used was a hand-held 70mm Hasselblad, with SO-368 medium-speed Ektachrome. One of the ice islands is partially obscured by clouds. Ice islands were observed as large as 45 by 60 kilometers (27 x 37 miles) and as far north as 45 degrees south latitude. The size and distribution of the "small" icebergs (to a ship they would look very large) can be used to study the local winds and currents. Recent research has suggested the possibility of towing such Antarctic icebergs to selected areas and using them as water supplies. One such iceberg would contain many times the water as in Lake Powell. Photo credit: NASA</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1988GeoRL..15.1393C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988GeoRL..15.1393C"><span>Sulfide in surface waters of the western <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cutter, Gregory A.; Krahforst, Christian F.</p> <p>1988-11-01</p> <p>Using newly developed techniques, some preliminary data on hydrogen sulfide in surface waters of the western <span class="hlt">Atlantic</span> have been obtained. Concentrations of total sulfide range from <0.1 to 1.1 nmol/L, and vary on a diel basis. At these concentrations, sulfide may affect the cycling of several trace metals via the formation of stable complexes. Production of sulfide in oxygenated seawater may occur through the hydrolysis of carbonyl sulfide or by sulfate reduction within macroscopic particles in the water column. Removal mechanisms can include oxidation, complexation with particulate trace metals, and metal sulfide precipitation. However, the temporal and spatial distributions suggest a complex set of processes governing the behavior of sulfide in the surface <span class="hlt">ocean</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-as4-01-580.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-as4-01-580.html"><span>Brazil, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, Africa & Antarctica seen from Apollo 4</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>1967-11-09</p> <p>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, <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920006296','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920006296"><span>GLOBEC (Global <span class="hlt">Ocean</span> Ecosystems Dynamics: Northwest <span class="hlt">Atlantic</span> program</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1991-01-01</p> <p>The specific objective of the meeting was to plan an experiment in the Northwestern <span class="hlt">Atlantic</span> to study the marine ecosystem and its role, together with that of climate and physical dynamics, in determining fisheries recruitment. The underlying focus of the GLOBEC initiative is to understand the marine ecosystem as it related to marine living resources and to understand how fluctuation in these resources are driven by climate change and exploitation. In this sense the goal is a solid scientific program to provide basic information concerning major fisheries stocks and the environment that sustains them. The plan is to attempt to reach this understanding through a multidisciplinary program that brings to bear new techniques as disparate as numerical fluid dynamic models of <span class="hlt">ocean</span> circulation, molecular biology and modern acoustic imaging. The effort will also make use of the massive historical data sets on fisheries and the state of the climate in a coordinated manner.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26336038','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26336038"><span>Macroecological patterns of archaeal ammonia oxidizers in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sintes, Eva; De Corte, Daniele; Ouillon, Natascha; Herndl, Gerhard J</p> <p>2015-10-01</p> <p>Macroecological patterns are found in animals and plants, but also in micro-organisms. Macroecological and biogeographic distribution patterns in marine Archaea, however, have not been studied yet. Ammonia-oxidizing Archaea (AOA) show a bipolar distribution (i.e. similar communities in the northernmost and the southernmost locations, separated by distinct communities in the tropical and gyral regions) throughout the <span class="hlt">Atlantic</span>, detectable from epipelagic to upper bathypelagic layers (<2000 m depth). This tentatively suggests an influence of the epipelagic conditions of organic matter production on bathypelagic AOA communities. The AOA communities below 2000 m depth showed a less pronounced biogeographic distribution pattern than the upper 2000 m water column. Overall, AOA in the surface and deep <span class="hlt">Atlantic</span> waters exhibit distance-decay relationships and follow the Rapoport rule in a similar way as bacterial communities and macroorganisms. This indicates a major role of environmental conditions in shaping the community composition and assembly (species sorting) and no, or only weak limits for dispersal in the <span class="hlt">oceanic</span> thaumarchaeal communities. However, there is indication of a different strength of these relationships between AOA and Bacteria, linked to the intrinsic differences between these two domains. © 2015 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.V41C2192W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.V41C2192W"><span>Melt anomalies of the northern <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> basin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, T.; Lin, J.; Tucholke, B. E.</p> <p>2009-12-01</p> <p>We investigated the melt anomalies and lithosphere dynamics of the northern <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> between 76°N and 8°S through combined analysis of seafloor bathymetry, shipboard and satellite-derived gravity, and sediment thickness. Residual mantle Bouguer anomaly (RMBA) was calculated by removing from free-air gravity anomaly the predicted attractions of water-sediment, sediment-crust, and crust-mantle interfaces as well as the effect of lithospheric plate cooling. Residual bathymetry anomaly (RBA) was obtained by subtracting from observed seafloor topography the predicted effects of plate cooling and the observed sediment load. Our analysis indicates that more than 50% of the seafloor has been affected by melt anomalies. The most prominent features that we observe include: (1) A pronounced negative RMBA associated with the Iceland hotspot, the Reykjanes Ridge, and the Mid-<span class="hlt">Atlantic</span> Ridge (MAR) north of Iceland. The region of enhanced magma supply extends southward to the Charlie Gibbs F.Z., northward to the Jan Mayen F.Z., and to both the eastern and western basin margins. The strong negative RMBA associated with the submarine part of the Iceland hotspot reaches -450 mGal, corresponding to modeled crustal thickness of more than 22 km. (2) A widespread effect of the Azores hotspot on crustal accretion at the MAR since 40-50 Ma, as reflected in negative RMBA and positive RBA that extend southward to at least 26.5°N and northward to 44°N. The strongest RMBA anomaly associated with the Azores melt anomaly reaches about -230 mGal, corresponding to crustal thickening about half of that in Iceland. (3) A ~ 500 km wide corridor of negative RMBA is found along the west African margin between 40°N and 6°S, indicating that this region was influenced extensively by melt anomalies associated with the Horseshoe Seamounts, Madeira Islands, Canary Islands, and Cape Verde Islands. Negative RMBA of -100 to -180 mGal is also associated with the Bermuda Rise in the western <span class="hlt">Atlantic</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PrOce.155...54W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PrOce.155...54W"><span>Variations in freshwater pathways from the Arctic <span class="hlt">Ocean</span> into the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Zeliang; Hamilton, James; Su, Jie</p> <p>2017-06-01</p> <p>Understanding the mechanisms that drive exchanges between the Arctic <span class="hlt">Ocean</span> and adjacent <span class="hlt">oceans</span> is critical to building our knowledge of how the Arctic is reacting to a warming climate, and how potential changes in Arctic <span class="hlt">Ocean</span> freshwater export may impact the AMOC (<span class="hlt">Atlantic</span> Meridional Overturning Circulation). Here, freshwater pathways from the Arctic <span class="hlt">Ocean</span> to the North <span class="hlt">Atlantic</span> are investigated using a 1 degree global model. An EOF analysis of modeled sea surface height (SSH) demonstrates that while the second mode accounts for only 15% of the variability, the associated geostrophic currents are strongly correlated with freshwater exports through CAA (Canadian Arctic Archipelago; r = 0.75), Nares Strait (r = 0.77) and Fram Strait (r = -0.60). Separation of sea level into contributing parts allows us to show that the EOF1 is primarily a barotropic mode reflecting variability in bottom pressure equivalent sea level, while the EOF2 mode reflects changes in steric height in the Arctic Basin. This second mode is linked to momentum wind driven surface current, and dominates the Arctic <span class="hlt">Ocean</span> freshwater exports. Both the Arctic Oscillation and Arctic Dipole atmospheric indices are shown to be linked to Arctic <span class="hlt">Ocean</span> freshwater exports, with the forcing associated with the Arctic Dipole reflecting the out-of-phase relationship between transports through the CAA and those through Fram Strait. Finally, observed freshwater transport variation through the CAA is found to be strongly correlated with tide gauge data from the Beaufort Sea coast (r = 0.81), and with the EOF2 mode of GRACE bottom pressure data (r = 0.85) on inter-annual timescales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18211270','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18211270"><span>Abundant proteorhodopsin genes in the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Campbell, Barbara J; Waidner, Lisa A; Cottrell, Matthew T; Kirchman, David L</p> <p>2008-01-01</p> <p>Proteorhodopsin (PR) is a light-driven proton pump that has been found in a variety of marine bacteria, including Pelagibacter ubique, a member of the ubiquitous SAR11 clade. The goals of this study were to explore the diversity of PR genes and to estimate their abundance in the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> using quantitative polymerase chain reaction (QPCR). We found that PR genes in the western portion of the Sargasso Sea could be grouped into 27 clusters, but five clades had the most sequences. Sets of specific QPCR primers were designed to examine the abundance of PR genes in the following four of the five clades: SAR11 (P. ubique and other SAR11 Alphaproteobacteria), BACRED17H8 (Alphaproteobacteria), HOT2C01 (Alphaproteobacteria) and an uncultured subgroup of the Flavobacteria. Two groups (SAR11 and HOT2C01) dominated PR gene abundance in oligotrophic waters, but were significantly less abundant in nutrient- and chlorophyll-rich waters. The other two groups (BACRED17H8 and Flavobacteria subgroup NASB) were less abundant in all waters. Together, these four PR gene types were found in 50% of all bacteria in the Sargasso Sea. We found a significant negative correlation between total PR gene abundance and nutrients and chlorophyll but no significant correlation with light intensity for three of the four PR types in the depth profiles north of the Sargasso Sea. Our data suggest that PR is common in the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>, especially in SAR11 bacteria and another marine alphaproteobacterial group (HOT2C01), and that these PR-bearing bacteria are most abundant in oligotrophic waters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22026605','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22026605"><span>Chondrichthyan egg cases from the south-west <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mabragaña, E; Figueroa, D E; Scenna, L B; Díaz de Astarloa, J M; Colonello, J H; Delpiani, G</p> <p>2011-11-01</p> <p>Egg cases of 21 oviparous chondrichthyan species from the south-west <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> are described and compared. The catshark Schroederichthys bivius has a cigar-shaped egg case with curled tendrils only at the posterior end. Egg cases of the elephant fish Callorhinchus callorynchus are spindle-shaped with anterior and posterior tubular extensions and lateral flanges. The skate Amblyraja doellojuradoi presents medium-sized egg cases (71 mm in length) with a lateral keel extending to the first portion of the horns. The endemic skate species of the genus Atlantoraja have medium to large egg cases (69-104 mm in length) and present relatively large posterior horns. Egg cases of the genus Bathyraja have a medium size, 75-98 mm in length, and are characterized by a very similar morphology, a relatively smooth to rough surface case and posterior horns strongly curved inwards. Egg cases of the genera Dipturus and Zearaja are very large, 115-230 mm in length, and have a well-developed posterior apron. Despite the problematical identification of skates at species level, the egg capsules of the endemic genus Psammobatis are easily diagnosed; the capsules are small (25-53 mm in length), those of Psammobatis rutrum being the smallest known to date in the world. Egg cases of Rioraja agassizi have a medium size, 61-68 mm in length, relatively straight sides, a smooth surface and silky attachment fibres placed in the lateral keel next to each horn. Those of the genus Sympterygia are small to medium sized, 51-86 mm in length, and display the thickest lateral keel and the longest posterior horns among the skates of the world. Egg cases can be a useful tool for identifying species and egg-laying areas; therefore, a provisional key for the south-west <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> chondrichthyan capsules is presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ERL....12d4024P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ERL....12d4024P"><span>Attribution of the 2015 record high sea surface temperatures over the central <span class="hlt">equatorial</span> Pacific and tropical Indian <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Park, In-Hong; Min, Seung-Ki; Yeh, Sang-Wook; Weller, Evan; Kim, Seon Tae</p> <p>2017-04-01</p> <p>This study assessed the anthropogenic contribution to the 2015 record-breaking high sea surface temperatures (SSTs) observed in the central <span class="hlt">equatorial</span> Pacific and tropical Indian <span class="hlt">Ocean</span>. Considering a close link between extreme warm events in these regions, we conducted a joint attribution analysis using a fraction of attributable risk approach. Probability of occurrence of such extreme anomalies and long-term trends for the two <span class="hlt">oceanic</span> regions were compared between CMIP5 multi-model simulations with and without anthropogenic forcing. Results show that the excessive warming in both regions is well beyond the range of natural variability and robustly attributable to human activities due to greenhouse gas increase. We further explored associated mechanisms including the Bjerknes feedback and background anthropogenic warming. It is concluded that background warming was the main contribution to the 2015 extreme SST event over the central <span class="hlt">equatorial</span> Pacific <span class="hlt">Ocean</span> on a developing El Niño condition, which in turn induced the extreme SST event over the tropical Indian <span class="hlt">Ocean</span> through the atmospheric bridge effect.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4069082','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4069082"><span>Comparison of Deep-Water Viromes from the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> and the Mediterranean Sea</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Winter, Christian; Garcia, Juan A. L.; Weinbauer, Markus G.; DuBow, Michael S.; Herndl, Gerhard J.</p> <p>2014-01-01</p> <p>The aim of this study was to compare the composition of two deep-sea viral communities obtained from the Romanche Fracture Zone in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> (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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> 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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> and for 83.6% in the Mediterranean Sea. Despite characteristic differences in hydrographic features between the sampling sites in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> and the Mediterranean Sea, 440 virus genomes were found in both viromes. An additional 431 virus genomes were identified in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> and 75 virus genomes were only found in the Mediterranean Sea. The results indicate that the rather contrasting deep-sea environments of the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> and the Mediterranean Sea share a common core set of virus types constituting the majority of both virus communities in terms of relative abundance (<span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>: 81.4%; Mediterranean Sea: 88.7%). PMID:24959907</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24959907','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24959907"><span>Comparison of deep-water viromes from the <span class="hlt">atlantic</span> <span class="hlt">ocean</span> and the mediterranean sea.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Winter, Christian; Garcia, Juan A L; Weinbauer, Markus G; DuBow, Michael S; Herndl, Gerhard J</p> <p>2014-01-01</p> <p>The aim of this study was to compare the composition of two deep-sea viral communities obtained from the Romanche Fracture Zone in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> (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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> 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 <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> and for 83.6% in the Mediterranean Sea. Despite characteristic differences in hydrographic features between the sampling sites in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> and the Mediterranean Sea, 440 virus genomes were found in both viromes. An additional 431 virus genomes were identified in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> and 75 virus genomes were only found in the Mediterranean Sea. The results indicate that the rather contrasting deep-sea environments of the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> and the Mediterranean Sea share a common core set of virus types constituting the majority of both virus communities in terms of relative abundance (<span class="hlt">Atlantic</span> <span class="hlt">Ocean</span>: 81.4%; Mediterranean Sea: 88.7%).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSPO44A3120B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSPO44A3120B"><span>Tracing the Sinking of Dense <span class="hlt">Ocean</span> Waters in the North <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brueggemann, N.; Katsman, C. A.; Dijkstra, H.</p> <p>2016-02-01</p> <p>In this study, we investigate the sinking of dense water masses in the North <span class="hlt">Atlantic</span>. Therefore, we use data from an eddy permitting (0.1o) <span class="hlt">ocean</span> model of the Parallel <span class="hlt">Ocean</span> Program (POP). Velocity fields of the model are used to advect Lagrangian floats with the Connectivity Modelling System (CMS). Model and float data are used to identify regions where water masses sink into the deep <span class="hlt">ocean</span>. Theoretical considerations predict that water masses can only sink if the geostrophic balance is broken. We identify mechanisms that are responsible for the ageostrophic dynamics and compare our findings with frequently discussed theories. Since eddies seem to play a dominant role for the deep water sinking, it is questionable to which extent coarser resolved <span class="hlt">ocean</span> models that do not resolve the eddies are able to capture the deep water sinking. Especially, we aim to clarify if the sinking in a coarser resolved counterpart of the POP <span class="hlt">ocean</span> model (1o) is due to different mechanisms compared to its eddy permitting (0.1o) counterpart. By this, we aim at understanding how the deep sinking of water masses as one part of the Meridional Overturning Circulation is represented in typically coarser resolved climate models and how realistic these processes are represented in comparison to higher resolved <span class="hlt">ocean</span> models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26982180','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26982180"><span>Phytoplankton across Tropical and Subtropical Regions of the <span class="hlt">Atlantic</span>, Indian and Pacific <span class="hlt">Oceans</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Estrada, Marta; Delgado, Maximino; Blasco, Dolors; Latasa, Mikel; Cabello, Ana María; Benítez-Barrios, Verónica; Fraile-Nuez, Eugenio; Mozetič, Patricija; Vidal, Montserrat</p> <p>2016-01-01</p> <p>We examine the large-scale distribution patterns of the nano- and microphytoplankton collected from 145 <span class="hlt">oceanic</span> stations, at 3 m depth, the 20% light level and the depth of the subsurface chlorophyll maximum, during the Malaspina-2010 Expedition (December 2010-July 2011), which covered 15 biogeographical provinces across the <span class="hlt">Atlantic</span>, Indian and Pacific <span class="hlt">oceans</span>, between 35°N and 40°S. In general, the water column was stratified, the surface layers were nutrient-poor and the nano- and microplankton (hereafter phytoplankton, for simplicity, although it included also heterotrophic protists) community was dominated by dinoflagellates, other flagellates and coccolithophores, while the contribution of diatoms was only important in zones with shallow nutriclines such as the <span class="hlt">equatorial</span> upwelling regions. We applied a principal component analysis to the correlation matrix among the abundances (after logarithmic transform) of the 76 most frequent taxa to synthesize the information contained in the phytoplankton data set. The main trends of variability identified consisted of: 1) A contrast between the community composition of the upper and the lower parts of the euphotic zone, expressed respectively by positive or negative scores of the first principal component, which was positively correlated with taxa such as the dinoflagellates Oxytoxum minutum and Scrippsiella spp., and the coccolithophores Discosphaera tubifera and Syracosphaera pulchra (HOL and HET), and negatively correlated with taxa like Ophiaster hydroideus (coccolithophore) and several diatoms, 2) a general abundance gradient between phytoplankton-rich regions with high abundances of dinoflagellate, coccolithophore and ciliate taxa, and phytoplankton-poor regions (second principal component), 3) differences in dominant phytoplankton and ciliate taxa among the <span class="hlt">Atlantic</span>, the Indian and the Pacific <span class="hlt">oceans</span> (third principal component) and 4) the occurrence of a diatom-dominated assemblage (the fourth principal</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4794153','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4794153"><span>Phytoplankton across Tropical and Subtropical Regions of the <span class="hlt">Atlantic</span>, Indian and Pacific <span class="hlt">Oceans</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Estrada, Marta; Delgado, Maximino; Blasco, Dolors; Latasa, Mikel; Cabello, Ana María; Benítez-Barrios, Verónica; Fraile-Nuez, Eugenio; Mozetič, Patricija; Vidal, Montserrat</p> <p>2016-01-01</p> <p>We examine the large-scale distribution patterns of the nano- and microphytoplankton collected from 145 <span class="hlt">oceanic</span> stations, at 3 m depth, the 20% light level and the depth of the subsurface chlorophyll maximum, during the Malaspina-2010 Expedition (December 2010-July 2011), which covered 15 biogeographical provinces across the <span class="hlt">Atlantic</span>, Indian and Pacific <span class="hlt">oceans</span>, between 35°N and 40°S. In general, the water column was stratified, the surface layers were nutrient-poor and the nano- and microplankton (hereafter phytoplankton, for simplicity, although it included also heterotrophic protists) community was dominated by dinoflagellates, other flagellates and coccolithophores, while the contribution of diatoms was only important in zones with shallow nutriclines such as the <span class="hlt">equatorial</span> upwelling regions. We applied a principal component analysis to the correlation matrix among the abundances (after logarithmic transform) of the 76 most frequent taxa to synthesize the information contained in the phytoplankton data set. The main trends of variability identified consisted of: 1) A contrast between the community composition of the upper and the lower parts of the euphotic zone, expressed respectively by positive or negative scores of the first principal component, which was positively correlated with taxa such as the dinoflagellates Oxytoxum minutum and Scrippsiella spp., and the coccolithophores Discosphaera tubifera and Syracosphaera pulchra (HOL and HET), and negatively correlated with taxa like Ophiaster hydroideus (coccolithophore) and several diatoms, 2) a general abundance gradient between phytoplankton-rich regions with high abundances of dinoflagellate, coccolithophore and ciliate taxa, and phytoplankton-poor regions (second principal component), 3) differences in dominant phytoplankton and ciliate taxa among the <span class="hlt">Atlantic</span>, the Indian and the Pacific <span class="hlt">oceans</span> (third principal component) and 4) the occurrence of a diatom-dominated assemblage (the fourth principal</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002GeCoA..66.1943S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002GeCoA..66.1943S"><span>Temporal and spatial variability of cobalt in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saito, Mak A.; Moffett, James W.</p> <p>2002-06-01</p> <p>The spatial and temporal variability of cobalt in the <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> was investigated by means of adsorptive cathodic stripping voltammetry. A vertical profile of total dissolved cobalt at the Bermuda <span class="hlt">Atlantic</span> Time Series station ranged from 17 to 73 pM and displayed surface depletion indicative of biological utilization. This profile when compared with a cobalt profile from the northeast Pacific shows no increase in deep-water concentrations with thermohaline circulation through the deep <span class="hlt">ocean</span> basins. Moreover, the middepth maximum observed in northeast Pacific profiles is not present in the Sargasso Sea, perhaps because of the lack of cobalt scavenging by particulate manganese oxides in surface waters and to the absence of a suboxic oxygen minimum zone, which, if present, could dissolve the manganese oxides. Total dissolved cobalt measurements were also made on a surface transect from the Sargasso Sea to coastal Massachusetts, USA, and on time-series samples from the Moored In Situ Trace Element Serial Sampler. Dissolved cobalt on this transect correlated strongly with salinity (r2 = 0.93) and ranged from 19 to 133 pM, indicating mixing of cobalt from shelf waters into the Sargasso Sea. Time-series samples near Bermuda did not show an obvious response to the summer maximum in aeolian dust deposition, with an annual average of 20 ± 10 pM at 40- to 47-m depths. By use of this annual value and particulate cobalt data from the literature, 100-m surface-water residence times were calculated to be as low as 0.32 yr for cobalt. Several sharp decreases in cobalt were observed in the time series that occurred simultaneously with a shallowing of the thermocline depth. These decreases could be caused by nutrient drawdown associated with higher productivity mesoscale eddy events. A west-east surface transect across the South <span class="hlt">Atlantic</span> showed high cobalt concentrations at the boundaries of the transect and low concentrations in the center despite the high precipitation rates</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ClDy...47.1127M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ClDy...47.1127M"><span>Seasonal influence of the sea surface temperature on the low atmospheric circulation and precipitation in the eastern <span class="hlt">equatorial</span> <span class="hlt">Atlantic</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meynadier, Rémi; de Coëtlogon, Gaëlle; Leduc-Leballeur, Marion; Eymard, Laurence; Janicot, Serge</p> <p>2016-08-01</p> <p>The air-sea interaction in the Gulf of Guinea and its role in setting precipitation at the Guinean coast is investigated in the present paper. This study is based on satellite observations and WRF simulations forced by different sea surface temperature (SST) patterns. It shows that the seasonal cold tongue setup in the Gulf of Guinea, along with its very active northern front, tends to strongly constrain the low level atmospheric dynamics between the equator and the Guinean coast. Underlying mechanisms including local SST effect on the marine boundary layer stability and hydrostatically-changed meridional pressure gradient through changes in SST gradient are quantified in WRF regarding observations and CFSR reanalyses. Theses mechanisms strongly impact moisture flux convergence near the coast, leading to the installation of the first rainy season of the West African Monsoon (WAM) system. The current study details the mechanisms by which the <span class="hlt">Atlantic</span> <span class="hlt">Equatorial</span> cold tongue plays a major role in the pre-onset of the boreal WAM.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005ClDy...25..497B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005ClDy...25..497B"><span>Formation and pathways of North <span class="hlt">Atlantic</span> Deep Water in a coupled ice-<span class="hlt">ocean</span> model of the Arctic-North <span class="hlt">Atlantic</span> <span class="hlt">Oceans</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bailey, David A.; Rhines, Peter B.; Häkkinen, Sirpa</p> <p>2005-10-01</p> <p>We investigate the formation process and pathways of deep water masses in a coupled ice-<span class="hlt">ocean</span> model of the Arctic and North <span class="hlt">Atlantic</span> <span class="hlt">Oceans</span>. The intent is to determine the relative roles of these water masses from the different source regions (Arctic <span class="hlt">Ocean</span>, Nordic Seas, and Subpolar <span class="hlt">Atlantic</span>) in the meridional overturning circulation. The model exhibits significant decadal variability in the deep western boundary current and the overturning circulation. We use detailed diagnostics to understand the process of water mass formation in the model and the resulting effects on the North <span class="hlt">Atlantic</span> overturning circulation. Particular emphasis is given to the multiple sources of North <span class="hlt">Atlantic</span> Deep Water, the dominant deep water masses of the world <span class="hlt">ocean</span>. The correct balance of Labrador Sea, Greenland Sea and Norwegian Sea sources is difficult to achieve in climate models, owing to small-scale sinking and convection processes. The global overturning circulation is described as a function of potential temperature and salinity, which more clearly signifies dynamical processes and clarifies resolution problems inherent to the high latitude <span class="hlt">oceans</span>. We find that fluxes of deep water masses through various passages in the model are higher than observed estimates. Despite the excessive volume flux, the Nordic Seas overflow waters are diluted by strong mixing and enter the Labrador Sea at a lighter density. Through strong subpolar convection, these waters along with other North <span class="hlt">Atlantic</span> water masses are converted into the densest waters [similar density to Antarctic Bottom Water (AABW)] in the North <span class="hlt">Atlantic</span>. We describe the diminished role of salinity in the Labrador Sea, where a shortage of buoyant surface water (or excess of high salinity water) leads to overly strong convection. The result is that the <span class="hlt">Atlantic</span> overturning circulation in the model is very sensitive to the surface heat flux in the Labrador Sea and hence is correlated with the North <span class="hlt">Atlantic</span> Oscillation. As strong</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ClDy..tmp..254K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ClDy..tmp..254K"><span>Tropical climate variability: interactions across the Pacific, Indian, and <span class="hlt">Atlantic</span> <span class="hlt">Oceans</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kajtar, Jules B.; Santoso, Agus; England, Matthew H.; Cai, Wenju</p> <p>2016-06-01</p> <p>Complex interactions manifest between modes of tropical climate variability across the Pacific, Indian, and <span class="hlt">Atlantic</span> <span class="hlt">Oceans</span>. For example, the El Niño-Southern Oscillation (ENSO) extends its influence on modes of variability in the tropical Indian and <span class="hlt">Atlantic</span> <span class="hlt">Oceans</span>, which in turn feed back onto ENSO. Interactions between pairs of modes can alter their strength, periodicity, seasonality, and ultimately their predictability, yet little is known about the role that a third mode plays. Here we examine the interactions and relative influences between pairs of climate modes using ensembles of 100-year partially coupled experiments in an otherwise fully coupled general circulation model. In these experiments, the air-sea interaction over each tropical <span class="hlt">ocean</span> basin, as well as pairs of <span class="hlt">ocean</span> basins, is suppressed in turn. We find that Indian <span class="hlt">Ocean</span> variability has a net damping effect on ENSO and <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> variability, and conversely they each promote Indian <span class="hlt">Ocean</span> variability. The connection between the Pacific and the <span class="hlt">Atlantic</span> is most clearly revealed in the absence of Indian <span class="hlt">Ocean</span> variability. Our model runs suggest a weak damping influence by <span class="hlt">Atlantic</span> variability on ENSO, and an enhancing influence by ENSO on <span class="hlt">Atlantic</span> variability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ClDy...48.2173K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ClDy...48.2173K"><span>Tropical climate variability: interactions across the Pacific, Indian, and <span class="hlt">Atlantic</span> <span class="hlt">Oceans</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kajtar, Jules B.; Santoso, Agus; England, Matthew H.; Cai, Wenju</p> <p>2017-04-01</p> <p>Complex interactions manifest between modes of tropical climate variability across the Pacific, Indian, and <span class="hlt">Atlantic</span> <span class="hlt">Oceans</span>. For example, the El Niño-Southern Oscillation (ENSO) extends its influence on modes of variability in the tropical Indian and <span class="hlt">Atlantic</span> <span class="hlt">Oceans</span>, which in turn feed back onto ENSO. Interactions between pairs of modes can alter their strength, periodicity, seasonality, and ultimately their predictability, yet little is known about the role that a third mode plays. Here we examine the interactions and relative influences between pairs of climate modes using ensembles of 100-year partially coupled experiments in an otherwise fully coupled general circulation model. In these experiments, the air-sea interaction over each tropical <span class="hlt">ocean</span> basin, as well as pairs of <span class="hlt">ocean</span> basins, is suppressed in turn. We find that Indian <span class="hlt">Ocean</span> variability has a net damping effect on ENSO and <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> variability, and conversely they each promote Indian <span class="hlt">Ocean</span> variability. The connection between the Pacific and the <span class="hlt">Atlantic</span> is most clearly revealed in the absence of Indian <span class="hlt">Ocean</span> variability. Our model runs suggest a weak damping influence by <span class="hlt">Atlantic</span> variability on ENSO, and an enhancing influence by ENSO on <span class="hlt">Atlantic</span> variability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009ClDy...32..753L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009ClDy...32..753L"><span>An intimate coupling of <span class="hlt">ocean</span>-atmospheric interaction over the extratropical North <span class="hlt">Atlantic</span> and Pacific</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Chun; Wu, Lixin; Wang, Qi; Qu, Liwei; Zhang, Liping</p> <p>2009-05-01</p> <p>The inter-basin teleconnection between the North <span class="hlt">Atlantic</span> and the North Pacific <span class="hlt">ocean</span>-atmosphere interaction is studied using a coupled <span class="hlt">ocean</span>-atmosphere general circulation model. In the model, an idealized <span class="hlt">oceanic</span> temperature anomaly is initiated over the Kuroshio and the Gulf Stream extension region to track the coupled evolution of <span class="hlt">ocean</span> and atmosphere interaction, respectively. The experiments explicitly demonstrate that both the North Pacific and the North <span class="hlt">Atlantic</span> <span class="hlt">ocean</span>-atmosphere interactions are intimately coupled through an inter-basin atmospheric teleconnection. This fast inter-basin communication can transmit <span class="hlt">oceanic</span> variability between the North <span class="hlt">Atlantic</span> and the North Pacific through local <span class="hlt">ocean</span>-to-atmosphere feedbacks. The leading mode of the extratropical atmospheric internal variability plays a dominant role in shaping the hemispheric-scale response forced by <span class="hlt">oceanic</span> variability over the North <span class="hlt">Atlantic</span> and Pacific. Modeling results also suggest that a century (two centuries) long observations are necessary for the detection of Pacific response to <span class="hlt">Atlantic</span> forcings (<span class="hlt">Atlantic</span> response to Pacific forcing).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002EGSGA..27.3633B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002EGSGA..27.3633B"><span>The Carbon Isotopic Record of The C37:2 Alkenone In Sediments From The <span class="hlt">Equatorial</span> and South <span class="hlt">Atlantic</span>: Last Glacial Maximum (lgm) Vs. Holocene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Benthien, A.; Schulte, S.; Andersen, N.; Müller, P. J.; Schneider, R. R.</p> <p></p> <p>The carbon isotopic signal of the C37-alkenone, a taxon-specific biomarker for hap- tophyte algae, has been used in various paleoceanographic studies as a proxy for an- cient surface water CO2 concentration ([CO2aq]). However, a number of recent cul- ture, field and sediment studies imply that the carbon isotopic fractionation (ep) of alkenones is controlled predominantly by physiological processes and environmental factors other than the ambient CO2 concentration (i.e., growth rate, nutrient availabil- ity, light intensity, active carbon uptake, bicarbonate utilisation). The environmental conditions controlling phytoplankton growth are likely to vary strongly with oceano- graphic setting. Culture experiments can not perfectly recreate natural growth con- ditions and physical processes which affect the carbon isotopic signal in the field and its preservation in the sediment. Consequently, the use of the carbon isotopic record of alkenones as a reliable paleoceonographic proxy also requires sediment- based studies covering a broad range of different <span class="hlt">oceanic</span> regimes for the past and modern <span class="hlt">ocean</span>. Here, we present the first basin-wide comparison of alkenone ep val- ues from sediments of the Last Glacial Maximum (LGM) and the latest Holocene. Different oceanographic regions from the <span class="hlt">equatorial</span> and South <span class="hlt">Atlantic</span> <span class="hlt">Ocean</span> were examined. Generally, alkenone ep is lower during the LGM compared to the Holocene. Considering present understanding of LGM-Holocene changes in surface water condi- tions, the observed glacial/interglacial difference in ep indicates that different effects controlled the isotopic fractionation in alkenone-producing algae depending on the regional setting. In upwelling regions, the variations in ep probably reflect a glacial increase in haptophyte productivity controlled by the availability of surface water nu- trient concentrations. By contrast, in oligotrophic areas slightly lower nutrient content was available during LGM. Here, the observed ep</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMPP43B1477P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMPP43B1477P"><span>Deep <span class="hlt">Ocean</span> Circulation and Nutrient Contents from <span class="hlt">Atlantic</span>-Pacific Gradients of Neodymium and Carbon Isotopes During the Last 1 Ma</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Piotrowski, A. M.; Elderfield, H.; Howe, J. N. W.</p> <p>2014-12-01</p> <p>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 cy