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Sample records for atlantic period ca

  1. North Atlantic Globorotalia inflata coretop Mg/Ca calibrations and temperature reconstructions over Termination I

    International Nuclear Information System (INIS)

    Mg/Ca ratios from planktonic foraminifera are widely used as an independent proxy for ocean temperature. The choice of calibration is vital for reconstructing meaningful temperatures. We present preliminary results based on a new Mg/Ca-temperature calibration (Mg/Ca = 0.92e0.039T) for the thermocline-dwelling foraminifera Globorotalia inflata, derived using a suite of North Atlantic coretops. The downcore Mg/Ca record from core SU90-03 (400N, 320W) was used to compare how our new and existing calibrations performed for the Holocene and over the large scale change associated with Termination I.

  2. North Atlantic Globorotalia inflata coretop Mg/Ca calibrations and temperature reconstructions over Termination I

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, Elizabeth J; Chapman, Mark R; Andrews, Julian E, E-mail: e.farmer@uea.ac.u [University of East Anglia, School of Environmental Sciences, Norwich, NR4 7TJ (United Kingdom)

    2010-03-15

    Mg/Ca ratios from planktonic foraminifera are widely used as an independent proxy for ocean temperature. The choice of calibration is vital for reconstructing meaningful temperatures. We present preliminary results based on a new Mg/Ca-temperature calibration (Mg/Ca = 0.92e{sup 0.039T}) for the thermocline-dwelling foraminifera Globorotalia inflata, derived using a suite of North Atlantic coretops. The downcore Mg/Ca record from core SU90-03 (40{sup 0}N, 32{sup 0}W) was used to compare how our new and existing calibrations performed for the Holocene and over the large scale change associated with Termination I.

  3. Evidence for cooler European summers during periods of changing meltwater flux to the North Atlantic.

    Science.gov (United States)

    Heiri, Oliver; Tinner, Willy; Lotter, André F

    2004-10-26

    We analyzed fossil chironomids (nonbiting midges) and pollen in two lake-sediment records to reconstruct and quantify Holocene summer-temperature fluctuations in the European Alps. Chironomid and pollen records indicate five centennial-scale cooling episodes during the early- and mid-Holocene. The strongest temperature declines of approximately 1 degrees C are inferred at approximately 10,700-10,500 and 8,200-7,600 calibrated 14C years B.P., whereas other temperature fluctuations are of smaller amplitude. Two forcing mechanisms have been presented recently to explain centennial-scale climate variability in Europe during the early- and mid-Holocene, both involving changes in Atlantic thermohaline circulation. In the first mechanism, changes in meltwater flux from the North American continent to the North Atlantic are responsible for changes in the Atlantic thermohaline circulation, thereby affecting circum-Atlantic climate. In the second mechanism, solar variability is the cause of Holocene climatic fluctuations, possibly triggering changes in Atlantic thermohaline overturning. Within their dating uncertainty, the two major cooling periods in the European Alps are coeval with substantial changes in the routing of North American freshwater runoff to the North Atlantic, whereas quantitatively, our climatic reconstructions show a poor agreement with available records of past solar activity. Thus, our results suggest that, during the early- and mid-Holocene, freshwater-induced Atlantic circulation changes had stronger influence on Alpine summer temperatures than solar variability and that Holocene thermohaline circulation reductions have led to summer-temperature declines of up to 1 degrees C in central Europe. PMID:15492214

  4. The key role of topography in altering North Atlantic atmospheric circulation during the last glacial period

    Directory of Open Access Journals (Sweden)

    F. S. R. Pausata

    2011-10-01

    Full Text Available The Last Glacial Maximum (LGM; 21 000 yr before present was a period of low atmospheric greenhouse gas concentrations, when vast ice sheets covered large parts of North America and Europe. Paleoclimate reconstructions and modeling studies suggest that the atmospheric circulation was substantially altered compared to today, both in terms of its mean state and its variability. Here we present a suite of coupled model simulations designed to investigate both the separate and combined influences of the main LGM boundary condition changes (greenhouse gases, ice sheet topography and ice sheet albedo on the mean state and variability of the atmospheric circulation as represented by sea level pressure (SLP and 200-hPa zonal wind in the North Atlantic sector. We find that ice sheet topography accounts for most of the simulated changes during the LGM. Greenhouse gases and ice sheet albedo affect the SLP gradient in the North Atlantic, but the overall placement of high and low pressure centers is controlled by topography. Additional analysis shows that North Atlantic sea surface temperatures and sea ice edge position do not substantially influence the pattern of the climatological-mean SLP field, SLP variability or the position of the North Atlantic jet in the LGM.

  5. South Atlantic intermediate water advances into the North-east Atlantic with reduced Atlantic meridional overturning circulation during the last glacial period

    Science.gov (United States)

    Dubois-Dauphin, Quentin; Bonneau, Lucile; Colin, Christophe; Montero-Serrano, Jean-Carlos; Montagna, Paolo; Blamart, Dominique; Hebbeln, Dierk; Van Rooij, David; Pons-Branchu, Edwige; Hemsing, Freya; Wefing, Anne-Marie; Frank, Norbert

    2016-06-01

    The Nd isotopic composition (ɛNd) of seawater and cold-water coral (CWC) samples from the Gulf of Cádiz and the Alboran Sea, at a depth of 280-827 m were investigated in order to constrain middepth water mass dynamics within the Gulf of Cádiz over the past 40 ka. ɛNd of glacial and Holocene CWC from the Alboran Sea and the northern Gulf of Cádiz reveals relatively constant values (-8.6 to -9.0 and -9.5 to -10.4, respectively). Such values are similar to those of the surrounding present-day middepth waters from the Mediterranean Outflow Water (MOW; ɛNd ˜ -9.4) and Mediterranean Sea Water (MSW; ɛNd ˜ -9.9). In contrast, glacial ɛNd values for CWC collected at thermocline depth (550-827 m) in the southern Gulf of Cádiz display a higher average value (-8.9 ± 0.4) compared to the present-day value (-11.7 ± 0.3). This implies a higher relative contribution of water masses of Mediterranean (MSW) or South Atlantic origin (East Antarctic Intermediate Water, EAAIW). Our study has produced the first evidence of significant radiogenic ɛNd values (˜ -8) at 19, 23-24, and 27 ka, which are coeval with increasing iceberg discharges and a weakening of Atlantic Meridional Overturning Circulation (AMOC). Since MOW ɛNd values remained stable during the last glacial period, it is suggested that these radiogenic ɛNd values most likely reflect an enhanced northward propagation of glacial EAAIW into the eastern Atlantic Basin.

  6. Orbital and suborbital variability in North Atlantic bottom water temperature obtained from deep-sea ostracod Mg/Ca ratios

    Science.gov (United States)

    Cronin, T. M.; Dwyer, G.S.; Baker, P.A.; Rodriguez-Lazaro, J.; DeMartino, D.M.

    2000-01-01

    Magnesium/calcium (Mg/Ca) ratios were measured in the deep-sea ostracod (Crustacea) genus Krithe from Chain core 82-24-4PC from the western mid-Atlantic Ridge (3427 m) in order to estimate ocean circulation and bottom water temperature (BWT) variability over the past 200,000 years. Mg/Ca ratios have been used as a paleothermometer because the ratios are controlled primarily by ambient water temperatures at the time the organism secretes its adult carapace. Over the past two glacial-interglacial cycles, Mg/Ca values oscillated between about 7 mmol/mol and 12 mmol/mol, equivalent to a BWT range of 0 to > 3.5??C. The lowest values were obtained on specimens from glacial marine isotope stages (MISs) 2, 4 and 6; the highest values were obtained from specimens from the early part of the Holocene interglacial (MIS 1), and also from MISs 5 and 7. These trends suggest that BWTs in the North Atlantic Ocean fluctuate over orbital time scales. Suborbital variability in Mg/Ca ratios and BWT was also observed for the past 100,000 years. Ratios rose from ~8 mmol/mol to ~10 mmol/mol (implying a BWT increase of ~1 to 3??C) during 14 Mg/Ca excursions. The highest ratios were found in Krithe dated at approximately 32, 36-38, 43, 48, 73, 85 and 93 ka. Although the age model for the Chain 82-24-4PC and temporal resolution do not allow precise correlation, some of these deep-sea bottom temperature excursions appear to correspond to Heinrich events recorded in other regions of the North Atlantic and perhaps Dansgaard-Oeschger interstadial events recorded in Greenland ice cores. If confirmed, this would support the hypothesis that millennial-scale oscillations of climate in the North Atlantic are capable of affecting global climate via thermohaline circulation changes. (C) 2000 Elsevier Science B.V.

  7. Rhodolith beds are major CaCO3 bio-factories in the tropical South West Atlantic.

    Science.gov (United States)

    Amado-Filho, Gilberto M; Moura, Rodrigo L; Bastos, Alex C; Salgado, Leonardo T; Sumida, Paulo Y; Guth, Arthur Z; Francini-Filho, Ronaldo B; Pereira-Filho, Guilherme H; Abrantes, Douglas P; Brasileiro, Poliana S; Bahia, Ricardo G; Leal, Rachel N; Kaufman, Les; Kleypas, Joanie A; Farina, Marcos; Thompson, Fabiano L

    2012-01-01

    Rhodoliths are nodules of non-geniculate coralline algae that occur in shallow waters (Rhodolith beds stand with kelp beds, seagrass meadows, and coralline algal reefs as one of the world's four largest macrophyte-dominated benthic communities. Geographic distribution of rhodolith beds is discontinuous, with large concentrations off Japan, Australia and the Gulf of California, as well as in the Mediterranean, North Atlantic, eastern Caribbean and Brazil. Although there are major gaps in terms of seabed habitat mapping, the largest rhodolith beds are purported to occur off Brazil, where these communities are recorded across a wide latitudinal range (2°N-27°S). To quantify their extent, we carried out an inter-reefal seabed habitat survey on the Abrolhos Shelf (16°50'-19°45'S) off eastern Brazil, and confirmed the most expansive and contiguous rhodolith bed in the world, covering about 20,900 km(2). Distribution, extent, composition and structure of this bed were assessed with side scan sonar, remotely operated vehicles, and SCUBA. The mean rate of CaCO(3) production was estimated from in situ growth assays at 1.07 kg m(-2) yr(-1), with a total production rate of 0.025 Gt yr(-1), comparable to those of the world's largest biogenic CaCO(3) deposits. These gigantic rhodolith beds, of areal extent equivalent to the Great Barrier Reef, Australia, are a critical, yet poorly understood component of the tropical South Atlantic Ocean. Based on the relatively high vulnerability of coralline algae to ocean acidification, these beds are likely to experience a profound restructuring in the coming decades.

  8. Rhodolith beds are major CaCO3 bio-factories in the tropical South West Atlantic.

    Directory of Open Access Journals (Sweden)

    Gilberto M Amado-Filho

    Full Text Available Rhodoliths are nodules of non-geniculate coralline algae that occur in shallow waters (<150 m depth subjected to episodic disturbance. Rhodolith beds stand with kelp beds, seagrass meadows, and coralline algal reefs as one of the world's four largest macrophyte-dominated benthic communities. Geographic distribution of rhodolith beds is discontinuous, with large concentrations off Japan, Australia and the Gulf of California, as well as in the Mediterranean, North Atlantic, eastern Caribbean and Brazil. Although there are major gaps in terms of seabed habitat mapping, the largest rhodolith beds are purported to occur off Brazil, where these communities are recorded across a wide latitudinal range (2°N-27°S. To quantify their extent, we carried out an inter-reefal seabed habitat survey on the Abrolhos Shelf (16°50'-19°45'S off eastern Brazil, and confirmed the most expansive and contiguous rhodolith bed in the world, covering about 20,900 km(2. Distribution, extent, composition and structure of this bed were assessed with side scan sonar, remotely operated vehicles, and SCUBA. The mean rate of CaCO(3 production was estimated from in situ growth assays at 1.07 kg m(-2 yr(-1, with a total production rate of 0.025 Gt yr(-1, comparable to those of the world's largest biogenic CaCO(3 deposits. These gigantic rhodolith beds, of areal extent equivalent to the Great Barrier Reef, Australia, are a critical, yet poorly understood component of the tropical South Atlantic Ocean. Based on the relatively high vulnerability of coralline algae to ocean acidification, these beds are likely to experience a profound restructuring in the coming decades.

  9. A comparison of benthic foraminiferal Mn/Ca and sedimentary Mn/Al as proxies of relative bottom water oxygenation in the low latitude NE Atlantic upwelling system

    Directory of Open Access Journals (Sweden)

    C. L. McKay

    2015-05-01

    Full Text Available Trace element incorporation into foraminiferal shells (tests is governed by physical and chemical conditions of the surrounding marine environment and therefore foraminiferal geochemistry provides a means of palaeoceanographic reconstructions. With the availability of high spatial resolution instrumentation with high precision, foraminiferal geochemistry has become a major research topic over recent years. However, reconstructions of past bottom water oxygenation using foraminiferal tests remain in their infancy. In this study we explore the potential of using Mn/Ca determined by Secondary Ion Mass Spectrometry (SIMS as well as by Flow-Through Inductively Coupled Plasma Optical Emission Spectroscopy (FT-ICP-OES in the benthic foraminiferal species Eubuliminella exilis as a proxy for recording changes in bottom water oxygen conditions in the low latitude NE Atlantic upwelling system. Furthermore, we compare the SIMS and FT-ICP-OES results with published Mn/Al in the bulk sediment from the same sediment core. This is the first time that benthic foraminiferal Mn/Ca is directly compared with Mn/Al in the bulk sediment, which largely agree on the former oxygen conditions. Samples were selected to include different productivity regimes related to Marine Isotope Stage 3 (35–28 ka, the Last Glacial Maximum (28–19 ka, Heinrich Event 1 (18–15.5 ka, Bølling Allerød (15.5–13.5 ka and the Younger Dryas (13.5–11.5 ka. Foraminiferal Mn/Ca determined by SIMS and FT-ICP-OES are comparable. Mn/Ca was higher during periods with high primary productivity, such as during the Younger Dryas which indicates low oxygen conditions. This is further supported by the benthic foraminiferal faunal composition. Our results highlight the proxy potential of Mn/Ca in benthic foraminifera from upwelling systems for reconstructing past variations in oxygen conditions of the sea floor environment as well as the need to use it in combination with other proxy records such

  10. On the role of periodic structures in the lower jaw of the atlantic bottlenose dolphin (Tursiops truncatus)

    Energy Technology Data Exchange (ETDEWEB)

    Dible, S A; Flint, J A; Lepper, P A [Electronic and Electrical Engineering, Loughborough University, Loughborough, LE11 3TU (United Kingdom)], E-mail: james.flint@ieee.org

    2009-03-01

    This paper proposes the application of band-gap theory to hearing in the atlantic bottlenose dolphin (Tursiops truncatus). Using the transmission line modelling (TLM) technique and published computed tomography (CT) data of an atlantic bottlenose dolphin (Tursiops truncatus), a series of sound propagation experiments have been carried out. It is shown that the teeth in the lower jaw can be viewed as a periodic array of scattering elements which result in the formation of an acoustic stop band (or band gap) that is angular dependent. It is shown through simple and complex geometry simulations that performance enhancements such as improved gain and isolation between the two receive paths can be achieved. This mechanism has the potential to be exploited in direction-finding sonar.

  11. On the role of periodic structures in the lower jaw of the atlantic bottlenose dolphin (Tursiops truncatus)

    International Nuclear Information System (INIS)

    This paper proposes the application of band-gap theory to hearing in the atlantic bottlenose dolphin (Tursiops truncatus). Using the transmission line modelling (TLM) technique and published computed tomography (CT) data of an atlantic bottlenose dolphin (Tursiops truncatus), a series of sound propagation experiments have been carried out. It is shown that the teeth in the lower jaw can be viewed as a periodic array of scattering elements which result in the formation of an acoustic stop band (or band gap) that is angular dependent. It is shown through simple and complex geometry simulations that performance enhancements such as improved gain and isolation between the two receive paths can be achieved. This mechanism has the potential to be exploited in direction-finding sonar

  12. Physiologic and metagenomic attributes of the rhodoliths forming the largest CaCO3 bed in the South Atlantic Ocean.

    Science.gov (United States)

    Cavalcanti, Giselle S; Gregoracci, Gustavo B; dos Santos, Eidy O; Silveira, Cynthia B; Meirelles, Pedro M; Longo, Leila; Gotoh, Kazuyoshi; Nakamura, Shota; Iida, Tetsuya; Sawabe, Tomoo; Rezende, Carlos E; Francini-Filho, Ronaldo B; Moura, Rodrigo L; Amado-Filho, Gilberto M; Thompson, Fabiano L

    2014-01-01

    Rhodoliths are free-living coralline algae (Rhodophyta, Corallinales) that are ecologically important for the functioning of marine environments. They form extensive beds distributed worldwide, providing a habitat and nursery for benthic organisms and space for fisheries, and are an important source of calcium carbonate. The Abrolhos Bank, off eastern Brazil, harbors the world's largest continuous rhodolith bed (of ∼21,000 km(2)) and has one of the largest marine CaCO3 deposits (producing 25 megatons of CaCO3 per year). Nevertheless, there is a lack of information about the microbial diversity, photosynthetic potential and ecological interactions within the rhodolith holobiont. Herein, we performed an ecophysiologic and metagenomic analysis of the Abrolhos rhodoliths to understand their microbial composition and functional components. Rhodoliths contained a specific microbiome that displayed a significant enrichment in aerobic ammonia-oxidizing betaproteobacteria and dissimilative sulfate-reducing deltaproteobacteria. We also observed a significant contribution of bacterial guilds (that is, photolithoautotrophs, anaerobic heterotrophs, sulfide oxidizers, anoxygenic phototrophs and methanogens) in the rhodolith metagenome, suggested to have important roles in biomineralization. The increased hits in aromatic compounds, fatty acid and secondary metabolism subsystems hint at an important chemically mediated interaction in which a functional job partition among eukaryal, archaeal and bacterial groups allows the rhodolith holobiont to thrive in the global ocean. High rates of photosynthesis were measured for Abrolhos rhodoliths (52.16 μmol carbon m(-2 )s(-1)), allowing the entire Abrolhos rhodolith bed to produce 5.65 × 10(5) tons C per day. This estimate illustrates the great importance of the Abrolhos rhodolith beds for dissolved carbon production in the South Atlantic Ocean.

  13. Physiologic and metagenomic attributes of the rhodoliths forming the largest CaCO3 bed in the South Atlantic Ocean

    Science.gov (United States)

    Cavalcanti, Giselle S; Gregoracci, Gustavo B; dos Santos, Eidy O; Silveira, Cynthia B; Meirelles, Pedro M; Longo, Leila; Gotoh, Kazuyoshi; Nakamura, Shota; Iida, Tetsuya; Sawabe, Tomoo; Rezende, Carlos E; Francini-Filho, Ronaldo B; Moura, Rodrigo L; Amado-Filho, Gilberto M; Thompson, Fabiano L

    2014-01-01

    Rhodoliths are free-living coralline algae (Rhodophyta, Corallinales) that are ecologically important for the functioning of marine environments. They form extensive beds distributed worldwide, providing a habitat and nursery for benthic organisms and space for fisheries, and are an important source of calcium carbonate. The Abrolhos Bank, off eastern Brazil, harbors the world's largest continuous rhodolith bed (of ∼21 000 km2) and has one of the largest marine CaCO3 deposits (producing 25 megatons of CaCO3 per year). Nevertheless, there is a lack of information about the microbial diversity, photosynthetic potential and ecological interactions within the rhodolith holobiont. Herein, we performed an ecophysiologic and metagenomic analysis of the Abrolhos rhodoliths to understand their microbial composition and functional components. Rhodoliths contained a specific microbiome that displayed a significant enrichment in aerobic ammonia-oxidizing betaproteobacteria and dissimilative sulfate-reducing deltaproteobacteria. We also observed a significant contribution of bacterial guilds (that is, photolithoautotrophs, anaerobic heterotrophs, sulfide oxidizers, anoxygenic phototrophs and methanogens) in the rhodolith metagenome, suggested to have important roles in biomineralization. The increased hits in aromatic compounds, fatty acid and secondary metabolism subsystems hint at an important chemically mediated interaction in which a functional job partition among eukaryal, archaeal and bacterial groups allows the rhodolith holobiont to thrive in the global ocean. High rates of photosynthesis were measured for Abrolhos rhodoliths (52.16 μmol carbon m−2 s−1), allowing the entire Abrolhos rhodolith bed to produce 5.65 × 105 tons C per day. This estimate illustrates the great importance of the Abrolhos rhodolith beds for dissolved carbon production in the South Atlantic Ocean. PMID:23985749

  14. Physiologic and metagenomic attributes of the rhodoliths forming the largest CaCO3 bed in the South Atlantic Ocean.

    Science.gov (United States)

    Cavalcanti, Giselle S; Gregoracci, Gustavo B; dos Santos, Eidy O; Silveira, Cynthia B; Meirelles, Pedro M; Longo, Leila; Gotoh, Kazuyoshi; Nakamura, Shota; Iida, Tetsuya; Sawabe, Tomoo; Rezende, Carlos E; Francini-Filho, Ronaldo B; Moura, Rodrigo L; Amado-Filho, Gilberto M; Thompson, Fabiano L

    2014-01-01

    Rhodoliths are free-living coralline algae (Rhodophyta, Corallinales) that are ecologically important for the functioning of marine environments. They form extensive beds distributed worldwide, providing a habitat and nursery for benthic organisms and space for fisheries, and are an important source of calcium carbonate. The Abrolhos Bank, off eastern Brazil, harbors the world's largest continuous rhodolith bed (of ∼21,000 km(2)) and has one of the largest marine CaCO3 deposits (producing 25 megatons of CaCO3 per year). Nevertheless, there is a lack of information about the microbial diversity, photosynthetic potential and ecological interactions within the rhodolith holobiont. Herein, we performed an ecophysiologic and metagenomic analysis of the Abrolhos rhodoliths to understand their microbial composition and functional components. Rhodoliths contained a specific microbiome that displayed a significant enrichment in aerobic ammonia-oxidizing betaproteobacteria and dissimilative sulfate-reducing deltaproteobacteria. We also observed a significant contribution of bacterial guilds (that is, photolithoautotrophs, anaerobic heterotrophs, sulfide oxidizers, anoxygenic phototrophs and methanogens) in the rhodolith metagenome, suggested to have important roles in biomineralization. The increased hits in aromatic compounds, fatty acid and secondary metabolism subsystems hint at an important chemically mediated interaction in which a functional job partition among eukaryal, archaeal and bacterial groups allows the rhodolith holobiont to thrive in the global ocean. High rates of photosynthesis were measured for Abrolhos rhodoliths (52.16 μmol carbon m(-2 )s(-1)), allowing the entire Abrolhos rhodolith bed to produce 5.65 × 10(5) tons C per day. This estimate illustrates the great importance of the Abrolhos rhodolith beds for dissolved carbon production in the South Atlantic Ocean. PMID:23985749

  15. Tropical Atlantic SSTS at the Last Glacial Maximum derived from Sr/Ca ratios of fossil coral

    Science.gov (United States)

    Cohen, A. L.; Saenger, C. P.

    2006-12-01

    The sensitivity of the tropics to climate change is a particularly controversial issue in paleoclimatology. At the heart of this controversy are disagreements amongst different proxy datasets regarding the amplitude of glacial-interglacial changes in temperature, particularly at the sea surface. Data obtained from the aragonitic skeletons of massive reef corals have contributed in no small measure to the debate, yielding LGM and deglacial SSTs 5-6°C cooler than today (Guilderson et al., 1994; McCulloch et al., 1999; Correge et al., 2004), that imply a high sensitivity of Earth's climate to changes in boundary conditions (Crowley, 2000). We used SIMS ion microprobe to analyze Sr/Ca ratios of small pieces of Montastrea coral retrieved from a Barbados drillcore (Guilderson et al., 2001). U/Th dates place the samples between 22 and 24 kyr BP. Localized areas of dissolution and re-growth of secondary (diagenetic) aragonite crystals were identified at centers of septa. Sr/Ca ratios of these crystals were higher than Sr/Ca ratios of original coral crystals preserved in adjacent fasciculi and yielded relatively cooler derived SSTs. The original coral crystals, recognized by their size and orientation, were selectively targeted for analysis using a 20 micron-diameter sample spot. Our calibration study using modern corals from Bermuda, St Croix (USVI) and Barbados indicates that Montastrea Sr/Ca is strongly correlated with SST and with annual extension (growth) rate (Saenger et al., 2006). Growth rate of the fossil corals was determined from measurement of daily growth bands identified in petrographic thin-sections. Application of a growth-dependent Sr/Ca-T calibration yielded Barbados SSTs that were, on average, 2.5°C cooler than today during the LGM and ~1°C cooler than today during Heinrich Event 2. Our LGM SSTs are consistent with the original CLIMAP estimates (CLIMAP, 1976) and with more recent Mg/Ca-based SSTs derived from calcitic foraminifera in the Caribbean

  16. Differential changes in growth patterns of anadromous brown trout and Atlantic salmon from the River Etneelva over a 25-year period

    OpenAIRE

    Fjørtoft, Helene Børretzen; Borgstrøm, Reidar; Skaala, Øystein

    2013-01-01

    Freshwater and marine growth of anadromous brown trout (Salmo trutta) and Atlantic salmon (Salmo salar) from the River Etneelva was analysed in relation to river, fjord and ocean temperatures during the periods 1976-1982 and 2000-2007. Anadromous brown trout grew more slowly through their first and second summers in the sea during the last observation period compared to the first period, and there were more growth checks in the scales sampled from the last period. The reduced growth in length...

  17. A simulated lagged response of the North Atlantic Oscillation to the solar cycle over the period 1960–2009

    International Nuclear Information System (INIS)

    Numerous studies have suggested an impact of the 11 year solar cycle on the winter North Atlantic Oscillation (NAO), with an increased tendency for positive (negative) NAO signals to occur at maxima (minima) of the solar cycle. Climate models have successfully reproduced this solar cycle modulation of the NAO, although the magnitude of the effect is often considerably weaker than implied by observations. A leading candidate for the mechanism of solar influence is via the impact of ultraviolet radiation variability on heating rates in the tropical upper stratosphere, and consequently on the meridional temperature gradient and zonal winds. Model simulations show a zonal mean wind anomaly that migrates polewards and downwards through wave–mean flow interaction. On reaching the troposphere this produces a response similar to the winter NAO. Recent analyses of observations have shown that solar cycle–NAO link becomes clearer approximately three years after solar maximum and minimum. Previous modelling studies have been unable to reproduce a lagged response of the observed magnitude. In this study, the impact of solar cycle on the NAO is investigated using an atmosphere–ocean coupled climate model. Simulations that include climate forcings are performed over the period 1960–2009 for two solar forcing scenarios: constant solar irradiance, and time-varying solar irradiance. We show that the model produces significant NAO responses peaking several years after extrema of the solar cycle, persisting even when the solar forcing becomes neutral. This confirms suggestions of a further component to the solar influence on the NAO beyond direct atmospheric heating and its dynamical response. Analysis of simulated upper ocean temperature anomalies confirms that the North Atlantic Ocean provides the memory of the solar forcing required to produce the lagged NAO response. These results have implications for improving skill in decadal predictions of the European and North

  18. Changes in North Atlantic deep-sea temperature during climatic fluctuations of the last 25,000 years based on ostracode Mg/Ca ratios

    Science.gov (United States)

    Dwyer, Gary S.; Cronin, Thomas M.; Baker, Paul A.; Rodriguez-Lazaro, Julio

    2000-01-01

    We reconstructed three time series of last glacial-to-present deep-sea temperature from deep and intermediate water sediment cores from the western North Atlantic using Mg/Ca ratios of benthic ostracode shells. Although the Mg/Ca data show considerable variability (“scatter”) that is common to single-shell chemical analyses, comparisons between cores, between core top shells and modern bottom water temperatures (BWT), and comparison to other paleo-BWT proxies, among other factors, suggest that multiple-shell average Mg/Ca ratios provide reliable estimates of BWT history at these sites. The BWT records show not only glacial-to-interglacial variations but also indicate BWT changes during the deglacial and within the Holocene interglacial stage. At the deeper sites (4500- and 3400-m water depth), BWT decreased during the last glacial maximum (LGM), the late Holocene, and possibly during the Younger Dryas. Maximum deep-sea warming occurred during the latest deglacial and early Holocene, when BWT exceeded modern values by as much as 2.5°C. This warming was apparently most intense around 3000 m, the depth of the modern-day core of North Atlantic deep water (NADW). The BWT variations at the deeper water sites are consistent with changes in thermohaline circulation: warmer BWT signifies enhanced NADW influence relative to Antarctic bottom water (AABW). Thus maximum NADW production and associated heat flux likely occurred during the early Holocene and decreased abruptly around 6500 years B.P., a finding that is largely consistent with paleonutrient studies in the deep North Atlantic. BWT changes in intermediate waters (1000-m water depth) of the subtropical gyre roughly parallel the deep BWT variations including dramatic mid-Holocene cooling of around 4°C. Joint consideration of the Mg/Ca-based BWT estimates and benthic oxygen isotopes suggests that the cooling was accompanied by a decrease in salinity at this site. Subsequently, intermediate waters warmed to modern

  19. Reproduction period of Mimagoniates microlepis, from an Atlantic Forest Stream in Southern Brazil

    OpenAIRE

    Marcelo Rennó Braga; José Marcelo Rocha Aranha; Jean Ricardo Vitule

    2008-01-01

    Mimagoniates microlepis was collected between January and December/2002. Three sample points were chosen at higher, medium and lower portions of Ribeirão river, located at the east of Paraná state. The reproduction period was observed by the frequency of gonad developmental stages, variation of the gonosomatic relation (RGS) and gonad condition (K). The average length at the first sexual maturity (L50) and the average length when 100% of individuals were adults (L100) were calculated. The int...

  20. Influence of the Saharan Air Layer on Atlantic Tropical Cyclone Formation during the Period 1-12 September 2003

    Institute of Scientific and Technical Information of China (English)

    PAN Weiyu; WU Liguang; Chung-Lin SHIE

    2011-01-01

    Atmospheric Infrared Sounder (AIRS) data show that the Saharan air layer (SAL) is a dry, warm, and well-mixed layer between 950 and 500 hPa over the tropical Atlantic, extending westward from the African coast to the Caribbean Sea. The formations of both Hurricane Isabel and Tropical Depression 14 (TD14)were accompanied with outbreaks of SAL air during the period 1-12 September 2003. although TD14 failed to develop into a named tropical cyclone. The influence of the SAL on their formations is investigated by examining data from satellite observations and numerical simulations, in which AIRS data are incorporated into the MM5 model through the nudging technique. Analyses of the AIRS and simulation data suggest that the SAL may have played two roles in the formation of tropical cyclones during the period 1-12 September 2003. First, the outbreaks of SAL air on 3 and 8 September enhanced the transverse-vertical circulation with the rising motion along the southern edge of the SAL and the sinking motion inside the SAL, triggering the development of two tropical disturbances associated with Hurricane Isabel and TD14. Second, in addition to the reduced environmental humidity and enhanced static stability in the lower troposphere, the SAL dry air intruded into the inner region of these tropical disturbances as their cyclonic flows became strong. This effect may have slowed down the formation of Isabel and inhibited TD14 becoming a named tropical cyclone, while the enhanced vertical shear contributed little to tropical cyclone formation during this period. The 48-h trajectory calculations confirm that the parcels from the SAL can be transported into the inner region of an incipient tropical cyclone.

  1. Influence of the Saharan Air Layer on Atlantic tropical cyclone formation during the period 1-12 September 2003

    Science.gov (United States)

    Pan, Weiyu; Wu, Liguang; Shie, Chung-Lin

    2011-01-01

    Atmospheric Infrared Sounder (AIRS) data show that the Saharan air layer (SAL) is a dry, warm, and well-mixed layer between 950 and 500 hPa over the tropical Atlantic, extending westward from the African coast to the Caribbean Sea. The formations of both Hurricane Isabel and Tropical Depression 14 (TD14) were accompanied with outbreaks of SAL air during the period 1-12 September 2003, although TD14 failed to develop into a named tropical cyclone. The influence of the SAL on their formations is investigated by examining data from satellite observations and numerical simulations, in which AIRS data are incorporated into the MM5 model through the nudging technique. Analyses of the AIRS and simulation data suggest that the SAL may have played two roles in the formation of tropical cyclones during the period 1-12 September 2003. First, the outbreaks of SAL air on 3 and 8 September enhanced the transverse-vertical circulation with the rising motion along the southern edge of the SAL and the sinking motion inside the SAL, triggering the development of two tropical disturbances associated with Hurricane Isabel and TD14. Second, in addition to the reduced environmental humidity and enhanced static stability in the lower troposphere, the SAL dry air intruded into the inner region of these tropical disturbances as their cyclonic flows became strong. This effect may have slowed down the formation of Isabel and inhibited TD14 becoming a named tropical cyclone, while the enhanced vertical shear contributed little to tropical cyclone formation during this period. The 48-h trajectory calculations confirm that the parcels from the SAL can be transported into the inner region of an incipient tropical cyclone.

  2. Reproduction period of Mimagoniates microlepis, from an Atlantic Forest Stream in Southern Brazil

    Directory of Open Access Journals (Sweden)

    Marcelo Rennó Braga

    2008-04-01

    Full Text Available Mimagoniates microlepis was collected between January and December/2002. Three sample points were chosen at higher, medium and lower portions of Ribeirão river, located at the east of Paraná state. The reproduction period was observed by the frequency of gonad developmental stages, variation of the gonosomatic relation (RGS and gonad condition (K. The average length at the first sexual maturity (L50 and the average length when 100% of individuals were adults (L100 were calculated. The intensity of the reproductive activity (IAR was estimated at each sample point. The reproduction period started in the winter and ended at the end of spring. The high values of IAR encountered demonstrated that the reproductive activity occurred in the whole study area, mainly at the middle portion of the river. Apparently M. microlepis synchronize its fecundation and spawning with the rain regimes using the most suitable times for the cospecific encounters and offspring survival.Exemplares de Mimagoniates microlepis foram coletados entre janeiro e dezembro de 2002. Foram escolhidos três pontos amostrais localizados em regiões a montante, média e a jusante do rio Ribeirão no litoral do Paraná. A época reprodutiva foi determinada através da freqüência de estágios de desenvolvimento das gônadas, índice gonadosomático (RGS e fator de condição gonadal (K. O comprimento médio da primeira maturação (L50 e o comprimento médio em que 100% dos indivíduos são adultos (L100 foi calculado. Também foi estimado o índice de atividade reprodutiva (IAR em cada ponto amostral. O período reprodutivo teve inicio durante o inverno e terminou ao final da primavera. Os valores altos do IAR demonstram que a atividade reprodutiva ocorre em toda área estudada e principalmente na porção média do rio. Aparentemente M. microlepis sincroniza sua fecundação e desova com o ciclo das chuvas, utilizando os momentos mais adequados para encontros coespecíficos e para

  3. The optimal period of Ca-EDTA treatment for parthenogenetic activation of porcine oocytes during maturation culture

    Science.gov (United States)

    MORITA, Yasuhiro; TANIGUCHI, Masayasu; TANIHARA, Fuminori; ITO, Aya; NAMULA, Zhao; DO, Lanh Thi Kim; TAKAGI, Mitsuhiro; TAKEMOTO, Tatsuya; OTOI, Takeshige

    2016-01-01

    The changes triggered by sperm-induced activation of oocytes, which are required for normal oocyte development, can be mediated by other agents, thereby inducing the parthenogenesis. In this study, we exposed porcine oocytes to 1 mM Ca-EDTA, a metal-ion chelator, at various intervals during 48 hr of in vitro maturation to determine the optimum period of Ca-EDTA treatment for parthenogenetic activation. When the oocytes were cultured with or without Ca-EDTA from 36 hr (post-12), 24 hr (post-24), 12 hr (post-36) and 0 hr (post-48) after the start of maturation culture, the blastocyst formation rates were significantly higher (P<0.05) in the post-24, post-36 and post-48 groups (3.3%, 4.0% and 2.6%, respectively) than those in the control group without treatment (0%). Furthermore, when the oocytes were cultured with Ca-EDTA for 0 hr (control), 12 hr (pre-12), 24 hr (pre-24), 36 hr (pre-36) and 48 hr (pre-48) from the start of maturation culture, the oocytes formed blastocysts only in the pre-36 and pre-48 groups (0.4% or 0.8%, respectively). Pronuclei (<66.7%) were observed only when the periods of Ca-EDTA treatment were more than 12 hr during maturation culture. In the control group, no pronuclei were detected. Our findings demonstrate that porcine immature oocytes can be parthenogenetically activated by Ca-EDTA treatment for at least 24 hr to 36 hr during maturation culture, leading to pronucleus formation followed by the formation of blastocysts. PMID:26947170

  4. The wave climate of the Northeast Atlantic over the period 1955-1994: the WASA wave hindcast

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, H.; Rosenthal, W.; Stawarz, M. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Gewaesserphysik; Carretero, J.C.; Gomez, M.; Lozano, I.; Serrano, O. [Programa de Clima Maritimo (Puertos del Estado), Madrid (Spain); Reistad, M. [Det Norske Meteorologiske Inst., Bergen (Norway)

    1997-12-31

    The European project ``waves and storms in the North Atlantic`` (WASA) has been set up to prove, or to disprove, hypotheses of a worsening storm and wave climate in the Northeast Atlantic and adjacent seas in the present century. A major obstacle for assessing changes in storm and wave conditions are inhomogeneities in the observational records, both in the local observations and in the analysed products, which usually produce an artificial increase of extreme winds and waves. Therefore, changes in the wave climate were assessed with a state-of-the-art wave model using wind analyses. Within the scope of the WASA project, a 40 year reconstruction (1955-1994) of the wave climate in the North Atlantic was completed using the WAM wave model. The input wind fields were assumed to be reasonably homogeneous with time in the area south of 70 N and east of 20 W, and it was expected that the hindcast wave data would reliably describe the space-time evolution of wave conditions in this area. The results of the hindcast experiment are presented in this article. The main conclusion was that the wave climate in most of the Northeast Atlantic and in the North Sea has undergone significant variations on time scales of decades. Part of variability was found to be related to the North Atlantic oscillation. As a general result we noted an increase of the maximum annual significant wave height over the last 40 years of about 5 to 10 cm/year for large parts of the Northeast Atlantic, north of the North Sea. There was also a slight increase of probabilities of high waves derived from conventional extreme value statistics in northwest approaches to the North Sea. Similar trends of the extreme waves were found in a scenario of future wave climate at a time of doubled C0{sub 2} concentration in the atmosphere. (orig.) 28 refs.

  5. Physiologic and metagenomic attributes of the rhodoliths forming the largest CaCO3 bed in the South Atlantic Ocean

    OpenAIRE

    Cavalcanti, Giselle S; Gregoracci, Gustavo B.; dos Santos, Eidy O; Silveira, Cynthia B; Meirelles, Pedro M.; Longo, Leila; Gotoh, Kazuyoshi; Nakamura, Shota; Iida, Tetsuya; Sawabe, Tomoo; Rezende, Carlos E; Francini-Filho, Ronaldo B.; Moura, Rodrigo L.; Amado-Filho, Gilberto M.; Thompson, Fabiano L.

    2013-01-01

    Rhodoliths are free-living coralline algae (Rhodophyta, Corallinales) that are ecologically important for the functioning of marine environments. They form extensive beds distributed worldwide, providing a habitat and nursery for benthic organisms and space for fisheries, and are an important source of calcium carbonate. The Abrolhos Bank, off eastern Brazil, harbors the world's largest continuous rhodolith bed (of ∼21 000 km2) and has one of the largest marine CaCO3 deposits (producing 25 me...

  6. FIT FOR PRINT: DEVELOPING AN INSTITUTIONAL MODEL OF SCIENTIFIC PERIODICAL PUBLISHING IN ENGLAND, 1665-CA. 1714.

    Science.gov (United States)

    Moxham, N

    2015-09-20

    This paper explores the contested afterlife of Philosophical Transactions following the death of its founder, Henry Oldenburg. It investigates the complex interrelation between the institution and the periodical at a time when the latter was supposedly independent, and outlines the competing proposals for institutional publishing in science contemplated in the Royal Society, linking some publications that were actually attempted to those proposals and to the Society's attempts to revitalize its experimental programme between 1677 and 1687. It argues that the Society was concerned to produce experimental natural knowledge over which it could claim ownership, and intended this work for publication in other venues than Transactions, whereas the periodical was seen as a more suitable site for work reported to the Society than for research that the institution had primarily produced. It was only from the early 1690s, after the collapse of the Society's experimental programme, that Transactions gradually became a more straightforward reflection of the mainstream of Royal Society activity, paving the way for its formal reinvention as the official publication of the Society in 1752.

  7. Inter-annual variability of aerosol optical depth over the tropical Atlantic Ocean based on MODIS-Aqua observations over the period 2002-2012

    Science.gov (United States)

    Gkikas, Antonis; Hatzianastassiou, Nikolaos

    2013-04-01

    The tropical Atlantic Ocean is affected by dust and biomass burning aerosol loads transported from the western parts of the Saharan desert and the sub-Sahel regions, respectively. The spatial and temporal patterns of this transport are determined by the aerosol emission rates, their deposition (wet and dry), by the latitudinal shift of the Intertropical Convergence Zone (ITCZ) and the prevailing wind fields. More specifically, in summer, Saharan dust aerosols are transported towards the Atlantic Ocean, even reaching the Gulf of Mexico, while in winter the Atlantic Ocean transport takes place in more southern latitudes, near the equator, sometimes reaching the northern parts of South America. In the later case, dust is mixed with biomass burning aerosols originating from agricultural activities in the sub-Sahel, associated with prevailing north-easterly airflow (Harmattan winds). Satellite observations are the appropriate tool for describing this African aerosol export, which is important to atmospheric, oceanic and climate processes, offering the advantage of complete spatial coverage. In the present study, we use satellite measurements of aerosol optical depth at 550nm (AOD550nm), on a daily and monthly basis, derived from MODIS-Aqua platform, at 1ox1o spatial resolution (Level 3), for the period 2002-2012. The primary objective is to determine the pixel-level and regional mean anomalies of AOD550nm over the entire study period. The regime of the anomalies of African export is interpreted in relation to the aerosol source areas, precipitation, wind patterns and temporal variability of the North Atlantic Oscillation Index (NAOI). In order to ensure availability of AOD over the Sahara desert, MODIS-Aqua Deep Blue products are also used. As for precipitation, Global Precipitation Climatology Project (GPCP) data at 2.5ox2.5o are used. The wind fields are taken from the National Center for Environmental Prediction (NCEP). Apart from the regime of African aerosol export

  8. Reduced admixture of North Atlantic Deep Water to the deep central South Pacific during the last two glacial periods

    Science.gov (United States)

    Molina-Kescher, Mario; Frank, Martin; Tapia, Raúl; Ronge, Thomas A.; Nürnberg, Dirk; Tiedemann, Ralf

    2016-06-01

    The South Pacific is a sensitive location for the variability of the global oceanic thermohaline circulation given that deep waters from the Atlantic Ocean, the Southern Ocean, and the Pacific Basin are exchanged. Here we reconstruct the deep water circulation of the central South Pacific for the last two glacial cycles (from 240,000 years ago to the Holocene) based on radiogenic neodymium (Nd) and lead (Pb) isotope records complemented by benthic stable carbon data obtained from two sediment cores located on the flanks of the East Pacific Rise. The records show small but consistent glacial/interglacial changes in all three isotopic systems with interglacial average values of -5.8 and 18.757 for ɛNd and 206Pb/204Pb, respectively, whereas glacial averages are -5.3 and 18.744. Comparison of this variability of Circumpolar Deep Water (CDW) to previously published records along the pathway of the global thermohaline circulation is consistent with reduced admixture of North Atlantic Deep Water to CDW during cold stages. The absolute values and amplitudes of the benthic δ13C variations are essentially indistinguishable from other records of the Southern Hemisphere and confirm that the low central South Pacific sedimentation rates did not result in a significant reduction of the amplitude of any of the measured proxies. In addition, the combined detrital Nd and strontium (87Sr/86Sr) isotope signatures imply that Australian and New Zealand dust has remained the principal contributor of lithogenic material to the central South Pacific.

  9. Periodization

    OpenAIRE

    Lorenz, Daniel S.; Reiman, Michael P.; Walker, John C.

    2010-01-01

    Background: Clinicians are constantly faced with the challenge of designing training programs for injured and noninjured athletes that maximize healing and optimize performance. Periodization is a concept of systematic progression—that is, resistance training programs that follow predictable patterns of change in training variables. The strength training literature is abundant with studies comparing periodization schemes on uninjured, trained, and untrained athletes. The rehabilitation litera...

  10. Analysis of transfer prices in the North Atlantic petroleum industry for the period 1979-1984: A disaggregated approach

    International Nuclear Information System (INIS)

    An empirical study was conducted to verify the hypothesis that the multinational petroleum companies exporting to North Atlantic markets had abused transfer prices in order to evade taxes from 1979 to 1984. The investigations are based on an essentially econometric approach at a high level of disaggregation. The fixed coefficient model for the resulting panel data allows estimation of the defrayed prices by the affiliates during the multinational's internal exchanges, as well as the prices in the independent market. The empirical tests show that only certain affiliates have spent at prices different to those in the international market, and those were exclusively for the purchase of crude oil originating from certain countries. Even for these significant differences, no evident relationship is demonstrated between the rate of taxes on foreign profits in effect in the host countries and the transfer prices. 53 refs., 71 tabs

  11. Atlantic salmon require long-chain n-3 fatty acids for optimal growth throughout the seawater period

    OpenAIRE

    Rosenlund, Grethe; Torstensen, Bente E.; Stubhaug, Ingunn; Usman, Nafiha; Sissener, Nini H.

    2016-01-01

    The nutritional requirement for n-3 long-chain PUFA in fast-growing Atlantic salmon (Salmo salar) during grow out in the sea is not well documented. Diets were formulated with levels of EPA (20 : 5n-3) and DHA (22 : 6n-3) ranging from 1·3 to 7·4 % of fatty acids (4–24 g/kg feed). Two long-term trials were conducted through the seawater phase, the first at 6 and 12°C, and the second at 12°C. In the first trial, growth at both temperatures was significantly lower in fish fed 1·4 % EPA+DHA of to...

  12. Early enrichment effects on brain development in hatchery-reared Atlantic salmon (Salmo salar): no evidence for a critical period

    DEFF Research Database (Denmark)

    Näslund, Joacim; Aarestrup, Kim; Thomassen, Søren T.;

    2012-01-01

    In hatcheries, fish are normally reared in barren environments, which have been reported to affect their phenotypic development compared with wild conspecifics. In this study, Atlantic salmon (Salmo salar) alevins were reared in conventional barren hatchery trays or in either of two types...... of structurally enriched trays. We show that increased structural complexity during early rearing increased brain size in all investigated brain substructures. However, these effects disappeared over time after transfer to barren tanks for external feeding. Parallel to the hatchery study, a group of salmon parr...... trajectory. In contrast, our results indicate that brain growth is plastic in relation to environment. In addition, we show allometric growth in brain substructures over juvenile development, which suggests that comparisons between groups of different body size should be made with caution. These results can...

  13. Aerosol light absorption in the North Atlantic: trends and seasonal characteristics during the period 1989 to 2003

    Directory of Open Access Journals (Sweden)

    C. Junker

    2006-01-01

    Full Text Available Aerosol light attenuation on quartz fibre filters has been measured since February 1989 at the Mace Head Atmospheric Research station near Carna, Co. Galway, Ireland, using an Aethalometer. The frequency of occurrence of the hourly averaged aerosol absorption data is found to be bimodally distributed. The two modes result from clean marine air and anthropogenically polluted continental air both being advected to the station dependent on the prevailing wind direction. The hourly averages of the marine portion of the aerosol light absorption are found to follow closely a lognormal distribution with a geometric mean of 0.310 Mm-1. The hourly averages of continental sector aerosol absorption are neither normally nor lognormally distributed and have an arithmetic mean of 6.36 Mm-1, indicating the presence of anthropogenic sources for BC east of the Mace Head station. The time series of the monthly averaged attenuation coefficient σatt of both marine and continental sector aerosol shows an increase from 1989 to 1997 and a levelling off thereafter. The monthly maximum of marine sector σatt is found in May. Trend and seasonal characteristics of the clean marine aerosol attenuation coefficients observed at Mace Head appear to be driven by meteorological factors, as indicated by rainfall data and by trends in the North Atlantic Oscillation (NAO indices. The observed increasing trends of the continental sector σatt from 1989 up to 1997 are possibly related to changes in BC emissions over Ireland, calculated from UNSTAT (2002 fuel consumption data.

  14. A seesaw in Mediterranean precipitation during the Roman Period linked to millennial-scale changes in the North Atlantic

    NARCIS (Netherlands)

    Dermody, B.; Boer, H.J. de; Bierkens, M.F.P.; Weber, S.L.; Wassen, M.J.; Dekker, S.C.

    2012-01-01

    We present a reconstruction of the change in climatic humidity around the Mediterranean between 3000– 1000 yr BP. Using a range of proxy archives and model simulations we demonstrate that climate during this period was typified by a millennial-scale seesaw in climatic humidity between Spain and Isra

  15. In search of "Organ III" strata-a sedimentary record of the Medieval Warm Period (ca. AD 900 to 1300)

    Science.gov (United States)

    The period AD 900 to 1300, internationally referred to as the Medieval Warm Period, is a critical time for the archaeological record of the Southwestern USA. During the Medieval Warm Period both alluvial and eolian sedimentation increased, but not to the magnitude of the middle Holocene (the Altithe...

  16. Multiregional periodic matrix for modeling the population dynamics of sardine (Sardina pilchardus) along the moroccan atlantic coast: management elements for fisheries.

    Science.gov (United States)

    Serghini, Mansour; Boutayeb, Abdesslam; Auger, Pierre; Charouki, Najib; Ramzi, Azeddine; Ettahiri, Omar; Tchuente, Maurice

    2009-12-01

    In this paper, we present a deterministic time discrete mathematical model based on multiregional periodic matrices to describe the dynamics of Sardina pilchardus in the Central Atlantic area of the Moroccan coast. This model deals with two stages (immature and mature) and three spatial zones where sardines are supposed to migrate from one zone to another. The population dynamics is described by an autonomous recurrence equation N(t + 1) = A.N(t), where A is a positive matrix whose entries are estimated using data collected during biannual acoustic surveys carried out from 2001 to 2003 onboard the Norwegian research vessel "Dr Fridtjof Nansen". The dominant eigenvalue lambda of A that gives the long-term growth rate of fish population is smaller than one. This agrees with the stock decrease observed in the data collected. We show that lambda is highly sensitive to the recruitment rate and much less sensitive to the reproduction rate. These results can clearly be used to define an efficient scenario in order to fight for instance against a stock decrease. PMID:19842047

  17. Hepatic retention and toxicological responses during feeding and depuration periods in Atlantic salmon ( Salmo salar ) fed graded levels of the synthetic antioxidant, butylated hydroxytoluene.

    Science.gov (United States)

    Holaas, Eivind; Bohne, Victoria B; Hamre, Kristin; Arukwe, Augustine

    2008-12-10

    The human safety aspects of seafood production require the expansion of vital knowledge of both nutrients and possible contaminants along the entire production chain. Thus, production of safer seafood can be achieved by using feed materials that are low in contaminants, while maintaining balanced nutrition, in order to secure optimal fish and consumer health. Our understanding of primary responses of fish health and production related diseases, as well as biological processes that influence carry-over and lowering of contaminants in farmed fish, will contribute to a sustainable production of safer seafood products. Therefore, we have studied the liver deposition and toxicological effects in salmon fed graded levels of BHT during a 12-week feeding followed by a 2-week depuration period using chemical, molecular, and catalytic assays. In general, our data showed that BHT was significantly retained in the liver and selectively modulated toxicological responses in the xenobiotic biotransformation pathways during the feeding period. Specifically, BHT produced consistent dose- and time-specific gene expression patterns for AhR2alpha, AhR2beta, CYP1A1, CYP3A, UGT1, and GSTpi. The effect of BHT on the gene expression of biotransformation enzyme did not parallel enzyme activity levels, suggesting a possible inhibition by parent BHT or its metabolites. As a safety precaution, the production of farmed Atlantic salmon in Norway requires a mandatory 2-week depuration period prior to slaughtering and market delivery to ensure the elimination of veterinary medicaments, additives, and other undesirable components. Comparison of feeding and depuration periods showed that BHT was highly retained in fish liver, as only 8-13% of fed BHT was eliminated during the 2-week depuration period. This is just a part of the total concentration in the whole fish, since BHT may have been distributed and accumulated in other organs. Since BHT or its metabolites putatively inhibited

  18. Tropical Rain Forest and Climate Dynamics of the Atlantic Lowland, Southern Brazil, during the Late Quaternary

    Science.gov (United States)

    Behling, Hermann; Negrelle, Raquel R. B.

    2001-11-01

    Palynological analysis of a core from the Atlantic rain forest region in Brazil provides unprecedented insight into late Quaternary vegetational and climate dynamics within this southern tropical lowland. The 576-cm-long sediment core is from a former beach-ridge "valley," located 3 km inland from the Atlantic Ocean. Radio-carbon dates suggest that sediment deposition began prior to 35,000 14C yr B.P. Between ca. 37,500 and ca. 27,500 14C yr B.P. and during the last glacial maximum (LGM; ca. 27,500 to ca. 14,500 14C yr B.P.), the coastal rain forest was replaced by grassland and patches of cold-adapted forest. Tropical trees, such as Alchornea, Moraceae/Urticaceae, and Arecaceae, were almost completely absent during the LGM. Furthermore, their distributions were shifted at least 750 km further north, suggesting a cooling between 3°C and 7°C and a strengthening of Antarctic cold fronts during full-glacial times. A depauperate tropical rain forest developed as part of a successional sequence after ca. 12,300 14C yr B.P. There is no evidence that Araucaria trees occurred in the Atlantic lowland during glacial times. The rain forest was disturbed by marine incursions during the early Holocene period until ca. 6100 14C yr B.P., as indicated by the presence of microforaminifera. A closed Atlantic rain forest then developed at the study site.

  19. Impact of volcanism on the evolution of Lake Van (eastern Anatolia) III: Periodic (Nemrut) vs. episodic (Süphan) explosive eruptions and climate forcing reflected in a tephra gap between ca. 14 ka and ca. 30 ka

    Science.gov (United States)

    Schmincke, Hans-Ulrich; Sumita, Mari

    2014-09-01

    Fifteen Lateglacial to Holocene rhyolitic, dominantly primary tephra layers piston-cored and drilled (ICDP Paleovan drilling project) in western Lake Van (eastern Anatolia, Turkey) were precisely correlated to either of the two adjacent and active large volcanoes Nemrut and Süphan based on shard textures, mineralogy and mineral and glass compositions. The young peralkaline (comenditic to pantelleritic) primary rhyolitic Nemrut tephras are characterized by anorthoclase, hedenbergitic to augitic clinopyroxene, fayalitic olivine, minor quartz, and rare accessory chevkinite and zircon. Phenocrysts in subalkaline primary rhyolitic Süphan tephras are chiefly oligoclase-labradorite, with minor K-rich sanidine in some, biotite, amphibole, hypersthene, rare augitic clinopyroxene, relatively common allanite and rare zircon. Two contrasting explosive eruptive modes are distinguished from each other: episodic (Süphan) and periodic (Nemrut). The Lateglacial Süphan tephra swarm covers a short time interval of ca. 338 years between ca. 13,078 vy BP and 12,740 vy BP, eruptions having occurred statistically every ca. 42 years with especially short intervals between V-11 (reworked) and V-14. Causes for the strongly episodic Süphan explosive behavior might include seismic triggering of a volcano-magma system unable to erupt explosively without the benefit of external triggering, as reflected in pervasive faulting preceding the Süphan tephra swarm. Seismic triggering may have caused the rise of more mafic ("trachyandesitic") parent magma, heating near-surface pockets of highly evolved magma - that might have formed silicic domes during this stage of volcano evolution - resulting in ascent and finally explosive fragmentation of magma essentially by external factors, probably significantly enhanced by magma-water/ice interaction. Explosive eruptions of the Nemrut volcano system, interpreted to be underlain by a large fractionating magma reservoir, follow a more periodic mode of (a

  20. The synchronization of palaeoclimatic events in the North Atlantic region during Greenland Stadial 3 (ca 27.5 to 23.3 kyr b2k)

    DEFF Research Database (Denmark)

    Hibbert, F.D.; Peters, C.; Rasmussen, Sune Olander;

    2012-01-01

    Two high resolution marine sediment cores located 83 km apart in the NE Atlantic have been studied: MD95-2006 (Barra Fan; 57°01.82 N, 10°03.48 W; 2120 m water depth) and MD04-2822 (Rockall Trough; 56°50.54 N, 11°22.96 W; 2344 m water depth). The records are anchored to the NGRIP ice core stratigr......Two high resolution marine sediment cores located 83 km apart in the NE Atlantic have been studied: MD95-2006 (Barra Fan; 57°01.82 N, 10°03.48 W; 2120 m water depth) and MD04-2822 (Rockall Trough; 56°50.54 N, 11°22.96 W; 2344 m water depth). The records are anchored to the NGRIP ice core...

  1. New results to discuss possibility of irrigation in Bat (Wadi Sharsah, northwestern Oman) before Hafit period (ca. 3100-2700 BCE)

    Science.gov (United States)

    Fouache, Eric; Desruelles, Stéphane; Eddargach, Wassel; Cammas, Cecilia; Wattez, Julia; Martin, Chloé; Tengberg, Margareta; Beuzen-Waller, Tara; Cable, Charlotte; Thornton, Christopher

    2014-05-01

    Registered as a World Heritage Site by UNESCO in 1989, the extensive archaeological site of Bat is situated within the Wadi Sharsah and around the modern village and palm grove of Bat, 24 km from the modern city of Ibri in northwestern Oman. The archaeological remains from the Bronze Age excavated by the Bat Archaeological Project are located in two mains areas. The northern area consists of a chain of low limestone hills cut by wadi tributaries leading to the main Wadi Sharsah. It is characterised by an exceptionnally high density of graves from two successive Bronze Age periods : Hafit (ca. 3100-2700 BCE) and Umm an-Nar (ca. 2700-2000 BCE). South of the Bat cemetery, in the flat part of the valley, there are several large circular structures (known historically as « towers ») and remains from both Hafit and Umm an-Nar periods, as well as later periods. Geomorphological mapping of the floodplain, associated with archaeological survey, have identified walls suggesting that during the Umm an-Nar period there was a system of irrigation which controlled flood water. Sedimentological, malacological, C14 dating and micromorphological studies of a 10 m long and 2.5 m high section located 143 m northeast of the Tower 1146 on the left bank of a small tributary of the Wadi Sharsah provide strong argument for the presence of an irrigation system that began before the Hafit period. New C14 datings confirm this hypothesis. Botanical macro-remains collected during the excavation of early Bronze Age structures at Bat further indicate the presence of date palm gardens since the 3rd millenium BCE allowing the cultivation of several crop species, in particular cereals. Most generally the global palaeoenvironmental reconstruction from our data supports a model of a general trend of aridification from Bronze Age to iron Age. Key words : Bronze Age, Holocene, Geomoephology, Micromorphology, Irrigation, Oman.

  2. Aerosol properties associated with air masses arriving into the North East Atlantic during the 2008 Mace Head EUCAARI intensive observing period: an overview

    Directory of Open Access Journals (Sweden)

    D. Worsnop

    2009-12-01

    Full Text Available As part of the EUCAARI Intensive Observing Period, a 4-week campaign to measure aerosol physical, chemical and optical properties, atmospheric structure, and cloud microphysics was conducted from mid-May to mid-June 2008 at the Mace Head Atmospheric Research Station, located at the interface of Western Europe and the NE Atlantic and centered on the west Irish coastline. During the campaign, continental air masses comprising both young and aged continental plumes were encountered, along with polar, Arctic and tropical air masses. Polluted-continental aerosol concentrations were of the order of 3000 cm−3, while background marine air aerosol concentrations were between 400–600 cm−3. The highest marine air concentrations occurred in polar air masses in which a 15 nm nucleation mode, with concentration of 1100 cm−3, was observed and attributed to open ocean particle formation. Black carbon concentrations in polluted air were between 300–400 ng m−3, and in clean marine air were less than 50 ng m−3. Continental air submicron chemical composition (excluding refractory sea salt was dominated by organic matter, closely followed by sulphate mass. Although the concentrations and size distribution spectral shape were almost identical for the young and aged continental cases, hygroscopic growth factors (GF and cloud condensation nuclei (CCN to total condensation nuclei (CN concentration ratios were significantly less in the younger pollution plume, indicating a more oxidized organic component to the aged continental plume. The difference in chemical composition and hygroscopic growth factor appear to result in a 40–50% impact on aerosol scattering coefficients and Aerosol Optical Depth, despite almost identical aerosol microphysical properties in both cases, with the higher values been recorded for the more aged case. For the CCN/CN ratio, the highest ratios were seen in the more age plume

  3. Aerosol properties associated with air masses arriving into the North East Atlantic during the 2008 Mace Head EUCAARI intensive observing period: an overview

    Directory of Open Access Journals (Sweden)

    M. Dall'Osto

    2010-09-01

    Full Text Available As part of the EUCAARI Intensive Observing Period, a 4-week campaign to measure aerosol physical, chemical and optical properties, atmospheric structure, and cloud microphysics was conducted from mid-May to mid-June, 2008 at the Mace Head Atmospheric Research Station, located at the interface of Western Europe and the N. E. Atlantic and centered on the west Irish coastline. During the campaign, continental air masses comprising both young and aged continental plumes were encountered, along with polar, Arctic and tropical air masses. Polluted-continental aerosol concentrations were of the order of 3000 cm−3, while background marine air aerosol concentrations were between 400–600 cm−3. The highest marine air concentrations occurred in polar air masses in which a 15 nm nucleation mode, with concentration of 1100 cm−3, was observed and attributed to open ocean particle formation. Continental air submicron chemical composition (excluding refractory sea salt was dominated by organic matter, closely followed by sulphate mass. Although the concentrations and size distribution spectral shape were almost identical for the young and aged continental cases, hygroscopic growth factors (GF and cloud condensation nuclei (CCN to total condensation nuclei (CN concentration ratios were significantly less in the younger pollution plume, indicating a more oxidized organic component to the aged continental plume. The difference in chemical composition and hygroscopic growth factor appear to result in a 40–50% impact on aerosol scattering coefficients and Aerosol Optical Depth, despite almost identical aerosol microphysical properties in both cases, with the higher values been recorded for the more aged case. For the CCN/CN ratio, the highest ratios were seen in the more age plume. In marine air, sulphate mass dominated the sub-micron component, followed by water soluble organic carbon, which, in turn, was dominated by

  4. Sea Surface Temperature Variability in the Atlantic Sector of the Southern Ocean (odp Site 1090) across the Middle Pleistocene Transition Inferred from Mg/Ca Ratios in Planktonic Foraminifera.

    Science.gov (United States)

    Rodriguez-Sanz, L.; Mortyn, P. G.; Martinez-Garcia, A.; Rosell-Mele, A.

    2009-04-01

    Many paleoceanographic studies have focused on the Middle Pleistocene Transition (MPT), since during this period of time the frequency of glacial-interglacial (G/I) cycles changed from 41ky to 100ky, despite no fundamental differences in insolation forcing. Concomitant changes in ocean circulation and glacier dynamics, as well as a decrease in atmospheric CO2 concentrations have been suggested to be involved in this climatic transition. However, controversy on specific cause-effect mechanisms still remains. The Southern Ocean plays a key role in the ocean circulation system and global climate not only due to the exchange among different water masses from major basins, but also because it facilitates CO2 exchange between the deep ocean and the atmosphere. The Ocean Drilling Program (ODP) Site 1090, located in the present- day Subantarctic zone (42°54.8´S - 8°54´E, 3702m), spans the entire MPT, and allows sampling at moderate temporal resolution (2ky). The sediments accumulated above the calcium carbonate compensation depth, ensuring the preservation of calcareous microfossils through G/I periods. Sea surface temperature (SST) was reconstructed with planktonic foraminiferal Mg/Ca ratios (from Neogloboquadrina pachyderma (sinistral)), spanning the MPT from 1250-588Ka. Our results show G/I temperature variability between 4.2 and 14.2 °C when we use the Nurnberg (1995) equation to calculate SST, and between 2.9 and 11.9 °C when the Elderfield and Ganssen (2000) equation is used. The variability obtained from the latter calibration is in good agreement with that derived from other paleothermometers: Modern Analog Technique (MAT) and organic biomarkers from calcareous phytoplankton (UK37). Differences between Mg/Ca calibrations are probably the result of contrasting materials and approaches (culture vs. core-top). SST showed the expected lower G/I variability around 1000ka, and an increase of G/I variability after 900ka. Proxy comparison between our new Mg/Ca

  5. 不同时期外施Ca2+缓解辣椒淹水胁迫伤害的研究%The Impact of Different Ca2+ Spraying Period on Alleviating Pepper Injury Under the Waterlogging Stress

    Institute of Scientific and Technical Information of China (English)

    刘周斌; 杨博智; 欧立军; 邹学校

    2015-01-01

    以‘新优5号’辣椒为试材,研究不同时期叶面喷施Ca2+对淹水胁迫下辣椒幼苗农艺性状和生理生化指标的影响,探讨缓解辣椒淹水伤害的较佳喷施时期.研究发现,外源Ca2+能改善植株农艺性状,提高抗氧化酶活性和呼吸相关酶活性,增加脯氨酸和可溶性糖含量,降低相对电导率,减少MDA和·OH积累;淹水胁迫前(1d、2d)施用外源Ca2+,辣椒叶绿素含量、可溶性糖含量、CAT、POD、SOD、GR、ADH、SDH和MDH活性最高,相对电导率、LDH活性、MDA和·OH积累量最低,农艺性状显著优于其他时期;胁迫当天施用外源Ca2+脯氨酸含量最高;胁迫后(1d、2 d)施用外源Ca2+农艺性状、抗氧化酶系统、呼吸相关酶活性均差于其他时期.结果表明,Ca2+在一定程度上缓解了淹水胁迫造成的伤害,且以淹水胁迫前喷施外源Ca2+较佳.

  6. Last interglacial temperature seasonality reconstructed from tropical Atlantic corals

    Science.gov (United States)

    Brocas, William M.; Felis, Thomas; Obert, J. Christina; Gierz, Paul; Lohmann, Gerrit; Scholz, Denis; Kölling, Martin; Scheffers, Sander R.

    2016-09-01

    Reconstructions of last interglacial (LIG, MIS 5e, ∼127-117 ka) climate offer insights into the natural response and variability of the climate system during a period partially analogous to future climate change scenarios. We present well preserved fossil corals (Diploria strigosa) recovered from the southern Caribbean island of Bonaire (Caribbean Netherlands). These have been precisely dated by the 230Th/U-method to between 130 and 120 ka ago. Annual banding of the coral skeleton enabled construction of time windows of monthly resolved strontium/calcium (Sr/Ca) temperature proxy records. In conjunction with a previously published 118 ka coral record, our eight records of up to 37 years in length, cover a total of 105 years within the LIG period. From these, sea surface temperature (SST) seasonality and variability in the tropical North Atlantic Ocean is reconstructed. We detect similar to modern SST seasonality of ∼2.9 °C during the early (130 ka) and the late LIG (120-118 ka). However, within the mid-LIG, a significantly higher than modern SST seasonality of 4.9 °C (at 126 ka) and 4.1 °C (at 124 ka) is observed. These findings are supported by climate model simulations and are consistent with the evolving amplitude of orbitally induced changes in seasonality of insolation throughout the LIG, irrespective of wider climatic instabilities that characterised this period. The climate model simulations suggest that the SST seasonality changes documented in our LIG coral Sr/Ca records are representative of larger regions within the tropical North Atlantic. These simulations also suggest that the reconstructed SST seasonality increase during the mid-LIG is caused primarily by summer warming. A 124 ka old coral documents, for the first time, evidence of decadal SST variability in the tropical North Atlantic during the LIG, akin to that observed in modern instrumental records.

  7. Decadal-Scale Tropical North Atlantic Climate Variability Recorded in Slow Growing Cape Verde Corals

    Science.gov (United States)

    Moses, C. S.; Swart, P. K.; Dodge, R. E.; Helmle, K. P.; Thorrold, S.

    2002-12-01

    The decadal to century scale climate variability of the tropical North Atlantic has major implications for both neighboring coastal and inland areas. Changes in patterns of sea surface temperature (SST) and SST anomalies (SSTA) in the tropical North Atlantic are known to affect rainfall in Florida, South America, and sub-Saharan Africa, as well as the number of major hurricanes formed in the Atlantic. Because of the significance of these connections, it is important to further increase our predictive capacity for the recognition of trends and cycles in tropical North Atlantic SST and SSTA. Located at 15° N latitude off the west coast of sub-Saharan Africa, the Cape Verde Islands are an ideal geographic location to search for records of the Tropical North Atlantic Index (TNA). Such patterns are present in proxy indicators of climate (O, C, Sr/Ca and Mg/Ca) recorded in the skeletons of slow growing corals, such as Siderastrea radians, found in Cape Verde (growth rate = 1-2 mm/yr). These corals represent an archive for SST and SSTA records that exceed the instrumental period of the eastern tropical North Atlantic. We cored corals from several different locations within the Cape Verde archipelago and analyzed them for stable isotopes (δ13C and δ18O) and minor elements (Sr, Mg, and Ba). The δ18O signal present in these corals shows a distinct relationship to the TNA over the better part of the last 100 years. In addition, the δ18O record in several of these corals also records the onset of the latest Sahel (11°-18° N in Africa) drought which began in 1970. The Sr/Ca and Mg/Ca records of these corals indicate a slight warming of the waters around Cape Verde during the last 100 years, as well as accurately recording the El Niño events of 1982-83 and 1997-98. The correlations present between the records in these corals and the known instrumental record for the eastern tropical North Atlantic suggests that the fluctuations recorded in the proxy indicators may be

  8. Sea Surface Temperature Reconstruction Period 1993 - 2007 Based on Content Analysis of Coral Sr/Ca from the Region Labuan Bajo, Simeulue Island

    Directory of Open Access Journals (Sweden)

    Sri Yudawati Cahyarini

    2014-06-01

    Full Text Available DOI: 10.17014/ijog.v6i3.121Sea surface temperature (SST is one of the important parameters for (paleo climate studies. The long time series of SST data are required to understand more the climate change. Coral geochemical proxy such as Sr/Ca overcomes this problem. Coral can provide long time series of climate data continuously from present till hundreds years ago, even fossil (dead coral can do it till thousand years ago. In this study, Sr/Ca content of Porites coral within 10 m deep from Labuan Bajo, Simeulue Island was analyzed to reconstruct SST. Coral Sr/Ca shows a strong correlation with local SST in seasonal scale as well as in the annual mean scale. Reconstructed SST data show that the monsoon between 1993 2007 strongly influence the SST variation in the Simeulue region. It supposed that the seasonal variation signal strongly influence local SST than the annual mean signal such as El Nino.

  9. Variability in north tropical atlantic over the last 20 000 years and holocene gulf stream activity

    International Nuclear Information System (INIS)

    Modern oceanographical studies shown that most of the ocean heat content in the North Atlantic Western Boundary Current region is stored in the upper 400 meters. To study past heat content and Gulf Stream activity, we performed coupled analyses of oxygen isotopic and trace elemental composition on several foraminifera species to reconstruct upper water column temperature and salinity. Calcification depths of Globorotalia inflata, Globorotalia truncatulinoides and Pulleniatina obliquiloculata have been constrain by correlating modern hydrographic data to oxygen isotopic measurement of North Atlantic core-top samples. We found that the three deep-dwelling foraminifera species have a preferred habitat at the base of the seasonal thermocline (Cleroux et al, 2007). The same set of North Atlantic core-tops has been used to define relationships between trace elemental compositions and temperature. We established calibrations between Mg/Ca ratio or Sr/Ca ratio and temperature for the three deep-dwelling foraminifera (Cleroux et al, submitted). We apply this strategy on the core MD99-2203 located off Cape Hatteras where the Gulf Stream separate from the United States coast. High-resolution surface reconstructions over the Holocene show low amplitude periodic temperature and salinity changes that could be related to NAO type mechanisms. Large hydrological changes in sub-surface reflect variations of Labrador current and Mode Water influences. Using recent studies on Mode Water formation and Gulf Stream heat advection, we interpret our results in term of ocean heat content and Gulf Stream activity. (author)

  10. 2005 Atlantic Hurricanes Poster

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The 2005 Atlantic Hurricanes poster features high quality satellite images of 15 hurricanes which formed in the Atlantic Basin (includes Gulf of Mexico and...

  11. South Atlantic Shrimp System

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The SEFSC, in cooperation with the South Atlantic states, collects South Atlantic shrimp data from dealers and fishermen. These data are collected to provide catch,...

  12. Hydrographic changes in the subpolar North Atlantic at the MCA to LIA transition

    Science.gov (United States)

    Divine, Dmitry; Miettinen, Arto; Husum, Katrine; Koc, Nalan

    2016-04-01

    A network of four marine sediment cores from the northern North Atlantic is used to study hydrographic changes in surface water masses during the last 2000 years with a special focus on the Medieval Climate Anomaly (MCA) to the Little Ice Age (LIA) transition. Three of the cores are recovered from the sites located on main pathways of warm Atlantic water to the Arctic: M95-2011 (Vøring plateau, Norwegian Sea), Rapid-21 COM and LO-14 (Reykjanes Ridge, south of Iceland). The fourth core MD99-2322 is from the SE Greenland shelf (Denmark Strait), and it is influenced by the cold water outflow from the Arctic. The cores were analyzed continuously for planktonic diatoms with a high decadal to subdecadal temporal resolution. Past changes in the spatial distribution of surface water masses have been studied identifying factors, or typical species compositions, in downcore diatom assemblages. To derive the factors a Q-mode factor analysis has been applied to the extended modern calibration data set of 184 surface sediment samples from the North Atlantic, the Labrador Sea, the Nordic Seas, and Baffin Bay. SSTs have also been reconstructed using transfer functions. Variations of the reconstructed SSTs and loadings of major contributing factors reveal a complex regional pattern of changes in the structure of circulation during the MCA/LIA transition (1200-1400 AD). In the Norwegian Sea, the factors associated with assemblages typical for warmer and saline North Atlantic waters are partly displaced by colder and fresher water dwelling diatoms suggesting an eastward migration of mixed Arctic/Atlantic water masses into the Norwegian Sea. The two cores south of Iceland show a westward propagation of a warm water pulse as evidenced by the dominance of assemblages, which today are typical for the waters ca 5° further south than the current study sites. At the SE Greenland shelf an abrupt shift (ca. 50 years) in factors associated with different sea ice zone dwelling diatoms

  13. A modelling study of the influence of anomalous wind forcing over the Barents Sea on the Atlantic water flow to the Arctic Ocean in the period 1979-2004

    Science.gov (United States)

    Marciniak, Jakub; Schlichtholz, Pawel; Maslowski, Wieslaw

    2016-04-01

    Arctic climate system is influenced by oceanic heat transport with the Atlantic water (AW) streaming towards the Arctic Ocean in two branches, through the deep Fram Strait and the shallow Barents Sea. In Fram Strait, the AW submerges below the Polar surface water and then flows cyclonically along the margin of the Arctic Ocean as a subsurface water mass in the Arctic Slope Current. In contrast to the Fram Strait branch, which is the major source of heat for the Arctic Ocean, most of the heat influx to the Barents Sea through the Barents Sea opening (BSO) is passed to the atmosphere. Only cold remnants of AW outflow to the Arctic Ocean through the northeastern gate of the Barents Sea. Some AW entering the Barents Sea recirculates westward, contributing to an outflow from the Barents Sea through the BSO along the shelf slope south of Bear Island, in the Bear Island Slope Current. Even though the two-branched AW flow toward the Arctic Ocean has been known for more than a century, little is known about co-variability of heat fluxes in the two branches, its mechanisms and climatic implications. Recent studies indicate that the Bear Island Slope Current may play a role in this co-variability. Here, co-variability of the flow through the BSO and Fram Strait is investigated using a pan-Arctic coupled ice-ocean hindcast model run for the period 1979-2004 and forced with daily atmospheric data from the ECMWF. Significant wintertime co-variability between the volume transport in the Bear Island and Arctic slope currents and its link to wind forcing over the Barents Sea is confirmed. It is found that the volume transports in these currents are, however, not correlated in the annual mean and that the wintertime co-variability of these currents has no immediate effect on either the net heat flux through the BSO or the net heat flux divergence in the Barents Sea. It is shown that the main climatic effect of wind forcing over the northern Barents Sea shelf is to induce temperature

  14. Sex-structure, depth distribution, intermoult period and reproductive pattern of the deep-sea red crab Chaceon affinis (Brachyura, Geryonidae) in two populations in the north-eastern Atlantic

    Science.gov (United States)

    Biscoito, Manuel; Freitas, Mafalda; Pajuelo, José G.; Triay-Portella, Raül; Santana, José I.; Costa, Ana L.; Delgado, João; González, José A.

    2015-01-01

    This work investigated the biology of Chaceon affinis in two isolated populations of the Atlantic Ocean, including depth distribution, sexual structure, reproductive patterns and intermoult period. Males were larger and heavier than females. Mean size decreased with depth for both males and females. The highest abundance was found at 600-799 m of depth for males and at 800-999 m depth stratum for females. The highest abundance of ovigerous females was found at the 800-999 m depth stratum. Of the different ovaries' colour or colour shades recorded, only six categories were histologically characterized. The presence of spermatophores in the spermatheca of females in carapace stages II and III suggests that spermatophores are viable and used during the intermoult period. The size at sexual maturity in females was estimated at 104.4-104.7 mm carapace width (CW) in Madeira, and 109.3-110.5 mm CW in the Canary Islands. Only three categories of testes were identified. Mature testes consisted in a large mass, with highly coiled vasa deferentia visible to the naked eye. The size at sexual maturity in males was estimated at 113.8 mm CW in Madeira and 118.9 mm CW in the Canaries. The relative growth of males showed significant changes along the ontogeny and size at which allometric growth changes, as an indicator of morphometric maturity, occurred between 103.2 and 103.6 mm CW in Madeira and between 111.4 and 113.1 mm CW in the Canaries. In females, size at which allometric growth changes was found for maximum width of fifth abdominal somite (AS5W) at 98.2 mm CW in Madeira and 103.0 mm CW in the Canaries. The size at maturity obtained for C. affinis indicates that the minimum landing size (MLS) should not be set smaller than 125 mm CW in Madeira and 130 mm CW in the Canaries. This conservative MLS, higher than length at functional maturity, would safeguard immature individuals until they reach the size at which they can contribute to the reproductive capacity of the

  15. Blue whale (Balaenoptera musculus) sounds from the North Atlantic

    Science.gov (United States)

    Mellinger, David K.; Clark, Christopher W.

    2003-08-01

    Sounds of blue whales were recorded from U.S. Navy hydrophone arrays in the North Atlantic. The most common signals were long, patterned sequences of very-low-frequency sounds in the 15-20 Hz band. Sounds within a sequence were hierarchically organized into phrases consisting of one or two different sound types. Sequences were typically composed of two-part phrases repeated every 73 s: a constant-frequency tonal ``A'' part lasting approximately 8 s, followed 5 s later by a frequency-modulated ``B'' part lasting approximately 11 s. A common sequence variant consisted only of repetitions of part A. Sequences were separated by silent periods averaging just over four minutes. Two other sound types are described: a 2-5 s tone at 9 Hz, and a 5-7s inflected tone that swept up in frequency to ca. 70 Hz and then rapidly down to 25 Hz. The general characteristics of repeated sequences of simple combinations of long-duration, very-low-frequency sound units repeated every 1-2 min are typical of blue whale sounds recorded in other parts of the world. However, the specific frequency, duration, and repetition interval features of these North Atlantic sounds are different than those reported from other regions, lending further support to the notion that geographically separate blue whale populations have distinctive acoustic displays.

  16. Late Holocene climate change in the western Mediterranean: centennial-scale vegetation and North Atlantic Oscillation variability

    Science.gov (United States)

    Ramos Román, M. J.; Jimenez-Moreno, G.; Anderson, R. S.; García-Alix, A.; Toney, J. L.; Jiménez-Espejo, F. J. J.; Carrión, J. S.

    2015-12-01

    Sediments from alpine peat bogs and lakes from the Sierra Nevada in southeastern Spain (western Mediterranean area) have been very informative in terms of how vegetation and wetland environments were impacted by past climate change. Recently, many studies try to find out the relationship between solar activity, atmosphere and ocean dynamics and changes in the terrestrial environments. The Mediterranean is a very sensitive area with respect to atmospheric dynamics due to (1) its location, right in the boundary between subtropical and temperate climate systems and (2) the North Atlantic Oscillation (NAO) is one of the main mechanism that influence present climate in this area. Here we present a multi-proxy high-resolution study from Borreguil de la Caldera (BdlC), a peat bog that records the last ca. 4500 cal yr BP of vegetation, fire, human impact and climate history from the Sierra Nevada. The pollen, charcoal and non-pollen palynomorphs (NPPs) reconstruction in the BdlC-01 record evidence relative humidity changes in the last millennia interrupting the late Holocene aridification trend. This study shows a relative arid period between ca. 4000 and 3100 cal yr BP; the Iberian Roman humid period (ca. 2600 to 1600 cal yr BP); a relative arid period during the Dark Ages (from ca. AD 500 to AD 900) and Medieval Climate Anomaly (from ca. AD 900 to ca. AD 1300) and predominantly wetter conditions corresponding with The Little Ice Age period (from ca. AD 1300 to AD 1850). This climate variability could be explained by centennial scale changes in the NAO and solar activity.

  17. Rain rate statistics and fade distributions at 20 and 30 GHz derived from a network of rain gauges in the Mid-Atlantic coast over a five year period

    Science.gov (United States)

    Goldhirsh, Julius; Krichevsky, Vladimir; Gebo, Norman E.

    1992-01-01

    A network of ten tipping bucket rain gauges located within a grid 70 km north-south and 47 km east-west in the Mid-Atlantic coast of the United States was used to analyze rain rate and modeled slant path attenuation distributions at 20 and 30 GHz. It was shown that, for realistic fade margins at 20 GHz and above, the variable integration times results are adequate to estimate slant path attenuations using models which require 1 min averages. Crane's Global Model was used to derive fade distributions at 20 and 30 GHz.

  18. Climate Prediction Center (CPC) East Atlantic Teleconnection Pattern Index

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Monthly tabulated index of the East Atlantic Teleconnection pattern. The data spans the period 1950 to present. The index is derived from a rotated principal...

  19. Evidence of multidecadal climate variability and the Atlantic Multidecadal Oscillation from a Gulf of Mexico sea-surface temperature-proxy record

    Science.gov (United States)

    Poore, R.Z.; DeLong, K.L.; Richey, J.N.; Quinn, T.M.

    2009-01-01

    A comparison of a Mg/Ca-based sea-surface temperature (SST)-anomaly record from the northern Gulf of Mexico, a calculated index of variability in observed North Atlantic SST known as the Atlantic Multidecadal Oscillation (AMO), and a tree-ring reconstruction of the AMO contain similar patterns of variation over the last 110 years. Thus, the multidecadal variability observed in the instrumental record is present in the tree-ring and Mg/Ca proxy data. Frequency analysis of the Gulf of Mexico SST record and the tree-ring AMO reconstruction from 1550 to 1990 found similar multidecadal-scale periodicities (???30-60 years). This multidecadal periodicity is about half the observed (60-80 years) variability identified in the AMO for the 20th century. The historical records of hurricane landfalls reveal increased landfalls in the Gulf Coast region during time intervals when the AMO index is positive (warmer SST), and decreased landfalls when the AMO index is negative (cooler SST). Thus, we conclude that alternating intervals of high and low hurricane landfall occurrences may continue on multidecadal timescales along the northern Gulf Coast. However, given the short length of the instrumental record, the actual frequency and stability of the AMO are uncertain, and additional AMO proxy records are needed to establish the character of multidecadal-scale SST variability in the North Atlantic. ?? 2009 US Government.

  20. North Atlantic Temperature Anomaly

    OpenAIRE

    Vukcevic, M.A.

    2009-01-01

    The author postulates the existence of a high correlation between North Atlantic Temperature Anomaly and the variations of magnetic field over the Hudson Bay region. Post-glacial uplift and convection in the underlying mantle uplift (as reflected in changes of the area's magnetic intensity) are making significant contribution to the Atlantic basin climate change.

  1. On multidecadal and quasi-decadal North Atlantic variability

    OpenAIRE

    Alvarez-Garcia, F.; Latif, Mojib; Biastoch, Arne

    2008-01-01

    Observed sea surface temperatures (SSTs) in the North Atlantic from 1958 through 2000, as well as data from an ocean model simulation driven with the atmospheric variability observed during the same period, are examined using multichannel singular spectrum analysis. The two leading oscillatory modes are associated with a multidecadal and a quasi-decadal period. The former is connected to a basinwide uniform SST pattern and changes in the deep North Atlantic meridional overturning circulation....

  2. Periodic c-axis modulation and crystallographic Fourier analysis of Bi 2Sr 2Ca nCu n+1O 6+2n+x ( n=0,1) single crystals with excess Bi

    Science.gov (United States)

    Ariosa, D.; Berger, H.; Schmauder, T.; Pavuna, D.; Margaritondo, G.; Christensen, S.; Kelley, R. J.; Onellion, M.

    2001-04-01

    We report on a distortion of Bi 2Sr 2Ca nCu n+1O 6+2n+x ( n=0,1) single crystals, perpendicular to the CuO 2 planes (the c-axis), for non-stoichiometric samples containing an excess of Bi. The distortion involves two parts: (a) symmetric displacements in the SrO and CuO 2 planes along the c-axis, and (b) an antisymmetric longitudinal compressive wave. The latter is revealed by observing odd harmonics in the X-ray diffraction (XRD) data. Such odd harmonics are typically extinguished for the I4/mmm space group of the exact stoichiometric phase. The antisymmetric compressive wave is reported for both BSCCO-2201 and BSCCO-2212 Bi excess samples, as well as for La-doped BSCCO-2201 samples. We have performed XRD model calculations for all samples studied, combined with Fourier analysis of the periodic c-axis modulation. The antisymmetric compressive wave was proven by reconstructing the atomic position profile from the intensity of odd XRD peaks caused by this commensurate modulation. Our results indicate preferential ordered substitution of Bi ions on nominally Sr ion positions. We also discuss implications for oxygen mobility, reversible sample doping, and electronic properties.

  3. Catastrophic meltwater discharge down the Hudson Valley: a potential trigger for the Intra-Allerød cold period

    Science.gov (United States)

    Donnelly, Jeffrey P.; Driscoll, Neal W.; Uchupi, Elazar; Keigwin, Loyd D.; Schwab, William C.; Thieler, E. Robert; Swift, Stephen A.

    2005-01-01

    Glacial freshwater discharge to the Atlantic Ocean during deglaciation may have inhibited oceanic thermohaline circulation, and is often postulated to have driven climatic fluctuations. Yet attributing meltwater-discharge events to particular climate oscillations is problematic, because the location, timing, and amount of meltwater discharge are often poorly constrained. We present evidence from the Hudson Valley and the northeastern U.S. continental margin that establishes the timing of the catastrophic draining of Glacial Lake Iroquois, which breached the moraine dam at the Narrows in New York City, eroded glacial lake sediments in the Hudson Valley, and deposited large sediment lobes on the New York and New Jersey continental shelf ca. 13,350 yr B.P. Excess 14C in Cariaco Basin sediments indicates a slowing in thermohaline circulation and heat transport to the North Atlantic at that time, and both marine and terrestrial paleoclimate proxy records around the North Atlantic show a short-lived (<400 yr) cold event (Intra-Aller??d cold period) that began ca. 13,350 yr B.P. The meltwater discharge out the Hudson Valley may have played an important role in triggering the Intra-Aller??d cold period by diminishing thermohaline circulation. ?? 2005 Geological Society of America.

  4. A Low-Li Geochemical Province in the NE Atlantic

    DEFF Research Database (Denmark)

    Bailey, J. C.; Gwozdz, R.

    1978-01-01

    , over 20° of latitude and regardless of basalt type and chemistry. This low-Li province and the increasing Li contents of ocean-ridge tholeiites into the S Atlantic are believed to monitor Li heterogeneity in the underlying mantle. Li, like Na, increases gently during the differentiation of several......Lithium was analysed in 392 basalts and related igneous rocks from the North Atlantic Tertiary-Recent province using activation analysis and Čerenkov counting. Monotonous Li values of 5.5±2 ppm in NE Atlantic basalts define a low-Li geochemical province which has persisted for 60 million years...... basalt series. No whole-rock coherence is observed between Li and Mg, K, Rb or Ca. Mantle phlogopite is considered to play an insignificant rôle in controlling the Li levels of NE Atlantic basalts....

  5. SUBGLACIAL VOLCANO IN ATLANTIC

    OpenAIRE

    Nakamura, Shigehisa

    2010-01-01

    This is a note to satellite monitoring of the subglacial volcano in the Atlantic. The satellite data are obtained by EUMETSAT and NASA An eruption of a subglacial volcano in Iceland had issued volcanic ash, and the winds transferred the ash to the European Union in April 2010. This volcano is one of the volcanoes in the Atlantic. There are volcanoes in the north and south Atlantic. Some of them are in Azores Islands, in Canary Islands and Cape Verde Islands. Iceland is located on the zone of ...

  6. Similarities and dissimilarities between the last two deglaciations and interglaciations in the North Atlantic region

    Science.gov (United States)

    Martrat, Belen; Jimenez-Amat, Patricia; Zahn, Rainer; Grimalt, Joan O.

    2014-09-01

    Sea surface temperatures (SSTs) recorded by alkenones and oxygen isotopes in the Alboran basin are used here to describe, at an unprecedented fine temporal resolution, the present interglaciation (PIG, initiated at 11.7 ka BP), the last interglaciation (LIG, onset approximately at 129 ka) and respective deglaciations. Similarities and dissimilarities in the progression of these periods are reviewed in comparison with ice cores and stalagmites. Cold spells coeval with the Heinrich events (H) described in the North Atlantic include multi-decadal scale oscillations not previously obvious (up to 4 °C in less than eight centuries within the stadials associated with H1 and H11, ca 133 ka and 17 ka respectively). These abrupt oscillations precede the accumulation of organic rich layers deposited when perihelion moves from alignment with NH spring equinox to the summer solstice, a reference for deglaciations. Events observed during the last deglaciation at 17 ka, 14.8 ka and 11.7 ka are reminiscent of events occurred during the penultimate deglaciation at ca 136 ka, 132 ka and 129 ka, respectively. The SST trend during the PIG is no more than 2 °C (from 20 °C to 18 °C; up to -0.2 °C/ka). The trend is steeper during the LIG, i.e. up to a 5 °C change from the early interglaciation to immediately before the glacial inception (from 23 °C to 18 °C; up to -0.4 °C/ka). Events are superimposed upon a long term trend towards colder SSTs, beginning with SST maxima followed by temperate periods until perihelion aligned with the NH autumn equinox (before ca 5.3 ka for the PIG and 121 ka for the LIG). A cold spell of around eight centuries at 2.8 ka during the PIG was possibly mimicked during the LIG at ca 118 ka by a SST fall of around 1 °C in a millennium. These events led interglacial SST to stabilise at around 18 °C. The glacial inception, barely evident at the beginning ca 115 ka (North Atlantic event C25, after perihelion passage in the NH winter solstice), culminated

  7. Atlantic Salmon Telemetry Monitoring

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Annual telemetry data are collected as part of specific projects (assessments within watersheds) or as opportunistic efforts to characterize Atlantic salmon smolt...

  8. Woman Swims Atlantic

    Institute of Scientific and Technical Information of China (English)

    贾庆文

    2009-01-01

    Jennifer Figge pressed her toes into the Caribbean sand, excited and exhausted as she touched land this week for the first time in almost a month. Reaching a beach in Trinidad, she became the first woman on record to s,Mm across the Atlantic Ocean-a dream she'd had since the early 1960s, when a stormy trans-Atlantic flight got her thinking she could wear a life vest and swim the rest of the way if needed.

  9. Early Holocene variability in the Arctic Gateway - High-resolution records reflecting Atlantic Water advection and ice coverage

    Science.gov (United States)

    Spielhagen, Robert F.; Bauch, Henning A.; Maudrich, Martin; Not, Christelle; Telesinski, Maciej M.; Werner, Kirstin

    2015-04-01

    The Arctic Gateway between Greenland and Svalbard is the main passage for the advection of Atlantic Water to the Arctic Ocean. Water temperature and intensity of this advection largely determine the degree of ice coverage which is fed by sea ice export from the north. Supported by a maximum in insolation, the Early Holocene was a period of extraordinarily strong advection and relatively high near-surface water temperatures in the eastern Nordic Seas (cf. Risebrobakken et al., 2011, Paleoceanography v. 26). Here we present a synthesis of radiocarbon-dated records from the northern and western part of this area, reaching from the SW Greenland Sea (73°N) to the Yermak Plateau (81°N) and revealing temporal and spatial differences in the development of the so-called Holocene Thermal Maximum (HTM). In the northern part of this region, the HTM started ca. 11-10.5 ka as indicated by rapidly increasing amounts of subpolar planktic foraminifers in the sediments. In the eastern Fram Strait and on the Yermak Plateau, our records of (sub)millennial scale resolution show that the maximum influx terminated already 2,000 years later (9-8 ka). Most likely, this development went along with a N-S relocation of the sea ice margin. According to the current stratigraphic model for a core with submillennial-scale resolution from Vesterisbanken seamount (73°N) in the Greenland Sea, the timing was different there. Increasing total amounts of planktic foraminifers in the sediment indicate an early (11-10 ka) reduction in sea ice coverage also in this region. However, evidence from subpolar planktic foraminifers for maximum Atlantic Water advection is younger (9-6 ka) than in the north. Apparently, the site in the SW Greenland Sea was affected by Atlantic Water in the Greenland Gyre that decoupled from the northward flowing Norwegian Atlantic Current/Westspitsbergen Current south of the Fram Strait. Thus, in a suite of events, strong Atlantic Water advection first affected the

  10. 75 FR 10450 - Fisheries of the Northeastern United States; Atlantic Bluefish Fisheries; 2010 Atlantic Bluefish...

    Science.gov (United States)

    2010-03-08

    ...). Alternative 3, the no action alternative, is considered to be synonymous with status quo management measures... a given phase in the rebuilding period, or the status quo F, whichever is less. According to... alternatives (including a no action/status quo alternative) for 2010 Atlantic bluefish fishery. All...

  11. Glacial climate sensitivity to different states of the Atlantic Meridional overturning circulation : results from the IPSL model

    OpenAIRE

    Kageyama, M.; J. Mignot; D. Swingedouw; Marzin, C.; Alkama, R.; O. Marti

    2009-01-01

    Numerous records from the North Atlantic and the surrounding continents have shown rapid and large amplitude climate variability during the last glacial period. This variability has often been associated to changes in the Atlantic Meridional Overturning Circulation (AMOC). Rapid climate change on the same time scales has also been reconstructed for sites far away from the North Atlantic, such as the tropical Atlantic, the East Pacific and Asia. The mechanisms explaining these climatic respons...

  12. The diagnostic value of joint detection of serum CA19-9, CA125 and CA242 for cholangiocarcinoma

    Institute of Scientific and Technical Information of China (English)

    Cui Da-Peng; Han Lei; Liu Zhen-Xian; Yang He; Zhang Ying-Chun

    2016-01-01

    Objective:To study the diagnostic value of joint detection of serum CA19-9, CA125 and CA242 for cholangiocarcinoma.Methods:A total of 35 patients with cholangiocarcinoma who received surgical resection in our hospital were selected as malignant group, 30 patients with cholelithiasis who received surgical resection in our hospital during the same period were selected as benign group, serum samples were collected before surgery to determine CA19-9, CA125 and CA242 content, and cholangiocarcinoma tissue and normal bile duct tissue were collected after surgery to determine the content of proliferation and invasion molecules. Results:Serum CA19-9, CA125 and CA242 levels of malignant group were significantly higher than those of control group; PROX-1, Ki-67, Bcl-2, Bad, Gab1, LOXL2, TRPM7 and CXCL12 levels in cholangiocarcinoma tissue were higher than those in benign bile duct tissue, and E-cadherin level was lower than that in benign bile duct tissue; serum CA19-9, CA125 and CA242 levels were positively correlated with PROX-1, Ki-67, Bcl-2, Bad, Gab1, LOXL2, TRPM7 and CXCL12 levels, and negatively correlated with E-cadherin level.Conclusion:Joint detection of serum CA19-9, CA125 and CA242 can not only provide reference for the diagnosis of cholangiocarcinoma, but can also provide basis for the evaluation of proliferation, invasion and other malignant biological behaviors.

  13. North Atlantic Circulation

    Science.gov (United States)

    Molinari, R.; Bryan, K.; Schott, F.

    The intensity of the North Atlantic winddriven and thermohaline circulation and the close proximity of many oceanographic installations make the North Atlantic a particularly favored region of the world ocean from the standpoint of research in ocean circulation. Recent increases in available data and advances in numerical modeling techniques served as the impetus to convene a joint workshop of modelers and observers working on the North Atlantic with the Scientific Committee on Oceanic Research (SCOR) Working Group (WG) 68 (“North Atlantic Circulation”). Goals of the workshop were to provide an update on data sets and models and to discuss the poleward heat flux problem and possible monitoring strategies. The joint Workshop/SCOR WG-68 meeting was convened by F. Schott (chairman of the working group; Rosenstiel School of Marine and Atmospheric Science, Miami, Fla.), K. Bryan (National Oceanic and Atmospheric Administration/ Geophysical Fluid Dynamics Laboratory (NOAA/GFDL)), and R. Molinari (NOAA/Atlantic Oceanographic and Meteorological Laboratory (NOAA/AOML)).

  14. Atlantic menhaden adult tagging study

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Atlantic menhaden are a schooling forage fish species, which are subject to a large commercial purse seine fishery. Atlantic menhaden are harvested for reduction...

  15. Coccolithophore surface distributions in the North Atlantic and their modulation of the air-sea flux of CO2 from 10 years of satellite Earth observation data

    Directory of Open Access Journals (Sweden)

    J. D. Shutler

    2013-04-01

    Full Text Available Coccolithophores are the primary oceanic phytoplankton responsible for the production of calcium carbonate (CaCO3. These climatically important plankton play a key role in the oceanic carbon cycle as a major contributor of carbon to the open ocean carbonate pump (~50% and their calcification can affect the atmosphere-to-ocean (air-sea uptake of carbon dioxide (CO2 through increasing the seawater partial pressure of CO2 (pCO2. Here we document variations in the areal extent of surface blooms of the globally important coccolithophore, Emiliania huxleyi, in the North Atlantic over a 10-year period (1998–2007, using Earth observation data from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS. We calculate the annual mean sea surface areal coverage of E. huxleyi in the North Atlantic to be 474 000 ± 104 000 km2, which results in a net CaCO3 carbon (CaCO3-C production of 0.14–1.71 Tg CaCO3-C per year. However, this surface coverage (and, thus, net production can fluctuate inter-annually by −54/+8% about the mean value and is strongly correlated with the El Niño/Southern Oscillation (ENSO climate oscillation index (r=0.75, pE. huxleyi blooms in the North Atlantic can increase the pCO2 and, thus, decrease the localised air-sea flux of atmospheric CO2. In regions where the blooms are prevalent, the average reduction in the monthly air-sea CO2 flux can reach 55%. The maximum reduction of the monthly air-sea CO2 flux in the time series is 155%. This work suggests that the high variability, frequency and distribution of these calcifying plankton and their impact on pCO2 should be considered if we are to fully understand the variability of the North Atlantic air-to-sea flux of CO2. We estimate that these blooms can reduce the annual N. Atlantic net sink atmospheric CO2 by between 3–28%.

  16. Low energy 40Ca + 40Ca collisions

    International Nuclear Information System (INIS)

    This paper deals with the classical microscopic study of 40Ca + 40Ca collisions. Fusion cross-sections (σsub(CF)) for various incident energies, energy variations with time, shape deformation and the life time of resonance scattering (T) have been studied. Comparison of 40Ca + 40Ca results with those of 16O + 16O have also been made. (author)

  17. Ca2+ Alternans in a Cardiac Myocyte Model that Uses Moment Equations to Represent Heterogeneous Junctional SR Ca2+

    OpenAIRE

    Huertas, Marco A; Smith, Gregory D.; Györke, Sándor

    2010-01-01

    Multiscale whole-cell models that accurately represent local control of Ca2+-induced Ca2+ release in cardiac myocytes can reproduce high-gain Ca2+ release that is graded with changes in membrane potential. Using a recently introduced formalism that represents heterogeneous local Ca2+ using moment equations, we present a model of cardiac myocyte Ca2+ cycling that exhibits alternating sarcoplasmic reticulum (SR) Ca2+ release when periodically stimulated by depolarizing voltage pulses. The model...

  18. Heterogeneous oxygenation states in the Atlantic and Tethys oceans during Oceanic Anoxic Event 2

    Science.gov (United States)

    Westermann, Stéphane; Vance, Derek; Cameron, Vyllinniskii; Archer, Corey; Robinson, Stuart A.

    2014-10-01

    The Cenomanian-Turonian boundary (ca. 93.5 Ma) is marked by an episode of profound environmental change, including a major perturbation of the carbon cycle and an Oceanic Anoxic Event (OAE-2). Here, we present molybdenum (Mo) isotope variations within the OAE-2 interval for four sections from the western Tethys (Furlo and La Contessa) and the North-Atlantic (ODP site 1276 and DSDP site 367). The main target of this study is to investigate the extent of reducing conditions (truly global in extent or restricted to poorly-ventilated restricted deep basins), with particular reference to the relationship between the change in the oxygenation state of the ocean and the link to global perturbations of the carbon cycle recorded in carbon isotopes. All four sections show fluctuations in the redox sensitive trace metal (RSTE) distribution, suggesting rapid variations in local redox conditions, ranging from anoxic to euxinic. The RSTE enrichment factors (EFs) also suggest different depositional conditions and paleoceanographic processes in the western Tethys versus the North Atlantic. Whereas the North Atlantic sites show evidence of weak watermass restriction associated with the action of a particulate shuttle within the water column, the EFs of the Tethyan sections are characteristic of unrestricted marine systems. Mo isotopes show surprisingly negative values through the Tethyan sections. At the onset of OAE-2, an increasing trend in δMo98 is observed, with values ranging from -0.6 to 0.6‰. During the second half of OAE-2, the δMo98 curve shows a progressive shift towards more negative values. In the North Atlantic, δMo98 signatures from ODP site 1276 show a similar behaviour as observed in the western Tethys. At DSDP site 367, Mo isotopes are generally heavier during OAE-2, fluctuating around an average value of 1.1‰. This is consistent with fully euxinic conditions and the black shales deposited may have recorded the seawater signature during OAE-2. The Mo isotope

  19. Surface heat storage in the subtropical North Atlantic during the LGM

    Science.gov (United States)

    Repschlaeger, Janne; Weinelt, Mara; Garbe-Schönberg, Dieter; Andersen, Nils; Schneider, Ralph

    2016-04-01

    The transport of warm saline waters from the subtropical into the subpolar North Atlantic plays a major role in the stabilization of AMOC. During the Late Pleistocene this system experienced millennial scale variability with weak AMOC phases that are associated with heat and salt storage within the subtropics. The subsequent onset of AMOC is supposed to be fueled by the release and transport of the warm saline water into the northern hemisphere deepwater convection sites. Despite this conceptual model, contradicting reconstructions for such warm water storage exist for the Deglaciation to early Holocene and full glacial periods, either asserting a southward movement of the Subtropical gyre (STG) and subsurface heat storage or northward extension of the STG with warming of the surface waters. Here we investigate the heat and salt storage patterns and extension of the warm subtropical gyre (STG) during MIS 2 well into MIS 3 (16- 30 ka BP) at centennial scale resolution using sediment core MD08-3181 (38°N; 31.13°W, 3060 m w.d.) retrieved immediately east of the Mid Atlantic Ridge south of the Azores Islands with sedimentation rates up to 100 cm/ ka. At present, this site is located at the northern rim of the Azores Current, which delineates the STG, recirculating warm waters of the North Atlantic Current. Due to its position at the boundary between temperate Northeast Atlantic waters and warm STG waters, the coring site is ideal to trace past changes in the influence of both water masses. Parallel stable-oxygen isotope and Mg/Ca temperature records of surface-water dwelling foraminifera Globigerina bulloides (habitat depth 0-200 m) and subsurface dweller Globorotalia inflata (habitat depth 100-300 m) and foraminiferal transfer functions are used to reconstruct the temperature and salinity structure of the mixed layer. Additionally, the AF position is reconstructed using the abundance of the tropical to subtropical species Globigerinoides ruber white. Preliminary

  20. Atlantic City memories.

    Science.gov (United States)

    Epstein, Franklin H

    2008-04-01

    Fifty years ago, the Atlantic City meetings, held the first week in May of every year, were attended by all the elite of American academic medicine and all who wanted to join that group. Part of the magic of those meetings was that professors and neophytes took each other seriously and talked to each other. PMID:18382726

  1. Fine tuning of cytosolic Ca 2+ oscillations

    Science.gov (United States)

    Dupont, Geneviève; Combettes, Laurent

    2016-01-01

    Ca 2+ oscillations, a widespread mode of cell signaling, were reported in non-excitable cells for the first time more than 25 years ago. Their fundamental mechanism, based on the periodic Ca 2+ exchange between the endoplasmic reticulum and the cytoplasm, has been well characterized. However, how the kinetics of cytosolic Ca 2+ changes are related to the extent of a physiological response remains poorly understood. Here, we review data suggesting that the downstream targets of Ca 2+ are controlled not only by the frequency of Ca 2+ oscillations but also by the detailed characteristics of the oscillations, such as their duration, shape, or baseline level. Involvement of non-endoplasmic reticulum Ca 2+ stores, mainly mitochondria and the extracellular medium, participates in this fine tuning of Ca 2+ oscillations. The main characteristics of the Ca 2+ exchange fluxes with these compartments are also reviewed. PMID:27630768

  2. Sudden intrusion of corrosive bottom water into the South Atlantic during the Paleocene-Eocene Thermal Maximum

    Science.gov (United States)

    Meissner, K. J.; Alexander, K.; Bralower, T. J.

    2015-12-01

    The Paleocene-Eocene Thermal Maximum, ˜55 million years before present, was a period of rapid warming marked by a negative carbon isotope excursion and widespread dissolution of seafloor carbonate. These changes have been attributed to a massive release of carbon into the exogenic carbon cycle, and thus, the event provides an analog for future climate and environmental changes given the current anthropogenic CO2 emissions. Previous attempts to constrain the amount of carbon released have produced widely diverging results, between 2000 and 10,000 gigatons carbon (GtC). Sediment records indicate that acidification of deep waters was generally more extensive and severe in the Atlantic and Caribbean regions, with more modest changes in the Southern and Pacific Oceans. Here we compare simulations integrated with the UVic Earth System Climate Model with reconstructions of temperature and dissolution to present a mechanism that might explain the observed spatial differences and to constrain the total mass of carbon released. Due to the late Paleocene topography, highly corrosive waters accumulate in the deep North Atlantic before the PETM in our simulations. Several thousand years into the event, deep ocean warming destabilizes the North Atlantic water column and triggers deep water formation. This causes the corrosive bottom water to spill over an equatorial sill into the South Atlantic and through the Southern and Pacific Oceans, progressively gaining alkalinity. The simulated pattern of sediment dissolution along the path taken by this corrosive water is consistent with most dissolution estimates made from CaCO3 measurements in the Paleocene-Eocene sediment record. We find two scenarios that agree best with proxy data: a carbon release of 7000 GtC in combination with pre-event atmospheric carbon dioxide concentrations of 840 ppm and a carbon release of 7000-10,000 GtC with pre-event CO2 concentrations of 1680 ppm.

  3. North Atlantic SST anomalies and the cold North European weather events of winter 2009/10 and December 2010

    OpenAIRE

    Buchan, Jian; Hirschi, Joel; Blaker, Adam; Sinha, Bablu

    2014-01-01

    Northern Europe experienced consecutive periods of extreme cold weather in the winter of 2009/2010 and in late 2010. These periods were characterised by a tripole pattern in North Atlantic sea surface temperature (SST) anomalies and exceptionally negative phases of the North Atlantic Oscillation (NAO). A global Ocean-Atmosphere General Circulation Model (OAGCM) is used to investigate the ocean’s role in influencing North Atlantic and European climate. Observed SST anomalies are used to force ...

  4. 75 FR 44938 - Atlantic Coastal Fisheries Cooperative Management Act Provisions; Atlantic Coastal Shark Fishery

    Science.gov (United States)

    2010-07-30

    ... National Oceanic and Atmospheric Administration RIN 0648-XX28 Atlantic Coastal Fisheries Cooperative Management Act Provisions; Atlantic Coastal Shark Fishery AGENCY: National Marine Fisheries Service (NMFS... Atlantic Coastal Fisheries Cooperative Management Act (Atlantic Coastal Act), based on the...

  5. Evolution of South Atlantic density and chemical stratification across the last deglaciation.

    Science.gov (United States)

    Roberts, Jenny; Gottschalk, Julia; Skinner, Luke C; Peck, Victoria L; Kender, Sev; Elderfield, Henry; Waelbroeck, Claire; Vázquez Riveiros, Natalia; Hodell, David A

    2016-01-19

    Explanations of the glacial-interglacial variations in atmospheric pCO2 invoke a significant role for the deep ocean in the storage of CO2. Deep-ocean density stratification has been proposed as a mechanism to promote the storage of CO2 in the deep ocean during glacial times. A wealth of proxy data supports the presence of a "chemical divide" between intermediate and deep water in the glacial Atlantic Ocean, which indirectly points to an increase in deep-ocean density stratification. However, direct observational evidence of changes in the primary controls of ocean density stratification, i.e., temperature and salinity, remain scarce. Here, we use Mg/Ca-derived seawater temperature and salinity estimates determined from temperature-corrected δ(18)O measurements on the benthic foraminifer Uvigerina spp. from deep and intermediate water-depth marine sediment cores to reconstruct the changes in density of sub-Antarctic South Atlantic water masses over the last deglaciation (i.e., 22-2 ka before present). We find that a major breakdown in the physical density stratification significantly lags the breakdown of the deep-intermediate chemical divide, as indicated by the chemical tracers of benthic foraminifer δ(13)C and foraminifer/coral (14)C. Our results indicate that chemical destratification likely resulted in the first rise in atmospheric pCO2, whereas the density destratification of the deep South Atlantic lags the second rise in atmospheric pCO2 during the late deglacial period. Our findings emphasize that the physical and chemical destratification of the ocean are not as tightly coupled as generally assumed.

  6. Distribution and at-sea activity of a nocturnal seabird, the Bulwer's petrel Bulweria bulwerii, during the incubation period

    Science.gov (United States)

    Dias, Maria P.; Romero, Joana; Granadeiro, José Pedro; Catry, Teresa; Pollet, Ingrid L.; Catry, Paulo

    2016-07-01

    Bulwer's petrels are nocturnal seabirds that mostly prey on mesopelagic fauna. As aerial foragers and shallow divers, their feeding opportunities are limited by near-surface availability of their prey, which is highly variable both temporally (reflecting diurnal and lunar cycles) and spatially. Here we studied how Bulwer's petrels cope with these constraints by analysing their at-sea distribution and activity during the incubation period. We tracked the movements of 20 birds from Selvagem Grande (NE Atlantic) during a complete lunar cycle, and recorded 30 foraging trips that lasted 11 days on average. Birds were both distributed around the colony and in waters close to the Azorean archipelago (mid-Atlantic) located 1700 km away, and were significantly more active at night (especially just after sunset and before sunrise), when mesopelagic fauna is also closer to the sea surface due to their diel vertical migrations. Bulwer's petrels spent significantly more time flying during moonlight, although the effect of the moon was relatively weak (ca. 10-15% difference between moonlit and dark periods of the night), and not obvious when birds were foraging in mid-Atlantic waters, which were also targeted more often during full-moon. These results reveal key adaptations of the Bulwer's petrel to the highly dynamic ecology of its mesopelagic prey.

  7. In Brief: Atlantic seasonal hurricane forecast

    Science.gov (United States)

    Showstack, Randy

    2007-12-01

    Two hurricane forecasters are predicting that 2008 will be an above-average Atlantic basin tropical cyclone season with an above-average probability of a major hurricane making landfall in the United States. During 2008, there could be about seven hurricanes (the annual average is 5.9) and 13 named storms (the average is 9.6), according to a 7 December report by Philip Klotzbach, research scientist at Colorado State University in Fort Collins, and William Gray, university professor emeritus of atmospheric sciences. The forecasters indicate that they believe the Atlantic basin is in an active hurricane cycle that is associated with a strong thermohaline circulation and an active phase of the Atlantic Multidecadal Oscillation. The report notes that, ``real-time operational early December forecasts have not shown forecast skill over climatology during this 16-year period [1992-2007]. This has occurred despite the fact that the skill over the hindcast period...showed appreciable skill.'' For more information, visit the Web site: http://hurricane.atmos.colostate.edu/Forecasts/2007/dec2007/dec2007.pdf.

  8. Tropical Pacific/Atlantic Ocean interactions at multi‐decadal time scales

    OpenAIRE

    Latif, Mojib

    2001-01-01

    Analysis of sea surface temperature (SST) observations suggests a pan‐oceanic interaction between the tropical Pacific and the Atlantic Ocean at multi‐decadal time scales, such that periods of anomalously high SSTs in the tropical Pacific are followed by a basin‐wide SST dipole in the Atlantic Ocean with a time delay of a few decades. The SST anomaly structure in the Atlantic Ocean is reminscent of variations in the North Atlantic thermohaline circulation. The two ocean basins are linked thro...

  9. Periodic Mesoporous Organosilica Nanorice

    Directory of Open Access Journals (Sweden)

    Mohanty Paritosh

    2008-01-01

    Full Text Available Abstract A periodic mesoporous organosilica (PMO with nanorice morphology was successfully synthesized by a template assisted sol–gel method using a chain-type precursor. The PMO is composed of D and T sites in the ratio 1:2. The obtained mesoporous nanorice has a surface area of 753 m2 g−1, one-dimensional channels, and a narrow pore size distribution centered at 4.3 nm. The nanorice particles have a length of ca. 600 nm and width of ca. 200 nm.

  10. Potential tropical Atlantic impacts on Pacific decadal climate trends

    Science.gov (United States)

    Chikamoto, Y.; Mochizuki, T.; Timmermann, A.; Kimoto, M.; Watanabe, M.

    2016-07-01

    The tropical Pacific cooling from the early 1990s to 2013 has contributed to the slowdown of globally averaged sea surface temperatures (SSTs). The origin of this regional cooling trend still remains elusive. Here we demonstrate that the remote impact of Atlantic SST anomalies, as well as local atmosphere-ocean interactions, contributed to the eastern Pacific cooling during this period. By assimilating observed three-dimensional Atlantic temperature and salinity anomalies into a coupled general circulation model, we are able to qualitatively reproduce the observed Pacific decadal trends of SST and sea level pressure (SLP), albeit with reduced amplitude. Although a major part of the Pacific SLP trend can be explained by equatorial Pacific SST forcing only, the origin of this low-frequency variability can be traced back further to the remote impacts of equatorial Atlantic and South Atlantic SST trends. Atlantic SST impacts on the atmospheric circulation can also be detected for the Northeastern Pacific, thus providing a linkage between Atlantic climate and Western North American drought conditions.

  11. 77 FR 41728 - Plan for Periodic Review of Regulations

    Science.gov (United States)

    2012-07-16

    .... Atlantic Coastal Fisheries Cooperative Management Act Provisions; Fisheries of the Northeastern United... for Periodic Review of Regulations AGENCY: National Marine Fisheries Service (NMFS), National Oceanic...: The Regulatory Flexibility Act (RFA) requires that the National Marine Fisheries Service...

  12. Two Distinct Roles of Atlantic SSTs in ENSO Variability: North Tropical Atlantic SST and Atlantic Nino

    Science.gov (United States)

    Ham, Yoo-Geun; Kug, Jong-Seong; Park, Jong-Yeon

    2013-01-01

    Two distinct roles of the Atlantic sea surface temperatures (SSTs), namely, the North Tropical Atlantic (NTA) SST and the Atlantic Nino, on the El Nino-Southern Oscillation (ENSO) variability are investigated using the observational data from 1980 to 2010 and coupled model experiments. It appears that the NTA SST and the Atlantic Nino can be used as two independent predictors for predicting the development of ENSO events in the following season. Furthermore, they are likely to be linked to different types of El Nino events. Specifically, the NTA SST cooling during February, March, and April contributes to the central Pacific warming at the subsequent winter season, while the negative Atlantic Nino event during June, July, and August contributes to enhancing the eastern Pacific warming. The coupled model experiments support these results. With the aid of a lagged inverse relationship, the statistical forecast using two Atlantic indices can successfully predict various ENSO indices.

  13. Periodic functions with variable period

    OpenAIRE

    Pryjmak, M. V

    2010-01-01

    The examples of rhythmical signals with variable period are considered. The definition of periodic function with the variable period is given as a model of such signals. The examples of such functions are given and their variable periods are written in the explicit form. The system of trigonometric functions with the variable period is considered and its orthogonality is proved. The generalized system of trigonometric functions with the variable period is also suggested; some conditions of it...

  14. An electrical analogy relating the Atlantic multidecadal oscillation to the Atlantic meridional overturning circulation.

    Directory of Open Access Journals (Sweden)

    Bruce E Kurtz

    Full Text Available The Atlantic meridional overturning circulation (AMOC is the northward flow of surface water to subpolar latitudes where deepwater is formed, balanced by southward abyssal flow and upwelling in the vicinity of the Southern Ocean. It is generally accepted that AMOC flow oscillates with a period of 60-80 years, creating a regular variation in North Atlantic sea surface temperature known as the Atlantic multidecadal oscillation (AMO. This article attempts to answer two questions: how is the AMOC driven and why does it oscillate? Using methods commonly employed by chemical engineers for analyzing processes involving flowing liquids, apparently not previously applied to trying to understand the AMOC, an equation is developed for AMOC flow as a function of the meridional density gradient or the corresponding temperature gradient. The equation is based on the similarity between the AMOC and an industrial thermosyphon loop cooler, which circulates a heat transfer liquid without using a mechanical pump. Extending this equation with an analogy between the flow of heat and electricity explains why the AMOC flow oscillates and what determines its period. Calculated values for AMOC flow and AMO oscillation period are in good agreement with measured values.

  15. Marine ecosystem response to the Atlantic Multidecadal Oscillation.

    Directory of Open Access Journals (Sweden)

    Martin Edwards

    Full Text Available Against the backdrop of warming of the Northern Hemisphere it has recently been acknowledged that North Atlantic temperature changes undergo considerable variability over multidecadal periods. The leading component of natural low-frequency temperature variability has been termed the Atlantic Multidecadal Oscillation (AMO. Presently, correlative studies on the biological impact of the AMO on marine ecosystems over the duration of a whole AMO cycle (∼60 years is largely unknown due to the rarity of continuously sustained biological observations at the same time period. To test whether there is multidecadal cyclic behaviour in biological time-series in the North Atlantic we used one of the world's longest continuously sustained marine biological time-series in oceanic waters, long-term fisheries data and historical records over the last century and beyond. Our findings suggest that the AMO is far from a trivial presence against the backdrop of continued temperature warming in the North Atlantic and accounts for the second most important macro-trend in North Atlantic plankton records; responsible for habitat switching (abrupt ecosystem/regime shifts over multidecadal scales and influences the fortunes of various fisheries over many centuries.

  16. Recent Changes in Arctic Ocean Sea Ice Motion Associated with the North Atlantic Oscillation

    Science.gov (United States)

    Kwok, R.

    1999-01-01

    Examination of a new ice motion dataset of the Arctic Ocean over a recent eighteen year period (1978-1996) reveals patterns of variability that can be linked directly to the North Atlantic Oscillation.

  17. Climate Prediction Center (CPC) Monthly North Atlantic Oscillation (NAO) teleconnection index

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Monthly tabulated index of the North Atlantic Oscillation (NAO) teleconnection pattern. The data spans the period 1950 to present. The index is derived from a...

  18. Climate Prediction Center (CPC) East Atlantic/ Western Russia Teleconnection Pattern Index

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Monthly tabulated index of the East Atlantic/ Western Russia teleconnection pattern. The data spans the period 1950 to present. The index is derived from a rotated...

  19. Mid-Atlantic Regional Wind Energy Institute

    Energy Technology Data Exchange (ETDEWEB)

    Courtney Lane

    2011-12-20

    As the Department of Energy stated in its 20% Wind Energy by 2030 report, there will need to be enhanced outreach efforts on a national, state, regional, and local level to communicate wind development opportunities, benefits and challenges to a diverse set of stakeholders. To help address this need, PennFuture was awarded funding to create the Mid-Atlantic Regional Wind Energy Institute to provide general education and outreach on wind energy development across Maryland, Virginia, Delaware, Pennsylvania and West Virginia. Over the course of the two-year grant period, PennFuture used its expertise on wind energy policy and development in Pennsylvania and expanded it to other states in the Mid-Atlantic region. PennFuture accomplished this through reaching out and establishing connections with policy makers, local environmental groups, health and economic development organizations, and educational institutions and wind energy developers throughout the Mid-Atlantic region. PennFuture conducted two regional wind educational forums that brought together wind industry representatives and public interest organizations from across the region to discuss and address wind development in the Mid-Atlantic region. PennFuture developed the agenda and speakers in collaboration with experts on the ground in each state to help determine the critical issue to wind energy in each location. The sessions focused on topics ranging from the basics of wind development; model ordinance and tax issues; anti-wind arguments and counter points; wildlife issues and coalition building. In addition to in-person events, PennFuture held three webinars on (1) Generating Jobs with Wind Energy; (2) Reviving American Manufacturing with Wind Power; and (3) Wind and Transmission. PennFuture also created a web page for the institute (http://www.midatlanticwind.org) that contains an online database of fact sheets, research reports, sample advocacy letters, top anti-wind claims and information on how to

  20. Calcium distribution in the subtropical Atlantic Ocean: Implications for calcium excess and saturation horizons

    Science.gov (United States)

    Rosón, Gabriel; Guallart, Elisa F.; Pérez, Fiz F.; Ríos, Aida F.

    2016-06-01

    This study constituted the first attempt to measure dissolved calcium ([Ca2 +]meas) in the subtropical North Atlantic, during a zonal transoceanic cruise along 24.5°N (WOCE A05 section), in summer 1992. [Ca2 +]meas was obtained in 20 full-depth equidistant stations along the section, showing that their gradients are rather sensitive to horizontal and vertical water mass distribution. Deep waters along 24.5°N systematically show a positive calcium excess of 20 ± 14 μmol·kg- 1, i.e., more [Ca2 +] than expected by CaCO3 dissolution and organic matter oxidation (estimated by total alkalinity and nitrate). CaCO3 settling and benthic dissolution accounts for 70% and the North Atlantic plus Arctic riverine inputs of HCO3- for the remaining 30%. Combining [Ca2 +]meas and CO2 data sets, carbonate mineral saturation states distributions for aragonite and calcite can be obtained. The two solubility ratios resulted, on average, 0.5% smaller than if conservative behavior for Ca2 + was assumed (an approach widely followed when [Ca2 +]meas is unknown). As a result, shallower saturation horizon depths for both carbonate states (19 dbar for aragonite and 10 dbar for calcite) are yielded if [Ca2 +]meas is taken into account instead than estimated from salinity.

  1. Relation between the wind stress curl in the North Atlantic and the Atlantic inflow to the Nordic Seas

    OpenAIRE

    Sandø, Anne Britt; Furevik, Tore

    2008-01-01

    In this study an isopycnic coordinate ocean model has been used to investigate the relationships between the North Atlantic wind stress curl (WSC) and the inflow of Atlantic water to the Nordic Seas. For the period 1995–2001, there is a maximum in the correlation between the zonally averaged WSC at 55!N and the inflow with a 15-month time lag, capturing a relation already found in observational data. In the model this relation is linked to the mixing along the western flank of the...

  2. Sequestration of carbon in the deep Atlantic during the last glaciation

    Science.gov (United States)

    Yu, J.; Menviel, L.; Jin, Z. D.; Thornalley, D. J. R.; Barker, S.; Marino, G.; Rohling, E. J.; Cai, Y.; Zhang, F.; Wang, X.; Dai, Y.; Chen, P.; Broecker, W. S.

    2016-04-01

    Atmospheric CO2 concentrations declined markedly about 70,000 years ago, when the Earth’s climate descended into the last glaciation. Much of the carbon removed from the atmosphere has been suspected to have entered the deep oceans, but evidence for increased carbon storage remains elusive. Here we use the B/Ca ratios of benthic foraminifera from several sites across the Atlantic Ocean to reconstruct changes in the carbonate ion concentration and hence the carbon inventory of the deep Atlantic across this transition. We find that deep Atlantic carbonate ion concentration declined by around 25 μmol kg-1 between ~80,000 and 65,000 years ago. This drop implies that the deep Atlantic carbon inventory increased by at least 50 Gt around the same time as the amount of atmospheric carbon dropped by about 60 Gt. From a comparison with proxy records of deep circulation and climate model simulations, we infer that the carbon sequestration coincided with a shoaling of the Atlantic meridional overturning circulation. We thus conclude that changes in the Atlantic Ocean circulation may have played an important role in reductions of atmospheric CO2 concentrations during the last glaciation, by increasing the carbon storage in the deep Atlantic.

  3. 75 FR 22103 - Atlantic Coastal Fisheries Cooperative Management Act Provisions; Atlantic Coastal Shark Fishery

    Science.gov (United States)

    2010-04-27

    ... National Oceanic and Atmospheric Administration RIN 0648-XV13 Atlantic Coastal Fisheries Cooperative Management Act Provisions; Atlantic Coastal Shark Fishery AGENCY: National Marine Fisheries Service (NMFS...-compliance; Declaration of a moratorium. SUMMARY: In accordance with the Atlantic Coastal...

  4. Sea surface temperatures in the North Atlantic Ocean from 30ka to 10ka

    Science.gov (United States)

    Barrack, Kerr; Greenop, Rosanna; Burke, Andrea; Barker, Stephen; Chalk, Thomas; Crocker, Anya

    2016-04-01

    Some of the most striking features of the Late Pleistocene interval are the rapid changes in climate between warmer interstadial and cold stadial periods which, when coupled, are termed Dansgaard-Oeschger (D-O) events. This shift between warm and cold climates has been interpreted to result from changes in the thermohaline circulation (Broecker et al., 1985) triggered by, for instance, freshwater input from the collapse of the Laurentide ice sheet (Zahn et al., 1997). However, a recent study suggests that major ice rafting events cannot be the 'trigger' for the centennial to millennial scale cooling events identified over the past 500kyr (Barker at al., 2015). Polar planktic foraminiferal and lithogenic/terrigenous grain counts reveal that the southward migration of the polar front occurs before the deposition of ice rafted debris and therefore the rafting of ice during stadial periods. Based upon this evidence, Barker et al. suggest that the transition to a stadial state is a non-linear response to gradual cooling in the region. In order to test this hypothesis, our study reconstructs sea surface temperature across D-O events and the deglaciation in the North Atlantic between 30ka and 10ka using Mg/ Ca paleothermometry in Globigerina bulloides at ODP Sites 980 and 983 (the same sites as used in Barker et al., 2015) with an average sampling resolution of 300 years. With our new record we evaluate the timing of surface ocean temperature change, frontal shift movement, and ice rafting to investigate variations in the temperature gradient across the polar front over D-O events. References: Barker, S., Chen, J., Gong, X., Jonkers, L., Knorr, G., Thornalley, D., 2015. Icebergs not the trigger for North Atlantic cold events. Nature, 520(7547), pp.333-336. Broecker, W.S., Peteer, D.M., Rind, D., 1985. Does the ocean-atmosphere system have more than one stable mode of operation? Nature, 315 (6014), pp.21-26. Zahn, R., Schönfeld, J., Kudrass, H.-R., Park, M

  5. Atlantic Offshore Seabird Dataset Catalog

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Several bureaus within the Department of Interior compiled available information from seabird observation datasets from the Atlantic Outer Continental Shelf into a...

  6. Atlantic Flyway Sea Duck Survey

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Atlantic Flyway Sea Duck Survey, conducted from 1991 to 2002 by the U.S. Fish and Wildlife Service, was established to record sea duck numbers using near shore...

  7. Virginia Atlantic Coast Recreational Use

    Data.gov (United States)

    Virginia Department of Environmental Quality — As a member of the Mid-Atlantic Regional Council on the Ocean (MARCO), Virginia, through its Coastal Zone Management (CZM) Program, collected information on how the...

  8. VA Atlantic Coast Recreational Use

    Data.gov (United States)

    Virginia Department of Environmental Quality — As a member of the Mid-Atlantic Regional Council on the Ocean (MARCO), Virginia, through its Coastal Zone Management (CZM) Program, collected information on how the...

  9. Atlantic Flyway Breeding Waterfowl Survey

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Atlantic Flyway Technical Section initiated this breeding waterfowl survey in 11 northeast states ranging from New Hampshire to Virginia.

  10. North Atlantic warming: patterns of long-term trend and multidecadal variability

    Energy Technology Data Exchange (ETDEWEB)

    Polyakov, Igor V.; Alexeev, Vladimir A.; Zhang, Xiangdong [University of Alaska Fairbanks, International Arctic Research Center, Fairbanks, AK (United States); Bhatt, Uma S. [University of Alaska Fairbanks, Geophysical Institute, Fairbanks, AK (United States); Polyakova, Evgenia I. [Stanford University, Department of Geological and Environmental Studies, Stanford, CA (United States)

    2010-02-15

    Climate fluctuations in the North Atlantic Ocean have wide-spread implications for Europe, Africa, and the Americas. This study assesses the relative contribution of the long-term trend and variability of North Atlantic warming using EOF analysis of deep-ocean and near-surface observations. Our analysis demonstrates that the recent warming over the North Atlantic is linked to both long-term (including anthropogenic and natural) climate change and multidecadal variability (MDV, {proportional_to}50-80 years). Our results suggest a general warming trend of 0.031 {+-} 0.006 C/decade in the upper 2,000 m North Atlantic over the last 80 years of the twentieth century, although during this time there are periods in which short-term trends were strongly amplified by MDV. For example, MDV accounts for {proportional_to}60% of North Atlantic warming since 1970. The single-sign basin-scale pattern of MDV with prolonged periods of warming (cooling) in the upper ocean layer and opposite tendency in the lower layer is evident from observations. This pattern is associated with a slowdown (enhancement) of the North Atlantic thermohaline overturning circulation during negative (positive) MDV phases. In contrast, the long-term trend exhibits warming in tropical and mid-latitude North Atlantic and a pattern of cooling in regions associated with major northward heat transports, consistent with a slowdown of the North Atlantic circulation as evident from observations and confirmed by selected modeling results. This localized cooling has been masked in recent decades by warming during the positive phase of MDV. Finally, since the North Atlantic Ocean plays a crucial role in establishing and regulating the global thermohaline circulation, the multidecadal fluctuations discussed here should be considered when assessing long-term climate change and variability, both in the North Atlantic and at global scales. (orig.)

  11. The Medieval Climate Anomaly and Little Ice Age in Chesapeake Bay and the North Atlantic Ocean

    Science.gov (United States)

    Cronin, T. M.; Hayo, K.; Thunell, R.C.; Dwyer, G.S.; Saenger, C.; Willard, D.A.

    2010-01-01

    A new 2400-year paleoclimate reconstruction from Chesapeake Bay (CB) (eastern US) was compared to other paleoclimate records in the North Atlantic region to evaluate climate variability during the Medieval Climate Anomaly (MCA) and Little Ice Age (LIA). Using Mg/Ca ratios from ostracodes and oxygen isotopes from benthic foraminifera as proxies for temperature and precipitation-driven estuarine hydrography, results show that warmest temperatures in CB reached 16-17. ??C between 600 and 950. CE (Common Era), centuries before the classic European Medieval Warm Period (950-1100. CE) and peak warming in the Nordic Seas (1000-1400. CE). A series of centennial warm/cool cycles began about 1000. CE with temperature minima of ~. 8 to 9. ??C about 1150, 1350, and 1650-1800. CE, and intervening warm periods (14-15. ??C) centered at 1200, 1400, 1500 and 1600. CE. Precipitation variability in the eastern US included multiple dry intervals from 600 to 1200. CE, which contrasts with wet medieval conditions in the Caribbean. The eastern US experienced a wet LIA between 1650 and 1800. CE when the Caribbean was relatively dry. Comparison of the CB record with other records shows that the MCA and LIA were characterized by regionally asynchronous warming and complex spatial patterns of precipitation, possibly related to ocean-atmosphere processes. ?? 2010.

  12. The North Atlantic Oscillation as a driver of rapid climate change in the Northern Hemisphere

    Science.gov (United States)

    Delworth, Thomas L.; Zeng, Fanrong; Vecchi, Gabriel A.; Yang, Xiaosong; Zhang, Liping; Zhang, Rong

    2016-07-01

    Pronounced climate changes have occurred since the 1970s, including rapid loss of Arctic sea ice, large-scale warming and increased tropical storm activity in the Atlantic. Anthropogenic radiative forcing is likely to have played a major role in these changes, but the relative influence of anthropogenic forcing and natural variability is not well established. The above changes have also occurred during a period in which the North Atlantic Oscillation has shown marked multidecadal variations. Here we investigate the role of the North Atlantic Oscillation in these rapid changes through its influence on the Atlantic meridional overturning circulation and ocean heat transport. We use climate models to show that observed multidecadal variations of the North Atlantic Oscillation can induce multidecadal variations in the Atlantic meridional overturning circulation and poleward ocean heat transport in the Atlantic, extending to the Arctic. Our results suggest that these variations have contributed to the rapid loss of Arctic sea ice, Northern Hemisphere warming, and changing Atlantic tropical storm activity, especially in the late 1990s and early 2000s. These multidecadal variations are superimposed on long-term anthropogenic forcing trends that are the dominant factor in long-term Arctic sea ice loss and hemispheric warming.

  13. The Atlantic Meridional Overturning Circulation's Response to Variable Buoyancy Forcing

    Science.gov (United States)

    Butler, Edward; Oliver, Kevin; Hirschi, Joël

    2014-05-01

    The Meridional Overturning Circulation (MOC) is a large-scale global circulation of water (and heat) throughout the world's ocean. It is an integral part of the climate system, responsible for significant anomalous warming of the North Atlantic region. Much of our current understanding of the MOC is based on equilibrium theories. However, the MOC is not a steady circulation and exhibits variability across a broad range of timescales. We examine the transient response of global ocean overturning, with particular emphasis on the Atlantic MOC (AMOC), to periodic variations in the North Atlantic meridional density gradient on decadal, centennial, and millennial timescales within the Nucleus for European Modelling of the Ocean (NEMO) model framework. We use the ORCA2 global ocean configuration of NEMO (with realistic topography and a horizontal resolution of 2°) and impose periodic variations in air temperature over the North Atlantic. In response, we see large oscillations in the strength of the AMOC which peak in magnitude at 128-year timescales. A scaling relationship of the form Ψ ~ ΔρH2 (in which Δρ is a measure of meridional density gradient and H is the depth scale of maximal overturning) is found to hold for the AMOC in these transient simulations with strongest correlations observed at centennial timescales. We explore the validity of this scaling relationship across a broad range of spatial and temporal scales and discuss its validity in a global context.

  14. AMO-like variations of holocene sea surface temperatures in the North Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    S. Feng

    2009-12-01

    Full Text Available Instrumental records of the North Atlantic sea surface temperatures (SST show a significant 60–80 year cycle, referred to as the Atlantic Multidecadal Oscillation (AMO. During AMO warm (cold phases, SST over the entire North Atlantic Ocean is dominated by basin-wide positive (negative anomalies. We analyzed SST variations in the North Atlantic Ocean for the last 10 ka. The long-term and centennial variations of Holocene SST in the North Atlantic demonstrate a basin-wide mode that clearly resembles the AMO signal recorded during the recent instrumental period. The long-term changes of Holocene SST were controlled by the solar insolation related to the orbital variations, and the centennial variations were closely coupled with the intensity of the thermohaline circulation. The spatial extent in the Atlantic realm of temperature anomalies around two specific time intervals, 8.2 ka and during the medieval warm period, also resemble the observed temperature anomalies associated with the AMO. These results demonstrate that the modern AMO, and centennial and longer time scale SST variations during the Holocene share a similar spatial extent in the North Atlantic, and presumably as well physical processes associated with their existence and their far-field teleconnection effects.

  15. Burst feeding of Pelagia noctiluca ephyrae on Atlantic bluefin tuna (Thunnus thynnus eggs.

    Directory of Open Access Journals (Sweden)

    Ana Gordoa

    Full Text Available This study investigates the predation of P. noctiluca ephyrae on Atlantic Bluefin tuna (ABFT eggs under different experimental conditions. The specific factors considered in the experimental design were: a water mix conditions to explore predation under two-dimensional (2D and three-dimensional (3D prey distributions, b prey density to investigate the ingestion rate capacity, and c incubation time to inspect gut saturation. The eggs and jellyfish ephyrae were collected during the 2012 ABFT spawning survey off Ibiza (Balearic Isl., Western Mediterranean. The results showed that the proportion of feeding ephyrae increased with size. The mean clearance rate of feeding ephyrae, 4.14 L h(-1, was the highest ever recorded for ephyrae. Under calm conditions the eggs floated at the surface (2D spatial arrangement and the clearance rates, at low prey densities, were at least twice those under mixed conditions (3D spatial arrangement. At high prey density, clearance rate did not differ between mix conditions, probably due to the fast gut saturation, which was reached in c.a. 15 min, as revealed by time series observations of gut contents. The fast saturation of ephyrae and their slow digestion time of approximately 18 h suggest the existence of a diel feeding periodicity. We conclude that in the Western Mediterranean, P. noctiluca ephyrae are capable of predating on ABFT eggs, a highly pulsed and spatially restricted resource that potentially switches from a 3D to a 2D configuration in the absence of wind-generated turbulence. The P. noctiluca and Atlantic Bluefin tuna egg system might represent an example of a general mechanism linking pelagic and neustonic food webs.

  16. Mid to late Holocene strengthening of the East Greenland Current linked to warm subsurface Atlantic water

    Science.gov (United States)

    Perner, Kerstin; Moros, Matthias; Lloyd, Jeremy M.; Jansen, Eystein; Stein, Rüdiger

    2015-12-01

    The relatively fresh and cold East Greenland Current (EGC) connects the Arctic with the subpolar North Atlantic Ocean. Its strength and influence on the freshwater balance in the North Atlantic affects both the Subpolar Gyre dynamics and deep convection in the Labrador Sea. Enhanced freshwater and sea-ice expansion in the subpolar North Atlantic is suggested to modify the northward heat transport within the North Atlantic Current. High-resolution palaeoceanographic reconstructions, based on planktic and benthic foraminifera assemblage data, from the central East Greenland shelf (Foster Bugt) reveal distinct centennial to millennial-scale oceanographic variability that relates to climatic changes during the mid to late Holocene (the last c. 6.3 ka BP). Our data highlight intervals of cooling and freshening of the polar surface EGC waters that accompany warming in the subsurface Atlantic waters, which are a combination of chilled Atlantic Intermediate Water (AIW) from the Arctic Ocean and of the Return Atlantic Current (RAC) from the West Spitsbergen Current (WSC). Mid Holocene thermal optimum conditions prevailed until c. 4.5 ka BP. A thin/absent surface Polar Water layer, low drift/sea-ice occurrence and strong contribution of recirculating warm Atlantic waters at the subsurface, suggest a relatively weak EGC during this period. Subsequently, between 1.4 and 4.5 ka BP, the water column became well stratified as the surface Polar Water layer thickened and cooled, indicating a strong EGC. This EGC strengthening parallelled enhanced subsurface chilled AIW contribution from the Arctic Ocean after c. 4.5 ka BP, which culminated from 1.4 to 2.3 ka BP. This coincides with warming identified in earlier work of the North Atlantic Current, the Irminger Current, and the West Greenland Current. We link the enhanced contribution of chilled Atlantic Water during this period to the time of the 'Roman Warm Period'. The observed warming offshore East Greenland, centred at c. 1.8 ka

  17. Dietary histidine supplementation prevents cataract development in adult Atlantic salmon, Salmo salar L., in seawater

    OpenAIRE

    Waagbø, Rune; Tröße, Christiane; Koppe, Wolfgang; Fontanillas, Ramon; Breck, Olav

    2010-01-01

    The aim of the present study was to investigate the cataract preventive effect of dietary histidine regimes in adult Atlantic salmon (Salmo salar L.) in seawater, both through manipulating the dietary histidine level and feeding period. Mean body weight of individually tagged Atlantic salmon at the start of the experiment was 1662 (SD 333) g. Low prevalence of mild cataracts were recorded in the beginning of June. Three fishmeal and fish oil-based extruded diets (crude protein: 375 g...

  18. Atmospheric multidecadal variations in the North Atlantic realm: proxy data, observations, and atmospheric circulation model studies

    OpenAIRE

    Grosfeld, K.; G. Lohmann; N. Rimbu; Fraedrich, K.; F. Lunkeit

    2007-01-01

    We investigate the spatial and temporal characteristics of multidecadal climate variability in the North Atlantic realm, using observational data, proxy data and model results. The dominant pattern of multidecadal variability of SST depicts a monopolar structure in the North Atlantic during the instrumental period with cold (warm) phases during 1900–1925 and 1970–1990 (1870–1890 and 1940–1960). Two atmospheric general circulation models of different com...

  19. The atmospheric response to North Atlantic SST anomalies in seasonal prediction experiments

    OpenAIRE

    Lin, Hai; DEROME, JACQUES

    2011-01-01

    Seasonal forecasts performed over a 26 yr period as part of the Historical Seasonal Forecasting Project (HFP) are used to analyze the influence of North Atlantic sea surface temperature (SST) anomalies on the atmospheric circulation, its seasonality, and model dependence. The signals related to the El Ni˜no events are first removed from both the SST and the atmospheric data. The North Atlantic SST and the ensemble mean forecast are then correlated over the 26 yr to identify the model response...

  20. 78 FR 59878 - Atlantic Highly Migratory Species; Commercial Atlantic Aggregated Large Coastal Shark (LCS...

    Science.gov (United States)

    2013-09-30

    ... management groups is closed, even across fishing years. On July 3, 2013 (78 FR 40318), NMFS announced the... Species; Commercial Atlantic Aggregated Large Coastal Shark (LCS), Atlantic Hammerhead Shark, Atlantic Blacknose Shark, and Atlantic Non-Blacknose Small Coastal Shark (SCS) Management Groups AGENCY:...

  1. Atlantic menhaden processing plant test tagging data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Atlantic menhaden are a schooling forage fish species, which are subject to a large commercial purse seine fishery. Atlantic menhaden are harvested for reduction...

  2. Atlantic NAD 83 OCS Planning Areas

    Data.gov (United States)

    Bureau of Ocean Energy Management, Department of the Interior — This data set contains BOEM Planning Area outlines in ESRI shapefile format for the BOEM Atlantic Region. The old Atlantic Planning Area outlines were changed as of...

  3. The North Atlantic Oscillation in the Atlantic-European SLP*

    OpenAIRE

    GLOWIENKA-HENSE, RITA

    2011-01-01

    An analysis of the signature of the North Atlantic Oscillation (NAO) in the Atlantic-European sea level pressure (SLP) is presented for observed (German Weather Service) and ECMWF T21 model data. The former time series consists of 1881–1984 January to December fields and the latter of 42 monthly fields from 3 permanent January simulations. The NAO is shown to be one of the dominant eigenmodes of SLP for all calendar months. A very similar NAO anomaly pattern is filtered from the T21 model dat...

  4. Atlantic Seaduck Project

    Science.gov (United States)

    Perry, M.C.; Hanson, Alan; Kerekes, Joseph; Paquet, Julie

    2006-01-01

    Atlantic Seaduck Project is being conducted to learn more about the breeding and moulting areas of seaducks in northern Canada and more about their feeding ecology on wintering areas, especially Chesapeake Bay. Satellite telemetry is being used to track surf scoters wintering in Chesapeake Bay, Maryland and black scoters on migrational staging areas in New Brunswick, Canada to breeding and moulting areas in northern Canada. Various techniques used to capture the scoters included mist netting, night-lighting, and net capture guns. All captured ducks were transported to a veterinary hospital where surgery was conducted following general anaesthesia procedures. A PTT100 transmitter (39 g) manufactured by Microwave, Inc., Columbia, Maryland was implanted into the duck?s abdominal cavity with an external (percutaneous) antenna. Eight of the surf scoters from Chesapeake Bay successfully migrated to possible breeding areas in Canada and all 13 of the black scoters migrated to suspected breeding areas. Ten of the 11 black scoter males migrated to James Bay presumably for moulting. Updated information from the ARGOS Systems aboard the NOAA satellites on scoter movements was made accessible on the Patuxent Website. Habitat cover types of locations using GIS (Geographical Information Systems) and aerial photographs (in conjunction with remote sensing software) are currently being analyzed to build thematic maps with varying cosmetic layer applications. Many factors related to human population increases have been implicated in causing changes in the distribution and abundance of wintering seaducks. Analyses of the gullet (oesophagus and proventriculus) and the gizzard of seaducks are currently being conducted to determine if changes from historical data have occurred. Scoters in the Bay feed predominantly on the hooked mussel and several species of clams. The long-tailed duck appears to select the gem clam in greater amounts than other seaducks, but exhibits a diverse diet of

  5. Correlation of lacustrine paleoclimate records from Mono Lake with the North Atlantic using paleomagnetic intensity

    Science.gov (United States)

    Zimmerman, S. R. H.; Hemming, S. R.; Kent, D. V.

    2003-04-01

    The Wilson Creek Formation of Mono Lake, CA is a Late Pleistocene lacustrine sequence that records major shifts in the paleoenvironment of the lake. It has also been shown to be an excellent recorder of the past variations of the Earth’s magnetic field, and is important as the type section of the Mono Lake Excursion (MLE). As with many terrestrial records, however, it has proven to be very challenging to date the Wilson Creek Fm. at high resolution. Radiocarbon dating has been shown to be vulnerable to contamination with modern carbon, while 40Ar/39Ar dating of the rhyolitic ashes is complicated by inclusion of older xenocrysts. Benson et al. (1998; QR, v. 49, 1-10 ) suggested a correlation to North Atlantic records using paleomagnetic inclination and intensity combined with radiocarbon ages. They argued that δ18O of the Wilson Creek sediments represents variations in lake level, with prominent dry periods (high δ18O) correlating to the North Atlantic Heinrich events. We generated a relative paleointensity record for the Wilson Creek section and propose an alternative correlation to the North Atlantic Paleomagnetic Intensity Stack (NAPIS-75; Laj et al. 2000, Phil. Trans. R. Soc., v. 358, 1009-1025) and the GISP2 age model. It was recently demonstrated by Stoner et al. (2002, QSR v. 21, 1141-1151) that variations in the Earth’s paleomagnetic field intensity are correlative both at high-resolution (10^3 yr) and over long distances (10^4 km). Assuming that the MLE is equivalent to the Laschamp Excursion and that the lake expanded early in Marine Isotope Stage 4, a simple correlation of the major features of the NAPIS-75 and Mono records places the Wilson Creek Fm. on the GISP2 age model, and allows correlation of that paleoclimate record to other records also on that time scale. We also interpret the major δ18O excursions as Heinrich correlatives; however, our correlation equates the three older excursions to H4, H5, and H6 (rather than H3, no correl., and H4

  6. Atlantic CFC data in CARINA

    Directory of Open Access Journals (Sweden)

    R. Steinfeldt

    2010-01-01

    Full Text Available Water column data of carbon and carbon-relevant parameters have been collected and merged into a new database called CARINA (CARbon IN the Atlantic. In order to provide a consistent data set, all data have been examined for systematic biases and adjusted if necessary (secondary quality control (QC. The CARINA data set is divided into three regions: the Arctic/Nordic Seas, the Atlantic region and the Southern Ocean. Here we present the CFC data for the Atlantic region, including the chlorofluorocarbons CFC-11, CFC-12 and CFC-113 as well as carbon tetrachloride (CCl4. The methods applied for the secondary quality control, a crossover analyses, the investigation of CFC ratios in the ocean and the CFC surface saturation are presented. Based on the results, the CFC data of some cruises are adjusted by a certain factor or given a "poor'' quality flag.

  7. Atlantic versus Indo-Pacific influence on Atlantic-European climate

    OpenAIRE

    Pohlmann, Holger; Latif, Mojib

    2005-01-01

    The influence of the Atlantic and Indo-Pacific oceans on Atlantic-European climate is investigated by analyzing ensemble integrations with the atmospheric general circulation model ECHAM4 forced by anomalous sea surface temperature and sea ice conditions restricted to the Atlantic (AOGA) and Indo-Pacific (I+POGA) oceans. The forcing from both the Indo-Pacific and Atlantic oceans are important for the generation of the sea level pressure (SLP) variability in the Atlantic region in the boreal w...

  8. Arctic warming will promote Atlantic-Pacific fish interchange

    Science.gov (United States)

    Wisz, M. S.; Broennimann, O.; Grønkjær, P.; Møller, P. R.; Olsen, S. M.; Swingedouw, D.; Hedeholm, R. B.; Nielsen, E. E.; Guisan, A.; Pellissier, L.

    2015-03-01

    Throughout much of the Quaternary Period, inhospitable environmental conditions above the Arctic Circle have been a formidable barrier separating most marine organisms in the North Atlantic from those in the North Pacific. Rapid warming has begun to lift this barrier, potentially facilitating the interchange of marine biota between the two seas. Here, we forecast the potential northward progression of 515 fish species following climate change, and report the rate of potential species interchange between the Atlantic and the Pacific via the Northwest Passage and the Northeast Passage. For this, we projected niche-based models under climate change scenarios and simulated the spread of species through the passages when climatic conditions became suitable. Results reveal a complex range of responses during this century, and accelerated interchange after 2050. By 2100 up to 41 species could enter the Pacific and 44 species could enter the Atlantic, via one or both passages. Consistent with historical and recent biodiversity interchanges, this exchange of fish species may trigger changes for biodiversity and food webs in the North Atlantic and North Pacific, with ecological and economic consequences to ecosystems that at present contribute 39% to global marine fish landings.

  9. The Cretaceous opening of the South Atlantic Ocean

    Science.gov (United States)

    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 (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.

  10. Temperature calibration of Mg/Ca ratios in the intermediate water benthic foraminifer Hyalinea balthica

    NARCIS (Netherlands)

    Rosenthal, Y.; Morley, A.; Barras, C.; Katz, M.E.; Jorissen, F.; Reichart, G.-J.; Oppo, D.W.; Linsley, B.K.

    2011-01-01

    Core top samples from Indonesian and northeast Atlantic depth transects were used to calibrate Mg/Ca and δ18O in tests of the calcitic benthic foraminifer Hyalinea balthica to bottom water temperature between 4°C and 13°C. This shallow infaunal species is primarily abundant in neritic to upper bathy

  11. Variability in north tropical atlantic over the last 20 000 years and holocene gulf stream activity; Variabilite au cours des derniers 20 000 ans de l'hydrologie de l'atlantique tropical nord et de l'activite du gulf stream a partir de la composition isotopique de l'oxygene et de la composition en elements trace des foraminferes planctoniques profonds

    Energy Technology Data Exchange (ETDEWEB)

    Cleroux, C

    2007-10-15

    Modern oceanographical studies shown that most of the ocean heat content in the North Atlantic Western Boundary Current region is stored in the upper 400 meters. To study past heat content and Gulf Stream activity, we performed coupled analyses of oxygen isotopic and trace elemental composition on several foraminifera species to reconstruct upper water column temperature and salinity. Calcification depths of Globorotalia inflata, Globorotalia truncatulinoides and Pulleniatina obliquiloculata have been constrain by correlating modern hydrographic data to oxygen isotopic measurement of North Atlantic core-top samples. We found that the three deep-dwelling foraminifera species have a preferred habitat at the base of the seasonal thermocline (Cleroux et al, 2007). The same set of North Atlantic core-tops has been used to define relationships between trace elemental compositions and temperature. We established calibrations between Mg/Ca ratio or Sr/Ca ratio and temperature for the three deep-dwelling foraminifera (Cleroux et al, submitted). We apply this strategy on the core MD99-2203 located off Cape Hatteras where the Gulf Stream separate from the United States coast. High-resolution surface reconstructions over the Holocene show low amplitude periodic temperature and salinity changes that could be related to NAO type mechanisms. Large hydrological changes in sub-surface reflect variations of Labrador current and Mode Water influences. Using recent studies on Mode Water formation and Gulf Stream heat advection, we interpret our results in term of ocean heat content and Gulf Stream activity. (author)

  12. Estimation of Atlantic-Mediterranean netflow variability

    Science.gov (United States)

    Guerreiro, Catarina; Peliz, Alvaro; Miranda, Pedro

    2016-04-01

    The exchanges at the Strait of Gibraltar are extremely difficult to measure due to the strong temporal and across-strait variabilities; yet the Atlantic inflow into the Mediterranean is extremely important both for climate and to ecosystems. Most of the published numerical modeling studies do not resolve the Strait of Gibraltar realistically. Models that represent the strait at high resolution focus primarily in high frequency dynamics, whereas long-term dynamics are studied in low resolution model studies, and for that reason the Strait dynamics are poorly resolved. Estimating the variability of the exchanges requires long term and high-resolutions studies, thus an improved simulation with explicit and realistic representation of the Strait is necessary. On seasonal to inter-annual timescales the flow is essentially driven by the net evaporation contribution and consequently realistic fields of precipitation and evaporation are necessary for model setup. A comparison between observations, reanalysis and combined products shows ERA-Interim Reanalysis has the most suitable product for Mediterranean Sea. Its time and space variability are in close agreement with NOC 1.1 for the common period (1980 - 1993) and also with evaporation from OAFLUX (1989 - 2014). Subinertial fluctuations, periods from days to a few months, are the second most energetic, after tides, and are the response to atmospheric pressure fluctuations and local winds. Atmospheric pressure fluctuations in the Mediterranean cause sea level oscillations that induce a barotropic flow through the Strait. Candela's analytical model has been used to quantify this response in later studies, though comparison with observations points to an underestimation of the flow at strait. An improved representation of this term contribution to the Atlantic - Mediterranean exchange must be achieved on longer time-scales. We propose a new simulation for the last 36 years (1979 - 2014) for the Mediterranean - Atlantic

  13. The Effects of Temperature and Salinity on Mg Incorporation in Planktonic Foraminifera Globigerinoides ruber (white): Results from a Global Sediment Trap Mg/Ca Database

    Science.gov (United States)

    Gray, W. R.; Weldeab, S.; Lea, D. W.

    2015-12-01

    Mg/Ca in Globigerinoides ruber is arguably the most important proxy for sea surface temperature (SST) in tropical and sub tropical regions, and as such guides our understanding of past climatic change in these regions. However, the sensitivity of Mg/Ca to salinity is debated; while analysis of foraminifera grown in cultures generally indicates a sensitivity of 3 - 6% per salinity unit, core-top studies have suggested a much higher sensitivity of between 15 - 27% per salinity unit, bringing the utility of Mg/Ca as a SST proxy into dispute. Sediment traps circumvent the issues of dissolution and post-depositional calcite precipitation that hamper core-top calibration studies, whilst allowing the analysis of foraminifera that have calcified under natural conditions within a well constrained period of time. We collated previously published sediment trap/plankton tow G. ruber (white) Mg/Ca data, and generated new Mg/Ca data from a sediment trap located in the highly-saline tropical North Atlantic, close to West Africa. Calcification temperature and salinity were calculated for the time interval represented by each trap/tow sample using World Ocean Atlas 2013 data. The resulting dataset comprises >240 Mg/Ca measurements (in the size fraction 150 - 350 µm), that span a temperature range of 18 - 28 °C and 33.6 - 36.7 PSU. Multiple regression of the dataset reveals a temperature sensitivity of 7 ± 0.4% per °C (p changes when variations in salinity are accounted for.

  14. The Effects of Temperature and Salinity on Mg Incorporation in Planktonic Foraminifera Globigerinoides ruber (white): Results from a Global Sediment Trap Mg/Ca Database

    Science.gov (United States)

    Gray, W. R.; Weldeab, S.; Lea, D. W.

    2015-12-01

    Mg/Ca in Globigerinoides ruber is arguably the most important proxy for sea surface temperature (SST) in tropical and sub tropical regions, and as such guides our understanding of past climatic change in these regions. However, the sensitivity of Mg/Ca to salinity is debated; while analysis of foraminifera grown in cultures generally indicates a sensitivity of 3 - 6% per salinity unit, core-top studies have suggested a much higher sensitivity of between 15 - 27% per salinity unit, bringing the utility of Mg/Ca as a SST proxy into dispute. Sediment traps circumvent the issues of dissolution and post-depositional calcite precipitation that hamper core-top calibration studies, whilst allowing the analysis of foraminifera that have calcified under natural conditions within a well constrained period of time. We collated previously published sediment trap/plankton tow G. ruber (white) Mg/Ca data, and generated new Mg/Ca data from a sediment trap located in the highly-saline tropical North Atlantic, close to West Africa. Calcification temperature and salinity were calculated for the time interval represented by each trap/tow sample using World Ocean Atlas 2013 data. The resulting dataset comprises >240 Mg/Ca measurements (in the size fraction 150 - 350 µm), that span a temperature range of 18 - 28 °C and 33.6 - 36.7 PSU. Multiple regression of the dataset reveals a temperature sensitivity of 7 ± 0.4% per °C (p < 2.2*10-16) and a salinity sensitivity of 4 ± 1% per salinity unit (p = 2*10-5). Application of this calibration has significant implications for both the magnitude and timing of glacial-interglacial temperature changes when variations in salinity are accounted for.

  15. Variations of the Atlantic and Pacific Blocking Anticyclones and Their Correlation in the Northern Hemisphere

    Institute of Scientific and Technical Information of China (English)

    HUANG Fei; ZHOU Faxiu; Olson P.J

    2002-01-01

    Blocking is a large-scale, mid-latitude atmospheric anticyclone that splits the westerly into two jets and has a profound effect on local and regional climates. This study examined the seasonal, interannual, and decadal variability of the Atlantic and Pacific blocking anticyclones in the Northern Hemisphere based on the National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) reanalysis data between 1958 and 1999. The preferred blocking region during these forty-two years was located over the Atlantic. Most blocking anticyclones over the Atlantic occurred in spring, while most of those over the Pacific occurred in winter. Similar two-to four-year and eleven-year oscillations were found for both the Atlantic and Pacific blocks by using wavelet analysis. The dominant mode for the Pacific blocks is decadal variation, while for the Atlantic blocks the predominant one is interannual variation with a period of about three years. The frequencies of the Pacific and Atlantic blocks varied almost in phase on interannual time scales except during the period of 1965-1977, and frequencies were out of phase on decadal time scale throughout the forty-two years.

  16. The Ca(2+)/Calmodulin/CaMKK2 Axis: Nature's Metabolic CaMshaft.

    Science.gov (United States)

    Marcelo, Kathrina L; Means, Anthony R; York, Brian

    2016-10-01

    Calcium (Ca(2+)) is an essential ligand that binds its primary intracellular receptor calmodulin (CaM) to trigger a variety of downstream processes and pathways. Central to the actions of Ca(2+)/CaM is the activation of a highly conserved Ca(2+)/CaM kinase (CaMK) cascade that amplifies Ca(2+) signals through a series of subsequent phosphorylation events. Proper regulation of Ca(2+) flux is necessary for whole-body metabolism and disruption of Ca(2+) homeostasis has been linked to various metabolic diseases. Here we provide a synthesis of recent advances that highlight the roles of the Ca(2+)/CaMK axis in key metabolic tissues. An appreciation of this information is critical to understanding the mechanisms by which Ca(2+)/CaM-dependent signaling contributes to metabolic homeostasis and disease.

  17. Latitudinal distribution of Trichodesmium spp. and N2 fixation in the Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    E. Marañón

    2010-10-01

    Full Text Available We have determined the latitudinal distribution of Trichodesmium spp. abundance and community N2 fixation in the Atlantic Ocean along a meridional transect from ca. 30° N to 30° S in November–December 2007 and April–May 2008. The observations from both cruises were highly consistent in terms of absolute magnitude and latitudinal distribution, showing a strong association between Trichodesmium abundance and community N2 fixation. The highest Trichodesmium abundances (mean = 220 trichomes L−1, and community N2 fixation rates (mean = 60 μmol m−2 d−1 occurred in the Equatorial region between 5° S–15° N. In the South Atlantic gyre, Trichodesmium abundance was very low (ca. 1 trichome L−1 but N2 fixation was always measurable, averaging 3 and 10 μmol m2 d−1 in 2007 and 2008, respectively. We suggest that N2 fixation in the South Atlantic was sustained by other, presumably unicellular, diazotrophs. Comparing these distributions with the geographical pattern in atmospheric dust deposition points to iron supply as the main factor determining the large scale latitudinal variability of Trichodesmium spp. abundance and N2 fixation in the Atlantic Ocean. We observed a marked South to North decrease in surface phosphate concentration, which argues against a role for phosphorus availability in controlling the large scale distribution of N2 fixation. Scaling up from all our measurements (42 stations results in conservative estimates for total N2 fixation of ∼6 TgN yr−1 in the North Atlantic (0–40° N and ~1.2 TgN yr−1 in the South Atlantic (0–40° S.

  18. Latitudinal distribution of Trichodesmium spp. and N2 fixation in the Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    E. Marañón

    2010-03-01

    Full Text Available We have determined the latitudinal distribution of Trichodesmium spp. abundance and community N2 fixation in the Atlantic Ocean along a meridional transect from ca. 30° N to 30° S in November–December 2007 and April–May 2008. The observations from both cruises were highly consistent in terms of absolute magnitude and latitudinal distribution, showing a strong association between Trichodesmium abundance and community N2 fixation. The highest Trichodesmium abundances (mean = 220 trichomes L−1 and community N2 fixation rates (mean = 60 μmol m−2 d−1 occurred in the Equatorial region between 5° S–15° N. In the South Atlantic gyre, Trichodesmium abundance was very low (ca. 1 trichome L−1 but N2 fixation was always measurable, averaging 3 and 10 μmol m2 d−1 in 2007 and 2008, respectively. We suggest that N2 fixation in the South Atlantic was sustained by other, presumably unicellular, diazotrophs. Comparing these distributions with the geographical pattern in atmospheric dust deposition points to iron supply as the main factor determining the large scale latitudinal variability of Trichodesmium spp. abundance and N2 fixation in the Atlantic Ocean. We observed a marked South to North decrease in surface phosphate concentration, which argues against a role for phosphorus availability in controlling the large scale distribution of N2 fixation. Scaling up from all our measurements (42 stations results in conservative estimates for total N2 fixation of ~6 TgN yr−1 in the North Atlantic (0–40° N and 1.2 TgN yr−1 in the South Atlantic (0–40° S.

  19. Extratropical North Atlantic SST influence on Sahel rainfall

    Science.gov (United States)

    Liu, Y.; Chiang, J. C.

    2013-12-01

    We present evidence suggesting that the late 1960's Sahel drought was linked to an abrupt cooling in the extratropical North Atlantic, whose influence was then propagated to the Sahel by atmospheric teleconnection. Such linkages have been observed in paleoclimate during abrupt climate changes of the last glacial period. They have also occurred in coupled model simulations of Atlantic meridional overturning circulation (AMOC) slowdown, the latter being the leading cause of said paleoclimate abrupt changes. The AMOC-slowdown simulations show a characteristic global pattern of climate changes, including a northern hemispheric-wide cooling and increased surface pressure, and weakening of the West African and Asian monsoons. We show that an observed northern-hemispheric pattern of changes, resembling the AMOC slowdown, occurred during the late 1960's, co-incident with the Sahel drought. A combined principal component analysis of 20th century surface temperature, sea level pressure and precipitation extracts a leading mode whose spatial pattern closely resemble the impacts of AMOC slowdown. A similar analysis of AMIP-type simulations forced by 20th century observed forcings shows a similar result, suggesting that the origins of the climate change reside in SST changes, in particular over extratropical North Atlantic. Taken together, the results suggests the influence of extratropical North Atlantic cooling on the 20th century Sahel drought, and a teleconnection pathway through surface/tropospheric cooling. Motivated by our observational result, we investigated atmospheric teleconnection mechanisms of extratropical North Atlantic cooling in an atmospheric general circulation model (GCM) coupled with slab ocean. Our results indicate the central role of tropospheric cooling in communicating the influence on the Sahel. We explicitly show this using regional climate model simulation of the Sahel, with air temperature and associated humidity anomalies from the GCM simulation

  20. Teale CA. Counties

    Data.gov (United States)

    California Department of Resources — California Spatial Information System (CaSIL) is a project designed to improve access to geo-spatial and geo-spatial related data information throughout the state...

  1. Summer North Atlantic Oscillation and flood variability in Switzerland

    Science.gov (United States)

    Peña, Juan Carlos; Schulte, Lothar; Badoux, Alexandre

    2016-04-01

    The study analyses the possible links between flood frequency in Switzerland and the North Atlantic dynamics over the last two centuries. Given the intricate topography of Switzerland, it will generate a territorial division to retain main physiographic and environmental dissimilarities between different regions. The flood variability in Switzerland over the period 1800-2010 has been determined from a flood damage index for July and August months. The index considers very severe and catastrophic floods from existing flood inventories, summarizing both the severity of these events, their spatial extent and the regional differences. Special attention will be focused on the disparities between flood dynamics at northern and southern slopes of the Alps. The analysis of the possible links between floods and North Atlantic dynamics is focused on the low-frequency atmospheric circulation patterns. Summer climate in the North Atlantic-European sector shows a principal pattern of year-to-year variability, although this pattern is weaker than the North Atlantic Oscillation (NAO) in winter and is confined to northern latitudes. By analogy the climatology community refers to this pattern as the Summer North Atlantic Oscillation (SNAO), which is defined as the main empirical orthogonal function of the standardized anomalies of the European mean sea level pressure during July and August. The flood damage index provides evidences of floods clusters in: 1830-1851, 1881-1927, 1977-1990 and 2005 to present. These clusters coincide with those reported from Switzerland and from some areas of the European continent such as the Czech Republic, Italy and the eastern half of the Iberian Peninsula. This link is not so close when compared with the flood occurrences in Germany. The analysis of the principal mode of low-frequency atmospheric variability shows that the Swiss river catchments situated on the center and southern flank of the Alps are affected by atmospherically unstable areas

  2. Arctic warming will promote Atlantic-Pacific fish interchange

    DEFF Research Database (Denmark)

    Wisz, Mary; Broennimann, O.; Grønkjær, Peter;

    2015-01-01

    the interchange of marine biota between the two seas. Here, we forecast the potential northward progression of 515 fish species following climate change, and report the rate of potential species interchange between the Atlantic and the Pacific via the Northwest Passage and the Northeast Passage. For this, we...... projected niche-based models under climate change scenarios and simulated the spread of species through the passages when climatic conditions became suitable. Results reveal a complex range of responses during this century, and accelerated interchange after 2050. By 2100 up to 41 species could enter......Throughout much of the Quaternary Period, inhospitable environmental conditions above the Arctic Circle have been a formidable barrier separating most marine organisms in the North Atlantic from those in the North Pacific. Rapid warming has begun to lift this barrier, potentially facilitating...

  3. Solar Influence on the North Atlantic Oscillation - Initial Results

    CERN Document Server

    Dacie, Sally

    2015-01-01

    Some initial investigations into various atmospheric phenomena and the influence of the solar cycle on weather have been made. Strongly negative North Atlantic Oscillation (NAO) indices, which cause cold and dry winter weather in North West Europe, rarely occur during periods of high solar activity. Coupling between the troposphere and stratosphere is discussed, particularly in the context of Polar-night jet oscillation events (defined by Hitchcock et al., 2013) and the Quasi-Biennial Oscillation. The energy of North Atlantic hurricanes (as indicated by the Accumulated Cyclone Energy Index, ACE) is also linked to solar activity, via UV heating at the tropopause (Elsner et al., 2010), and is suggested as a possible mechanism through which solar activity could influence the NAO. Finally the lack of solar influence on the NAO before $\\sim$ 1950 is addressed, with a possible cause being the smaller solar cycle amplitudes. This short report contains several ideas, which may be worth pursuing further.

  4. Atlantic forcing of persistent drought in West Africa.

    Science.gov (United States)

    Shanahan, T M; Overpeck, J T; Anchukaitis, K J; Beck, J W; Cole, J E; Dettman, D L; Peck, J A; Scholz, C A; King, J W

    2009-04-17

    Although persistent drought in West Africa is well documented from the instrumental record and has been primarily attributed to changing Atlantic sea surface temperatures, little is known about the length, severity, and origin of drought before the 20th century. We combined geomorphic, isotopic, and geochemical evidence from the sediments of Lake Bosumtwi, Ghana, to reconstruct natural variability in the African monsoon over the past three millennia. We find that intervals of severe drought lasting for periods ranging from decades to centuries are characteristic of the monsoon and are linked to natural variations in Atlantic temperatures. Thus the severe drought of recent decades is not anomalous in the context of the past three millennia, indicating that the monsoon is capable of longer and more severe future droughts.

  5. Crosstalk between mitochondrial and sarcoplasmic reticulum Ca2+ cycling modulates cardiac pacemaker cell automaticity.

    Directory of Open Access Journals (Sweden)

    Yael Yaniv

    Full Text Available BACKGROUND: Mitochondria dynamically buffer cytosolic Ca(2+ in cardiac ventricular cells and this affects the Ca(2+ load of the sarcoplasmic reticulum (SR. In sinoatrial-node cells (SANC the SR generates periodic local, subsarcolemmal Ca(2+ releases (LCRs that depend upon the SR load and are involved in SANC automaticity: LCRs activate an inward Na(+-Ca(2+ exchange current to accelerate the diastolic depolarization, prompting the ensemble of surface membrane ion channels to generate the next action potential (AP. OBJECTIVE: To determine if mitochondrial Ca(2+ (Ca(2+ (m, cytosolic Ca(2+ (Ca(2+ (c-SR-Ca(2+ crosstalk occurs in single rabbit SANC, and how this may relate to SANC normal automaticity. RESULTS: Inhibition of mitochondrial Ca(2+ influx into (Ru360 or Ca(2+ efflux from (CGP-37157 decreased [Ca(2+](m to 80 ± 8% control or increased [Ca(2+](m to 119 ± 7% control, respectively. Concurrent with inhibition of mitochondrial Ca(2+ influx or efflux, the SR Ca(2+ load, and LCR size, duration, amplitude and period (imaged via confocal linescan significantly increased or decreased, respectively. Changes in total ensemble LCR Ca(2+ signal were highly correlated with the change in the SR Ca(2+ load (r(2 = 0.97. Changes in the spontaneous AP cycle length (Ru360, 111 ± 1% control; CGP-37157, 89 ± 2% control in response to changes in [Ca(2+](m were predicted by concurrent changes in LCR period (r(2 = 0.84. CONCLUSION: A change in SANC Ca(2+ (m flux translates into a change in the AP firing rate by effecting changes in Ca(2+ (c and SR Ca(2+ loading, which affects the characteristics of spontaneous SR Ca(2+ release.

  6. Impacts of the North Atlantic Oscillation on stream water chemistry in mid-Wales

    OpenAIRE

    L. Ness; Neal, C.; Davies, T.D.; Reynolds, B.

    2002-01-01

    Analysis of winter stream chemistry data from the Afon Hafren in mid-Wales reveals links between stream chemistry and the North Atlantic Oscillation (NAO). K, Y, Al and dissolved organic carbon (DOC) concentrations increase during high NAO index months (relatively warm and wet weather), while Ca, Mg and NO3 concentrations increase during low NAO months (relatively cold and dry conditions) with the increased concentrations lasting int...

  7. Impacts of the North Atlantic Oscillation on stream water chemistry in mid-Wales

    OpenAIRE

    L. Ness; Neal, C.; Davies, T.D.; Reynolds, B.

    2004-01-01

    Analysis of winter stream chemistry data from the Afon Hafren in mid-Wales reveals links between stream chemistry and the North Atlantic Oscillation (NAO). K, Y, Al and dissolved organic carbon (DOC) concentrations increase during high NAO index months (relatively warm and wet weather), while Ca, Mg and NO3 concentrations increase during low NAO months (relatively cold and dry conditions) with the increased concentrations lasting into the next month. The cause of the concentration c...

  8. Drought modulated by North Atlantic sea surface temperatures for the last 3,000 years along the northwestern Gulf of Mexico

    Science.gov (United States)

    Livsey, Daniel; Simms, Alexander R.; Hangsterfer, Alexandra; Nisbet, Robert A.; DeWitt, Regina

    2016-03-01

    In 2012 the most severe United States drought since the 1930's occurred, highlighting the need for a better understanding of the climate factors driving droughts. Spatial-temporal analysis of United States precipitation data from 1900 to 1999 indicates that the Atlantic Multidecadal Oscillation (AMO) primarily modulates drought frequency. Tree rings provide the highest resolution and most spatially distributed drought records beyond secular time-series; however, as most tree-ring records only extend to ca. 1000 years before present (BP), a new broadly distributed, quantitative, multi-millennial, proxy of past drought is needed to determine if the AMO modulated drought across North America through the late Holocene. In this study, we develop a new quantitative drought proxy from a transfer function between X-Ray Fluorescence (XRF) derived elemental data from a Texas playa and a tree-ring drought record. Using this transfer function, a 954-year tree-ring drought record was extended to ca. 3000 BP. Changes in the extended drought record correspond with timing of the Roman Climate Optimum, Medieval Warm Period, Little Ice Age, and changes in the AMO as recorded in a proxy record derived from North Atlantic ice-rafted debris. These results indicate that lacustrine-derived XRF element data can be used as a quantitative tool to reconstruct past drought records, and suggest that AMO modulated drought in southern Texas for the last 3000 years. Additional studies using XRF-derived element data as a drought proxy are needed to determine the utility of this proxy in non-playa lacustrine systems.

  9. Ca2+ paradox injury mediated through TRPC channels in mouse ventricular myocytes.

    Science.gov (United States)

    Kojima, Akiko; Kitagawa, Hirotoshi; Omatsu-Kanbe, Mariko; Matsuura, Hiroshi; Nosaka, Shuichi

    2010-12-01

    BACKGROUND AND PURPOSE The Ca(2+) paradox is an important phenomenon associated with Ca(2+) overload-mediated cellular injury in myocardium. The present study was undertaken to elucidate molecular and cellular mechanisms for the development of the Ca(2+) paradox. EXPERIMENTAL APPROACH Fluorescence imaging was performed on fluo-3 loaded quiescent mouse ventricular myocytes using confocal laser scanning microscope. KEY RESULTS The Ca(2+) paradox was readily evoked by restoration of the extracellular Ca(2+) following 10-20 min of nominally Ca(2+)-free superfusion. The Ca(2+) paradox was significantly reduced by blockers of transient receptor potential canonical (TRPC) channels (2-aminoethoxydiphenyl borate, Gd(3+), La(3+)) and anti-TRPC1 antibody. The sarcoplasmic reticulum (SR) Ca(2+) content, assessed by caffeine application, gradually declined during Ca(2+)-free superfusion, which was further accelerated by metabolic inhibition. Block of SR Ca(2+) leak by tetracaine prevented Ca(2+) paradox. The Na(+) /Ca(2+) exchange (NCX) blocker KB-R7943 significantly inhibited Ca(2+) paradox when applied throughout superfusion period, but had little effect when added for a period of 3 min before and during Ca(2+) restoration. The SR Ca(2+) content was better preserved during Ca(2+) depletion by KB-R7943. Immunocytochemistry confirmed the expression of TRPC1, in addition to TRPC3 and TRPC4, in mouse ventricular myocytes. CONCLUSIONS AND IMPLICATIONS These results provide evidence that (i) the Ca(2+) paradox is primarily mediated by Ca(2+) entry through TRPC (probably TRPC1) channels that are presumably activated by SR Ca(2+) depletion; and (ii) reverse mode NCX contributes little to the Ca(2+) paradox, whereas inhibition of NCX during Ca(2+) depletion improves SR Ca(2+) loading, and is associated with reduced incidence of Ca(2+) paradox in mouse ventricular myocytes.

  10. CARINA oxygen data in the Atlantic Ocean

    OpenAIRE

    Stendardo, I.; Gruber, N.; A. Körtzinger

    2009-01-01

    In the CARINA (Carbon dioxide in the Atlantic Ocean) project, a new dataset with many previously unpublished hydrographic data from the Atlantic, Arctic and Southern Ocean was assembled and subjected to careful quality control (QC) procedures. Here, we present the dissolved oxygen measurements in the Atlantic region of the dataset and describe in detail the secondary QC procedures that aim to ensure that the data are internally consistent. This is achieved by a cross-over analysis, i.e. the c...

  11. 77 FR 69596 - Atlantic Highly Migratory Species; Advisory Panel for Atlantic Highly Migratory Species Southeast...

    Science.gov (United States)

    2012-11-20

    ... but not limited to data and models, used in stock assessments for oceanic sharks in the Atlantic Ocean... assessments for oceanic sharks in the Atlantic Ocean, Gulf of Mexico, and Caribbean Sea. While the SEDAR Pool was created specifically for Atlantic oceanic sharks, it may be expanded to include other HMS,...

  12. 76 FR 65700 - Atlantic Highly Migratory Species; Advisory Panel for Atlantic Highly Migratory Species Southeast...

    Science.gov (United States)

    2011-10-24

    ..., used in stock assessments for oceanic sharks in the Atlantic Ocean, Gulf of Mexico, and Caribbean Sea... sharks in the Atlantic Ocean, Gulf of Mexico, and Caribbean Sea. While the SEDAR Pool was created specifically for Atlantic oceanic sharks, it may be expanded to include other HMS, as needed. The...

  13. 75 FR 57698 - Atlantic Highly Migratory Species; Atlantic Billfish Management, White Marlin (Kajikia albidus

    Science.gov (United States)

    2010-09-22

    ... western Atlantic Ocean, white marlin and blue marlin from the North Atlantic Ocean, and longbill spearfish... published an interim rule (63 FR 14030) that increased the minimum size limits for Atlantic blue marlin and... Consolidated HMS FMP (71 FR 58058), which, among other things, included the annual recreational 250 blue...

  14. Climate variability during warm and cold phases of the Atlantic Multidecadal Oscillation (AMO) 1871-2008

    Science.gov (United States)

    Alexander, Michael A.; Halimeda Kilbourne, K.; Nye, Janet A.

    2014-05-01

    An extended reanalysis, a combination of observations and model output, is used to examine the spatial patterns of physical variables associated with the Atlantic Multidecadal Oscillation (AMO) from 1871 to 2008. The results are presented as anomalies during positive and negative phases of the AMO. As in previous studies, during positive (negative) AMO phases the sea surface temperature (SST) is anomalously warm (cold) over most of the North Atlantic, with the exception of the east coast of the United States. The atmospheric patterns, associated with the positive phase of the AMO, include anomalous low pressure over the Atlantic between 20°S and 50°N, cyclonic surface winds around the low, reduced wind speeds over the tropical Atlantic and enhanced precipitation in the eastern tropical Atlantic, with roughly opposite conditions during negative AMO phases. There are, however, substantial differences in the SST and the atmospheric anomalies between periods of the same phase, especially in the extratropics. Correlations between the AMO and air temperature anomalies are positive over much of the globe between 40°S and 50°N, with correlations exceeding 0.6 (~ 95% significance level) over the Maritime Continent and northern rim of the Pacific Ocean. Most of the sea level pressure (SLP) anomalies beyond the Atlantic are not statistically significant.

  15. Tropical climate variability: interactions across the Pacific, Indian, and Atlantic Oceans

    Science.gov (United States)

    Kajtar, Jules B.; Santoso, Agus; England, Matthew H.; Cai, Wenju

    2016-06-01

    Complex interactions manifest between modes of tropical climate variability across the Pacific, Indian, and Atlantic Oceans. For example, the El Niño-Southern Oscillation (ENSO) extends its influence on modes of variability in the tropical Indian and Atlantic Oceans, 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 ocean basin, as well as pairs of ocean basins, is suppressed in turn. We find that Indian Ocean variability has a net damping effect on ENSO and Atlantic Ocean variability, and conversely they each promote Indian Ocean variability. The connection between the Pacific and the Atlantic is most clearly revealed in the absence of Indian Ocean variability. Our model runs suggest a weak damping influence by Atlantic variability on ENSO, and an enhancing influence by ENSO on Atlantic variability.

  16. Diel variation in feeding and movement patterns of juvenile Atlantic cod at offshore wind farms

    Science.gov (United States)

    Reubens, Jan T.; De Rijcke, Maarten; Degraer, Steven; Vincx, Magda

    2014-01-01

    Atlantic cod (Gadus morhua) is a commercially important fish species suffering from overexploitation in the North-East Atlantic. In recent years, their natural environment is being intensively altered by the construction of offshore wind farms in many coastal areas. These constructions form artificial reefs influencing local biodiversity and ecosystem functioning. It has been demonstrated that Atlantic cod is present in the vicinity of these constructions. However, empirical data concerning the diel activity and feeding behaviour of Atlantic cod in the vicinity of these artificial reefs is lacking. Atlantic cod has a flexible diel activity cycle linked to spatio-temporal variations in food availability and predation risk. In this study we integrated acoustic telemetry with stomach content analysis to quantify diel activity and evaluate diel feeding patterns at a windmill artificial reef (WAR) in the Belgian part of the North Sea. Atlantic cod exhibited crepuscular movements related to feeding activity; a 12 h cycle was found and the highest catch rates and stomach fullness were recorded close to sunset and sunrise. It is suggested that the observed diel movement pattern is related to the prey species community and to predation pressure. Foraging at low ambient light levels (i.e. at dusk and dawn) probably causes a trade-off between foraging success and reducing predation pressure. Fish did not leave the area in-between feeding periods. Hence other benefits (i.e. shelter against currents and predators) besides food availability stimulate the aggregation behaviour at the WARs.

  17. Surface Temperature Trends in the Arctic Atlantic Region Over the Last 2,000 Years

    Science.gov (United States)

    Korhola, A.; Hanhijarvi, S.; Tingley, M.

    2013-12-01

    We introduce a new reconstruction method that uses the ordering of all pairs of proxy observations within each record to arrive at a consensus time series that best agrees with all proxy records. By considering only pairwise comparisons, this method, which we call PaiCo, facilitates the inclusion of records with differing temporal resolutions, and relaxes the assumption of linearity to the more general assumption of a monotonically increasing relationship between each proxy series and the target climate variable. We apply PaiCo to a newly assembled collection of high-quality proxy data to reconstruct the mean temperature of the Northernmost Atlantic region, which we call Arctic Atlantic, over the last 2,000 years. The Arctic Atlantic is a dynamically important region known to feature substantial temperature variability over recent millennia, and PaiCo allows for a more thorough investigation of the Arctic Atlantic regional climate as we include a diverse array of terrestrial and marine proxies with annual to multidecadal temporal resolutions. Comparisons of the PaiCo reconstruction to recent reconstructions covering larger areas indicate greater climatic variability in the Arctic Atlantic than for the Arctic as a whole. The Arctic Atlantic reconstruction features temperatures during the Roman Warm Period and Medieval Climate Anomaly that are comparable or even warmer than those of the twentieth century, and coldest temperatures in the middle of the nineteenth century, just prior to the onset of the recent warming trend.

  18. Present-day spreading motion of the mid-Atlantic ridge

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Over a long period of time, the spreading rate of the mid-Atlantic ridge has been ascertained by the geological age of the magnetic stripe laid out oneither side of the mid-ocean ridge in conjunction with the annals of the magnetic reversal history. Is the mid-Atlantic ridge still spreading today? How fast is it moving or are there any changes? All these questions remain unsolved. Basedon the newest ITRF2000 velocity field published by the International Earth Rotation Service (IERS), the contemporary global plate motion model ITRF2000VEL is constructed, independent of any plate model hypothesis. Solutions for relative Euler's vectors of plate pairs as North America-Eurasia, North America- Africa andSouth America-Africa are obtained, implying current spreading rates of the mid-Atlantic ridge. Comparing them with results from the NNR-NUVEL1A model displays the present-day motion characteristics of the mid-Atlantic ridge that the mid-ridge of the South Atlantic, whose spreading is slowing down, spreads faster than the North Atlantic, whose spreading is speeding up.

  19. Tracking the Atlantic Multidecadal Oscillation through the last 8,000 years

    DEFF Research Database (Denmark)

    Knudsen, Mads Faurschou; Seidenkrantz, Marit-Solveig; Jacobsen, B. H.;

    2011-01-01

    Understanding the internal ocean variability and its influence on climate is imperative for society. A key aspect concerns the enigmatic Atlantic Multidecadal Oscillation (AMO), a feature defined by a 60- to 90-year variability in North Atlantic sea-surface temperatures. The nature and origin...... and reject the hypothesis that this climate oscillation was directly forced by periodic changes in solar activity. We therefore conjecture that a quasi-persistent ~55- to 70-year AMO, linked to internal ocean-atmosphere variability, existed during large parts of the Holocene. Our analyses further suggest...... of the AMO is uncertain, and it remains unknown whether it represents a persistent periodic driver in the climate system, or merely a transient feature. Here, we show that distinct, ~55- to 70-year oscillations characterized the North Atlantic ocean-atmosphere variability over the past 8,000 years. We test...

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

    Science.gov (United States)

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

    2005-01-01

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

  1. Hippocampal CA2 activity patterns change over time to a larger extent than between spatial contexts.

    Science.gov (United States)

    Mankin, Emily A; Diehl, Geoffrey W; Sparks, Fraser T; Leutgeb, Stefan; Leutgeb, Jill K

    2015-01-01

    The hippocampal CA2 subregion has a different anatomical connectivity pattern within the entorhino-hippocampal circuit than either the CA1 or CA3 subregion. Yet major differences in the neuronal activity patterns of CA2 compared with the other CA subregions have not been reported. We show that standard spatial and temporal firing patterns of individual hippocampal principal neurons in behaving rats, such as place fields, theta modulation, and phase precession, are also present in CA2, but that the CA2 subregion differs substantially from the other CA subregions in its population coding. CA2 ensembles do not show a persistent code for space or for differences in context. Rather, CA2 activity patterns become progressively dissimilar over time periods of hours to days. The weak coding for a particular context is consistent with recent behavioral evidence that CA2 circuits preferentially support social, emotional, and temporal rather than spatial aspects of memory. PMID:25569350

  2. 有关CA

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ 什么是CA? CA(Certificaton Authority)是认证机构的国际通称,是指对数字证书的申请者发放、管理、取消数字证书的机构.CA的作用是检查证书持有者身份的合法性,并签发证书(在证书上签字),以防证书被伪造或篡改.

  3. 22 CFR 120.31 - North Atlantic Treaty Organization.

    Science.gov (United States)

    2010-04-01

    ... DEFINITIONS § 120.31 North Atlantic Treaty Organization. North Atlantic Treaty Organization (NATO) is..., France, Germany, Greece, Hungary, Iceland, Italy, Latvia, Lithuania, Luxembourg, The Netherlands,...

  4. Mammal occurrence and roadkill in two adjacent ecoregions (Atlantic Forest and Cerrado) in south-western Brazil

    OpenAIRE

    Nilton C. Cáceres; Wellington Hannibal; Dirceu R. Freitas; Edson L. Silva; Cassiano Roman; Janaina Casella

    2010-01-01

    This paper examines the frequencies of mammal roadkill in two adjacent biogeographic ecoregions (Atlantic Forest and Cerrado) of Brazil. Mammals were recorded during a seven-year period and over 3,900 km of roads, in order to obtain data for frequencies of species in habitats (sites) and frequencies of species killed by cars on roads. Sites (n = 80) within ecoregions (Cerrado, n = 57; Atlantic Forest, n = 23) were searched for records of mammals. Species surveyed in the entire region totaled ...

  5. Genetic diversity and biogeographical patterns of Caulerpa prolifera across the Mediterranean and Mediterranean/Atlantic transition zone

    KAUST Repository

    Varela-Álvarez, Elena

    2015-01-11

    Knowledge of spatial patterns of genetic differentiation between populations is key to understanding processes in evolutionary history of biological species. Caulerpa is a genus of marine green algae, which has attracted much public attention, mainly because of the impacts of invasive species in the Mediterranean. However, very little is known about the ecological and evolutionary history of the Mediterranean native Caulerpa prolifera, a species which is currently found at sites distributed worldwide. C. prolifera provides a good model to explore the patterns of genetic diversity at different scales across the Mediterranean and Atlantic area. This study aims to investigate the biogeographical patterns of diversity and differentiation of C. prolifera in the Mediterranean, with special focus on the Mediterranean/Atlantic transition zone. We used two nuclear (ITS rDNA and the hypervariable microsatellite locus CaPr_J2) and one chloroplast (tufA) DNA markers on samples of C. prolifera from its entire range. Analyses of 51 sequences of the cpDNA tufA of C. prolifera, 87 ITS2 sequences and genotypes of 788 ramets of C. prolifera for the locus CaPr_J2 revealed three different biogeographical areas: West Atlantic, East Atlantic and a larger area representing the Mediterranean, the Mediterranean/Atlantic transition zone and a Pacific site (Bali). It was found out that the Mediterranean/Atlantic transition zone is a biogeographical boundary for C. prolifera. A lack of connectivity was revealed between Atlantic and Mediterranean types, and identical sequences found in the Mediterranean and Indo-Pacific suggest either recent gene flow along the Red Sea connection or a possible ancient Indo-Pacific origin.

  6. Chamber formation leads to Mg/Ca banding in the planktonic foraminifer Neogloboquadrina pachyderma

    Science.gov (United States)

    Jonkers, Lukas; Buse, Ben; Brummer, Geert-Jan A.; Hall, Ian R.

    2016-10-01

    Many species of planktonic foraminifera show distinct banding in the intratest distribution of Mg/Ca. This heterogeneity appears biologically controlled and thus poses a challenge to Mg/Ca paleothermometry. The cause of this banding and its relation with chamber formation are poorly constrained and most of what we know about intratest Mg/Ca variability stems from culture studies of tropical, symbiont-bearing foraminifera. Here we present data on the non-spinose, symbiont-barren Neogloboquadrina pachyderma from the subpolar North Atlantic where wintertime mixing removes vertical gradients in temperature and salinity. This allows investigation of biologically controlled Mg/Ca intratest variability under natural conditions. We find that intratest Mg/Ca varies between accounted for.

  7. Eastern Pacific cooling and Atlantic overturning circulation during the last deglaciation.

    Science.gov (United States)

    Kienast, Markus; Kienast, Stephanie S; Calvert, Stephen E; Eglinton, Timothy I; Mollenhauer, Gesine; François, Roger; Mix, Alan C

    2006-10-19

    Surface ocean conditions in the equatorial Pacific Ocean could hold the clue to whether millennial-scale global climate change during glacial times was initiated through tropical ocean-atmosphere feedbacks or by changes in the Atlantic thermohaline circulation. North Atlantic cold periods during Heinrich events and millennial-scale cold events (stadials) have been linked with climatic changes in the tropical Atlantic Ocean and South America, as well as the Indian and East Asian monsoon systems, but not with tropical Pacific sea surface temperatures. Here we present a high-resolution record of sea surface temperatures in the eastern tropical Pacific derived from alkenone unsaturation measurements. Our data show a temperature drop of approximately 1 degrees C, synchronous (within dating uncertainties) with the shutdown of the Atlantic meridional overturning circulation during Heinrich event 1, and a smaller temperature drop of approximately 0.5 degrees C synchronous with the smaller reduction in the overturning circulation during the Younger Dryas event. Both cold events coincide with maxima in surface ocean productivity as inferred from 230Th-normalized carbon burial fluxes, suggesting increased upwelling at the time. From the concurrence of equatorial Pacific cooling with the two North Atlantic cold periods during deglaciation, we conclude that these millennial-scale climate changes were probably driven by a reorganization of the oceans' thermohaline circulation, although possibly amplified by tropical ocean-atmosphere interaction as suggested before. PMID:17051216

  8. EFFLUENT - DISCHARGE DESCRIPTION and Other Data from FIXED PLATFORM and Other Platforms From NW Atlantic (limit-40 W) from 19800529 to 19840609 (NODC Accession 8600070)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Effluent discharge was studied from fixed platform and other platforms from NW Atlantic (limit-40 w) for a period of three years. The trace metal concentrations...

  9. Electrodeposition of Ca Metal in CaCl2-CaO Molten Salt

    Institute of Scientific and Technical Information of China (English)

    GUO; Jun-kang; WANG; Chang-shui; CAO; Long-hao; OUYANG; Ying-gen

    2013-01-01

    To realize the continuouscalciothermic reduction in molten salts,the electrodeposition behavior of Ca metal in CaCl2-CaO molten salt was investigated by cylic voltammetry.The cyclic voltammograms at the scan rate of 100 mV/s are shown in Fig.1.As is shown,the electrodeposition potential of Ca deviated from-1.66 V to-0.97 V after CaO was added to molten CaCl2 and the decomposition of CaO

  10. Isotope analysis reveals foraging area dichotomy for atlantic leatherback turtles.

    Directory of Open Access Journals (Sweden)

    Stéphane Caut

    Full Text Available BACKGROUND: The leatherback turtle (Dermochelys coriacea has undergone a dramatic decline over the last 25 years, and this is believed to be primarily the result of mortality associated with fisheries bycatch followed by egg and nesting female harvest. Atlantic leatherback turtles undertake long migrations across ocean basins from subtropical and tropical nesting beaches to productive frontal areas. Migration between two nesting seasons can last 2 or 3 years, a time period termed the remigration interval (RI. Recent satellite transmitter data revealed that Atlantic leatherbacks follow two major dispersion patterns after nesting season, through the North Gulf Stream area or more eastward across the North Equatorial Current. However, information on the whole RI is lacking, precluding the accurate identification of feeding areas where conservation measures may need to be applied. METHODOLOGY/PRINCIPAL FINDINGS: Using stable isotopes as dietary tracers we determined the characteristics of feeding grounds of leatherback females nesting in French Guiana. During migration, 3-year RI females differed from 2-year RI females in their isotope values, implying differences in their choice of feeding habitats (offshore vs. more coastal and foraging latitude (North Atlantic vs. West African coasts, respectively. Egg-yolk and blood isotope values are correlated in nesting females, indicating that egg analysis is a useful tool for assessing isotope values in these turtles, including adults when not available. CONCLUSIONS/SIGNIFICANCE: Our results complement previous data on turtle movements during the first year following the nesting season, integrating the diet consumed during the year before nesting. We suggest that the French Guiana leatherback population segregates into two distinct isotopic groupings, and highlight the urgent need to determine the feeding habitats of the turtle in the Atlantic in order to protect this species from incidental take by

  11. The Indian Ocean Dipole's influence on Atlantic tropical cyclone activity

    Science.gov (United States)

    Marinaro, Alan Joseph

    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 Atlantic tropical cyclone activity (Year +1). The autumn Indian Ocean 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 Atlantic 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 Atlantic 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 Atlantic tropical cyclonesn.

  12. Reevaluation of mid-Pliocene North Atlantic sea surface temperatures

    Science.gov (United States)

    Robinson, Marci M.; Dowsett, Harry J.; Dwyer, Gary S.; Lawrence, Kira T.

    2008-01-01

    Multiproxy temperature estimation requires careful attention to biological, chemical, physical, temporal, and calibration differences of each proxy and paleothermometry method. We evaluated mid-Pliocene sea surface temperature (SST) estimates from multiple proxies at Deep Sea Drilling Project Holes 552A, 609B, 607, and 606, transecting the North Atlantic Drift. SST estimates derived from faunal assemblages, foraminifer Mg/Ca, and alkenone unsaturation indices showed strong agreement at Holes 552A, 607, and 606 once differences in calibration, depth, and seasonality were addressed. Abundant extinct species and/or an unrecognized productivity signal in the faunal assemblage at Hole 609B resulted in exaggerated faunal-based SST estimates but did not affect alkenone-derived or Mg/Ca–derived estimates. Multiproxy mid-Pliocene North Atlantic SST estimates corroborate previous studies documenting high-latitude mid-Pliocene warmth and refine previous faunal-based estimates affected by environmental factors other than temperature. Multiproxy investigations will aid SST estimation in high-latitude areas sensitive to climate change and currently underrepresented in SST reconstructions.

  13. Atlantic hurricane response to geoengineering

    Science.gov (United States)

    Moore, John; Grinsted, Aslak; Ji, Duoying; Yu, Xiaoyong; Guo, Xiaoran

    2015-04-01

    Devastating Atlantic hurricanes are relatively rare events. However their intensity and frequency in a warming world may rapidly increase - perhaps by a factor of 5 for a 2°C mean global warming. Geoengineering by sulphate aerosol injection preferentially cools the tropics relative to the polar regions, including the hurricane main development region in the Atlantic, suggesting that geoengineering may be an effective method of controlling hurricanes. We examine this hypothesis using 6 Earth System Model simulations of climate under the GeoMIP G3 and G4 schemes that use aerosols to reduce the radiative forcing under the RCP4.5 scenario. We find that although temperatures are ameliorated by geoengineering, the numbers of storm surge events as big as that caused the 2005 Katrina hurricane are only slightly reduced compared with no geoengineering. As higher levels of sulphate aerosol injection produce diminishing returns in terms of cooling, but cause undesirable effects in various regions, it seems that stratospheric aerosol geoengineering is not an effective method of controlling hurricane damage.

  14. Dissolution of calcium carbonate: observations and model results in the North Atlantic

    Directory of Open Access Journals (Sweden)

    K. Friis

    2006-10-01

    Full Text Available We investigate the significance of in situ dissolution of calcium carbonate above its saturation horizons. The study relies on observations from the open subpolar North Atlantic [sNA] and on a 3-D biogeochemical model. The sNA is particularly well suited for observation-based detections of in situ, i.e. shallow depth CaCO3 dissolution [SDCCD] as it is a region of high CaCO3 production, deep CaCO3 saturation horizons, and precisely-defined pre-formed alkalinity. Based on the analysis of a comprehensive alkalinity data set we find that SDCCD does not appear to be a significant process in the open sNA. The results from the model support the observational findings and do not indicate a significant need of SDCCD to explain observed patterns of alkalinity in the North Atlantic. Instead our investigation points to the importance of mixing processes for the redistribution of alkalinity from dissolution of CaCO3 from below its saturation horizons. However, mixing has recently been neglected for a number of studies that called for SDCCD in the sNA and on global scale.

  15. C.A. Nothardbiblioteek

    Directory of Open Access Journals (Sweden)

    J. Swart

    1988-09-01

    Full Text Available As instructed by the Central Board of the South African Nursing Association during 1985, an investigation was launched into the function of the C.A. Not hard Library, namely to provide optimal information to members. The underlying philosophy concerned with the establishment of the library was to provide a service which is not available elsewhere. The investigation revealed however, that various training institutions in the country meet this need. As a result of the findings, as presented in the article, the C.A. Northard Library was closed on 1 December 1985 as a lending library. A unique Nursing reference library is being established in its place, with the emphasis in the future on the S. A. Nursing Association’s role in the promotion of Nursing research.

  16. Sulfide capacities of CaO-CaF2-CaCl2 melts

    Science.gov (United States)

    Simeonov, Simeon; Sakai, Toshihiko; Maeda, Masafumi

    1992-06-01

    The sulfide capacityC_{s^{2 - } } = ({text{pct S}}^{{text{2 - }}} )(p_{{text{O}}_{text{2}} } /p_{{text{S}}_{text{2}} } )^{1/2} ) of CaO-CaF2-CaCl2 slag was determined at temperatures from 1000 °C to 1300 °C by equilibrating molten slag, molten silver, and CO-CO2-Ar gas mixture. The sulfide capacity increases with replacing CaCl2 by CaF2 in slags of constant CaO contents. The sulfide capacity also increases with increasing temperature as well as with increasing CaO content at a constant ratio of CaF2/CaCl2 of unity. A linear relationship between the sulfide capacity and carbonate capacity in literature was observed on a logarithmic scale.

  17. Atlantic surfclam connectivity within the Middle Atlantic Bight: Mechanisms underlying variation in larval transport and settlement

    Science.gov (United States)

    Zhang, Xinzhong; Munroe, Daphne; Haidvogel, Dale; Powell, Eric N.

    2016-05-01

    Larval transport and settlement have been shown in various studies to be essential in determining population abundance and connectivity for benthic invertebrates. This transport is influenced by both the physical environment and biological behavior. The Atlantic surfclam, Spisula solidissima, is a commercially important benthic invertebrate fishery species along the U.S northeastern coast. In this study, a physical circulation model is coupled to a surfclam larval model to investigate the dynamics of larval transport and settlement within the Middle Atlantic Bight (MAB) shelf in 2006. The main physical mechanisms causing variability in larval transport and settlement are also examined. Model results show that surfclam larvae released from July to early October experience relatively larger settlement rates, due to higher average temperatures experienced by larvae. Larval along-shore transport exhibits a mean down-coast pattern following the coastal current from the northeast to the southwest, with most high-frequency (period of 2-10 days) variations caused by fluctuations in the along-shore surface wind stress, and with seasonal variations speculated to be driven mainly by changes in the across-shelf density gradient. Larval across-shelf movement is highly correlated with the along-shore surface wind stress mediated by coastal upwelling and downwelling episodes, but the correlation is further dependent on the vertical distribution of the larvae, particularly their position relative to the thermocline. Most surfclam larvae released from the Middle Atlantic shelf stay below the thermocline and experience a net onshore transport during the summer-stratified season when upwelling-favorable wind forcing dominates. A proposed critical value of water temperature at the thermocline successfully regulates the observed patterns of vertical distribution of surfclam larvae and their across-shelf movement off the New Jersey and South Virginia shelves; that is, when the water

  18. Northern tropical Atlantic climate since late Medieval times from Northern Caribbean coral geochemistry

    Science.gov (United States)

    Kilbourne, K. H.; Xu, Y.

    2015-12-01

    Paleoclimate reconstructions of different global climate modes over the last 1000 years provide the basis for testing the relative roles of forced and unforced variability climate system, which can help us improve projections of future climate change. The Medieval Climate Anomaly (MCA) has been characterized by a combination of persistent La Niña-like conditions, a positive North Atlantic Oscillation (+NAO), and increased Atlantic Meridional Overturning Circulation (AMOC). The northern tropical Atlantic is sensitive to each of these climate patterns, but not all of them have the same regional fingerprint in the modern northern tropical Atlantic. The relative influence of different processes related to these climate patterns can help us better understand regional responses to climate change. The regional response of the northern tropical Atlantic is important because the tropical Atlantic Ocean is a large source of heat and moisture to the global climate system that can feedback onto global climate patterns. This study presents new coral Sr/Ca and δ18O data from the northern tropical Atlantic (Anegada, British Virgin Islands). Comparison of the sub-fossil corals that grew during the 13th and 14th Centuries with modern coral geochemical data from this site indicates relatively cooler mean conditions with a decrease in the oxygen isotopic composition of the water consistent with lower salinities. Similar average annual cycles between modern and sub-fossil Sr/Ca indicate no change in seasonal temperature range, but a difference in the relative phasing of the δ18O seasonal cycles indicates that the fresher mean conditions may be due to a more northerly position of the regional salinity front. This localized response is consistent with some, but not all of the expected regional responses to a La Niña-like state, a +NAO state, and increased AMOC. Understanding these differences can provide insight into the relative importance of advection versus surface fluxes for

  19. Calcium-ammonium exchange experiments on clay minerals using a (45)Ca tracer technique in marine pore water.

    Science.gov (United States)

    Ockert, Charlotte; Wehrmann, Laura M; Kaufhold, Stephan; Ferdelman, Tim G; Teichert, Barbara M A; Gussone, Nikolaus

    2014-01-01

    Understanding cation exchange processes is important for evaluating early diagenetic and synsedimentary processes taking place in marine sediments. To quantify calcium (Ca) exchange and Ca-ammonium exchange in a seawater environment, we performed experiments with a radioactive (45)Ca tracer on clay mineral standards (Fithian illite, montmorillonite and kaolinite) and marine sediments from the North Atlantic Integrated Ocean Drilling Program Site U1306A in artificial seawater (ASW). The results show that equilibrium during the initial attachment of Ca as well as the exchange of Ca by [Formula: see text] is attained in less than 2 min. On average 8-20% of the exchangeable sites of the clay minerals were occupied by Ca in a seawater medium. The conditional selectivity coefficient, describing the [Formula: see text] exchange in ASW is mineral specific and it was determined to be 0.07 for montmorillonite, 0.05 for a natural marine sediment and 0.013 for Fithian illite.

  20. Ecosystem Alterations and Species Range Shifts: An Atlantic-Mediterranean Cephalaspidean Gastropod in an Inland Egyptian Lake

    Science.gov (United States)

    Malaquias, Manuel António E.

    2016-01-01

    The eastern Atlantic and Mediterranean marine Cephalaspidea gastropod Haminoea orbignyana was collected from Lake Qarun (Fayoum, Egypt), a landlocked lake that has undergone a shift from freshwater to estuarine conditions in the past 100 years. Species identity was confirmed by both morphological (anatomical dissection and scanning electron microscopy) and molecular methods (COI gene phylogeny). Observations suggested a robust population of H. orbignyana in the lake with a density of ca. 64 individuals/m2 and ca. 105 egg masses/m2 during surveys conducted in the summer of 2013. The vast majority of snails and egg masses were found under rocks. Observations of egg masses in the lab showed a gradual change from whitish to yellow-green as the eggs matured and the release of veliger larvae alone after about a week. Although adult cephalaspideans readily consumed filamentous red and green algae, and cyanobacteria, laboratory trials showed that they consumed significantly more of the red alga Ceramium sp., than of the green alga Cladophora glomerata, with consumption of Oscillatoria margaritifera being similar to those on the two algae. When grown on these resources for 16 days, H. orbignyana maintained their mass on the rhodophyte and cyanobacterium, but not in starvation controls. No cephalaspideans grew over the course of this experiment. Lake Qarun has been periodically restocked with Mediterranean fishes and prawns since the 1920s to maintain local fisheries, which represents a possible route of colonization for H. orbignyana. Yet, based on literature records, it seems more likely that invasion of the lake by this gastropod species has occurred only within the last 20 years. As human activities redistribute species through direct and indirect means, the structure of the community of this inland lake has become unpredictable and the long-term effects of these recent introductions are unknown. PMID:27248835

  1. Ecosystem Alterations and Species Range Shifts: An Atlantic-Mediterranean Cephalaspidean Gastropod in an Inland Egyptian Lake.

    Science.gov (United States)

    Cruz-Rivera, Edwin; Malaquias, Manuel António E

    2016-01-01

    The eastern Atlantic and Mediterranean marine Cephalaspidea gastropod Haminoea orbignyana was collected from Lake Qarun (Fayoum, Egypt), a landlocked lake that has undergone a shift from freshwater to estuarine conditions in the past 100 years. Species identity was confirmed by both morphological (anatomical dissection and scanning electron microscopy) and molecular methods (COI gene phylogeny). Observations suggested a robust population of H. orbignyana in the lake with a density of ca. 64 individuals/m2 and ca. 105 egg masses/m2 during surveys conducted in the summer of 2013. The vast majority of snails and egg masses were found under rocks. Observations of egg masses in the lab showed a gradual change from whitish to yellow-green as the eggs matured and the release of veliger larvae alone after about a week. Although adult cephalaspideans readily consumed filamentous red and green algae, and cyanobacteria, laboratory trials showed that they consumed significantly more of the red alga Ceramium sp., than of the green alga Cladophora glomerata, with consumption of Oscillatoria margaritifera being similar to those on the two algae. When grown on these resources for 16 days, H. orbignyana maintained their mass on the rhodophyte and cyanobacterium, but not in starvation controls. No cephalaspideans grew over the course of this experiment. Lake Qarun has been periodically restocked with Mediterranean fishes and prawns since the 1920s to maintain local fisheries, which represents a possible route of colonization for H. orbignyana. Yet, based on literature records, it seems more likely that invasion of the lake by this gastropod species has occurred only within the last 20 years. As human activities redistribute species through direct and indirect means, the structure of the community of this inland lake has become unpredictable and the long-term effects of these recent introductions are unknown. PMID:27248835

  2. Laser Ablation Trace Element Analysis of Modern and Fossil Desmophyllum dianthus from Norfolk and Baltimore Canyons in Mid-Atlantic Ocean

    Science.gov (United States)

    Schoemann, M.; Roark, B.; Fallon, S.; Eggins, S.; Kinsley, L.; Prouty, N.

    2015-12-01

    Deep-sea cup corals are a promising archive for paleoceanographic reconstructions as they are globally distributed with some fossil specimens living throughout the Holocene and into the Last Glacial period. Here we explore the utility of using laser ablation (LA)- ICP-MS to measure the trace elements and δ11B in solitary scleractinian, cup corals, Desmophyllum dianthus collected in Norfolk and Baltimore Canyons from the Mid-Atlantic Ocean. Twelve modern and twenty-six sub-fossil D. dianthus, were collected between a depth range of 400m - 1400m with ambient seawater pH range of 7.89 - 8.00. Modern seawater column chemistry including radiocarbon, nutrients, total alkalinity and particulate trace elements were measured to calibrate geochemical proxies in the live specimens. Radiocarbon measurements indicate sub-fossil specimens lived as long ago as 800 years. A suite of trace elements including P/Ca, Ba/Ca, and U/Ca were analyzed to reconstruct nutrient changes and carbonate ion concentrations. Using previously published calibration equations, modern coral P/Ca ratios yield dissolved inorganic P values of 0.24 - 1.70 μmol/L in line with measured values of 0.1-2.5 μmol/L in the water column. In addition, Ba/Ca (nutrients) yield dissolved Ba values of 25-137 ±16 nmol/kg and U/Ca results yield carbonate ion concentrations of 40-129 ±29 μmol/kg, which are both consistent with previously published work. This study represents the first ever LA-ICP-MS measurements of δ11B using modern and sub-fossil D. dianthus where the modern corals averaged δ11B=18.15±0.01‰. These results are similar to previously published solution ICP-MS results, but using published pH-δ11B calibration equation yields higher pH values than in-situ pH values suggesting future modern calibration work is necessary. Overall, these results show promise for using sub-fossil D. dianthus to reconstruct biogeochemical processes at intermediate and deep waters in Norfolk and Baltimore Canyons.

  3. PARTITIONING OF PLUVIAL PRECIPITATION IN A WATERSHED OCCUPIED BY ATLANTIC FOREST IN MANTIQUEIRA RANGE, MG STATE

    Directory of Open Access Journals (Sweden)

    Léo Fernandes Ávila

    2014-09-01

    Full Text Available http://dx.doi.org/10.5902/1980509815739The analyze of pluvial precipitation and its interaction on the different hydrologic cycle phases in forested watersheds are essential in order to water balance characterization due to its relevant participation in the hydrological processes and to its spatial-temporal variability as function of edaphic, topographic, climatic and vegetation elements. Due to heterogeneity of Atlantic Forest associated to temporal and spatial variability of pluvial precipitation regime, the study of mechanisms that allow describing and linking the hydrological cycle elements are very important. This way, the objective of this study was to analyze the partitioning of pluvial precipitation at a micro-catchment entirely occupied by Atlantic Forest remnant, in Mantiqueira Range, during 2009/2010 and 2010/2011 hydrological years, relating it with the seasonal evolution of this ecosystem which was monitored by the application of normalized difference vegetation indexes (NDVI. It was observed greater percentage of internal pluvial precipitation during the periods with less rainfall. It was also verified greater water storage capacity of the Atlantic Forest’s canopy throughout rainy season. Yet, a plausible correlation was obtained between water storage capacity of Atlantic Forest and the regeneration of vegetation demonstrated by NDVI what can be associated to the processes responsible for Atlantic Forest’s growth.

  4. What controls early or late onset of tropical North Atlantic hurricane season?

    Science.gov (United States)

    Zuo, Heng; Li, Tim; Liu, Jia; Peng, Melinda

    2016-06-01

    The occurrence of first hurricane in early summer signifies the onset of an active Atlantic hurricane season. The interannual variation of this hurricane onset date is examined for the period 1979-2013. It is found that the onset date has a marked interannual variation. The standard deviation of the interannual variation of the onset day is 17.5 days, with the climatological mean onset happening on July 23. A diagnosis of tropical cyclone (TC) genesis potential index (GPI) indicates that the major difference between an early and a late onset group lies in the maximum potential intensity (MPI). A further diagnosis of the MPI shows that it is primarily controlled by the local SST anomaly (SSTA). Besides the SSTA, vertical shear and mid-tropospheric relative humidity anomalies also contribute significantly to the GPI difference between the early and late onset groups. It is found that the anomalous warm (cold) SST over the tropical Atlantic, while uncorrelated with the Niño3 index, persists from the preceding winter to concurrent summer in the early (late) onset group. The net surface heat flux anomaly always tends to damp the SSTA, which suggests that ocean dynamics may play a role in maintaining the SSTA in the tropical Atlantic. The SSTA pattern with a maximum center in northeastern tropical Atlantic appears responsible for generating the observed wind and moisture anomalies over the main TC development region. A further study is needed to understand the initiation mechanism of the SSTA in the Atlantic.

  5. Atmospheric multidecadal variations in the North Atlantic realm: proxy data, observations, and atmospheric circulation model studies

    Directory of Open Access Journals (Sweden)

    K. Grosfeld

    2007-01-01

    Full Text Available We investigate the spatial and temporal characteristics of multidecadal climate variability in the North Atlantic realm, using observational data, proxy data and model results. The dominant pattern of multidecadal variability of SST depicts a monopolar structure in the North Atlantic during the instrumental period with cold (warm phases during 1900–1925 and 1970–1990 (1870–1890 and 1940–1960. Two atmospheric general circulation models of different complexity forced with global SST over the last century show SLP anomaly patterns from the warm and cold phases of the North Atlantic similar to the corresponding observed patterns. The analysis of a sediment core from Cariaco Basin, a coral record from the northern Red Sea, and a long-term sea level pressure (SLP reconstruction reveals that the multidecadal mode of the atmospheric circulation characterizes climate variability also in the pre-industrial era. The analyses of SLP reconstruction and proxy data depict a persistent atmospheric mode at least over the last 300 years, where SLP shows a dipolar structure in response to monopolar North Atlantic SST, in a similar way as the models' responses do. The combined analysis of observational and proxy data with model experiments provides an understanding of multidecadal climate modes during the late Holocene. The related patterns are useful for the interpretation of proxy data in the North Atlantic realm.

  6. Atmospheric multidecadal variations in the North Atlantic realm: proxy data, observations, and atmospheric circulation model studies

    Directory of Open Access Journals (Sweden)

    K. Grosfeld

    2006-08-01

    Full Text Available We investigate the spatial and temporal characteristics of multidecadal climate variability in the North Atlantic realm, using observational data, proxy data and model results. The dominant pattern of multidecadal variability of SST depicts a monopolar structure in the North Atlantic during the instrumental period with cold (warm phases during 1900–1925 and 1970–1990 (1870–1890 and 1940–1960. Two atmospheric general circulation models of different complexity forced with global SST over the last century show SLP anomaly patterns from the warm and cold phases of the North Atlantic similar to the corresponding observed patterns. The analysis of a sediment core from Cariaco Basin, a coral record from the northern Red Sea, and a long-term sea level pressure (SLP reconstruction reveals that the multidecadal mode of the atmospheric circulation characterizes climate variability also in the pre-industrial era. The analyses of SLP reconstruction and proxy data depict a persistent atmospheric mode at least over the last 300 years, where SLP shows a dipolar structure in response to monopolar North Atlantic SST, in a similar way as the models' responses do. The combined analysis of observational and proxy data with model experiments provides an understanding of multidecadal climate modes during the late Holocene. The related patterns are useful for the interpretation of proxy data in the North Atlantic realm.

  7. Retracing diagenetic processes in marine porewaters using Ca isotopes

    Science.gov (United States)

    Ockert, C.; Teichert, B. M.; Kaufhold, S.; Gussone, N. C.

    2012-12-01

    Calcium (Ca) isotope ratios of marine organic and inorganic mineral precipitates are used to monitor changes in the oceanic Ca-budget and in paleo-temperature, and serve as a proxy for the trophic level of organisms in the food chain (c.f. Skulan et al., 1997; Zhu et al., 1998). However, during interaction between sediments and porewater, the Ca isotopic composition of marine porewaters might be shifted, bearing the potential to alter the Ca isotope proxy records. While processes, such as partial dissolution of calcareous shells and carbonate recrystallization have been studied (Fantle and DePaolo, 2007; Turchyn and DePaolo 2011), other diagenetic processes such as ion exchange with clay minerals have not been taken into account while studying Ca isotope profiles of porewaters. Nevertheless, first experiments and the investigation of natural porewaters indicate that this process has a significant effect on the Ca isotope composition in marine porewaters. Laboratory experiments aimed to determine if Ca isotope fractionation occurs during Ca adsorption and exchange with ammonium on clay minerals. The results show that Ca adsorption in a seawater environment is associated with fractionation, where light Ca is preferably adorbed. The addition of ammonium to the experimental set up caused partial release of Ca accompanied by isotope fractionation. Based on the results of the experiments, model calculations tested the impact of varying clay mineral type, content and sediment porosity, revealing that ion exchange processes with clay minerals predominantly shift the porewater signal to lighter values. This is in agreement with observations by Teichert et al. (2009), who found a correlation of ammonium-concentration and δ44/40Ca ratios in the porewater of drill core samples from the Cascadia accretionary margin (ODP Leg 204). Calcium isotope ratios of natural marine porewaters of three sites in the North Atlantic (IODP Expedition 303) show that the correlation between

  8. Temperature fluctuations in the Atlantic Ocean

    International Nuclear Information System (INIS)

    The article discusses the temperature fluctuations in connection with drought in Africa, the climate in North America, the European heat waves and the frequent tropical hurricanes in the Atlantic Ocean. Problems with climate modelling and some pollution aspects are mentioned

  9. Atlantic Marine Mammal Assessment Vessel Surveys

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data sets are a compilation of large vessel surveys for marine mammal stock assessments in South Atlantic (Florida to Maryland) waters from 1994 to the...

  10. Atlantic energy and the strategic outlook

    Directory of Open Access Journals (Sweden)

    Paul Isbell

    2013-09-01

    Full Text Available Sweeping changes are beginning to transform energy scenarios around the world. The gas revolution, a renaissance in petroleum technology and exploration, and a chaotic but powerful movement toward the goal of low-carbon economies are three of the principal energy trends currently interacting with structural changes in the geo-economics of the Atlantic world to present new perspectives and opportunitiesfor the diverse actors in the ‘Atlantic Basin’. This article explores how changes in the energy landscape are contributing to a reassessment of the strategic horizon. The potential impacts of the shale revolution, deep-offshore oil, biofuels and other modern renewable energies on the geopolitics of the Atlantic Basin will be assessed, and the hypothesis that an Atlantic Basin energy system is now taking shape will be evaluated, along with an analysis of anticipated impacts.

  11. Northwest Atlantic Regional Climatology (NCEI Accession 0155889)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — To provide an improved oceanographic foundation and reference for multi-disciplinary studies of the Northwest Atlantic Ocean, NCEI Regional Climatology Team...

  12. Ocean science: Vagaries of Atlantic overturning

    Science.gov (United States)

    Haine, Thomas W. N.

    2016-07-01

    A weakening of the Atlantic meridional overturning circulation has emerged from noise after years of painstaking measurements. Three independent lines of evidence suggest that an anthropogenic influence on this overturning is not yet detectable.

  13. Atlantic NAD 83 Continental Shelf Boundary (CSB)

    Data.gov (United States)

    Bureau of Ocean Energy Management, Department of the Interior — This data set contains Continental Shelf Boundary (CSB) lines in ESRI shapefile format for the BOEM Atlantic Region. The CSB defines the seaward limit of federally...

  14. Atlantic NAD 83 SLA Baseline Tangents

    Data.gov (United States)

    Bureau of Ocean Energy Management, Department of the Interior — This data set contains baseline tangent lines in ArcGIS shapefile format for the BOEM Atlantic Region. Baseline tangent lines are typically bay or river closing...

  15. Atlantic NAD 83 SLA Baseline Points

    Data.gov (United States)

    Bureau of Ocean Energy Management, Department of the Interior — This data set contains baseline points in ArcGIS shapefile format for the BOEM Atlantic Region. Baseline points are the discrete coordinate points along the...

  16. Atlantic Sharpnose Shark Reproductive Biology Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Reproductive data from Atlantic sharpnose sharks were collected from specimens captured throughout the northern Gulf of Mexico on various research vessels. Data...

  17. North Atlantic Coastal Plain aquifer system

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set represents the extent of the North Atlantic Coastal Plain aquifer system in North Carolina, Virginia, Maryland, Deleware, and New Jersey.

  18. Atlantic Surfclam and Ocean Quahog Survey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The standardized NEFSC Atlantic Surfclam and Ocean Quahog Survey has covered an area from Cape Hatteras to Georges Bank. The survey was conducted every two or three...

  19. Younger Dryas thermohaline circulation in the N-Atlantic: Irminger Sea versus Norwegian Sea Basin

    Science.gov (United States)

    Kuijpers, Antoon; Seidenkrantz, Marit-Solveig; Luise Knudsen, Karen; Knutz, Paul C.; Sicre, Marie-Alexandrine; Andresen, Camilla S.; Pearce, Christof

    2016-04-01

    Oceanographic observations from the early 1990's show a marked cooling and freshening of the Nordic Seas due to eastward expansion of East Greenland Current derived Polar Waters under influence of strong zonal atmospheric circulation(1). For the cold Younger Dryas (YD) period, ca 12,900 - 11,600 years ago, the impact of Northern Hemisphere late glacial melt water pulses on N- Atlantic thermohaline circulation has been discussed as a likely mechanism for cooling. Melt water discharge sources have been a matter of much debate, but recent evidence point to important melt water pulses emanating from the Arctic region (2, e.g. MacKenzie Valley discharge). The largest volume of these fresh water masses reached the North Atlantic via Fram Strait, less through the Canadian archipelago. During preceding Bølling-Allerød warming, the size of the Laurentide Ice Sheet may have been still large enough to have influenced atmospheric planetary waves resulting in a more zonal Atlantic jet axis(3). In addition, Northern Hemisphere high summer insolation favored a northward displaced west wind belt forcing surface waters away from the Greenland coast. Hence, in analogue to recent observations, ice-loaded meltwater masses in the western Greenland Sea were forced eastward, creating a pool of cold,low salinity (ice-loaded) surface water masses in the Norwegian Sea(4), while transport of cold Polar Water via Denmark Strait to the Irminger Sea would be suppressed. Our own sediment core data from offshore Iceland, Greenland and Davis Strait(5,6,7)together with results from lake studies in southern Greenland(8) point to an active Irminger Current and well-developed Irminger Sea Water subsurface transport towards Davis Strait. Subsequent incorporation of the latter water mass into the south-flowing Labrador Current may have contributed to tidewater glacier melting in eastern Canada and eventually triggering of the H0 meltwater pulse. The sediment core data indicate Irminger Sea deep

  20. Lost fishing gear and litter at Gorringe Bank (NE Atlantic)

    Science.gov (United States)

    Vieira, Rui P.; Raposo, Isabel P.; Sobral, Paula; Gonçalves, Jorge M. S.; Bell, Katherine L. C.; Cunha, Marina R.

    2015-06-01

    Studies concerning marine litter have received great attention over the last several years by the scientific community mainly due to their ecological and economic impacts in marine ecosystems, from coastal waters to the deep ocean seafloor. The distribution, type and abundance of marine litter in Ormonde and Gettysburg, the two seamounts of Gorringe Bank, were analyzed from photo and video imagery obtained during ROV-based surveys carried out at 60-3015 m depths during the E/V Nautilus cruise NA017. Located approximately 125 nm southwest of Portugal, Gorringe Bank lays at the crossroad between the Atlantic and the Mediterranean and is therefore characterized by an intense maritime traffic and fishing activities. The high frequency of lost or discarded fishing gear, such as cables, longlines and nets, observed on Gorringe Bank suggests an origin mostly from fishing activities, with a clear turnover in the type of litter (mostly metal, glass and to a much lesser extent, plastic) with increasing depth. Litter was more abundant at the summit of Gorringe Bank (ca. 4 items·km- 1), decreasing to less than 1 item·km- 1 at the flanks and to ca. 2 items·km- 1 at greater depths. Nevertheless, litter abundance appeared to be lower than in continental margin areas. The results presented herein are a contribution to support further actions for the conservation of vulnerable habitats on Gorringe Bank so that they can continue contributing to fishery productivity in the surrounding region.

  1. Atlantic forcing of Amazonian climates in the last ice age

    Science.gov (United States)

    Bush, M. B.; Mosblech, N.; Valencia, B. G.; Hodell, D. A.; Gosling, W. D.; Van Calsteren, P. W.; Thomas, L. E.; Curtis, J. H.

    2011-12-01

    An absence of study sites means that the relative influence of orbitally driven presession cycles and millenial scale variability upon ice-age Amazonian precipitation is unknown. Here we present a continuous isotopic (δO18 and C13) record spanning the period from ~93-8 ka, from the aseasonal forests of Amazonian Ecuador. The variability in δO18 depletion is probably related to the relative strength of evapotranspired moisture (less depleted) and tropical Atlantic moisture carried across the basin by the South American Low Level Jet (more depleted). Times of strengthened South American Low Level Jet probably correspond to increased overall moisture availability and hence elevated precipitation. The occurrence of markedly depleted δO18 signatures during Heinrich events suggests a strong influence of the Atlantic Ocean on this system, and that these northern hemispheric stadials induced wet episodes in western Amazonia. Weakening of the Atlantic Meridional Overturning Circulation (AMOC) has been suggested to strengthen the South American Low Level Jet. The isotopic records reveal strong cohesion with previously published records from southern Brazil. A precessional influence amplifies the north Atlantic signal between c. 93 ka and 50 ka. However, after c. 50 ka the precessional signal weakens, perhaps sugesting that at a critical size the Laurentide ice mass exerted a strong influence on Neotropical climates suppressing the weaker forcing associated with precession. Contrary to long-standing expectation, the Last Glacial Maximum (21 ± 2 ka) does not stand out as time of aridity in this record. However, between c. 35 ka and 18 ka there is a drift toward less depleted rainfall. One hypothesis to account for this observation is that the climate was becoming more seasonal as the Intertropical Convergence Zone (ITCZ) formed further south than its modern location. The resulting weakened influence of the South American Summer Monsoon (SASM) would probably reduce wet

  2. Diet and metazoan parasites of juvenile and subadult silver scabbard fish, Lepidopus caudatus, from the Great Meteor Seamount (North Atlantic)

    OpenAIRE

    Klimpel, S.; Rückert, S; Piatkowski, Uwe; Palm, H. W.; Hanel, Reinhold

    2006-01-01

    Silver scabbard fish Lepidopus caudatus (Euphrasen, 1788) (Trichiuridae) from the Great Meteor Seamount (GMS) in the central eastern Atlantic were studied for diet composition and metazoan parasites. A total of 36 specimens with lengths between 39.1 and 52.2 cm were sampled, which had taken 14 different prey items belonging to 4 major taxonomic groups (Chaetognatha, Crustacea, Mollusca and Teleostei). The most abundant prey organisms were Myctophidae and Euphausiacea, followed by Copepoda (Ca...

  3. Impacts of Indian and Atlantic oceans on ENSO in a comprehensive modeling framework

    Science.gov (United States)

    Terray, Pascal; Masson, Sébastien; Prodhomme, Chloé; Roxy, Mathew Koll; Sooraj, K. P.

    2016-04-01

    The impact of the Indian and Atlantic oceans variability on El Niño-Southern-Oscillation (ENSO) phenomenon is investigated through sensitivity experiments with the SINTEX-F2 coupled model. For each experiment, we suppressed the sea surface temperature (SST) variability in either the Indian or Atlantic oceans by applying a strong nudging of the SST toward a SST climatology computed either from a control experiment or observations. In the sensitivity experiments where the nudging is done toward a control SST climatology, the Pacific mean state and seasonal cycle are not changed. Conversely, nudging toward an observed SST climatology in the Indian or Atlantic domain significantly improves the mean state and seasonal cycle, not only in the nudged domain, but also in the whole tropics. These experiments also demonstrate that decoupling the Indian or Atlantic variability modifies the phase-locking of ENSO to the annual cycle, influences significantly the timing and processes of ENSO onset and termination stages, and, finally, shifts to lower frequencies the main ENSO periodicities. Overall, these results suggest that both the Indian and Atlantic SSTs have a significant damping effect on ENSO variability and promote a shorter ENSO cycle. The reduction of ENSO amplitude is particularly significant when the Indian Ocean is decoupled, but the shift of ENSO to lower frequencies is more pronounced in the Atlantic decoupled experiments. These changes of ENSO statistical properties are related to stronger Bjerknes and thermocline feedbacks in the nudged experiments. During the mature phase of El Niño events, warm SST anomalies are found over the Indian and Atlantic oceans in observations or the control run. Consistent with previous studies, the nudged experiments demonstrate that these warm SSTs induce easterly surface wind anomalies over the far western equatorial Pacific, which fasten the transition from El Niño to La Niña and promote a shorter ENSO cycle in the control

  4. Seasonal Variability of South Atlantic Central Water

    Science.gov (United States)

    Nobrega Passos, E.; de Freitas Assad, L.; Landau, L.

    2013-05-01

    The South Atlantic Ocean (SAO) is constituted by different density water masses. Among these, the South Atlantic Central Water (SACW) is formed on the Brazil-Falkland Confluence region (BFC) and once formed, it becomes part of the Subtropical Gyre. When approaching again the Brazilian coast, this water mass bifurcates next to São Tomé Cape and part of it flows to the North and part to the South. There is another bifurcation that formed the sub-gyre of the SAO and occurs near 30°S. This work aims to analyze the seasonal variability associated to the SACW trajectory on the SAO basin. To achieve this goal, ECCO2 project's time series of prognostic fields were analysed. The parameters evaluated were temperature, salinity and the zonal and meridional velocity components in averaged monthly fields between January 1992 and November 2010. First a climatological year was calculated and was composed by means from all time series for each month. And second, it was estimate seasonally means for the south hemisphere to summer, autumn, winter and springer. For the analysis, the SACW was separated from the rest of the water masses by isolating it for its temperature, salinity and density index. Then the volume transport (VT) was calculated for seven different sections: A (10°S and 36°W-30°W), B (35°S and 55°W-45°W), C (40°W and 37°S-43°S), D (34°S and 7°E-20°E), E (20°E and 34°S-45°S), F (20°W and 27°S-33°S) and G (10°W and 20°S-25°S). The VT integrated on the water column occupied by SACW was calculated from the zonal and meridional velocities. The analysis showed that the VT balance between the sections is consistent with the climatologic analysis, according to scientific references. The analysis of the climatological VT showed that the VT field integrated in SAWC levels is also consistent with scientific reference. On the seasonal analysis, the sections A and F show a stronger VT during autumn. Since section A is formed from part of the flux of section

  5. BOTANyCA

    OpenAIRE

    Armenta, Almudena; Guerrero, Teresa

    2012-01-01

    Esta publicación se realiza con motivo de la exposición titulada BOTANyCA celebrada en el Real Jardín Botánico de Madrid del 10 al 21 de octubre de 2012. Dicha exposición fue llevada a cabo por el Grupo de Investigación, Arte, Ciencia y Naturaleza de la Universidad Complutense de Madrid en colaboración con el Real Jardín Botánico. Comisariado de la exposición: Almudena Armenta y Teresa Guerrero. Coordinación técnica: Esther García Guillén y Marga Juárez Canga. Artistas participantes: Almudena...

  6. 精神病性症状的稳定期双相障碍I型患者认知功能MoCA评估及相关因素分析%Stable period of psychotic symptoms in bipolar disorder MoCA and related factors of cognitive function assessment in patients with type I analysis

    Institute of Scientific and Technical Information of China (English)

    李海涛

    2015-01-01

    The cognitive function of patients with I type related causes damage of bipolar disorder objective to investigate and analysis of psychotic symptoms in stable period. Methods In 2010 July to 2013 July in our hospital treated 30 cases of stable pa-tients with bipolar disorder type I of mental illness as the observation group,and 30 normal healthy people were selected as control group,using Montreal cognitive assessment scale for assessment of all MoCA into the study of the cognitive leve. Results the obser-vation group the patients cognitive function evaluation scores were significantly lower than those of normal control group,the differ-ence between the groups was significant (P<0.05);the 1 groups were observed and the observation group and the control group in the 2 digit symbol,digit span,testing and card connection classification scores were significant difference (P<0.05). Conclusion There is a correlation conclusion patients with depression and cognitive function score,manic score,and the correlation with course of disease and cognitive impairment as weaker.%目的:探讨与分析精神病性症状的稳定期双相障碍I型患者认知功能受损的相关原因。方法将2010年7月—2013年7月于该院接受治疗的30例稳定期双相障碍I型精神病患者作为观察组,同时选取30例正常健康人作为对照组,分析患者认知功能受损原因。结果①观察组患者各项认知功能评价成绩均明显差于正常对照组,组间对比差异有统计学意义(P<0.05);②观察1组、观察2组与对照组在数字符号、数字广度、连线测试与卡片分类评分方面均差异有统计学意义(P<0.05)。③观察组数字广度、连线测验-A、连线测验-B与病程均呈弱相关(r=-0.21、-0.19、0.20、0.22,P<0.05);而数字符号、数字广度、连线测验-A、连线测验-B与YMRS评分相关(r=-0.32、-0.21、-0.19、0.33、0.45,P<0.05);数字符号、数字广度、连线

  7. 75 FR 11133 - Fisheries of the South Atlantic; South Atlantic Fishery Management Council; Public Meeting

    Science.gov (United States)

    2010-03-10

    ... Wreckfish Shareholders for the South Atlantic region to discuss draft Amendment 20 to the Snapper Grouper... Shareholders for the South Atlantic region. See SUPPLEMENTARY INFORMATION. DATES: The meeting will take place... Wreckfish Shareholders on changes the Council is considering for the current ITQ program in Amendment 20...

  8. 78 FR 65974 - Atlantic Highly Migratory Species; Advisory Panel for Atlantic Highly Migratory Species Southeast...

    Science.gov (United States)

    2013-11-04

    ... not limited to data and models, used in stock assessments for oceanic sharks in the Atlantic Ocean... information, including but not limited to data and models, used in stock assessments for oceanic sharks in the... Atlantic oceanic sharks, it may be expanded to include other HMS, as needed. The primary purpose of...

  9. Response of the Atlantic overturning circulation to South Atlantic sources of buoyancy

    NARCIS (Netherlands)

    Weijer, W.; Ruijter, W.P.M. de; Sterl, A.; Drijfhout, S.

    2002-01-01

    The heat and salt input from the Indian to Atlantic Oceans by Agulhas Leakage is found to influence the Atlantic overturning circulation in a low-resolution Ocean General Circulation Model. The model used is the Hamburg Large-Scale Geostrophic (LSG) model, which is forced by mixed boundary condition

  10. 77 FR 35357 - Atlantic Highly Migratory Species; Commercial Atlantic Region Non-Sandbar Large Coastal Shark...

    Science.gov (United States)

    2012-06-13

    ...-Stevens Fishery Conservation and Management Act (16 U.S.C. 1801 et seq.). On January 24, 2012 (77 FR 3393... rule implementing the Atlantic HMS electronic dealer ] reporting system (76 FR 37750; June 28, 2011) or...; Commercial Atlantic Region Non-Sandbar Large Coastal Shark Fishery Opening Date AGENCY: National...

  11. 77 FR 61562 - Atlantic Highly Migratory Species; 2013 Atlantic Shark Commercial Fishing Season

    Science.gov (United States)

    2012-10-10

    ... accompanied the 2011 shark quota specifications rule (75 FR 76302; December 8, 2010). Thus, NMFS proposes to... Species; 2013 Atlantic Shark Commercial Fishing Season AGENCY: National Marine Fisheries Service (NMFS... season for the Atlantic commercial shark fisheries. Quotas would be adjusted as allowable based on...

  12. 76 FR 57709 - Atlantic Highly Migratory Species; Atlantic Shark Management Measures

    Science.gov (United States)

    2011-09-16

    .... As outlined in the September 20, 2010, ANPR (75 FR 57235), sharks have been federally managed since... Species; Atlantic Shark Management Measures AGENCY: National Marine Fisheries Service (NMFS), National... Atlantic shark landings; request for comments. SUMMARY: This notice announces the National Marine...

  13. Oxygen trends over five decades in the North Atlantic

    Science.gov (United States)

    Stendardo, I.; Gruber, N.

    2012-11-01

    We investigate long-term trends in dissolved oxygen in the North Atlantic from 1960 to 2009 on the basis of a newly assembled high-quality dataset consisting of oxygen data from three different sources: CARINA, GLODAP and the World Ocean Database. Oxygen trends are determined along isopycnal surfaces for eight regions and five water masses using a general least-squares linear regression method that accounts for temporal auto-correlation. Our results show a significant decrease of oxygen in the Upper (UW), Mode (MW) and Intermediate (IW) waters in almost all regions over the last 5 decades. Over the same period, oxygen increased in the Lower Intermediate Water (LIW) and Labrador Sea Water (LSW) throughout the North Atlantic. The observed oxygen decreases in the MW and IW of the northern and eastern regions are largely driven by changes in circulation and/or ventilation, while changes in solubility are the main driver for the oxygen decrease in the UW and the increases in the LIW and LSW. From 1960 until 2009 the UW, MW, and IW horizons have lost a total of -57 ± 34 Tmol, while the LIW and LSW horizons have gained 46 ± 47 Tmol, integrating to a roughly constant oxygen inventory in the North Atlantic. Comparing our oxygen trends with those of the oceanic heat content, we find an O2 to heat change ratio of -3.6 ± 2.8 nmol J-1 for the UW, MW and IW, and a ratio of -2.8 ± 3.4 nmol J-1 for the LIW and LSW. These ratios are substantially larger than those expected from solubility alone.

  14. Year aridity index patterns in northwest China and the relationship to summer North Atlantic sea surface temperature

    Institute of Scientific and Technical Information of China (English)

    YAN Yan; ZHAO Xinyi; ZHOU Liping

    2008-01-01

    Aim to linking the variability of drought in northwest China to the oceanic influence of North Atlantic SSTs at the background of global warming and at the regional climate change shifting stages, year aridity index variations in northwest China and summer North Atlantic sea surface temperature (SST) variations are examined for the 44 a period of 1961--2004 using singular value de-composition (SVD) analysis. Results show that the SST anomalies (SSTA) in the North Atlantic in summer reflected three basic models. The first SVD mode of SST pattern shows a dipole - like variation with the positive center located at southwest and nega-tive center at northeast of extratropical North Atlantic. And it strongly relates to the positive trend in AI variation in northwest China. The second coupled modes display the coherent positive anomalies in extratropical North Atlantic SST and the marked opposite trend of AI variability between north and south of Xinjiang. In addition, the lag correlation analysis of the first mode of SSTA and geopotential heights at 500 hPa variations also shows that the indication of the former influencing the latter configuration, which re-sult in higher air temperature and less precipitation when the SSTA in the North Atlantic Ocean in summer motivated Eurasian cir-culation of EA pattern, further to influence the wet - dry variations in northwest China by the ocean-to - atmosphere forcing.

  15. Inorganic and stable isotope geochemistry of tropical Atlantic/Caribbean planktonic foraminifera : implications for the reconstruction of upper ocean temperatures and stratification

    OpenAIRE

    Regenberg, Marcus

    2007-01-01

    Planktonic foraminifera from tropical Atlantic and Caribbean sediment-surface samples (0-1 cm) show general westward-directed increasing calcification depths depending on the east-west increase in thermocline depth. Positively related planktonic foraminiferal Mg/Ca and carbonate ion concentration in the Caribbean show well preserved Mg/Ca down to depths about 1.5 km above the lysocline, which equals a carbonate ion concentration of 26-18 µmol/kg. Species-specific calibrations of Mg/Ca with d1...

  16. Atlantic and Arctic sea-air CO2 fluxes, 1990–2009

    Directory of Open Access Journals (Sweden)

    C. Rödenbeck

    2012-08-01

    Full Text Available The Atlantic and Arctic oceans are critical components of the global carbon cycle. Here we quantify the net sea-air CO2 flux, for the first time, across different methodologies for consistent time and space scales, for the Atlantic and Arctic basins. We present the long-term mean, seasonal cycle, interannual variability and trends in sea-air CO2 flux for the period 1990 to 2009, and assign an uncertainty to each. We use regional cuts from global observations and modelling products, specifically a pCO2-based CO2 flux climatology, flux estimates from the inversion of oceanic and atmospheric data, and results from six ocean biogeochemical models. Additionally, we use basin-wide flux estimates from surface ocean pCO2 observations based on two distinct methodologies. Our best estimate of the contemporary sea-to-air flux of CO2 (sum of anthropogenic and natural components by the Atlantic between 40° S and 79° N is −0.49 ± 0.11 Pg C yr−1 and by the Arctic is −0.12 ± 0.06 Pg C yr−1, leading to a combined sea-to-air flux of −0.61 ± 0.12 Pg C yr−1 for the two decades (negative reflects ocean uptake. We do find broad agreement amongst methodologies with respect to the seasonal cycle in the subtropics of both hemispheres, but not elsewhere. Agreement with respect to detailed signals of interannual variability is poor; and correlations to the North Atlantic Oscillation are weaker in the North Atlantic and Arctic than in the equatorial region and South Subtropics. Linear trends for 1995 to 2009 indicate increased uptake and generally correspond between methodologies in the North Atlantic, but there is disagreement amongst methodologies in the equatorial region and South Subtropics.

  17. An assessment of the Atlantic and Arctic sea–air CO2 fluxes, 1990–2009

    Directory of Open Access Journals (Sweden)

    C. Rödenbeck

    2013-01-01

    Full Text Available The Atlantic and Arctic Oceans are critical components of the global carbon cycle. Here we quantify the net sea–air CO2 flux, for the first time, across different methodologies for consistent time and space scales for the Atlantic and Arctic basins. We present the long-term mean, seasonal cycle, interannual variability and trends in sea–air CO2 flux for the period 1990 to 2009, and assign an uncertainty to each. We use regional cuts from global observations and modeling products, specifically a pCO2-based CO2 flux climatology, flux estimates from the inversion of oceanic and atmospheric data, and results from six ocean biogeochemical models. Additionally, we use basin-wide flux estimates from surface ocean pCO2 observations based on two distinct methodologies. Our estimate of the contemporary sea–air flux of CO2 (sum of anthropogenic and natural components by the Atlantic between 40° S and 79° N is −0.49 ± 0.05 Pg C yr−1, and by the Arctic it is −0.12 ± 0.06 Pg C yr−1, leading to a combined sea–air flux of −0.61 ± 0.06 Pg C yr−1 for the two decades (negative reflects ocean uptake. We do find broad agreement amongst methodologies with respect to the seasonal cycle in the subtropics of both hemispheres, but not elsewhere. Agreement with respect to detailed signals of interannual variability is poor, and correlations to the North Atlantic Oscillation are weaker in the North Atlantic and Arctic than in the equatorial region and southern subtropics. Linear trends for 1995 to 2009 indicate increased uptake and generally correspond between methodologies in the North Atlantic, but there is disagreement amongst methodologies in the equatorial region and southern subtropics.

  18. Atlantic and Arctic sea-air CO2 fluxes, 1990-2009

    Science.gov (United States)

    Schuster, U.; McKinley, G. A.; Bates, N.; Chevallier, F.; Doney, S. C.; Fay, A. R.; González-Dávila, M.; Gruber, N.; Jones, S.; Krijnen, J.; Landschützer, P.; Lefèvre, N.; Manizza, M.; Mathis, J.; Metzl, N.; Olsen, A.; Rios, A. F.; Rödenbeck, C.; Santana-Casiano, J. M.; Takahashi, T.; Wanninkhof, R.; Watson, A. J.

    2012-08-01

    The Atlantic and Arctic oceans are critical components of the global carbon cycle. Here we quantify the net sea-air CO2 flux, for the first time, across different methodologies for consistent time and space scales, for the Atlantic and Arctic basins. We present the long-term mean, seasonal cycle, interannual variability and trends in sea-air CO2 flux for the period 1990 to 2009, and assign an uncertainty to each. We use regional cuts from global observations and modelling products, specifically a pCO2-based CO2 flux climatology, flux estimates from the inversion of oceanic and atmospheric data, and results from six ocean biogeochemical models. Additionally, we use basin-wide flux estimates from surface ocean pCO2 observations based on two distinct methodologies. Our best estimate of the contemporary sea-to-air flux of CO2 (sum of anthropogenic and natural components) by the Atlantic between 40° S and 79° N is -0.49 ± 0.11 Pg C yr-1 and by the Arctic is -0.12 ± 0.06 Pg C yr-1, leading to a combined sea-to-air flux of -0.61 ± 0.12 Pg C yr-1 for the two decades (negative reflects ocean uptake). We do find broad agreement amongst methodologies with respect to the seasonal cycle in the subtropics of both hemispheres, but not elsewhere. Agreement with respect to detailed signals of interannual variability is poor; and correlations to the North Atlantic Oscillation are weaker in the North Atlantic and Arctic than in the equatorial region and South Subtropics. Linear trends for 1995 to 2009 indicate increased uptake and generally correspond between methodologies in the North Atlantic, but there is disagreement amongst methodologies in the equatorial region and South Subtropics.

  19. An assessment of the Atlantic and Arctic sea-air CO2 fluxes, 1990-2009

    Science.gov (United States)

    Schuster, U.; McKinley, G. A.; Bates, N.; Chevallier, F.; Doney, S. C.; Fay, A. R.; González-Dávila, M.; Gruber, N.; Jones, S.; Krijnen, J.; Landschützer, P.; Lefèvre, N.; Manizza, M.; Mathis, J.; Metzl, N.; Olsen, A.; Rios, A. F.; Rödenbeck, C.; Santana-Casiano, J. M.; Takahashi, T.; Wanninkhof, R.; Watson, A. J.

    2013-01-01

    The Atlantic and Arctic Oceans are critical components of the global carbon cycle. Here we quantify the net sea-air CO2 flux, for the first time, across different methodologies for consistent time and space scales for the Atlantic and Arctic basins. We present the long-term mean, seasonal cycle, interannual variability and trends in sea-air CO2 flux for the period 1990 to 2009, and assign an uncertainty to each. We use regional cuts from global observations and modeling products, specifically a pCO2-based CO2 flux climatology, flux estimates from the inversion of oceanic and atmospheric data, and results from six ocean biogeochemical models. Additionally, we use basin-wide flux estimates from surface ocean pCO2 observations based on two distinct methodologies. Our estimate of the contemporary sea-air flux of CO2 (sum of anthropogenic and natural components) by the Atlantic between 40° S and 79° N is -0.49 ± 0.05 Pg C yr-1, and by the Arctic it is -0.12 ± 0.06 Pg C yr-1, leading to a combined sea-air flux of -0.61 ± 0.06 Pg C yr-1 for the two decades (negative reflects ocean uptake). We do find broad agreement amongst methodologies with respect to the seasonal cycle in the subtropics of both hemispheres, but not elsewhere. Agreement with respect to detailed signals of interannual variability is poor, and correlations to the North Atlantic Oscillation are weaker in the North Atlantic and Arctic than in the equatorial region and southern subtropics. Linear trends for 1995 to 2009 indicate increased uptake and generally correspond between methodologies in the North Atlantic, but there is disagreement amongst methodologies in the equatorial region and southern subtropics.

  20. Periodic fluctuations in deep water formation due to sea ice

    CERN Document Server

    Saha, Raj

    2015-01-01

    During the last ice age several quasi-periodic abrupt warming events took place. Known as Dansgaard-Oeschger (DO) events their effects were felt globally, although the North Atlantic experienced the largest temperature anomalies. Paleoclimate data shows that the fluctuations often occurred right after massive glacial meltwater releases in the North Atlantic and in bursts of three or four with progressively decreasing strengths. In this study a simple dynamical model of an overturning circulation and sea ice is developed with the goal of understanding the fundamental mechanisms that could have caused the DO events. Interaction between sea ice and the overturning circulation in the model produces self-sustained oscillations. Analysis and numerical experiments reveal that the insulating effect of sea ice causes the ocean to periodically vent out accumulated heat in the deep ocean into the atmosphere. Subjecting the model to idealized freshwater forcing mimicking Heinrich events causes modulation of the natural p...

  1. Accessing the nuclear symmetry energy in Ca+Ca collisions

    Directory of Open Access Journals (Sweden)

    Chbihi A.

    2012-07-01

    Full Text Available The status of the analysis of the INDRA-VAMOS experiement performed at GANIL, using the reactions 40,48Ca+40,48Ca reactions at 35AMeV, are presented. Isotopic distributions of fragments produced in multifragmentation events provide information on the importance of the surface term contribution in the symmetry energy by comparison to AMD predictions.

  2. Kinematics of the South Atlantic rift

    Directory of Open Access Journals (Sweden)

    C. Heine

    2013-01-01

    Full Text Available The South Atlantic rift basin evolved as branch of a large Jurassic-Cretaceous intraplate rift zone between the African and South American plates during the final breakup of western Gondwana. While the relative motions between South America and Africa for post-breakup times are well resolved, many issues pertaining to the fit reconstruction and particular the relation between kinematics and lithosphere dynamics during pre-breakup remain unclear in currently published plate models. We have compiled and assimilated data from these intraplated rifts and constructed a revised plate kinematic model for the pre-breakup evolution of the South Atlantic. Based on structural restoration of the conjugate South Atlantic margins and intracontinental rift basins in Africa and South America, we achieve a tight fit reconstruction which eliminates the need for previously inferred large intracontinental shear zones, in particular in Patagonian South America. By quantitatively accounting for crustal deformation in the Central and West African rift zone, we have been able to indirectly construct the kinematic history of the pre-breakup evolution of the conjugate West African-Brazilian margins. Our model suggests a causal link between changes in extension direction and velocity during continental extension and the generation of marginal structures such as the enigmatic Pre-salt sag basin and the São Paulo High. We model an initial E–W directed extension between South America and Africa (fixed in present-day position at very low extensional velocities until Upper Hauterivian times (≈126 Ma when rift activity along in the equatorial Atlantic domain started to increase significantly. During this initial ≈17 Myr-long stretching episode the Pre-salt basin width on the conjugate Brazilian and West African margins is generated. An intermediate stage between 126.57 Ma and Base Aptian is characterised by strain localisation, rapid lithospheric weakening in the

  3. Atlantic reef fish biogeography and evolution

    Science.gov (United States)

    Floeter, S.R.; Rocha, L.A.; Robertson, D.R.; Joyeux, J.C.; Smith-Vaniz, W.F.; Wirtz, P.; Edwards, A.J.; Barreiros, J.P.; Ferreira, C.E.L.; Gasparini, J.L.; Brito, A.; Falcon, J.M.; Bowen, B.W.; Bernardi, G.

    2008-01-01

    Aim: To understand why and when areas of endemism (provinces) of the tropical Atlantic Ocean were formed, how they relate to each other, and what processes have contributed to faunal enrichment. Location: Atlantic Ocean. Methods: The distributions of 2605 species of reef fishes were compiled for 25 areas of the Atlantic and southern Africa. Maximum-parsimony and distance analyses were employed to investigate biogeographical relationships among those areas. A collection of 26 phylogenies of various Atlantic reef fish taxa was used to assess patterns of origin and diversification relative to evolutionary scenarios based on spatio-temporal sequences of species splitting produced by geological and palaeoceanographic events. We present data on faunal (species and genera) richness, endemism patterns, diversity buildup (i.e. speciation processes), and evaluate the operation of the main biogeographical barriers and/or filters. Results: Phylogenetic (proportion of sister species) and distributional (number of shared species) patterns are generally concordant with recognized biogeographical provinces in the Atlantic. The highly uneven distribution of species in certain genera appears to be related to their origin, with highest species richness in areas with the greatest phylogenetic depth. Diversity buildup in Atlantic reef fishes involved (1) diversification within each province, (2) isolation as a result of biogeographical barriers, and (3) stochastic accretion by means of dispersal between provinces. The timing of divergence events is not concordant among taxonomic groups. The three soft (non-terrestrial) inter-regional barriers (mid-Atlantic, Amazon, and Benguela) clearly act as 'filters' by restricting dispersal but at the same time allowing occasional crossings that apparently lead to the establishment of new populations and species. Fluctuations in the effectiveness of the filters, combined with ecological differences among provinces, apparently provide a mechanism

  4. Dysmenorrhea: Painful Periods

    Science.gov (United States)

    ... Management Education & Events Advocacy For Patients About ACOG Dysmenorrhea: Painful Periods Home For Patients Search FAQs Dysmenorrhea: ... Dysmenorrhea: Painful Periods FAQ046, January 2015 PDF Format Dysmenorrhea: Painful Periods Gynecologic Problems What is dysmenorrhea? How ...

  5. An objective criterion for determining the South Atlantic Convergence Zone

    Directory of Open Access Journals (Sweden)

    Tercio eAmbrizzi

    2015-04-01

    Full Text Available The South Atlantic Convergence Zone (SACZ is the dominant summertime cloudiness feature of subtropical South America and the western South Atlantic Ocean, having a significant influence on the precipitation regime of southeastern Brazil. This paper proposes an objective criterion based mainly on precipitation, as this variable is easily obtained on general circulation models simulating past, present and future climate. Usually most SACZ studies use emerging long wave radiation as a precipitation proxy. This is enough to describe event position at first, but using precipitation would allow for better quantification, especially for climate studies, where precipitation is indispensable. An assessment was carried out to find out if classical DJF period is ideal for determining the SACZ for the present climate and future scenarios. In general the SACZ event detection criterion showed quite satisfactory results when event dates were previously known. When it was applied to future climate scenario it identified a number of events compatible with the present climate. The SACZ was well defined for both the simulated and observed precipitation data.

  6. An experimental study of the Atlantic variability on interdecadal timescales

    Directory of Open Access Journals (Sweden)

    M. Vincze

    2012-06-01

    Full Text Available A series of laboratory experiments has been carried out to model the basic dynamics of the multidecadal variability observed in North Atlantic sea surface temperature (SST records. According to the minimal numerical sector model introduced by te Raa and Dijkstra (2002, the three key components to excite such a low-frequency variability are rotation, meridional temperature gradient and additive thermal noise in the surface heat forcing. If these components are present, periodic perturbations of the overturning background flow are excited, leading to thermal Rossby mode like propagation of anomalous patches in the SST field. Our tabletop scale setup was built to capture this phenomenon, and to test whether the aforementioned three components are indeed sufficient to generate a low-frequency variability in the system. The results are compared to those of the numerical models, as well as to oceanic SST reanalysis records. To the best of our knowledge, the experiment described here is the very first to investigate the dynamics of the North Atlantic multidecadal variability in a laboratory-scale setup.

  7. Carbonate reservoir plays in the South Atlantic and worldwide analogs

    Science.gov (United States)

    Mohriak, Webster

    2015-04-01

    This work presents a summary of the geological, geophysical and petrophysical challenges for interpretation of post-salt and presalt carbonate rocks that constitute one of the main reservoirs in the hydrocarbon accumulations in the South Atlantic, particularly in the Campos and Santos basins offshore Brazil and in the Angola -Gabon conjugate margins. Carbonate rocks associated with salt tectonics constitute one of the main exploratory plays in several basins worldwide, and recently have yielded large petroleum discoveries in the southeastern Brazilian continental margin (Santos Basin) and also in Angola (Kwanza Basin) . The presalt microbialite reservoirs are sealed by evaporites and the origin of these rocks is still controversial. One current of interpretation assumes they are associated with reefs and carbonate buildups formed during periods of sea-level rises in a desiccating basin. Other currents of interpretation assume that these rocks might be associated with hydrothermal fluids and chemical precipitation of carbonates in a basin affected by volcanic episodes, resulting in travertine deposits with secondary biogenic growth. We present examples of post-salt oil fields involving Albian carbonates in the South Atlantic, and also discuss the presalt plays recently drilled in ultradeep waters. The presalt carbonate reservoirs are compared with possible microbialite analogs in the sedimentary basins of Brazil dating from Neoproterozoic to Recent, and their similarities and differences in terms of depositional setting and petrophysical parameters from the Late Aptian presalt carbonate rocks that have been sampled in the Santos and Kwanza basins.

  8. Nitrous oxide in the North Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    S. Walter

    2006-01-01

    Full Text Available In order to get a comprehensive picture of the distribution of nitrous oxide (N2O in the North Atlantic Ocean, measurements of dissolved nitrous oxide were made during three cruises in the tropical, subtropical and cold-temperate North Atlantic Ocean in October/November 2002, March/April 2004, and May 2002, respectively. To account for the history of atmospheric N2O, we suggest a new depth-dependent calculation of excess N2O (ΔN2O. N2O depth profiles showed supersaturation throughout the water column with a distinct increasing trend from the cold-temperate to the tropical region. Lowest nitrous oxide concentrations, near equilibrium and with an average of 11.0±1.7 nmol L−1, were found in the cold-temperate North Atlantic where the profiles showed no clear maxima. Highest values up to 37.3 nmol L−1 occurred in the tropical North Atlantic with clear maxima at approximately 400 m. A positive correlation of nitrous oxide with nitrate, as well as excess nitrous oxide with the apparent oxygen utilization (AOU, was only observed in the subtropical and tropical regions. Therefore, we conclude that the formation of nitrous oxide via nitrification occurs in the tropical region rather than in the cold-temperate region of the North Atlantic Ocean

  9. Ostracode Mg/Ca Paleothermometry: Applications and Complications

    Science.gov (United States)

    Cronin, T. M.; Dwyer, G. S.

    2007-12-01

    Ostracode (bivalved Crustacea) shell Mg/Ca paleothermometry has wide applicability in Cenozoic paleoclimatology over 101 to 107 year timescales because they are commonly fossilized, live in freshwater, shallow- and deep-marine habitats, and grow by molting, which minimizes Mg/Ca variability due to ontogenetic variability. Two empirically derived Mg/Ca-temperature calibrations based on core top and culturing include one for the shallow marine, estuarine genus Loxoconcha (5 to 30°C) and another for deep-sea genus Krithe (hockey stick temperature curve. The latter produced evidence for decreased deep-sea temperature during glacial intervals and the first Atlantic-wide reconstruction of deep-sea temperature during the warm mid-Pliocene. In addition to temperature, however, factors such as host-water magnesium concentrations, salinity, intra-shell, intra-population, and interspecific variabilility, seasonality, biological factors (shell secretion rate), and post-mortem dissolution can contribute to scatter in calibration datasets and uncertainty in paleotemperature estimates. We will review these processes, present a new 2000 year Chesapeake temperature record, and discuss its relation to twentieth century climate change.

  10. Oceanographic temperature, salinity, nitrate, phosphate, silicate, primary productivity, pigments, pCO2 and other measurements collected using bottle and CTD from multiple platforms in the North Atlantic during 1988 to 2006 (NODC Accession 0032053)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Chemical, biological, and physical profile data collected as part of the Bermuda-Atlantic Time Series Study (BATS) for the period 1988-December 2006 at Bermuda...

  11. Low-latitude control of interhemispheric sea-surface temperature contrast in the tropical Atlantic over the past 21 kyears: the possible role of SE trade winds

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.H.; Schneider, R.R. [Fachbereich Geowissenschaften, Universitaet Bremen, Klagenfurter Strasse, 28359 Bremen (Germany)

    2003-09-01

    To stimulate a discussion on the role of tropical atmospheric circulation versus thermohaline circulation changes for tropical Atlantic sea-surface temperature (SST) variations, we present a record of the SST contrast ({delta}SST) between the tropical northwest and southeast Atlantic from the Last Glacial Maximum to the Late Holocene. The {delta}SST was calculated from two alkenone-derived SST records; one from the Caribbean Sea and the other from the Angola Basin. Changes in the cross-equatorial {delta}SST were then compared with an abundance record of Florisphaera profunda from the equatorial Atlantic, which is indicative of SE trade-wind induced variations in thermocline depth in the equatorial divergence zone. This comparison implies that the Last Glacial Maximum, the Younger Dryas, and the Mid to Late Holocene were periods of strong SE trade winds, which led to an intense upwelling-related cooling in the southeast Atlantic and concurrently enhanced advection of warm tropical South Atlantic waters into the western tropical Atlantic. Accordingly, a coupled ocean-atmospheric process has probably created a dipole-like SST distribution pattern in the tropical Atlantic during these three distinct climatic periods. In contrast, Heinrich Event 1, the Boelling-Alleroed, and the Early Holocene were intervals of weakened SE trade winds, causing a warming in the southeast Atlantic. However, synchronous warming in both regions during Heinrich Event 1 can be partially attributed to a weakening of thermohaline overturning which caused a reduced northward heat transport from the low-latitude to the high-latitude North Atlantic. (orig.)

  12. Fine tuning of cytosolic Ca2+ oscillations [version 1; referees: 3 approved

    Directory of Open Access Journals (Sweden)

    Geneviève Dupont

    2016-08-01

    Full Text Available Ca2+ oscillations, a widespread mode of cell signaling, were reported in non-excitable cells for the first time more than 25 years ago. Their fundamental mechanism, based on the periodic Ca2+ exchange between the endoplasmic reticulum and the cytoplasm, has been well characterized. However, how the kinetics of cytosolic Ca2+ changes are related to the extent of a physiological response remains poorly understood. Here, we review data suggesting that the downstream targets of Ca2+ are controlled not only by the frequency of Ca2+ oscillations but also by the detailed characteristics of the oscillations, such as their duration, shape, or baseline level. Involvement of non-endoplasmic reticulum Ca2+ stores, mainly mitochondria and the extracellular medium, participates in this fine tuning of Ca2+ oscillations. The main characteristics of the Ca2+ exchange fluxes with these compartments are also reviewed.

  13. Mechanics of Old Faithful Geyser, Calistoga, CA

    Science.gov (United States)

    Rudolph, M.L.; Manga, M.; Hurwitz, Shaul; Johnston, Malcolm J.; Karlstrom, L.; Wang, Chun-Yong

    2012-01-01

    In order to probe the subsurface dynamics associated with geyser eruptions, we measured ground deformation at Old Faithful Geyser of Calistoga, CA. We present a physical model in which recharge during the period preceding an eruption is driven by pressure differences relative to the aquifer supplying the geyser. The model predicts that pressure and ground deformation are characterized by an exponential function of time, consistent with our observations. The geyser's conduit is connected to a reservoir at a depth of at least 42 m, and pressure changes in the reservoir can produce the observed ground deformations through either a poroelastic or elastic mechanical model.

  14. Evolutionary diversity among Atlantic coast mangroves

    Science.gov (United States)

    Dodd, Richard S.; Rafii, Zara A.; Fromard, François; Blasco, François

    1998-06-01

    Current knowledge of intraspecific variation of mangrove species is limited in terms of rangewide distributions and is mostly restricted to morphological analyses, which have indicated a high degree of homogeneity. However, our analyses of the aliphatic hydrocarbon and triterpenoid fraction of foliar waxes (by gas chromatography and mass spectroscopy) of mangrove species ( Rhizophora mangle, Avicennia germinans and Laguncularia racemosa) from Gabon in West Africa and French Guiana in South America show significant genetic differentiation between eastern and western Atlantic provenances. The greater diversity in lipid composition, and the tendency for longer carbon chain lengths in all taxa from Africa, may suggest that American mangroves exhibit derived characteristics. A consequence of this hypothesis would be that Atlantic mangroves are unlikely to have dispersed from the Tethys via the Pacific, as has been proposed by some authors. More widespread sampling within the Atlantic and east Pacific region is needed to support and confirm these results.

  15. 75 FR 16830 - Geological and Geophysical Exploration (G&G) on the Mid- and South Atlantic Outer Continental...

    Science.gov (United States)

    2010-04-02

    ... January 21, 2009, (74 FR 3636). The comment period on the earlier NOI closed on March 23, 2009. MMS did... (PEIS) for Future Industry G&G Activity on the Mid- and South Atlantic OCS. SUMMARY: Pursuant to the... Intercontinental Hotel, George Bush Intercontinental Airport, 18700 John F. Kennedy Boulevard, Houston, Texas...

  16. 75 FR 9864 - Fisheries of the Caribbean, Gulf of Mexico and South Atlantic; Comprehensive Ecosystem-Based...

    Science.gov (United States)

    2010-03-04

    ... of availability (NOA); request for comments. SUMMARY: The South Atlantic Fishery Management Council... comments, recommendations, and information received during the comment period on this NOA. A proposed rule... NOA, and consistency with the Magnuson-Stevens Act and other applicable laws, NMFS will publish...

  17. CARINA alkalinity data in the Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    A. Velo

    2009-08-01

    Full Text Available Data on carbon and carbon-relevant hydrographic and hydrochemical parameters from previously non-publicly available cruise data sets in the Arctic, Atlantic and Southern Ocean have been retrieved and merged to a new database: CARINA (CARbon IN the Atlantic.

    These data have gone through rigorous quality control (QC procedures to assure the highest possible quality and consistency. The data for most of the measured parameters in the CARINA data base were objectively examined in order to quantify systematic differences in the reported values, i.e. secondary quality control. Systematic biases found in the data have been corrected in the data products, i.e. three merged data files with measured, calculated and interpolated data for each of the three CARINA regions; Arctic, Atlantic and Southern Ocean. Out of a total of 188 cruise entries in the CARINA database, 98 were conducted in the Atlantic Ocean and of these, 75 cruises report alkalinity values.

    Here we present details of the secondary QC on alkalinity for the Atlantic Ocean part of CARINA. Procedures of quality control, including crossover analysis between cruises and inversion analysis of all crossover data are briefly described. Adjustments were applied to the alkalinity values for 16 of the cruises in the Atlantic Ocean region. With these adjustments the CARINA database is consistent both internally as well as with GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s. Based on our analysis we estimate the internal accuracy of the CARINA-ATL alkalinity data to be 3.3 μmol kg−1. The CARINA data are now suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation.

  18. CARINA: nutrient data in the Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    T. Tanhua

    2009-07-01

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

  19. Report of the Regional Coordination Meeting for the North Atlantic 2014 (RCM NA 2014)

    OpenAIRE

    Rodríguez-Gutiérrez, J. (José); Juárez, A.; ZENNER A.; Harley, B.; J./Elson; Beek, F.; ZARAUZ L.; Mugerza, E.; McCorminck, H.; Reis, D.; Ulleweit, J.; Pout, A. (Alastair); DINTHEER C.; Azevedo, M.; Dias, M.

    2014-01-01

    The 11th RCM North Atlantic was held in Horta (Portugal) 22-26 September 2014. Due to the delayed introduction of the revised DCF the European Commission decided a roll-over in 2013 meaning Member States National Programmes 2011-2013 remains unchanged for the period 2014-2017. The limitations this decision brings for coordination of current MS national programmes have allowed RCM NA to focus in three major different aspects of the data collection where...

  20. Low-frequency variability of the Tropical Atlantic surface topography : altimetry and model comparison

    OpenAIRE

    Arnault, Sabine; Morlière, Alain; Merle, Jacques

    1992-01-01

    Altimetric data, climatological hydrological data, and numerical model results are compared over the Tropical Atlantic ocean between november 1986 and november 1988. All reproduce the seasonal cycle of the dynamic topography rather well, and the agreement is particularly good between altimetry and the primitive equation model. The study of the 1986-1988 period reveals interannual events evidenced by both the altimetry and the models, especially during spring 1988 in the Gulf of Guinea. (Résum...

  1. Temporal dynamics of Prochlorococcus ecotypes in the Atlantic and Pacific oceans

    OpenAIRE

    Malmstrom, Rex R.; Coe, Allison; Kettler, Gregory Carl; Martiny, Adam C.; Frias-Lopez, Jorge; Zinser, Erik R.; Chisholm, Sallie

    2010-01-01

    To better understand the temporal and spatial dynamics of Prochlorococcus populations, and how these populations co-vary with the physical environment, we followed monthly changes in the abundance of five ecotypes—two high-light adapted and three low-light adapted—over a 5-year period in coordination with the Bermuda Atlantic Time Series (BATS) and Hawaii Ocean Time-series (HOT) programs. Ecotype abundance displayed weak seasonal fluctuations at HOT and strong seasonal fluctuations at BATS. F...

  2. Projection of North Atlantic Oscillation and its effect on tracer transport

    OpenAIRE

    Bacer, Sara; Christoudias, Theodoros; Pozzer, Andrea

    2016-01-01

    The North Atlantic Oscillation (NAO) plays an important role in the climate variability of the Northern Hemisphere with significant consequences on long-range pollutant transport. We investigate the evolution of pollutant transport in the 21st century influenced by the NAO under a global climate change scenario. We use a free-running simulation performed by the ECHAM/MESSy Atmospheric Chemistry (EMAC) model coupled with the ocean general circulation model MPIOM, covering the period from 1950 ...

  3. Hydrology of surface waters and thermohaline circulation during the last glacial period; Hydrologie des eaux de surface et circulation thermohaline au cours de la derniere periode glaciaire

    Energy Technology Data Exchange (ETDEWEB)

    Vidal, L.

    1996-03-27

    Sedimentological studies on oceanic cores from the north Atlantic have revealed, over the last glacial period, abrupt climatic changes with a periodicity of several thousand years which contrasts strongly with the glacial-interglacial periodicity (several tens of thousand years). These periods of abrupt climate changes correspond to massive icebergs discharges into the north Atlantic. The aim of this work was to study the evolution of the thermohaline circulation in relation to these episodic iceberg discharges which punctuated the last 60 ka. To reconstruct the oceanic circulation in the past, we have analysed oxygen and carbon stable isotopes on benthic foraminifera from north Atlantic deep-sea cores. First of all, the higher temporal resolution of sedimentary records has enabled us to establish a precise chrono-stratigraphy for the different cores. Then, we have shown the close linkage between surface water hydrology and deep circulation, giving evidence of the sensibility of thermohaline circulation to melt water input in the north Atlantic ocean. Indeed, changes in deep circulation are synchronous from those identified in surface waters and are recorded on a period which lasted {approx} 1500 years. Deep circulation reconstructions, before and during a typical iceberg discharge reveal several modes of circulation linked to different convection sites at the high latitudes of the Atlantic basin. Moreover, the study of the last glacial period gives the opportunity to differentiate circulation changes due to the external forcing (variations of the orbital parameters) and those linked to a more local forcing (icebergs discharges). 105 refs., 50 figs., 14 tabs., 4 appends.

  4. Regionally coherent Little Ice Age cooling in the Atlantic Warm Pool

    Science.gov (United States)

    Richey, J.N.; Poore, R.Z.; Flower, B.P.; Quinn, T.M.; Hollander, D.J.

    2009-01-01

    We present 2 new decadal-resolution foraminiferal Mg/Ca-SST records covering the past 6-8 centuries from the northern Gulf of Mexico (GOM). These records provide evidence for a Little Ice Age (LIA) cooling of 2??C, consistent with a published Mg/Ca record from Pigmy Basin. Comparison of these 3 records with existing SST proxy records from the GOM-Caribbean region show that the magnitude of LIA cooling in the Atlantic Warm Pool (AWP) was significantly larger than the mean hemispheric cooling of <1??C. We propose that a reduction in the intensity and spatial extent of the AWP during the LIA, combined with associated changes in atmospheric circulation may account for the regional SST patterns observed in the GOM-Caribbean region during the LIA. Copyright 2009 by the American Geophysical Union.

  5. Linkages between atmospheric blocking, sea ice export through Fram Strait and the Atlantic Meridional Overturning Circulation.

    Science.gov (United States)

    Ionita, M; Scholz, P; Lohmann, G; Dima, M; Prange, M

    2016-01-01

    As a key persistent component of the atmospheric dynamics, the North Atlantic blocking activity has been linked to extreme climatic phenomena in the European sector. It has also been linked to Atlantic multidecadal ocean variability, but its potential links to rapid oceanic changes have not been investigated. Using a global ocean-sea ice model forced with atmospheric reanalysis data, here it is shown that the 1962-1966 period of enhanced blocking activity over Greenland resulted in anomalous sea ice accumulation in the Arctic and ended with a sea ice flush from the Arctic into the North Atlantic Ocean through Fram Strait. This event induced a significant decrease of Labrador Sea water surface salinity and an abrupt weakening of the Atlantic Meridional Overturning Circulation (AMOC) during the 1970s. These results have implications for the prediction of rapid AMOC changes and indicate that an important part of the atmosphere-ocean dynamics at mid- and high latitudes requires a proper representation of the Fram Strait sea ice transport and of the synoptic scale variability such as atmospheric blocking, which is a challenge for current coupled climate models. PMID:27619955

  6. The intertropical convergence zone modulates intense hurricane strikes on the western North Atlantic margin.

    Science.gov (United States)

    van Hengstum, Peter J; Donnelly, Jeffrey P; Fall, Patricia L; Toomey, Michael R; Albury, Nancy A; Kakuk, Brian

    2016-01-01

    Most Atlantic hurricanes form in the Main Development Region between 9°N to 20°N along the northern edge of the Intertropical Convergence Zone (ITCZ). Previous research has suggested that meridional shifts in the ITCZ position on geologic timescales can modulate hurricane activity, but continuous and long-term storm records are needed from multiple sites to assess this hypothesis. Here we present a 3000 year record of intense hurricane strikes in the northern Bahamas (Abaco Island) based on overwash deposits in a coastal sinkhole, which indicates that the ITCZ has likely helped modulate intense hurricane strikes on the western North Atlantic margin on millennial to centennial-scales. The new reconstruction closely matches a previous reconstruction from Puerto Rico, and documents a period of elevated intense hurricane activity on the western North Atlantic margin from 2500 to 1000 years ago when paleo precipitation proxies suggest that the ITCZ occupied a more northern position. Considering that anthropogenic warming is predicted to be focused in the northern hemisphere in the coming century, these results provide a prehistoric analog that an attendant northern ITCZ shift in the future may again return the western North Atlantic margin to an active hurricane interval. PMID:26906670

  7. Low-frequency storminess signal at Bermuda linked to cooling events in the North Atlantic region

    Science.gov (United States)

    Hengstum, Peter J.; Donnelly, Jeffrey P.; Kingston, Andrew W.; Williams, Bruce E.; Scott, David B.; Reinhardt, Eduard G.; Little, Shawna N.; Patterson, William P.

    2015-02-01

    North Atlantic climate archives provide evidence for increased storm activity during the Little Ice Age (150 to 600 calibrated years (cal years) B.P.) and centered at 1700 and 3000 cal years B.P., typically in centennial-scale sedimentary records. Meteorological (tropical versus extratropical storms) and climate forcings of this signal remain poorly understood, although variability in the North Atlantic Oscillation (NAO) or Atlantic Meridional Overturning Circulation (AMOC) are frequently hypothesized to be involved. Here we present records of late Holocene storminess and coastal temperature change from a Bermudian submarine cave that is hydrographically circulated with the coastal ocean. Thermal variability in the cave is documented by stable oxygen isotope values of cave benthic foraminifera, which document a close linkage between regional temperature change and NAO phasing during the late Holocene. However, erosion of terrestrial sediment into the submarine cave provides a "storminess signal" that correlates with higher-latitude storminess archives and broader North Atlantic cooling events. Understanding the driver of this storminess signal will require higher-resolution storm records to disentangle the contribution of tropical versus extratropical cyclones and a better understanding of cyclone activity during hemispheric cooling periods. Most importantly, however, the signal in Bermuda appears more closely correlated with proxy-based evidence for subtle AMOC reductions than NAO phasing.

  8. Linkages between atmospheric blocking, sea ice export through Fram Strait and the Atlantic Meridional Overturning Circulation

    Science.gov (United States)

    Ionita, M.; Scholz, P.; Lohmann, G.; Dima, M.; Prange, M.

    2016-09-01

    As a key persistent component of the atmospheric dynamics, the North Atlantic blocking activity has been linked to extreme climatic phenomena in the European sector. It has also been linked to Atlantic multidecadal ocean variability, but its potential links to rapid oceanic changes have not been investigated. Using a global ocean-sea ice model forced with atmospheric reanalysis data, here it is shown that the 1962-1966 period of enhanced blocking activity over Greenland resulted in anomalous sea ice accumulation in the Arctic and ended with a sea ice flush from the Arctic into the North Atlantic Ocean through Fram Strait. This event induced a significant decrease of Labrador Sea water surface salinity and an abrupt weakening of the Atlantic Meridional Overturning Circulation (AMOC) during the 1970s. These results have implications for the prediction of rapid AMOC changes and indicate that an important part of the atmosphere-ocean dynamics at mid- and high latitudes requires a proper representation of the Fram Strait sea ice transport and of the synoptic scale variability such as atmospheric blocking, which is a challenge for current coupled climate models.

  9. Correcting North Atlantic sea surface salinity biases in the Kiel Climate Model: influences on ocean circulation and Atlantic Multidecadal Variability

    Science.gov (United States)

    Park, T.; Park, W.; Latif, M.

    2016-10-01

    A long-standing problem in climate models is the large sea surface salinity (SSS) biases in the North Atlantic. In this study, we describe the influences of correcting these SSS biases on the circulation of the North Atlantic as well as on North Atlantic sector mean climate and decadal to multidecadal variability. We performed integrations of the Kiel Climate Model (KCM) with and without applying a freshwater flux correction over the North Atlantic. The quality of simulating the mean circulation of the North Atlantic Ocean, North Atlantic sector mean climate and decadal variability is greatly enhanced in the freshwater flux-corrected integration which, by definition, depicts relatively small North Atlantic SSS biases. In particular, a large reduction in the North Atlantic cold sea surface temperature bias is observed and a more realistic Atlantic Multidecadal Variability simulated. Improvements relative to the non-flux corrected integration also comprise a more realistic representation of deep convection sites, sea ice, gyre circulation and Atlantic Meridional Overturning Circulation. The results suggest that simulations of North Atlantic sector mean climate and decadal variability could strongly benefit from alleviating sea surface salinity biases in the North Atlantic, which may enhance the skill of decadal predictions in that region.

  10. 75 FR 27219 - Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab Fisheries; 2010 Atlantic...

    Science.gov (United States)

    2010-05-14

    ... United States; Atlantic Deep-Sea Red Crab Fisheries; 2010 Atlantic Deep-Sea Red Crab Specifications...), Commerce. ACTION: Final rule. SUMMARY: NMFS issues final specifications for the 2010 Atlantic deep- sea red... document is also accessible via the Internet at http://www.nefmc.org . NMFS prepared a Final...

  11. Temporal and spatial genetic differentiation in the crab Liocarcinus depurator across the Atlantic-Mediterranean transition.

    Science.gov (United States)

    Pascual, Marta; Palero, Ferran; García-Merchán, Víctor Hugo; Macpherson, Enrique; Robainas-Barcia, Aymée; Mestres, Francesc; Roda, Tania; Abelló, Pere

    2016-01-01

    Spatial genetic studies often require sampling broadly separated areas, difficult to access simultaneously. Although comparing localities surveyed at different time periods might result in spurious genetic differentiation, there is a general believe on the stability of genetic structure through time, particularly if sampled localities are isolated or very distant. By analysing spatial and temporal genetic differentiation of the portunid crab Liocarcinus depurator we assessed the contribution of historical and contemporary processes on population connectivity patterns across three main oceanographic discontinuities along the Atlantic-Mediterranean transition: Gibraltar Strait, Almeria-Oran Front and Ibiza Channel. A partial fragment of the cytochrome oxidase I gene was sequenced in 366 individuals collected from localities at both sides of each discontinuity during three time periods. Although localities showed genetic fluctuations through time, a significant gradient was detected along the coast for all sampling periods. Significant inter-annual differences identified within the Alicante area, north of the Almeria-Oran Front, were associated with shifts in the relative contribution of Atlantic and Mediterranean water masses. The persistence of a clinal pattern in the Atlantic-Mediterranean transition area together with local fluctuations suggests a complex balance of dispersal and selection. PMID:27431989

  12. Coral-based climate records from tropical South Atlantic

    DEFF Research Database (Denmark)

    Pereira, Natan S.; Sial, Alcides N.; Kikuchi, Ruy K.P.;

    2015-01-01

    Coral skeletons contain records of past environmental conditions due to their long life span and well calibrated geochemical signatures. C and O isotope records of corals are especially interesting, because they can highlight multidecadal variability of local climate conditions beyond...... the instrumental record, with high fidelity and sub-annual resolution. Although, in order to get an optimal geochemical signal in coral skeleton, sampling strategies must be followed. Here we report one of the first coral-based isotopic record from the Equatorial South Atlantic from two colonies of Porites...... the two colonies are observed, yet both record the 2009/2010 El Niño event - a period of widespread coral bleaching - as anomalously negative δ18O values (up to −1 permil). δ13C is found to be measurably affected by the El Niño event in one colony, by more positive values (+0.39 ‰), and together...

  13. Great Basin hydrology, paleoclimate, and connections with the North Atlantic: A speleothem stable isotope and trace element record from Lehman Caves, NV

    Science.gov (United States)

    Cross, Mellissa; McGee, David; Broecker, Wallace S.; Quade, Jay; Shakun, Jeremy D.; Cheng, Hai; Lu, Yanbin; Edwards, R. Lawrence

    2015-11-01

    uncertainties with the abrupt strengthening of the East Asian summer monsoon, which marks the end of both the Weak Monsoon Interval and Heinrich Stadial 11. Our records demonstrate a link between North Atlantic climate and Great Basin moisture during this time that is consistent with the interpretation of data from the last glacial period and may result from abrupt shifts in Atlantic Meridional Overturning Circulation affecting the strength of the Aleutian Low.

  14. Atlantic Meridional Overturning Circulation response to idealized external forcing

    Energy Technology Data Exchange (ETDEWEB)

    Park, W.; Latif, M. [Leibniz-Institut fuer Meereswissenschaften an der Universitaet Kiel, Kiel (Germany)

    2012-10-15

    The response of the Atlantic Meridional Overturning Circulation (AMOC) to idealized external (solar) forcing is studied in terms of the internal (unforced) AMOC modes with the Kiel Climate Model (KCM), a coupled atmosphere-ocean-sea ice general circulation model. The statistical investigation of KCM's internal AMOC variability obtained from a multi-millennial control run yields three distinct modes: a multi-decadal mode with a period of about 60 years, a quasi-centennial mode with a period of about 100 years and a multi-centennial mode with a period of about 300-400 years. Most variance is explained by the multi-centennial mode, and the least by the quasi-centennial mode. The solar constant varies sinusoidally with two different periods (100 and 60 years) in forced runs with KCM. The AMOC response to the external forcing is rather complex and nonlinear. It involves strong changes in the frequency structure of the variability. While the control run depicts multi-timescale behavior, the AMOC variability in the experiment with 100 year forcing period is channeled into a relatively narrow band centered near the forcing period. It is the quasi-centennial AMOC mode with a period of just under 100 years which is excited, although it is heavily damped in the control run. Thus, the quasi-centennial mode retains its period which does not correspond exactly to the forcing period. Surprisingly, the quasi-centennial mode is also most strongly excited when the forcing period is set to 60 years, the period of the multi-decadal mode which is rather prominent in the control run. It is largely the spatial structure of the forcing rather than its period that determines which of the three internal AMOC modes is excited. The results suggest that we need to understand the full modal structure of the internal AMOC variability in order to understand the circulation's response to external forcing. This could be a challenge for climate models: we cannot necessarily expect that the

  15. 76 FR 23935 - Atlantic Highly Migratory Species; Atlantic Shark Management Measures

    Science.gov (United States)

    2011-04-29

    ... or hammerhead sharks in the Coastal Fisheries Logbook. Currently, there is no commercial oceanic... Species; Atlantic Shark Management Measures AGENCY: National Marine Fisheries Service (NMFS), National... published in the Federal Register (71 FR 58058) final regulations, effective November 1, 2006...

  16. 78 FR 4129 - Fisheries of the South Atlantic; South Atlantic Fishery Management Council; Public Meetings

    Science.gov (United States)

    2013-01-18

    ... System (VMS), as well as a review of the VMS fact sheet. 2. Receive a presentation on the mobile phone... VMS requirements for vessels with South Atlantic commercial snapper grouper permits. This action...

  17. 78 FR 11809 - Fisheries of the Northeastern United States; Atlantic Bluefish Fishery; 2013-2014 Atlantic...

    Science.gov (United States)

    2013-02-20

    .... Christopher M. Moore, Executive Director, Mid-Atlantic Fishery Management Council, Suite 201, 800 N. State... overfishing. Authority: 16 U.S.C. 1801 et seq. Dated: February 12, 2013. Alan D. Risenhoover, Director,...

  18. 77 FR 8776 - Fisheries of the Northeastern United States; Atlantic Bluefish Fishery; 2012 Atlantic Bluefish...

    Science.gov (United States)

    2012-02-15

    .... Moore, Executive Director, Mid-Atlantic Fishery Management Council, Suite 201, 800 N. State Street... Monitoring Committee. Authority: 16 U.S.C. 1801 et seq. Dated: February 9, 2012. Alan D. Risenhoover,...

  19. Sulcando os mares: um historiador do império português enfrenta a "Atlantic History" Crossing the seas: a historian of the Portuguese Empire comes face to face with the "Atlantic History"

    Directory of Open Access Journals (Sweden)

    A.J.R. Russell-Wood

    2009-01-01

    Full Text Available Esta contribuição para a história tem duas dimensões. A que predomina é a historiográfica: a gênese e evolução da "Atlantic history", as suas características, ênfases e metodologia, e como diverge da história consciente de um quadro imperial. A segunda é um praticum: quer dizer, a minha tentativa em conceitualizar e organizar um artigo sobre "o Atlântico luso-afro-brasileiro" no período de cerca 1660 até cerca de 1760, segundo o que entendo ser as normas e preceitos do "Atlantic history". Fruto de tal experiência, concluo com avaliação em respeito dos prós e contras, do "Atlantic history", em comparação com outras historiografias e faço observações a respeito do seu potencial para abrir novos ramos de pesquisa para a História do Brasil Colonial.This contribution to history has two dimensions of which one predominates, being the historiography: the genesis and evolution of the "Atlantic History", its characteristics, emphases and methodology, and how it diverges from the conscious history of an imperial framework. The second is a practicum: that is to say, my attempt in conceptualizing and organizing an article about the "Luso-Afro-Brazilian Atlantic" in the period around 1660 up to around 1760" according to what is understood as the guidelines and precepts of the "Atlantic History". From the fruit of such experiences, I conclude with an evaluation of the pros and cons of the "Atlantic History", in comparison with other historiographies, and make observations with respect to its potential to open up new lines of research into Brazilian colonial history.

  20. Glacial climate sensitivity to different states of the Atlantic Meridional Overturning Circulation: results from the IPSL model

    Directory of Open Access Journals (Sweden)

    M. Kageyama

    2009-09-01

    Full Text Available Paleorecords from distant locations on the globe show rapid and large amplitude climate variations during the last glacial period. Here we study the global climatic response to different states of the Atlantic Meridional Overturning Circulation (AMOC as a potential explanation for these climate variations and their possible connections. We analyse three glacial simulations obtained with an atmosphere-ocean coupled general circulation model and characterised by different AMOC strengths (18, 15 and 2 Sv resulting from successive ~0.1 Sv freshwater perturbations in the North Atlantic. These AMOC states suggest the existence of a freshwater threshold for which the AMOC collapses. A weak (18 to 15 Sv AMOC decrease results in a North Atlantic and European cooling. This cooling is not homogeneous, with even a slight warming over the Norwegian Sea. Convection in this area is active in both experiments, but surprisingly stronger in the 15 Sv simulation, which appears to be related to interactions with the atmospheric circulation and sea-ice cover. Far from the North Atlantic, the climatic response is not significant. The climate differences for an AMOC collapse (15 to 2 Sv are much larger and of global extent. The timing of the climate response to this AMOC collapse suggests teleconnection mechanisms. Our analyses focus on the North Atlantic and surrounding regions, the tropical Atlantic and the Indian monsoon region. The North Atlantic cooling associated with the AMOC collapse induces a cyclonic atmospheric circulation anomaly centred over this region, which modulates the eastward advection of cold air over the Eurasian continent. This can explain why the cooling is not as strong over western Europe as over the North Atlantic. In the Tropics, the southward shift of the Inter-Tropical Convergence Zone appears to be strongest over the Atlantic and Eastern Pacific and results from an adjustment of the atmospheric and oceanic heat transports. Finally, the

  1. Response of the South Atlantic circulation to an abrupt collapse of the Atlantic meridional overturning circulation

    Energy Technology Data Exchange (ETDEWEB)

    Laurian, Audine [University of Hawai' i at Manoa, International Pacific Research Center, School of Ocean and Earth Science and Technology, Honolulu, HI (United States); Drijfhout, Sybren S. [Royal Netherlands Meteorological Institute, De Bilt (Netherlands)

    2011-08-15

    The South Atlantic response to a collapse of the North Atlantic meridional overturning circulation (AMOC) is investigated in the ECHAM5/MPI-OM climate model. A reduced Agulhas leakage (about 3.1 Sv; 1 Sv = 10{sup 6} m{sup 3} s{sup -1}) is found to be associated with a weaker Southern Hemisphere (SH) supergyre and Indonesian throughflow. These changes are due to reduced wind stress curl over the SH supergyre, associated with a weaker Hadley circulation and a weaker SH subtropical jet. The northward cross-equatorial transport of thermocline and intermediate waters is much more strongly reduced than Agulhas leakage in relation with an AMOC collapse. A cross-equatorial gyre develops due to an anomalous wind stress curl over the tropics that results from the anomalous sea surface temperature gradient associated with reduced ocean heat transport. This cross-equatorial gyre completely blocks the transport of thermocline waters from the South to the North Atlantic. The waters originating from Agulhas leakage flow somewhat deeper and most of it recirculates in the South Atlantic subtropical gyre, leading to a gyre intensification. This intensification is consistent with the anomalous surface cooling over the South Atlantic. Most changes in South Atlantic circulation due to global warming, featuring a reduced AMOC, are qualitatively similar to the response to an AMOC collapse, but smaller in amplitude. However, the increased northward cross-equatorial transport of intermediate water relative to thermocline water is a strong fingerprint of an AMOC collapse. (orig.)

  2. Population structure of Atlantic Mackerel (Scomber scombrus)

    DEFF Research Database (Denmark)

    Jansen, Teunis; Gislason, Henrik

    2013-01-01

    model where the population structure of mackerel is described as a dynamic cline, rather than as connected contingents. Temporal changes in hydrography and mackerel behavior may affect the steepness of the cline at various locations. The new interpretation of the population structure of Atlantic...

  3. Indian - Atlantic interocean exchange: variability and controls

    NARCIS (Netherlands)

    Schouten, Mathijs Wilhelmus

    2003-01-01

    South of Africa, warm Indian Ocean water enters the Atlantic Ocean by means of large Agulhas Rings. These rings, with diameters up to 350 km and reaching all the way to the ocean floor at 5 km depth, form an important link in the global thermohaline circulation, which is the driving force behind the

  4. Coccolithophores in the equatorial Atlantic Ocean

    DEFF Research Database (Denmark)

    Kinkel, Hanno; Baumann, K.-H.; Cepek, M.

    2000-01-01

    The present study was initiated to ascertain the significance of coccolithophores as a proxy for paleoceanographic and paleoproductivity studies in the equatorial Atlantic. Data from a range of different samples, from the plankton, surface sediments as well as sediment cores are shown and compare...

  5. Sonoma County, CA, 2013 Lidar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sonoma County Vegetation Mapping and LiDAR Consortium retained WSI to provide lidar and Orthophoto data and derived products in Sonoma County, CA. A classified LAS...

  6. CaPTC Biennial Meetings

    Science.gov (United States)

    CaPTC hosts the 'Biennial Science of Global Prostate Cancer Disparities in Black Men' conference to address the growing global public health problem of prostate cancer among Black men in industrialized and developing countries.

  7. CaWave user's guide

    International Nuclear Information System (INIS)

    CaWave User's Guide explains how to use the CaWave functions which were specifically written in PV-WAVE command language and C language for EPICS users. CaWave consists of a special set of external channel access functions which provides the PV-WAVE users with easy and flexible access of channel information across the IOC networks. It also provides a complete set of process variable event monitoring functions. This document also gives examples how a PV-WAVE user can interface to channel access devices. It is assumed that the user is already familiar with using PV-WAVE. Few simple example modules of using PV-WAVE command language with CaWave functions are also given in this document

  8. ENSO components of the Atlantic multidecadal oscillation and their relation to North Atlantic interannual coastal sea level anomalies

    Directory of Open Access Journals (Sweden)

    J. Park

    2012-11-01

    Full Text Available The El Niño Southern Oscillation (ENSO and the Atlantic Multidecadal Oscillation (AMO are known to influence coastal water levels along the east coast of the United States. By identifying empirical orthogonal functions (EOFs which coherently contribute from the Multivariate ENSO Index (MEI to the AMO index (AMOI, we characterize both the expression of ENSO in the unsmoothed AMOI, and coherent relationships between these indices and interannual sea level anomalies at six stations in the Gulf of Mexico and Western North Atlantic. Within the ENSO band (2–7 yr periods the total contribution of MEI to unsmoothed AMOI variability is 79%. Cross correlation suggests that the MEI leads expression of the ENSO signature in the AMOI by six months, consistent with the mechanism of an atmospheric bridge. Within the ENSO band, essentially all of the coupling between the unsmoothed AMOI and sea level anomalies is the result of ENSO expression in the AMOI. At longer periods we find decadal components of sea level anomalies linked to the AMOI at three southern stations (Key West, Pensacola, Charleston, but not at the northern stations (Baltimore, Boston, Portland, with values of coherence ranging from 20 to 50%. The coherence of MEI to coastal sea level anomalies has a different structure and is generally weaker than that of the ENSO expressed AMOI influence, suggesting distinct physical mechanisms are influencing sea level anomalies due to a direct ENSO teleconnection when compared to teleconnections based on ENSO expression in the AMOI. It is expected that applying this analysis to extremes of sea level anomalies will reveal additional influences.

  9. CA 242, a new tumour marker for pancreatic cancer: a comparison with CA 19-9, CA 50 and CEA.

    OpenAIRE

    Haglund, C.; Lundin, J; Kuusela, P.; Roberts, P. J.

    1994-01-01

    The serum expression of a novel tumour marker, CA 242, defined by monoclonal antibody C 242, was studied in 179 patients with pancreatic cancer. The results were compared with CA 19-9, CA 50 and CEA. CA 242 is a carbohydrate closely related, but not identical, to CA 19-9 and CA 50. The overall sensitivity of the CA 242 assay was 74%: 55% in stage I, 83% in stage II-III and 78% in stage IV disease. The specificity calculated from 112 patients with benign diseases was 91%. CA 19-9 had a higher ...

  10. Atlantic and indian oceans pollution in africa

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

  12. Effects of Aconitine on [Ca2+] Oscillation in Cultured Myocytes of Neonatal Rats

    Institute of Scientific and Technical Information of China (English)

    Yah LIU; Shiwei ZHANG; Man LIANG; Qian LIU; Liang LIU

    2008-01-01

    Summary: In order to investigate the effects of aconitine on [Ca2+] oscillation patterns in cultured myocytes of neonatal rats, fluorescent Ca2+ indicator Fluo-4 NW and laser scanning confocal microscope (LSCM) were used to detect the real-time changes of [Ca2+] oscillation patterns in the cultured myocytes before and after aconitine (1.0 μmol/L) incubation or antiarrhythmic peptide (AAP) and aconitine co-incubation. The results showed under control conditions, [Ca2+] oscillations were irregular but relatively stable, occasionally accompanied by small calcium sparks. After incubation of the cultures with aconitine, high frequency [Ca2+] oscillations emerged in both nuclear and cytoplasmic regions, whereas typical calcium sparks disappeared and the average [Ca2+] in the cytoplasm of the cardiomyocyte did not change significantly. In AAP-treated cultures, intraecllular [Ca2+] oscillation also changed, with periodic frequency, increased amplitudes and prolonged duration of calcium sparks. These patterns were not altered significantly by subsequent aconitine incubation. The basal value of [Ca2+] in nuclear region was higher than that in the cytoplasmic region, in the presence or absence of drugs, the [Ca2+] oscillated synchronously in both the nuclear and cytoplasmic regions of the same cardiomyocyte. It was concluded that although oscillating strenuously at high frequency, the average [Ca2+] in the cytoplasm of cardiomyocyte did not change significantly after aconitine incubation, compared to the controls. The observations indicate that aconitine induces the changes in [Ca2+] oscillation frequency other than the Ca2+ overload.

  13. North Atlantic and orbital controls on North American Monsoon rainfall for the past 25,000 years

    Science.gov (United States)

    Lachniet, M. S.; Bernal-Uruchurtu, J. P.; Asmerom, Y.; Polyak, V.; Vazquez-Selem, L.

    2011-12-01

    The paleoclimate controls on Mexican rainfall remain poorly understood, making it difficult to test hypotheses of late Quaternary climate changes in the North American Monsoon region. A high-resolution and chronologically robust integrative paleoclimate history for central and southwestern Mexico is required to evaluate the climate context associated with the late glacial peopling of Mesoamerica, the Holocene domestication of maize, and climate's influence on several advanced pre-Colombian civilizations. Herein, we combine new and previously published precipitation- and temperature-sensitive proxy records to delineate the paleoclimatic history of the "Mesoamerican Monsoon" region since ca. 25,000 yr BP, from stalagmite, glacial, and lacustrine paleoclimatic data. Our results demonstrate a wet last glacial maximum (23 to 18 ka) in southwestern Mexico at 17.4 degrees N, a region that today is outside the influence of nortes or the westerlies. Wet conditions may be attributed to a moderately strong summer monsoon due to near-modern summer insolation values and a cooler eastern tropical Pacific Ocean akin to a modern La Niña-like state. We also document Heinrich stadial 1 and Younger Dryas monsoon weakening coincident with reduced North Atlantic thermohaline circulation, which implicates reduced onshore moisture flux due to a weaker and more southerly position of the Intertropical Convergence Zone. Mesoamerican rainfall was greatest during the early Holocene, and decreased non-linearly to the present in concert with decreasing local summer insolation. Following a relative mid-Holocene wet period, the last 4.5 ka are characterized by increasingly dry conditions, likely related to decreasing summer insolation and a greater El Niño frequency.

  14. The Periodic Pyramid

    Science.gov (United States)

    Hennigan, Jennifer N.; Grubbs, W. Tandy

    2013-01-01

    The chemical elements present in the modern periodic table are arranged in terms of atomic numbers and chemical periodicity. Periodicity arises from quantum mechanical limitations on how many electrons can occupy various shells and subshells of an atom. The shell model of the atom predicts that a maximum of 2, 8, 18, and 32 electrons can occupy…

  15. Subtropical atlantic climate studies: introduction.

    Science.gov (United States)

    Molinari, R L; Maul, G A; Chew, F; Wilson, W D; Busheell, M; Mayer, D; Leaman, K; Schott, F; Lee, T; Zantopp, R; Larsen, J C; Sanford, T B

    1985-01-18

    This report is an introduction to the accompanying collection of reports that present the results of a 2-year period of intensive monitoring of the Florida Current. Both direct observing systems (ship-deployed current profilers and moored current meters) and indirect observing systems (coastal tide gauge stations, bottom pressure gauge arrays, a submarine cable, acoustic arrays, and radar installations) were used to measure temperature and volume transport. PMID:17742098

  16. The site of net absorption of Ca from the intestinal tract of growing pigs and effect of phytic acid, Ca level and Ca source on Ca digestibility.

    Science.gov (United States)

    González-Vega, J Caroline; Walk, Carrie L; Liu, Yanhong; Stein, Hans H

    2014-01-01

    An experiment was conducted to test the hypothesis that the standardised digestibility of Ca in calcium carbonate and Lithothamnium calcareum Ca is not different regardless of the level of dietary Ca, and that phytic acid affects the digestibility of Ca in these two ingredients to the same degree. The objectives were to determine where in the intestinal tract Ca absorption takes place and if there are measurable quantities of basal endogenous Ca fluxes in the stomach, small intestine or large intestine. Diets contained calcium carbonate or L. calcareum Ca as the sole source of Ca, 0% or 1% phytic acid and 0.4% or 0.8% Ca. A Ca-free diet was also formulated and used to measure endogenous fluxes and losses of Ca. Nine growing pigs (initial body weight 23.8 ± 1.3 kg) were cannulated in the duodenum and in the distal ileum, and faecal, ileal and duodenal samples were collected. Duodenal endogenous fluxes of Ca were greater (p interaction, p < 0.05). The standardised duodenal digestibility (SDD), standardised ileal digestibility (SID) and standardised total tract digestibility (STTD) of Ca were not different if calcium carbonate was the source of dietary Ca. However, the STTD of Ca in L. calcareum Ca was greater (p < 0.05) than the SID and SDD of Ca. The SDD, SID and STTD of Ca in calcium carbonate were greater (p < 0.05) than those of L. calcareum Ca. In conclusion, under the conditions of this experiment, standardised digestibility of Ca is not affected by the level of phytic acid, but may be affected by dietary Ca level depending on the Ca source. Calcium from calcium carbonate is mostly absorbed before the duodenum, but Ca from L. calcareum Ca is mostly absorbed in the jejunum and ileum. PMID:24646151

  17. Daily rhythmicity of clock gene transcripts in atlantic cod fast skeletal muscle.

    Directory of Open Access Journals (Sweden)

    Carlo C Lazado

    Full Text Available The classical notion of a centralized clock that governs circadian rhythmicity has been challenged with the discovery of peripheral oscillators that enable organisms to cope with daily changes in their environment. The present study aimed to identify the molecular clock components in Atlantic cod (Gadus morhua and to investigate their daily gene expression in fast skeletal muscle. Atlantic cod clock genes were closely related to their orthologs in teleosts and tetrapods. Synteny was conserved to varying degrees in the majority of the 18 clock genes examined. In particular, aryl hydrocarbon receptor nuclear translocator-like 2 (arntl2, RAR-related orphan receptor A (rora and timeless (tim displayed high degrees of conservation. Expression profiling during the early ontogenesis revealed that some transcripts were maternally transferred, namely arntl2, cryptochrome 1b and 2 (cry1b and cry2, and period 2a and 2b (per2a and per2b. Most clock genes were ubiquitously expressed in various tissues, suggesting the possible existence of multiple peripheral clock systems in Atlantic cod. In particular, they were all detected in fast skeletal muscle, with the exception of neuronal PAS (Per-Arnt-Single-minded domain-containing protein (npas1 and rora. Rhythmicity analysis revealed 8 clock genes with daily rhythmic expression, namely arntl2, circadian locomotor output cycles kaput (clock, npas2, cry2, cry3 per2a, nuclear receptor subfamily 1, group D, member 1 (nr1d1, and nr1d2a. Transcript levels of the myogenic genes myogenic factor 5 (myf5 and muscleblind-like 1 (mbnl1 strongly correlated with clock gene expression. This is the first study to unravel the molecular components of peripheral clocks in Atlantic cod. Taken together, our data suggest that the putative clock system in fast skeletal muscle of Atlantic cod has regulatory implications on muscle physiology, particularly in the expression of genes related to myogenesis.

  18. Impact of observed North Atlantic multidecadal variations to European summer climate: a linear baroclinic response to surface heating

    Science.gov (United States)

    Ghosh, Rohit; Müller, Wolfgang A.; Baehr, Johanna; Bader, Jürgen

    2016-07-01

    The observed prominent multidecadal variations in the central to eastern (C-E) European summer temperature are closely related to the Atlantic multidecadal variability (AMV). Using the Twentieth Century Reanalysis project version 2 data for the period of 1930-2012, we present a mechanism by which the multidecadal variations in the C-E European summer temperature are associated to a linear baroclinic atmospheric response to the AMV-related surface heat flux. Our results suggest that over the north-western Atlantic, the positive heat flux anomaly triggers a surface baroclinic pressure response to diabatic heating with a negative surface pressure anomaly to the east of the heat source. Further downstream, this response induces an east-west wave-like pressure anomaly. The east-west wave-like response in the sea level pressure structure, to which we refer as North-Atlantic-European East West (NEW) mode, is independent of the summer North Atlantic Oscillation and is the principal mode of variations during summer over the Euro-Atlantic region at multidecadal time scales. The NEW mode causes warming of the C-E European region by creating an atmospheric blocking-like situation. Our findings also suggest that this NEW mode is responsible for the multidecadal variations in precipitation over the British Isles and north-western Europe.

  19. Mammal occurrence and roadkill in two adjacent ecoregions (Atlantic Forest and Cerrado in south-western Brazil

    Directory of Open Access Journals (Sweden)

    Nilton C. Cáceres

    2010-10-01

    Full Text Available This paper examines the frequencies of mammal roadkill in two adjacent biogeographic ecoregions (Atlantic Forest and Cerrado of Brazil. Mammals were recorded during a seven-year period and over 3,900 km of roads, in order to obtain data for frequencies of species in habitats (sites and frequencies of species killed by cars on roads. Sites (n = 80 within ecoregions (Cerrado, n = 57; Atlantic Forest, n = 23 were searched for records of mammals. Species surveyed in the entire region totaled 33, belonging to nine orders and 16 families. In the Cerrado, 31 species were recorded in habitats; of these, 25 were found dead on roads. In the Atlantic Forest ecoregions, however, we found 21 species in habitats, 16 of which were also found dead on roads. There was no overall significant difference between ecoregions for frequencies of occurrence in habitats or for roadkills, but there were differences between individual species. Hence, anteaters were mostly recorded in the Cerrado ecoregion, whereas caviomorph rodents tended to be more frequent in the Atlantic Forest ecoregion (seen mainly by roadkills. The greater number of species (overall and threatened and the greater abundance of species records in the Cerrado suggest that this ecoregion has a greater biodiversity and is better conserved than the Atlantic Forest ecoregion, in the state of Mato Grosso do Sul, south-western Brazil.

  20. A model study of the seasonal and long term North Atlantic surface pCO2 variability

    Directory of Open Access Journals (Sweden)

    C. Heinze

    2011-10-01

    Full Text Available A coupled biogeochemical-physical ocean model is used to study the long term variations of surface pCO2 in the North Atlantic Ocean. The model agrees well with recent underway pCO2 observations from the Surface Ocean CO2 Atlas (SOCAT database in various locations in the North Atlantic. The distinct seasonal cycles observed at different parts of the North Atlantic are well reproduced by the model. In most regions except the subpolar domain, the recent observed trends in pCO2 and air–sea carbon fluxes are also simulated by the model. Over a long period between 1960–2008, the primary mode of surface pCO2 variability is dominated by the increasing trend associated with the invasion of anthropogenic CO2 into the ocean. We show that, to first order, the ocean surface circulation and air–sea heat flux patterns can explain the spatial variability of this dominant increasing trend. Regions with strong surface mass transport and negative air–sea heat flux have the tendency to maintain lower surface pCO2. Regions of surface convergence and mean positive air–sea heat flux such as the subtropical gyre and the western subpolar gyre have faster increase in pCO2 over a long term period. The North Atlantic Oscillation (NAO plays a major role in controlling the variability occurring at interannual to decadal time scales. The NAO predominantly influences surface pCO2 in the North Atlantic by changing the physical properties of the North Atlantic water masses, particularly by perturbing the temperature and dissolved inorganic carbon in the surface ocean. We show that present underway observations are valuable for both calibrating the model, as well as for improving our understanding of the regionally heterogeneous variability of surface pCO2. In addition, they can be important for detecting any long term change in the regional carbon cycle due to ongoing climate change.

  1. Mechanisms of meridional transport processes in the tropical Atlantic; Mechanismen meridionaler Transportprozesse im tropischen Atlantik

    Energy Technology Data Exchange (ETDEWEB)

    Kroeger, J.

    2001-07-01

    Meridional transport processes of water masses and tracers in the subtropical and tropical Atlantic are investigated using a regional eddy resolving model of the wind driven and thermohaline circulation. Analytical emphasis is on float simulations in the model which, complementary to Eulerian means, represent the Lagrangian view and give further insight into the spreading and pathways of characteristic water masses in this area. In the tropics and subtropics shallow 3-dimensional circulation cells are superimposed on the northward warm water transfer within the deep reaching thermohaline overturning cell (MOC) as part of the global ''Conveyor Belt''. Under present-day climate conditions the model shows that the equatorial thermocline is exclusively ventilated by subsurface flow within the tropical-subtropical cell (STC) of the South Atlantic. Only with a prescribed ''Conveyor-off''-Mode the STC of the North Atlantic contributes to this ventilation process with equal amounts. Throughout the year the interhemispheric transport of surface and central water masses of South Atlantic origin into the Caribbean Sea is dominated by zonal detours to the east as a consequence of the interplay of several retroflection events occuring in the North Atlantic. The eulerian mean flow field in the deep layer postulates the interhemispheric mass transport into the South Atlantic to be confined entirely to the western boundary, whereas Lagrangian means indicate intermittent eastward excursions along the equator, related to seasonally alternating zonal currents due to long Rossby waves. It was suggested that the observed characteristic eastward maximum of tracer concentrations along the equator is a consequence of rectifying effects of single or interacting equatorial waves. The model does not validate this hypothesis. The response to transport anomalies of subpolar origin and long periodicity is subject to different time-scales in both

  2. Hydrology of surface waters and thermohaline circulation during the last glacial period

    International Nuclear Information System (INIS)

    Sedimentological studies on oceanic cores from the north Atlantic have revealed, over the last glacial period, abrupt climatic changes with a periodicity of several thousand years which contrasts strongly with the glacial-interglacial periodicity (several tens of thousand years). These periods of abrupt climate changes correspond to massive icebergs discharges into the north Atlantic. The aim of this work was to study the evolution of the thermohaline circulation in relation to these episodic iceberg discharges which punctuated the last 60 ka. To reconstruct the oceanic circulation in the past, we have analysed oxygen and carbon stable isotopes on benthic foraminifera from north Atlantic deep-sea cores. First of all, the higher temporal resolution of sedimentary records has enabled us to establish a precise chrono-stratigraphy for the different cores. Then, we have shown the close linkage between surface water hydrology and deep circulation, giving evidence of the sensibility of thermohaline circulation to melt water input in the north Atlantic ocean. Indeed, changes in deep circulation are synchronous from those identified in surface waters and are recorded on a period which lasted ∼ 1500 years. Deep circulation reconstructions, before and during a typical iceberg discharge reveal several modes of circulation linked to different convection sites at the high latitudes of the Atlantic basin. Moreover, the study of the last glacial period gives the opportunity to differentiate circulation changes due to the external forcing (variations of the orbital parameters) and those linked to a more local forcing (icebergs discharges). 105 refs., 50 figs., 14 tabs., 4 appends

  3. Mg/Ca thermometry in planktic foraminifera: Improving paleotemperature estimations for G. bulloides and N. pachyderma left

    Science.gov (United States)

    Vázquez Riveiros, Natalia; Govin, Aline; Waelbroeck, Claire; Mackensen, Andreas; Michel, Elisabeth; Moreira, Santiago; Bouinot, Thomas; Caillon, Nicolas; Orgun, Ayche; Brandon, Margaux

    2016-04-01

    Planktic foraminiferal Mg/Ca ratios have become a fundamental seawater temperature proxy in past climate reconstructions, due to the temperature dependence of Mg uptake into foraminiferal calcite. However, empirical calibrations for single species from methodologically consistent data are still lacking. Here we present species-specific calibrations of Mg/Ca versus calcification temperature for two commonly used species of planktic foraminifera: Globigerina bulloides and Neogloboquadrina pachyderma left, based on a series of Southern Ocean and North Atlantic core tops. Combining these new data with previously published data, we derive an integrated G. bulloides Mg/Ca-temperature calibration for mid and high latitudes of both hemispheres between 2 and 18°C, where Mg/Ca = 1.006 ± 0.032 * e0.065 ± 0.003*Tiso (R2 = 0.82). G. bulloides is found to calcify deeper in the Southern Ocean (˜ 200 m) than in the North Atlantic (top 50 m). We also propose a Mg/Ca temperature calibration to describe the temperature response in N. pachyderma left that calcified away from the influence of sea ice in the Southern Ocean, valid between ˜ -1 and 9°C, of the form Mg/Ca = 0.580 ± 0.016 * e0.084 ± 0.006*Tiso (R2 = 0.70). These calibrations account for uncertainties on Mg/Ca measurements and calcification temperature that were carefully estimated and propagated using Monte Carlo iterations. The 1σ propagated error in Mg/Ca-derived temperatures is 1.1°C for G. bulloides and 0.9°C for N. pachyderma left for the presented data sets. Geographical extension of genotypes must be assessed when choosing to develop regional or global calibrations.

  4. Tectonic forcing of early to middle jurassic seawater Sr/Ca

    DEFF Research Database (Denmark)

    Ullmann, Clemens Vinzenz; Hesselbo, Stephen P.; Korte, Christoph

    2013-01-01

    The Jurassic Period (ca. 201–145 Ma) is marked by fundamental reorganizations of paleogeography, paleoceanography, ecosystems, and the progressive shift from aragonite to calcite as the favored marine biogenic carbonate polymorph. Sr/Ca ratios of well-preserved Jurassic oysters and belemnites fro...

  5. Reduced Anxiety in Forensic Inpatients after a Long-Term Intervention with Atlantic Salmon

    Directory of Open Access Journals (Sweden)

    Anita L. Hansen

    2014-11-01

    Full Text Available The aim of the present study was to investigate the effects of Atlantic salmon consumption on underlying biological mechanisms associated with anxiety such as heart rate variability (HRV and heart rate (HR as well as a measure of self-reported anxiety. Moreover, these biological and self-reported outcome measures were investigated in relation to specific nutrients; vitamin D status, eicosapentaenoic acid (EPA and docosahexaenoic acid (DHA. Ninety-five male forensic inpatients were randomly assigned into a Fish (Atlantic salmon three times per week from September to February or a Control group (alternative meal, e.g., chicken, pork, or beef three times per week during the same period. HRV measured as the root mean square of successive differences (rMSSD, HR, state- and trait-anxiety (STAI, were assessed before (pre-test and at the end of the 23 weeks dietary intervention period (post-test. The Fish group showed significant improvements in both rMSSD and HR. The Fish group also showed significant decreases in state-anxiety. Finally, there was a positive relationship between rMSSD and vitamin D status. The findings suggest that Atlantic salmon consumption may have an impact on mental health related variables such as underlying mechanisms playing a key role in emotion-regulation and state-anxiety.

  6. Punctuated Shutdown of Atlantic Meridional Overturning Circulation during Greenland Stadial 1

    Science.gov (United States)

    Hogg, Alan; Southon, John; Turney, Chris; Palmer, Jonathan; Bronk Ramsey, Christopher; Fenwick, Pavla; Boswijk, Gretel; Friedrich, Michael; Helle, Gerhard; Hughen, Konrad; Jones, Richard; Kromer, Bernd; Noronha, Alexandra; Reynard, Linda; Staff, Richard; Wacker, Lukas

    2016-05-01

    The Greenland Stadial 1 (GS-1; ~12.9 to 11.65 kyr cal BP) was a period of North Atlantic cooling, thought to have been initiated by North America fresh water runoff that caused a sustained reduction of North Atlantic Meridional Overturning Circulation (AMOC), resulting in an antiphase temperature response between the hemispheres (the ‘bipolar seesaw’). Here we exploit sub-fossil New Zealand kauri trees to report the first securely dated, decadally-resolved atmospheric radiocarbon (14C) record spanning GS-1. By precisely aligning Southern and Northern Hemisphere tree-ring 14C records with marine 14C sequences we document two relatively short periods of AMOC collapse during the stadial, at ~12,920-12,640 cal BP and 12,050-11,900 cal BP. In addition, our data show that the interhemispheric atmospheric 14C offset was close to zero prior to GS-1, before reaching ‘near-modern’ values at ~12,660 cal BP, consistent with synchronous recovery of overturning in both hemispheres and increased Southern Ocean ventilation. Hence, sustained North Atlantic cooling across GS-1 was not driven by a prolonged AMOC reduction but probably due to an equatorward migration of the Polar Front, reducing the advection of southwesterly air masses to high latitudes. Our findings suggest opposing hemispheric temperature trends were driven by atmospheric teleconnections, rather than AMOC changes.

  7. Temperature Oscillation from the Western Equatorial Atlantic in the Last 40000 Years

    Science.gov (United States)

    Santos, T. P.; Albuquerque, A.; Barbosa, C. F.; Lessa, D.; Trond, D.; Belem, A. L.

    2011-12-01

    The Atlantic Meridional Overturning Circulation (AMOC), through the North Brazil Current (NBC), has a significant role for the budget of heat and salt of the North Atlantic and changes on its strength are known to have profound impacts on global climate. Studies based on modeling suggested that, from annual to multi-decadal time scales, a slowdown of AMOC causes a deepening of the thermocline in the tropical Atlantic. In this work, we show a surface temperature oscillation reconstruction based on Modern Analog Technique (using the software Paleoanalogs 3.0.) employing planktonic foraminifera assemblage from a multicore collected on Western Equatorial Atlantic for the last 40 kyr. The main species were the shallow and warm dwelling Globigerinoides ruber (pink and white forms), G. sacculifer and Globigerinella siphonifera followed by the deep dwelling Globorotalia truncatulinoides (left and right coiling) and Globorotalia menardii. Our surface temperature reconstruction evidence sea surface temperatures around 2 degree Celsius colder than present with a pronounced warming phase during the Last Glacial Maximum. The productivity-related species Globigerinita glutinata and Neogloboquadrina dutertrei presented a strong reduction in number of individuals at the end of this period as well as at early-Holocene, probably due to stratification of water column. The thermocline-dwelling Globorotalia menardii was poorly represented during the glacial period due to thermocline deepening on the region, but it reached higher percentages drive by early-Holocene oceanic ventilation. This warming is synchronous with increase intensity of SE trade winds, producing more humid conditions in northeast Brazil hinterland and with prolonged retroflection of the North Brazil Current, which reduced the cross-equatorial transport of heat and salinity. Moreover, a warm South Atlantic Ocean resulted in a southward migration of the ITCZ and contributed for the curtailment of cross-equatorial heat

  8. Impending collapse of bluefin tuna in the northeast Atlantic and Mediterranean

    DEFF Research Database (Denmark)

    MacKenzie, Brian; Mosegaard, Henrik; Rosenberg, Andrew A.

    2009-01-01

    The abundance of bluefin tuna, Thunnus thynnus, in the east Atlantic and Mediterranean has declined in recent decades. The International Commission for the Conservation of Atlantic Tunas (ICCAT), the regional bluefin tuna management authority, has developed a plan to promote recovery by 2022, while...... still permitting fishing to continue during the period 2008-2010. Here we predict that the adult population in 2011 will likely be 75% lower relative to 2005 and that quotas in some intervening years will allow the fishery to capture legally all of the adult fish. Population demographics (proportion...... of older fish and repeat spawners in population) indicate that buffering capacity against years of poor reproduction has been reduced. This population is at risk of collapse (90% decline in adult biomass within three generations, the criterion used by the IUCN for defining populations as Critically...

  9. NORTH ATLANTIC OSCILLATION AND RAINFALL VARIABILITY ON THE SOUTHERN COAST OF THE MEDITERRANEAN

    Directory of Open Access Journals (Sweden)

    BENOIT L.

    2014-03-01

    Full Text Available Regions of the south-western Mediterranean basin were the focus of many studies since they have experienced a series of climate changes. The contribution of the North Atlantic Oscillation in precipitations is required to be analyzed with the aim to understand the possible hydrological changes. In this way, an analysis of precipitations along the coast of central Maghreb (Morocco, Algeria and Tunisia was carried. The present analysis was performed using (1 The graphical method of information processing and (2 wavelet transform technique. Results can be summarized as the following. Results show a high drought observed in all studied regions since the med-eighties and a return of the wet period since year 2003. Moreover, we demonstrate significant links of precipitations with the North Atlantic Oscillation

  10. Numerical evaluation of the wave energy resource along the Atlantic European coast

    Science.gov (United States)

    Guedes Soares, C.; Bento, A. Rute; Gonçalves, Marta; Silva, Dina; Martinho, Paulo

    2014-10-01

    In the present paper a hindcast system is applied to the analysis of the Atlantic European coast as a whole with specific nestings for sites of interest in each country. The areas included in this study were: Ireland west coast, UK South Western coast, France west coast, northern Spain and Canary Islands and Portugal's continental coast. Two contemporary spectral models were used: WaveWatch III for wave generation, covering almost the entire North Atlantic basin, which outputs are then used as boundary conditions for SWAN which simulates wave transformation in coastal areas. Wind fields were taken from the ERA Interim data base. Results are validated against buoy data. These validations allowed a reformulation, when needed, of the model's configurations in order to better tune its outcomes to the real data. Using the energy transport vectors given by SWAN, the wave power is afterwards calculated and an energy resource assessment is done for a period of several years.

  11. Excitation of Annual Polar Motion by the Pacific, Atlantic and Indian Oceans

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The global oceans play important roles in exciting the annual polar motion besides the atmosphere. However, it is still unclear about how large the regional oceans contribute to the annual polar motion. We investigate systemically the contributions of the Pacific, Atlantic and Indian Oceans to the excitation of the annual polar motion, based on the output data of ocean current velocity field and ocean bottom pressure field from "Estimating the Circulation and Climate of the Ocean (ECCO)" ocean circulation model over the period 1993-2005. The result shows that due to its particular location and shape, the Atlantic Ocean makes a less significant contribution to the x-component of the annual polar motion excitation than the Pacific and Indian Oceans, while all these three oceans contribute to the y-component of the annual polar motion excitation to some extent.

  12. Soft spin dipole giant resonances in 40Ca

    CERN Document Server

    Stuhl, L; Csatlos, M; Marketin, T; Litvinova, E; Adachi, T; Algora, A; Daeven, J; Estevez, E; Fujita, H; Fujita, Y; Guess, C; Gulyas, J; Hatanaka, K; Hirota, K; Ong, H J; Ishikawa, D; Matsubara, H; Meharchand, R; Molina, F; Okamura, H; Perdikakis, G; Rubio, B; Scholl, C; Suzuki, T; Susoy, G; Tamii, A; Thies, J; Zegers, R; Zenihiro, J

    2013-01-01

    High resolution experimental data has been obtained for the 40,42,44,48Ca(3He,t)Sc charge exchange reaction at 420 MeV beam energy, which favors the spin-isospin excitations. The measured angular distributions were analyzed for each state separately, and the relative spin dipole strength has been extracted for the first time. The low-lying spin-dipole strength distribution in 40Sc shows some interesting periodic gross feature. It resembles to a soft, dumped multi-phonon vibrational band with $\\hbar\\omega$= 1.8 MeV, which might be associated to pairing vibrations around $^{40}$Ca.

  13. Existence of the classical solution and almost periodic solution for the Camassa-Holm type equations

    Institute of Scientific and Technical Information of China (English)

    YANG Ling'e; GUO Boling

    2004-01-01

    Using Banach fixed point theorem and a priori estimate,the existence of periodic and almost periodic solutions of Ca massa-Holm type equation with a nonlinear boundary condition are respectively proved when g(x,t)is periodic or almost periodic function of time t.

  14. On The Source Of The 25 November 1941 - Atlantic Tsunami

    Science.gov (United States)

    Baptista, M. A.; Lisboa, F. B.; Miranda, J. M. A.

    2015-12-01

    In this study we analyze the tsunami recorded in the North Atlantic following the 25 November 1941 earthquake. The earthquake with a magnitude of 8.3, located on the Gloria Fault, was one of the largest strike slip events recorded. The Gloria fault is a 500 km long scarp in the North Atlantic Ocean between 19W and 24W known to be a segment of the Eurasia-Nubia plate boundary between Iberia and the Azores. Ten tide stations recorded the tsunami. Six in Portugal (mainland, Azores and Madeira Islands), two in Morocco, one in the United Kingdom and one in Spain (Tenerife-Canary Islands). The tsunami waves reached Azores and Madeira Islands less than one hour after the main shock. The tide station of Casablanca (in Morocco) recorded the maximum amplitude of 0.54 m. All amplitudes recorded are lower than 0.5 m but the tsunami reached Portugal mainland in high tide conditions where the sea flooded some streets We analyze the 25 November 1941 tsunami data using the tide-records in the coasts of Portugal, Spain, Morocco and UK to infer its source. The use of wavelet analysis to characterize the frequency content of the tide-records shows predominant periods of 9-13min e 18-22min. A preliminary location of the tsunami source location was obtained Backward Ray Tracing (BRT). The results of the BRT technique are compatible with the epicenter location of the earthquake. We compute empirical Green functions for the earthquake generation area, and use a linear shallow water inversion technique to compute the initial water displacement. The comparison between forward modeling with observations shows a fair agreement with available data. This work received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 603839 (Project ASTARTE - Assessment, Strategy and Risk Reduction for Tsunamis in Europe)"

  15. The Aptian evaporites of the South Atlantic: a climatic paradox?

    Directory of Open Access Journals (Sweden)

    A.-C. Chaboureau

    2012-01-01

    Full Text Available For a long time, evaporitic sequences have been interpreted as indicative of an arid climate. Such systematic interpretations led to the suggestion that the central segment of the South Atlantic (20°–0° was characterized by an arid climate during the upper Aptian. Indeed, synchronous to this period that corresponds to the rifting and to the opening of this part of the South Atlantic, a large evaporitic sequence spreads out from the equator to 20° S. Using the fully ocean atmosphere coupled model FOAM, we test the potential for the Aptian geography to produce an arid area over the central segment. Sensitivity to the altitude of the rift shoulders separating the Africa and the South America cratons, to the water depth of the central segment and to the drainage pattern have been performed. Using seawater salinity as a diagnostic, our simulations show that the southern part of the central segment is characterized by very high salinity in the case of catchment areas draining the water out of the central segment. Conversely, whatever the boundary conditions used, the northern part of the central segment remains humid and salinities are very low. Hence, we conclude that the evaporites deposited in the southern part of the central segment may have been controlled by the climate favouring aridity and high saline waters. In contrast, the evaporites of the northern part can hardly be reconciled with the climatic conditions occurring there and may be due to hydrothermal sources. Our interpretations are in agreement with the gradient found in the mineralogical compositions of the evaporites from the north to the south, i.e. the northern evaporites are at least 4 times more concentrated than the southern one.

  16. Horizontal and vertical distribution of mesozooplankton species richness and composition down to 2,300 m in the southwest Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    Sérgio L.C. Bonecker

    2014-10-01

    Full Text Available We describe the species richness, distribution and composition of mesozooplankton over the continental shelf and slope, and in the water masses in the Campos Basin, southwest Atlantic Ocean. We analyzed the mesozooplankton from two oceanographic cruises (rainy and dry seasons, 2009 with samples taken in five different water masses from the surface to 2,300 m depth. In the Subsurface Water (SS, in both sampling periods, more species were recorded over the slope (rainy: 100; dry: 128 than the continental shelf (rainy: 97; dry: 104. Over the slope, species richness decreased with increasing depth: the highest values were observed in the South Atlantic Central Water (SACW, and the lowest values in the North Atlantic Deep Water (NADW, in both sampling periods. We recorded 262 species in 10 groups (Hydrozoa, Siphonophora, Ctenophora, Branchiopoda, Copepoda, Euphausiacea, Decapoda, Chaetognatha, Appendicularia e Thaliacea, with 13 new occurrences for the southwest Atlantic. Copepoda was the group with the highest species richness, containing 138 species. In both periods, the samples from SS, SACW and Antarctic Intermediate Water (AAIW/Upper Circumpolar Deep Water (UCDW were clustered in different faunistic zones, based on species composition. This study confirmed that zooplankton richness in the southwest Atlantic Ocean is underestimated, and suggests that additional efforts must be directed toward a better understanding of this fairly unknown region.

  17. Calcification and growth processes in planktonic foraminifera complicate the use of B/Ca and U/Ca as carbonate chemistry proxies

    Science.gov (United States)

    Salmon, Kate H.; Anand, Pallavi; Sexton, Philip F.; Conte, Maureen

    2016-09-01

    Although boron and uranium to calcium ratios (B/Ca, U/Ca) in planktonic foraminifera have recently received much attention as potential proxies for ocean carbonate chemistry, the extent of a carbonate chemistry control on these ratios remains contentious. Here, we use bi-weekly sediment trap samples collected from the subtropical North Atlantic in combination with measured oceanographic data from the same location to evaluate the dominant oceanographic controls on B/Ca and U/Ca in three depth-stratified species of planktonic foraminifera. We also test the control of biological, growth-related, processes on planktonic foraminiferal B and U incorporation by using foraminifer test area density (μ g /μm2) (a monitor of test thickness) and test size from the same samples. B/Ca and U/Ca show little or no significant correlation with carbonate system parameters both within this study and in comparison with other published works. We provide the first evidence for a strong positive relationship between area density (test thickness) and B/Ca, and reveal that this is consistent in all species studied, suggesting a likely role for calcification in controlling boron partitioning into foraminiferal calcite. This finding is consistent with previous observations of less efficient discrimination against trace element 'impurities' (such as B), at higher calcification rates. We observe little or no dependency of B/Ca on test size. In marked contrast, we find that U/Ca displays a strong species-specific dependency on test size in all species, but no relationship with test thickness, implicating some other biological control (possibly related to growth), rather than a calcification control, on U incorporation into foraminiferal calcite. Our results caution against the use of B/Ca and U/Ca in planktonic foraminifera as reliable proxies for the ocean carbonate system and recommend that future work should concentrate on improving the mechanistic understanding of how planktonic

  18. CaWingz user's guide

    International Nuclear Information System (INIS)

    This document assumes that you have read and understood the Wingz user's manuals. CaWingz is an external Wingz program which, when combined with a set of script files, provides easy-to-use EPICS channel access interface functions for Wingz users. The external function run allows Wingz user to invoke any Unix processor within caWingz. Few additional functions for accessing static database field and monitoring of value change event is available for EPICS users after release 3.11. The functions, script files, and usage are briefly described in this document. The script files supplied here serve as examples only. Users are responsible for generating their own spreadsheet and script files. CaWingz communicates with IOC through channel access function calls

  19. Periodicity of chaotic solutions

    CERN Document Server

    Berezowski, Marek

    2016-01-01

    The scope of the paper is the analysis of the impact of flow reversal on the dynamics of cascades of reactors. Periodic and chaotic oscillations occur in the analyzed system. There is a dependence between the oscillation period of the state variable of the system without flow reversal and the recurrence period of windows of chaos in the steady-state diagram of the system with flow reversal.

  20. Modelling the future biogeography of North Atlantic zooplankton communities in response to climate change

    KAUST Repository

    Villarino, E

    2015-07-02

    Advances in habitat and climate modelling allow us to reduce uncertainties of climate change impacts on species distribution. We evaluated the impacts of future climate change on community structure, diversity, distribution and phenology of 14 copepod species in the North Atlantic. We developed and validated habitat models for key zooplankton species using continuous plankton recorder (CPR) survey data collected at mid latitudes of the North Atlantic. Generalized additive models (GAMs) were applied to relate the occurrence of species to environmental variables. Models were projected to future (2080–2099) environmental conditions using coupled hydroclimatix–biogeochemical models under the Intergovernmental Panel on Climate Change (IPCC) A1B climate scenario, and compared to present (2001–2020) conditions. Our projections indicated that the copepod community is expected to respond substantially to climate change: a mean poleward latitudinal shift of 8.7 km per decade for the overall community with an important species range variation (–15 to 18 km per decade); the species seasonal peak is expected to occur 12–13 d earlier for Calanus finmarchicus and C. hyperboreus; and important changes in community structure are also expected (high species turnover of 43–79% south of the Oceanic Polar Front). The impacts of the change expected by the end of the century under IPCC global warming scenarios on copepods highlight poleward shifts, earlier seasonal peak and changes in biodiversity spatial patterns that might lead to alterations of the future North Atlantic pelagic ecosystem. Our model and projections are supported by a temporal validation undertaken using the North Atlantic climate regime shift that occurred in the 1980s: the habitat model built in the cold period (1970–1986) has been validated in the warm period (1987–2004).

  1. Displaced fracture through the anterior atlantal synchondrosis

    Energy Technology Data Exchange (ETDEWEB)

    Thakar, Chrishan; Allibone, James [Royal National Orthopaedic Hospital NHS Trust, Department of Spinal Deformity, Stanmore, Middlesex (United Kingdom); Harish, Srinivasan [Royal National Orthopaedic Hospital NHS Trust, Department of Radiology, Stanmore, Middlesex (United Kingdom); Saifuddin, Asif [Royal National Orthopaedic Hospital NHS Trust, Department of Radiology, Stanmore, Middlesex (United Kingdom); University College, The Institute of Orthopaedics and Musculoskeletal Sciences, London (United Kingdom)

    2005-09-01

    In the acute setting, accurate radiological interpretation of paediatric cervical spine trauma can be difficult due to a combination of normal variants and presence of multiple synchondroses. We present a rare case of a fracture through the anterior atlantal synchondrosis in a paediatric spine. A five-year-old boy, who fell backwards onto the top of his head while swinging across on a monkey bar frame, presented with neck pain, cervical muscle spasm and decreased right lateral rotation and extension of his neck. Computed tomography showed a displaced diastatic fracture through right anterior atlantal synchondrosis. There are only 12 cases of paediatric C1 fractures reported in the world literature. The importance of considering this diagnosis in the appropriate clinical setting, and the normal variants in the paediatric atlas that can cause diagnostic dilemma to the interpreting radiologist, are discussed in this case report. (orig.)

  2. Wind Stress Increases Glacial Atlantic Overturning

    Science.gov (United States)

    Muglia, J.; Schmittner, A.

    2015-12-01

    Previous Paleoclimate Model Intercomparison Project (PMIP) simulations of the Last Glacial Maximum (LGM) Atlantic Meridional Overturning Circulation (AMOC) showed ambiguous results on transports and structure. Here we analyze the most recent PMIP3 models, which show a consistent increase (on average by 41%) and deepening (580 m) of the AMOC for all models with respect to pre-industrial control (PIC) simulations (see Figure), in contrast to some reconstructions. Changes in wind stress alone lead to similar AMOC responses in a climate-ocean circulation model, suggesting that atmospheric circulation changes in the North Atlantic due to the presence of ice sheets are an important control in the PMIP3 models' LGM response. These results improve our understanding of the LGM AMOC's driving forces and are relevant for the evaluation of models that are used in the IPCC's Assessment Reports for future climate projections, as well as for the currently ongoing design of the next round of PMIP.

  3. Coherent water transport across the South Atlantic

    CERN Document Server

    Wang, Y; Beron-Vera, F J

    2015-01-01

    The role of mesoscale eddies in transporting Agulhas leakage is investigated using a recent technique from nonlinear dynamical systems theory applied on geostrophic currents inferred from the over two-decade-long satellite altimetry record. Eddies are found to acquire material coherence away from the Agulhas retroflection, near the Walvis Ridge in the South Atlantic. Yearly, 1 to 4 coherent material eddies are detected with diameters ranging from 40 to 280 km. A total of 23 eddy cores of about 50 km in diameter and with at least 30% of their contents traceable into the Indian Ocean were found to travel across the subtropical gyre with minor filamentation. No more than 5\\% of such cores pour their contents on the North Brazil Current. While ability of eddies to carry Agulhas leakage northwestward across the South Atlantic is supported by our analysis, this is more restricted than suggested by earlier ring transport assessments.

  4. Routes of Ca2+ Shuttling during Ca2+ Oscillations: FOCUS ON THE ROLE OF MITOCHONDRIAL Ca2+ HANDLING AND CYTOSOLIC Ca2+ BUFFERS.

    Science.gov (United States)

    Pecze, László; Blum, Walter; Schwaller, Beat

    2015-11-20

    In some cell types, Ca(2+) oscillations are strictly dependent on Ca(2+) influx across the plasma membrane, whereas in others, oscillations also persist in the absence of Ca(2+) influx. We observed that, in primary mesothelial cells, the plasmalemmal Ca(2+) influx played a pivotal role. However, when the Ca(2+) transport across the plasma membrane by the "lanthanum insulation method" was blocked prior to the induction of the serum-induced Ca(2+) oscillations, mitochondrial Ca(2+) transport was found to be able to substitute for the plasmalemmal Ca(2+) exchange function, thus rendering the oscillations independent of extracellular Ca(2+). However, in a physiological situation, the Ca(2+)-buffering capacity of mitochondria was found not to be essential for Ca(2+) oscillations. Moreover, brief spontaneous Ca(2+) changes were observed in the mitochondrial Ca(2+) concentration without apparent changes in the cytosolic Ca(2+) concentration, indicating the presence of a mitochondrial autonomous Ca(2+) signaling mechanism. In the presence of calretinin, a Ca(2+)-buffering protein, the amplitude of cytosolic spikes during oscillations was decreased, and the amount of Ca(2+) ions taken up by mitochondria was reduced. Thus, the increased calretinin expression observed in mesothelioma cells and in certain colon cancer might be correlated to the increased resistance of these tumor cells to proapoptotic/pronecrotic signals. We identified and characterized (experimentally and by modeling) three Ca(2+) shuttling pathways in primary mesothelial cells during Ca(2+) oscillations: Ca(2+) shuttled between (i) the endoplasmic reticulum (ER) and mitochondria, (ii) the ER and the extracellular space, and (iii) the ER and cytoplasmic Ca(2+) buffers.

  5. CA on CD评析

    Institute of Scientific and Technical Information of China (English)

    周秀会

    2007-01-01

    结合作者使用 CA On CD 的经验和体会,全面而具体地分析了 CA on CD 的使用功能,明确了其优点及不足之处,同时,针对这些不足之处进行了探索和尝试,提出了利用检索技巧解决这些不足之处的方法。并结合实例详细说明。

  6. Endoplasmic Reticulum Ca(2+) Handling and Apoptotic Resistance in Tumor-Derived Endothelial Colony Forming Cells.

    Science.gov (United States)

    Poletto, Valentina; Dragoni, Silvia; Lim, Dmitry; Biggiogera, Marco; Aronica, Adele; Cinelli, Mariapia; De Luca, Antonio; Rosti, Vittorio; Porta, Camillo; Guerra, Germano; Moccia, Francesco

    2016-10-01

    Truly endothelial progenitor cells (EPCs) can be mobilized from bone marrow to support the vascular network of growing tumors, thereby sustaining the metastatic switch. Endothelial colony forming cells (ECFCs) are the only EPC subtype belonging to the endothelial phenotype and capable of incorporating within neovessels. The intracellular Ca(2+) machinery plays a key role in ECFC activation and is remodeled in renal cellular carcinoma-derived ECFCs (RCC-ECFCs). Particularly, RCC-ECFCs seems to undergo a drop in endoplasmic reticulum (ER) Ca(2+) concentration ([Ca(2+) ]ER ). This feature is remarkable when considering that inositol-1,4,5-trisphosphate (InsP3 )-dependent ER-to-mitochondria Ca(2+) transfer regulates the intrinsic apoptosis pathway. Herein, we sought to assess whether: (1) the [Ca(2+) ]ER and the InsP3 -induced ER-mitochondria Ca(2+) shuttle are reduced in RCC-ECFCs; and (2) the dysregulation of ER Ca(2+) handling leads to apoptosis resistance in tumor-derived cells. RCC-ECFCs displayed a reduction both in [Ca(2+) ]ER and in the InsP3 -dependent mitochondrial Ca(2+) uptake, while they expressed normal levels of Bcl-2 and Bak. The decrease in [Ca(2+) ]ER was associated to a remarkable ER expansion in RCC-ECFCs, which is a hallmark of ER stress, and did not depend on the remodeling of the Ca(2+) -transporting and the ER Ca(2+) -storing systems. As expected, RCC-ECFCs were less sensitive to rapamycin- and thapsigargin-induced apoptosis; however, buffering intracellular Ca(2+) levels with BAPTA dampened apoptosis in both cell types. Finally, store-operated Ca(2+) entry was seemingly uncoupled from the apoptotic machinery in RCC-ECFCs. Thus, the chronic underfilling of the ER Ca(2+) pool could confer a survival advantage to RCC-ECFCs and underpin RCC resistance to pharmacological treatment. J. Cell. Biochem. 117: 2260-2271, 2016. © 2016 Wiley Periodicals, Inc.

  7. Alterations of Intracellular Ca2+ Concentration and Ultrastructure in Spruce Apical Bud Cells during Seasonal Transition

    Institute of Scientific and Technical Information of China (English)

    Jian Lingcheng; Sun Delan; Deng Jiangming; Song Yanmei; Paul H. Li

    2004-01-01

    Potassium antimonite was used to localize Ca2+ in the apical bud cells of spruce from July 1999 to May 2000. During the period of active growth (July 14), Calcium precipitates, an indication of Ca2+ localization, were mainly distributed in vacuoles, intercellular spaces and cell walls. Few Ca2+ deposits localized in the cytosol and nucleus, showing a low level of the cytosolic and nuclear Ca2+ concentration in the warm summer. In August, some Ca2+ deposits appeared in the cytosol and nuclei, indicating that Ca2+ influx occurred in the cytosol and nucleus as the day length became shorter. From September to November, high levels of the cytosolic and nuclear Ca2+ remained. During the mid-winter (December and January), the distribution of Ca2+ deposits and the ultrastructures in the cells were altered dramatically. Plasmolysis occurred in many cells due to the protoplasmic dehydration. In addition plasmalemma invagination and nuclear chromatin aggregation also occurred. A large number of Ca2+ deposits appeared in the space between the plasmalemma and the cell wall. And also some Ca2+ deposits were distributed in the plastids. However, few Ca2+ deposits were observed in the cytosol and nuclei. By spring of the next year (May), when plants were de-acclimated and resumed active growth, Ca2+ subcellular localization essentially restored to that observed in July of the last year, i.e., the cells contained low cytosolic and nuclear Ca2+ concentrations; Ca2+ deposits were mainly distributed in the vacuoles, cell walls and intercellular spaces. The relationships between the seasonal changes of intracellular Ca2+ concentration and the development of dormancy/cold acclimation, as well as plasmolysis associated with dormancy and cold hardiness were discussed.

  8. Endoplasmic Reticulum Ca(2+) Handling and Apoptotic Resistance in Tumor-Derived Endothelial Colony Forming Cells.

    Science.gov (United States)

    Poletto, Valentina; Dragoni, Silvia; Lim, Dmitry; Biggiogera, Marco; Aronica, Adele; Cinelli, Mariapia; De Luca, Antonio; Rosti, Vittorio; Porta, Camillo; Guerra, Germano; Moccia, Francesco

    2016-10-01

    Truly endothelial progenitor cells (EPCs) can be mobilized from bone marrow to support the vascular network of growing tumors, thereby sustaining the metastatic switch. Endothelial colony forming cells (ECFCs) are the only EPC subtype belonging to the endothelial phenotype and capable of incorporating within neovessels. The intracellular Ca(2+) machinery plays a key role in ECFC activation and is remodeled in renal cellular carcinoma-derived ECFCs (RCC-ECFCs). Particularly, RCC-ECFCs seems to undergo a drop in endoplasmic reticulum (ER) Ca(2+) concentration ([Ca(2+) ]ER ). This feature is remarkable when considering that inositol-1,4,5-trisphosphate (InsP3 )-dependent ER-to-mitochondria Ca(2+) transfer regulates the intrinsic apoptosis pathway. Herein, we sought to assess whether: (1) the [Ca(2+) ]ER and the InsP3 -induced ER-mitochondria Ca(2+) shuttle are reduced in RCC-ECFCs; and (2) the dysregulation of ER Ca(2+) handling leads to apoptosis resistance in tumor-derived cells. RCC-ECFCs displayed a reduction both in [Ca(2+) ]ER and in the InsP3 -dependent mitochondrial Ca(2+) uptake, while they expressed normal levels of Bcl-2 and Bak. The decrease in [Ca(2+) ]ER was associated to a remarkable ER expansion in RCC-ECFCs, which is a hallmark of ER stress, and did not depend on the remodeling of the Ca(2+) -transporting and the ER Ca(2+) -storing systems. As expected, RCC-ECFCs were less sensitive to rapamycin- and thapsigargin-induced apoptosis; however, buffering intracellular Ca(2+) levels with BAPTA dampened apoptosis in both cell types. Finally, store-operated Ca(2+) entry was seemingly uncoupled from the apoptotic machinery in RCC-ECFCs. Thus, the chronic underfilling of the ER Ca(2+) pool could confer a survival advantage to RCC-ECFCs and underpin RCC resistance to pharmacological treatment. J. Cell. Biochem. 117: 2260-2271, 2016. © 2016 Wiley Periodicals, Inc. PMID:26917354

  9. Modes of winter precipitation variability in the North Atlantic

    Energy Technology Data Exchange (ETDEWEB)

    Zorita, E. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Hydrophysik; Saenz, J.; Fernandez, J.; Zubillaga, J. [Bilbao Univ. (Spain)

    2001-07-01

    The modes of variability of winter precipitation in the North Atlantic sector are identified by Empirical Orthogonal Functions Analysis in the NCEP/NCAR global reanalysis data sets. These modes are also present in a gridded precipitation data set over the Western Europe. The large-scale fields of atmospheric seasonal mean circulation, baroclinic activity, evaporation and humidity transport that are connected to the rainfall modes have been also analyzed in order to investigate the physical mechanisms that are causally linked to the rainfall modes. The results indicate that the leading rainfall mode is associated to the North Atlantic oscillation and represents a meridional redistribution of precipitation in the North Atlantic through displacements of the storm tracks. The second mode is related to evaporation anomalies in the Eastern Atlantic that precipitate almost entirely in the Western Atlantic. The third mode seems to be associated to meridional transport of water vapor from the Tropical Atlantic. (orig.)

  10. Indian - Atlantic interocean exchange: variability and controls

    OpenAIRE

    Schouten, Mathijs Wilhelmus

    2003-01-01

    South of Africa, warm Indian Ocean water enters the Atlantic Ocean by means of large Agulhas Rings. These rings, with diameters up to 350 km and reaching all the way to the ocean floor at 5 km depth, form an important link in the global thermohaline circulation, which is the driving force behind the moderate temperatures over Northern Europe. For six years, the shedding of Agulhas rings has been monitored from space, using satellite altimeter measurements of the sea surface height. Rings can ...

  11. Fisheries. Population of origin of Atlantic cod.

    Science.gov (United States)

    Nielsen, E E; Hansen, M M; Schmidt, C; Meldrup, D; Grønkjaer, P

    2001-09-20

    Most of the world's cod (Gadus morhua) fisheries are now tightly regulated or closed altogether. Being able to link individual fish to their population of origin would assist enormously in policing regulations and in identifying poachers. Here we show that microsatellite genetic markers can be used to assign individual cod from three different populations in the northeastern Atlantic Ocean to their population of origin. PMID:11565021

  12. Residency, site fidelity and habitat use of Atlantic cod (Gadus morhua) at an offshore wind farm using acoustic telemetry.

    Science.gov (United States)

    Reubens, Jan T; Pasotti, Francesca; Degraer, Steven; Vincx, Magda

    2013-09-01

    Because offshore wind energy development is fast growing in Europe it is important to investigate the changes in the marine environment and how these may influence local biodiversity and ecosystem functioning. One of the species affected by these ecosystem changes is Atlantic cod (Gadus morhua), a heavily exploited, commercially important fish species. In this research we investigated the residency, site fidelity and habitat use of Atlantic cod on a temporal scale at windmill artificial reefs in the Belgian part of the North Sea. Acoustic telemetry was used and the Vemco VR2W position system was deployed to quantify the movement behaviour. In total, 22 Atlantic cod were tagged and monitored for up to one year. Many fish were present near the artificial reefs during summer and autumn, and demonstrated strong residency and high individual detection rates. When present within the study area, Atlantic cod also showed distinct habitat selectivity. We identified aggregation near the artificial hard substrates of the wind turbines. In addition, a clear seasonal pattern in presence was observed. The high number of fish present in summer and autumn alternated with a period of very low densities during the winter period. PMID:23937893

  13. Diagnostic value of joint detection of serum CA1 9-9,CA125 and CA242 for cholangiocarci-noma%血清 CA 19-9、CA 125、CA242联合检测对胆管癌诊断价值的评价

    Institute of Scientific and Technical Information of China (English)

    崔大鹏; 韩磊; 刘振显; 杨贺; 张迎春

    2016-01-01

    Objective:To study the diagnostic value of joint detection of serum CA1 9-9,CA125 and CA242 for cholan-giocarcinoma.Methods:A total of 35 patients with cholangiocarcinoma who received surgical resection in our hospital were se-lected as malignant group;30 patients with cholelithiasis who received surgical resection in our hospital during the same period were selected as benign group.Serum samples were collected before surgery to determine CA1 9-9,CA125 and CA242 content;and cholangiocarcinoma tissue and normal bile duct tissue were collected after surgery to determine the content of proliferation and invasion molecules.Results:Serum CA1 9-9,CA125 and CA242 levels of malignant group were significantly higher than those of control group (P <0.05);PROX-1,Ki-67,Bcl-2,Bad,Gab1,LOXL2,TRPM7 and CXCL12 levels in cholangiocar-cinoma tissue were significantly higher than those in benign bile duct tissue (P <0.05);and E-cadherin level was significantly lower than that in benign bile duct tissue (P <0.05);serum CA1 9-9,CA125 and CA242 levels were positively correlated with PROX-1,Ki-67,Bcl-2,Bad,Gab1,LOXL2,TRPM7 and CXCL12 levels,and negatively correlated with E-cadherin level. Conclusions:Joint detection of serum CA1 9-9,CA125 and CA242 can not only provide reference for the diagnosis of cholangio-carcinoma,but also can provide basis for the evaluation of proliferation,invasion and other malignant biological behaviors.%目的::研究血清 CA19-9、CA125、CA242联合检测对胆管癌的诊断价值.方法:选择在我院接受手术切除的35例胆管癌患者作为恶性组,同期在我院接受手术切除的30例胆石症患者作为良性组,术前采集血清标本并测定 CA19-9、CA125、CA242含量,术后采集胆管癌组织和正常胆管组织并测定增殖、侵袭分子的含量.结果:恶性组血清中 CA19-9、CA125、CA242的含量显著高于对照组(P <0.05);胆管癌组织中 PROX-1、Ki-67、Bcl-2、Bad、Gab1、LOXL2、TRPM7、CXCL12

  14. Local and remote impacts of a tropical Atlantic salinity anomaly

    OpenAIRE

    Mignot, Juliette; Frankignoul, Claude

    2009-01-01

    The climatic impacts of an enhanced evaporation prescribed during 50 years in the tropical Atlantic are investigated in a coupled ocean-atmosphere general circulation model. Locally, the salinity increase leads to a rapid deepening and cooling of the surface mixed layer. This induces a deepening of the equatorial undercurrent and an intensification of the south equatorial current. A remote atmospheric response to the tropical Atlantic perturbation is detected in the North Atlantic sector afte...

  15. Mechanisms and predictability of North Atlantic - European Climate

    OpenAIRE

    Pohlmann, H.

    2005-01-01

    This study investigates the mechanisms of North Atlantic-European climate using atmosphere general circulation models (AGCMs). Experiments with the AGCM ECHAM4, in which the sea surface temperature (SST) forcing is restricted to either the Atlantic or the Indo-Pacific oceans, show that both oceanic regions have an influence on North Atlantic-European climate in winter. In the experiment with SST forcing restricted to the Indo-Pacific oceans the atmospheric response projects on the North Atlan...

  16. Evidence of remote forcing in the Equatorial Atlantic ocean

    OpenAIRE

    Servain, J.; Picaut, Joël; Merle, Jacques

    1982-01-01

    An analysis of sea-surface temperature (STT) and surface winds in selected areas of the Tropical Atlantic indicates that the nonseasonal variability of SST in the Eastern Equatorial Atlantic (Gulf of Guinea) is highly correlated with the nonseasonal variability of the zonal wind stress in the Western Equatorial Atlantic. A negative (positive) anomaly of the zonal wind stress near the North Brazilian coast is followed by a positive (negative) SST anomaly in the Gulf of Guinea about one month l...

  17. NEFSC 2010 Atlantic Herring Acoustic/Midwater Trawl Survey (DE1010, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Atlantic herring acoustic survey is a fisheries independent survey that provides scientific data for Atlantic herring assessments in the U.S. mid-Atlantic...

  18. 75 FR 9158 - Atlantic Coastal Fisheries Cooperative Management Act Provisions; Coastal Sharks Fishery

    Science.gov (United States)

    2010-03-01

    ... National Oceanic and Atmospheric Administration RIN 0648-XU54 Atlantic Coastal Fisheries Cooperative Management Act Provisions; Coastal Sharks Fishery AGENCY: National Marine Fisheries Service (NMFS), National... provisions of the Atlantic Coastal Fisheries Cooperative Management Act (Atlantic Coastal Act). The...

  19. 75 FR 33242 - Atlantic Coastal Fisheries Cooperative Management Act Provisions; Weakfish Fishery

    Science.gov (United States)

    2010-06-11

    ... National Oceanic and Atmospheric Administration RIN 0648-XW45 Atlantic Coastal Fisheries Cooperative Management Act Provisions; Weakfish Fishery AGENCY: National Marine Fisheries Service (NMFS), National... the provisions of the Atlantic Coastal Fisheries Cooperative Management Act (Atlantic Coastal...

  20. NEFSC 1999 Atlantic Herring Acoustic/Midwater Trawl Survey (DE9909, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Atlantic herring acoustic survey is a fisheries independent survey that provides scientific data for Atlantic herring assessments in the U.S. mid-Atlantic...

  1. NEFSC 2008 Atlantic Herring Acoustic/Midwater Trawl Survey (DE0809, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Atlantic herring acoustic survey is a fisheries independent survey that provides scientific data for Atlantic herring assessments in the U.S. mid-Atlantic...

  2. NEFSC 2009 Atlantic Herring Acoustic/Midwater Trawl Survey (DE0910, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Atlantic herring acoustic survey is a fisheries independent survey that provides scientific data for Atlantic herring assessments in the U.S. mid-Atlantic...

  3. NEFSC 2011 Atlantic Herring Acoustic/Midwater Trawl Survey (DE1108, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Atlantic herring acoustic survey is a fisheries independent survey that provides scientific data for Atlantic herring assessments in the U.S. mid-Atlantic...

  4. NEFSC 2006 Atlantic Herring Acoustic/Midwater Trawl Survey (DE0615, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Atlantic herring acoustic survey is a fisheries independent survey that provides scientific data for Atlantic herring assessments in the U.S. mid-Atlantic...

  5. NEFSC 2012 Atlantic Herring Acoustic/Midwater Trawl Survey (PC1206, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Atlantic herring acoustic survey is a fisheries independent survey that provides scientific data for Atlantic herring assessments in the U.S. mid-Atlantic...

  6. NEFSC 2007 Atlantic Herring Acoustic/Midwater Trawl Survey (DE0710, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Atlantic herring acoustic survey is a fisheries independent survey that provides scientific data for Atlantic herring assessments in the U.S. mid-Atlantic...

  7. NEFSC 2004 Atlantic Herring Acoustic/Midwater Trawl Survey (DE0413, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Atlantic herring acoustic survey is a fisheries independent survey that provides scientific data for Atlantic herring assessments in the U.S. mid-Atlantic...

  8. NEFSC 1998 Atlantic Herring Acoustic/Midwater Trawl Survey (DE9810, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Atlantic herring acoustic survey is a fisheries independent survey that provides scientific data for Atlantic herring assessments in the U.S. mid-Atlantic...

  9. NEFSC 2002 Atlantic Herring Acoustic/Midwater Trawl Survey (DE0208, EK500)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NEFSC Atlantic herring acoustic survey is a fisheries independent survey that provides scientific data for Atlantic herring assessments in the U.S. mid-Atlantic...

  10. Investigation of periodic multilayers

    CERN Document Server

    Bodnarchuck, V; Ignatovich, V; Veres, T; Yaradaykin, S

    2009-01-01

    Periodic multilayers of various periods were prepared according to an algorithm proposed by the authors. The reflectivity properties of these systems were investigated using neutron reflectometry.The obtained experimental results were compared with the theoretical expectations. In first approximation, the results proved the main features of the theoretical predictions. These promising results initiate further research of such systems.

  11. The Living Periodic Table

    Science.gov (United States)

    Nahlik, Mary Schrodt

    2005-01-01

    To help make the abstract world of chemistry more concrete eighth-grade students, the author has them create a living periodic table that can be displayed in the classroom or hallway. This display includes information about the elements arranged in the traditional periodic table format, but also includes visual real-world representations of the…

  12. Historically defined autobiographical periods

    DEFF Research Database (Denmark)

    Brown, Norman R.; Hansen, Tia G. B.; Lee, Peter J.;

    2012-01-01

    The chapter reviews a research programme that has demonstrated the existence of historically defined autobiographical periods and identified the conditions that bring them about. Data from four samples of World War II-generation adults show that historically defined autobiographical periods endure...

  13. Diagenesis of lower Cretaceous pelagic carbonates, North Atlantic: Paleoceanographic signals obscured

    Science.gov (United States)

    Frank, T.D.; Arthur, M.A.; Dean, W.E.

    1999-01-01

    The stable isotope and minor element geochemistry of Neocomian (Lower Cretaceous) pelagic carbonates of the North Atlantic Basin (Deep Sea Drilling Project Sites 105, 367, 387, 391, and 603) was examined to develop a diagenetic model for pelagic limestones. In particular, we hoped to test the fidelity of whole-rock geochemical records as paleoceanographic indicators for pelagic deposits of pre-Aptian age, in which individual microfossils are not available for analysis. Data indicate that in addition to depth of burial, rhythmic variations in primary carbonate content have strongly controlled diagenetic patterns and associated geochemical signatures in these Neocomian sequences. Samples become increasingly depleted in Sr and 18O with increasing CaCO3 content. Within individual sedimentary sections, substantial decreases in Sr/Ca ratios and ??18O values are evident over a range of 4 to 98% CaCO3. However, even over a relatively narrow range of 50 to 98% CaCO3 a 2.5%c variation in ??18O values and a change of a factor of 1.7 in Sr/Ca ratios are observed. Carbon isotope compositions do not vary as extensively with CaCO3 content, but carbonate-rich intervals tend to be relatively depleted in 13C. Petrographic analysis reveals that these geochemical patterns are related to the transfer of CaCO3 from carbonate-poor intervals (calcareous shales and marlstones) to adjacent carbonate-rich intervals (limestones) during burial compaction and pressure solution. This process results in the addition of diagenetic cement to carbonate-rich intervals to produce a bulk composition that is relatively depleted in Sr and 18O and, at the same time, enables the retention of more-or-less primary carbonate that is relatively enriched in Sr and 18O in adjacent carbonate-poor intervals. Thus, although cyclic variations in CaCO3 content are primary in the Neocomian sequences examined, measured variations in Sr/Ca ratios and ??18O values are not and, as such, do not provide reliable proxies for

  14. Do West African thunderstorms predict the intensity of Atlantic hurricanes?

    Science.gov (United States)

    Price, Colin; Reicher, Naama; Yair, Yoav

    2015-04-01

    Since 85% of all major Atlantic hurricanes originate as thunderstorm clusters in equatorial Africa, we have investigated the connection between these African thunderstorms and the consequent development of these disturbances into tropical storms. We have analyzed Meteosat infrared cloud top temperature data to determine the areal coverage of cold cloud tops over a 6 year period from 2005 to 2010. In addition, hurricane statistics from the same period (intensity, date of generation, location, and maximum winds) were obtained from the National Hurricane Center database. We first show that the areal coverage of cold clouds (with brightness temperatures Tb tropical Africa is a good indicator of the monthly number of African Easterly Waves (AEWs) leaving the west coast of tropical Africa. Furthermore, the AEWs that develop into tropical storms have a significantly larger area covered by cold cloud tops compared with nondeveloping waves. Finally, we show that on a storm-by-storm basis, the cold cloud coverage in West Africa is positively correlated (r = 0.57) with the accumulated cyclone energy of the future tropical cyclones that develop out of these waves.

  15. Isotopic Effects on Stereodynamics for Ca+HCI, Ca+DCI, and Ca+TClReactions

    Institute of Scientific and Technical Information of China (English)

    Li-zhi Wang; Chuan-lu Yang; Jing-juan Liang; Jing Xiao; Qing-gang Zhang

    2011-01-01

    The vector correlations in Ca+HC1,Ca+DCI,and Ca+TCI reactions have been investigated by means of the quasi-classical trajectory calculations on PES constructed by means of multireference configuration interaction.The distributions of P(θr),P(Φr) and the PDDCSs of (2π/σ)(dσ00/dωt),(2π/σ)(dσ20/dωt),(2π/σ)(dσ22+/dωt),(2π/σ)(dσ21-/dωt) have been calculated based on the surface.The remarkable isotopic effects in the reactions are observed,and the mechanism which may be ascribed to different mass factors is discussed.

  16. Levels of CaV1.2 L-Type Ca2+ Channels Peak in the First Two Weeks in Rat Hippocampus Whereas CaV1.3 Channels Steadily Increase through Development

    Directory of Open Access Journals (Sweden)

    Audra A. Kramer

    2012-01-01

    Full Text Available Influx of calcium through voltage-dependent channels regulates processes throughout the nervous system. Specifically, influx through L-type channels plays a variety of roles in early neuronal development and is commonly modulated by G-protein-coupled receptors such as GABAB receptors. Of the four isoforms of L-type channels, only CaV1.2 and CaV1.3 are predominately expressed in the nervous system. Both isoforms are inhibited by the same pharmacological agents, so it has been difficult to determine the role of specific isoforms in physiological processes. In the present study, Western blot analysis and confocal microscopy were utilized to study developmental expression levels and patterns of CaV1.2 and CaV1.3 in the CA1 region of rat hippocampus. Steady-state expression of CaV1.2 predominated during the early neonatal period decreasing by day 12. Steady-state expression of CaV1.3 was low at birth and gradually rose to adult levels by postnatal day 15. In immunohistochemical studies, antibodies against CaV1.2 and CaV1.3 demonstrated the highest intensity of labeling in the proximal dendrites at all ages studied (P1–72. Immunohistochemical studies on one-week-old hippocampi demonstrated significantly more colocalization of GABAB receptors with CaV1.2 than with CaV1.3, suggesting that modulation of L-type calcium current in early development is mediated through CaV1.2 channels.

  17. CARINA oxygen data in the Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    I. Stendardo

    2009-12-01

    Full Text Available In the CARINA (Carbon dioxide in the Atlantic Ocean project, a new dataset with many previously unpublished hydrographic data from the Atlantic, Arctic and Southern Ocean was assembled and subjected to careful quality control (QC procedures. Here, we present the dissolved oxygen measurements in the Atlantic region of the dataset and describe in detail the secondary QC procedures that aim to ensure that the data are internally consistent. This is achieved by a cross-over analysis, i.e. the comparison of deep ocean data at places that were sampled by different cruises at different times. Initial adjustments to the individual cruises were then determined by an inverse procedure that computes a set of adjustments that requires the minimum amount of adjustment and at the same time reduces the offsets in an optimal manner. The initial adjustments were then reviewed by the CARINA members, and only those that passed the following two criteria were adopted: (i the region is not subject to substantial temporal variability, and (ii the adjustment must be based on at least three stations from each cruise. No adjustment was recommended for cruises that did not fit these criteria. The final CARINA-Oxygen dataset has 103414 oxygen samples from 9491 stations obtained during 98 cruises covering three decades. The sampling density of the oxygen data is particularly good in the North Atlantic north of about 40° N especially after 1987. In contrast, the sample density in the South Atlantic is much lower. Some cruises appear to have poor data quality, and were subsequently omitted from the adjusted dataset. Of the data included in the adjusted dataset, 20% were adjusted with a mean adjustment of 2%. Due to the achieved internal consistency, the resulting product is well suited to produce an improved climatology or to study long-term changes in the oxygen content of the ocean. However, the adjusted dataset is not necessarily better suited than the unadjusted data to

  18. Late Holocene intermediate water variability in the northeastern Atlantic as recorded by deep-sea corals

    Science.gov (United States)

    Copard, K.; Colin, C.; Henderson, G. M.; Scholten, J.; Douville, E.; Sicre, M.-A.; Frank, N.

    2012-01-01

    The Nd isotopic composition of the aragonite skeleton of fossil deep-sea corals ( Lophelia pertusa, Madrepora oculata and Desmophyllum dianthus) located in the northeastern Atlantic at water depths between 635 and 1300 m was investigated to reconstruct changes in the Atlantic mid-depth gyre circulation during the past millennium. The coral ɛNd values varied systematically from - 11.8 to - 14.4 during the past 1500 years, reflecting variations in seawater ɛNd and thus water mass provenance. Low ɛNd values (ɛNd = - 14) occurred during the warm Medieval Climatic Anomaly (MCA) (between 1000 AD and 1250 AD) and during the most recent period (1950 AD to 2000 AD), interrupted by a period of significantly higher ɛNd values (~-12.5) during the Little Ice Age (LIA) (between 1350 AD and 1850 AD). One long-lived branching coral even recorded an abrupt systematic rise from low to high ɛNd values around 1250 AD over the course of its 10-year growth period. These variations are interpreted to result from variable contributions of the subpolar and subtropical Atlantic intermediate water masses, which today are characterized by ɛNd values of - 15 and ~-11, respectively. The low ɛNd values observed during the warm MCA and during recent times imply a strong eastward extension of the mid-depth subpolar gyre (SPG) induced by a dominant positive phase of the North Atlantic oscillation (NAO). During the LIA, water from the subtropical gyre (STG) and potentially from the Mediterranean Sea Water (MSW) propagated further northward, as indicated by the higher coral ɛNd values. This pattern suggests a negative mean state of the NAO during the LIA, with weaker and more southerly located Westerlies and a westward contraction of the SPG. Variations in the contributions of the two gyres imply changes in the heat and salt budgets at intermediate depths during the past millennia that may have contributed to changes in the properties of North Atlantic inflow into the Nordic Seas and thus

  19. Probabilistic tsunami hazard in the North East Atlantic due to seismic sources, implications for NEAMTWS

    Science.gov (United States)

    Omira, R.; Baptista, M.; Matias, L. M.; Miranda, J. M.; Carrilho, F.

    2013-12-01

    Recently, several studies on tsunami hazard assessment for the North East Atlantic coasts have been published. These studies use deterministic approach based upon the most credible earthquake scenario and/or the worst case scenario to derive tsunami coastal hazard in terms of wave elevation and inundation maps. In this work, we present the first thorough study on probabilistic tsunami hazard assessment due to earthquake sources for the North East Atlantic area. We consider three main seismogenic areas: the Gulf of Cadiz, the Gloria Fault and the Caribbean arc. For each seismogenic zone we derive the annual recurrence rate for each magnitude range, starting from Mw7.5 to Mw9.0, using the Bayesian method that incorporates seismic information from historical catalog and instrumental periods. A numerical code, solving the linear shallow water equations is employed to simulate the tsunami propagation and compute near shore wave heights along the entire NE Atlantic coast and at the forecast points of the NEAMTWS. To establish, for multiple sources, the joint probability that wave height exceeds a particular value for a given time period, we consider that the sources are independent (like in the Poison distribution). This process allows calculating the time-independent probability that wave height, simulated by numerical code, will be exceeded due to the occurrence of a tsunami source with a known average rate, derived from sources' recurrence assessment, during a period of time. The results are presented in terms of the probability of exceedance of a given tsunami amplitude for 100, 500 and 1000 years, and hazard curves for selected forecast points of the NEAMTWS countries. The level of hazard varies along the coast being maximum along the northern segment of the Morocco Atlantic coast, the southern Portuguese coast and the Spanish coast of the Gulf of Cadiz. The results show that the probability of a tsunami wave exceeding 1 m in the next 500 years reaches 100% in some

  20. EMRE Is a Matrix Ca(2+) Sensor that Governs Gatekeeping of the Mitochondrial Ca(2+) Uniporter.

    Science.gov (United States)

    Vais, Horia; Mallilankaraman, Karthik; Mak, Don-On Daniel; Hoff, Henry; Payne, Riley; Tanis, Jessica E; Foskett, J Kevin

    2016-01-26

    The mitochondrial uniporter (MCU) is an ion channel that mediates Ca(2+) uptake into the matrix to regulate metabolism, cell death, and cytoplasmic Ca(2+) signaling. Matrix Ca(2+) concentration is similar to that in cytoplasm, despite an enormous driving force for entry, but the mechanisms that prevent mitochondrial Ca(2+) overload are unclear. Here, we show that MCU channel activity is governed by matrix Ca(2+) concentration through EMRE. Deletion or charge neutralization of its matrix-localized acidic C terminus abolishes matrix Ca(2+) inhibition of MCU Ca(2+) currents, resulting in MCU channel activation, enhanced mitochondrial Ca(2+) uptake, and constitutively elevated matrix Ca(2+) concentration. EMRE-dependent regulation of MCU channel activity requires intermembrane space-localized MICU1, MICU2, and cytoplasmic Ca(2+). Thus, mitochondria are protected from Ca(2+) depletion and Ca(2+) overload by a unique molecular complex that involves Ca(2+) sensors on both sides of the inner mitochondrial membrane, coupled through EMRE.

  1. Do the recent severe droughts in the Amazonia have the same period of length?

    CERN Document Server

    Zou, Yong; Sampaio, Gilvan; Mário, Antônio; Kurths, Jürgen

    2015-01-01

    We propose a new measure based on drought period length to assess the temporal difference between the recent two severe droughts of 2005 and 2010 in the Amazonia. The sensitivity of the measure is demonstrated by disclosing the distinct spatial responding mechanisms of the Northeastern and Southwestern Amazon (NA, SA) to the surrounding sea surface temperature (SST) variabilities. The Pacific and Atlantic oceans have different roles on the precipitation patterns in Amazonia. More specifically, the very dry periods in the NA are influenced by El Ni\\~no events, while the very dry periods in the SA are affected by the anomalously warming of the SST in the North Atlantic. We show convincingly that the drought 2005 hit SA, which is caused by the North Atlantic only. There are two phases in the drought 2010: (i) it was started in the NA in August 2009 affected by the El Ni\\~no event, and (ii) later shifted the center of action to SA resulted from anomalously high SST in North Atlantic, which further intensifies the...

  2. Evidence for cooler European summers during periods of changing meltwater flux to the North Atlantic

    OpenAIRE

    Heiri, O.; Tinner, W.; A. F. Lotter

    2004-01-01

    We analyzed fossil chironomids (nonbiting midges) and pollen in two lake-sediment records to reconstruct and quantify Holocene summer-temperature fluctuations in the European Alps. Chironomid and pollen records indicate five centennial-scale cooling episodes during the early- and mid-Holocene. The strongest temperature declines of ≈1°C are inferred at ≈10,700–10,500 and 8,200–7,600 calibrated 14C years B.P., whereas other temperature fluctuations are of smaller amplitude. Two forcing mechanis...

  3. A Possible Feedback Mechanism Involving the Arctic Freshwater,the Arctic Sea Ice, and the North Atlantic Drift

    Institute of Scientific and Technical Information of China (English)

    Odd Helge OTTER(A); Helge DRANGE

    2004-01-01

    Model studies point to enhanced warming and to increased freshwater fluxes to high northern latitudes in response to global warming. In order to address possible feedbacks in the ice-ocean system in response to such changes, the combined effect of increased freshwater input to the Arctic Ocean and Arctic warming--the latter manifested as a gradual melting of the Arctic sea ice--is examined using a 3-D isopycnic coordinate ocean general circulation model. A suite of three idealized experiments is carried out: one control integration, one integration with a doubling of the modern Arctic river runoff, and a third more extreme case, where the river runoff is five times the modern value. In the two freshwater cases, the sea ice thickness is reduced by 1.5-2 m in the central Arctic Ocean over a 50-year period. The modelled ocean response is qualitatively the same for both perturbation experiments: freshwater propagates into the Atlantic Ocean and the Nordic Seas, leading to an initial weakening of the North Atlantic Drift.Furthermore, changes in the geostrophic currents in the central Arctic and melting of the Arctic sea ice lead to an intensified Beaufort Gyre, which in turn increases the southward volume transport through the Canadian Archipelago. To compensate for this southward transport of mass, more warm and saline Atlantic water is carried northward with the North Atlantic Drift. It is found that the increased transport of salt into the northern North Atlantic and the Nordic Seas tends to counteract the impact of the increased freshwater originating from the Arctic, leading to a stabilization of the North Atlantic Drift.

  4. A high resolution salinity time series 1993-2012 in the North Atlantic from Argo and Altimeter data

    Science.gov (United States)

    Stendardo, I.; Rhein, M.; Hollmann, R.

    2016-04-01

    The study of salinity changes has been hampered by the lack of temporal and spatial resolution of the observations. In order to improve the spatial and temporal distribution of salinity observations, we used the Gravest Empirical Mode (GEM) technique to calculate high-resolution salinity distributions as a function of dynamic height for the period 1993-2012. This technique combined Argo and altimeter data to exploit the relationship between T/S profiles and dynamic height in the North Atlantic. The method was valid in the upper 700 m mainly at and near the pathways of the North Atlantic Current (NAC), but failed in regions with weak stratification or with ambiguities in the T/S relationships. Coherent, multiannual large-scale variability was observed, with many features present in all regions, albeit with weaker amplitudes in the eastern basins. Some of the interannual features in the northeastern Atlantic basins were unrelated to the variability further south and west, pointing to an occasional advection of subtropical water in the eastern Atlantic. Origin and advection of salinity anomalies with the NAC from the North American Basin into the western subpolar North Atlantic are correlated with the state of the North Atlantic Oscillation (NAO) and dampened by the surface freshwater fluxes. Other mechanisms influencing the salinity pattern are the changing location of the subpolar front, also related to the NAO. The large multiyear variability in the 20 year time series obscured any potential trends caused by global warming. Only the Rockall Trough showed a salinity increase of 0.03 per decade.

  5. Pairwise comparisons to reconstruct mean temperature in the Arctic Atlantic Region over the last 2,000 years

    Science.gov (United States)

    Hanhijärvi, Sami; Tingley, Martin P.; Korhola, Atte

    2013-10-01

    Existing multi-proxy climate reconstruction methods assume the suitably transformed proxy time series are linearly related to the target climate variable, which is likely a simplifying assumption for many proxy records. Furthermore, with a single exception, these methods face problems with varying temporal resolutions of the proxy data. Here we introduce a new reconstruction method that uses the ordering of all pairs of proxy observations within each record to arrive at a consensus time series that best agrees with all proxy records. The resulting unitless composite time series is subsequently calibrated to the instrumental record to provide an estimate of past climate. By considering only pairwise comparisons, this method, which we call PaiCo, facilitates the inclusion of records with differing temporal resolutions, and relaxes the assumption of linearity to the more general assumption of a monotonically increasing relationship between each proxy series and the target climate variable. We apply PaiCo to a newly assembled collection of high-quality proxy data to reconstruct the mean temperature of the Northernmost Atlantic region, which we call Arctic Atlantic, over the last 2,000 years. The Arctic Atlantic is a dynamically important region known to feature substantial temperature variability over recent millennia, and PaiCo allows for a more thorough investigation of the Arctic Atlantic regional climate as we include a diverse array of terrestrial and marine proxies with annual to multidecadal temporal resolutions. Comparisons of the PaiCo reconstruction to recent reconstructions covering larger areas indicate greater climatic variability in the Arctic Atlantic than for the Arctic as a whole. The Arctic Atlantic reconstruction features temperatures during the Roman Warm Period and Medieval Climate Anomaly that are comparable or even warmer than those of the twentieth century, and coldest temperatures in the middle of the nineteenth century, just prior to the onset

  6. Freshwater Variability in the Arctic Ocean and Subpolar North Atlantic: a Comparison from the 1990s to Present

    Science.gov (United States)

    Horn, Myriel; Rabe, Benjamin; Schauer, Ursula

    2016-04-01

    A significant increase in liquid freshwater content has been observed in the Arctic Ocean over the last 20 years, whereas the Arctic sea ice volume shrank significantly. In contrast, the North Atlantic became more saline in recent years. Both regions are of great importance for the global ocean circulation and climate, and salinity changes may have a profound impact on the global climate. We found that for the period between 1992 and 2013, the liquid freshwater content of the subpolar North Atlantic, calculated from objectively mapped in-situ salinity measurements, and the total freshwater content of the Arctic Ocean, i.e. the liquid freshwater content and freshwater stored in sea ice, are significantly negative correlated (r=-0.77). Moreover, the amount of the anomalies are of the same size. Furthermore, the time series hint at multi-decadal oscillations. The highest negative correlation with the total freshwater content of the Arctic Ocean can be found in the Irminger and Labrador Seas, while we observed a positive correlation east of the Mid-Atlantic Ridge at the path of the North Atlantic Current, which is the source of Atlantic Water entering the Arctic Ocean through the Nordic Seas. We suggest a redistribution of freshwater as a response to frequent changes in atmospheric pressure patterns. Under certain conditions the freshwater is re-routed and kept in the Arctic Ocean, while it is released under other conditions. We conclude that decadal scale changes of the freshwater content in the North Atlantic, particularly those in the deep water formation sites like the Labrador Sea, are originating in the Arctic Ocean.

  7. Mean-periodic functions

    Directory of Open Access Journals (Sweden)

    Carlos A. Berenstein

    1980-01-01

    Full Text Available We show that any mean-periodic function f can be represented in terms of exponential-polynomial solutions of the same convolution equation f satisfies, i.e., u∗f=0(μ∈E′(ℝn. This extends to n-variables the work of L. Schwartz on mean-periodicity and also extends L. Ehrenpreis' work on partial differential equations with constant coefficients to arbitrary convolutors. We also answer a number of open questions about mean-periodic functions of one variable. The basic ingredient is our work on interpolation by entire functions in one and several complex variables.

  8. Jehovah's Witnesses' three periods

    Directory of Open Access Journals (Sweden)

    Åke V. Ström

    1975-01-01

    Full Text Available Among modern formations of religion, arisen within Christendom, there is no one that has changed its doctrine and attitude so much as Jehovah's Witnesses, so that the religious content in the three periods can be labelled as new, newer, the newest. Each period is connected with and dependent upon the three presidents Charles Taze Russel, born in 1852, president 1881-1916, Joseph Franklin Rutherford, born in 1869, president 1916-1942, and Nathan Homer Knorr, born in 1905, president from 1942. The purpose here is to clarify some important differences between the three periods.

  9. On some periodicity effects

    DEFF Research Database (Denmark)

    Sorokin, Sergey V.

    2015-01-01

    . In each case, special attention is paid to eigenfrequencies and eigenmodes of a single periodicity cell with appropriate boundary conditions. The influence of the amount of periodicity cells in a finite compound structure on its eigenfrequency spectrum is analyzed. Several features common...... for the considered models are found and discussed in the context of the existing knowledge on the subject. Another issue addressed in the lecture is an influence of the corrugation shape and amplitude on the broadness and location of the stop- and pass-bands in an infinite periodic structure. Explicit asymptotic...

  10. Distribution and abundance of fin whales (Balaenoptera physalus in the Northeast and Central Atlantic as inferred from the North Atlantic Sightings Surveys 1987-2001

    Directory of Open Access Journals (Sweden)

    Gísli A Víkingsson

    2013-10-01

    Full Text Available North Atlantic Sightings Surveys (NASS is a series of large scale international cetacean line transect surveys, conducted in 1987, 1989, 1995 and 2001, that covered a large part of the central and eastern North Atlantic. Target species were fin (Balaenoptera physalus, common minke (B. acutorostrata, pilot (Globicephala melas and sei (B. borealis whales. Here we present new estimates of abundance for fin whales from the 2 most recent surveys and analysis of trends throughout the survey period. Fin whales were found in highest densities in the Irminger Sea between Iceland and Greenland. Abundance of fin whales in the survey area of the Icelandic and Faroese vessels (Central North Atlantic was estimated as 19,672 (95% C.I. 12,083-28,986 animals in 1995 and 24,887 (95% C.I. 18,186-30,214 in 2001. The estimates are negatively biased because of whales diving during the passage of vessels, and whales being missed by observers, but these and other potential biases are likely small for this species. The abundance of fin whales increased significantly over the survey period. For all areas combined the estimated annual growth rate was 4%. An estimated annual increase of 10% in the area between Iceland and Greenland was responsible for most of this overall increase in numbers of fin whales in the area. Although high, the estimated rates of increase are not out of bounds of biological plausibility and can thus be viewed as recovery of a depleted population. However, the apparent pattern of population growth and the whaling history in the area indicate that fin whales made a significant recovery during the first half of the 20th century and that the recent observed high growth rates cannot be explained solely by recovery after overexploitation. 

  11. Metabolism of intra muscularly injected 45Ca in a buffalo (Babalus bubalis) during late lactation

    International Nuclear Information System (INIS)

    Intramuscular injection of 45CaCl2 in to a buffalo during late lactation suggested an immediate transport of the injected 45Ca into blood followed by its secretion or excretion into milk, urine and faeces. Calcium from blood is concentrated several folds by mammary secretory cells before secretion. Over a period of 162 hr after administration of 45Ca, the cumulative activity of 45Ca (per cent of injected dose) secreted or excreted in the milk, urine and faeces was 11.75, 4.26 and 52.07 per cent, respectively. Subsequently secretion of 45Ca (per cent of injected dose) into milk decreased to 0.22 per cent at 1001 to 1200 hr after administration of 45CaCl2. (author). 10 refs., 3 figs., 1 tab

  12. Periodicities of hail precipitation in France

    Science.gov (United States)

    Hermida, Lucía; Sánchez, José Luis; Berthet, Claude; Dessens, Jean; López, Laura; Hierro, Rodrigo; Wu, Xueke; García-Ortega, Eduardo

    2013-04-01

    The wavelet analysis is a powerful tool appropriated for studying multiscale and non-stationary processes that occur in finite spatial and temporal domains. Its development began with Morlet and, since then, the wavelet transform (WT) has had better applications in Geophysics. However, the characterization of hail precipitation is not exempt from difficulty, since it deals with phenomenon on a small scale, with elevated spatial and temporal variation. The extreme variability of the frequency and distribution of hail is attributed, among other things, to the same process of its formation. The conditions that influence hail formation span from air masses climatology to lower-scale factors such as orography, wind fields, concentration of ice nuclei or temperature. This last factor is important both from a point of view of convective activity as well as its influence in the height of the freezing point. Thus, it would be possible to do comparative analysis between time series of temperature and diverse hail variables; or, rather, to try to establish a relationship between periodicities found and phenomenon such as ENSO (El Niño, Southern Oscillation) or NAO (North-Atlantic Oscillation). France is one of the European countries that is most affected by hail precipitation. Previous climatic studies have been done with the objective of characterizing the long-term variability of distinct variables of this hydrometeor that is present in the time series. These measurements are obtained using networks of hailpads distributed in French territory and managed by ANELFA. Berthet et al. (2011) observed the annual hail frequency in France, finding successions of three years with high values followed by three years of low values; this being calculated as the number of hailfalls per year divided by the number of hailpad stations that were in use during said year. In the present paper, a wavelet analysis was carried out with the objective of detecting the possible existence of

  13. Effects of hexazinone and atrazine on the physiology and endocrinology of smolt development in Atlantic salmon

    Science.gov (United States)

    Nieves-Puigdoller, K.; Bjornsson, Bjorn Thrandur; McCormick, S.D.

    2007-01-01

    Exposure to hexazinone (HEX) and atrazine (ATZ), highly mobile and widely used herbicides along rivers in the United States, is potentially harmful to Atlantic salmon, which have been listed as an endangered species. To determine the effects of these contaminants on smolt development, juvenile Atlantic salmon were exposed under flow-through conditions to 100 ??g l-1 HEX, 10 and 100 ??g l-1 ATZ in fresh water (FW) for 21 days at 10 ??C beginning in mid-April. Twelve fish per treatment were sampled in FW, following a 24 h seawater (SW) challenge and after growth for 3 months in SW. Exposure to 100 ??g l-1 HEX or 10 ??g l-1 ATZ caused no mortalities of smolts in FW or after SW challenge, while 9% of the fish exposed to 100 ??g l-1 ATZ died during exposure. Fish exposed to 100 ??g l-1 ATZ reduced feeding after 10 days of exposure and had an impaired growth rate in FW and during the first month in SW; compensatory growth occurred in the second and third month in SW. HEX and ATZ at 10 ??g l-1 exposure had no effect on plasma levels of cortisol, growth hormone (GH), insulin growth factor I (IGF-I), thyroxine (T4) and plasma 3,5,3???-triiodo-l-thyronine (T3), Cl-, Mg2+, Na+, Ca2+ in FW or after SW challenge. FW smolts exposed to 100 ??g l-1 ATZ had decreased plasma Cl-, Mg2+, Na+ and Ca2+ ions and increased cortisol. No effect on plasma levels of GH, IGF-I, T4 or T3 was found in FW smolts exposed to 100 ??g l-1 ATZ. Following SW challenge, fish previously exposed to 100 ??g l-1 ATZ had significant increases in hematocrit, plasma cortisol, Cl-, Mg2+, Na+, Ca2+ and a decrease in T4 and T3. It is concluded that under the conditions imposed in this study, HEX does not affect salinity tolerance of Atlantic salmon smolts, while ATZ causes ionoregulatory, growth and endocrine disturbance. ?? 2007 Elsevier B.V. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    D. Handiani

    2012-07-01

    Full Text Available The Bølling-Allerød (BA, starting ~ 14.5 ka BP is one of the most pronounced abrupt warming periods recorded in ice and pollen proxies. The leading explanation of the cause of this warming is a sudden increase in the rate of deepwater formation in the North Atlantic Ocean and the resulting effect on the heat transport by the Atlantic Meridional Overturning Circulation (AMOC. In this study, we used the University of Victoria (UVic Earth System-Climate Model (ESCM to run simulations, in which a freshwater perturbation initiated a BA-like warming period. We found that under present climate conditions, the AMOC intensified when freshwater was added to the Southern Ocean. However, under Heinrich event 1 (HE1, ~ 16 ka BP climate conditions, the AMOC only intensified when freshwater was extracted from the North Atlantic Ocean, possibly corresponding to an increase in evaporation or a decrease in precipitation in this region. The intensified AMOC led to a warming in the North Atlantic Ocean and a cooling in the South Atlantic Ocean, resembling the bipolar seesaw pattern typical of the last glacial period.

    In addition to the physical response, we also studied the simulated vegetation response around the Atlantic Ocean region. Corresponding with the bipolar seesaw hypothesis, the rainbelt associated with the Intertropical Convergence Zone (ITCZ shifted northward and affected the vegetation pattern in the tropics. The most sensitive vegetation area was found in tropical Africa, where grass cover increased and tree cover decreased under dry climate conditions. An equal but opposite response to the collapse and recovery of the AMOC implied that the change in vegetation cover was transient and robust to an abrupt climate change such as during the BA period, which is also supported by paleovegetation data. The results are in agreement with paleovegetation records from Western tropical Africa, which also show a reduction in forest cover during this

  15. Setting the Periodic Table.

    Science.gov (United States)

    Saturnelli, Annette

    1985-01-01

    Examines problems resulting from different forms of the periodic table, indicating that New York State schools use a form reflecting the International Union of Pure and Applied Chemistry's 1984 recommendations. Other formats used and reasons for standardization are discussed. (DH)

  16. The Periodic Table CD.

    Science.gov (United States)

    Banks, Alton J.; Holmes, Jon L.

    1995-01-01

    Describes the characteristics of the digitized version of The Periodic Table Videodisc. Provides details about the organization of information and access to the data via Macintosh and Windows computers. (DDR)

  17. Painful periods (dysmenorrhea) (image)

    Science.gov (United States)

    Primary dysmenorrhea is a normal cramping of the lower abdomen caused by hormone-induced uterine contractions before the period. Secondary dysmenorrhea may be caused by abnormal conditions such as ...

  18. Optimal periodic control

    CERN Document Server

    Colonius, Fritz

    1988-01-01

    This research monograph deals with optimal periodic control problems for systems governed by ordinary and functional differential equations of retarded type. Particular attention is given to the problem of local properness, i.e. whether system performance can be improved by introducing periodic motions. Using either Ekeland's Variational Principle or optimization theory in Banach spaces, necessary optimality conditions are proved. In particular, complete proofs of second-order conditions are included and the result is used for various versions of the optimal periodic control problem. Furthermore a scenario for local properness (related to Hopf bifurcation) is drawn up, giving hints as to where to look for optimal periodic solutions. The book provides mathematically rigorous proofs for results which are potentially of importance in chemical engineering and aerospace engineering.

  19. Establishing contract periods

    International Nuclear Information System (INIS)

    The lead time for executing the Adjustable Fixed-Commitment (AFC) contract and exceptions which may be considered are discussed. The initial delivery period is also discussed. Delays, deferrals, and schedule adjustment charges are finally considered

  20. Microevolution in time and space: SNP analysis of historical DNA reveals dynamic signatures of selection in Atlantic cod

    DEFF Research Database (Denmark)

    Therkildsen, Nina Overgaard; Hansen, Jakob Hemmer; Als, Thomas Damm;

    2013-01-01

    of Atlantic cod (Gadus morhua) studied over an 80-year period. Screening of >1000 gene-associated single-nucleotide polymorphisms (SNPs) identified 77 loci that showed highly elevated levels of differentiation, likely as an effect of directional selection, in either time, space or both. Exploratory analysis...... the 1928 to 1960 period showed almost complete stability during later decades. The contrasting microevolutionary trajectories among populations resulted in sequential shifts in spatial outliers, with no locus maintaining elevated spatial differentiation throughout the study period. Simulations of migration...

  1. Regulation by L channels of Ca(2+)-evoked secretory responses in ouabain-treated chromaffin cells.

    Science.gov (United States)

    De Pascual, Ricardo; Colmena, Inés; Ruiz-Pascual, Lucía; Baraibar, Andrés Mateo; Egea, Javier; Gandía, Luis; García, Antonio G

    2016-10-01

    It is known that the sustained depolarisation of adrenal medullary bovine chromaffin cells (BCCs) with high K(+) concentrations produces an initial sharp catecholamine release that subsequently fades off in spite depolarisation persists. Here, we have recreated a sustained depolarisation condition of BCCs by treating them with the Na(+)/K(+) ATPase blocker ouabain; in doing so, we searched experimental conditions that permitted the development of a sustained long-term catecholamine release response that could be relevant during prolonged stress. BCCs were perifused with nominal 0Ca(2+) solution, and secretion responses were elicited by intermittent application of short 2Ca(2+) pulses (Krebs-HEPES containing 2 mM Ca(2+)). These pulses elicited a biphasic secretory pattern with an initial 30-min period with secretory responses of increasing amplitude and a second 30-min period with steady-state, non-inactivating responses. The initial phase was not due to gradual depolarisation neither to gradual increases of the cytosolic calcium transients ([Ca(2+)]c) elicited by 2Ca(2+) pulses in BBCs exposed to ouabain; both parameters increased soon after ouabain addition. Νifedipine blocked these responses, and FPL64176 potentiated them, suggesting that they were triggered by Ca(2+) entry through non-inactivating L-type calcium channels. This was corroborated by nifedipine-evoked blockade of the L-type Ca(2+) channel current and the [Ca(2+)]c transients elicited by 2Ca(2+) pulses. Furthermore, the plasmalemmal Na(+)/Ca(2+) exchanger (NCX) blocker SEA0400 caused a mild inhibition followed by a large rebound increase of the steady-state secretory responses. We conclude that these two phases of secretion are mostly contributed by Ca(2+) entry through L calcium channels, with a minor contribution of Ca(2+) entry through the reverse mode of the NCX.

  2. Influence of the Atlantic Multidecadal Oscillation on the Winter Climate of East China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The Atlantic Multidecadal Oscillation (AMO), the multidecadal variation of North Atlantic sea surface temperature (SST), exhibits an oscillation with a period of 65-80 years and an amplitude of 0.4°C. Observational composite analyses reveal that the warm phase AMO is linked to warmer winters in East China, with enhanced precipitation in the north of this region and reduced precipitation in the south, on multidecaclal time scales. The pattern is reversed during the cold phase AMO. Whether the AMO acts as a forcing of the multidecadal winter climate of East China is explored by investigating the atmospheric response to warm AMO SST anomalies in a large ensemble of atmospheric general circulation model (AGCM) experiments.The results from three AGCMs are consistent and suggest that the AMO warmth favors warmer winters in East China. This influence is realized through inducing negative surface air pressure anomalies in the hemispheric-wide domain extending from the midlatitude North Atlantic to midlatitude Eurasia. These negative surface anomalies favor the weakening of the Mongolian Cold High, and thus induce a weaker East Asian Winter Monsoon.

  3. Uniform climate development between the subtropical and subpolar Northeast Atlantic across marine isotope stage 11

    Directory of Open Access Journals (Sweden)

    J. P. Helmke

    2008-04-01

    Full Text Available Proxy records from a core site off Northwest Africa were generated and compared with data from the subpolar Northeast Atlantic to unravel some main climatic features of interglacial marine isotope stage (MIS 11 (423–362 ka. The records point to an almost 25 kyr lasting full interglacial period during stage 11 that was preceded by a considerably long glacial-interglacial transition (Termination V. Off NW Africa, a strong reduction of terrestrially derived iron input is noted after 420 ka suggesting a pronounced increase in continental humidity and vegetation cover over Northwest Africa. In analogy to the Holocene climate of the region, this early wet phase of MIS 11 was likely associated with enhanced influence of the West African monsoon system on the Saharan-Sahel region which led to both a reduction in trade wind intensity off NW Africa and the formation of sapropel S11 in the Mediterranean Sea. A detailed comparison with data from the subpolar North Atlantic indicates a remarkable coherent timing for the main environmental changes in both regions giving evidence for strong interglacial climate connectivity between the low and high latitude North Atlantic. Although our records of MIS 11 compare well with the Holocene in terms of some major climate characteristics there are distinct differences in the temporal evolution of each peak warm interval. This suggests that care should be taken when using MIS 11 as analogue to forecast future interglacial conditions.

  4. Variability of the North Atlantic summer storm track: mechanisms and impacts on European climate

    International Nuclear Information System (INIS)

    The summertime variability of the extratropical storm track over the Atlantic sector and its links to European climate have been analysed for the period 1948–2011 using observations and reanalyses. The main results are as follows. (1) The dominant mode of the summer storm track density variability is characterized by a meridional shift of the storm track between two distinct paths and is related to a bimodal distribution in the climatology for this region. It is also closely related to the Summer North Atlantic Oscillation (SNAO). (2) A southward shift is associated with a downstream extension of the storm track and a decrease in blocking frequency over the UK and northwestern Europe. (3) The southward shift is associated with enhanced precipitation over the UK and northwestern Europe and decreased precipitation over southern Europe (contrary to the behaviour in winter). (4) There are strong ocean–atmosphere interactions related to the dominant mode of storm track variability. The atmosphere forces the ocean through anomalous surface fluxes and Ekman currents, but there is also some evidence consistent with an ocean influence on the atmosphere, and that coupled ocean–atmosphere feedbacks might play a role. The ocean influence on the atmosphere may be particularly important on decadal timescales, related to the Atlantic Multidecadal Oscillation (AMO). (letter)

  5. The mechanism of multidecadal variability in the Arctic and North Atlantic in climate model INMCM4

    International Nuclear Information System (INIS)

    Data from a 500-year preindustrial control run of climate model INMCM4 show distinct climate variability in the Arctic and North Atlantic with a period of 35–50 years. The variability can be seen as anomalies of upper ocean density that appear in the Arctic and propagate to the North Atlantic. The density gradient in a northeast–southwest direction alternates with the density gradient in a northwest–southeast direction. A positive density anomaly in the Arctic is associated with a positive salinity anomaly, a positive surface temperature anomaly and a reduction of sea ice in the Barents and Kara Seas. The nature of the variability is a vertical advection of density by thermal currents similar to that proposed in Dijkstra et al (2008 Phil. Trans. R. Soc. A 366). The cycle of model variability shows that after a negative anomaly of density in the northwest Atlantic, one should expect warming in the Arctic in 5–10 years. The ensemble of decadal predictions with climate model INMCM4 starting from 1995 shows that warming in the western Arctic and especially in the Barents Sea observed in 1996–2010 can be reproduced by eight of ten ensemble members. Arctic climate predictability in this case is associated with a proposed mechanism of a 35–50 year North Atlantic–Arctic oscillation. (letter)

  6. The Atlantic Inflow through the Barents Sea from the high-resolution simulations

    Science.gov (United States)

    Aksenov, Y.; Bacon, S.; Coward, A. C.; Nurser, A. J. G.

    2009-04-01

    Atlantic Water is an important component of the Arctic Ocean circulation. To study Atlantic Water pathways we used the results of a high-resolution global sea ice-ocean simulations for the period 1985 - 2006. The simulations also included passive tracers and ventilation tracer analysis which demonstrated high ventilation of the Barents Sea at few localized sites. Mode waters of Barents Sea Water were identified: the first mode is formed at the shallow convective sites in the northern Barents Sea and contributes in the formation of the Arctic cold halocline water; the second mode is the source of the Arctic low halocline water and is formed in the southeastern Barents Sea; the third dense mode is formed west of Novaya Zemlya. The mode waters continue into the Eurasian Arctic through the northwestern Barents Sea and along the northern Barents Sea shelf, and, via the other route, through the southeastern Barents Sea and the St.Anna Trough. The formation rates of the mode waters along with the heat ans salt transports through the Barents Sea have been estimated and compared to observations. Keywords Arctic Ocean, Barents Sea, Atlantic Water, mode waters, ocean modelling

  7. Summer mean full depth circulation in North Atlantic Ocean along 59.5 N

    Science.gov (United States)

    Gladyshev, Vsevolod; Sokov, Alexey; Gladyshev, Sergey

    2016-04-01

    The large scale oceanic circulation in the North Atlantic is an important part of the climate system. Warm saline upper-ocean waters derived in subtropics release heat into the atmosphere while moving northward as North Atlantic Current and by mixing with colder fresher Arctic waters sink in the subpolar basins therefore originating reverse equatorward flow of cold fresh water. This mechanism, known as Atlantic Meridional Overturning Circulation (MOC) is of fundamental importance in the meridional heat transport. Using data from yearly direct hydrographic measurements at 59.5 N with satellite altimetry data in the period 2009-2015 a mean state of the full-depth summer circulation in the region is estimated. Zonal distribution of the 2009-2015 mean summer velocities across the 59.5 N is obtained using four different data sets from (1) pair of WS 300 kHz LADCPs measurements, (2) ship mounted TRDI OS 38 kHz ADCP measurements, (3) AVISO altimetry data (surface absolute geostrophic velocities), and (4) geostrophic velocities data calculated using CTD measurements. By combining those data mean absolute transport is estimated. Results are compared and analyzed confirming and elaborating previous research. Also assessment of the errors associated with full-depth ADCP profiles is settled. This evaluation allows arguing about certainty of collected data and can be used to improve accuracy of circulation rating.

  8. Deep water provenance and dynamics of the (de)glacial Atlantic meridional overturning circulation

    Science.gov (United States)

    Lippold, Jörg; Gutjahr, Marcus; Blaser, Patrick; Christner, Emanuel; de Carvalho Ferreira, Maria Luiza; Mulitza, Stefan; Christl, Marcus; Wombacher, Frank; Böhm, Evelyn; Antz, Benny; Cartapanis, Olivier; Vogel, Hendrik; Jaccard, Samuel L.

    2016-07-01

    Reconstructing past modes of ocean circulation is an essential task in paleoclimatology and paleoceanography. To this end, we combine two sedimentary proxies, Nd isotopes (εNd) and the 231Pa/230Th ratio, both of which are not directly involved in the global carbon cycle, but allow the reconstruction of water mass provenance and provide information about the past strength of overturning circulation, respectively. In this study, combined 231Pa/230Th and εNd down-core profiles from six Atlantic Ocean sediment cores are presented. The data set is complemented by the two available combined data sets from the literature. From this we derive a comprehensive picture of spatial and temporal patterns and the dynamic changes of the Atlantic Meridional Overturning Circulation over the past ∼25 ka. Our results provide evidence for a consistent pattern of glacial/stadial advances of Southern Sourced Water along with a northward circulation mode for all cores in the deeper (>3000 m) Atlantic. Results from shallower core sites support an active overturning cell of shoaled Northern Sourced Water during the LGM and the subsequent deglaciation. Furthermore, we report evidence for a short-lived period of intensified AMOC in the early Holocene.

  9. Delayed phenotypic expression of growth hormone transgenesis during early ontogeny in Atlantic salmon (Salmo salar?

    Directory of Open Access Journals (Sweden)

    Darek T R Moreau

    Full Text Available Should growth hormone (GH transgenic Atlantic salmon escape, there may be the potential for ecological and genetic impacts on wild populations. This study compared the developmental rate and respiratory metabolism of GH transgenic and non-transgenic full sibling Atlantic salmon during early ontogeny; a life history period of intense selection that may provide critical insight into the fitness consequences of escaped transgenics. Transgenesis did not affect the routine oxygen consumption of eyed embryos, newly hatched larvae or first-feeding juveniles. Moreover, the timing of early life history events was similar, with transgenic fish hatching less than one day earlier, on average, than their non-transgenic siblings. As the start of exogenous feeding neared, however, transgenic fish were somewhat developmentally behind, having more unused yolk and being slightly smaller than their non-transgenic siblings. Although such differences were found between transgenic and non-transgenic siblings, family differences were more important in explaining phenotypic variation. These findings suggest that biologically significant differences in fitness-related traits between GH transgenic and non-transgenic Atlantic salmon were less than family differences during the earliest life stages. The implications of these results are discussed in light of the ecological risk assessment of genetically modified animals.

  10. The North Atlantic Oscillation: variability and interactions with the North Atlantic ocean and Artic sea ice

    Energy Technology Data Exchange (ETDEWEB)

    Jung, T.

    2000-07-01

    The North Atlantic oscillation (NAO) represents the dominant mode of atmospheric variability in the North Atlantic region and describes the strengthening and weakening of the midlatitude westerlies. In this study, variability of the NAO during wintertime and its relationship to the North Atlantic ocean and Arctic sea ice is investigated. For this purpose, observational data are analyzed along with integrations of models for the Atlantic ocean, Arctic sea ice, and the coupled global climate system. From a statistical point of view, the observed NAO index shows unusually high variance on interdecadal time scales during the 20th century. Variability on other time scales is consistent with realizations of random processes (''white noise''). Recurrence of wintertime NAO anomalies from winter-to-winter with missing signals during the inbetween nonwinter seasons is primarily associated with interdecadal variability of the NAO. This recurrence indicates that low-frequency changes of the NAO during the 20th century were in part externally forced. (orig.)

  11. 76 FR 2640 - Fisheries of the Northeastern United States; Atlantic Bluefish Fishery; 2011 Atlantic Bluefish...

    Science.gov (United States)

    2011-01-14

    ... status quo management measures for 2011, which would result in a TAL identical to the 2010 TAL, or 29.264... analyzed three alternatives (including a no action/status quo alternative) for the 2011 Atlantic bluefish... recreational sector. Alternative 3 (status quo) would allocate 10.051 million lb (4,559 mt) to the...

  12. 77 FR 72762 - Atlantic Surfclam and Ocean Quahog Fisheries; 2013 Fishing Quotas for Atlantic Surfclams and...

    Science.gov (United States)

    2012-12-06

    ... Atlantic surfclam and ocean quahog fisheries for 2013 will remain status quo. Regulations governing these... INFORMATION CONTACT: Jason Berthiaume, Fishery Management Specialist, (978) 281-9177; fax (978) 281-9135. SUPPLEMENTARY INFORMATION: Section 648.72(c) of the regulations implementing the fishery management plan...

  13. 76 FR 65673 - Atlantic Highly Migratory Species; Atlantic Shark Management Measures; Correction

    Science.gov (United States)

    2011-10-24

    ... Register notice on October 7, 2011 (76 FR 62331). The notice also announced NMFS' intent to undertake... contains an error and is in need of correction. Correction Accordingly, in the October 7, 2011 (76 FR 62331... Species; Atlantic Shark Management Measures; Correction AGENCY: National Marine Fisheries Service...

  14. 76 FR 62331 - Atlantic Highly Migratory Species; Atlantic Shark Management Measures

    Science.gov (United States)

    2011-10-07

    ..., dusky, and blacknose sharks in the U.S. Atlantic and Gulf of Mexico were recently completed (76 FR 61092... (August 29, 2011, 76 FR 53652). Commercial regulations for blacknose sharks include, but are not limited... (May 4, 2010, 75 FR 23676). The Assessment Process was conducted via a series of webinars, during...

  15. 78 FR 54195 - Atlantic Highly Migratory Species; Atlantic Commercial Shark Fisheries

    Science.gov (United States)

    2013-09-03

    ... implemented and analyzed in the 2013 shark quota final rule (77 FR 75896, December 26, 2013) and in the final... Species; Atlantic Commercial Shark Fisheries AGENCY: National Marine Fisheries Service (NMFS), National.... SUMMARY: NMFS is transferring 68 metric tons (mt) dressed weight (dw) of non-blacknose small coastal...

  16. 77 FR 31562 - Atlantic Highly Migratory Species; Atlantic Shark Management Measures

    Science.gov (United States)

    2012-05-29

    ... October 7, 2011(76 FR 62331). This amendment is designed to rebuild and/or end overfishing on several... Species; Atlantic Shark Management Measures AGENCY: National Marine Fisheries Service (NMFS), National... considering the inclusion of Gulf of Mexico blacktip sharks in an amendment to the 2006 Consolidated...

  17. 78 FR 24148 - Atlantic Highly Migratory Species; Atlantic Shark Management Measures

    Science.gov (United States)

    2013-04-24

    ..., 2011 (76 FR 62331), we published an NOI that announced the stock status determinations for various... Magnuson-Stevens Act. On November 26, 2012, we published a proposed rule (77 FR 70552) for draft Amendment... Species; Atlantic Shark Management Measures AGENCY: National Marine Fisheries Service (NMFS),...

  18. 75 FR 57235 - Atlantic Highly Migratory Species; Atlantic Shark Management Measures

    Science.gov (United States)

    2010-09-20

    ... amendment is Amendment 3 to the 2006 Consolidated HMS FMP (75 FR 30484, June 1, 2010), which was based on... FR 250, January 5, 2010). Depending on the outcome of this ANPR process, NMFS will consider rules or... Species; Atlantic Shark Management Measures AGENCY: National Marine Fisheries Service (NMFS),...

  19. Some hydroids (Cnidaria: Hydrozoa) from the Mid-Atlantic Ridge, in the North Atlantic Ocean

    NARCIS (Netherlands)

    Calder, D.R.; Vervoort, W.

    1998-01-01

    An account is given of some hydroids from the Mid-Atlantic Ridge, collected during dives of submersibles "Nautile" (operated by IFREMER, France) and "Alvin" (operated by Woods Hole Oceanographic Institution, U.S.A). The specimens came from three main sectors of the ridge: 15 species from localities

  20. Ca2+ entry in gonadotrophs and alpha T3-1 cells: does store-dependent Ca2+ influx mediate gonadotrophin-releasing hormone action?

    Science.gov (United States)

    McArdle, C A; Forrest-Owen, W; Davidson, J S; Fowkes, R; Bunting, R; Mason, W T; Poch, A; Kratzmeier, M

    1996-04-01

    thapsigargin augmented the increase in [Ca2+]i seen on return to Ca(2+)-containing medium (to two- to threefold higher than that seen in control cells) indicating the activation of SDCI, whereas pool depletion by GnRH pretreatment had no such effect. To ensure maintained pool depletion after Ca2+ re-addition, similar studies were performed in which the thapsigargin and GnRH treatments were not washed off, but were retained through the period of return to Ca(2+)-containing medium. Return of GnRH-treated cells to Ca(2+)-containing medium caused an increase in [Ca2+]i which was inhibited by nicardipine, whereas the increase seen on return of thapsigargin-treated cells to Ca(2+)-containing medium was not reduced by nicardipine. The quench of fura-2 fluorescence by MnCl2 (used as a reporter of Ca2+ influx) was increased by GnRH and thapsigargin, indicating that both stimulate Ca2+ influx via Mn2+ permeant channels. The GnRH effect was abolished by nicardipine whereas that of thapsigargin was not. Finally, depletion of intracellular Ca2+ pools by pretreatment of superfused rat pituitary cells with GnRH or thapsigargin in Ca(2+)-free medium did not enhance LH release on return to Ca(2+)-containing medium. The results indicate that (a) thapsigargin stimulates SDCI in alpha T3-1 cells via nicardipine-insensitive Ca2+ channels, (b) in spite of the fact that GnRH depletes the hormone-mobilizable Ca2+ pool, it fails to stimulate SDCI, (c) GnRH stimulates Ca2+ entry predominantly via nicardipine-sensitive channels, a route not activated by SDCI and (d) in rat gonadotrophs, GnRH-stimulated LH release is not mediated by SDCI.

  1. Antarctic ice-rafted detritus (IRD) in the South Atlantic: Indicators of iceshelf dynamics or ocean surface conditions?

    Science.gov (United States)

    Nielsen, Simon H.H.; Hodell, D.A.

    2007-01-01

    Ocean sediment core TN057-13PC4/ODP1094, from the Atlantic sector of the Southern Ocean, contains elevated lithogenic material in sections representing the last glacial period compared to the Holocene. This ice-rafted detritus is mainly comprised of volcanic glass and ash, but has a significant input of what was previously interpreted as quartz during peak intervals (Kanfoush et al., 2000, 2002). Our analysis of these clear mineral grains indicates that most are plagioclase, and that South Sandwich Islands is the predominant source, similar to that inferred for the volcanic glass (Nielsen et al., in review). In addition, quartz and feldspar with possible Antarctic origin occur in conjunction with postulated episodes of Antarctic deglaciation. We conclude that while sea ice was the dominant ice rafting agent in the Polar Frontal Zone of the South Atlantic during the last glacial period, the Holocene IRD variability may reflect Antarctic ice sheet dynamics.

  2. 75 FR 74004 - Atlantic Highly Migratory Species; Advisory Panel

    Science.gov (United States)

    2010-11-30

    ... data and models, used in stock assessments for oceanic sharks in the Atlantic Ocean, Gulf of Mexico... but not limited to data and models, used in stock assessments for oceanic sharks in the Atlantic Ocean... sharks, it may be expanded to include other HMS, as needed. The primary purpose of the individuals in...

  3. Geophysical and geodynamic studies of the North Atlantic Realm

    DEFF Research Database (Denmark)

    Schiffer, Christian

    2015-01-01

    The geology of the North Atlantic Realm (NAR), including the North Atlantic, Greenland, the Arctic, Iceland, Scandinavia, Northern Europe and Northeast America has been studied for more than a century and inspired some of the most fundamental theories in geoscience, such as plate tectonics...

  4. 78 FR 36753 - North Atlantic Coast Comprehensive Study

    Science.gov (United States)

    2013-06-19

    ... Department of the Army; Corps of Engineers North Atlantic Coast Comprehensive Study AGENCY: Department of the Army, U.S. Army Corps of Engineers, DoD. ACTION: Notice of Study Initiation. SUMMARY: The Congressional.... The goals of the North Atlantic Coast Comprehensive Study authorized under the Disaster...

  5. 76 FR 166 - Fresh and Chilled Atlantic Salmon From Norway

    Science.gov (United States)

    2011-01-03

    ... imports of fresh and chilled Atlantic salmon from Norway (56 FR 14920, 14921). Following five-year reviews... imports of fresh and chilled Atlantic salmon from Norway (71 FR 7512). The Commission is now conducting...), as most recently amended at 74 FR 2847 (January 16, 2009). \\1\\ \\1\\ No response to this request...

  6. Mid-Atlantic Wind - Overcoming the Challenges

    Energy Technology Data Exchange (ETDEWEB)

    Daniel F. Ancona III; Kathryn E. George; Lynn Sparling; Bruce C. Buckheit; Daniel LoBue; and Richard P. Bowers

    2012-06-29

    This study, supported by the US Department of Energy, Wind Powering America Program, Maryland Department of Natural Resources and Chesapeake Bay Foundation, analyzed barriers to wind energy development in the Mid-Atlantic region along with options for overcoming or mitigating them. The Mid-Atlantic States including Delaware, Maryland, North Carolina and Virginia, have excellent wind energy potential and growing demand for electricity, but only two utility-scale projects have been installed to date. Reasons for this apathetic development of wind resources were analyzed and quantified for four markets. Specific applications are: 1) Appalachian mountain ridgeline sites, 2) on coastal plains and peninsulas, 3) at shallow water sites in Delaware and Chesapeake Bays, Albemarle and Pamlico Sounds, and 4) at deeper water sites off the Atlantic coast. Each market has distinctly different opportunities and barriers. The primary barriers to wind development described in this report can be grouped into four categories; state policy and regulatory issues, wind resource technical uncertainty, economic viability, and public interest in environmental issues. The properties of these typologies are not mutually independent and do interact. The report concluded that there are no insurmountable barriers to land-based wind energy projects and they could be economically viable today. Likewise potential sites in sheltered shallow waters in regional bay and sounds have been largely overlooked but could be viable currently. Offshore ocean-based applications face higher costs and technical and wind resource uncertainties. The ongoing research and development program, revision of state incentive policies, additional wind measurement efforts, transmission system expansion, environmental baseline studies and outreach to private developers and stakeholders are needed to reduce barriers to wind energy development.

  7. Mid-Atlantic Wind - Overcoming the Challenges

    Energy Technology Data Exchange (ETDEWEB)

    Daniel F. Ancona III; Kathryn E. George; Richard P. Bowers; Dr. Lynn Sparling; Bruce Buckheit; Daniel LoBue

    2012-05-31

    This study, supported by the US Department of Energy, Wind Powering America Program, Maryland Department of Natural Resources and Chesapeake Bay Foundation, analyzed barriers to wind energy development in the Mid-Atlantic region along with options for overcoming or mitigating them. The Mid-Atlantic States including Delaware, Maryland, North Carolina and Virginia, have excellent wind energy potential and growing demand for electricity, but only two utility-scale projects have been installed to date. Reasons for this apathetic development of wind resources were analyzed and quantified for four markets. Specific applications are: 1) Appalachian mountain ridgeline sites, 2) on coastal plains and peninsulas, 3) at shallow water sites in Delaware and Chesapeake Bays, Albemarle and Pamlico Sounds, and 4) at deeper water sites off the Atlantic coast. Each market has distinctly different opportunities and barriers. The primary barriers to wind development described in this report can be grouped into four categories; state policy and regulatory issues, wind resource technical uncertainty, economic viability, and public interest in environmental issues. The properties of these typologies are not mutually independent and do interact. The report concluded that there are no insurmountable barriers to land-based wind energy projects and they could be economically viable today. Likewise potential sites in sheltered shallow waters in regional bay and sounds have been largely overlooked but could be viable currently. Offshore ocean-based applications face higher costs and technical and wind resource uncertainties. The ongoing research and development program, revision of state incentive policies, additional wind measurement efforts, transmission system expansion, environmental baseline studies and outreach to private developers and stakeholders are needed to reduce barriers to wind energy development.

  8. Lattice Dynamics of fcc Ca

    DEFF Research Database (Denmark)

    Stassis, C.; Zaretsky, J.; Misemer, D. K.;;

    1983-01-01

    A large single crystal of FCC Ca was grown and was used to study the lattice dynamics of this divalent metal by coherent inelastic neutron scattering. The phonon dispersion curves were measured, at room temperature, along the [ξ00], [ξξ0], [ξξξ], and [0ξ1] symmetry directions. The dispersion curves...... bear a striking resemblance to those of FCC Yb, which is also a divalent metal with an electronic band structure similar to that of Ca. In particular, the shear moduli c44 and (c11-c 12)/2 differ by a factor of 3.4, which implies that FCC Ca (like FCC Yb) is very anisotropic with regard...... to the propagation of elastic waves. The frequencies of the T1[ξξ0] branch for ξ between approximately 0.5 and 0.8 are slightly above the velocity-of-sound line determined from the low-frequency measurements. Since a similar effect has been observed in FCC Yb, it is natural to assume that the anomalous dispersion...

  9. To Explore the Assessment and Related Factors of Cognitive Function MoCA of the Patients With Type I Bipolar Disorder in Stable Period of Psychotic Symptoms%精神病性症状的稳定期双相障碍I型患者认知功能MoCA评估及相关因素分析

    Institute of Scientific and Technical Information of China (English)

    周桂波

    2015-01-01

    目的:探讨与分析精神病性症状的稳定期双相障碍I型患者认知功能受损的相关原因。方法选择60例稳定期双相障碍I型精神病患者作为观察组,同时选取50例正常健康人作为对照组,分析患者认知功能受损原因。结果两组存在显著差异,P<0.05。结论患者的抑郁评分、狂躁评分与其认知功能情况存在一定的相关性。%ObjectiveTo investigate the related damage causes of cognitive function of patients with type I bipolar disorder in stable period of psychotic symptoms.Methods 60 cases of stable patients with type I bipolar disorder of mental illness were selected as the observation group, and 50 normal healthy people were selected as the control group. The reason of impaired cognitive function of the patients were analysis.Results Significant differences exist between the two groups,P<0.05.ConclusionThere is a correlation between scores of depression, manic scores and the impaired situation of cognitive function.

  10. Warm and Saline Events Embedded in the Meridional Circulation of the Northern North Atlantic

    Science.gov (United States)

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

    2011-01-01

    Ocean state estimates from 1958 to 2005 from the Simple Ocean Assimilation System (SODA) system are analyzed to understand circulation between subtropical and subpolar Atlantic and their connection with atmospheric forcing. This analysis shows three periods (1960s, around 1980, and 2000s) with enhanced warm, saline waters reaching high latitudes, alternating with freshwater events originating at high latitudes. It complements surface drifter and altimetry data showing the subtropical -subpolar exchange leading to a significant temperature and salinity increase in the northeast Atlantic after 2001. The warm water limb of the Atlantic meridional overturning cell represented by SODA expanded in density/salinity space during these warm events. Tracer simulations using SODA velocities also show decadal variation of the Gulf Stream waters reaching the subpolar gyre and Nordic seas. The negative phase of the North Atlantic Oscillation index, usually invoked in such variability, fails to predict the warming and salinization in the early 2000s, with salinities not seen since the 1960s. Wind stress curl variability provided a linkage to this subtropical/subpolar gyre exchange as illustrated using an idealized two ]layer circulation model. The ocean response to the modulation of the climatological wind stress curl pattern was found to be such that the northward penetration of subtropical tracers is enhanced when amplitude of the wind stress curl is weaker than normal. In this case both the subtropical and subpolar gyres weaken and the subpolar density surfaces relax; hence, the polar front moves westward, opening an enhanced northward access of the subtropical waters in the eastern boundary current.

  11. Multi-model ensemble analysis of Pacific and Atlantic SST variability in unperturbed climate simulations

    Science.gov (United States)

    Zanchettin, D.; Bothe, O.; Rubino, A.; Jungclaus, J. H.

    2016-08-01

    We assess internally-generated climate variability expressed by a multi-model ensemble of unperturbed climate simulations. We focus on basin-scale annual-average sea surface temperatures (SSTs) from twenty multicentennial pre-industrial control simulations contributing to the fifth phase of the Coupled Model Intercomparison Project. Ensemble spatial patterns of regional modes of variability and ensemble (cross-)wavelet-based phase-frequency diagrams of corresponding paired indices summarize the ensemble characteristics of inter-basin and regional-to-global SST interactions on a broad range of timescales. Results reveal that tropical and North Pacific SSTs are a source of simulated interannual global SST variability. The North Atlantic-average SST fluctuates in rough co-phase with the global-average SST on multidecadal timescales, which makes it difficult to discern the Atlantic Multidecadal Variability (AMV) signal from the global signal. The two leading modes of tropical and North Pacific SST variability converge towards co-phase in the multi-model ensemble, indicating that the Pacific Decadal Oscillation (PDO) results from a combination of tropical and extra-tropical processes. No robust inter- or multi-decadal inter-basin SST interaction arises from our ensemble analysis between the Pacific and Atlantic oceans, though specific phase-locked fluctuations occur between Pacific and Atlantic modes of SST variability in individual simulations and/or periods within individual simulations. The multidecadal modulation of PDO by the AMV identified in observations appears to be a recurrent but not typical feature of ensemble-simulated internal variability. Understanding the mechanism(s) and circumstances favoring such inter-basin SST phasing and related uncertainties in their simulated representation could help constraining uncertainty in decadal climate predictions.

  12. Modelling the chemically aged and mixed aerosols over the eastern central Atlantic Ocean – potential impacts

    Directory of Open Access Journals (Sweden)

    M. Astitha

    2010-07-01

    Full Text Available Detailed information on the chemical and physical properties of aerosols is important for assessing their role in air quality and climate. This work explores the origin and fate of continental aerosols transported over the Central Atlantic Ocean, in terms of chemical composition, number and size distribution, using chemistry-transport models, satellite data and in situ measurements. We focus on August 2005, a period with intense hurricane and tropical storm activity over the Atlantic Ocean. A mixture of anthropogenic (sulphates, nitrates, natural (desert dust, sea salt and chemically aged (sulphate and nitrate on dust aerosols is found entering the hurricane genesis region, most likely interacting with clouds in the area. Results from our modelling study suggest rather small amounts of accumulation mode desert dust, sea salt and chemically aged dust aerosols in this Atlantic Ocean region. Aerosols of smaller size (Aitken mode are more abundant in the area and in some occasions sulphates of anthropogenic origin and desert dust are of the same magnitude in terms of number concentrations. Typical aerosol number concentrations are derived for the vertical layers near shallow cloud formation regimes, indicating that the aerosol number concentration can reach several thousand particles per cubic centimetre. The vertical distribution of the aerosols shows that the desert dust particles are often transported near the top of the marine cloud layer as they enter into the region where deep convection is initiated. The anthropogenic sulphate aerosol can be transported within a thick layer and enter the cloud deck through multiple ways (from the top, the base of the cloud, and by entrainment. The sodium (sea salt related aerosol is mostly found below the cloud base. The results of this work may provide insights relevant for studies that consider aerosol influences on cloud processes and storm development in the Central Atlantic region.

  13. Chemically aged and mixed aerosols over the Central Atlantic Ocean – potential impacts

    Directory of Open Access Journals (Sweden)

    H. A. C. Denier van der Gon

    2010-02-01

    Full Text Available Detailed information on the chemical and physical properties of aerosols is important for assessing their role in air quality and climate. This work explores the origin and fate of continental aerosols transported over the Central Atlantic Ocean, in terms of chemical composition, number and size distribution, using chemistry-transport models, satellite data and in situ measurements. We focus on August 2005, a period with intense hurricane and tropical storm activity over the Atlantic Ocean. A mixture of anthropogenic (sulphates, nitrates, natural (desert dust, sea salt and chemically aged (sulphate and nitrate on dust aerosols is found entering the hurricane genesis region, most likely interacting with clouds in the area. Results from our modelling study suggest rather small amounts of accumulation mode desert dust, sea salt and chemically aged dust aerosols in this Atlantic Ocean region. Aerosols of smaller size (Aitken mode are more abundant in the area and in some occasions sulphates of anthropogenic origin and desert dust are of the same magnitude in terms of number concentrations. Typical aerosol number concentrations are derived for the vertical layers near shallow cloud formation regimes, designating that the aerosol number concentration can reach several thousand particles per cubic centimetre. The vertical distribution of the aerosols indicates that the desert dust particles are often transported near the top of the marine cloud layer as they enter into the region where deep convection is initiated. The anthropogenic sulphate aerosol can be transported within a thick layer and enter the cloud deck through multiple ways (from the top, the base of the cloud and entrainment. The sodium (sea salt related aerosol is mostly found below the cloud base. The results of this work may provide insights relevant for studies that consider aerosol influences on cloud processes and storm development in the Central Atlantic region.

  14. The Recent Increase in North Atlantic Hurricane Activity: Is it a Cycle or is it due to Global Warming?

    Science.gov (United States)

    Chelliah, M.; Bell, G.

    2006-12-01

    There has been a noticeable increase in North Atlantic hurricane activity since 1995. The devastating 2005 hurricane season broke many records with 27 tropical storms (TS), 15 hurricanes (H) and four category-5 major hurricanes (MH). This season also featured a record 15 landfalling storms in the Atlantic basin and four landfalling US major hurricanes (MH, defined as categories 3-5 on the Saffir-Simpson scale). Since 1995, North Atlantic hurricane seasons have averaged 13.1 TS, 7.4 H and 3.7 MH and according to NOAA, 9 of the 11 seasons have been termed above normal (active) seasons except for the two El Nino years 1997 and 2002. Prior to 1995, the North Atlantic basin experienced an overall inactive hurricane era from about 1971 to 1994 with an average 7.8 TS, 4.5H and 1.5 MH. But, prior to this inactive era (1971-1994) during the decades of the 1950's and 1960's (and in fact back to 1930's but with less reliable data) a typical season averaged about 8.0 TS, 5.4 H and 2.8 MH. As can be seen from these numbers, the seasonal averages for the number of TS, H, and MH during the recent active period since 1995 are overall higher than those during the earlier active decades of the 1950's and 1960's. These are no major disputes in these numbers. But there are differing views in the scientific community on the causal mechanisms (attribution) behind the recent increase in the North Atlantic hurricane activity. One view suggests that the recent increase is a return of the active hurricane cycle experienced in the past (such as the 1950's and 60's) and the other view suggesting that the increase could be due to global warming. This talk will focus on explaining, at least an attempt to explain, why there has been an increase in the overall hurricane activity since 1995. Based on recent published studies conducted at the Climate Prediction Center and elsewhere, it will be demonstrated that the answers to the ongoing debate, at least in the North Atlantic basin, is not as

  15. Assessing the impact of swimming exercise and the relative susceptibility of rainbow trout oncorhynchus mykiss (walbaum) and atlantic salmon salmo salar L. following injection challenge with weissella ceti

    Science.gov (United States)

    All-female rainbow trout and mixed-sex Atlantic salmon (approximately 200 g and 120 g initial weight, respectively) were maintained in small circular tanks in a flow-through system under study conditions for a period of five months. The four tank populations consisted of rainbow trout exposed to ei...

  16. Attempt to validate breakpoint MIC values estimated from pharmacokinetic data obtained during oxolinic acid therapy of winter ulcer disease in Atlantic salmon ( Salmo salar )

    DEFF Research Database (Denmark)

    Coyne, R.; Bergh, Ø.; Samuelsen, O.;

    2004-01-01

    Concentrations of oxolinic acid (OXA) were measured in the plasma, muscle, liver, and kidney of 48 Atlantic salmons (Salmo salar) 1 day after the end of an oral administration. OXA was administered over a period of 13 days to control an outbreak of winter ulcer disease in a commercial marine farm...

  17. Origin and fate of the North Atlantic Current at the Mid-Atlantic Ridge

    Science.gov (United States)

    Breckenfelder, Tilia; Myers, Paul G.; Rhein, Monika; Pennelly, Clark; Hu, Xianmin

    2016-04-01

    Warm, salty tropical and subtropical water is brought into the subpolar gyre by the North Atlantic Current (NAC). The NAC is the northward extension of the Gulf Stream and is part of the upper branch of the Atlantic Meridional Overturning Circulation. The warm, salty water is further transported into the Nordic Seas via the Rockall Trough, into the Denmark Strait and, finally into the Labrador Sea, where it plays an important role in the deep water formation process. On its way into the Labrador Sea the water mass increases its density by dissipating heat to the atmosphere and thereby influencing the local climate. To further understand the processes behind warm water transport towards higher latitudes, we start our investigation at the Mid-Atlantic Ridge (MAR). Here, the NAC flows from the western to eastern basin of the North Atlantic and crosses the MAR via the Charlie-Gibbs, Faraday and Maxwell Fracture Zones. The role of the subpolar and subtropical gyre on the different water masses, and their properties, originating or reaching the MAR is studied using the lagrangian tool ARIANE with the 3D velocity fields taken from a 1/12° AGRIF nest set in a regional NEMO configuration. One result of this investigation is that the majority of particles released at the MAR, distributed over the entire water column, recirculate. Most of the remaining particles make their way into the East Greenland Current or turn in the eastern basin towards the south. The influence of the North Atlantic Oscillation (NAO) is investigated by studying the pathways of the NAC and their properties during different NAO phases.

  18. Glacial climate sensitivity to different states of the Atlantic Meridional Overturning Circulation: results from the IPSL model

    Directory of Open Access Journals (Sweden)

    M. Kageyama

    2009-03-01

    Full Text Available Numerous records from the North Atlantic and the surrounding continents have shown rapid and large amplitude climate variability during the last glacial period. This variability has often been associated to changes in the Atlantic Meridional Overturning Circulation (AMOC. Rapid climate change on the same time scales has also been reconstructed for sites far away from the North Atlantic, such as the tropical Atlantic, the East Pacific and Asia. The mechanisms explaining these climatic responses to the state of the AMOC are far from being completely understood, especially in a glacial context. Here we study three glacial simulations characterised by different AMOC strengths: 18, 15 and 2 Sv. With these simulations, we analyse the global climate sensitivity to a weak (18 to 15 Sv and a strong (15 to 2 Sv decrease in the AMOC strength.

    A weak decrease in the AMOC is associated, in our model simulations, to the classical North Atlantic and European cooling, but this cooling is not homogeneous over this region. We investigate the reasons for a lesser cooling (or even slight warming in some cases over the Norwegian Sea and Northwestern Europe. It appears that the convection site in this area is active in both simulations, but that convection is unexpectedly stronger in the 15 Sv simulation. Due to the large variability of the atmosphere, it is difficult to definitely establish what is the origin of this climatic difference, but it appears that the atmospheric circulation anomaly helps sustaining the activity of this convection sites. Far from the North Atlantic, the climatic response is of small amplitude, the only significant change appearing in summer over the tropical Atlantic, where the Inter-Tropical Convergence Zone (ITCZ shifts southward.

    The climate differences between the 15 Sv and 2 Sv simulations are much larger and our analyses focus on three areas: the North Atlantic and surrounding regions, the Tropics and the Indian

  19. The early Holocene humid period in the Tayma palaeolake, NW Arabian Peninsula -- A high-resolution micro-facies and geochemical approach

    Science.gov (United States)

    Neugebauer, Ina; Plessen, Birgit; Dinies, Michèle; Engel, Max; Tjallingii, Rik; Brauer, Achim

    2016-04-01

    The Tayma palaeolake is a rare archive of the early Holocene humid period in northern Arabia (Dinies et al. 2015; Engel et al. 2012). Here we present a ca. 1 m thick and 500 years spanning annually laminated sediment section that was deposited in the centre of the former lake from ca. 8500 to 8000 calibrated years (cal. yrs) BP, as determined by AMS 14C dating of pollen concentrates (Dinies et al. 2015). High-resolution micro-facies analyses based on thin section microscopy, μXRF element scanning, δ18Ocarb and δ13Ccarb measurements on single carbonate laminae, as well as geochemical measurements on bulk samples for TOC, CaCO3, C/N ratio, δ18Ocarb, δ13Ccarb, δ13Corg and δ15N determination were performed in order to investigate the sedimentological and geochemical changes along the varved sequence in great detail. The finely laminated marl sediments are mainly composed of sub-mm thick laminae of endogenic aragonite, organic matter and diatoms, as well as occasional, often graded silt-clay layers. Following an early lake phase from ca. 8700 to 8500 cal. yrs BP characterized by coarsely laminated, presumably non-annual marl sediments that are rich in ostracods, three main varved phases can be distinguished within the investigated section: (1) aragonitic-organic varves from ca. 8500 to 8300 cal. yrs BP, (2) diatom-organic varves from ca. 8300 to 8100 cal. yrs BP that frequently include aragonite laminae and occasionally gastropod and ostracod shells, and (3) organic varves from ca. 8100 to 8000 cal. yrs BP with decreasing diatom and aragonite laminae and an increasing frequency of gypsum layers. After this period, gypsum becomes abundant and fine lamination appears only sporadically. In addition, we observe increasing trends of TOC, C/N and δ13Ccarb and decreasing δ18Ocarb during phase 1 and excess δ18Ocarb, δ13Ccarb and TOC values during phase 2, pointing towards the maximum lake productivity and increased seasonal precipitation. We interpret this

  20. Climate reconstruction for the last two millennia in central Iberia: The role of East Atlantic (EA), North Atlantic Oscillation (NAO) and their interplay over the Iberian Peninsula

    Science.gov (United States)

    Sánchez-López, G.; Hernández, A.; Pla-Rabes, S.; Trigo, R. M.; Toro, M.; Granados, I.; Sáez, A.; Masqué, P.; Pueyo, J. J.; Rubio-Inglés, M. J.; Giralt, S.

    2016-10-01

    A multi-proxy characterization of the uppermost sedimentary infill of an Iberian alpine lake (Cimera, 2140 m a.s.l.) was performed to establish the climatic and environmental conditions for the Iberian Central Range (ICR) over the last two millennia. This multi-proxy characterization was used to reconstruct the intense runoff events, lake productivity and soil erosion in the lake catchment and interpret these factors in terms of temperature and precipitation variability. The Roman Period (RP; 200 BCE - 500 CE) beginning was characterized by an alternation between cold and warm periods as indicated by short-lived oscillations of intense runoff conditions and soil erosion, although warm conditions dominated the end of the period and the Early Middle Age (EMA; 500-900 CE) onset in the ICR. A noticeable decrease in intense runoff events and a progressive decrease in soil erosion during the late EMA indicated a shift to colder temperatures. In terms of precipitation, both the RP and EMA climate periods displayed a transition from dry to wet conditions that led to a decrease in lake productivity. The Medieval Climate Anomaly (MCA; 900-1300 CE) was characterized by warm and dry conditions with frequent intense runoff episodes and increases in lake productivity and soil erosion, whereas the Little Ice Age (LIA; 1300-1850 CE) showed the opposite characteristics. The Industrial Era (1850-2012 CE) presented an increase in lake productivity that likely demonstrates the influence of global warming. The spatio-temporal integration of the Cimera record with other Iberian reconstructions has been used to identify the main climate drivers over this region. During the RP and EMA, N-S and E-W humidity gradients were dominant, whereas during the MCA and LIA, these gradients were not evident. These differences could be ascribed to interactions between the North Atlantic Oscillation (NAO) and East Atlantic (EA) phases. During the RP, the general warm conditions and the E-W humidity

  1. Seafloor Asymmetry in the Atlantic Ocean

    Institute of Scientific and Technical Information of China (English)

    S.S.Gao; K.H.Liu

    2004-01-01

    Measurements of seafloor asymmetry at about 360000 pairs of conjugate points along 1250 profiles across the mid-Atlantic Ridge(MAR)provide new constraints on models for the upwelling of the buoyant asthenosphere. The sign and amplitude of the asymmetry vary systematically and are functions of the distance between the spreading center and the location of the inferred location of maximum regional buoyancy(LMRB)in the asthenosphere. The LMRB is a smooth line derived from the observed asymmetry and is more centered at the regional topographic high than the spreading center. These observations are best explained by active upwelling of the underlying buoyant asthenosphere rather than by pressure-release melting.

  2. MACKINDER'S "HEARTLAND" THEORY AND THE ATLANTIC COMMUNITY

    OpenAIRE

    Sharapova, Sevara

    2005-01-01

    The term "Atlantic partnership" refers to the strong diplomatic and military links between the U.S. and major Western European countries such as Great Britain, Germany and France. The union established by these countries has been durable and reliable, especially during the Cold War. The European allies consistently supported the U.S. in military actions. However, in spite of dependence on the U.S., even during the Cold War the European states had many trade conflicts with the United States. N...

  3. Periodic solutions of periodically harvested lotka-volterra systems

    OpenAIRE

    Hausrath, Alan R.; Manasevich, Raul F.

    2012-01-01

    We study a Lotka-Volterra system with periodic harvesting, find sufficient conditions for the existence of periodic solutions with the same period, and, under certain conditions, count the number of such periodic solutions.

  4. Time evolution of the South Atlantic Magnetic Anomaly

    Directory of Open Access Journals (Sweden)

    Gelvam A. Hartmann

    2009-06-01

    Full Text Available The South Atlantic Magnetic Anomaly (SAMA is one of the most outstanding anomalies of the geomagnetic field. The SAMA secular variation was obtained and compared to the evolution of other anomalies using spherical harmonic field models for the 1590-2005 period. An analysis of data from four South American observatories shows how this large scale anomaly affected their measurements. Since SAMA is a low total field anomaly, the field was separated into its nondipolar, quadrupolar and octupolar parts. The time evolution of the non-dipole/total, quadrupolar/total and octupolar/total field ratios yielded increasingly high values for the South Atlantic since 1750. The SAMA evolution is compared to the evolution of other large scale surface geomagnetic features like the North and the South Pole and the Siberia High, and this comparison shows the intensity equilibrium between these anomalies in both hemispheres. The analysis of non-dipole fields in historical period suggests that SAMA is governed by (i quadrupolar field for drift, and (ii quadrupolar and octupolar fields for intensity and area of influence. Furthermore, our study reinforces the possibility that SAMA may be related to reverse fluxes in the outer core under the South Atlantic region.A Anomalia Magnética do Atlântico Sul (SAMA é uma das maiores anomalias do campo geomagnético. A variação secular da SAMA foi obtida e comparada com a evolução de outrasanomalias usando modelos de campo por harmônicos esféricos para o período de 1590-2005. Uma análise dos dados de quatro observatórios da América do Sul mostra como esta anomalia de grande escala afetou suas medidas. Como a SAMA é uma anomalia de campo total baixo, o campo foi separado nas componentes não-dipolar, quadrupolar e octupolar. A evolução temporal das razões dos campos não-dipolar/total, quadrupolar/total e octupolar/total mostram valores elevados para o Atlântico Sul desde 1750. A evolução da SAMA é comparada

  5. North Atlantic Deep Water Production during the Last Glacial Maximum

    Science.gov (United States)

    Howe, Jacob N. W.; Piotrowski, Alexander M.; Noble, Taryn L.; Mulitza, Stefan; Chiessi, Cristiano M.; Bayon, Germain

    2016-06-01

    Changes in deep ocean ventilation are commonly invoked as the primary cause of lower glacial atmospheric CO2. The water mass structure of the glacial deep Atlantic Ocean and the mechanism by which it may have sequestered carbon remain elusive. Here we present neodymium isotope measurements from cores throughout the Atlantic that reveal glacial-interglacial changes in water mass distributions. These results demonstrate the sustained production of North Atlantic Deep Water under glacial conditions, indicating that southern-sourced waters were not as spatially extensive during the Last Glacial Maximum as previously believed. We demonstrate that the depleted glacial δ13C values in the deep Atlantic Ocean cannot be explained solely by water mass source changes. A greater amount of respired carbon, therefore, must have been stored in the abyssal Atlantic during the Last Glacial Maximum. We infer that this was achieved by a sluggish deep overturning cell, comprised of well-mixed northern- and southern-sourced waters.

  6. Interannual to multidecadal Euro-Atlantic blocking variability during winter and its relationship with extreme low temperatures in Europe

    OpenAIRE

    Rimbu, Norel; Lohmann, Gerrit; Ionita, Monica

    2014-01-01

    The dominant modes of blocking frequency variability in the Atlantic-European region are evaluated for the 1871–2010 period. An Empirical Orthogonal Function (EOF) analysis of a two-dimensional blocking indicator field reveals three dominant EOFs, describing about 35% of interannual to multidecadal blocking variability. The first EOF captures an out-of-phase blocking frequency anomaly over Greenland and Western Europe regions. The corresponding principal component time series is strongly corr...

  7. Drumlin evolution and ice sheet oscillations along the NE Atlantic margin, Donegal Bay, western Ireland

    Science.gov (United States)

    Knight, Jasper; McCabe, A. Marshall

    1997-07-01

    Satellite imagery of Donegal Bay, northwestern Ireland, reveals two streamlined subglacial bedform sets produced during the late Devensian glaciation (ca. 22,000-15,000 yrs B.P.). The first bedform set trends northeast-southwest and records fast ice flow from inland ice domes onto the eastern Atlantic continental shelf. The second bedform set, trending east-west, crosscuts and partially reorientates the first. Morphological and sedimentary evidence show that the second set corresponds to the last phase of fast ice flow (drumlinization) in northwestern Ireland. Morphological characteristics of the Donegal Bay drumlin field, and sedimentary characteristics of the Mullinasole drumlin, Donegal Bay, support a two-stage interpretation of drumlin evolution. These are the following. (1) Deposition of glaciomarine mud and diamict facies at a tidewater glacier margin. Stratified diamicts record debris flow events and sediment reworking. This facies sequence is erosionally truncated. (2) Deposition of subglacial diamict and sand facies recording ice readvance and drumlinization. Drumlinization (sediment streamlining) reflects ice mass-balance destabilization, episodic: fast ice flow and ice-marginal oscillation, and may be correlated with millennial-time scale climate changes in the circum-North Atlantic.

  8. [Effect of polycarbophil Ca on IBS].

    Science.gov (United States)

    Mine, Tetsuya

    2006-08-01

    In this chapter, I mentioned the effect of polycarbophil Ca on IBS. IBS is classified into 3 types; diarrhea type, constipation type and combined type. Polycarbophil Ca is effective for all types of IBS.

  9. Gas bubble disease mortality of Atlantic menhaden, Brevoortia tyrannus, at a coastal nuclear power plant

    International Nuclear Information System (INIS)

    A substantial mortality of Atlantic menhaden, Brevoortia tyrannus, occurred in the discharge channel and discharge plume area of the Boston Edison Company's Pilgrim Nuclear Power Station Unit 1 during the period April 8 through April 24, 1973. Gas bubble disease was implicated as the cause of their death. Measurements of dissolved gas concentration of the station's intake and discharge water during this fish mortality are presented. Observations on the behavior and results of the pathological examination of menhaden afflicted with gas embolism are discussed

  10. Effect of Warm Atlantic Waters on the Climate Anomalies in the West Arctic

    Directory of Open Access Journals (Sweden)

    A. N. Zolotokrylin

    2015-01-01

    Full Text Available Significant climatic changes of oceanic and atmospheric elements and a relation of them to the ocean surface winter anomalies in North Atlantic are analyzed in the paper. Periods of «warm» ocean (2002–2012 and «cold» ocean (1960–1970 were determined. Positive anomalies of the ocean surface temperature increase the ice-free water area and, correspondingly, decrease the ice-field area. As a result of such changes in a state of the ocean surface (open water and ice, surface air temperature rises, and, consequently, atmospheric pressure in central part of a given Arctic sector drops.

  11. Spatial Pattern of North Atlantic Oscillation Impact on Rainfall in Serbia

    Science.gov (United States)

    Lukovic, J.; Blagojevic, D.; Kilibarda, M.; Bajat, B.

    2015-12-01

    This study examines the spatial pattern of relationships between annual, seasonal and monthly rainfall in Serbia, and the North Atlantic Oscillation (NAO) for the period of 1961-2009. The first correlation analysis between rainfall and the NAO was performed using a Pearson product-moment test. Results suggested negative, mainly statistically significant correlations at annual and winter scales as was expected. However, the highest percentage of stations showed significant result in October suggesting a strong impact of a large scale atmospheric mode throughout a wet season in Serbia. Further spatial analysis that incorporated a spatial autocorrelation statistic of correlation coefficients showed significant clustering at all temporal scales.

  12. Migration Pathways, Behavioural Thermoregulation and Overwintering Grounds of Blue Sharks in the Northwest Atlantic

    OpenAIRE

    Campana, Steven E.; Anna Dorey; Mark Fowler; Warren Joyce; Zeliang Wang; Dan Wright; Igor Yashayaev

    2011-01-01

    The blue shark Prionace glauca is the most abundant large pelagic shark in the Atlantic Ocean. Although recaptures of tagged sharks have shown that the species is highly migratory, migration pathways towards the overwintering grounds remain poorly understood. We used archival satellite pop-up tags to track 23 blue sharks over a mean period of 88 days as they departed the coastal waters of North America in the autumn. Within 1-2 days of entering the Gulf Stream (median date of 21 Oct), all sha...

  13. Spatiotemporal SNP analysis reveals pronounced biocomplexity at the northern range margin of Atlantic cod Gadus morhua

    DEFF Research Database (Denmark)

    Therkildsen, Nina Overgaard; Hansen, Jakob Hemmer; Hedeholm, R.B.;

    2013-01-01

    Accurate prediction of species distribution shifts in the face of climate change requires a sound understanding of population diversity and local adaptations. Previous modeling has suggested that global warming will lead to increased abundance of Atlantic cod (Gadus morhua) in the ocean around...... Greenland, but the dynamics of earlier abundance fluctuations are not well understood. We applied a retrospective spatiotemporal population genomics approach to examine the temporal stability of cod population structure in this region and to search for signatures of divergent selection over a 78-year period...

  14. Spontaneous periodic hypothermia.

    Science.gov (United States)

    Kloos, R T

    1995-09-01

    Spontaneous periodic hypothermia is a rare syndrome of recurrent, centrally mediated hypothermia without an identifiable systemic cause or brain lesion. Most patients defend a temporarily lowered temperature "set point" during episodes of hypothermia, despite manifesting many well-known systemic consequences of core temperature hypothermia. No case of death directly attributable to an episode of spontaneous periodic hypothermia has been reported, although many of the serious systemic effects of hypothermia have been documented in these cases, so it is not unlikely that death may occur. The syndrome's cause, and that of Shapiro syndrome, remains unknown. Pharmacologic trials to date have been only modestly successful. Anticonvulsant agents, clonidine, and cyproheptadine appear the most likely to succeed, with cyproheptadine being a reasonable first choice. Given that the term "spontaneous periodic hypothermia" describes a syndrome, and not a pathophysiologic mechanism, it is likely to encompass a common eventuality, arrived at via several different pathways. One can postulate mechanisms such as structural abnormalities, trauma, infection, irritation, and degeneration involving strategic locations which create a focus for epileptic or other periodic dysfunction whose scope involves the centers for thermoregulation. The existence of 2 distinct, oppositional thermoregulatory centers would allow for speculation of similar mechanisms accounting for cases of both periodic hypo- and hyperthermia (61). Postmortem data regarding the hypothalamic and surrounding areas from future cases of Shapiro syndrome and spontaneous periodic hypothermia would be of great interest. Further, more sensitive in vivo testing methods are clearly needed. The role of PET or single photon emission computed tomography (SPECT) with technetium 99m-labeled hexamethylpropylene amine oxime (Tc 99m HMPAO) performed acutely during an episode remains to be characterized (64, 103, 105). The term

  15. Periodically kicked turbulence

    Science.gov (United States)

    Lohse

    2000-10-01

    Periodically kicked turbulence is theoretically analyzed within a mean-field theory. For large enough kicking strength A and kicking frequency f the Reynolds number grows exponentially and then runs into some saturation. The saturation level Re(sat) can be calculated analytically; different regimes can be observed. For large enough Re we find Re(sat) approximately Af, but intermittency can modify this scaling law. We suggest an experimental realization of periodically kicked turbulence to study the different regimes we theoretically predict and thus to better understand the effect of forcing on fully developed turbulence. PMID:11089041

  16. Continental shelf processes affecting the oceanography of the South Atlantic Bight. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Pietrafesa, L.J.

    1978-03-01

    The objectives of the project were to determine the physical/dynamical processes controlling/affecting the distribution of phytoplankton nutrients on the continental shelf in the South Atlantic Bight. The initial objectives were to determine the short term, i.e., 2 to 10 day and longer term flux of nutrients onto the continental shelf. This is clearly related to the more general problem of combined physical and biogenic control of phytoplankton nutrients. During the period from June, 1975 to March, 1978 the study of the continental shelf processes affecting the oceanography of the South Atlantic Bight has been principally involved with a substantial, coordinated field effort. The success of the data acquisition phase of the program has now required an intensive data analysis phase which has been slowly increasing in effort. Emphasis is placed on the main phase of the field program, located in Onslow Bay, which has beel completed and the data are being analyzed. During the three-year period 20 cruises were made into the Carolina Capes area and samples were collected. A list is included of some 100 publications during the period.

  17. Limited response of peatland CH4 emissions to abrupt Atlantic Ocean circulation changes in glacial climates

    Directory of Open Access Journals (Sweden)

    P. O. Hopcroft

    2013-06-01

    Full Text Available Ice-core records show that abrupt Dansgaard-Oeschger climatic warming events of the last glacial period were accompanied by large increases in the atmospheric CH4 concentration (up to 200 ppbv. These abrupt changes are generally regarded as arising from the effects of changes in the Atlantic Ocean meridional overturning circulation and the resultant climatic impact on natural CH4 sources, in particular wetlands. We use two different ecosystem models of wetland CH4 emissions to simulate northern CH4 sources forced with coupled general circulation model simulations of five different time periods during the last glacial to investigate the potential influence of abrupt ocean circulation changes on atmospheric CH4 levels during D-O events. The simulated warming over Greenland of 7–9 °C in the different time-periods is at the lower end of the range of 11–15 °C derived from ice-cores, but is associated with strong impacts on the hydrological cycle, especially over the North Atlantic and Europe during winter. We find that although the sensitivity of CH4 emissions to the imposed climate varies significantly between the two ecosystem emissions models, the model simulations do not reproduce sufficient emission changes to satisfy ice-core observations of CH4 increases during abrupt events. This suggests that alternative scenarios of climatic change could be required to explain the abrupt glacial CH4 variations.

  18. New evidence of shared dinosaur across Upper Jurassic Proto-North Atlantic: Stegosaurus from Portugal

    Science.gov (United States)

    Escaso, Fernando; Ortega, Francisco; Dantas, Pedro; Malafaia, Elisabete; Pimentel, Nuno L.; Pereda-Suberbiola, Xabier; Sanz, José Luis; Kullberg, José Carlos; Kullberg, María Carla; Barriga, Fernando

    2007-05-01

    More than one century after its original description by Marsh in 1877, we report in this paper the first uncontroversial evidence of a member of the genus Stegosaurus out of North America. The specimen consists of a partial skeleton from the Upper Jurassic of Portugal, herein considered as Stegosaurus cf. ungulatus. The presence of this plated dinosaur in the upper Kimmeridgian-lower Tithonian Portuguese record and synchronic levels of the Morrison Formation of North America reinforces previous hypothesis of a close relationship between these two areas during the Late Jurassic. This relationship is also supported by geotectonic evidences indicating high probability of an episodic corridor between the Newfoundland and Iberian landmasses. Together, Portuguese Stegosaurus discovery and geotectonic inferences could provide a scenario with episodical faunal contact among North Atlantic landmasses during the uppermost Kimmeridgian-lowermost Tithonian (ca. 148-153 Ma ago).

  19. CA-CA互操作研究%Research of CA-CA Interoperability

    Institute of Scientific and Technical Information of China (English)

    沈士根; 叶培松; 陈宝明

    2005-01-01

    文章介绍了国际上CA-CA之间实现互操作的信任模式,然后根据中国目前的PKI实际情况,提出了以桥CA为全局模式,局部可采用严格层次信任模式来实现各CA之间的互操作.

  20. Prenatal nicotine and maternal deprivation stress de-regulate the development of CA1, CA3, and dentate gyrus neurons in hippocampus of infant rats.

    Directory of Open Access Journals (Sweden)

    Hong Wang

    Full Text Available Adverse experiences by the developing fetus and in early childhood are associated with profound effects on learning, emotional behavior, and cognition as a whole. In this study we investigated the effects of prenatal nicotine exposure (NIC, postnatal maternal deprivation (MD or the combination of the two (NIC+MD to determine if hippocampal neuron development is modulated by exposure to drugs of abuse and/or stress. Growth of rat offspring exposed to MD alone or NIC+MD was repressed until after weaning. In CA1 but not CA3 of postnatal day 14 (P14 pups, MD increased pyramidal neurons, however, in dentate gyrus (DG, decreased granule neurons. NIC had no effect on neuron number in CA1, CA3 or DG. Unexpectedly, NIC plus MD combined caused a synergistic increase in the number of CA1 or CA3 neurons. Neuron density in CA regions was unaffected by treatment, but in the DG, granule neurons had a looser packing density after NIC, MD or NIC+MD exposure. When septotemporal axes were analyzed, the synergism of stress and drug exposure in CA1 and CA3 was associated with rostral, whereas MD effects were predominantly associated with caudal neurons. TUNEL labeling suggests no active apoptosis at P14, and doublecortin positive neurons and mossy fibers were diminished in NIC+MD relative to controls. The laterality of the effect of nicotine and/or maternal deprivation in right versus left hippocampus was also analyzed and found to be insiginificant. We report for the first time that early life stressors such as postnatal MD and prenatal NIC exposure, when combined, may exhibit synergistic consequences for CA1 and CA3 pyramidal neuron development, and a potential antagonistic influence on developing DG neurons. These results suggest that early stressors may modulate neurogenesis, apoptosis, or maturation of glutamatergic neurons in the hippocampus in a region-specific manner during critical periods of neurodevelopment.

  1. Historical DNA reveals the demographic history of Atlantic cod (Gadus morhua) in medieval and early modern Iceland.

    Science.gov (United States)

    Ólafsdóttir, Guðbjörg Ásta; Westfall, Kristen M; Edvardsson, Ragnar; Pálsson, Snæbjörn

    2014-02-22

    Atlantic cod (Gadus morhua) vertebrae from archaeological sites were used to study the history of the Icelandic Atlantic cod population in the time period of 1500-1990. Specifically, we used coalescence modelling to estimate population size and fluctuations from the sequence diversity at the cytochrome b (cytb) and Pantophysin I (PanI) loci. The models are consistent with an expanding population during the warm medieval period, large historical effective population size (NE), a marked bottleneck event at 1400-1500 and a decrease in NE in early modern times. The model results are corroborated by the reduction of haplotype and nucleotide variation over time and pairwise population distance as a significant portion of nucleotide variation partitioned across the 1550 time mark. The mean age of the historical fished stock is high in medieval times with a truncation in age in early modern times. The population size crash coincides with a period of known cooling in the North Atlantic, and we conclude that the collapse may be related to climate or climate-induced ecosystem change.

  2. Structures of CaV2 Ca2+/CaM-IQ Domain Complexes Reveal Binding Modes That Underlie Calcium-Dependent Inactivation And Facilitation

    International Nuclear Information System (INIS)

    Calcium influx drives two opposing voltage-activated calcium channel (CaV) self-modulatory processes: calcium-dependent inactivation (CDI) and calcium-dependent facilitation (CDF). Specific Ca2+/calmodulin (Ca2+/CaM) lobes produce CDI and CDF through interactions with the CaVα1 subunit IQ domain. Curiously, Ca2+/CaM lobe modulation polarity appears inverted between CaV1s and CaV2s. Here, we present crystal structures of CaV2.1, CaV2.2, and CaV2.3 Ca2+/CaM-IQ domain complexes. All display binding orientations opposite to CaV1.2 with a physical reversal of the CaM lobe positions relative to the IQ α-helix. Titration calorimetry reveals lobe competition for a high-affinity site common to CaV1 and CaV2 IQ domains that is occupied by the CDI lobe in the structures. Electrophysiological experiments demonstrate that the N-terminal CaV2 Ca2+/C-lobe anchors affect CDF. Together, the data unveil the remarkable structural plasticity at the heart of CaV feedback modulation and indicate that CaV1 and CaV2 IQ domains bear a dedicated CDF site that exchanges Ca2+/CaM lobe occupants

  3. Evidence for a Long-period Planet Orbiting Epsilon Eridani

    CERN Document Server

    Hatzes, A P; McArthur, B E; Baliunas, S L; Walker, G A H; Campbell, B; Irwin, A W; Yang, S; Kürster, M; Endl, M; Els, S; Butler, R P; Marcy, G W; Hatzes, Artie P.; Cochran, William D.; Arthur, Barbara Mc; Baliunas, Sallie L.; Walker, Gordon A. H.; Campbell, Bruce; Irwin, Alan W.; Yang, Stephenson; Endl, Michael; Els, Sebastian; Marcy, Geoffrey W.

    2000-01-01

    High precision radial velocity (RV) measurements spanning the years 1980.8--2000.0 are presented for the nearby (3.22 pc) K2 V star $\\epsilon$ Eri. These data, which represent a combination of six independent data sets taken with four different telescopes, show convincing variations with a period of $\\approx$ 7 yrs. A least squares orbital solution using robust estimation yields orbital parameters of period, $P$ = 6.9 yrs, velocity $K$-amplitude $=$ 19 {\\ms}, eccentricity $e$ $=$ 0.6, projected companion mass $M$ sin $i$ = 0.86 $M_{Jupiter}$, and semi-major axis $a_2$ $=$ 3.3 AU. Ca II H&K S-index measurements spanning the same time interval show significant variations with periods of 3 and 20 yrs, yet none at the RV period. If magnetic activity were responsible for the RV variations then it produces a significantly different period than is seen in the Ca II data. Given the lack of Ca II variation with the same period as that found in the RV measurements, the long-lived and coherent nature of these variat...

  4. Tectonic provinces of the Atlantic Ocean

    Science.gov (United States)

    Pushcharovsky, Yu. M.

    2009-05-01

    The tectonic structure of the floor of the Atlantic Ocean beyond the continental margins is insufficiently studied. This is also true of its tectonic demarcation. The segmentation of the floor into regional-scale tectonic provinces of several orders proposed in this paper is primarily based on structural and historical geological features. It is shown that deep oceanic basins and fault tectonics are of particular importance in this respect. Tectonic provinces of two orders are distinguished by a set of attributes. The first-order provinces are the North, Central, South, and Antarctic domains of the Atlantic Ocean. They are separated by wide demarcation fracture zones into Transatlantic (transverse) second-order tectonic provinces. Ten such provinces are recognized (from the north southward): Greenland-Lofoten, Greenland-Scandinavia, Greenland-Ireland, Newfoundland-European, North American-African, Antilles-African, Angola-Brazil, Cape-Argentine, North Antarctic, and South Antarctic. This subdivision demonstrates significant differentiation in the geodynamic state of the oceanic lithosphere that determines nonuniform ocean formation and the tectonic features of the ocean floor. The latitudinal orientation of the second-order provinces inherits the past tectonic pattern, though newly formed structural units cannot be ruled out. The Earth rotation exerts a crucial effect on the crust and the mantle.

  5. Kinematics of the South Atlantic rift

    CERN Document Server

    Heine, Christian; Müller, R Dietmar

    2013-01-01

    The South Atlantic rift basin evolved as branch of a large Jurassic-Cretaceous intraplate rift zone between the African and South American plates during the final breakup of western Gondwana. By quantitatively accounting for crustal deformation in the Central and West African rift zone, we indirectly construct the kinematic history of the pre-breakup evolution of the conjugate West African-Brazilian margins. Our model suggests a causal link between changes in extension direction and velocity during continental extension and the generation of marginal structures such as the enigmatic Pre-salt sag basin and the S\\~ao Paulo High. We model an initial E-W directed extension between South America and Africa (fixed in present-day position) at very low extensional velocities until Upper Hauterivian times ($\\approx$126 Ma) when rift activity along in the equatorial Atlantic domain started to increase significantly. During this initial $\\approx$17 Myr-long stretching episode the Pre-salt basin width on the conjugate Br...

  6. The enigmatic whale: the North Atlantic humpback

    Directory of Open Access Journals (Sweden)

    Tim D Smith

    2013-10-01

    Full Text Available We know more about the North Atlantic humpback whale (Megaptera novaeangliae than we do for virtually any other cetacean, yet attempts to use this information to describe the status of the populations in this ocean basin have not proven satisfactory. The North Atlantic humpback has been the subject of extensive research over the past few decades, resulting in a substantial amount of knowledge about what has proven to be a species with a very complex life history and population structure. While several population models have been developed to integrate the available information, the data overall are not well described by any of the models. This has left considerable uncertainty about population status, and has raised questions about the interpretation of some of the data. We describe 7 specific areas where puzzling or ambiguous observations have been made; these require closer attention if population status is to be determined. These areas raise several fundamental questions, including: How many breeding populations are there? How much do the populations mix on the feeding grounds? How has the distribution of animals on both feeding and breeding grounds changed? We identify additional research needed to address the 7 areas and these questions in particular, so that population status might be determined.

  7. Periodic paralysis complicating malaria.

    OpenAIRE

    Senanayake, N; Wimalawansa, S J

    1981-01-01

    Episodic muscular weakness, commonly associated with alterations of serum potassium, is the cardinal feature of periodic paralysis. The combination of transient hyperkalaemia and rigors occurring during febrile episodes of malaria is suggested as the underlying cause which precipitated the muscular paralysis. Three patients with malaria who developed a similar paralysis during the paroxysms of fever are described to illustrate this.

  8. Periodic Table of Students.

    Science.gov (United States)

    Johnson, Mike

    1998-01-01

    Presents an exercise in which an eighth-grade science teacher decorated the classroom with a periodic table of students. Student photographs were arranged according to similarities into vertical columns. Students were each assigned an atomic number according to their placement in the table. The table is then used to teach students about…

  9. Treatment for periodic paralysis

    NARCIS (Netherlands)

    Sansone, [No Value; Meola, G.; Links, T. P.; Panzeri, M.; Rose, M. R.

    2008-01-01

    Background Primary periodic paralyses are rare inherited muscle diseases characterised by episodes of flaccid weakness affecting one or more limbs, lasting several hours to several days, caused by mutations in skeletal muscle channel genes. Objectives The objective of this review was to systematical

  10. Scheduling: Seven Period Day

    Science.gov (United States)

    Williamson, Ronald

    2010-01-01

    Driven by stable or declining financial resources many school districts are considering the costs and benefits of a seven-period day. While there is limited evidence that any particular scheduling model has a greater impact on student learning than any other, it is clear that the school schedule is a tool that can significantly impact teacher…

  11. Wave Extremes in the North East Atlantic from Ensemble Forecasts

    CERN Document Server

    Breivik, Øyvind; Bidlot, Jean-Raymond; Carrasco, Ana; Saetra, Øyvind; 10.1175/JCLI-D-12-00738.1

    2013-01-01

    A method for estimating return values from ensembles of forecasts at advanced lead times is presented. Return values of significant wave height in the North-East Atlantic, the Norwegian Sea and the North Sea are computed from archived +240-h forecasts of the ECMWF ensemble prediction system (EPS) from 1999 to 2009. We make three assumptions: First, each forecast is representative of a six-hour interval and collectively the data set is then comparable to a time period of 226 years. Second, the model climate matches the observed distribution, which we confirm by comparing with buoy data. Third, the ensemble members are sufficiently uncorrelated to be considered independent realizations of the model climate. We find anomaly correlations of 0.20, but peak events (>P97) are entirely uncorrelated. By comparing return values from individual members with return values of subsamples of the data set we also find that the estimates follow the same distribution and appear unaffected by correlations in the ensemble. The a...

  12. Acoustic habitat of an oceanic archipelago in the Southwestern Atlantic

    Science.gov (United States)

    Bittencourt, Lis; Barbosa, Mariana; Secchi, Eduardo; Lailson-Brito, José; Azevedo, Alexandre

    2016-09-01

    Underwater soundscapes can be highly variable, and in natural conditions are often dominated by biological signals and physical features of the environment. Few studies, however, focused on oceanic islands soundscapes. Islands in the middle of ocean basins can provide a good example of how untouched marine soundscapes are. Autonomous acoustic recordings were carried out in two different seasons in Trindade-Martin Vaz Archipelago, Southwestern Atlantic, providing nearly continuous data for both periods. Sound levels varied daily and between seasons. During summer, higher frequencies were noisier than lower frequencies, with snapping shrimp being the dominating sound source. During winter, lower frequencies were noisier than higher frequencies due to humpback whale constant singing. Biological signal detection had a marked temporal pattern, playing an important role in the soundscape. Over 1000 humpback whale sounds were detected hourly during winter. Fish vocalizations were detected mostly during night time during both summer and winter. The results show an acoustic habitat dominated by biological sound sources and highlight the importance of the island to humpback whales in winter.

  13. Investigating annual diving behaviour by hooded seals (Cystophora cristata within the Northwest Atlantic Ocean.

    Directory of Open Access Journals (Sweden)

    Julie M Andersen

    Full Text Available With the exception of relatively brief periods when they reproduce and moult, hooded seals, Cystophora cristata, spend most of the year in the open ocean where they undergo feeding migrations to either recover or prepare for the next fasting period. Valuable insights into habitat use and diving behaviour during these periods have been obtained by attaching Satellite Relay Data Loggers (SRDLs to 51 Northwest (NW Atlantic hooded seals (33 females and 18 males during ice-bound fasting periods (2004-2008. Using General Additive Models (GAMs we describe habitat use in terms of First Passage Time (FPT and analyse how bathymetry, seasonality and FPT influence the hooded seals' diving behaviour described by maximum dive depth, dive duration and surface duration. Adult NW Atlantic hooded seals exhibit a change in diving activity in areas where they spend >20 h by increasing maximum dive depth, dive duration and surface duration, indicating a restricted search behaviour. We found that male and female hooded seals are spatially segregated and that diving behaviour varies between sexes in relation to habitat properties and seasonality. Migration periods are described by increased dive duration for both sexes with a peak in May, October and January. Males demonstrated an increase in dive depth and dive duration towards May (post-breeding/pre-moult and August-October (post-moult/pre-breeding but did not show any pronounced increase in surface duration. Females dived deepest and had the highest surface duration between December and January (post-moult/pre-breeding. Our results suggest that the smaller females may have a greater need to recover from dives than that of the larger males. Horizontal segregation could have evolved as a result of a resource partitioning strategy to avoid sexual competition or that the energy requirements of males and females are different due to different energy expenditure during fasting periods.

  14. 50 CFR 622.18 - South Atlantic snapper-grouper limited access.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false South Atlantic snapper-grouper limited... ATLANTIC Effort Limitations § 622.18 South Atlantic snapper-grouper limited access. (a) General. The only valid commercial vessel permits for South Atlantic snapper-grouper are those that have been issued...

  15. The Majorqaq Belt: A record of Neoarchaean orogenesis during final assembly of the North Atlantic Craton, southern West Greenland

    Science.gov (United States)

    Dyck, Brendan; Reno, Barry L.; Kokfelt, Thomas F.

    2015-04-01

    Over the past 4.5 billion years (Ga) the Earth has undergone a secular change in tectonic regimes. Archaean tectonics was a markedly different process than observed today, involving a hotter planet with a thinner lithosphere, thicker oceanic crust, and smaller proto-continents. The transition to a more modern type of plate tectonics required the initiation of subduction of oceanic lithosphere. The onset of subduction in the Meso- to Neoarchaean (ca. 3.2 to 2.5 Ga) is shown by geochemical signatures indicative of crustal recycling and petrologic evidence of tectonically driven thickening of the continental crust. This transition is recorded in the rock record of the North Atlantic Craton, which preserves a history of crust formation through to terrane accretion and the collision of crustal blocks. Here we present petrologic, chronologic, chemical and geophysical evidence from the Majorqaq Belt, a ~ 100 km wide east-west striking zone, defined by a high gravity anomaly, voluminous metasedimentary units, olivine-rich ultramafic enclaves, and anomalously high K2O, Ni, and MgO stream-sediment chemistry. We use a 207Pb/206Pb zircon LA-ICP-MS age of 2.557 ± 0.005 Ga (2σ) from an upper-amphibolite facies metapelitic migmatite to propose Neoarchaean suturing of the Maniitsoq crustal block to the North Atlantic Craton. Ti-in-zircon temperatures and zircon-garnet REE distribution coefficients constrain zircon crystallisation to 815-729 °C, which is at, or near the solidus during leucosome crystallisation. Our data reveal a clockwise P-T path with a high-pressure assemblage of garnet-kyanite-plagioclase-rutile-biotite-quartz which grew at an apparent thermal gradient of ~ 660 °C/GPa during subduction-driven compression of surface-derived sediments to a minimum-peak-pressure of ~ 1.15 GPa at ~ 760 °C followed by the growth of gedrite-cordierite-sillimanite-ilmenite at minimum-peak-temperature conditions of ~ 810 °C at ~ 0.94 GPa. We propose the evolution of the Majorqaq

  16. Opening of the Arctic-North Atlantic Gateway

    Science.gov (United States)

    Engen, O.; Faleide, J. I.; Eldholm, O.; Breivik, A.

    2003-12-01

    The ˜150 km wide Fram Strait between Svalbard and Greenland is the only deep-water connection between the Arctic and the world oceans. It is essential for the thermohaline `engine' of the North Atlantic circulation system, pulling warm surface water north along the European coasts while returning cold, saline bottom water from the Arctic. Moreover, it contains a series of short, ultra-slow spreading segments and right-lateral transform faults, connecting the Gakkel Ridge to the rest of the Mid-Atlantic Ridge system. While the ridges to the north and south started spreading near the Paleocene-Eocene transition ( ˜55 Ma), the plate boundary between Svalbard and Greenland underwent shear and a transpressive orogeny. Only after the earliest Oligocene ( ˜33 Ma), when the Greenland plate became attached to North America and the rotation pole moved, the entire plate boundary became divergent. However, the final opening of the Fram Strait gateway was delayed for several reasons: First, basement terraces on the western Svalbard margin were downfaulted post-Eocene, witnessing a pre-breakup crustal thinning period that may have lasted for 15-20 m.y. Second, transform segments formed continental bridges for several m.y. after breakup on the ridge segments; the deep-water passage was not established before continental outliers were separated by young oceanic crust across all transform faults. Third, the Hovgaard microcontinent, which was split off the western Barents Sea-Svalbard margin, may have restricted water circulation for some time. By integrating gravity, bathymetry, magnetic and reflection seismic data we locate the positions of present and extinct spreading axes, as well as the continent-ocean transition (COT) on the Svalbard side. The COT correlates with a steep gradient in the Bouguer gravity anomaly, which is taken as a proxy COT on the sparsely surveyed Greenland side. By testing different rotation poles we arrive at a regionally consistent plate kinematic

  17. Shifting distributions of adult Atlantic sturgeon amidst post-industrialization and future impacts in the Delaware River: a maximum entropy approach.

    Directory of Open Access Journals (Sweden)

    Matthew W Breece

    Full Text Available Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus experienced severe declines due to habitat destruction and overfishing beginning in the late 19(th century. Subsequent to the boom and bust period of exploitation, there has been minimal fishing pressure and improving habitats. However, lack of recovery led to the 2012 listing of Atlantic sturgeon under the Endangered Species Act. Although habitats may be improving, the availability of high quality spawning habitat, essential for the survival and development of eggs and larvae may still be a limiting factor in the recovery of Atlantic sturgeon. To estimate adult Atlantic sturgeon spatial distributions during riverine occupancy in the Delaware River, we utilized a maximum entropy (MaxEnt approach along with passive biotelemetry during the likely spawning season. We found that substrate composition and distance from the salt front significantly influenced the locations of adult Atlantic sturgeon in the Delaware River. To broaden the scope of this study we projected our model onto four scenarios depicting varying locations of the salt front in the Delaware River: the contemporary location of the salt front during the likely spawning season, the location of the salt front during the historic fishery in the late 19(th century, an estimated shift in the salt front by the year 2100 due to climate change, and an extreme drought scenario, similar to that which occurred in the 1960's. The movement of the salt front upstream as a result of dredging and climate change likely eliminated historic spawning habitats and currently threatens areas where Atlantic sturgeon spawning may be taking place. Identifying where suitable spawning substrate and water chemistry intersect with the likely occurrence of adult Atlantic sturgeon in the Delaware River highlights essential spawning habitats, enhancing recovery prospects for this imperiled species.

  18. Cells anticipate periodic events

    Science.gov (United States)

    Nakagaki, Toshiyuki

    2009-03-01

    We show that an amoeboid organism can anticipate the timing of periodic events. The plasmodium of the true slime mold Physarum polycephalum moves rapidly under favourable conditions, but stops moving when transferred to less-favourable conditions. Plasmodia exposed to unfavourable conditions, presented in three consecutive pulses at constant intervals, reduced their locomotive speed in response to each episode. When subsequently subjected to favourable conditions, the plasmodia spontaneously reduced their locomotive speed at the time point when the next unfavourable episode would have occurred. This implied anticipation of impending environmental change. After this behaviour had been evoked several times, the locomotion of the plasmodia returned to normal; however, the anticipatory response could subsequently be induced by a single unfavourable pulse, implying recall of the memorized periodicity. We explored the mechanisms underlying these behaviours from a dynamical systems perspective. Our results hint at the cellular origins of primitive intelligence and imply that simple dynamics might be sufficient to explain its emergence.

  19. Comparative study of CA242 and CA19-9 for the diagnosis of pancreatic cancer.

    OpenAIRE

    Kawa, S; Tokoo, M.; Hasebe, O.; Hayashi, K.; Imai, H; Oguchi, H.; Kiyosawa, K; Furuta, S; Homma, T

    1994-01-01

    A comparative study of a new tumour marker, CA242, and CA19-9 was conducted with special reference to their diagnostic usefulness in pancreatic cancer. CA242 showed sensitivity similar to that of CA19-9 for overall cases and early cases (stage I tumour) of pancreatic cancer. For other malignancies, the positive rates of CA242 were lower than those of CA19-9 except for colorectal cancer. An important characteristics of CA242 was that it was only slightly and infrequently elevated in the sera o...

  20. Testing coral paleothermometers (B/Ca, Mg/Ca, Sr/Ca, U/Ca andδ18O) under impacts of large riverine runoff

    Institute of Scientific and Technical Information of China (English)

    CHEN Tianran; YU Kefu; ZHAO Jianxin; YAN Hongqiang; SONG Yinxian; FENG Yuexing; CHEN Tegu

    2015-01-01

    Sea surface temperature (SST) proxies including B/Ca, Mg/Ca, Sr/Ca, U/Ca andδ18O were analyzed in the skeleton of aPorites coral collected from the Zhujiang River (Pearl River) Estuary (ZRE). These geochemical proxies are influenced by river runoff and this area of the northern South China Sea is strongly affected by seasonal freshwater floods. We assessed the robustness of each SST proxy through comparison with the local instrumental SST. Coral Sr/Ca shows the highest correlation with SST variations (r2=0.59), suggesting Sr/Ca is the most robust SST proxy. In contrast, coralδ18O (r2=0.46), B/Ca (r2=0.43) and U/Ca (r2=0.41) ratios were only moderately correlated with SST variations, suggesting that they are disturbed by some other factors in addition to SST. The poor correlation (r2=0.27) between SST and Mg/Ca indicates that Mg/Ca in coral skeletons is not a simple function of SST variations. This may ultimately limit the use of Mg/Ca as a coral paleothermometer.

  1. A neural network-based estimate of the seasonal to inter-annual variability of the Atlantic Ocean carbon sink

    Science.gov (United States)

    Landschützer, P.; Gruber, N.; Bakker, D. C. E.; Schuster, U.; Nakaoka, S.; Payne, M. R.; Sasse, T. P.; Zeng, J.

    2013-11-01

    The Atlantic Ocean is one of the most important sinks for atmospheric carbon dioxide (CO2), but this sink has been shown to vary substantially in time. Here we use surface ocean CO2 observations to estimate this sink and the temporal variability from 1998 through 2007 in the Atlantic Ocean. We benefit from (i) a continuous improvement of the observations, i.e. the Surface Ocean CO2 Atlas (SOCAT) v1.5 database and (ii) a newly developed technique to interpolate the observations in space and time. In particular, we use a two-step neural network approach to reconstruct basin-wide monthly maps of the sea surface partial pressure of CO2 (pCO2) at a resolution of 1° × 1°. From those, we compute the air-sea CO2 flux maps using a standard gas exchange parameterization and high-resolution wind speeds. The neural networks fit the observed pCO2 data with a root mean square error (RMSE) of about 10 μatm and with almost no bias. A check against independent time-series data and new data from SOCAT v2 reveals a larger RMSE of 22.8 μatm for the entire Atlantic Ocean, which decreases to 16.3 μatm for data south of 40° N. We estimate a decadal mean uptake flux of -0.45 ± 0.15 Pg C yr-1 for the Atlantic between 44° S and 79° N, representing the sum of a strong uptake north of 18° N (-0.39 ± 0.10 Pg C yr-1), outgassing in the tropics (18° S-18° N, 0.11 ± 0.07 Pg C yr-1), and uptake in the subtropical/temperate South Atlantic south of 18° S (-0.16 ± 0.06 Pg C yr-1), consistent with recent studies. The strongest seasonal variability of the CO2 flux occurs in the temperature-driven subtropical North Atlantic, with uptake in winter and outgassing in summer. The seasonal cycle is antiphased in the subpolar latitudes relative to the subtropics largely as a result of the biologically driven winter-to-summer drawdown of CO2. Over the 10 yr analysis period (1998 through 2007), sea surface pCO2 increased faster than that of the atmosphere in large areas poleward of 40° N

  2. Scattering of periodic solitons

    Energy Technology Data Exchange (ETDEWEB)

    Cova, R.J. [Carleton University, School of Mathematics and Statistics, 1125 Colonel by Drive, Ottawa, Ontario K1S 5B6 (Canada); Zakrzewski, W.J. [University of Durham, Dept. of Mathematical Sciences, Durham DH1 3LE (United Kingdom)]. e-mail: rcova@math.carleton.ca

    2004-07-01

    Through numerical simulations we study N-soliton scattering (N = 3, 4) in the (2 + 1)-dimensional CP{sup 1} model with periodic boundary conditions. Solitons colliding from symmetrical configurations scatter at {pi}/ N, as observed in the usual model with standard boundary conditions. When the initial configurations are not symmetric the angles differ from {pi}/ N. We describe our observed patterns based on a properly formulated geodesic approximation. (Author) 11 refs., 10 figs.

  3. Multiple Ca2+ sensors in secretion

    DEFF Research Database (Denmark)

    Walter, Alexander M; Groffen, Alexander J; Sørensen, Jakob Balslev;

    2011-01-01

    Regulated neurotransmitter secretion depends on Ca(2+) sensors, C2 domain proteins that associate with phospholipids and soluble N-ethylmaleimide-sensitive fusion attachment protein receptor (SNARE) complexes to trigger release upon Ca(2+) binding. Ca(2+) sensors are thought to prevent spontaneous...... fusion at rest (clamping) and to promote fusion upon Ca(2+) activation. At least eight, often coexpressed, Ca(2+) sensors have been identified in mammals. Accumulating evidence suggests that multiple Ca(2+) sensors interact, rather than work autonomously, to produce the complex secretory response...... observed in neurons and secretory cells. In this review, we present several working models to describe how different sensors might be arranged to mediate synchronous, asynchronous and spontaneous neurotransmitter release. We discuss the scenario that different Ca(2+) sensors typically act on one shared...

  4. Periodic minimal surfaces

    Science.gov (United States)

    Mackay, Alan L.

    1985-04-01

    A minimal surface is one for which, like a soap film with the same pressure on each side, the mean curvature is zero and, thus, is one where the two principal curvatures are equal and opposite at every point. For every closed circuit in the surface, the area is a minimum. Schwarz1 and Neovius2 showed that elements of such surfaces could be put together to give surfaces periodic in three dimensions. These periodic minimal surfaces are geometrical invariants, as are the regular polyhedra, but the former are curved. Minimal surfaces are appropriate for the description of various structures where internal surfaces are prominent and seek to adopt a minimum area or a zero mean curvature subject to their topology; thus they merit more complete numerical characterization. There seem to be at least 18 such surfaces3, with various symmetries and topologies, related to the crystallographic space groups. Recently, glyceryl mono-oleate (GMO) was shown by Longley and McIntosh4 to take the shape of the F-surface. The structure postulated is shown here to be in good agreement with an analysis of the fundamental geometry of periodic minimal surfaces.

  5. North and South Atlantic Bidecadal SL variability: Rossby Waves, AMOC fingerprints and Regime Shifts

    Science.gov (United States)

    Vianna, M. L.; Menezes, V. V.

    2014-12-01

    The relationship between the North and South Atlantic bidecadal sea level (SL) oscillations in the twentieth century (1908-2008) is investigated using SODA 2.2.4 reanalysis and 102 monthly mean SL time series from TG stations provided by PSMSL. Bidecadal SL signal extraction was done using our method of subjectively choosing groupings of space-time data into non-overlapping period bands by use of Singular Spectrum Analysis (SSA)/ Maximum Entropy Method (MEM) analysis. A CEOF analysis of the SODA bidecadal band shows dominance of 22-24 year periods. Propagating bidecadal mode expansions were then determined through this analysis, which gives two principal modes. The first mode is dominant from 1915 to 1965 and the second from 1970 onward. The amplitude variabilities obtained suggests the presence of regime shifts, which coincide in time with shifts actually observed in European climate and South African lobster fisheries. The first mode is characterized by states with North and South Atlantic subtropical gyres in phase, while tropical and subpolar regions are in opposite phase relative to them. The second mode is characterized by the subpolar gyre and North subtropical gyre almost in quadrature, with North and South subtropical gyres out of phase. The evolution mechanism of this latter mode is related to east-west density contrasts and westward propagating Rossby waves. These waves show phase speeds dominated by geostrophic self-advection of density anomalies relative to the mean meridional density gradient as known from previous studies, but are shown to be additionally influenced by bottom topography. The oscillations caused by these waves are shown to have phase differences (quadrature in the North Atlantic) with regional indices of bidecadal AMOC oscillations. A number of SL-AMOC fingerprints are also reviewed, and a new eastern equatorial fingerprint is proposed.

  6. Implication of eolian delivery and accumulation of highly reactive iron to the Atlantic Ocean

    Science.gov (United States)

    Lee, B. K.; Owens, J. D.; Lyons, T. W.

    2014-12-01

    Iron, although abundant in the Earth's crust, is present at low concentrations in sea water and is a limiting nutrient for phytoplankton. Eolian dust (loess) is a major source of this micronutrient, and its deposition has important implications for the global CO2 budget. In this study, we explore distributions of potentially bioreactive Fe, the soluble fraction required by phytoplankton for photosynthesis and nitrogen assimilation, in deep-sea sediments in the North and South Atlantic Oceans. We used a state-of-the-art Fe speciation technique to characterize Fe inputs from different source regions, specifically North Africa and Patagonia to address the patterns and implications across glacial-interglacial time scales. In many open-ocean regions the input of new iron to the surface waters is dominated by the atmospheric deposition of soluble iron in eolian dusts. Multiple records have shown dust accumulation is correlated with glacial-interglacial cycles - glacial periods are substantially dustier. Furthermore, the delivery of eolian dust to the North and South Atlantic Oceans are from two very different source regions and soil types. We analyzed IODP cores from these two regions and our preliminary data shows similar pattern of iron distribution from both the North and South Atlantic Oceans. To date we have found no simple global pattern of bioavailable iron distribution during glacial and interglacial periods. We have analyzed a range of size distributions to isolate the dust-dominated fraction and the data shows no size effects in bioavailable form of iron distribution. We will explore the role of deep-water dust dissolution and sedimentary redox implications and its role on the bioreactive Fe record in marine cores.

  7. Analysing migrations of Atlantic cod Gadus morhua in the north‐east Atlantic Ocean

    DEFF Research Database (Denmark)

    Neuenfeldt, S.; Righton, D.; Neat, F.;

    2013-01-01

    descriptions, separation of reproductively isolated populations, timing and areas of spawning, tidal transport and use of protected areas. The examples are based on archival tag data from the North Sea, the Baltic Sea, the Barents Sea and Faroese and Icelandic Waters. Besides presenting the state......-of-the-art geolocations for cod Gadus morhua in the north-east Atlantic Ocean, the major aim of this review is to raise awareness of gaps in knowledge and to identify ideas for new research...

  8. South Atlantic island record reveals a South Atlantic response to the 8.2 kyr event

    OpenAIRE

    Ljung, K.; Björck, S.; Renssen, H.; D. Hammarlund

    2007-01-01

    International audience One of the most distinct climate fluctuations during the Holocene is the short and rapid event centred around 8200 years ago, the 8.2 kyr event, which was most likely triggered by glacial melt-water forcing from the receding Laurentide ice-sheet. Evidence for this cooling has primarily been reported from sites around the North Atlantic, but an increasing number of observations imply a more wide-spread occurrence. Palaeoclimate archives from the Southern Hemisphere ha...

  9. Evolution of Temperature and Carbon Storage Within the Deep Southeast Atlantic Ocean Across the Last Glacial/Interglacial Cycle Inferred from a Highly-Resolved Sedimentary Depth Transect

    Science.gov (United States)

    Foreman, A. D.; Charles, C. D.; Rae, J. W. B.; Adkins, J. F.; Slowey, N. C.

    2015-12-01

    Many models show that the relative intensity of stratification is a primary variable governing the sequestration and release of carbon from the ocean over ice ages. The wide-scale observations necessary to test these model-derived hypotheses are not yet sufficient, but sedimentary depth transects represent a promising approach for making progress. Here we present paired stable isotopic (d18O, d13C) and trace metal data (Mg/Ca, B/Ca) from benthic foraminifera collected from a highly vertically-resolved depth transect from the mid-depth and deep SE Atlantic. These observations, which cover Marine Isotope Stages 5e, 5d, 5a, 4, and the Last Glacial Maximum, document the evolution of glacial conditions from the previous interglacial, and provide detailed observations regarding the magnitude and timing of changes in temperature and salinity within the deep ocean at key time points over the last glacial/interglacial cycle. Furthermore, the comparison between purely 'physical' tracers (i.e. Mg/Ca, d18O) and tracers sensitive to the carbon cycle (i.e. d13C and B/Ca) provides critical insight into the relationship between deep/mid-depth stratification and global carbon dynamics. Notably among our observations, the paired stable isotope and trace metal results strongly suggest that much of the ice-age cooling of deep South Atlantic occurred at the MIS 5e/5d transition, while the onset of salinity stratification in the mid-depth South Atlantic occurred at the MIS 5/4 transition.

  10. AMO-like variations of holocene sea surface temperatures in the North Atlantic Ocean

    OpenAIRE

    Feng, S; Hu, Q; Oglesby, R. J.

    2009-01-01

    Instrumental records of the North Atlantic sea surface temperatures (SST) show a significant 60–80 year cycle, referred to as the Atlantic Multidecadal Oscillation (AMO). During AMO warm (cold) phases, SST over the entire North Atlantic Ocean is dominated by basin-wide positive (negative) anomalies. We analyzed SST variations in the North Atlantic Ocean for the last 10 ka. The long-term and centennial variations of Holocene SST in the North Atlantic demonstrate a basin-wide mode that clearly ...

  11. South Atlantic island record reveals a South Atlantic response to the 8.2 kyr event

    Directory of Open Access Journals (Sweden)

    K. Ljung

    2007-05-01

    Full Text Available One of the most distinct climate fluctuations during the Holocene is the short and rapid event centred around 8200 years ago, the 8.2 kyr event, which was most likely triggered by glacial melt-water forcing from the receding Laurentide ice-sheet. Evidence for this cooling has primarily been reported from sites around the North Atlantic, but an increasing number of observations imply a more wide-spread occurrence. Palaeoclimate archives from the Southern Hemisphere have hitherto failed to uncover a distinct climatic anomaly associated with the 8.2 kyr event. Here we present a lake sediment record from Nightingale Island in the central South Atlantic showing enhanced precipitation between 8275 and 8025 cal. yrs BP, most likely as a consequence of increased sea surface temperature (SST. We show that this is consistent with climate model projections of a warming of the South Atlantic in response to reduced north-ward energy transport during the 8.2 kyr event.

  12. South Atlantic island record reveals a South Atlantic response to the 8.2 kyr event

    Directory of Open Access Journals (Sweden)

    K. Ljung

    2008-02-01

    Full Text Available One of the most distinct climate fluctuations during the Holocene is the short and rapid event centred around 8200 years ago, the 8.2 kyr event, which was most likely triggered by glacial melt-water forcing from the receding Laurentide ice-sheet. Evidence for this cooling has primarily been reported from sites around the North Atlantic, but an increasing number of observations imply a more wide-spread occurrence. Palaeoclimate archives from the Southern Hemisphere have hitherto failed to uncover a distinct climatic anomaly associated with the 8.2 kyr event. Here we present a lake sediment record from Nightingale Island in the central South Atlantic showing enhanced precipitation between 8275 and 8025 cal. yrs BP, most likely as a consequence of increased sea surface temperature (SST. We show that this is consistent with climate model projections of a warming of the South Atlantic in response to reduced north-ward energy transport during the 8.2 kyr event.

  13. Segment-specific Ca(2+) transport by isolated Malpighian tubules of Drosophila melanogaster: A comparison of larval and adult stages.

    Science.gov (United States)

    Browne, Austin; O'Donnell, Michael J

    2016-04-01

    Haemolymph calcium homeostasis in insects is achieved through the regulation of calcium excretion by Malpighian tubules in two ways: (1) sequestration of calcium within biomineralized granules and (2) secretion of calcium in soluble form within the primary urine. Using the scanning ion-selective electrode technique (SIET), basolateral Ca(2+) transport was measured at the distal, transitional, main and proximal tubular segments of anterior tubules isolated from both 3rd instar larvae and adults of the fruit fly Drosophila melanogaster. Basolateral Ca(2+) transport exceeded transepithelial secretion by 800-fold and 11-fold in anterior tubules of larvae and adults, respectively. The magnitude of Ca(2+) fluxes across the distal tubule of larvae and adults were larger than fluxes across the downstream segments by 10 and 40 times, respectively, indicating a dominant role for the distal segment in whole animal Ca(2+) regulation. Basolateral Ca(2+) transport across distal tubules of Drosophila varied throughout the life cycle; Ca(2+) was released by distal tubules of larvae, taken up by distal tubules of young adults and was released once again by tubules of adults ⩾ 168 h post-eclosion. In adults and larvae, SIET measurements revealed sites of both Ca(2+) uptake and Ca(2+) release across the basolateral surface of the distal segment of the same tubule, indicating that Ca(2+) transport is bidirectional. Ca(2+) uptake across the distal segment of tubules of young adults and Ca(2+) release across the distal segment of tubules of older adults was also suggestive of reversible Ca(2+) storage. Our results suggest that the distal tubules of D. melanogaster are dynamic calcium stores which allow efficient haemolymph calcium regulation through active Ca(2+) sequestration during periods of high dietary calcium intake and passive Ca(2+) release during periods of calcium deficiency. PMID:26802560

  14. ENSO influence on the North Atlantic European climate: a non-linear and non-stationary approach

    Science.gov (United States)

    López-Parages, Jorge; Rodríguez-Fonseca, Belén; Dommenget, Dietmar; Frauen, Claudia

    2016-10-01

    El Niño Southern Oscillation (ENSO) impact on the North Atlantic European sector (NAE) is still under discussion. Recent studies have found a non stationary feature of this teleconnection, suggesting an effective modulating role of the ocean mean state. Nevertheless, physical explanations about the underlying mechanisms have been little studied in the available literature. In addition, ENSO events show different SST spatial patterns, phases, and amplitudes, which can also influence on the related remote impacts. In view of all this, in the present study a set of partially coupled experiments have been performed with a global atmospheric general circulation model in which different SST ENSO patterns are superimposed over distinct Pacific and Atlantic SST mean states. These SST background conditions are constructed according to the observational difference between periods with a distinct impact of ENSO on the leading Euro-Mediterranean rainfall mode in late winter-early spring. Our results point to two distinct mechanisms associated with ENSO that can be modulated by the SST mean state: (1) the thermally driven direct circulation (Walker and Hadley cells) connecting the Atlantic and Pacific basins, and (2) the Rossby wave propagation from the tropical Pacific to the North Atlantic. The former elucidates that the positive NAO-like pattern usually related to La Niña events could be only valid for selected decades. The latter explains a reinforced signature of Eastern Pacific Niños on the Euro-Mediterranean rainfall when the tropical Pacific is warmer than usual and the North Atlantic is colder than usual. This feature is consistent with the changing ENSO impact identified in previous studies and demonstrates how the ENSO teleconnection with the NAE climate at interannual timecales could be modulated by multidecadal changes in the SST. According to our results, the assumption of stationarity which is still common to many studies of ENSO teleconnections clearly has to

  15. ENSO influence on the North Atlantic European climate: a non-linear and non-stationary approach

    Science.gov (United States)

    López-Parages, Jorge; Rodríguez-Fonseca, Belén; Dommenget, Dietmar; Frauen, Claudia

    2015-12-01

    El Niño Southern Oscillation (ENSO) impact on the North Atlantic European sector (NAE) is still under discussion. Recent studies have found a non stationary feature of this teleconnection, suggesting an effective modulating role of the ocean mean state. Nevertheless, physical explanations about the underlying mechanisms have been little studied in the available literature. In addition, ENSO events show different SST spatial patterns, phases, and amplitudes, which can also influence on the related remote impacts. In view of all this, in the present study a set of partially coupled experiments have been performed with a global atmospheric general circulation model in which different SST ENSO patterns are superimposed over distinct Pacific and Atlantic SST mean states. These SST background conditions are constructed according to the observational difference between periods with a distinct impact of ENSO on the leading Euro-Mediterranean rainfall mode in late winter-early spring. Our results point to two distinct mechanisms associated with ENSO that can be modulated by the SST mean state: (1) the thermally driven direct circulation (Walker and Hadley cells) connecting the Atlantic and Pacific basins, and (2) the Rossby wave propagation from the tropical Pacific to the North Atlantic. The former elucidates that the positive NAO-like pattern usually related to La Niña events could be only valid for selected decades. The latter explains a reinforced signature of Eastern Pacific Niños on the Euro-Mediterranean rainfall when the tropical Pacific is warmer than usual and the North Atlantic is colder than usual. This feature is consistent with the changing ENSO impact identified in previous studies and demonstrates how the ENSO teleconnection with the NAE climate at interannual timecales could be modulated by multidecadal changes in the SST. According to our results, the assumption of stationarity which is still common to many studies of ENSO teleconnections clearly has to

  16. Inter-comparison studies between high-resolution HYCOM simulation and observational data: The South Atlantic and the Agulhas leakage system

    Science.gov (United States)

    Castellanos, P.; Campos, E. J. D.; Giddy, I.; Santis, W.

    2016-07-01

    Statistical analyses and model-data inter-comparisons are performed to evaluate the model's ability to reproduce the dynamics in the upper layers (region. The vertical structure is in agreement with in situ data, the model has lower skill when compared with PIRATA lower temperatures, and is able to capture the seasonal and annual variability in the tropical Atlantic. Furthermore, sensitive change until 2007 is clear in the vertical structure, at 4°N-38°W; 0°-35°W and 10°S-10°W, suggesting an important change in the stratification. The primary results concern a significant change in the decadal anomalies of the temperatures and salinity, which exhibit a warmer and saltier water in the southeastern Atlantic. Furthermore, linear trends found in the transport time-series in the North Brazil Current, and the South Equatorial Current were seen to correspond with increasing trends of the warmer water from the Agulhas Current into South Atlantic. The integrated transport during the period 1960-2010, shows an increase in westward changes in the large-scale circulation south of Africa are show in the negative trends indicate a widening of the "Agulhas gap" and increase in westward volume transport since 1980. It is therefore suggested that variability in the Agulhas System on the last two decades is affecting the dynamic in the South Atlantic, namely the temperature and the volume transport, reach the tropical region of the Atlantic.

  17. Atmospheric transmission of North Atlantic Heinrich events

    Science.gov (United States)

    Hostetler, S.W.; Clark, P.U.; Bartlein, P.J.; Mix, A.C.; Pisias, N.J.

    1999-01-01

    We model the response of the climate system during Heinrich event 2 (H2) by employing an atmospheric general circulation model, using boundary conditions based on the concept of a "canonical" Heinrich event. The canonical event is initialized with a full-height Laurentide ice sheet (LIS) and CLIMAP sea surface temperatures (SSTs), followed by lowering of the LIS, then warming of North Atlantic SSTs. Our modeled temperature and wind fields exhibit spatially variable responses over the Northern Hemisphere at each stage of the H2 event. In some regions the climatic responses are additive, whereas in other regions they cancel or are of opposite sign, suggesting that Heinrich event climatic variations may have left complex signatures in geologic records. We find variations in the tropical water balance and the mass balance of ice sheets, and implications for variations in terrestrial methane production from the contraction of northern permafrost regions and the expansion of tropical wetlands. Copyright 1999 by the American Geophysical Union.

  18. Effects of duty-cycled passive acoustic recordings on detecting the presence of beaked whales in the northwest Atlantic.

    Science.gov (United States)

    Stanistreet, Joy E; Nowacek, Douglas P; Read, Andrew J; Baumann-Pickering, Simone; Moors-Murphy, Hilary B; Van Parijs, Sofie M

    2016-07-01

    This study investigated the effects of using duty-cycled passive acoustic recordings to monitor the daily presence of beaked whale species at three locations in the northwest Atlantic. Continuous acoustic records were subsampled to simulate duty cycles of 50%, 25%, and 10% and cycle period durations from 10 to 60 min. Short, frequent listening periods were most effective for assessing the daily presence of beaked whales. Furthermore, subsampling at low duty cycles led to consistently greater underestimation of Mesoplodon species than either Cuvier's beaked whales or northern bottlenose whales, leading to a potential bias in estimation of relative species occurrence. PMID:27475208

  19. UK Atlantic Margin Environmental Survey: Introduction and overview of bathyal benthic ecology

    Science.gov (United States)

    Bett, Brian J.

    2001-05-01

    The recent expansion of the Oil and Gas Industry in to the deep waters of the UK Atlantic Frontier prompted the industry and its regulator to reappraise the needs and means of environmental monitoring. In concert, deep-sea academics, specialist contractors, the regulator and the Industry, through the Atlantic Frontier Environmental Network (AFEN), devised and implemented a large-scale environmental survey of the deep waters to the north and west of Scotland. The AFEN-funded survey was carried out during the summers of 1996 and 1998, and involved two steps; an initial sidescan sonar mapping of the survey areas, followed up with direct seabed investigations by coring and photography. This contribution deals with the latter step. Seabed samples were collected to assess sediment type, organic content, heavy metals, hydrocarbons and macrobenthos. Photographic and video observations were employed to provide both 'routine' seabed assessments and to investigate particular sidescan features of note. Although essentially intended as a 'baseline' environmental survey, anthropogenic impacts are already evident throughout the areas surveyed. Indications of the effects of deep-sea trawling were frequently encountered (seabed trawl marks and areas of disturbed sediments), being present in almost all of the areas studied and extending to water depths in excess of 1000 m. Evidence of localised contamination of the seabed by drilling muds was also detected, though background hydrocarbon contamination is predominantly of terrestrial origin or derived from shipping. The benthic ecology of the UK Atlantic Margin is dominated by the marked differences in the hydrography of the Faroe-Shetland Channel (FSC) and the Rockall Trough (RT). Comparatively warm North Atlantic Water is common to both areas; however, in the FSC, cold (subzero) waters occupy the deeper parts of the channel (>600 m). The extreme thermal gradient present on the West Shetland Slope has a substantial influence on the

  20. Absorption of /sup 45/Ca during the immersion of the aerial organs of Salicornia stricta

    Energy Technology Data Exchange (ETDEWEB)

    Langlois, J.; Vilquin, A.

    1971-04-01

    Immersion of the aerial organs of Salicornia stricta in a nutrient solution with added radioactive /sup 45/Ca resulted in the accumulation of /sup 45/Ca in the aerial organs. There was no accumulation when the roots were immersed in the nutrient solution. Absorption of minerals by the stems and leaves of Salicornia during periodic submersions in the brackish water surrounding the plants, is therefore possible. 17 references, 1 figure, 1 table.

  1. Atlantic hurricane surge response to geoengineering.

    Science.gov (United States)

    Moore, John C; Grinsted, Aslak; Guo, Xiaoran; Yu, Xiaoyong; Jevrejeva, Svetlana; Rinke, Annette; Cui, Xuefeng; Kravitz, Ben; Lenton, Andrew; Watanabe, Shingo; Ji, Duoying

    2015-11-10

    Devastating floods due to Atlantic hurricanes are relatively rare events. However, the frequency of the most intense storms is likely to increase with rises in sea surface temperatures. Geoengineering by stratospheric sulfate aerosol injection cools the tropics relative to the polar regions, including the hurricane Main Development Region in the Atlantic, suggesting that geoengineering may mitigate hurricanes. We examine this hypothesis using eight earth system model simulations of climate under the Geoengineering Model Intercomparison Project (GeoMIP) G3 and G4 schemes that use stratospheric aerosols to reduce the radiative forcing under the Representative Concentration Pathway (RCP) 4.5 scenario. Global mean temperature increases are greatly ameliorated by geoengineering, and tropical temperature increases are at most half of those temperature increases in the RCP4.5. However, sulfate injection would have to double (to nearly 10 teragrams of SO2 per year) between 2020 and 2070 to balance the RCP4.5, approximately the equivalent of a 1991 Pinatubo eruption every 2 y, with consequent implications for stratospheric ozone. We project changes in storm frequencies using a temperature-dependent generalized extreme value statistical model calibrated by historical storm surges and observed temperatures since 1923. The number of storm surge events as big as the one caused by the 2005 Katrina hurricane are reduced by about 50% compared with no geoengineering, but this reduction is only marginally statistically significant. Nevertheless, when sea level rise differences in 2070 between the RCP4.5 and geoengineering are factored into coastal flood risk, we find that expected flood levels are reduced by about 40 cm for 5-y events and about halved for 50-y surges.

  2. Atlantic hurricane surge response to geoengineering

    Energy Technology Data Exchange (ETDEWEB)

    Moore, John C.; Grinsted, Aslak; Guo, Xiaoran; Yu, Xiaoyong; Jevrejeva, Svetlana; Rinke, Annette; Cui, Xuefeng; Kravitz, Ben; Lenton, Andrew; Watanabe, Shingo; Ji, Duoying

    2015-10-26

    Devastating Atlantic hurricanes are relatively rare events. However their intensity and frequency in a warming world may rapidly increase by a factor of 2-7 for each degree of increase in mean global temperature. Geoengineering by stratospheric sulphate aerosol injection cools the tropics relative to the polar regions, including the hurricane main development region in the Atlantic, suggesting that geoengineering may be an effective method of controlling hurricanes. We examine this hypothesis using 8 Earth System Model simulations of climate under the GeoMIP G3 and G4 schemes that use stratospheric aerosols to reduce the radiative forcing under the RCP4.5 scenario. Global mean temperature increases are greatly ameliorated by geoengineering, and tropical temperature increases are at most half of those in RCP4.5, but sulphate injection would have to double between 2020 and 2070 to balance RCP 4.5 to nearly 10 Tg SO2 yr-1, with consequent implications for damage to stratospheric ozone. We project changes in storm frequencies using a temperature-dependent Generalized Extreme Value statistical model calibrated by historical storm surges from 1923 and observed temperatures. The numbers of storm surge events as big as the one that caused the 2005 Katrina hurricane are reduced by about 50% compared with no geoengineering, but this is only marginally statistically significant. However, when sea level rise differences at 2070 between RCP4.5 and geoengineering are factored in to coastal flood risk, we find that expected flood levels are reduced by about 40 cm for 5 year events and perhaps halved for 50 year surges.

  3. Atlantic hurricane surge response to geoengineering.

    Science.gov (United States)

    Moore, John C; Grinsted, Aslak; Guo, Xiaoran; Yu, Xiaoyong; Jevrejeva, Svetlana; Rinke, Annette; Cui, Xuefeng; Kravitz, Ben; Lenton, Andrew; Watanabe, Shingo; Ji, Duoying

    2015-11-10

    Devastating floods due to Atlantic hurricanes are relatively rare events. However, the frequency of the most intense storms is likely to increase with rises in sea surface temperatures. Geoengineering by stratospheric sulfate aerosol injection cools the tropics relative to the polar regions, including the hurricane Main Development Region in the Atlantic, suggesting that geoengineering may mitigate hurricanes. We examine this hypothesis using eight earth system model simulations of climate under the Geoengineering Model Intercomparison Project (GeoMIP) G3 and G4 schemes that use stratospheric aerosols to reduce the radiative forcing under the Representative Concentration Pathway (RCP) 4.5 scenario. Global mean temperature increases are greatly ameliorated by geoengineering, and tropical temperature increases are at most half of those temperature increases in the RCP4.5. However, sulfate injection would have to double (to nearly 10 teragrams of SO2 per year) between 2020 and 2070 to balance the RCP4.5, approximately the equivalent of a 1991 Pinatubo eruption every 2 y, with consequent implications for stratospheric ozone. We project changes in storm frequencies using a temperature-dependent generalized extreme value statistical model calibrated by historical storm surges and observed temperatures since 1923. The number of storm surge events as big as the one caused by the 2005 Katrina hurricane are reduced by about 50% compared with no geoengineering, but this reduction is only marginally statistically significant. Nevertheless, when sea level rise differences in 2070 between the RCP4.5 and geoengineering are factored into coastal flood risk, we find that expected flood levels are reduced by about 40 cm for 5-y events and about halved for 50-y surges. PMID:26504210

  4. Polysheroidal periodic functions

    International Nuclear Information System (INIS)

    Separation of variables in the Helmholtz N-dimensional (N≥4) equation in polyspheroidal coordinate systems leads to the necessity of solving equations going over into equations for polyspheroidal periodic functions used for solving the two-centre problem in quantum mechanics, the three-body problem with Coulomb interaction, etc. For these functions the expansions are derived in terms of the Jacobi polynomials and Bessel functions. Their basic properties, asymptotics are considered. The algorithm of their computer calculations is developed. The results of numerical calculations are given

  5. On occult period maps

    CERN Document Server

    Kudla, Stephen

    2012-01-01

    We consider the "occult" period maps into ball quotients which exist for the moduli spaces of cubic surfaces, cubic threefolds, non-hyperelliptic curves of genus three and four. These were constructed in the work of Allcock/Carlson/Toledo, Looijenga/Swierstra, and Kondo. We interpret these maps as morphisms into moduli spaces of polarized abelian varieties of Picard type, and show that these morphisms, whose initial construction is transcendental, are defined over the natural field of definition of the spaces involved. This paper is extracted from section 15 of our paper arXiv:0912.3758, and differs from it only in some points of exposition.

  6. The postanesthetic period. Complications.

    Science.gov (United States)

    Malamed, S F

    1987-01-01

    Postanesthetic complications can occur even in the best of circumstances. Proper preparation of the staff, aggressive monitoring of the recovering patient, and early recognition and management of the complications are essential if the outcome is to be successful. In reviewing postanesthetic complications, two factors are present in the overwhelming majority of situations--hypoxia and hypercarbia--often the direct result of inadequate monitoring during the postanesthetic period. The anesthetic procedure is not over once the anesthetic agents are discontinued. The skillful anesthetist is aware of the possibilities of postoperative complications and prevents problems by employing enhanced monitoring techniques during the recovery phase.

  7. Scattering of periodic solitons

    CERN Document Server

    Cova, R J

    2003-01-01

    With the help of numerical simulations we study N-soliton scattering (N=3,4) in the (2+1)-dimensional CP^1 model with periodic boundary conditions. When the solitons are scattered from symmetrical configurations the scattering angles observed agree with the earlier \\pi/N predictions based on the model on R_2 with standard boundary conditions. When the boundary conditions are not symmetric the angles are different from \\pi/N. We present an explanation of our observed patterns based on a properly formulated geodesic approximation.

  8. Spatial and temporal patterns of organic contaminants in wet precipitation in Atlantic Canada

    International Nuclear Information System (INIS)

    Wet precipitation samples were collected on a monthly basis from three locations in Atlantic Canada for the period 1980-1989 and analyzed for organochlorine pesticides, total polychlorinated biphenyls (PCBs), chlorinated benzenes, and polynuclear aromatic hydrocarbons (PAHs). The compounds most commonly detected included the pesticide lindane (γ-HCH) and its decomposition product α-HCH, fluoranthene, benzo[a]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, and PCBs. Statistical analysis of α-HCH and γ-HCH data indicated a significant decrease in concentration of these compounds after 1983, probably the result of curtailing the agricultural use of lindane in North America and on other continents. Seasonal patterns were observed with maximum concentrations/loadings occurring during the spring and fall. Fluoranthene was the dominant PAH compound and was detected in almost every sample. Fluoranthene and other PAHs were shown to follow seasonal patterns, with increasing concentrations during the colder months of the year (December to April). Spatial influences were also observed, indicating both localized and long-range atmospheric source inputs. Abnormally high annual mean concentrations of PCBs ranging between nondetectable levels and 0.220 μ/l were measured during the 1981-1986 period at the Prince Edward Island station. Spatial variations for PCBs in the Atlantic Region were significant and attributed in part to localized source inputs. Seasonal patterns similar to the PAHs were also observed. Concentrations dropped to nondetectable levels after 1984 at all sites with the exception of a few sporadic observations

  9. Measurements of natural 41Ca concentrations

    International Nuclear Information System (INIS)

    Atomic mass spectroscopic examinations on 41Ca were carried out in the UNILAC accelerator. A sensitivity of about 10-15 was achieved. This would allow the measurement of present natural 41Ca concentrations as soon as the problem of the transmission determination is solved. In this respect suggestions were worked out and their feasibility discussed. The detection of 41Ca-ions is especially free of background when high UNILAC-energies are applied. An estimation showed a background level corresponding with a 41Ca concentration of less then 10-17 referred to 40Ca. Besides an independent concept for the electromagnetic concentration of 41Ca with variable concentration factors was developed. After being concentrated up to 50 respectively 25 times the initial concentration in the GSI mass separator, the 41Ca concentration of three recent deer bones found in the Odenwald was measured by atomic mass spectroscopy in the 14UD-Pelletron Tandem in Rehovot (Israel). The measured 41Ca concentrations ranged between 10-14 to 10-13 with consideration of the concentration factor. A theoretical study of the 41Ca production in the earth's surface based on cosmic radiation illustrates the influence of trace elements on the neutron flux and thus on the 41Ca production. This influence might be a possible explanation for the observed amplitude of variation of the 41Ca concentration in recent bones which are of decisive importance for the feasibility of 41Ca-related dating. In this work a method is suggested that does not depend on the amplitude of variation mentioned above and which would allow the determination of the erosion rate of rocks by its 41Ca concentrations. (orig./HP)

  10. The impact of North Atlantic sea surface temperature errors on the simulation of North Atlantic European region climate

    OpenAIRE

    Keeley, Sarah; Sutton, Rowan; Shaffrey, Len

    2012-01-01

    Current state-of-the-art climate models fail to capture accurately the path of the Gulf Stream and North Atlantic Current. This leads to a warm bias near the North American coast, where the modelled Gulf Stream separates from the coast further north, and a cold anomaly to the east of the Grand Banks of Newfoundland, where the North Atlantic Current remains too zonal in this region. Using an atmosphere-only model forced with the sea surface temperature (SST) biases in the North Atlantic, we...

  11. Involvement of Ca2+/CaM in the signal transduction of acetylcholine regulating stomatal movement

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    It has been known that the neurotransmitter acetylcholine (ACh) also exists in plants and is able to regulate the movement of stomata. In another aspect, Ca2+/CaM as the second messengers have a critical role of signal transduction in stomatal guard-cell. Here we showed that Ca2+/CaM were also involved in theACh regulated stomatal movement. In the medium containing Ca2+, the Ca2+ channel blockers (NIF and Ver) and CaM inhibitors (TFP and W7) could neutralize the ACh induced stomatal opening, however, they are ineffective in the medium containing K+. Those results indicated that Ca2+/CaM were involved in the signal transduction pathway of ACh regulating stomatal movement.

  12. Decadal predictions of the North Atlantic CO2 uptake.

    Science.gov (United States)

    Li, Hongmei; Ilyina, Tatiana; Müller, Wolfgang A; Sienz, Frank

    2016-01-01

    As a major CO2 sink, the North Atlantic, especially its subpolar gyre region, is essential for the global carbon cycle. Decadal fluctuations of CO2 uptake in the North Atlantic subpolar gyre region are associated with the evolution of the North Atlantic Oscillation, the Atlantic meridional overturning circulation, ocean mixing and sea surface temperature anomalies. While variations in the physical state of the ocean can be predicted several years in advance by initialization of Earth system models, predictability of CO2 uptake has remained unexplored. Here we investigate the predictability of CO2 uptake variations by initialization of the MPI-ESM decadal prediction system. We find large multi-year variability in oceanic CO2 uptake and demonstrate that its potential predictive skill in the western subpolar gyre region is up to 4-7 years. The predictive skill is mainly maintained in winter and is attributed to the improved physical state of the ocean. PMID:27026490

  13. Science and Society: The Third Dimension of the Atlantic Alliance.

    Science.gov (United States)

    Sudarskis, Michel

    1983-01-01

    Discusses North Atlantic Treaty Organization (NATO) activities related to science and society. NATO Scientific Exchanges Programme; pilot studies (pollution control, natural resources, health and technological risks, quality of life, and planning); and cultural exchanges are among the areas considered. (JN)

  14. Inventory of Atlantic White Cedar Remnant Stands in North Carolina.

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This inventory was commissioned by the U.S. Air Force to identify the location and condition of extant remnant Atlantic white cedar groves and stands in North...

  15. Research Ship Atlantic Explorer Underway Meteorological Data, Quality Controlled

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Research Ship Atlantic Explorer Underway Meteorological Data (delayed ~10 days for quality control) are from the Shipboard Automated Meteorological and...

  16. Subcropping Geology for the Mid-Atlantic Coastal Plain

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Subcropping geology for the Mid-Atlantic Coastal Plain was compiled and interpreted from available published sources. Formation contacts were interpolated across...

  17. Outer Continental Shelf Lease Blocks - Atlantic Region NAD83

    Data.gov (United States)

    Bureau of Ocean Energy Management, Department of the Interior — This data set contains OCS block outlines in ArcGIS shape file format for the BOEM Atlantic Region. OCS blocks are used to define small geographic areas within an...

  18. Outer Continental Shelf Official Protraction Diagrams - Atlantic Region NAD 83

    Data.gov (United States)

    Bureau of Ocean Energy Management, Department of the Interior — This data set contains Official Protraction Diagram (OPD) outlines in ESRI shapefile format. Atlantic Region OPDs are approximately 2 degrees wide by one degree...

  19. Physiography for the Mid-Atlantic Coastal Plain

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Physiography for the Mid-Atlantic Coastal Plain was constructed by standardizing and extrapolating previous physiographic interpretations for areas within and...

  20. Economic Assessment of the Atlantic Coast Horseshoe Crab Fishery

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — In this report, Industrial Economics, Incorporated (lEc) provides an assessment of the economic value of the Atlantic Coast horseshoe crab fishery. We accomplish...

  1. Atlantic Sharpnose and Blacknose Shark Congressional Supplemental Sampling

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Life history data were collected from Atlantic sharpnose and blacknose sharks during the Congressional Supplemental Program during 2011. Data collected include...

  2. South Atlantic Seasonal and/or Area Closures GIS data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data represent the geographic area described in Title 50 CFR Part 622 Fisheries of the Caribbean, Gulf of Mexico, and South Atlantic, Subpart A - General...

  3. Transport of salt and freshwater in the Atlantic Subpolar Gyre

    Science.gov (United States)

    Born, Andreas; Stocker, Thomas F.; Sandø, Anne Britt

    2016-09-01

    Transport of salt in the Irminger Current, the northern branch of the Atlantic Subpolar Gyre coupling the eastern and western subpolar North Atlantic, plays an important role for climate variability across a wide range of time scales. High-resolution ocean modeling and observations indicate that salinities in the eastern subpolar North Atlantic decrease with enhanced circulation of the North Atlantic subpolar gyre (SPG). This has led to the perception that a stronger SPG also transports less salt westward. In this study, we analyze a regional ocean model and a comprehensive global coupled climate model, and show that a stronger SPG transports more salt in the Irminger Current irrespective of lower salinities in its source region. The additional salt converges in the Labrador Sea and the Irminger Basin by eddy transports, increases surface salinity in the western SPG, and favors more intense deep convection. This is part of a positive feedback mechanism with potentially large implications for climate variability and predictability.

  4. Meridional coherence and divergence of the Atlantic Meridional Overturning Circulation (AMOC)

    Science.gov (United States)

    Kanzow, T.; Lankhorst, M.; Frajka-Williams, E.; Send, U.; Cunningham, S. A.; Bingham, R.; Karstensen, J.; Hughes, C. W.

    2012-04-01

    The AMOC is responsible for the meridional transport of heat on climate relevant timescales. Numerical model studies suggest, that the AMOC varies on broad range of periods: Wind forcing dominates local and intraseasonal variability; Buoyancy forcing is important at longer periods and sets - at least the mean strength - of a meridionally coherent AMOC. We shall present contemporaneous observations targeting AMOC fluctuations for the period 2000 to 2010. Three continuous data sets from 16°N, 26°N and 40°N are available. Continuous mooring-based density observations of the deep southward transport of North Atlantic Deep Water in the western basin are available since the year 2000 at 16°N in the framework of the MOVE experiment (operated by SIO, San Diego, USA). From 2006 the western basin transports are extended to the eastern basin using data from the TENATSO mooring near Cape Verde. This enables us to compute NADW transports integrated across almost the entire zonal width of the Atlantic at 16°N. From 2004 the RAPID / MOCHA (NOC, UK / RSMAS & AOML, USA) a purposefully designed monitoring array has been monitoring the strength of the AMOC (both the northward transport of warm water and cold NADW return flow) at 26°N To put the decade-long observations at 16°N and 26°N into a long-term perspective, we construct a 146 year-long index of changes of the AMOC near 40°N based on tide gauge records along the US east coast (which goes back in time with interruptions to the year 1856). We present evidence for the occurrence of coherent changes of the AMOC between 16°N and 26°N, suggesting that AMOC anomalies with meridional scales larger than 1000 km are observed. We find evidence for periods of pronounced divergence in NADW transports between 16°N and 26°N. Isolating different transport contributions of the AMOC signal at both latitudes we trace the origin of coherent and divergent events. Extreme low AMOC values (observation period 2004 to 2010) were observed

  5. Atlantic Warm Pool Trigger for the Younger Dryas Climate Event

    Science.gov (United States)

    Abdul, N. A.; Mortlock, R. A.; Wright, J. D.; Fairbanks, R. G.; Teneva, L. T.

    2011-12-01

    There is growing evidence that variability in the size and heat content of the tropical Atlantic Warm Pool impacts circum-North Atlantic climate via the Atlantic Multi-decadal Oscillation mode (Wang et al., 2008). The Atlantic Warm Pool spans the Gulf of Mexico, Caribbean Sea and the western tropical North Atlantic. Barbados is located near the center of the tropical Atlantic Warm Pool and coupled ocean models suggest that Barbados remains near the center of the tropical Atlantic Warm Pool under varying wind stress simulations. Measurements of the oxygen isotope paleothermometer in Acropora palmata coral species recovered from cores offshore Barbados, show a 3oC monotonic decrease in sea surface temperature from 13106 ± 83 to 12744 ± 61 years before present (errors given as 2 sigma). This interval corresponds to a sea level rise from 71.4 meters to 67.1 meters below present levels at Barbados. The 3oC temperature decrease is captured in eight A. palmata specimens that are in stratigraphic sequence, 230Th/234U dated, and analyzed for oxygen isotopes. All measurements are replicated. We are confident that this is the warm pool equivalent of the Younger Dryas climate event. The initiation of this temperature drop in the Atlantic Warm Pool predates the Younger Dryas start in Greenland ice cores, reported to start at 12896 ± 138 years (relative to AD 2000) (Rasmussen et al., 2006), while few other Younger Dryas climate records are dated with similar accuracy to make the comparison. Rasmussen, S.O., Andersen, K.K., Svensson, A.M., Steffensen, J.P., Vinther, B.M., Clausen, H.B., Siggaard-Andersen, M.L., Johnsen, S.J., Larsen, L.B., Dahl-Jensen, D., Bigler, M., Röthlisberger, R., Fischer, H., Goto-Azuma, K., Hansson, M.E., and Ruth, U., 2006, A new Greenland ice core chronology for the last glacial termination: J. Geophys. Res., v. 111, p. D06102. Wang, C., Lee, S.-K., and Enfield, D.B., 2008, Atlantic Warm Pool acting as a link between Atlantic Multidecadal

  6. Dissection of local Ca(2+) signals inside cytosol by ER-targeted Ca(2+) indicator.

    Science.gov (United States)

    Niwa, Fumihiro; Sakuragi, Shigeo; Kobayashi, Ayana; Takagi, Shin; Oda, Yoichi; Bannai, Hiroko; Mikoshiba, Katsuhiko

    2016-10-01

    Calcium (Ca(2+)) is a versatile intracellular second messenger that operates in various signaling pathways leading to multiple biological outputs. The diversity of spatiotemporal patterns of Ca(2+) signals, generated by the coordination of Ca(2+) influx from the extracellular space and Ca(2+) release from the intracellular Ca(2+) store the endoplasmic reticulum (ER), is considered to underlie the diversity of biological outputs caused by a single signaling molecule. However, such Ca(2+) signaling diversity has not been well described because of technical limitations. Here, we describe a new method to report Ca(2+) signals at subcellular resolution. We report that OER-GCaMP6f, a genetically encoded Ca(2+) indicator (GECI) targeted to the outer ER membrane, can monitor Ca(2+) release from the ER at higher spatiotemporal resolution than conventional GCaMP6f. OER-GCaMP6f was used for in vivo Ca(2+) imaging of C. elegans. We also found that the spontaneous Ca(2+) elevation in cultured astrocytes reported by OER-GCaMP6f showed a distinct spatiotemporal pattern from that monitored by plasma membrane-targeted GCaMP6f (Lck-GCaMP6f); less frequent Ca(2+) signal was detected by OER-GCaMP6f, in spite of the fact that Ca(2+) release from the ER plays important roles in astrocytes. These findings suggest that targeting of GECIs to the ER outer membrane enables sensitive detection of Ca(2+) release from the ER at subcellular resolution, avoiding the diffusion of GECI and Ca(2+). Our results indicate that Ca(2+) imaging with OER-GCaMP6f in combination with Lck-GCaMP6f can contribute to describing the diversity of Ca(2+) signals, by enabling dissection of Ca(2+) signals at subcellular resolution.

  7. Projected Atlantic hurricane surge threat from rising temperatures

    OpenAIRE

    Grinsted, Aslak; Moore, John C.; Jevrejeva, Svetlana

    2013-01-01

    Detection and attribution of past changes in cyclone activity are hampered by biased cyclone records due to changes in observational capabilities. Here, we relate a homogeneous record of Atlantic tropical cyclone activity based on storm surge statistics from tide gauges to changes in global temperature patterns. We examine 10 competing hypotheses using nonstationary generalized extreme value analysis with different predictors (North Atlantic Oscillation, Southern Oscillation, Pacific Decadal ...

  8. Operational numerical prediction of rapid cyclogenesis over the North Atlantic

    OpenAIRE

    GADD, A. J.; HALL, C. D.; KRUZE, R. E.

    2011-01-01

    The current generation of operational numerical weather prediction models has shown considerable skill in handling cyclogenesis. This paper assesses the accuracy of forecasts of rapid cyclogenesis over the North Atlantic from the operational NWP system at Bracknell and attempts to isolate the factors relevant to successful prediction. Illustrative material is drawn in particular from the case of the record low pressure centre that developed over the North Atlantic on 14 December 1986.DOI: 10....

  9. Population genetic studies in Northeastern Atlantic minke whales

    OpenAIRE

    Berube, M.; Skaug, Hans Julius; Andersen, Liselotte W.; Haug, Tore; Øien, Nils

    2007-01-01

    Minke whales are the most abundance species of baleen whales in the North Atlantic. As part of current management of minke whales in Norwegian and adjacent waters, a DNA-register have been established. The register ensures that samples are taken of each animal caught under the Norwegian catch quota, and that a DNA-profile is established and stored in a database from each individual whale. Previous studies have indicated that genetic population sub-structure exists within the North Atlantic, b...

  10. Tropical versus high latitude freshwater influence on the Atlantic circulation

    OpenAIRE

    Goelzer, H.; J. Mignot; Levermann, A; Rahmstorf, S.

    2006-01-01

    We investigate the model sensitivity of the Atlantic meridional overturning circulation (AMOC) to anomalous freshwater flux in the tropical and northern Atlantic. Forcing in both locations leads to the same qualitative response: a positive freshwater anomaly induces a weakening of the AMOC and a negative freshwater anomaly strengthens the AMOC. Strong differences arise in the temporal characteristics and amplitude of the response. The advection of the tropical anomaly up to the deep water for...

  11. Many Seasons Gone: Memory, History, and the Atlantic Slave Trade

    OpenAIRE

    Ted Maris-Wolf

    2009-01-01

    [First paragraph] African Voices of the Atlantic Slave Trade: Beyond the Silence and the Shame. Anne C. Bailey. Boston: Beacon Press, 2005. 289 pp. (Cloth US $ 26.00) Lose Your Mother: A Journey along the Atlantic Slave Route. Saidiya Hartman. New York: Farrar, Straus and Giroux, 2007. xi + 270 pp. (Cloth US $ 25.00) In Two Thousand Seasons, the great Ghanaian novelist Ayi Kwei Armah describes the effects of centuries of European exploitation and violence in Africa and th...

  12. A Study of Mesoscale Gravity Waves over the North Atlantic with Satellite Observations and a Mesoscale Model

    Science.gov (United States)

    Wu, Dong L.; Zhang, Fuqing

    2004-01-01

    Satellite microwave data are used to study gravity wave properties and variabilities over the northeastern United States and the North Atlantic in the December-January periods. The gravity waves in this region, found in many winters, can reach the stratopause with growing amplitude. The Advanced Microwave Sounding Unit-A (AMSU-A) observations show that the wave occurrences are correlated well with the intensity and location of the tropospheric baroclinic jet front systems. To further investigate the cause(s) and properties of the North Atlantic gravity waves, we focus on a series of wave events during 19-21 January 2003 and compare AMSU-A observations to simulations from a mesoscale model (MM5). The simulated gravity waves compare qualitatively well with the satellite observations in terms of wave structures, timing, and overall morphology. Excitation mechanisms of these large-amplitude waves in the troposphere are complex and subject to further investigations.

  13. Effects of chronic produced water exposure on the expression of some immune-related genes of juvenile Atlantic cod

    International Nuclear Information System (INIS)

    This study assessed the impacts of exposure to processed water produced by offshore oil operators on immune-related genes of juvenile Atlantic cod exposed to processed water for a period of 22 weeks. The study investigated the influence of processed water concentrations on growth parameters; food consumption; plasma cortisol; respiratory burst activity (RB); and mRNA expression. The study showed that the RB of circulating leukocytes was significantly elevated. Significant up-regulation of the mRNA expression of microglobulin, immunoglobulin light chain, and interleukins was observed in some fish. The down-regulation of the interferon stimulated gene was also observed. The study indicated that chronic exposure to significant amounts of processed water causes modulations of the immune system of juvenile Atlantic cod.

  14. Near seafloor bioluminescence, macrozooplankton and macroparticles at the Mid-Atlantic Ridge

    Science.gov (United States)

    Craig, Jessica; Youngbluth, Marsh; Jamieson, Alan J.; Priede, Imants G.

    2015-04-01

    The benthic boundary layer is a region often perceived to be high in faunal abundance and biomass. In this study, we investigated the distribution of near seafloor bioluminescent zooplankton (BL), macrozooplankton (>1 cm) and macroparticles (>430 μm) at the Northern Mid-Atlantic Ridge at ca. 2500 m depth. At sites south of 52°N, the Charlie Gibbs Fracture Zone, BL density increased weakly towards the seafloor. This trend was driven by small bioluminescent crustaceans, comprising ca. 90% of the total BL density. Macroparticle density was coherent with BL density, exhibiting a small increase towards the seafloor. Appendicularians (animals as well as occupied and discarded houses) were the most abundant macrozooplankton, and the only group to show a significant increase in density towards the seafloor. The absence of pronounced increases in BL and macroparticle density, and no increase in macrozooplankton (except appendicularians), towards the seafloor do not support the conventional view of high concentrations of particulate organic matter and zooplankton biomass in the benthic boundary layer relative to overlying waters.

  15. Reduced interdecadal variability of Atlantic Meridional Overturning Circulation under global warming.

    Science.gov (United States)

    Cheng, Jun; Liu, Zhengyu; Zhang, Shaoqing; Liu, Wei; Dong, Lina; Liu, Peng; Li, Hongli

    2016-03-22

    Interdecadal variability of the Atlantic Meridional Overturning Circulation (AMOC-IV) plays an important role in climate variation and has significant societal impacts. Past climate reconstruction indicates that AMOC-IV has likely undergone significant changes. Despite some previous studies, responses of AMOC-IV to global warming remain unclear, in particular regarding its amplitude and time scale. In this study, we analyze the responses of AMOC-IV under various scenarios of future global warming in multiple models and find that AMOC-IV becomes weaker and shorter with enhanced global warming. From the present climate condition to the strongest future warming scenario, on average, the major period of AMOC-IV is shortened from ∼50 y to ∼20 y, and the amplitude is reduced by ∼60%. These reductions in period and amplitude of AMOC-IV are suggested to be associated with increased oceanic stratification under global warming and, in turn, the speedup of oceanic baroclinic Rossby waves.

  16. Predicting Atlantic seasonal hurricane activity using outgoing longwave radiation over Africa

    Science.gov (United States)

    Karnauskas, Kristopher B.; Li, Laifang

    2016-07-01

    Seasonal hurricane activity is a function of the amount of initial disturbances (e.g., easterly waves) and the background environment in which they develop into tropical storms (i.e., the main development region). Focusing on the former, a set of indices based solely upon the meridional structure of satellite-derived outgoing longwave radiation (OLR) over the African continent are shown to be capable of predicting Atlantic seasonal hurricane activity with very high rates of success. Predictions of named storms based on the July OLR field and trained only on the time period prior to the year being predicted yield a success rate of 87%, compared to the success rate of NOAA's August outlooks of 53% over the same period and with the same average uncertainty range (±2). The resulting OLR indices are statistically robust, highly detectable, physically linked to the predictand, and may account for longer-term observed trends.

  17. Wet periods in northeastern Brazil over the past 210 kyr linked to distant climate anomalies.

    Science.gov (United States)

    Wang, Xianfeng; Auler, Augusto S; Edwards, R Lawrence; Cheng, Hai; Cristalli, Patricia S; Smart, Peter L; Richards, David A; Shen, Chuan-Chou

    2004-12-01

    The tropics are the main source of the atmosphere's sensible and latent heat, and water vapour, and are therefore important for reconstructions of past climate. But long, accurately dated records of southern tropical palaeoclimate, which would allow the establishment of climatic connections to distant regions, have not been available. Here we present a 210,000-year (210-kyr) record of wet periods in tropical northeastern Brazil--a region that is currently semi-arid. The record is obtained from speleothems and travertine deposits that are accurately dated using the U/Th method. We find wet periods that are synchronous with periods of weak East Asian summer monsoons, cold periods in Greenland, Heinrich events in the North Atlantic and periods of decreased river runoff to the Cariaco basin. We infer that the wet periods may be explained with a southward displacement of the Intertropical Convergence Zone. This widespread synchroneity of climate anomalies suggests a relatively rapid global reorganization of the ocean-atmosphere system. We conclude that the wet periods probably affected rainforest distribution, as plant fossils show that forest expansion occurred during these intermittent wet intervals, and opened a forest corridor between the Amazonian and Atlantic rainforests. PMID:15592409

  18. Temporal and spatial characteristics of sea surface height variability in the North Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    D. Cromwell

    2006-01-01

    Full Text Available We investigate the spatial and temporal variability of sea surface height (SSH in the North Atlantic basin using satellite altimeter data from October 1992–January 2004. Our primary aim is to provide a detailed description of such variability, including that associated with propagating signals. We also investigate possible correlations between SSH variability and atmospheric pressure changes as represented by climate indices. We first investigate interannual SSH variations by deriving the complex empirical orthogonal functions (CEOFs of altimeter data lowpass-filtered at 18 months. We determine the spatial structure of the leading four modes (both in amplitude and phase and also the associated principal component (PC time series. Using wavelet analysis we derive the time-varying spectral density of the PCs, revealing when particular modes were strongest between 1992–2004. The spatial pattern of the leading CEOF, comprising 30% of the total variability, displays a 5-year periodicity in phase; signal propagation is particularly marked in the Labrador Sea. The second mode, with a dominant 3-year signal, has strong variability in the eastern basin. Secondly, we focus on the Azores subtropical frontal zone. The leading mode (35% is strong in the south and east of this region with strong variations at 3- and 5-year periods. The second mode (21% has a near-zonal band of low variance between  22°–27° N, sandwiched between two regions of high variance. Thirdly, we lowpass filter the altimeter data at a cutoff of 30 days, instead of 18 months, in order to retain signals associated with propagating baroclinic Rossby waves and/or eddies. The leading mode is the annual steric signal, around 46% of the SSH variability. The third and fourth CEOFs,  11% of the remaining variability, are associated with westward propagation which is particularly dominant in a "waveband" between 32°–36° N. For all three cases considered above, no significant cross

  19. Periods and Superstring Amplitudes

    CERN Document Server

    Stieberger, S

    2016-01-01

    Scattering amplitudes which describe the interaction of physical states play an important role in determining physical observables. In string theory the physical states are given by vibrations of open and closed strings and their interactions are described (at the leading order in perturbation theory) by a world-sheet given by the topology of a disk or sphere, respectively. Formally, for scattering of N strings this leads to N-3-dimensional iterated real integrals along the compactified real axis or N-3-dimensional complex sphere integrals, respectively. As a consequence the physical observables are described by periods on M_{0,N} - the moduli space of Riemann spheres of N ordered marked points. The mathematical structure of these string amplitudes share many recent advances in arithmetic algebraic geometry and number theory like multiple zeta values, single-valued multiple zeta values, Drinfeld, Deligne associators, Hopf algebra and Lie algebra structures related to Grothendiecks Galois theory. We review the...

  20. Reorganization of the North Atlantic Oscillation during early Holocene deglaciation

    Science.gov (United States)

    Wassenburg, Jasper A.; Dietrich, Stephan; Fietzke, Jan; Fohlmeister, Jens; Jochum, Klaus Peter; Scholz, Denis; Richter, Detlev K.; Sabaoui, Abdellah; Spötl, Christoph; Lohmann, Gerrit; Andreae, Meinrat O.; Immenhauser, Adrian

    2016-08-01

    The North Atlantic Oscillation is the dominant atmospheric pressure mode in the North Atlantic region and affects winter temperature and precipitation in the Mediterranean, northwest Europe, Greenland, and Asia. The index that describes the sea-level pressure difference between Iceland and the Azores is correlated with a dipole precipitation pattern over northwest Europe and northwest Africa. How the North Atlantic Oscillation will develop as the Greenland ice sheet melts is unclear. A potential past analogue is the early Holocene, during which melting ice sheets around the North Atlantic freshened surface waters, affecting the strength of the meridional overturning circulation. Here we present a Holocene rainfall record from northwest Africa based on speleothem δ18O and compare it against a speleothem-based rainfall record from Europe. The two records are positively correlated during the early Holocene, followed by a shift to an anti-correlation, similar to the modern record, during the mid-Holocene. On the basis of our simulations with an Earth system model, we suggest the shift to the anti-correlation reflects a large-scale atmospheric and oceanic reorganization in response to the demise of the Laurentide ice sheet and a strong reduction of meltwater flux to the North Atlantic, pointing to a potential sensitivity of the North Atlantic Oscillation to the melting of ice sheets.