Late Quaternary Palaeoceanographic Changes in Sea Surface Conditions in the Tropical Atlantic

Science.gov (United States)

Fischel, Andrea; Seidenkrantz, Marit-Solveig; Kuijpers, Antoon; Nürnberg, Dirk

2013-04-01

Palaeoceanographic changes and the variability in surface water mass hydrography are reconstructed in order to track tropical ocean and climate variability and inter-hemispheric heat exchange through the last 42,000 year BP. Our studies are based on the relative abundance of planktonic foraminifera combined with sea surface temperature approximation based Mg/Ca measurements, XRF scanning and stable oxygen isotope analyses in a 5 m long gravity core Ga307-Win-12GC (17°50.80N, 64°48.7290W), retrieved in the Virgin Island Basin in approx. 3,960 m water depth. The Virgin Island Basin is the deepest part of the Anegada-Jungfern Passage in the northeast Caribbean, one of the most important pathways for water mass exchange between the Central Atlantic and the Caribbean Sea. Due to its bathymetry surface waters as well as deep water mass strata from the northern and southern hemisphere enter the basin, comprising Caribbean Surface Water (CSW), Antarctic Intermediate Water (AAIW), Atlantic Intermediate Water (AIW) and North Atlantic Deep Water (NADW). The planktonic foraminiferal assemblage suggests rather stable sea-surface conditions during the Holocene in the NE Caribbean. However, major changes in the hydrographic setting could be identified within the glacial period. During the glacial period, clear millennial-scale variability in sea-surface temperature and productivity are present. Fluctuations in the relative abundance of Globigerinoides ruber in the sediment core may be correlated to Dansgaard-Oeschger events in the northern North Atlantic. Furthermore an increase in relative abundance of Globorotalia rubescens occurs synchronous with ice rafted debris layers described from the North Atlantic. The faunal changes in the tropical Atlantic may thus be correlated to major climate changes in the North Atlantic, mainly D-O cyclicity as well as Heinrich events. Thus, the synchronous change in water mass distribution and hydrographic cyclicity suggests a possible linkage

Impact of North Atlantic Current changes on the Nordic Seas and the Arctic Ocean

OpenAIRE

Kauker, Frank; Gerdes, Rüdiger; Karcher, Michael; Köberle, Cornelia

2005-01-01

The impact of North Atlantic Current (NAC) volume, heat, and salt transport variability onto the NordicSeas and the Arctic Ocean is investigated using numerical hindcast and sensitivity experiments. Theocean-sea ice model reproduces observed propagation pathways and speeds of SST anomalies.Part of the signal reaching the entrance to the Nordic Seas between Iceland and Scotland originatesin the lower latitude North Atlantic. Response experiments with different prescribed conditionsat 50N show ...

Variability of North Sea pH and CO2 in response to North Atlantic Oscillation forcing

DEFF Research Database (Denmark)

Salt, Lesley A.; Thomas, Helmuth; Prowe, Friederike

2013-01-01

[1] High biological activity causes a distinct seasonality of surface water pH in the North Sea, which is a strong sink for atmospheric CO2 via an effective shelf pump. The intimate connection between the North Sea and the North Atlantic Ocean suggests that the variability of the CO2 system...... of the North Atlantic Ocean may, in part, be responsible for the observed variability of pH and CO2 in the North Sea. In this work, we demonstrate the role of the North Atlantic Oscillation (NAO), the dominant climate mode for the North Atlantic, in governing this variability. Based on three extensive...... observational records covering the relevant levels of the NAO index, we provide evidence that the North Sea pH and CO2 system strongly responds to external and internal expressions of the NAO. Under positive NAO, the higher rates of inflow of water from the North Atlantic Ocean and the Baltic outflow lead...

Interannual-to-decadal air-sea interactions in the tropical Atlantic region

Science.gov (United States)

Ruiz-Barradas, Alfredo

2001-09-01

The present research identifies modes of atmosphere-ocean interaction in the tropical Atlantic region and the mechanisms by which air-sea interactions influence the regional climate. Novelties of the present work are (1)the use of relevant ocean and atmosphere variables important to identity coupled variability in the system. (2)The use of new data sets, including realistic diabatic heating. (3)The study of interactions between ocean and atmosphere relevant at interannual-to-decadal time scales. Two tropical modes of variability are identified during the period 1958-1993, the Atlantic Niño mode and the Interhemispheric mode. Those modes have defined structures in both ocean and atmosphere. Anomalous sea surface temperatures and winds are associated to anomalous placement of the Intertropical Convergence Zone (ITCZ). They develop maximum amplitude during boreal summer and spring, respectively. The anomalous positioning of the ITCZ produces anomalous precipitation in some places like Nordeste, Brazil and the Caribbean region. Through the use of a diagnostic primitive equation model, it is found that the most important terms controlling local anomalous surface winds over the ocean are boundary layer temperature gradients and diabatic heating anomalies at low levels (below 780 mb). The latter is of particular importance in the deep tropics in producing the anomalous meridional response to the surface circulation. Simulated latent heat anomalies indicate that a thermodynamic feedback establishes positive feedbacks at both sides of the equator and west of 20°W in the deep tropics and a negative feedback in front of the north west coast of Africa for the Interhemispheric mode. This thermodynamic feedback only establishes negative feedbacks for the Atlantic Niño mode. Transients establish some connection between the tropical Atlantic and other basins. Interhemispheric gradients of surface temperature in the tropical Atlantic influence winds in the midlatitude North

Environmental change studies in the Caspian Sea and the north-east Atlantic Ocean

International Nuclear Information System (INIS)

Povinec, P.; Oregioni, B.; GASTAUD, J.

2002-01-01

Caspian Sea and NE Atlantic water profiles were investigated for radionuclide content. Radionuclide data on the water samples collected in 1995 and 1996 in the Caspian Sea show a rapid exchange of water masses in the two deep basins (the Central and Southern Basins). The main source of radionuclides is global fallout. In the NE Atlantic Ocean elevated concentrations of 3 H and 4 C were observed at medium depths (2000-3000 m) which could be explained by high latitude injection processes. (author)

76 FR 36511 - Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab; Amendment 3

Science.gov (United States)

2011-06-22

...-BA22 Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab; Amendment 3 AGENCY... the Atlantic Deep-Sea Red Crab Fishery Management Plan (FMP) (Amendment 3), incorporating a draft... current trap limit regulations state that red crab may not be harvested from gear other than a marked red...

North Atlantic teleconnection patterns signature on sea level from satellite altimetry

Science.gov (United States)

Iglesias, Isabel; Lázaro, Clara; Joana Fernandes, M.; Bastos, Luísa

2015-04-01

Presently, satellite altimetry record is long enough to appropriately study inter-annual signals in sea level anomaly and ocean surface circulation, allowing the association of teleconnection patterns of low-frequency variability with the response of sea level. The variability of the Atlantic Ocean at basin-scale is known to be complex in space and time, with the dominant mode occurring on annual timescales. However, interannual and decadal variability have already been documented in sea surface temperature. Both modes are believed to be linked and are known to influence sea level along coastal regions. The analysis of the sea level multiannual variability is thus essential to understand the present climate and its long-term variability. While in the open-ocean sea level anomaly from satellite altimetry currently possesses centimetre-level accuracy, satellite altimetry measurements become invalid or of lower accuracy along the coast due to the invalidity of the wet tropospheric correction (WTC) derived from on-board microwave radiometers. In order to adequately analyse long-term changes in sea level in the coastal regions, satellite altimetry measurements can be recovered by using an improved WTC computed from recent algorithms that combine wet path delays from all available observations (remote sensing scanning imaging radiometers, GNSS stations, microwave radiometers on-board satellite altimetry missions and numerical weather models). In this study, a 20-year (1993-2013) time series of multi-mission satellite altimetry (TOPEX/Poseidon, Jason-1, OSTM/Jason-2, ERS-1/2, ENVISAT, CryoSat-2 and SARAL), are used to characterize the North Atlantic (NA) long-term variability on sea level at basin-scale and analyse its response to several atmospheric teleconnections known to operate on the NA. The altimetry record was generated using an improved coastal WTC computed from either the GNSS-derived path Delay or the Data Combination methodologies developed by University of

Topex-Poseidon analysis of sea level variability over the Atlantic Ocean

Science.gov (United States)

Catalan P-U, M.; Villares, P.; Catalan, M.; Gomez-Enri, J.

2003-04-01

The variability of sea level and surface geostrophic currents in Atlantic Ocean is investigated using 333 cycles of altimeter information obtained by TOPEX-POSEIDON satellite. After the improvements of orbit accuracy, the most important concern to studies of sea level variability from altimeter height data are related with the formalism used for modelling the altimetric measurement corrections. Presently, one of the main sources of potential error is the correction for atmospheric pressure loading, the so-called ‘inverse barometer effect’. As is well known, this correction is intended to adjust the sea surface elevation for the static effects of the downward force of the mass of the atmosphere on the sea surface, adjusted, in this oversimplified model in 1cm/mbar. The exact response of the sea surface to atmospheric pressure loading depends on the space and time scales of the pressure field and must be specially a concern at high latitudes where atmospheric pressure fluctuations are large due to the intensity of low pressure fields at these latitudes and the additional uncertainty in the model estimates of the local sea level pressure. To study these effects over the whole Atlantic Ocean we compute a linear regression adjustment and an Empirical Orthogonal Functions Decomposition (EOFD), between sea level variation without inverse barometer correction and the atmospheric pressure, in all the Topex-Poseidon cross points over the whole Atlantic, including both the Artic and Antarctic Oceans. We use the barometric factor computed from the linear regression to correct the satellite mean sea level variation, comparing the correlation with the pressure. Our results show an important improvement in the decorrelation between sea level and atmospheric pressure time series, compared with the use of Inverse Barometer model, at most of the satellite cross points. The complicated nature of sea level variability at high latitudes justify that EOFD analysis conclusions

Influence of Atlantic on the warming and reduction of sea ice in the Arctic

Directory of Open Access Journals (Sweden)

G. V. Alekseev

2017-01-01

Full Text Available Influence of anomalies of the sea surface temperature (SST in low latitudes of the North Atlantic on the sea ice cover and the near-surface air temperature in the marine Arctic is discussed in the article. Data on the SST in the Atlantic Ocean from the HadISST dataset, climatic series of the water temperature at the section along the Kola meridian together with mean monthly data on the sea ice extent and the air surface temperature in the Maritime Arctic and the Northern hemisphere were analyzed. Multivariate cross-correlation analysis was applied to determine the maximum correlation coefficients between the SST anomalies, climate characteristics and their corresponding delays within time limits of 33 to 38 months. Existence of intimate link had been found between changes of the Atlantic SST in low latitudes and the sea ice extent in the Arctic with correlation coefficients up to 0.90 and delays up to 3 years. A mechanism of formation of the remote influence of low-latitude SST anomalies on the sea ice anomalies in the Arctic Ocean is proposed. The interpretation of this mechanism includes into consideration the interaction between atmospheric and oceanic circulation modes.

Temperature, Salinity, Oxygen, Phosphate, pH and Alkalinity data collected in the North Atlantic Ocean, Baltic Sea, Barents Sea, Greenland Sea, North Sea, Norwegian Sea and White Sea from R/Vs Artemovsk, Atlantida, Okeanograf, Professor Rudovits, and ice observations, 1957 - 1995 (NODC Accession 0073674)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature, Salinity, Oxygen, Phosphate, pH and Alkalinity data collected in the North Atlantic Ocean, Baltic Sea, Barents Sea, Greenland Sea, North Sea, Norwegian...

Astronomically paced middle Eocene deepwater circulation in the western North Atlantic

Science.gov (United States)

Vahlenkamp, Maximilian; Niezgodzki, Igor; De Vleeschouwer, David; Bickert, Torsten; Harper, Dustin; Lohmann, Gerrit; Pälike, Heiko; Zachos, James C.

2017-04-01

The role of the Atlantic Meridional Overturning Circulation (AMOC) as a key player for abrupt climatic changes (e.g. Heinrich Stadials) during the Pleistocene is relatively well constrained. However, the timing of the onset of a „modern" North Atlantic Deepwater (NADW) formation are still debated: Recent estimates range from the middle Miocene to the Early Eocene [Davies et al., 2001, Stoker et al., 2005, Hohbein et al., 2012] and are mainly based on the seismic interpretation contourite drifts. Another understudied aspect of the AMOC is its behavior during climatic variations on orbital time scales and under different climatic boundary conditions (icehouse vs hothouse). IODP Expedition 342 drilled carbonate-rich sequences from sediment drifts offshore Newfoundland that cover the middle Eocene with high sedimentation rates ( 3 cm/ kyr). We present a 2 Myr long stable carbon and oxygen isotope record of benthic foraminifera nuttalides truempyi spanning magnetochron C20r in unprecedented resolution (Petroleum Geology, v. 22, no. 9, p. 977-1005. Hohbein, M. W., Sexton, P. F., and Cartwright, J. A., 2012, Onset of North Atlantic Deep Water production coincident with inception of the Cenozoic global cooling trend: Geology, v. 40, no. 3, p. 255-258.

Modeling the Middle Jurassic ocean circulation

Directory of Open Access Journals (Sweden)

Maura Brunetti

2015-10-01

Full Text Available We present coupled ocean–sea-ice simulations of the Middle Jurassic (∼165 Ma when Laurasia and Gondwana began drifting apart and gave rise to the formation of the Atlantic Ocean. Since the opening of the Proto-Caribbean is not well constrained by geological records, configurations with and without an open connection between the Proto-Caribbean and Panthalassa are examined. We use a sea-floor bathymetry obtained by a recently developed three-dimensional (3D elevation model which compiles geological, palaeogeographical and geophysical data. Our original approach consists in coupling this elevation model, which is based on detailed reconstructions of oceanic realms, with a dynamical ocean circulation model. We find that the Middle Jurassic bathymetry of the Central Atlantic and Proto-Caribbean seaway only allows for a weak current of the order of 2 Sv in the upper 1000 m even if the system is open to the west. The effect of closing the western boundary of the Proto-Caribbean is to increase the transport related to barotropic gyres in the southern hemisphere and to change water properties, such as salinity, in the Neo-Tethys. Weak upwelling rates are found in the nascent Atlantic Ocean in the presence of this superficial current and we discuss their compatibility with deep-sea sedimentological records in this region.

Continental slope sea level and flow variability induced by lateral movements of the Gulf Stream in the Middle Atlantic Bight

Science.gov (United States)

Böhm, E.; Hopkins, T. S.; Pietrafesa, L. J.; Churchill, J. H.

2006-08-01

As described by [Csanady, G.T., Hamilton, P., 1988. Circulation of slope water. Continental Shelf Research 8, 565-624], the flow regime over the slope of the southern Middle Atlantic Bight (MAB) includes a current reversal in which southwestward flow over the upper and middle slope becomes entrained in the northeastward current adjacent to the Gulf Stream. In this paper we use satellite-derived data to quantify how lateral motions of the Gulf Stream impact this current system. In our analysis, the Gulf Stream’s thermal front is delineated using a two-year time series of sea surface temperature derived from NOAA/AVHRR satellite data. Lateral motions of the Gulf Stream are represented in terms of temporal variations of the area, east of 73°W, between the Gulf Stream thermal front and the shelf edge. Variations of slope water flow within this area are represented by anomalies of geostrophic velocity as derived from the time series of the sea level anomaly determined from TOPEX/POSEIDON satellite altimeter data. A strong statistical relationship is found between Gulf Stream displacements and parabathic flow over the continental slope. It is such that the southwestward flow over the slope is accelerated when the Gulf Stream is relatively far from the shelf edge, and is decelerated (and perhaps even reversed) when the Gulf Stream is close to the shelf edge. This relationship between Gulf Stream displacements and parabathic flow is also observed in numerical simulations produced by the Miami Isopycnic Coordinate Model. In qualitative terms, it is consistent with the notion that when the Gulf Stream is closer to the 200-m isobath, it is capable of entraining a larger fraction of shelf water masses. Alternatively, when the Gulf Stream is far from the shelf-break, more water is advected into the MAB slope region from the northeast. Analysis of the diabathic flow indicates that much of the cross-slope transport by which the southwestward flow entering the study region is

76 FR 60379 - Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab; Amendment 3

Science.gov (United States)

2011-09-29

.... 100903433-1531-02] RIN 0648-BA22 Fisheries of the Northeastern United States; Atlantic Deep-Sea Red Crab... approved in Amendment 3 to the Atlantic Deep-Sea Red Crab Fishery Management Plan (FMP). The New England... ABC control rule.'' The NS1 guidelines further state that ``ABC may not exceed OFL,'' and that ``the...

Seamount physiography and biology in North-East Atlantic and Mediterranean Sea

OpenAIRE

T. Morato; K. Ø. Kvile; G. H. Taranto; F. Tempera; B. E. Narayanaswamy; D. Hebbeln; G. Menezes; C. Wienberg; R. S. Santos; T. J. Pitcher

2012-01-01

This work aims at characterising the seamount physiography and biology in the OSPAR Convention limits (North-East Atlantic Ocean) and Mediterranean Sea. We first inferred potential abundance, location and morphological characteristics of seamounts, and secondly, summarized the existing biological, geological and oceanographic in-situ research, identifying examples of well-studied seamounts. Our study showed that the seamount population in the OSPAR area (North-East Atlantic) and in Mediterran...

Distribution by origin and sea age of Atlantic salmon (Salmo salar) in the sea around the Faroe Islands based on analysis of historical tag recoveries

DEFF Research Database (Denmark)

Jacobsen, Jan Arge; Hansen, Lars P.; Bakkestuen, Vegar

2012-01-01

Distribution by origin and sea age of Atlantic salmon (Salmo salar) in the sea around the Faroe Islands based on analysis of historical tag recoveries. – ICES Journal of Marine Science, 69: 1598–1608.A database of 2651 tags applied to Atlantic salmon (Salmo salar) smolts in 13 countries...

Jurassic domes in the North Sea - northern North Atlantic region

Energy Technology Data Exchange (ETDEWEB)

Surlyk, F. [Univ. of Copenhagen, Geological Inst., Copenhagen (Denmark)

1996-12-31

The stratigraphic and tectonic evolution of the Jurassic of East Greenland, the Norwegian Shelf and the North Sea is remarkably similar. A major Middle Jurassic unconformity occurs in all three areas. In the North Sea it is commonly termed the `Mid-Cimmerian Unconformity` and is characterized by progressive truncation of the underlying section towards a centre at the triple junction between the Central Graben, Viking Graben and Moray Firth. Strata above the unconformity show a progressive Late Aalenian-Early Kimmeridgian onlap in the same direction. These relations have been interpreted as caused by Early Jurassic uplift and of a major thermal dome in the central North Sea, followed by Medial and Late Jurassic rifting, erosion, deflation and transgression of the dome. The East Greenland unconformity shows progressive truncation of underlying strata from south to north, and Bajocian to Callovian onlap in the same direction. The same pattern seems to be developed on the conjugate Norwegian margin. This suggests the possibility that the three unconformities have similar causes for their development. It is proposed that major rift domes formed in the Central North Sea and in the Greenland-Norway seaway in Early Jurassic times. The domes were eroded and gradually deflated during Medial Jurassic times and were finally submerged by the Late Oxfordian-Kimmeridgian. They were associated with volcanism and rifting which was delayed with respect to dome initiation. Roughly contemperaneous domes were present west of Britain, north of the Porcupine Seabight, and in Scania, southern Sweden, as reflected by development of asymmetrical unconformities showing progressive truncation of underlying strata, onlap of overlying Jurassic strata, and associated intrusive and extrusive volcanism. The domes are related to impingement of the heads of transient mantle plumes at the base of the lithosphere. The associated unconformities are thus of non-eustatic nature. Domal uplift and

Recent increases in Arctic freshwater flux affects Labrador Sea convection and Atlantic overturning circulation

NARCIS (Netherlands)

Yang, Qian; Dixon, Timothy H.; Myers, Paul G.; Bonin, Jennifer; Chambers, Don; Van Den Broeke, M. R.|info:eu-repo/dai/nl/073765643

2016-01-01

The Atlantic Meridional Overturning Circulation (AMOC) is an important component of ocean thermohaline circulation. Melting of Greenland's ice sheet is freshening the North Atlantic; however, whether the augmented freshwater flux is disrupting the AMOC is unclear. Dense Labrador Sea Water (LSW),

Temperature, salinity, and nutrients data collected from North Atlantic Ocean, White Sea, Mediterranean Sea, Black Sea, and Sea of Azov from 1924-03-19 to 1989-11-19 by multiple Soviet Union institutes (NODC Accession 0077413)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature, salinity, and nutrients data collected from North Atlantic Ocean, White Sea, Mediterranean Sea, Black Sea, and Sea of Azov from 1924-03-19 to 1989-11-19...

Avian Influenza Ecology in North Atlantic Sea Ducks: Not All Ducks Are Created Equal

Science.gov (United States)

Hall, Jeffrey S.; Russell, Robin E.; Franson, J. Christian; Soos, Catherine; Dusek, Robert J.; Allen, R. Bradford; Nashold, Sean W.; TeSlaa, Joshua L.; Jónsson, Jón Eínar; Ballard, Jennifer R.; Harms, Naomi Jane; Brown, Justin D.

2015-01-01

Wild waterfowl are primary reservoirs of avian influenza viruses (AIV). However the role of sea ducks in the ecology of avian influenza, and how that role differs from freshwater ducks, has not been examined. We obtained and analyzed sera from North Atlantic sea ducks and determined the seroprevalence in those populations. We also tested swab samples from North Atlantic sea ducks for the presence of AIV. We found relatively high serological prevalence (61%) in these sea duck populations but low virus prevalence (0.3%). Using these data we estimated that an antibody half-life of 141 weeks (3.2 years) would be required to attain these prevalences. These findings are much different than what is known in freshwater waterfowl and have implications for surveillance efforts, AIV in marine environments, and the roles of sea ducks and other long-lived waterfowl in avian influenza ecology. PMID:26677841

Avian influenza ecology in North Atlantic sea ducks: Not all ducks are created equal

Science.gov (United States)

Hall, Jeffrey S.; Russell, Robin E.; Franson, J. Christian; Soos, Catherine; Dusek, Robert J.; Allen, R. Bradford; Nashold, Sean W.; Teslaa, Joshua L.; Jónsson, Jón Einar; Ballard, Jennifer R.; Harms, Naomi Jnae; Brown, Justin D.

2015-01-01

Wild waterfowl are primary reservoirs of avian influenza viruses (AIV). However the role of sea ducks in the ecology of avian influenza, and how that role differs from freshwater ducks, has not been examined. We obtained and analyzed sera from North Atlantic sea ducks and determined the seroprevalence in those populations. We also tested swab samples from North Atlantic sea ducks for the presence of AIV. We found relatively high serological prevalence (61%) in these sea duck populations but low virus prevalence (0.3%). Using these data we estimated that an antibody half-life of 141 weeks (3.2 years) would be required to attain these prevalences. These findings are much different than what is known in freshwater waterfowl and have implications for surveillance efforts, AIV in marine environments, and the roles of sea ducks and other long-lived waterfowl in avian influenza ecology.

Splitting of Atlantic water transport towards the Arctic Ocean into the Fram Strait and Barents Sea Branches - mechanisms and consequences

Science.gov (United States)

Beszczynska-Möller, Agnieszka; Skagseth, Øystein; von Appen, Wilken-Jon; Walczowski, Waldemar; Lien, Vidar

2016-04-01

The heat content in the Arctic Ocean is to a large extent determined by oceanic advection from the south. During the last two decades the extraordinary warm Atlantic water (AW) inflow has been reported to progress through the Nordic Seas into the Arctic Ocean. Warm anomalies can result from higher air temperatures (smaller heat loss) in the Nordic Seas, and/or from an increased oceanic advection. But the ultimate fate of warm anomalies of Atlantic origin depends strongly on their two possible pathways towards the Arctic Ocean. The AW temperature changes from 7-10°C at the entrance to the Nordic Seas, to 6-6.5°C in the Barents Sea opening and 3-3.5°C as the AW leaving Fram Strait enters the Arctic Ocean. When AW passes through the shallow Barents Sea, nearly all its heat is lost due to atmospheric cooling and AW looses its signature. In the deep Fram Strait the upper part of Atlantic water becomes transformed into a less saline and colder surface layer and thus AW preserves its warm core. A significant warming and high variability of AW volume transport was observed in two recent decades in the West Spitsbergen Current, representing the Fram Strait Branch of Atlantic inflow. The AW inflow through Fram Strait carries between 26 and 50 TW of heat into the Arctic Ocean. While the oceanic heat influx to the Barents Sea is of a similar order, the heat leaving it through the northern exit into the Arctic Ocean is negligible. The relative strength of two Atlantic water branches through Fram Strait and the Barents Sea governs the oceanic heat transport into the Arctic Ocean. According to recently proposed mechanism, the Atlantic water flow in the Barents Sea Branch is controlled by the strength of atmospheric low over the northern Barents Sea, acting through a wind-induced Ekman divergence, which intensifies eastward AW flow. The Atlantic water transport in the Fram Strait Branch is mainly forced by the large-scale low-pressure system over the eastern Norwegian and

Interannual variability of north Atlantic Sea surface temperatures

International Nuclear Information System (INIS)

Bhatt, U.S.; Battisiti, D.S.; Alexander, M.A.

1994-01-01

In the midlatitude north Atlantic Ocean the pattern of sea surface temperature anomalies (ssta) is characterized by a north-south dipole. Bjerknes was the first to propose that the banded structure was associated with the interannual variability. Recently, these patterns have been studied more extensively. In this study the quantitative aspects of these patterns are examined through the use of a mixed-layer model (MLM)

Changes in extreme regional sea surface height due to an abrupt weakening of the Atlantic meridional overturning circulation

NARCIS (Netherlands)

Brunnabend, S.-E.; Dijkstra, H. A.; Kliphuis, M. A.; van Werkhoven, B.J.C.; Bal, H. E.; Seinstra, F.; Maassen, J.; van Meersbergen, M.

2014-01-01

As an extreme scenario of dynamical sea level changes, regional sea surface height (SSH) changes that occur in the North Atlantic due to an abrupt weakening of the Atlantic meridional overturning circulation (AMOC) are simulated. Two versions of the same ocean-only model are used to study the effect

Recent increases in Arctic freshwater flux affects Labrador Sea convection and Atlantic overturning circulation

Science.gov (United States)

Yang, Qian; Dixon, Timothy H.; Myers, Paul G.; Bonin, Jennifer; Chambers, Don; van den Broeke, M. R.

2016-01-01

The Atlantic Meridional Overturning Circulation (AMOC) is an important component of ocean thermohaline circulation. Melting of Greenland's ice sheet is freshening the North Atlantic; however, whether the augmented freshwater flux is disrupting the AMOC is unclear. Dense Labrador Sea Water (LSW), formed by winter cooling of saline North Atlantic water and subsequent convection, is a key component of the deep southward return flow of the AMOC. Although LSW formation recently decreased, it also reached historically high values in the mid-1990s, making the connection to the freshwater flux unclear. Here we derive a new estimate of the recent freshwater flux from Greenland using updated GRACE satellite data, present new flux estimates for heat and salt from the North Atlantic into the Labrador Sea and explain recent variations in LSW formation. We suggest that changes in LSW can be directly linked to recent freshening, and suggest a possible link to AMOC weakening.

Middle Range Sea Ice Prediction System of Voyage Environmental Information System in Arctic Sea Route

Science.gov (United States)

Lim, H. S.

2017-12-01

Due to global warming, the sea ice in the Arctic Ocean is melting dramatically in summer, which is providing a new opportunity to exploit the Northern Sea Route (NSR) connecting Asia and Europe ship route. Recent increases in logistics transportation through NSR and resource development reveal the possible threats of marine pollution and marine transportation accidents without real-time navigation system. To develop a safe Voyage Environmental Information System (VEIS) for vessels operating, the Korea Institute of Ocean Science and Technology (KIOST) which is supported by the Ministry of Oceans and Fisheries, Korea has initiated the development of short-term and middle range prediction system for the sea ice concentration (SIC) and sea ice thickness (SIT) in NSR since 2014. The sea ice prediction system of VEIS consists of AMSR2 satellite composite images (a day), short-term (a week) prediction system, and middle range (a month) prediction system using a statistical method with re-analysis data (TOPAZ) and short-term predicted model data. In this study, the middle range prediction system for the SIC and SIT in NSR is calibrated with another middle range predicted atmospheric and oceanic data (NOAA CFSv2). The system predicts one month SIC and SIT on a daily basis, as validated with dynamic composite SIC data extracted from AMSR2 L2 satellite images.

Seamount physiography and biology in the north-east Atlantic and Mediterranean Sea

OpenAIRE

Morato, T.; Kvile, K. Ø.; Taranto, G. H.; Tempera, F.; Narayanaswamy, B. E.; Hebbeln, D.; Menezes, G. M.; Wienberg, C.; Santos, R. S.; Pitcher, T. J.

2013-01-01

This work aims at characterising the seamount physiography and biology in the OSPAR Convention limits (north-east Atlantic Ocean) and Mediterranean Sea. We first inferred potential abundance, location and morphological characteristics of seamounts, and secondly, summarized the existing biological, geological and oceanographic in situ research, identifying examples of well-studied seamounts. Our study showed that the seamount population in the OSPAR area (north-east Atlantic) and in the Medite...

Predation on Atlantic salmon and sea trout during their first days as postsmolts

DEFF Research Database (Denmark)

Dieperink, C.; Bak, B.D.; Pedersen, Lars-Flemming

2002-01-01

Radio-tagged smolts of Atlantic salmon Salmo salar and sea trout Salmo trutta were predated heavily by sea birds after crossing the saline limit in the estuary of the River Skjern, Denmark. Most predation took place within the first 9 h after estuarine entry. The field data do not contradict...

Sea Spray Aerosol Production over the North Atlantic

Science.gov (United States)

Bates, T. S.; Quinn, P.

2017-12-01

Breaking waves on the ocean surface generate air bubbles that scavenge organic matter from the surrounding seawater. When injected into the atmosphere, these bubbles burst, yielding sea spray aerosol (SSA), a mixture of organic and inorganic compounds with the organic matter enriched relative to seawater. SSA mass is well documented as the dominant component of aerosol light scattering over the remote oceans. The importance of SSA number to marine boundary layer cloud condensation nuclei (CCN) is much less certain. During the Western Atlantic Climate Study cruises (WACS-1 - August 2012 and WACS-2 - May-June 2014) and the North Atlantic Aerosols and Marine Ecosystem Study cruises (NAAMES-1 - November 2015, NAAMES-2 - May 2016, and NAAMES-3 - September 2017), we generated and measured freshly emitted SSA using the Sea Sweep SSA generator. During the 2017 cruise we also generated SSA with a Marine Aerosol Reference Tank (MART). Using the data generated on these 5 cruises and a large database of remote marine boundary layer aerosol measurements we will address three questions during this presentation: 1 - Do phytoplankton ecosystems affect the organic enrichment of freshly emitted SSA?, 2 - Do plankton ecosystems affect the number production flux of SSA?, and 3 - Is SSA a significant source of atmospheric CCN?

Distribution patterns of wintering sea ducks in relation to the North Atlantic Oscillation and local environmental characteristics

Science.gov (United States)

Zipkin, Elise F.; Gardner, Beth; Gilbert, Andrew T.; O'Connell, Allan F.; Royle, J. Andrew; Silverman, Emily D.

2010-01-01

Twelve species of North American sea ducks (Tribe Mergini) winter off the eastern coast of the United States and Canada. Yet, despite their seasonal proximity to urbanized areas in this region, there is limited information on patterns of wintering sea duck habitat use. It is difficult to gather information on sea ducks because of the relative inaccessibility of their offshore locations, their high degree of mobility, and their aggregated distributions. To characterize environmental conditions that affect wintering distributions, as well as their geographic ranges, we analyzed count data on five species of sea ducks (black scoters Melanitta nigra americana, surf scoters M. perspicillata, white-winged scoters M. fusca, common eiders Somateria mollissima, and long-tailed ducks Clangula hyemalis) that were collected during the Atlantic Flyway Sea Duck Survey for ten years starting in the early 1990s. We modeled count data for each species within ten-nautical-mile linear survey segments using a zero-inflated negative binomial model that included four local-scale habitat covariates (sea surface temperature, mean bottom depth, maximum bottom slope, and a variable to indicate if the segment was in a bay or not), one broad-scale covariate (the North Atlantic Oscillation), and a temporal correlation component. Our results indicate that species distributions have strong latitudinal gradients and consistency in local habitat use. The North Atlantic Oscillation was the only environmental covariate that had a significant (but variable) effect on the expected count for all five species, suggesting that broad-scale climatic conditions may be directly or indirectly important to the distributions of wintering sea ducks. Our results provide critical information on species-habitat associations, elucidate the complicated relationship between the North Atlantic Oscillation, sea surface temperature, and local sea duck abundances, and should be useful in assessing the impacts of climate

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

Science.gov (United States)

2010-05-14

.... Whereas a limited market has been responsible for the shortfall in landings compared to the target TAC... final specifications for the 2010 Atlantic deep- sea red crab fishery, including a target total... specify the target TAC and other management measures in order to manage the red crab resource for fishing...

Climate drift of AMOC, North Atlantic salinity and arctic sea ice in CFSv2 decadal predictions

Science.gov (United States)

Huang, Bohua; Zhu, Jieshun; Marx, Lawrence; Wu, Xingren; Kumar, Arun; Hu, Zeng-Zhen; Balmaseda, Magdalena A.; Zhang, Shaoqing; Lu, Jian; Schneider, Edwin K.; Kinter, James L., III

2015-01-01

There are potential advantages to extending operational seasonal forecast models to predict decadal variability but major efforts are required to assess the model fidelity for this task. In this study, we examine the North Atlantic climate simulated by the NCEP Climate Forecast System, version 2 (CFSv2), using a set of ensemble decadal hindcasts and several 30-year simulations initialized from realistic ocean-atmosphere states. It is found that a substantial climate drift occurs in the first few years of the CFSv2 hindcasts, which represents a major systematic bias and may seriously affect the model's fidelity for decadal prediction. In particular, it is noted that a major reduction of the upper ocean salinity in the northern North Atlantic weakens the Atlantic meridional overturning circulation (AMOC) significantly. This freshening is likely caused by the excessive freshwater transport from the Arctic Ocean and weakened subtropical water transport by the North Atlantic Current. A potential source of the excessive freshwater is the quick melting of sea ice, which also causes unrealistically thin ice cover in the Arctic Ocean. Our sensitivity experiments with adjusted sea ice albedo parameters produce a sustainable ice cover with realistic thickness distribution. It also leads to a moderate increase of the AMOC strength. This study suggests that a realistic freshwater balance, including a proper sea ice feedback, is crucial for simulating the North Atlantic climate and its variability.

Potential contribution of surface-dwelling Sargassum algae to deep-sea ecosystems in the southern North Atlantic

Science.gov (United States)

Baker, Philip; Minzlaff, Ulrike; Schoenle, Alexandra; Schwabe, Enrico; Hohlfeld, Manon; Jeuck, Alexandra; Brenke, Nils; Prausse, Dennis; Rothenbeck, Marcel; Brix, Saskia; Frutos, Inmaculada; Jörger, Katharina M.; Neusser, Timea P.; Koppelmann, Rolf; Devey, Colin; Brandt, Angelika; Arndt, Hartmut

2018-02-01

Deep-sea ecosystems, limited by their inability to use primary production as a source of carbon, rely on other sources to maintain life. Sedimentation of organic carbon into the deep sea has been previously studied, however, the high biomass of sedimented Sargassum algae discovered during the VEMA Transit expedition in 2014/2015 to the southern North Atlantic, and its potential as a regular carbon input, has been an underestimated phenomenon. To determine the potential for this carbon flux, a literature survey of previous studies that estimated the abundance of surface water Sargassum was conducted. We compared these estimates with quantitative analyses of sedimented Sargassum appearing on photos taken with an autonomous underwater vehicle (AUV) directly above the abyssal sediment during the expedition. Organismal communities associated to Sargassum fluitans from surface waters were investigated and Sargassum samples collected from surface waters and the deep sea were biochemically analyzed (fatty acids, stable isotopes, C:N ratios) to determine degradation potential and the trophic significance within deep-sea communities. The estimated Sargassum biomass (fresh weight) in the deep sea (0.07-3.75 g/m2) was several times higher than that estimated from surface waters in the North Atlantic (0.024-0.84 g/m2). Biochemical analysis showed degradation of Sargassum occurring during sedimentation or in the deep sea, however, fatty acid and stable isotope analysis did not indicate direct trophic interactions between the algae and benthic organisms. Thus, it is assumed that components of the deep-sea microbial food web form an important link between the macroalgae and larger benthic organisms. Evaluation of the epifauna showed a diverse nano- micro-, meio, and macrofauna on surface Sargassum and maybe transported across the Atlantic, but we had no evidence for a vertical exchange of fauna components. The large-scale sedimentation of Sargassum forms an important trophic link

Evolution of Interhemispheric Sea-Surface Temperature Contrast in the Tropical Atlantic During Termination I

Science.gov (United States)

Kim, J.

2001-12-01

Meteorological and oceanographic studies show that interannual and decadal variability in tropical Atlantic sea-surface temperature (SST) strongly influences the climates over northeast Brazil, sub-Saharan Africa, as well as the Central American and Caribbean regions. In this context, it is worthwhile to reconstruct spatial temperature patterns for the longer-term tropical Atlantic SST history. In this study, a high-resolution alkenone-derived SST record from the subtropical eastern South Atlantic (core GeoB 1023-5) is compared with one from the tropical western North Atlantic (core M35003-4). This comparison reveals synchronous SST variations between both near equatorial Atlantic regions during the Heinrich Event 1 (H1) (18-15.5 cal kyr B.P.), but dipole-like SST variations during the Younger Dryas (YD) (13-11.5 cal kyr B.P.). To assess the relationship of SST variations between both regions, we calculated SST differences between cores GeoB 1023-5 and M35003-4, and compared it with the coccolithophorid Florisphaera profunda abundance record from the equatorial eastern Atlantic (core RC24-08) as an indicator of variations in intensity of south-easterly trade winds [McIntyre and Molfino, 1996]. This comparison suggests that synchronous warming in both regions during the H1 can be attributed to a reduced northward heat transport from the warm equatorial Atlantic to the cold high-latitude North Atlantic linked to the slowdown of thermohaline circulation overturning during cold events under full glacial conditions. However, dipole-like SST variations during the YD is probably more associated with strengthened south-easterly trade winds, which led to a strong upwelling-related cooling in the eastern South Atlantic region and concurrently enhanced advection of warm subtropical South Atlantic waters to the tropical western Atlantic during that time. Accordingly, a coupled oceanic-atmospheric process created a warm pool in the tropical western Atlantic and thus a dipole

Wintertime re-ventilation of the East Greenland Current's Atlantic-origin Overflow Water in the western Iceland Sea

Science.gov (United States)

Våge, Kjetil; Håvik, Lisbeth; Papritz, Lukas; Spall, Michael; Moore, Kent

2017-04-01

The Deep Western Boundary Current constitutes the lower limb of the Atlantic Meridional Overturning Circulation, and, as such, is a crucial component of the Earth's climate system. The largest and densest contribution to the current stems from the overflow plume that passes through Denmark Strait. A main source of Denmark Strait Overflow Water (DSOW) is the East Greenland Current (EGC). The DSOW transported by the EGC originates from the Atlantic inflow into the Nordic Seas. This is then transformed into Atlantic-origin Overflow Water while progressing northward through the eastern part of the Nordic Seas. Here we show, using measurements from autonomous gliders deployed from fall 2015 to spring 2016, that the Atlantic-origin Overflow Water transported toward Denmark Strait by the EGC was re-ventilated while transiting the western Iceland Sea in winter. In summer, this region is characterized by an upper layer of cold, fresh Polar Surface Water that is thought to prevent convection. But in fall and winter this fresh water mass is diverted toward the Greenland shelf by enhanced northerly winds, which results in a water column that is preconditioned for convection. Severe heat loss from the ocean to the atmosphere offshore of the ice edge subsequently causes the formation of deep mixed layers. This further transforms the Atlantic-origin Overflow Water and impacts the properties of the DSOW, and hence the deepest and densest component of the lower limb of the Atlantic Meridional Overturning Circulation.

Coastal Sea Level along the North Eastern Atlantic Shelf from Delay Doppler Altimetry

Science.gov (United States)

Fenoglio-Marc, L.; Benveniste, J.; Andersen, O. B.; Gravelle, M.; Dinardo, S.; Uebbing, B.; Scharroo, R.; Kusche, J.; Kern, M.; Buchhaupt, C.

2017-12-01

Satellite altimetry data of the CryoSat-2 and Sentinel-3 missions processed with Delay Doppler methodology (DDA) provide improved coastal sea level measurements up to 2-4 km from coast, thanks to an along-track resolution of about 300m and a higher signal to noise ratio. We investigate the 10 Kilometre stripe along the North-Eastern Atlantic shelf from Lisbon to Bergen to detect the possible impacts in sea level change studies of this enhanced dataset. We consider SAR CryoSat-2 and Sentinel-3 altimetry products from the ESA GPOD processor and in-house reduced SAR altimetry (RDSAR) products. Improved processing includes in RDSAR the application of enhanced retrackers for the RDSAR waveform. Improved processing in SAR includes modification both in the generation of SAR waveforms, (as Hamming weighting window on the burst data prior to the azimuth FFT, zero-padding prior to the range FFT, doubling of the extension for the radar range swath) and in the SAMOSA2 retracker. Data cover the full lifetime of CryoSat-2 (6 years) and Sentinel-3 (1 year). Conventional altimetry are from the sea level CCI database. First we analyse the impact of these SAR altimeter data on the sea level trend and on the estimation of vertical motion from the altimeter minus tide gauge differences. VLM along the North-Eastern Atlantic shelf is generally small compared to the North-Western Atlantic Coast VLM, with a smaller signal to noise ratio. Second we investigate impact on the coastal mean sea level surface and the mean dynamic topography. We evaluate a mean surface from the new altimeter data to be combined to state of the art geoid models to derive the mean dynamic topography. We compare the results to existing oceanographic and geodetic mean dynamic topography solutions, both on grid and pointwise at the tide gauge stations. This study is supported by ESA through the Sea Level CCI and the GOCE++DYCOT projects

Bacterial diversity and biogeography in deep-sea sediments of the South Atlantic Ocean

DEFF Research Database (Denmark)

Schauer, Regina; Bienhold, Christina; Ramette, Alban

2010-01-01

in 1051 sequences. Phylotypes affiliated with Gammaproteobacteria, Deltaproteobacteria and Acidobacteria were present in all three basins. The distribution of these shared phylotypes seemed to be influenced neither by the Walvis Ridge nor by different deep water masses, suggesting a high dispersal......Microbial biogeographic patterns in the deep sea depend on the ability of microorganisms to disperse. One possible limitation to microbial dispersal may be the Walvis Ridge that separates the Antarctic Lower Circumpolar Deep Water from the North Atlantic Deep Water. We examined bacterial...... communities in three basins of the eastern South Atlantic Ocean to determine diversity and biogeography of bacterial communities in deep-sea surface sediments. The analysis of 16S ribosomal RNA (rRNA) gene clone libraries in each basin revealed a high diversity, representing 521 phylotypes with 98% identity...

Bathymetric controls on Pliocene North Atlantic and Arctic sea surface temperature and deepwater production

Science.gov (United States)

Robinson, M.M.; Valdes, P.J.; Haywood, A.M.; Dowsett, H.J.; Hill, D.J.; Jones, S.M.

2011-01-01

The mid-Pliocene warm period (MPWP; ~. 3.3 to 3.0. Ma) is the most recent interval in Earth's history in which global temperatures reached and remained at levels similar to those projected for the near future. The distribution of global warmth, however, was different than today in that the high latitudes warmed more than the tropics. Multiple temperature proxies indicate significant sea surface warming in the North Atlantic and Arctic Oceans during the MPWP, but predictions from a fully coupled ocean-atmosphere model (HadCM3) have so far been unable to fully predict the large scale of sea surface warming in the high latitudes. If climate proxies accurately represent Pliocene conditions, and if no weakness exists in the physics of the model, then model boundary conditions may be in error. Here we alter a single boundary condition (bathymetry) to examine if Pliocene high latitude warming was aided by an increase in poleward heat transport due to changes in the subsidence of North Atlantic Ocean ridges. We find an increase in both Arctic sea surface temperature and deepwater production in model experiments that incorporate a deepened Greenland-Scotland Ridge. These results offer both a mechanism for the warming in the North Atlantic and Arctic Oceans indicated by numerous proxies and an explanation for the apparent disparity between proxy data and model simulations of Pliocene northern North Atlantic and Arctic Ocean conditions. Determining the causes of Pliocene warmth remains critical to fully understanding comparisons of the Pliocene warm period to possible future climate change scenarios. ?? 2011.

Northward advection of Atlantic water in the eastern Nordic Seas over the last 3000 yr

Directory of Open Access Journals (Sweden)

C. V. Dylmer

2013-07-01

Full Text Available Three marine sediment cores distributed along the Norwegian (MD95-2011, Barents Sea (JM09-KA11-GC, and Svalbard (HH11-134-BC continental margins have been investigated in order to reconstruct changes in the poleward flow of Atlantic waters (AW and in the nature of upper surface water masses within the eastern Nordic Seas over the last 3000 yr. These reconstructions are based on a limited set of coccolith proxies: the abundance ratio between Emiliania huxleyi and Coccolithus pelagicus, an index of Atlantic vs. Polar/Arctic surface water masses; and Gephyrocapsa muellerae, a drifted coccolith species from the temperate North Atlantic, whose abundance changes are related to variations in the strength of the North Atlantic Current. The entire investigated area, from 66 to 77° N, was affected by an overall increase in AW flow from 3000 cal yr BP (before present to the present. The long-term modulation of westerlies' strength and location, which are essentially driven by the dominant mode of the North Atlantic Oscillation (NAO, is thought to explain the observed dynamics of poleward AW flow. The same mechanism also reconciles the recorded opposite zonal shifts in the location of the Arctic front between the area off western Norway and the western Barents Sea–eastern Fram Strait region. The Little Ice Age (LIA was governed by deteriorating conditions, with Arctic/Polar waters dominating in the surface off western Svalbard and western Barents Sea, possibly associated with both severe sea ice conditions and a strongly reduced AW strength. A sudden short pulse of resumed high WSC (West Spitsbergen Current flow interrupted this cold spell in eastern Fram Strait from 330 to 410 cal yr BP. Our dataset not only confirms the high amplitude warming of surface waters at the turn of the 19th century off western Svalbard, it also shows that such a warming was primarily induced by an excess flow of AW which stands as unprecedented over the last 3000 yr.

Mid-Holocene Strengthening of the Bering Strait Inflow to the Arctic and its Linkage With the North Atlantic Subpolar Gyre Circulation

Science.gov (United States)

Yamamoto, M.; Nam, S. I.; Polyak, L.; Kobayashi, D.; Suzuki, K.; Irino, T.; Shimada, K.

2017-12-01

The Bering Strait inflow (BSI) is an important element of the Arctic Ocean circulation system. We report records of the chlorite/illite ratios in three sediment cores from the northern Chukchi Sea providing insights into the long-term dynamics of the BSI during the Holocene. The BSI approximation by the chlorite/illite record, despite a considerable geographic variability, consistently shows intensified flow from the Bering Sea to the Arctic during the middle Holocene, which is attributed primarily to the effect of higher atmospheric pressure over the Aleutian Basin. The intensified BSI was associated with decrease in sea-ice concentrations and increase in marine production, as indicated by biomarker concentrations, suggesting a major influence of the BSI on sea-ice and biological conditions in the Chukchi Sea. Multi-century to millennial fluctuations, presumably controlled by solar activity, were also identified. This middle Holocene strengthening of the BSI was coeval with intense subpolar gyre circulation in the North Atlantic. We propose that the BSI is linked with the North Atlantic circulation via an atmospheric teleconnection between the Aleutian and Icelandic Lows.

Contrasting trends in North Atlantic deep-water formation in the Labrador Sea and Nordic Seas during the Holocene

NARCIS (Netherlands)

Renssen, H.; Goosse, H.; Fichefet, T.

2005-01-01

The Holocene North Atlantic deep-water formation is studied in a 9,000-year long simulation with a coupled climate model of intermediate complexity, forced by changes in orbital forcing and atmospheric trace gas concentrations. During the experiment, deep-water formation in the Nordic Seas is

Astronomically paced changes in deep-water circulation in the western North Atlantic during the middle Eocene

Science.gov (United States)

Vahlenkamp, Maximilian; Niezgodzki, Igor; De Vleeschouwer, David; Bickert, Torsten; Harper, Dustin; Kirtland Turner, Sandra; Lohmann, Gerrit; Sexton, Philip; Zachos, James; Pälike, Heiko

2018-02-01

North Atlantic Deep Water (NADW) currently redistributes heat and salt between Earth's ocean basins, and plays a vital role in the ocean-atmosphere CO2 exchange. Despite its crucial role in today's climate system, vigorous debate remains as to when deep-water formation in the North Atlantic started. Here, we present datasets from carbonate-rich middle Eocene sediments from the Newfoundland Ridge, revealing a unique archive of paleoceanographic change from the progressively cooling climate of the middle Eocene. Well-defined lithologic alternations between calcareous ooze and clay-rich intervals occur at the ∼41-kyr beat of axial obliquity. Hence, we identify obliquity as the driver of middle Eocene (43.5-46 Ma) Northern Component Water (NCW, the predecessor of modern NADW) variability. High-resolution benthic foraminiferal δ18O and δ13C suggest that obliquity minima correspond to cold, nutrient-depleted, western North Atlantic deep waters. We thus link stronger NCW formation with obliquity minima. In contrast, during obliquity maxima, Deep Western Boundary Currents were weaker and warmer, while abyssal nutrients were more abundant. These aspects reflect a more sluggish NCW formation. This obliquity-paced paleoceanographic regime is in excellent agreement with results from an Earth system model, in which obliquity minima configurations enhance NCW formation.

Solar wind: A possible factor driving the interannual sea surface temperature tripolar mode over North Atlantic

Science.gov (United States)

Xiao, Ziniu; Li, Delin

2016-06-01

The effect of solar wind (SW) on the North Atlantic sea surface temperature (SST) in boreal winter is examined through an analysis of observational data during 1964-2013. The North Atlantic SSTs show a pronounced meridional tripolar pattern in response to solar wind speed (SWS) variations. This pattern is broadly similar to the leading empirical orthogonal function (EOF) mode of interannual variations in the wintertime SSTs over North Atlantic. The time series of this leading EOF mode of SST shows a significant interannual period, which is the same as that of wintertime SWS. This response also appears as a compact north-south seesaw of sea level pressure and a vertical tripolar structure of zonal wind, which simultaneously resembles the North Atlantic Oscillation (NAO) in the overlying atmosphere. As compared with the typical low SWS winters, during the typical high SWS winters, the stratospheric polar night jet (PNJ) is evidently enhanced and extends from the stratosphere to the troposphere, even down to the North Atlantic Ocean surface. Notably, the North Atlantic Ocean is an exclusive region in which the SW signal spreads downward from the stratosphere to the troposphere. Thus, it seems that the SW is a possible factor for this North Atlantic SST tripolar mode. The dynamical process of stratosphere-troposphere coupling, together with the global atmospheric electric circuit-cloud microphysical process, probably accounts for the particular downward propagation of the SW signal.

Evidence for middle Eocene Arctic sea ice from diatoms and ice-rafted debris.

Science.gov (United States)

Stickley, Catherine E; St John, Kristen; Koç, Nalân; Jordan, Richard W; Passchier, Sandra; Pearce, Richard B; Kearns, Lance E

2009-07-16

Oceanic sediments from long cores drilled on the Lomonosov ridge, in the central Arctic, contain ice-rafted debris (IRD) back to the middle Eocene epoch, prompting recent suggestions that ice appeared in the Arctic about 46 million years (Myr) ago. However, because IRD can be transported by icebergs (derived from land-based ice) and also by sea ice, IRD records are restricted to providing a history of general ice-rafting only. It is critical to differentiate sea ice from glacial (land-based) ice as climate feedback mechanisms vary and global impacts differ between these systems: sea ice directly affects ocean-atmosphere exchanges, whereas land-based ice affects sea level and consequently ocean acidity. An earlier report assumed that sea ice was prevalent in the middle Eocene Arctic on the basis of IRD, and although somewhat preliminary supportive evidence exists, these data are neither comprehensive nor quantified. Here we show the presence of middle Eocene Arctic sea ice from an extraordinary abundance of a group of sea-ice-dependent fossil diatoms (Synedropsis spp.). Analysis of quartz grain textural characteristics further supports sea ice as the dominant transporter of IRD at this time. Together with new information on cosmopolitan diatoms and existing IRD records, our data strongly suggest a two-phase establishment of sea ice: initial episodic formation in marginal shelf areas approximately 47.5 Myr ago, followed approximately 0.5 Myr later by the onset of seasonally paced sea-ice formation in offshore areas of the central Arctic. Our data establish a 2-Myr record of sea ice, documenting the transition from a warm, ice-free environment to one dominated by winter sea ice at the start of the middle Eocene climatic cooling phase.

Trophic impact of Atlantic bluefin tuna migrations in the North Sea

DEFF Research Database (Denmark)

Mariani, Patrizio; Andersen, Ken Haste; Lindegren, Martin

2017-01-01

and the stability of the fish community. The impact of a migrating top-predator is investigated here for Atlantic bluefin tuna in the North Sea. Bluefin tuna has been absent from the region for half-century, but recent years have seen recovery of migrations and a return of bluefin tuna in the area. We use a size...

Summer Sea Ice Motion from the 18 GHz Channel of AMSR-E and the Exchange of Sea Ice between the Pacific and Atlantic Sectors

Science.gov (United States)

Kwok, Ronald

2008-01-01

We demonstrate that sea ice motion in summer can be derived reliably from the 18GHz channel of the AMSR-E instrument on the EOS Aqua platform. The improved spatial resolution of this channel with its lower sensitivity to atmospheric moisture seems to have alleviated various issues that have plagued summer motion retrievals from shorter wavelength observations. Two spatial filters improve retrieval quality: one reduces some of the microwave signatures associated with synoptic-scale weather systems and the other removes outliers. Compared with daily buoy drifts, uncertainties in motion are approx.3-4 km/day. Using the daily motion fields, we examine five years of summer ice area exchange between the Pacific and Atlantic sectors of the Arctic Ocean. With the sea-level pressure patterns during the summer of 2006 and 2007 favoring the export of sea ice into the Atlantic Sector, the regional outflow is approx.21% and approx.15% of the total sea ice retreat in the Pacific sector.

Ecological regime shift drives declining growth rates of sea turtles throughout the West Atlantic

Science.gov (United States)

Bjorndal, Karen A.; Bolten, Alan B.; Chaloupka, Milani; Saba, Vincent S.; Bellini, Cláudio; Marcovaldi, Maria A.G.; Santos, Armando J.B.; Bortolon, Luis Felipe Wurdig; Meylan, Anne B.; Meylan, Peter A.; Gray, Jennifer; Hardy, Robert; Brost, Beth; Bresette, Michael; Gorham, Jonathan C.; Connett, Stephen; Crouchley, Barbara Van Sciver; Dawson, Mike; Hayes, Deborah; Diez, Carlos E.; van Dam, Robert P.; Willis, Sue; Nava, Mabel; Hart, Kristen M.; Cherkiss, Michael S.; Crowder, Andrew; Pollock, Clayton; Hillis-Starr, Zandy; Muñoz Tenería, Fernando A.; Herrera-Pavón, Roberto; Labrada-Martagón, Vanessa; Lorences, Armando; Negrete-Philippe, Ana; Lamont, Margaret M.; Foley, Allen M.; Bailey, Rhonda; Carthy, Raymond R.; Scarpino, Russell; McMichael, Erin; Provancha, Jane A.; Brooks, Annabelle; Jardim, Adriana; López-Mendilaharsu, Milagros; González-Paredes, Daniel; Estrades, Andrés; Fallabrino, Alejandro; Martínez-Souza, Gustavo; Vélez-Rubio, Gabriela M.; Boulon, Ralf H.; Collazo, Jaime; Wershoven, Robert; Hernández, Vicente Guzmán; Stringell, Thomas B.; Sanghera, Amdeep; Richardson, Peter B.; Broderick, Annette C.; Phillips, Quinton; Calosso, Marta C.; Claydon, John A.B.; Metz, Tasha L.; Gordon, Amanda L.; Landry, Andre M.; Shaver, Donna J.; Blumenthal, Janice; Collyer, Lucy; Godley, Brendan J.; McGowan, Andrew; Witt, Matthew J.; Campbell, Cathi L.; Lagueux, Cynthia J.; Bethel, Thomas L.; Kenyon, Lory

2017-01-01

Somatic growth is an integrated, individual-based response to environmental conditions, especially in ectotherms. Growth dynamics of large, mobile animals are particularly useful as bio-indicators of environmental change at regional scales. We assembled growth rate data from throughout the West Atlantic for green turtles, Chelonia mydas, which are long-lived, highly migratory, primarily herbivorous mega-consumers that may migrate over hundreds to thousands of kilometers. Our dataset, the largest ever compiled for sea turtles, has 9690 growth increments from 30 sites from Bermuda to Uruguay from 1973 to 2015. Using generalized additive mixed models, we evaluated covariates that could affect growth rates; body size, diet, and year have significant effects on growth. Growth increases in early years until 1999, then declines by 26% to 2015. The temporal (year) effect is of particular interest because two carnivorous species of sea turtles – hawksbills, Eretmochelys imbricata, and loggerheads, Caretta caretta – exhibited similar significant declines in growth rates starting in 1997 in the West Atlantic, based on previous studies. These synchronous declines in productivity among three sea turtle species across a trophic spectrum provide strong evidence that an ecological regime shift (ERS) in the Atlantic is driving growth dynamics. The ERS resulted from a synergy of the 1997/1998 El Niño Southern Oscillation (ENSO) – the strongest on record – combined with an unprecedented warming rate over the last two to three decades. Further support is provided by the strong correlations between annualized mean growth rates of green turtles and both sea surface temperatures (SST) in the West Atlantic for years of declining growth rates (r = -0.94) and the Multivariate ENSO Index (MEI) for all years (r = 0.74). Granger-causality analysis also supports the latter finding. We discuss multiple stressors that could reinforce and prolong the effect of the ERS. This study

Ecological regime shift drives declining growth rates of sea turtles throughout the West Atlantic.

Science.gov (United States)

Bjorndal, Karen A; Bolten, Alan B; Chaloupka, Milani; Saba, Vincent S; Bellini, Cláudio; Marcovaldi, Maria A G; Santos, Armando J B; Bortolon, Luis Felipe Wurdig; Meylan, Anne B; Meylan, Peter A; Gray, Jennifer; Hardy, Robert; Brost, Beth; Bresette, Michael; Gorham, Jonathan C; Connett, Stephen; Crouchley, Barbara Van Sciver; Dawson, Mike; Hayes, Deborah; Diez, Carlos E; van Dam, Robert P; Willis, Sue; Nava, Mabel; Hart, Kristen M; Cherkiss, Michael S; Crowder, Andrew G; Pollock, Clayton; Hillis-Starr, Zandy; Muñoz Tenería, Fernando A; Herrera-Pavón, Roberto; Labrada-Martagón, Vanessa; Lorences, Armando; Negrete-Philippe, Ana; Lamont, Margaret M; Foley, Allen M; Bailey, Rhonda; Carthy, Raymond R; Scarpino, Russell; McMichael, Erin; Provancha, Jane A; Brooks, Annabelle; Jardim, Adriana; López-Mendilaharsu, Milagros; González-Paredes, Daniel; Estrades, Andrés; Fallabrino, Alejandro; Martínez-Souza, Gustavo; Vélez-Rubio, Gabriela M; Boulon, Ralf H; Collazo, Jaime A; Wershoven, Robert; Guzmán Hernández, Vicente; Stringell, Thomas B; Sanghera, Amdeep; Richardson, Peter B; Broderick, Annette C; Phillips, Quinton; Calosso, Marta; Claydon, John A B; Metz, Tasha L; Gordon, Amanda L; Landry, Andre M; Shaver, Donna J; Blumenthal, Janice; Collyer, Lucy; Godley, Brendan J; McGowan, Andrew; Witt, Matthew J; Campbell, Cathi L; Lagueux, Cynthia J; Bethel, Thomas L; Kenyon, Lory

2017-11-01

Somatic growth is an integrated, individual-based response to environmental conditions, especially in ectotherms. Growth dynamics of large, mobile animals are particularly useful as bio-indicators of environmental change at regional scales. We assembled growth rate data from throughout the West Atlantic for green turtles, Chelonia mydas, which are long-lived, highly migratory, primarily herbivorous mega-consumers that may migrate over hundreds to thousands of kilometers. Our dataset, the largest ever compiled for sea turtles, has 9690 growth increments from 30 sites from Bermuda to Uruguay from 1973 to 2015. Using generalized additive mixed models, we evaluated covariates that could affect growth rates; body size, diet, and year have significant effects on growth. Growth increases in early years until 1999, then declines by 26% to 2015. The temporal (year) effect is of particular interest because two carnivorous species of sea turtles-hawksbills, Eretmochelys imbricata, and loggerheads, Caretta caretta-exhibited similar significant declines in growth rates starting in 1997 in the West Atlantic, based on previous studies. These synchronous declines in productivity among three sea turtle species across a trophic spectrum provide strong evidence that an ecological regime shift (ERS) in the Atlantic is driving growth dynamics. The ERS resulted from a synergy of the 1997/1998 El Niño Southern Oscillation (ENSO)-the strongest on record-combined with an unprecedented warming rate over the last two to three decades. Further support is provided by the strong correlations between annualized mean growth rates of green turtles and both sea surface temperatures (SST) in the West Atlantic for years of declining growth rates (r = -.94) and the Multivariate ENSO Index (MEI) for all years (r = .74). Granger-causality analysis also supports the latter finding. We discuss multiple stressors that could reinforce and prolong the effect of the ERS. This study demonstrates the

The East Atlantic - West Russia Teleconnection in the North Atlantic: Climate Impact and Relation to Rossby Wave Propagation

Science.gov (United States)

Lim, Young-Kwon

2014-01-01

Large-scale winter teleconnection of the East Atlantic - West Russia (EA-WR) over the Atlantic and surrounding regions is examined in order to quantify its impacts on temperature and precipitation and identify the physical mechanisms responsible for its existence. A rotated empirical orthogonal function (REOF) analysis of the upper-tropospheric monthly height field captures successfully the EA-WR pattern and its interannual variation, with the North Atlantic Oscillation as the first mode. EA-WRs climate impact extends from eastern North America to Eurasia. The positive (negative) EA-WR produces positive (negative) temperature anomalies over the eastern US, western Europe and Russia east of Caspian Sea, with negative (positive) anomalies over eastern Canada, eastern Europe including Ural Mountains and the Middle East. These anomalies are largely explained by lower-tropospheric temperature advections. Positive (negative) precipitation anomalies are found over the mid-latitude Atlantic and central Russia around 60E, where lower-level cyclonic (anticyclonic) circulation anomaly is dominant. The eastern Canada and the western Europe are characterized by negative (positive) precipitation anomalies.The EA-WR is found to be closely associated with Rossby wave propagation. Wave activity fluxes show that it is strongly tied to large-scale stationary waves. Furthermore, a stationary wave model (SWM) forced with vorticity transients in the mid-latitude Atlantic (approximately 40N) or diabatic heat source over the subtropical Atlantic near the Caribbean Sea produces well-organized EA-WR-like wave patterns, respectively. Sensitivity tests with the SWM indicate improvement in the simulation of the EA-WR when the mean state is modified to have a positive NAO component that enhances upper-level westerlies between 40-60N.

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

Science.gov (United States)

Izzo, Lisa K.; Zydlewski, Joseph D.

2017-01-01

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

Atlantic Region

NARCIS (Netherlands)

Elands, B.H.M.; Bell, S.; Blok, J.

2010-01-01

Chapter 2 explores recreation and tourism practices in forest areas in the Atlantic region, which refers to the geographical area close to the North Sea and the Atlantic Ocean. The Atlantic countries described in this section are Belgium (Flanders and Wallonia), Denmark, Iceland, Ireland, the

Deep-sea benthic community and environmental impact assessment at the Atlantic Frontier

Science.gov (United States)

Gage, John D.

2001-05-01

The seabed community provides a sensitive litmus for environmental change. North Sea analysis of benthic populations provides an effective means for monitoring impacts from man's interventions, such as offshore oil exploitation and fishing, against baseline knowledge of the environment. Comparable knowledge of the benthic biology in the deep waters of the Atlantic Frontier beyond the N.E. Atlantic shelf edge is poorly developed. But uncertainties should not encourage assumptions and extrapolations from the better-known conditions on the continental shelf. While sampling at present still provides the best means to assess the health of the deepwater benthic habitat, protocols developed for deep-sea fauna should be applied. These are necessary because of (a) lower faunal densities, (b) higher species richness, (c) smaller body size, and (d) to ensure comparability with other deep-sea data. As in the North Sea, species richness and relative abundance can be analysed from quantitative samples in order to detect impacts. But analysis based on taxonomic sufficiency above species level is premature, even if arguably possible for coastal communities. Measures also need to ensure identifications are not forced to more familiar coastal species without proper study. Species-level analysis may be applied to seabed photographs of megafauna in relation to data on bottom environment, such as currents and the sediment, to monitor the health of the deep-water community. Although the composition of higher taxa in the benthic community is broadly similar to soft sediments on the shelf, concordance in sensitivities is speculative. Moreover, new organisms occur, such as giant protozoan xenophyophores, unknown on the continental shelf, whose sensitivities remain conjectural. Past knowledge of the benthic biology of the deep-water areas off Scotland is based on scattered stations and some more focussed, multidisciplinary studies, and should be significantly augmented by the results from

18th Middle Atlantic Regional Meeting, American Chemical Society

International Nuclear Information System (INIS)

Anon.

1985-01-01

The Proceedings of the 18th Middle Atlantic Regional Meeting of the American Chemical Society held May 21-23, 1984, include information about the meeting, e.g. area map and list of exhibitors, and abstracts for most of the 397 papers. A few papers are only title listed. The papers are arranged into sections dealing with analytical chemistry, biochemistry, chemical education, environmental chemistry, fuel chemistry, history of chemistry, industrial and engineering chemistry, inorganic chemistry, photochemistry, physical chemistry, polymer chemistry, and polymeric materials. Sections are also included to highlight undergraduate research and papers by chemical technicians and younger chemists. Separate abstracts have been prepared for 36 papers

The sea-level budget along the Northwest Atlantic coast : GIA, mass changes, and large-scale ocean dynamics

NARCIS (Netherlands)

Frederikse, T.; Simon, K.M.; Katsman, C.A.; Riva, R.E.M.

2017-01-01

Sea-level rise and decadal variability along the northwestern coast of the North Atlantic Ocean are studied in a self-consistent framework that takes into account the effects of solid-earth deformation and geoid changes due to large-scale mass redistribution processes. Observations of sea and

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

Science.gov (United States)

Huang, Hsiang-Wen

2015-01-01

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

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

Directory of Open Access Journals (Sweden)

Hsiang-Wen Huang

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

Oxygen isotopic composition and its application to the study of tracing oceanographical process in Bering Sea and Chukchi Sea

Institute of Scientific and Technical Information of China (English)

尹明端; 曾宪章; 曾文义; 吴世炎; 施纯坦

2002-01-01

In this paper, the 18O distribution of surface water from the central sea areas of the Bering Sea and the Chukchi Sea was studied. The δ18O value of surface water from the Bering Sea is averagely -0.5‰; the δ18O contents of the Chukchi Sea are distributionally lower in northeast and higher in southwest; the δ18O value at the margin of Canadian Basin is -2.8‰, and averagely -0.8‰ in the southern area of the Chukchi Sea. The δ18O vertical distribution in some deep water stations from the Chukchi Sea and the Bering Sea is also studied. In the southern margin of Canadian Basin, the δ18O value is -2‰ -3‰ for surface layer and rises to 0 at 100 m depth layer. In the Bering Sea, the δ18O is about -0.5‰ for surface layer and increases to 0 at the depth of 300 m. The NO tracer can reflect obviously three water masses vertically distributed in the central Bering Sea: the upper Bering water mass, the middle Bering water mass and the deep Pacific water mass. The distributive ranges of NO and temperature for the various water masses are T780 μmol/dm3 and T≥7℃, NO>650 μmol/dm3 for upper Bering water mass, T<4℃, 550middle Bering water mass, and T<4℃, 330sea bottom. Its isotopic characteristics are the same as the Atlantic water, showing that the sea water comes from the north Atlantic. The freshwater end-member of the Chukchi Sea in the survey period is also explored.

Acropora palmata reef framework: A reliable indicator of sea level in the western atlantic for the past 10,000 years

Science.gov (United States)

Lighty, R. G.; MacIntyre, I. G.; Stuckenrath, R.

1982-10-01

A minimum sea-level curve for the past 10,000 years has been constructed on the basis of radiocarbon dates of Acropora palmata (Lamarck) samples from the shallow-water framework of both relict and modern reefs of the tropical western Atlantic. A. palmata framework is a reliable reference for reconstructing the history of late Quaternary sea levels owing to its restricted depth range (palmata framework, the ease of obtaining uncontaminated samples, and the minimal compaction of A. palmata reef facies. The minimum sea-level curve constructed in this study is useful not only in evaluating the reliability of present and future Holocene sea-level curves for the western Atlantic, but also in estimating paleo-water depths in the study of Holocene reef history of this area.

The influence of the Atlantic Warm Pool on the Florida panhandle sea breeze

Science.gov (United States)

Misra, Vasubandhu; Moeller, Lauren; Stefanova, Lydia; Chan, Steven; O'Brien, James J.; Smith, Thomas J.; Plant, Nathaniel

2011-01-01

In this paper we examine the variations of the boreal summer season sea breeze circulation along the Florida panhandle coast from relatively high resolution (10 km) regional climate model integrations. The 23 year climatology (1979–2001) of the multidecadal dynamically downscaled simulations forced by the National Centers for Environmental Prediction–Department of Energy (NCEP-DOE) Reanalysis II at the lateral boundaries verify quite well with the observed climatology. The variations at diurnal and interannual time scales are also well simulated with respect to the observations. We show from composite analyses made from these downscaled simulations that sea breezes in northwestern Florida are associated with changes in the size of the Atlantic Warm Pool (AWP) on interannual time scales. In large AWP years when the North Atlantic Subtropical High becomes weaker and moves further eastward relative to the small AWP years, a large part of the southeast U.S. including Florida comes under the influence of relatively strong anomalous low-level northerly flow and large-scale subsidence consistent with the theory of the Sverdrup balance. This tends to suppress the diurnal convection over the Florida panhandle coast in large AWP years. This study is also an illustration of the benefit of dynamic downscaling in understanding the low-frequency variations of the sea breeze.

Middle Atlantic neutron therapy trail

International Nuclear Information System (INIS)

Rogers, C.

1975-01-01

A consortium of therapeutic radiologists in the Middle Atlantic States and physicists at the Naval Research Laboratory has been established to investigate the use of fast neutron beams in the control of some tumors. Many radiobiology experiments have indicated that neutron beams may have an advantage in the control of local tumors over that of conventional forms of radiotherapy. In preparation for clinical radiotherapy trials, extensive measurements have quantified the various physical characteristics of the NRL cyclotron-produced neutron beam. Techniques have been developed for the absolute determination of delivered dose at depth in tissue for this beam, accounting for the relatively small component of dose delivered by gamma rays, as well as that by the neutrons. A collimator system has been designed to allow the precise field definition necessary for optimum therapy treatment planning. A dose control and monitor unit has been engineered and has demonstrated a reproducibility of 0.2 percent. The relative biological effectiveness of this neutron bean has been studied with several biological systems to aid in determining proper radiotherapeutic dose levels. The objective of these studies is a full-scale clinical radiotherapy trial to test neutron effectiveness as compared to that of conventional radiotherapy, after a pilot study in man

Sea surface temperature and sea ice variability in the subpolar North Atlantic from explosive volcanism of the late thirteenth century

DEFF Research Database (Denmark)

Sicre, M. -A.; Khodri, M.; Mignot, J.

2013-01-01

In this study, we use IP25 and alkenone biomarker proxies to document the subdecadal variations of sea ice and sea surface temperature in the subpolar North Atlantic induced by the decadally paced explosive tropical volcanic eruptions of the second half of the thirteenth century. The short-and long......-term evolutions of both variables were investigated by cross analysis with a simulation of the IPSL-CM5A LR model. Our results show short-term ocean cooling and sea ice expansion in response to each volcanic eruption. They also highlight that the long response time of the ocean leads to cumulative surface cooling...... and subsurface heat buildup due to sea ice capping. As volcanic forcing relaxes, the surface ocean rapidly warms, likely amplified by subsurface heat, and remains almost ice free for several decades....

Inter-Relationship Between Subtropical Pacific Sea Surface Temperature, Arctic Sea Ice Concentration, and the North Atlantic Oscillation in Recent Summers and Winters

Science.gov (United States)

Lim, Young-Kwon; Cullather, Richard I.; Nowicki, Sophie M.; Kim, Kyu-Myong

2017-01-01

The inter-relationship between subtropical western-central Pacific sea surface temperatures (STWCPSST), sea ice concentration in the Beaufort Sea (SICBS), and the North Atlantic Oscillation (NAO) are investigated for the last 37 summers and winters (1980-2016). Lag-correlation of the STWCPSST×(-1) in spring with the NAO phase and SICBS in summer increases over the last two decades, reaching r = 0.4-0.5 with significance at 5 percent, while winter has strong correlations in approximately 1985-2005. Observational analysis and the atmospheric general circulation model experiments both suggest that STWCPSST warming acts to increase the Arctic geopotential height and temperature in the following season. This atmospheric response extends to Greenland, providing favorable conditions for developing the negative phase of the NAO. SIC and surface albedo tend to decrease over the Beaufort Sea in summer, linked to the positive surface net shortwave flux. Energy balance considering radiative and turbulent fluxes reveal that available energy that can heat surface is larger over the Arctic and Greenland and smaller over the south of Greenland, in response to the STWCPSST warming in spring. XXXX Arctic & Atlantic: Positive upper-level height/T anomaly over the Arctic and Greenland, and a negative anomaly over the central-eastern Atlantic, resembling the (-) phase of the NAO. Pacific: The negative height/T anomaly over the mid-latitudes, along with the positive anomaly over the STWCP, where 1degC warming above climatology is prescribed. Discussion: It is likely that the Arctic gets warm and the NAO is in the negative phase in response to the STWCP warming. But, there are other factors (e.g., internal variability) that contribute to determination of the NAO phase: not always the negative phase of the NAO in the event of STWCP warming (e.g.: recent winters and near neutral NAO in 2017 summer).

Geochemistry of Slow-Growing Corals: Reconstructing Sea Surface Temperature, Salinity and the North Atlantic Oscillation

Science.gov (United States)

2007-06-01

Number 8, October 1989) The island of Bermuda (64°W, 32°N) (Fig. 1.3) located in the western sub- tropical Atlantic is an excellent location for examining...lobata at Clipperton Atoll, Coral Reefv, 18, 13-27, 1999. Lough, J. M., A strategy to improve the contribution of coral data to high-resolution...to evaluate winter Sr/Ca. The island of Bermuda (64°W, 32°N) is located in the Sargasso Sea in the sub-tropical North Atlantic. This site is

Post-Glacial Development of Western North Atlantic - Labrador Sea Oceanographic Circulation

DEFF Research Database (Denmark)

Sheldon, Christina

2015-01-01

The subpolar North Atlantic Ocean – Labrador Sea region is an important site for both oceanographic and atmospheric circulation. The convergence of ocean currents causes downwelling of cold, saline water in the subpolar gyre, helping to drive the world-wide thermohaline circulation system. The main......, the subpolar gyre weakened, which carried less Gulf Stream-derived water to the western North Atlantic Ocean via the West Greenland Current and the Slopewater Current, south of Newfoundland. Changes in the subpolar gyre circulation had developed to be analogous to the modern climate by approximately 2 cal kyr...... surface currents involved in the gyre are the south-flowing, cold and relatively fresh Labrador Current and the north-flowing, warm and relatively saline Gulf Stream. The oceanic front between these two major currents moves north and south, dependent on the relative strengths of the currents, impacting...

The Sea Stacks Project: Enhancing the Use of Regional Literature in Atlantic Canadian Schools

Directory of Open Access Journals (Sweden)

Vivian Howard

2012-06-01

Full Text Available Research over the past two decades has amply demonstrated the importance of literature to the formation of both regional and national cultural identity, particularly in the face of mass market globalization of children’s book publishing in the 21st century as well as the predominance of non-Canadian content from television, movies, books, magazines and internet media. However, Canadian children appear to have only very limited exposure to Canadian authors and illustrators. In Atlantic Canada, regional Atlantic Canadian authors and illustrators for children receive very limited critical attention, and resources for the study and teaching of Atlantic Canadian children’s literature are few. Print and digital information sources on regional children’s books, publishing, authors and illustrators are scattered and inconsistent in quality and currency. This research project directly addresses these key concerns by summarizing the findings of a survey of Atlantic Canadian teachers on their use of regional books. In response to survey findings, the paper concludes by describing the creation of the Sea Stacks Project an authoritative web-delivered information resource devoted to contemporary Atlantic Canadian literature for children and teens.

The air-sea equilibrium and time trend of hexachlorocyclohexanes in the Atlantic Ocean between the Arctic and Antarctica.

Science.gov (United States)

Lakaschus, Sonke; Weber, Kurt; Wania, Frank; Bruhn, Regina; Schrems, Otto

2002-01-15

Hexachlorocyclohexanes (HCHs) were determined simultaneously in air and seawater during two cruises across the Atlantic Ocean between the Arctic Ocean (Ny-Alesund/ Svalbard, 79 degrees N; 12 degrees E) and the Antarctic Continent (Neumayer Station/ Ekstroem Ice Shelf, 70 degrees S; 8.2 degrees W) in 1999/ 2000. The concentrations of alpha-HCH and gamma-HCH in air and surface waters of the Arctic exceeded those in Antarctica by 1-2 orders of magnitude. The gaseous concentrations of gamma-HCH were highest above the North Sea and between 20 degrees N and 30 degrees S. Fugacity fractions were used to estimate the direction of the air-sea gas exchange. These showed for alpha-HCH thatthe measured concentrations in both phases were close to equilibrium in the North Atlantic (78 degrees N-40 degrees N), slightly undersaturated between 30 degrees N and 10 degrees S and again close to equilibrium between 20 degrees S and 50 degrees S. Y-HCH has reached phase equilibrium in the North Atlantic as alpha-HCH, but the surface waters of the tropical and southern Atlantic were strongly undersaturated with y-HCH, especially between 30 degrees N and 20 degrees S. These findings are significantly different from two earlier estimates around 1990 as a result of global emission changes within the past decade. Therefore, we investigated the time trend of the HCHs in the surface waters of the Atlantic between 50 degrees N and 60 degrees S on the basis of archived samples taken in 1987-1997 and those from 1999. A decrease of alpha-HCH by a factor of approximately 4 is observed at all sampling locations. No decrease of gamma-HCH occurred between 30 degrees N and 30 degrees S, but there was a decrease in the North Atlantic, North Sea, and in the South Atlantic south of 40 degrees S. The constant level of gamma-HCH in the tropical Atlantic confirms the conclusion that the tropical Atlantic acts as a sink for y-HCH at present time. The measured alpha-HCH seawater concentrations were compared

Atlantic Water transformation in the Nordic Seas and its influence on the export rate of the Overflow Waters

Science.gov (United States)

Garcia Quintana, Yarisbel; Wiesner, Pia; Hu, Xianmin; Myers, Paul

2017-04-01

The Nordic Seas (NS) are the main gateway between the Arctic and the Atlantic Oceans. The basin can be considered as the headwaters for the Meridional Overturning Circulation (MOC), for it is there that the Denmark Strait Overflow Water (DSOW) and the Iceland-Scotland Overflow Water (ISOW) acquire their properties. Their inflow into the North Atlantic Ocean occurs across the Greenland-Scotland ridge. Together with Labrador Sea Water, DSOW and ISOW are the main components of the North Atlantic Deep Water (NADW), which ventilates the lower limb of the Atlantic MOC. In spite recent studies exploring the export rate and later pathways of the overflows, the question about what drives them, remains. Here we explore the transformation of the Atlantic Water (AW) as it enters the NS through Denmark Strait, Iceland Faroe Ridge and Faroe Schotland Channel, as well as its pathways within the basin. To do so, we use an eddy-permitting ocean general circulation model run over the period 2002 to 2015. Two different approaches are used to track the AW transformation in the NS: the well-tested off-line Lagrangian tool ARIANE and on-line passive tracers. In both cases we use the same definition of AW to tag its inflow through the three entering sections. The overflows directly impact circulation and water properties in much of the deep Atlantic Ocean, thus a better understanding of the physical processes behind their variability is crucial a asset.

South Atlantic pale oceanography and evolution during the Albian; Paleoceanografia e a evolucao do Atlantico Sul no Albiano

Energy Technology Data Exchange (ETDEWEB)

Azevedo, Ricardo Latge Milward de [PETROBRAS, Rio de Janeiro, RJ (Brazil). Diretoria de Exploracao e Producao]. E-mail: ricardolatge@petrobras.com.

2004-11-01

A vast array of geochemical, geophysical, sedimentological and paleontological data, together with modern environmental analogues in the Red Sea, support the view that the South Atlantic maintained its bi partitioned condition from latest Aptian to the middle Albian. The lineament comprising the Florianopolis High and Sao Paulo Dorsal formed an effective barrier to sea-water circulation between the Southern South Atlantic (SSA) and Central South Atlantic (CSA) until late Albian times. During that time, the latter communicated mainly with the North Atlantic, which in turn was connected to the Tethys Sea. The CSA was then entirely located within an arid climatic belt, and subject to a negative hydric balance, whereas an estuarine circulation pattern prevailed in the SSA. The comparison of carbon and oxygen stable isotope results from limestones in various parts of the world demonstrates that the CSA waters were warmer than those of the Malvinas in the South, and the Tethyan Sea to the North. The CSA sedimentary evolution was coeval with profound paleoceanographic changes. These were mainly induced by global tectonic phenomena related to the dynamics of oceanic crustal accretion, culminating with the definitive interconnection of the Tethyan and Indian oceanic waters by the end-Albian. Halokynetic movements and orbital variations brought about oscillations in accommodation space, which permitted the stacking of tens of shallowing-upward cycles with varied magnitudes. (author)

Distribution of Polycystine Radiolarians in Bottom Surface Sediments and Its Relation to Summer Sea Temperature in the High-Latitude North Atlantic

Directory of Open Access Journals (Sweden)

Alexander Matul

2017-10-01

Full Text Available An objective of the study is to get new biogeographic information on the modern polycystine radiolarians from the high-latitude North Atlantic. The quantitative radiolarian dataset was compiled from publications and own micropaleontological counts from samples of the bottom surface sediments of the North Atlantic north of 40°N and Nordic Seas. Standard statistical treatment of micropaleontological data by factor analysis reveals five radiolarian assemblages which have their highest load at the specific temperature range in agreement with the oceanographic setting. An occurrence of radiolarian assemblages reflects extension and interaction of the warm North Atlantic and cold Polar/Arctic waters. Radiolarian distribution exhibits good correlation with the climatically averaged summer sea temperature on depth level of 200 m.

The Caspian Sea Catchment influenced by Atlantic Teleconnections in CESM1.2.2 and Observations

Science.gov (United States)

Nandini, S. D.; Prange, M.; Schulz, M.

2017-12-01

The Caspian Sea (CS) is the world's largest inland sea and located within a closed (endorheic) drainage basin [ 37°-47N, 47°-54°E]. It has undergone dynamic variations (>3 m) during the past century with huge impacts on the economy, ecosystem and livelihood of coastal people. The origin of these variations as well as future changes are disputable. Here, we examine the impact of the major seasonal North Atlantic teleconnection patterns, the North Atlantic Oscillation (NAO) and the East Atlantic pattern (EA) on Caspian hydroclimate variability from 1850-2100 CE. Five Numerical experiments at different atmospheric grid resolutions (2° and 1°) and atmospheric model versions (CAM4 and CAM5) are carried out with the coupled Community Earth System Model (CESM1.2.2). Results reveal the 1° CESM1.2.2 CAM5 captures DJF NAO (46.5%) and EA (13.4%), agreeing well with observational data (1850-2000). The DJF NAO has a strong influence on the DJF temperature, rainfall and evaporation minus precipitation (E-P) over the Caspian sub-basins (Volga, Ural, Terek and Kura). Furthermore, 1° model climate projections (2020-2100 CE) are performed with different Representative Concentration Pathways (RCP4.5 and RCP8.5) to examine likely changes in the NAO and EA and their influence on the Caspian catchment. The NAO under the RCP4.5 and RCP8.5 scenarios remains the leading mode with the highest variance and influences E-P with increased precipitation over the Volga basin and increased evaporation over the Caspian Sea. The above canceling effects act on the hydroclimate variability in the Caspian sub-basins. Moreover, it is indicated that no substantial change is predicted in the CSL by the year 2100. Keywords: North Atlantic Oscillation (NAO), CESM1.2.2 resolutions, Evaporation minus Precipitation (E-P), RCP4.5, RCP8.5

Nematocarcinus Milne Edwards, 1881 (Crustacea, Decapoda) from Southwestern Atlantic, including the Southern Mid-Atlantic Ridge area.

Science.gov (United States)

Cardoso, Irene A; Burukovsky, Rudolf N

2014-11-26

The deep sea shrimp genus Nematocarcinus Milne Edwards, 1881 includes 47 species, ten of them have been recorded from the Atlantic Ocean. Herein, material sampled during three scientific projects (REVIZEE Central Fishery project; Campos Basin Deep Sea Environmental Project; Evaluation of Environmental Heterogeneity in the Campos Basin) made in the Southwestern Atlantic, off Brazil, is examined. In addition, material sampled from the South Mid Atlantic Ridge (MAR-ECO Project) was also examined. Four species are recorded for the first time to the southwestern Atlantic Ocean including Mid Atlantic Ridge area: Nematocarcinus faxoni Burukovsky, 2001; N. gracilipes Filhol, 1884; N. rotundus Crosnier & Forest, 1973 and N. tenuipes Spence-Bate, 1888.

Importance of flexure in response to sedimentation and erosion along the US Atlantic passive margin in reconciling sea level change and paleoshorelines

Science.gov (United States)

Moucha, R.; Ruetenik, G.; de Boer, B.

2017-12-01

Reconciling elevations of paleoshorelines along the US Atlantic passive margin with estimates of eustatic sea level have long posed to be a challenge. Discrepancies between shoreline elevation and sea level have been attributed to combinations of tectonics, glacial isostatic adjustment, mantle convection, gravitation and/or errors, for example, in the inference of eustatic sea level from the marine 18O record. Herein we present a numerical model of landscape evolution combined with sea level change and solid Earth deformations to demonstrate the importance of flexural effects in response to erosion and sedimentation along the US Atlantic passive margin. We quantify these effects using two different temporal models. One reconciles the Orangeburg scarp, a well-documented 3.5 million-year-old mid-Pliocene shoreline, with a 15 m mid-Pliocene sea level above present-day (Moucha and Ruetenik, 2017). The other model focuses on the evolution of the South Carolina and northern Georgia margin since MIS 11 ( 400 Ka) using a fully coupled ice sheet, sea level and solid Earth model (de Boer et al, 2014) while relating our results to a series of enigmatic sea level high stand markers. de Boer, B., Stocci, P., and van de Wal, R. (2014). A fully coupled 3-d ice-sheet-sea-level model: algorithm and applications. Geoscientific Model Development, 7:2141-2156. Moucha, R. and Ruetenik, G. A. (2017). Interplay between dynamic topography and flexure along the US Atlantic passive margin: Insights from landscape evolution modeling. Global and Planetary Change, 149: 72-78

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

Science.gov (United States)

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

2011-01-01

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

Aspects of Remote Sensing in the GEOid and Sea level Of the North Atlantic Region (GEOSONAR) Project

DEFF Research Database (Denmark)

Hilger, Klaus Baggesen; Nielsen, Allan Aasbjerg; Knudsen, Per

1999-01-01

The general objectives of the GEOid and Sea level Of the North Atlantic Region (GEOSONAR) project are presented. These include analyses of the dynamics of the ocean and its characteristics. The analyses are mainly based on remote sensing. As an example a data set obtained by the multi-channel Sea-viewing...... Wide Field-of-view Sensor (SeaWiFs) is analysed. The presentation results include the computed principal components (PC) and the maximum autocorrelation factors (MAF). Both methods are expected to be incorporated into future analyses of the state of the ocean....

PBDEs in the atmosphere over the Asian marginal seas, and the Indian and Atlantic oceans

Science.gov (United States)

Li, Jun; Li, Qilu; Gioia, Rosalinda; Zhang, Yanlin; Zhang, Gan; Li, Xiangdong; Spiro, Baruch; Bhatia, Ravinder S.; Jones, Kevin C.

2011-12-01

Air samples were collected from Jan 16 to Mar 14, 2008 onboard the Oceanic II- The Scholar Ship which navigated an east-west transect from Shanghai to Cape Verde, and polybrominated diphenyl ethers (PBDEs) were analyzed in these samples. PBDE concentrations in the atmosphere over the open seas were influenced by proximity to source areas and land, and air mass origins. The concentrations of Σ 21PBDEs over the East and South China Seas, the Bay of Bengal and the Andaman Sea, the Indian Ocean, and the Atlantic Ocean were 10.8 ± 6.13, 3.22 ± 1.57, 5.12 ± 3.56, and 2.87 ± 1.81 pg m -3, respectively. BDE-47 and -99 were the dominant congeners in all the samples, suggesting that the widely used commercial penta-BDE products were the original sources. Over some parts of Atlantic and Indian Ocean, daytime concentrations of BDE-47 and BDE-99 were higher than the concentrations at night. The strong atmospheric variability does not always coincide with a diurnal cycle, but the variability in air concentrations in such remote areas of the ocean remains strong. No significant trends were found for each of PBDE congener with latitude.

Contrasting records of sea-level change in the eastern and western North Atlantic during the last 300 years

Science.gov (United States)

Long, A. J.; Barlow, N. L. M.; Gehrels, W. R.; Saher, M. H.; Woodworth, P. L.; Scaife, R. G.; Brain, M. J.; Cahill, N.

2014-02-01

We present a new 300-year sea-level reconstruction from a salt marsh on the Isle of Wight (central English Channel, UK) that we compare to other salt-marsh and long tide-gauge records to examine spatial and temporal variability in sea-level change in the North Atlantic. Our new reconstruction identifies an overall rise in relative sea level (RSL) of c. 0.30 m since the start of the eighteenth century at a rate of 0.9±0.3 mm yr. Error-in-variables changepoint analysis indicates that there is no statistically significant deviation from a constant rate within the dataset. The reconstruction is broadly comparable to other tide-gauge and salt-marsh records from the European Atlantic, demonstrating coherence in sea level in this region over the last 150-300 years. In contrast, we identify significant differences in the rate and timing of RSL with records from the east coast of North America. The absence of a strong late 19th/early 20th century RSL acceleration contrasts with that recorded in salt marsh sediments along the eastern USA coastline, in particular in a well-dated and precise sea-level reconstruction from North Carolina. This suggests that this part of the North Carolina sea level record represents a regionally specific sea level acceleration. This is significant because the North Carolina record has been used as if it were globally representative within semi-empirical parameterisations of past and future sea-level change. We conclude that regional-scale differences of sea-level change highlight the value of using several, regionally representative RSL records when calibrating and testing semi-empirical models of sea level against palaeo-records. This is because by using records that potentially over-estimate sea-level rise in the past such models risk over-estimating sea-level rise in the future.

Influence of Atlantic SST anomalies on the atmospheric circulation in the Atlantic-European sector

Directory of Open Access Journals (Sweden)

E. Kestenare

2003-06-01

Full Text Available Recent studies of observational data suggest that Sea Surface Temperature (SST anomalies in the Atlantic Ocean have a significant influence on the atmospheric circulation in the Atlantic-European sector in early winter and in spring. After reviewing this work and showing that the spring signal is part of a global air-sea interaction, we analyze for comparison an ensemble of simulations with the ECHAM4 atmospheric general circulation model in T42 resolution forced by the observed distribution of SST and sea ice, and a simulation with the ECHAM4/OPA8 coupled model in T30 resolution. In the two cases, a significant influence of the Atlantic on the atmosphere is detected in the Atlantic-European sector. In the forced mode, ECHAM4 responds to SST anomalies from early spring to late summer, and also in early winter. The forcing involves SST anomalies not only in the tropical Atlantic, but also in the whole tropical band, suggesting a strong ENSO influence. The modeled signal resembles that seen in the observations in spring, but not in early winter. In the coupled mode, the Atlantic SST only has a significant influence on the atmosphere in summer. Although the SST anomaly is confined to the Atlantic, the summer signal shows some similarity with that seen in the forced simulations. However, there is no counterpart in the observations.

Fish Species in a Changing World: The Route and Timing of Species Migration between Tropical and Temperate Ecosystems in Eastern Atlantic.

Directory of Open Access Journals (Sweden)

Awaluddin Halirin Kaimuddin

2016-09-01

Full Text Available The presence of tropical species has been reported in Atlantic-European waters with increasing frequency in recent years. Unfortunately, the history of their migrations is not well understood. In this study, we examined the routes and timing of fish migrations in several ecosystems of the East Atlantic Ocean, combining several publicly available and unpublicized datasets on species occurrences. The species studied were those noted as exotic or rare outside their previous known area of distribution. We used sea surface temperature (SST data obtained from 30 years of satellite observation to define three distinct time periods. Within these periods, temperature trends were studied in six ecosystems: the North Sea, the Celtic Sea, the South European Atlantic Waters, the Mediterranean Sea, the Canary Current and the Guinea Current. We also incorporated bathymetry data to describe the distribution of species. Measurement across a relatively large spatial extent was made possible by incorporating the capabilities of GIS.While SST increased consistently over time in all of the ecosystems observed, the change in number of species differed among ecosystems. The number of species in the middle regions, such as the South European Atlantic Shelf and the Western Mediterranean Sea, tended to increase over time. These regions received numbers of species from the lower or the upper latitudes according to season. Of all of the species observed in the recent period, 7 species from the Canary Current tended to be found in the Western Mediterranean Sea, and 6 species from these two regions extended their distributions to the South European Atlantic Shelf. Twelve species from the Canary Current moved seasonally to the Guinea Current. In the northern regions, 13 species moved seasonally in the North Sea and the Celtic Seas, and 12 of these species reached the South European Atlantic Shelf.This study presents a picture of routes and timing of species migration at the

The distribution of deep-sea sponge aggregations in the North Atlantic and implications for their effective spatial management

Science.gov (United States)

Howell, Kerry-Louise; Piechaud, Nils; Downie, Anna-Leena; Kenny, Andrew

2016-09-01

Sponge aggregations have been recognised as key component of shallow benthic ecosystems providing several important functional roles including habitat building and nutrient recycling. Within the deep-sea ecosystem, sponge aggregations may be extensive and available evidence suggests they may also play important functional roles, however data on their ecology, extent and distribution in the North Atlantic is lacking, hampering conservation efforts. In this study, we used Maximum Entropy Modelling and presence data for two deep-sea sponge aggregation types, Pheronema carpenteri aggregations and ostur aggregations dominated by geodid sponges, to address the following questions: 1) What environmental factors drive the broad-scale distribution of these selected sponge grounds? 2) What is the predicted distribution of these grounds in the northern North Atlantic, Norwegian and Barents Sea? 3) How are these sponge grounds distributed between Exclusive Economic Zones (EEZs) and High Seas areas? 4) What percentage of these grounds in High Seas areas are protected by the current High Seas MPA network? Our results suggest that silicate concentration, temperature, depth and amount of particulate organic carbon are the most important drivers of sponge distribution. Most of the sponge grounds are located within national EEZs rather than in the High Seas. Coordinated conservation planning between nations with significant areas of sponge grounds such as Iceland, Greenland and Faroes (Denmark), Norway (coastal Norway and Svalbard), Portugal and the UK, should be implemented in order to effectively manage these communities in view of the increasing level of human activity within the deep-sea environment.

Oceanic fronts in the Sargasso Sea control the early life and drift of Atlantic eels

DEFF Research Database (Denmark)

Munk, Peter; Hansen, Michael Møller; Maas, Gregory E.

2010-01-01

Anguillid freshwater eels show remarkable life histories. In the Atlantic, the European eel (Anguilla anguilla) and American eel (Anguilla rostrata) undertake extensive migrations to spawn in the oceanic Sargasso Sea, and subsequently the offspring drift to foraging areas in Europe and North......, during a field expedition to the eel spawning sites in the Sargasso Sea, we carried out a wide range of dedicated bio-physical studies across areas of eel larval distribution. Our findings suggest a key role of oceanic frontal processes, retaining eel larvae within a zone of enhanced feeding conditions...

77 FR 28305 - Temporary Rule To Delay Start Date of 2012-2013 South Atlantic Black Sea Bass Commercial Fishing...

Science.gov (United States)

2012-05-14

.... 120501426-2426-01] RIN 0648-BB98 Temporary Rule To Delay Start Date of 2012-2013 South Atlantic Black Sea... this temporary rule to delay the start date of the 2012-2013 fishing season for the commercial black... temporary rule delays the start date of the 2012-2013 commercial fishing season for black sea bass from June...

Horizontal and vertical distribution of Chaetognatha in the upper 1000 m of the western Sargasso Sea and the Central and South-east Atlantic.

Digital Repository Service at National Institute of Oceanography (India)

Pierrot-Bultsa, A.C.; Nair, V.R.

The chaetognath abundance, species richness and bathymetric distribution in the upper 1000 m in two regions of the Atlantic Ocean is discussed based on samples collected on two cruises, one to the Sargasso Sea (Northwest Atlantic) on board the R/V R...

Potential for shoreline changes due to sea-level rise along the U.S. mid-Atlantic region

Science.gov (United States)

Gutierrez, Benjamin T.; Williams, S. Jeffress; Thieler, E. Robert

2007-01-01

Sea-level rise over the next century is expected to contribute significantly to physical changes along open-ocean shorelines. Predicting the form and magnitude of coastal changes is important for understanding the impacts to humans and the environment. Presently, the ability to predict coastal changes is limited by the scientific understanding of the many variables and processes involved in coastal change, and the lack of consensus regarding the validity of existing conceptual, analytical, or numerical models. In order to assess potential future coastal changes in the mid-Atlantic U.S. for the U.S. Climate Change Science Program (CCSP), a workshop was convened by the U.S. Geological Survey. Assessments of future coastal change were made by a committee of coastal scientists with extensive professional experience in the mid-Atlantic region. Thirteen scientists convened for a two-day meeting to exchange information and develop a consensus opinion on potential future coastal changes for the mid-Atlantic coast in response to sea-level rise. Using criteria defined in past work, the mid-Atlantic coast was divided into four geomorphic compartments: spits, headlands, wave-dominated barriers, and mixed-energy barriers. A range of potential coastal responses was identified for each compartment based on four sea-level rise scenarios. The four scenarios were based on the assumptions that: a) the long-term sea-level rise rate observed over the 20th century would persist over the 21st century, b) the 20th century rate would increase by 2 mm/yr, c) the 20th century rate would increase by 7 mm/yr, or d) sea-level would rise by 2 m over the next few hundred years. Potential responses to these sea-level rise scenarios depend on the landforms that occur within a region and include increased likelihood for erosion and shoreline retreat for all coastal types, increased likelihood for erosion, overwash and inlet breaching for barrier islands, as well as the possibility of a threshold

Holocene North Atlantic Overturning in an atmosphere-ocean-sea-ice model compared to proxy-based reconstructions

NARCIS (Netherlands)

Blaschek, M.; Renssen, H.; Kissel, C.; Thornalley, D.

2015-01-01

Climate and ocean circulation in the North Atlantic region changed over the course of the Holocene, partly because of disintegrating ice sheets and partly because of an orbital-induced insolation trend. In the Nordic Seas, this impact was accompanied by a rather small, but significant, amount of

76 FR 23940 - Fisheries of the Northeastern United States; Atlantic Sea Scallop Fishery; Framework Adjustment 22

Science.gov (United States)

2011-04-29

... the LA fleet, Amendment 15 proposes a management uncertainty buffer based on the F associated with a... to implement Framework Adjustment 22 (Framework 22) to the Atlantic Sea Scallop Fishery Management Plan (FMP), which was developed and adopted by the New England Fishery Management Council (Council) and...

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%.

Influence of Tropical South Atlantic Sea Surface Temperatures on the Indian Summer monsoon in CMIP5 models

Science.gov (United States)

Kucharski, Fred; Joshi, Manish K.

2017-04-01

In this study the teleconnection from the tropical south Atlantic to the Indian monsoon has been assessed in observations and in 32 models from the World Climate Research Program (WCRP) Coupled Model Intercomparison Project Phase 5 (CMIP5). All models show that the regression pattern of tropics-wide Atlantic sea surface temperature (SST) anomalies onto the tropical south Atlantic index correlates well with that in observations, even though with varying spatial standard deviations. However, only about half of the 32 models considered show the correct sign of rainfall response over India to a warm anomaly in the south tropical Atlantic, which is a reduction of rainfall. On the other hand, models generally do show large-scale responses broadly consistent with the observations, and the signal over India depends on relatively subtle changes in the response. This response to a tropical south Atlantic warm (cold) anomaly is a low-level quadrupole in streamfunction with an anticyclonic (cyclonic) anomaly over the Arabian Sea and India. This anticyclonic (cyclonic) anomaly leads to a weakening (strengthening) of the Somali jet and low-level divergence (convergence) over India, both inducing a reduction (increase) of Indian rainfall. The models which do not show the correct rainfall response over India also show a response similar to the one indicated above, but with maximum of the anticyclonic (cyclonic) response shifted to the western Pacific. The large-scale Walker circulation adjustment to the tropical south Atlantic SST anomalies is identified as one of the factors which account for the differences in the low-level streamfunction response. Models (and the observations) with the correct sign of the rainfall signal over India show the dominant upper-level convergence (divergence) as response to a warm (cold) tropical south Atlantic in the western Pacific region, whereas models with the wrong sign of the rainfall signal show it predominantly in the central-eastern Pacific

Temperature, salinity, oxygen and nutrients bottle and CTD data collected in the northern North Atlantic, Nordic and Arctic Seas from 1901 to 2011 (NODC Accession 0105532)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Historical temperature, salinity, oxygen and nutrients bottle and CTD data collected in the Arctic Ocean, Barents Sea, Greenland Sea, Kara Sea, North Atlantic Ocean,...

Development of the Wintertime Sr/Ca-SST Record from Red Sea Corals as a Proxy for the North Atlantic Oscillation

Science.gov (United States)

Bernstein, W. N.; Hughen, K. A.

2009-12-01

The North Atlantic Oscillation (NAO) is one of the most pronounced and influential patterns in winter atmospheric circulation variability. This meridional redistribution of atmospheric mass across the Atlantic Ocean produces large changes in the intensity, number and direction of storms generated within the basin, and the regional climate of surrounding continents. The NAO exerts a significant impact on society, through influences on agriculture, fisheries, water management, energy generation and coastal development. NAO effects on climate extend from eastern North America across Europe to the eastern Mediterranean and Middle East. Changes in NAO behavior during the late 20th century have been linked to global warming; yet despite its importance, the causes and long-term patterns of NAO variability in the past remain poorly understood. In order to better predict the influence of the NAO on climate in the future, it is critical to examine multi-century NAO variability. The Red Sea is an excellent location from which to generate long NAO records for two reasons. First, patterns of wintertime sea surface temperature (SST) and salinity (SSS) in the Red Sea are highly correlated with NAO variability (Visbeck et al. 2001; Hurrell et al. 2003). Second, the tropical/subtropical Red Sea region contains fast growing long-lived massive Porites spp. corals with annually banded skeletons. These corals are ideal for generating well-dated high-resolution paleoclimatic records that extend well beyond the instrumental period. Here we present a study of winter SST and NAO variability in the Red sea region based on coral Sr/Ca data. In 2008, we collected multiple drill cores ranging in length from 1 to 4.1 meters from Porites corals at six sites spanning a large SST gradient. Sr/Ca measurements from multiple corals will be regressed against 23 years of satellite SST data, expanding the SST range over which we calibrate. A sampling resolution of 0.5mm will yield greater than bi

Hierarchical modeling of bycatch rates of sea turtles in the western North Atlantic

Science.gov (United States)

Gardner, B.; Sullivan, P.J.; Epperly, S.; Morreale, S.J.

2008-01-01

Previous studies indicate that the locations of the endangered loggerhead Caretta caretta and critically endangered leatherback Dermochelys coriacea sea turtles are influenced by water temperatures, and that incidental catch rates in the pelagic longline fishery vary by region. We present a Bayesian hierarchical model to examine the effects of environmental variables, including water temperature, on the number of sea turtles captured in the US pelagic longline fishery in the western North Atlantic. The modeling structure is highly flexible, utilizes a Bayesian model selection technique, and is fully implemented in the software program WinBUGS. The number of sea turtles captured is modeled as a zero-inflated Poisson distribution and the model incorporates fixed effects to examine region-specific differences in the parameter estimates. Results indicate that water temperature, region, bottom depth, and target species are all significant predictors of the number of loggerhead sea turtles captured. For leatherback sea turtles, the model with only target species had the most posterior model weight, though a re-parameterization of the model indicates that temperature influences the zero-inflation parameter. The relationship between the number of sea turtles captured and the variables of interest all varied by region. This suggests that management decisions aimed at reducing sea turtle bycatch may be more effective if they are spatially explicit. ?? Inter-Research 2008.

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

Science.gov (United States)

Toggweiler, J. R.

2010-12-01

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

TOPAZ4: an ocean-sea ice data assimilation system for the North Atlantic and Arctic

Directory of Open Access Journals (Sweden)

P. Sakov

2012-08-01

Full Text Available We present a detailed description of TOPAZ4, the latest version of TOPAZ – a coupled ocean-sea ice data assimilation system for the North Atlantic Ocean and Arctic. It is the only operational, large-scale ocean data assimilation system that uses the ensemble Kalman filter. This means that TOPAZ features a time-evolving, state-dependent estimate of the state error covariance. Based on results from the pilot MyOcean reanalysis for 2003–2008, we demonstrate that TOPAZ4 produces a realistic estimate of the ocean circulation in the North Atlantic and the sea-ice variability in the Arctic. We find that the ensemble spread for temperature and sea-level remains fairly constant throughout the reanalysis demonstrating that the data assimilation system is robust to ensemble collapse. Moreover, the ensemble spread for ice concentration is well correlated with the actual errors. This indicates that the ensemble statistics provide reliable state-dependent error estimates – a feature that is unique to ensemble-based data assimilation systems. We demonstrate that the quality of the reanalysis changes when different sea surface temperature products are assimilated, or when in-situ profiles below the ice in the Arctic Ocean are assimilated. We find that data assimilation improves the match to independent observations compared to a free model. Improvements are particularly noticeable for ice thickness, salinity in the Arctic, and temperature in the Fram Strait, but not for transport estimates or underwater temperature. At the same time, the pilot reanalysis has revealed several flaws in the system that have degraded its performance. Finally, we show that a simple bias estimation scheme can effectively detect the seasonal or constant bias in temperature and sea-level.

Diversity, distribution and nature of faunal associations with deep-sea pennatulacean corals in the Northwest Atlantic.

Directory of Open Access Journals (Sweden)

Sandrine Baillon

Full Text Available Anthoptilum grandiflorum and Halipteris finmarchica are two deep-sea corals (Octocorallia: Pennatulacea common on soft bottoms in the North Atlantic where they are believed to act as biogenic habitat. The former also has a worldwide distribution. To assist conservation efforts, this study examines spatial and temporal patterns in the abundance, diversity, and nature of their faunal associates. A total of 14 species were found on A. grandiflorum and 6 species on H. finmarchica during a multi-year and multi-site sampling campaign in eastern Canada. Among those, 7 and 5 species, respectively, were attached to the sea pens and categorized as close associates or symbionts. Rarefaction analyses suggest that the most common associates of both sea pens have been sampled. Biodiversity associated with each sea pen is analyzed according to season, depth and region using either close associates or the broader collection of species. Associated biodiversity generally increases from northern to southern locations and does not vary with depth (∼ 100-1400 m. Seasonal patterns in A. grandiflorum show higher biodiversity during spring/summer due to the transient presence of early life stages of fishes and shrimps whereas it peaks in fall for H. finmarchica. Two distinct endoparasitic species of highly modified copepods (families Lamippidae and Corallovexiidae commonly occur in the polyps of A. grandiflorum and H. finmarchica, and a commensal sea anemone frequently associates with H. finmarchica. Stable isotope analyses (δ(13C and δ(15N reveal potential trophic interactions between the parasites and their hosts. Overall, the diversity of obligate/permanent associates of sea pens is moderate; however the presence of mobile/transient associates highlights an ecological role that has yet to be fully elucidated and supports their key contribution to the enhancement of biodiversity in the Northwest Atlantic.

A field efficacy evaluation of emamectin benzoate for the control of sea lice on Atlantic salmon.

Science.gov (United States)

Armstrong, R; MacPhee, D; Katz, T; Endris, R

2000-08-01

This study evaluated the efficacy of emamectin benzoate, 0.2% aquaculture premix, against sea lice on Atlantic salmon in eastern Canada. Salmon pens received either emamectin benzoate, orally, in feed at 50 micrograms/kg body weight/day for 7 consecutive days, or the same diet with no added medication. The site veterinarian had the option of administering a bath treatment with azamethiphos to any pen in the trial. The mean number of lice per fish was lower (P emamectin benzoate was palatable and highly effective for control of sea lice on salmon.

Simulated North Atlantic-Nordic Seas water mass exchanges in an isopycnic coordinate OGCM

OpenAIRE

Nilsen, Jan Even Øie; Gao, Yongqi; Drange, Helge; Furevik, Tore; Bentsen, Mats

2003-01-01

The variability in the volume exchanges between the North Atlantic and the Nordic Seas during the last 50 years is investigated using a synoptic forced, global version of the Miami Isopycnic Coordinate Ocean Model (MICOM). The simulated volume fluxes agree with the existing observations. The net volume flux across the Faroe-Shetland Channel (FSC) is positively correlated with the net flux through the Denmark Strait (DS; R = 0.74 for 3 years low pass filtering), but negatively correlated with ...

Sea-water/groundwater interactions along a small catchment of the European Atlantic coast

International Nuclear Information System (INIS)

Einsiedl, Florian

2012-01-01

The geochemistry and isotopic composition of a karstic coastal aquifer in western Ireland has shed light on the effect of sea-water/groundwater interactions on the water quality of Ireland’s Atlantic coastal zone. The use of stable isotope data from the IAEA precipitation station in Valentia, located in SW Ireland has facilitated the characterization of groundwater recharge conditions in the western part of Ireland and suggests that groundwater is mostly replenished by the isotopically light winter precipitation. The dissolved SO 4 2- in the karstic groundwater that was collected during baseflow conditions with δ 34 S values between 4.6‰ and 18‰ may be composed of S stemming from three principal sources: SO 4 2- derived from precipitation which is composed of both sea-spray S (δ 34 S: 20‰) and an isotopically light anthropogenic source (δ 34 S: 1–5‰), SO 4 2- stemming from animal slurries (δ 34 S: ∼5‰), and intruding sea-water SO 4 2- (δ 34 S: 20.2‰). The isotopic composition of δ 18 O in dissolved groundwater SO 4 2- collected during baseflow conditions is interpreted as reflecting sea-water intrusion to the karstic coastal groundwater system. The highest δ 18 O values in dissolved groundwater SO 4 2- were in samples collected near the coast (4.8 ± 0.4‰) and the lowest (2 ± 0.5‰) were collected further inland. The δ 15 N and δ 18 O values of groundwater NO 3 - were between 3.4‰ and 11.4‰ and approximately 7.7‰, respectively, and reflect geochemical conditions in the aquifer that do not promote attenuation of NO 3 - through denitrification. As a result N loading to Kinvara Bay that is controlled by submarine groundwater discharge (SGD) was calculated as 5 tons/day on average compared to an estimated N-input that derives from precipitation of approximately 2.5 tons/a. SGD into the bay may result in near coastal sea-water quality changes. These results represent one of the first studies addressing the effect of groundwater

The North Atlantic Oscillation and sea surface temperature affect loggerhead abundance around the Strait of Gibraltar

Directory of Open Access Journals (Sweden)

José C. Báez

2011-04-01

Full Text Available The aim of this study was to explore the possible link between variations in the North Atlantic Oscillation (NAO and sea surface temperature (SST and the abundance of loggerhead turtles around the Strait of Gibraltar, using stranding data for the Andalusian coastal area as a proxy for abundance. The annual average SST (from November to October in the Gulf of Cadiz was negatively associated with the total number of loggerhead strandings each year from November 1997 to October 2006 in the Gulf of Cadiz and the Alboran Sea. The average NAO index was positively associated with the number of strandings in the Gulf of Cadiz in the following year. Prevailing westerly winds during positive NAO phases and the subsequent delayed decrease in SST may lead to turtles from the west Atlantic accumulating in the Gulf of Cadiz and unsuccessfully attempting to return. Secondary causes, such as buoyancy, cold stunning, longline fisheries, net fisheries, debilitated turtle syndrome, and trauma may also increase the number of turtle strandings.

Regional Effects of the Mount Pinatubo Eruption on the Middle East and the Red Sea

KAUST Repository

Osipov, Sergey

2017-10-26

The 1991 eruption of Mount Pinatubo had dramatic effects on the regional climate in the Middle East. Though acknowledged, these effects have not been thoroughly studied. To fill this gap and to advance understanding of the mechanisms that control variability in the Middle East\\'s regional climate, we simulated the impact of the 1991 Pinatubo eruption using a regional coupled ocean-atmosphere modeling system set for the Middle East and North Africa (MENA) domain. We used the Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) framework, which couples the Weather Research and Forecasting Model (WRF) model with the Regional Oceanic Modeling System (ROMS). We modified the WRF model to account for the radiative effect of volcanic aerosols. Our coupled ocean-atmosphere simulations verified by available observations revealed strong perturbations in the energy balance of the Red Sea, which drove thermal and circulation responses. Our modeling approach allowed us to separate changes in the atmospheric circulation caused by the impact of the volcano from direct regional radiative cooling from volcanic aerosols. The atmospheric circulation effect was significantly stronger than the direct volcanic aerosols effect. We found that the Red Sea response to the Pinatubo eruption was stronger and qualitatively different from that of the global ocean system. Our results suggest that major volcanic eruptions significantly affect the climate in the Middle East and the Red Sea and should be carefully taken into account in assessments of long-term climate variability and warming trends in MENA and the Red Sea.

Regional Effects of the Mount Pinatubo Eruption on the Middle East and the Red Sea

Science.gov (United States)

Osipov, Sergey; Stenchikov, Georgiy

2017-11-01

The 1991 eruption of Mount Pinatubo had dramatic effects on the regional climate in the Middle East. Though acknowledged, these effects have not been thoroughly studied. To fill this gap and to advance understanding of the mechanisms that control variability in the Middle East's regional climate, we simulated the impact of the 1991 Pinatubo eruption using a regional coupled ocean-atmosphere modeling system set for the Middle East and North Africa (MENA) domain. We used the Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) framework, which couples the Weather Research and Forecasting Model (WRF) model with the Regional Oceanic Modeling System (ROMS). We modified the WRF model to account for the radiative effect of volcanic aerosols. Our coupled ocean-atmosphere simulations verified by available observations revealed strong perturbations in the energy balance of the Red Sea, which drove thermal and circulation responses. Our modeling approach allowed us to separate changes in the atmospheric circulation caused by the impact of the volcano from direct regional radiative cooling from volcanic aerosols. The atmospheric circulation effect was significantly stronger than the direct volcanic aerosols effect. We found that the Red Sea response to the Pinatubo eruption was stronger and qualitatively different from that of the global ocean system. Our results suggest that major volcanic eruptions significantly affect the climate in the Middle East and the Red Sea and should be carefully taken into account in assessments of long-term climate variability and warming trends in MENA and the Red Sea.

Data-adaptive harmonic analysis and prediction of sea level change in North Atlantic region

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Kondrashov, D. A.; Chekroun, M.

2017-12-01

This study aims to characterize North Atlantic sea level variability across the temporal and spatial scales. We apply recently developed data-adaptive Harmonic Decomposition (DAH) and Multilayer Stuart-Landau Models (MSLM) stochastic modeling techniques [Chekroun and Kondrashov, 2017] to monthly 1993-2017 dataset of Combined TOPEX/Poseidon, Jason-1 and Jason-2/OSTM altimetry fields over North Atlantic region. The key numerical feature of the DAH relies on the eigendecomposition of a matrix constructed from time-lagged spatial cross-correlations. In particular, eigenmodes form an orthogonal set of oscillating data-adaptive harmonic modes (DAHMs) that come in pairs and in exact phase quadrature for a given temporal frequency. Furthermore, the pairs of data-adaptive harmonic coefficients (DAHCs), obtained by projecting the dataset onto associated DAHMs, can be very efficiently modeled by a universal parametric family of simple nonlinear stochastic models - coupled Stuart-Landau oscillators stacked per frequency, and synchronized across different frequencies by the stochastic forcing. Despite the short record of altimetry dataset, developed DAH-MSLM model provides for skillful prediction of key dynamical and statistical features of sea level variability. References M. D. Chekroun and D. Kondrashov, Data-adaptive harmonic spectra and multilayer Stuart-Landau models. HAL preprint, 2017, https://hal.archives-ouvertes.fr/hal-01537797

Algorithm Development and Validation for Satellite-Derived Distributions of DOC and CDOM in the US Middle Atlantic Bight

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Mannino, Antonio; Russ, Mary E.; Hooker, Stanford B.

2007-01-01

In coastal ocean waters, distributions of dissolved organic carbon (DOC) and chromophoric dissolved organic matter (CDOM) vary seasonally and interannually due to multiple source inputs and removal processes. We conducted several oceanographic cruises within the continental margin of the U.S. Middle Atlantic Bight (MAB) to collect field measurements in order to develop algorithms to retrieve CDOM and DOC from NASA's MODIS-Aqua and SeaWiFS satellite sensors. In order to develop empirical algorithms for CDOM and DOC, we correlated the CDOM absorption coefficient (a(sub cdom)) with in situ radiometry (remote sensing reflectance, Rrs, band ratios) and then correlated DOC to Rrs band ratios through the CDOM to DOC relationships. Our validation analyses demonstrate successful retrieval of DOC and CDOM from coastal ocean waters using the MODIS-Aqua and SeaWiFS satellite sensors with mean absolute percent differences from field measurements of cdom)(355)1,6 % for a(sub cdom)(443), and 12% for the CDOM spectral slope. To our knowledge, the algorithms presented here represent the first validated algorithms for satellite retrieval of a(sub cdom) DOC, and CDOM spectral slope in the coastal ocean. The satellite-derived DOC and a(sub cdom) products demonstrate the seasonal net ecosystem production of DOC and photooxidation of CDOM from spring to fall. With accurate satellite retrievals of CDOM and DOC, we will be able to apply satellite observations to investigate interannual and decadal-scale variability in surface CDOM and DOC within continental margins and monitor impacts of climate change and anthropogenic activities on coastal ecosystems.

Marketing Strategies Used to Promote Master of Business Administration Programs in Colleges and Universities in the Middle Atlantic Region.

Science.gov (United States)

Sable, Paul F.

Enrollments in Masters of Business Administration (MBA) programs and the use and effectiveness of marketing techniques for managing MBA enrollments were investigated in 1984. A 94-item questionnaire completed by 56 MBA programs offered at colleges and universities in the Middle Atlantic States addressed administration, awareness of marketing and…

Patagonian and southern South Atlantic view of Holocene climate

Science.gov (United States)

Kaplan, M. R.; Schaefer, J. M.; Strelin, J. A.; Denton, G. H.; Anderson, R. F.; Vandergoes, M. J.; Finkel, R. C.; Schwartz, R.; Travis, S. G.; Garcia, J. L.; Martini, M. A.; Nielsen, S. H. H.

2016-06-01

We present a comprehensive 10Be chronology for Holocene moraines in the Lago Argentino basin, on the east side of the South Patagonian Icefield. We focus on three different areas, where prior studies show ample glacier moraine records exist because they were formed by outlet glaciers sensitive to climate change. The 10Be dated records are from the Lago Pearson, Herminita Península-Brazo Upsala, and Lago Frías areas, which span a distance of almost 100 km adjacent to the modern Icefield. New 10Be ages show that expanded glaciers and moraine building events occurred at least at 6120 ± 390 (n = 13), 4450 ± 220 (n = 7), 1450 or 1410 ± 110 (n = 18), 360 ± 30 (n = 5), and 240 ± 20 (n = 8) years ago. Furthermore, other less well-dated glacier expansions of the Upsala Glacier occurred between 1400 and ∼1000 and ∼2300 and ∼2000 years ago. The most extensive glaciers occurred over the interval from ∼6100 to ∼4500 years ago, and their margins over the last ∼600 years were well within and lower than those in the middle Holocene. The 10Be ages agree with 14C-limiting data for the glacier histories in this area. We then link southern South American, adjacent South Atlantic, and other Southern Hemisphere records to elucidate broader regional patterns of climate and their possible causes. In the early Holocene, a far southward position of the westerly winds fostered warmth, small Patagonian glaciers, and reduced sea ice coverage over the South Atlantic. Although we infer a pronounced southward displacement of the westerlies during the early Holocene, these conditions did not occur throughout the southern mid-high latitudes, an important exception being over the southwest Pacific sector. Subsequently, a northward locus and/or expansion of the winds over the Patagonia-South Atlantic sector promoted the largest glaciers between ∼6100 and ∼4500 years ago and greatest sea ice coverage. Over the last few millennia, the South Patagonian Icefield has experienced

Evaluation of the Atlantic Multidecadal Oscillation Impact on Large-Scale Atmospheric Circulation in the Atlantic Region in Summer

Science.gov (United States)

Semenov, V. A.; Cherenkova, E. A.

2018-02-01

The influence of the Atlantic Multidecadal Oscillation (AMO) on large-scale atmospheric circulation in the Atlantic region in summer for the period of 1950-2015 is investigated. It is shown that the intensification of the summer North Atlantic Oscillation (NAO) with significant changes in sea level pressure anomalies in the main centers of action (over Greenland and the British Isles) occurred while the North Atlantic was cooler. Sea surface temperature anomalies, which are linked to the AMO in the summer season, affect both the NAO index and fluctuations of the Eastern Atlantic/Western Russia (EAWR) centers of action. The positive (negative) phase of the AMO is characterized by a combination of negative (positive) values of the NAO and EAWR indices. The dominance of the opposite phases of the teleconnection indices in summer during the warm North Atlantic and in its colder period resulted in differences in the regional climate in Europe.

Contrasting recruitment seasonality of sea urchin species in Gran Canaria, Canary Islands (eastern Atlantic

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S. GARCIA-SANZ

2014-03-01

Full Text Available Despite sea-urchins can play an important role affecting the community structure of subtidal bottoms, factors controlling the dynamics of sea-urchin populations are still poorly understood. We assessed the seasonal variation in recruitment of three sea-urchin species (Diadema africanum, Paracentrotus lividus and Arbacia lixula at Gran Canaria Island (eastern Atlantic via monthly deployment of artificial collectors throughout an entire annual cycle on each of four adjacent habitat patches (seagrasses, sandy patches, ‘urchin-grazed’ barrens and macroalgal-dominated beds within a shallow coastal landscape. Paracentrotus lividus and A. lixula had exclusively one main recruitment peak in late winter-spring. Diadema africanum recruitment was also seasonal, but recruits appeared in late summer-autumn, particularly on ‘urchin-grazed’ barrens with large abundances of adult conspecifics. In conclusion, this study has demonstrated non-overlapping seasonal recruitment patterns of the less abundant species (P. lividus and A. lixula with the most conspicuous species (D. africanum in the study area.

The role of Atlantic-Arctic exchange in North Atlantic multidecadal climate variability

NARCIS (Netherlands)

Frankcombe, L.M.; Dijkstra, H.A.

2011-01-01

It has recently been suggested that multidecadal variability in North Atlantic sea surface temperature occurs with two dominant periods. In this paper we investigate the origin of these two time scales in a 500 year control run of the GFDL CM2.1 model. We focus on the exchange between the Atlantic

Sea Ice and Hydrographic Variability in the Northwest North Atlantic

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Fenty, I. G.; Heimbach, P.; Wunsch, C. I.

2010-12-01

Sea ice anomalies in the Northwest North Atlantic's Labrador Sea are of climatic interest because of known and hypothesized feedbacks with hydrographic anomalies, deep convection/mode water formation, and Northern Hemisphere atmospheric patterns. As greenhouse gas concentrations increase, hydrographic anomalies formed in the Arctic Ocean associated with warming will propagate into the Labrador Sea via the Fram Strait/West Greenland Current and the Canadian Archipelago/Baffin Island Current. Therefore, understanding the dynamical response of sea ice in the basin to hydrographic anomalies is essential for the prediction and interpretation of future high-latitude climate change. Historically, efforts to quantify the link between the observed sea ice and hydrographic variability in the region has been limited due to in situ observation paucity and technical challenges associated with synthesizing ocean and sea ice observations with numerical models. To elaborate the relationship between sea ice and ocean variability, we create three one-year (1992-1993, 1996-1997, 2003-2004) three-dimensional time-varying reconstructions of the ocean and sea ice state in Labrador Sea and Baffin Bay. The reconstructions are syntheses of a regional coupled 32 km ocean-sea ice model with a suite of contemporary in situ and satellite hydrographic and ice data using the adjoint method. The model and data are made consistent, in a least-squares sense, by iteratively adjusting several model control variables (e.g., ocean initial and lateral boundary conditions and the atmospheric state) to minimize an uncertainty-weighted model-data misfit cost function. The reconstructions reveal that the ice pack attains a state of quasi-equilibrium in mid-March (the annual sea ice maximum) in which the total ice-covered area reaches a steady state -ice production and dynamical divergence along the coasts balances dynamical convergence and melt along the pack’s seaward edge. Sea ice advected to the

Lessons derived from two high-frequency sea level events in the Atlantic: implications for coastal risk analysis and tsunami detection

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Begoña Pérez-Gómez

2016-11-01

Full Text Available The upgrade and enhancement of sea level networks worldwide for integration in sea level hazard warning systems have significantly increased the possibilities for measuring and analyzing high frequency sea level oscillations, with typical periods ranging from a few minutes to a few hours. Many tide gauges now afford 1 min or more frequent sampling and have shown such events to be a common occurrence. Their origins and spatial distribution are diverse and must be well understood in order to correctly design and interpret, for example, the automatic detection algorithms used by tsunami warning centers. Two events recorded recently in European Atlantic waters are analyzed here: possible wave-induced seiches that occurred along the North coast of Spain during the storms of January and February of 2014, and oscillations detected after an earthquake in the mid-Atlantic the 13th of February of 2015. The former caused significant flooding in towns and villages and a huge increase in wave-induced coastal damage that was reported in the media for weeks. The second was a smaller signal present in several tide gauges along the Atlantic coast that, that coincided with the occurrence of this earthquake, leading to a debate on the potential detection of a very small tsunami and how it might yield significant information for tsunami wave modelers and for the development of tsunami detection software. These kinds of events inform us about the limitations of automatic algorithms for tsunami warning and help to improve the information provided to tsunami warning centers, whilst also emphasizing the importance of other forcings in generating extreme sea levels and their associated potential for causing damage to infrastructure.

Structural geology of the North and Middle Caspian sea on the new geophysical data interpretation

International Nuclear Information System (INIS)

Boris, V.S; Rais, V.Sh; Victor, L.U

2002-01-01

Full text:A structural and tectonic map of the North and Middle Caspian Sea is made on the basis of seismic and other geological and geophysical data analysis. According to the plotting results the total amplitude range of the heterogeneous basement depths are in the North Caspian Sea (Ukatnensky depression-over 12 km and Prorva depression-over 16 km). In the middle Caspian Sea the deppest basement point is supposed in Sulak basin (over 12 km). The least basement depths are marked in Karpinsky ridge,Buzachinky and Karabogazsky arches (1-3 km). On the whole the morphology and structure of the basement confirms the conclusion previously made by many researches that the Caspian Sea is a heterogeneous depression superimposed on the junction of regional tectonic elements of various ages.The ancient East-European platform represented by Pricaspiisky depression (Donetsko-Astrakhanskaya fault system limits the latter in the south) is situated on the North. The middle Caspian Sea is occupied with the offshore continuation of Terek-Caspian foredeep is represented by Sulak basin clearly limited in the south by a system of upthrusts and thrusts falling under North Caucasus foreland.Geological interpretation of the Yuzhmorgeologiya Center new geophysical data allows making an assumption about the biohermexistence within TriassicSea sediments on Kuma-Manychsky depression offshore continuation. Seismic exploration works show strike-slip faults and thrust structure development within the sedimentary cover on the offshore continuation of Karpinsky ridge.Some strike-slipped blocks are separated by left-side shifts of the northeast stretch.The pool location at the left-side (east) blocks of the shift areas is marked.

Other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from unknown platforms in the North Atlantic Ocean, North Sea and Norwegian Sea from 1874-01-01 to 2005-12-31 (NCEI Accession 0144342)

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National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0144342 includes discrete sample and profile data collected from unknown platforms in the North Atlantic Ocean, North Sea and Norwegian Sea from...

Characterization of natural variation in North American Atlantic Salmon populations (Salmonidae: Salmo salar) at a locus with a major effect on sea age.

Science.gov (United States)

Kusche, Henrik; Côté, Guillaume; Hernandez, Cécilia; Normandeau, Eric; Boivin-Delisle, Damien; Bernatchez, Louis

2017-08-01

Age at maturity is a key life-history trait of most organisms. In anadromous salmonid fishes such as Atlantic Salmon ( Salmo salar ), age at sexual maturity is associated with sea age, the number of years spent at sea before the spawning migration. For the first time, we investigated the presence of two nonsynonymous vgll3 polymorphisms in North American Atlantic Salmon populations that relate to sea age in European salmon and quantified the natural variation at these and two additional candidate SNPs from two other genes. A targeted resequencing assay was developed and 1,505 returning adult individuals of size-inferred sea age and sex from four populations were genotyped. Across three of four populations sampled in Québec, Canada, the late-maturing component (MSW) of the population of a given sex exhibited higher proportions of SNP genotypes 54Thr vgll3 and 323Lys vgll3 compared to early-maturing fish (1SW), for example, 85% versus 53% of females from Trinité River carried 323Lys vgll3 ( n MSW  = 205 vs. n 1SW  = 30; p 66%) to be female. In summary, two nonsynonymous vgll3 polymorphisms were confirmed in North American populations of Atlantic Salmon and our results suggest that variation at those loci correlates with sea age and sex. Our results also suggest that this correlation varies among populations. Future work would benefit from a more balanced sampling and from adding data on juvenile riverine life stages to contrast our data.

GHRSST Level 2P Atlantic Regional Bulk Sea Surface Temperature from the Advanced Very High Resolution Radiometer (AVHRR) on the NOAA-16 satellite (GDS version 1)

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National Oceanic and Atmospheric Administration, Department of Commerce — A regional Level 2P Group for High Resolution Sea Surface Temperature (GHRSST) dataset for the Atlantic Ocean and nearby regions based on multi-channel sea surface...

GHRSST Level 2P Atlantic Regional Bulk Sea Surface Temperature from the Advanced Very High Resolution Radiometer (AVHRR) on the NOAA-17 satellite (GDS version 1)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A regional Level 2P Group for High Resolution Sea Surface Temperature (GHRSST) dataset for the Atlantic Ocean and nearby regions based on multi-channel sea surface...

Somatic growth dynamics of West Atlantic hawksbill sea turtles: a spatio-temporal perspective

Science.gov (United States)

Bjorndal, Karen A.; Chaloupka, Milani; Saba, Vincent S.; Diez, Carlos E.; van Dam, Robert P.; Krueger, Barry H.; Horrocks, Julia A.; Santos, Armando J.B.; Bellini, Cláudio; Marcovaldi, Maria A.G.; Nava, Mabel; Willis, Sue; Godley, Brendan J.; Gore, Shannon; Hawkes, Lucy A.; McGowan, Andrew; Witt, Matthew J.; Stringell, Thomas B.; Sanghera, Amdeep; Richardson, Peter B.; Broderick, Annette C.; Phillips, Quinton; Calosso, Marta C.; Claydon, John A.B.; Blumenthal, Janice; Moncada, Felix; Nodarse, Gonzalo; Medina, Yosvani; Dunbar, Stephen G.; Wood, Lawrence D.; Lagueux, Cynthia J.; Campbell, Cathi L.; Meylan, Anne B.; Meylan, Peter A.; Burns Perez, Virginia R.; Coleman, Robin A.; Strindberg, Samantha; Guzmán-H, Vicente; Hart, Kristen M.; Cherkiss, Michael S.; Hillis-Starr, Zandy; Lundgren, Ian; Boulon, Ralf H.; Connett, Stephen; Outerbridge, Mark E.; Bolten, Alan B.

2016-01-01

Somatic growth dynamics are an integrated response to environmental conditions. Hawksbill sea turtles (Eretmochelys imbricata) are long-lived, major consumers in coral reef habitats that move over broad geographic areas (hundreds to thousands of kilometers). We evaluated spatio-temporal effects on hawksbill growth dynamics over a 33-yr period and 24 study sites throughout the West Atlantic and explored relationships between growth dynamics and climate indices. We compiled the largest ever data set on somatic growth rates for hawksbills – 3541 growth increments from 1980 to 2013. Using generalized additive mixed model analyses, we evaluated 10 covariates, including spatial and temporal variation, that could affect growth rates. Growth rates throughout the region responded similarly over space and time. The lack of a spatial effect or spatio-temporal interaction and the very strong temporal effect reveal that growth rates in West Atlantic hawksbills are likely driven by region-wide forces. Between 1997 and 2013, mean growth rates declined significantly and steadily by 18%. Regional climate indices have significant relationships with annual growth rates with 0- or 1-yr lags: positive with the Multivariate El Niño Southern Oscillation Index (correlation = 0.99) and negative with Caribbean sea surface temperature (correlation = −0.85). Declines in growth rates between 1997 and 2013 throughout the West Atlantic most likely resulted from warming waters through indirect negative effects on foraging resources of hawksbills. These climatic influences are complex. With increasing temperatures, trajectories of decline of coral cover and availability in reef habitats of major prey species of hawksbills are not parallel. Knowledge of how choice of foraging habitats, prey selection, and prey abundance are affected by warming water temperatures is needed to understand how climate change will affect productivity of consumers that live in association with coral reefs. Main

Variations of Sea Surface Temperature, Wind Stress, and Rainfall over the Tropical Atlantic and South America.

Science.gov (United States)

Nobre, Paulo; Srukla, J.

1996-10-01

Empirical orthogonal functions (E0Fs) and composite analyses are used to investigate the development of sea surface temperature (SST) anomaly patterns over the tropical Atlantic. The evolution of large-scale rainfall anomaly patterns over the equatorial Atlantic and South America are also investigated. 71e EOF analyses revealed that a pattern of anomalous SST and wind stress asymmetric relative to the equator is the dominant mode of interannual and longer variability over the tropical Atlantic. The most important findings of this study are as follows.Atmospheric circulation anomalies precede the development of basinwide anomalous SST patterns over the tropical Atlantic. Anomalous SST originate off the African coast simultaneously with atmospheric circulation anomalies and expand westward afterward. The time lag between wind stress relaxation (strengthening) and maximum SST warming (cooling) is about two months.Anomalous atmospheric circulation patterns over northern tropical Atlantic are phase locked to the seasonal cycle. Composite fields of SLP and wind stress over northern tropical Atlantic can be distinguished from random only within a few months preceding the March-May (MAM) season. Observational evidence is presented to show that the El Niño-Southern Oscillation phenomenon in the Pacific influences atmospheric circulation and SST anomalies over northern tropical Atlantic through atmospheric teleconnection patterns into higher latitudes of the Northern Hemisphere.The well-known droughts over northeastern Brazil (Nordeste) are a local manifestation of a much larger-scale rainfall anomaly pattern encompassing the whole equatorial Atlantic and Amazon region. Negative rainfall anomalies to the south of the equator during MAM, which is the rainy season for the Nordeste region, are related to an early withdrawal of the intertropical convergence zone toward the warm SST anomalies over the northern tropical Atlantic. Also, it is shown that precipitation anomalies

Influences of sediment redistribution on sea-level changes along the U.S. Atlantic margin since the mid-Pliocene

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Li, Q.; Ferrier, K.; Austermann, J.; Mitrovica, J. X.

2017-12-01

The Orangeburg Scarp is a paleo-shoreline formed along the southeastern U.S. Atlantic coast during the mid-Pliocene warm period (MPWP; 3.3 - 2.9 Ma). The MPWP is a time of interest because it is often cited as an analog for modern climate and thus an important target for understanding sea-level responses to climate change. The present Orangeburg Scarp exhibits 40-meter variations in elevation along its length, implying that it has been warped since its formation, which complicates efforts to infer global ice volume at the MPWP. Previous studies have shown that the effects of glacial isostatic adjustment (GIA) and dynamic topography (DT) on sea level can explain a significant fraction of the observed variability in elevation along the Orangeburg Scarp. Here we build on these studies by using a gravitationally self-consistent ice age sea-level model to compute the effects of sediment loading and unloading on paleo-shoreline elevation since the mid-Pliocene. To constrain the sediment loading history in this region, we present a new compilation of erosion and deposition rates along the U.S. Atlantic margin, from which we generate a range of sediment redistribution scenarios since the MPWP. We simultaneously drive the sea-level model with these sediment redistribution histories and existing ice and dynamic topography histories. Our results show that sediment loading and unloading is capable of warping the elevation of this paleo-shoreline by 20 meters since its formation, similar in magnitude to the contributions from GIA and DT over the same time period. These results demonstrate that sediment redistribution can induce significant perturbations in sea-level markers from the MPWP, and thus accounting for its influence will improve reconstructions of sea level and global ice volume during the MPWP and perhaps other periods of relative ice age warmth.

Sequence stratigraphy and a revised sea-level curve for the Middle Devonian of eastern North America

Science.gov (United States)

Brett, Carlton E.; Baird, G.C.; Bartholomew, A.J.; DeSantis, M.K.; Ver Straeten, C.A.

2011-01-01

The well-exposed Middle Devonian rocks of the Appalachian foreland basin (Onondaga Formation; Hamilton Group, Tully Formation, and the Genesee Group of New York State) preserve one of the most detailed records of high-order sea-level oscillation cycles for this time period in the world. Detailed examination of coeval units in distal areas of the Appalachian Basin, as well as portions of the Michigan and Illinois basins, has revealed that the pattern of high-order sea-level oscillations documented in the New York-Pennsylvania section can be positively identified in all areas of eastern North America where coeval units are preserved. The persistence of the pattern of high-order sea-level cycles across such a wide geographic area suggests that these cycles are allocyclic in nature with primary control on deposition being eustatic sea-level oscillation, as opposed to autocylic controls, such as sediment supply, which would be more local in their manifestation. There is strong evidence from studies of cyclicity and spectral analysis that these cycles are also related to Milankovitch orbital variations, with the short and long-term eccentricity cycles (100. kyr and 405. kyr) being the dominant oscillations in many settings. Relative sea-level oscillations of tens of meters are likely and raise considerable issues about the driving mechanism, given that the Middle Devonian appears to record a greenhouse phase of Phanerozoic history. These new correlations lend strong support to a revised high-resolution sea-level oscillation curve for the Middle Devonian for the eastern portion of North America. Recognized third-order sequences are: Eif-1 lower Onondaga Formation, Eif-2: upper Onondaga and Union Springs formations; Eif-Giv: Oatka Creek Formation; Giv-1: Skaneateles, Giv-2: Ludlowville, Giv-3: lower Moscow, Giv-4: upper Moscow-lower Tully, and Giv-5: middle Tully-Geneseo formations. Thus, in contrast with the widely cited eustatic curve of Johnson et al. (1985), which

Underway sea surface temperature and salinity data from thermosalinographs collected from multiple platforms assembled by NOAA Atlantic Oceanographic and Meteorological Laboratory (AOML)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This collection contains sea surface oceanographic data in netCDF and ASCII formatted files assembled by the NOAA Atlantic Oceanographic and Meteorological...

Formation of Barents Sea Branch Water in the north-eastern Barents Sea

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Vidar S. Lien

2013-09-01

Full Text Available The Barents Sea throughflow accounts for approximately half of the Atlantic Water advection to the Arctic Ocean, while the other half flows through Fram Strait. Within the Barents Sea, the Atlantic Water undergoes considerable modifications before entering the Arctic Ocean through the St. Anna Trough. While the inflow area in the south-western Barents Sea is regularly monitored, oceanographic data from the outflow area to the north-east are very scarce. Here, we use conductivity, temperature and depth data from August/September 2008 to describe in detail the water masses present in the downstream area of the Barents Sea, their spatial distribution and transformations. Both Cold Deep Water, formed locally through winter convection and ice-freezing processes, and Atlantic Water, modified mainly through atmospheric cooling, contribute directly to the Barents Sea Branch Water. As a consequence, it consists of a dense core characterized by a temperature and salinity maximum associated with the Atlantic Water, in addition to the colder, less saline and less dense core commonly referred to as the Barents Sea Branch Water core. The denser core likely constitutes a substantial part of the total flow, and it is more saline and considerably denser than the Fram Strait branch as observed within the St. Anna Trough. Despite the recent warming of the Barents Sea, the Barents Sea Branch Water is denser than observed in the 1990s, and the bottom water observed in the St. Anna Trough matches the potential density at 2000 m depth in the Arctic Ocean.

Isotope paleoclimatology and Atlantic deep water history since 15 million years

International Nuclear Information System (INIS)

Blanc, P.L.

1981-12-01

18 O/ 16 O and 13 C/ 12 C ratios measurements in foraminiferal calcite are applied to the paleoclimatology of the North Atlantic and to the reconstruction of deep water exchanges between the Atlantic and Pacific Oceans, from middle miocene time (15 m.y. ago) to the present, on samples from 2 DSDP wells. Chapters 1 to 4 describe the structural frame and hydrological setting of these sites, and the stratigraphy of the deposits. A .4 m.y. lag between the initiation of the first boreal ice-caps and their extension to northern Europe is explained by the persistency of the North-Atlantic Drift. In chapters 5 to 8, the 13 C/ 12 C ratio of dissolved mineral carbon is used as a tracer of the residence time of the deep waters, the indications of which are preserved in benthonic foraminiferal calcite. It is shown that present-day type thermo-haline circulation was initiated 13.2 m.y. ago in the northern Atlantic, when the volcanic Scotland-Iceland-Greenland ridge subsided; that the closure of the Mediterranean sea during the Messinian (6.2 to 5 m.y. ago) caused this circulation to stop, and that the present circulation started again when the Mediterranean re-opened, at the beginning of the Pliocene [fr

Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years.

Science.gov (United States)

Thornalley, David J R; Oppo, Delia W; Ortega, Pablo; Robson, Jon I; Brierley, Chris M; Davis, Renee; Hall, Ian R; Moffa-Sanchez, Paola; Rose, Neil L; Spooner, Peter T; Yashayaev, Igor; Keigwin, Lloyd D

2018-04-01

The Atlantic meridional overturning circulation (AMOC) is a system of ocean currents that has an essential role in Earth's climate, redistributing heat and influencing the carbon cycle 1, 2 . The AMOC has been shown to be weakening in recent years 1 ; this decline may reflect decadal-scale variability in convection in the Labrador Sea, but short observational datasets preclude a longer-term perspective on the modern state and variability of Labrador Sea convection and the AMOC 1, 3-5 . Here we provide several lines of palaeo-oceanographic evidence that Labrador Sea deep convection and the AMOC have been anomalously weak over the past 150 years or so (since the end of the Little Ice Age, LIA, approximately AD 1850) compared with the preceding 1,500 years. Our palaeoclimate reconstructions indicate that the transition occurred either as a predominantly abrupt shift towards the end of the LIA, or as a more gradual, continued decline over the past 150 years; this ambiguity probably arises from non-AMOC influences on the various proxies or from the different sensitivities of these proxies to individual components of the AMOC. We suggest that enhanced freshwater fluxes from the Arctic and Nordic seas towards the end of the LIA-sourced from melting glaciers and thickened sea ice that developed earlier in the LIA-weakened Labrador Sea convection and the AMOC. The lack of a subsequent recovery may have resulted from hysteresis or from twentieth-century melting of the Greenland Ice Sheet 6 . Our results suggest that recent decadal variability in Labrador Sea convection and the AMOC has occurred during an atypical, weak background state. Future work should aim to constrain the roles of internal climate variability and early anthropogenic forcing in the AMOC weakening described here.

Marine environmental monitoring related to sea disposal of radioactive waste in the NE Atlantic Ocean

International Nuclear Information System (INIS)

Bettencourt, A.O.; Elias, M.D.T.; Ferrador, G.C.

1988-01-01

Reference is made to the sea disposal of packaged radioactive waste in the NE Atlantic and to the role of the OCDE Nuclear Energy Agency (NEA) since 1967, in the dumping operations. The objectives of marine environmental monitoring in relation to sea disposal of radioactive wastes are described as well as the coordinated research and environmental surveillance programme (CRESP) developed within NEA frame. The Portuguese on-going programme in this field is presented and the results concerning measurements of 239+240 Pu, 238 Pu, 241 Am and 137 Cs in samples of water, sediments and fish collected at Madeira and Continental Portuguese coasts, are discussed. It was observed that these radionuclides concentrations are lower for deep-sea fishes than for the shallow-water ones. The obtained results are compared with those found in the literature. From the observation of the large spectrum of results available, it can be concluded that no generalized contamination of the marine environment due to the sea dumping of radioactive wastes if observed at present. On the other hand, there is an interest in pursuing analyses of deep-sea fish with the aim of early detection of any possible modifications in the actual levels of radioactivity in the marine environment. (author) [pt

Aerosol Radiative Impact on the Middle East Regional Climate and the Red Sea

KAUST Repository

Osipov, Sergey

2017-10-01

The climate in the Middle East is complex and remains poorly understood. Due to the vast Arabian Desert, it is very sensitive to radiative forcing. Mineral dust is the dominant aerosol in this region. High background dust loading and frequent dust outbreaks significantly perturb the radiative balance and contribute to climate variability in the Middle East. To assess the climatological impact of dust in the region, we derived the aerosol optical properties and used a standalone column model to quantify radiative forcing sensitivity to a range of parameters representative of the Arabian Peninsula and the Red Sea. Simulations and modeling assumptions were validated using available in situ observations and satellite retrievals for fair weather and dust storm conditions. We incorporated the optical properties into the regional coupled ocean-atmosphere model and conducted simulations that represent the regional climate. The analysis shows that dust cools the Earth-atmosphere system and thus offsets the warming due to greenhouse gases. Dust reduces the sea surface temperature by 0.4 K, significantly perturbs energy balance, overturning circulation, and its purely dynamical impact reduces biological productivity in the Red Sea. In the real world, dust is present permanently and this does not allow to directly observe the climate response to the dust forcing. Volcanic eruptions produce a transient radiative impact that causes a detectable climate response that could be evaluated from observations and compared with simulations. Large equatorial eruptions are known to significantly perturb the Earth’s climate on the global scale, but their regional impact on the Middle East has not been thoroughly investigated. For example, the 1991 Mount Pinatubo eruption had a profound effect on the MENA and caused extensive coral bleaching in the Gulf of Aqaba. The analysis shows that observed cooling in the Middle East was mostly driven by changes in the atmospheric large

Decadal variability of extreme wave height representing storm severity in the northeast Atlantic and North Sea since the foundation of the Royal Society

Science.gov (United States)

Santo, H.; Taylor, P. H.; Gibson, R.

2016-09-01

Long-term estimation of extreme wave height remains a key challenge because of the short duration of available wave data, and also because of the possible impact of climate variability on ocean waves. Here, we analyse storm-based statistics to obtain estimates of extreme wave height at locations in the northeast Atlantic and North Sea using the NORA10 wave hindcast (1958-2011), and use a 5 year sliding window to examine temporal variability. The decadal variability is correlated to the North Atlantic oscillation and other atmospheric modes, using a six-term predictor model incorporating the climate indices and their Hilbert transforms. This allows reconstruction of the historic extreme climate back to 1661, using a combination of known and proxy climate indices. Significant decadal variability primarily driven by the North Atlantic oscillation is observed, and this should be considered for the long-term survivability of offshore structures and marine renewable energy devices. The analysis on wave climate reconstruction reveals that the variation of the mean, 99th percentile and extreme wave climates over decadal time scales for locations close to the dominant storm tracks in the open North Atlantic are comparable, whereas the wave climates for the rest of the locations including the North Sea are rather different.

2 - 4 million years of sedimentary processes in the Labrador Sea: implication for North Atlantic stratigraphy

Science.gov (United States)

Mosher, D. C.; Saint-Ange, F.; Campbell, C.; Piper, D. J.

2012-12-01

Marine sedimentary records from the western North Atlantic show that a significant portion of sediment deposited since the Pliocene originated from the Canadian Shield. In the Labrador Sea, previous studies have shown that bottom currents .strongly influenced sedimentation during the Pliocene, while during the Quaternary, intensification of turbidity current flows related to meltwater events were a dominant factor in supplying sediment to the basin and in the development of the North Atlantic Mid-Ocean Channel (NAMOC). Despite understanding this general pattern of sediment flux, details regarding the transfer of sediment from the Labrador Shelf to deep water and from the Labrador Sea to the North Atlantic remain poorly understood. Our study focuses on sedimentary processes occurring along the Labrador margin since the Pliocene and their consequences on the margin architecture, connection to the NAMOC, and role in sediment flux from the Labrador basin to the Sohm Abyssal Plain. Piston core and high resolution seismic data reveal that during the Pliocene to mid Pleistocene, widespread slope failures led to mass transport deposition along the entire Labrador continental slope. After the mid Pleistocene, sedimentation along the margin was dominated by the combined effects of glaciation and active bottom currents. On the shelf, prograded sedimentary wedges filled troughs and agraded till sheets form intervening banks. On the slope, stacked glaciogenic fans developed seaward of transverse troughs between 400 and 2800 mbsl. On the lower slope, seismic data show thick sediment drifts capped by glacio-marine mud. This unit is draped by well stratified sediment and marks a switch from a contourite dominated regime to a turbidite dominated regime. This shift occurred around 0.5 - 0.8 ka and correlates to the intensification of glaciations. Late Pleistocene sediments on the upper slope consist of stratified sediments related to proglacial plume fall-out. Coarse grained

Mechanisms of decadal variability in the Labrador Sea and the wider North Atlantic in a high-resolution climate model

Science.gov (United States)

Ortega, Pablo; Robson, Jon; Sutton, Rowan T.; Andrews, Martin B.

2017-10-01

A necessary step before assessing the performance of decadal predictions is the evaluation of the processes that bring memory to the climate system, both in climate models and observations. These mechanisms are particularly relevant in the North Atlantic, where the ocean circulation, related to both the Subpolar Gyre and the Meridional Overturning Circulation (AMOC), is thought to be important for driving significant heat content anomalies. Recently, a rapid decline in observed densities in the deep Labrador Sea has pointed to an ongoing slowdown of the AMOC strength taking place since the mid 90s, a decline also hinted by in-situ observations from the RAPID array. This study explores the use of Labrador Sea densities as a precursor of the ocean circulation changes, by analysing a 300-year long simulation with the state-of-the-art coupled model HadGEM3-GC2. The major drivers of Labrador Sea density variability are investigated, and are characterised by three major contributions. First, the integrated effect of local surface heat fluxes, mainly driven by year-to-year changes in the North Atlantic Oscillation, which accounts for 62% of the total variance. Additionally, two multidecadal-to-centennial contributions from the Greenland-Scotland Ridge outflows are quantified; the first associated with freshwater exports via the East Greenland Current, and the second with density changes in the Denmark Strait Overflow. Finally, evidence is shown that decadal trends in Labrador Sea densities are followed by important atmospheric impacts. In particular, a positive winter NAO response appears to follow the negative Labrador Sea density trends, and provides a phase reversal mechanism.

Population structure of Atlantic Mackerel (Scomber scombrus)

DEFF Research Database (Denmark)

Jansen, Teunis; Gislason, Henrik

2013-01-01

Atlantic mackerel (Scomber scombrus) occurs on both sides of the north Atlantic and has traditionally been grouped into 5 spawning components, some of which were thought to be isolated natal homing stocks. Previous studies have provided no evidence for cross Atlantic migration and no or weak...... between the North Sea and Celtic Sea, which indicates that the two spawning components may be connected by straying individuals. This finding is based on unique larvae samples collected before the collapse of North Sea component, thus showing that the exchange is not a recent phenomenon due...... to the collapse. The analyses of old as well as more recent age distributions show that strong year classes spread into other areas where they spawn as adults (“twinning”). Our findings are in accordance with the lack of solid evidence for stock separation from previous analyses of tagging data, genetics...

Oceanographic Telecommuting: Going to Sea Virtually

Science.gov (United States)

Smith, Deborah K.; Lemmond, Peter

2005-09-01

Oceanography in the 21st century is on the verge of changing the way it does business. Telecommuting from office to sea is about to make the same impact as telecommuting between home and the office did 20 years ago. A recent geophysical survey highlighted the role that telecommuting will soon play in ocean research. In June 2005, R/V Knorr was in the middle of the Atlantic Ocean conducting a geophysical survey of a region centered at 13°N along the Mid-Atlantic Ridge in the general area of the diffuse triple junction between the North America (NA),Africa (AF), and South America (SA) plates. This region is particularly notable because of a unique zone of seismicity that occurs ~70 km west of the ridge axis between 14°20'N and 12°50'N.The survey conducted on this cruise (KN182-3) was a first step toward understanding how slow spreading lithosphere is deforming in the NA-SA-AF triple junction region.

Simulated variability of the Atlantic meridional overturning circulation

Science.gov (United States)

Bentsen, M.; Drange, H.; Furevik, T.; Zhou, T.

To examine the multi-annual to decadal scale variability of the Atlantic Meridional Overturning Circulation (AMOC) we conducted a four-member ensemble with a daily reanalysis forced, medium-resolution global version of the isopycnic coordinate ocean model MICOM, and a 300-years integration with the fully coupled Bergen Climate Model (BCM). The simulations of the AMOC with both model systems yield a long-term mean value of 18 Sv and decadal variability with an amplitude of 1-3 Sv. The power spectrum of the inter-annual to decadal scale variability of the AMOC in BCM generally follows the theoretical red noise spectrum, with indications of increased power near the 20-years period. Comparison with observational proxy indices for the AMOC, e.g. the thickness of the Labrador Sea Water, the strength of the baroclinic gyre circulation in the North Atlantic Ocean, and the surface temperature anomalies along the mean path of the Gulf Stream, shows similar trends and phasing of the variability, indicating that the simulated AMOC variability is robust and real. Mixing indices have been constructed for the Labrador, the Irminger and the Greenland-Iceland-Norwegian (GIN) seas. While convective mixing in the Labrador and the GIN seas are in opposite phase, and linked to the NAO as observations suggest, the convective mixing in the Irminger Sea is in phase with or leads the Labrador Sea. Newly formed deep water is seen as a slow, anomalous cold and fresh, plume flowing southward along the western continental slope of the Atlantic Ocean, with a return flow of warm and saline water on the surface. In addition, fast-travelling topographically trapped waves propagate southward along the continental slope towards equator, where they go east and continue along the eastern rim of the Atlantic. For both types of experiments, the Northern Hemisphere sea level pressure and 2 m temperature anomaly patterns computed based on the difference between climate states with strong and weak AMOC

Multigene phylogeny of the scyphozoan jellyfish family Pelagiidae reveals that the common U.S. Atlantic sea nettle comprises two distinct species (Chrysaora quinquecirrha and C. chesapeakei

Directory of Open Access Journals (Sweden)

Keith M. Bayha

2017-10-01

Full Text Available Background Species of the scyphozoan family Pelagiidae (e.g., Pelagia noctiluca, Chrysaora quinquecirrha are well-known for impacting fisheries, aquaculture, and tourism, especially for the painful sting they can inflict on swimmers. However, historical taxonomic uncertainty at the genus (e.g., new genus Mawia and species levels hinders progress in studying their biology and evolutionary adaptations that make them nuisance species, as well as ability to understand and/or mitigate their ecological and economic impacts. Methods We collected nuclear (28S rDNA and mitochondrial (cytochrome c oxidase I and 16S rDNA sequence data from individuals of all four pelagiid genera, including 11 of 13 currently recognized species of Chrysaora. To examine species boundaries in the U.S. Atlantic sea nettle Chrysaora quinquecirrha, specimens were included from its entire range along the U.S. Atlantic and Gulf of Mexico coasts, with representatives also examined morphologically (macromorphology and cnidome. Results Phylogenetic analyses show that the genus Chrysaora is paraphyletic with respect to other pelagiid genera. In combined analyses, Mawia, sampled from the coast of Senegal, is most closely related to Sanderia malayensis, and Pelagia forms a close relationship to a clade of Pacific Chrysaora species (Chrysaora achlyos, Chrysaora colorata, Chrysaora fuscescens, and Chrysaora melanaster. Chrysaora quinquecirrha is polyphyletic, with one clade from the U.S. coastal Atlantic and another in U.S. Atlantic estuaries and Gulf of Mexico. These genetic differences are reflected in morphology, e.g., tentacle and lappet number, oral arm length, and nematocyst dimensions. Caribbean sea nettles (Jamaica and Panama are genetically similar to the U.S. Atlantic estuaries and Gulf of Mexico clade of Chrysaora quinquecirrha. Discussion Our phylogenetic hypothesis for Pelagiidae contradicts current generic definitions, revealing major disagreements between DNA-based and

Genetic homogeneity in the deep-sea grenadier Macrourus berglax across the North Atlantic Ocean

Science.gov (United States)

Coscia, Ilaria; Castilho, Rita; Massa-Gallucci, Alexia; Sacchi, Carlotta; Cunha, Regina L.; Stefanni, Sergio; Helyar, Sarah J.; Knutsen, Halvor; Mariani, Stefano

2018-02-01

Paucity of data on population structure and connectivity in deep sea species remains a major obstacle to their sustainable management and conservation in the face of ever increasing fisheries pressure and other forms of impacts on deep sea ecosystems. The roughhead grenadier Macrourus berglax presents all the classical characteristics of a deep sea species, such as slow growth and low fecundity, which make them particularly vulnerable to anthropogenic impact, due to their low resilience to change. In this study, the population structure of the roughhead grenadier is investigated throughout its geographic distribution using two sets of molecular markers: a partial sequence of the Control Region of mitochondrial DNA and species-specific microsatellites. No evidence of significant structure was found throughout the North Atlantic, with both sets of molecular markers yielding the same results of overall homogeneity. We posit two non-mutually exclusive scenarios that can explain such outcome: i) substantial high gene flow among locations, possibly maintained by larval stages, ii) very large effective size of post-glacially expanded populations. The results can inform management strategies in this by-caught species, and contribute to the broader issue of biological connectivity in the deep ocean.

76 FR 13583 - Atlantic Highly Migratory Species; Atlantic Bluefin Tuna Quotas and Atlantic Tuna Fisheries...

Science.gov (United States)

2011-03-14

... address concerns raised in a recent decision by a NOAA Administrative Law Judge (see Atlantic Tunas Transfer at Sea section for case reference). NMFS has prepared a draft Environmental Assessment (EA... subtraction of these allocations directly from the TAC, the recommendation allocates the remainder to the UK...

Comparative visual ecophysiology of mid-Atlantic temperate reef fishes

Directory of Open Access Journals (Sweden)

Andrij Z. Horodysky

2013-11-01

The absolute light sensitivities, temporal properties, and spectral sensitivities of the visual systems of three mid-Atlantic temperate reef fishes (Atlantic spadefish [Ephippidae: Chaetodipterus faber], tautog [Labridae: Tautoga onitis], and black sea bass [Serranidae: Centropristis striata] were studied via electroretinography (ERG. Pelagic Atlantic spadefish exhibited higher temporal resolution but a narrower dynamic range than the two more demersal foragers. The higher luminous sensitivities of tautog and black sea bass were similar to other benthic and demersal coastal mid-Atlantic fishes. Flicker fusion frequency experiments revealed significant interspecific differences at maximum intensities that correlated with lifestyle and habitat. Spectral responses of the three species spanned 400–610 nm, with high likelihood of cone dichromacy providing the basis for color and contrast discrimination. Significant day-night differences in spectral responses were evident in spadefish and black sea bass but not tautog, a labrid with characteristic structure-associated nocturnal torpor. Atlantic spadefish responded to a wider range of wavelengths than did deeper-dwelling tautog or black sea bass. Collectively, these results suggest that temperate reef-associated fishes are well-adapted to their gradient of brighter to dimmer photoclimates, representative of their unique ecologies and life histories. Continuing anthropogenic degradation of water quality in coastal environments, at a pace faster than the evolution of visual systems, may however impede visual foraging and reproductive signaling in temperate reef fishes.

The North Atlantic Ocean Is in a State of Reduced Overturning

Science.gov (United States)

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

2018-02-01

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

Atlantic continental margin of the United States

Science.gov (United States)

Grow, John A.; Sheridan, Robert E.; Palmer, A.R.

1982-01-01

The objective of this Decade of North American Geology (D-NAG) volume will be to focus on the Mesozoic and Cenozoic evolution of the U.S. Atlantic continental margin, including the onshore coastal plain, related onshore Triassic-Jurassic rift grabens, and the offshore basins and platforms. Following multiple compressional tectonic episodes between Africa and North America during the Paleozoic Era that formed the Appalachian Mountains, the Mesozoic and Cenozoic Eras were dominated by tensional tectonic processes that separated Africa and North America. Extensional rifting during Triassic and Early Jurassic times resulted in numerous tensional grabens both onshore and offshore, which filled with nonmarine continental red beds, lacustrine deposits, and volcanic flows and debris. The final stage of this breakup between Africa and North America occurred beneath the present outer continental shelf and continental slope during Early or Middle Jurassic time when sea-floor spreading began to form new oceanic crust and lithosophere between the two continents as they drifted apart. Postrift subsidence of the marginal basins continued in response to cooling of the lithosphere and sedimentary loading.Geophysical surveys and oil-exploration drilling along the U.S. Atlantic continental margin during the past 5 years are beginning to answer many questions concerning its deep structure and stratigraphy and how it evolved during the rifting and early sea-floor-spreading stages of the separation of this region from Africa. Earlier geophysical studies of the U.S. continental margin used marine refraction and submarine gravity measurements. Single-channel seismic-reflection, marine magnetic, aeromagnetic, and continuous gravity measurements became available during the 1960s.

Air-Sea CO2 fluxes in the Atlantic as measured during boreal spring and autumn

Directory of Open Access Journals (Sweden)

A. F. Ríos

2010-05-01

Full Text Available A total of fourteen hydrographic cruises from 2000 to 2008 were conducted during the spring and autumn seasons between Spain and the Southern Ocean under the framework of the Spanish research project FICARAM. The underway measurements were processed and analysed to describe the meridional air-sea CO2 fluxes (FCO2 in the covered sector of the Atlantic Ocean. The data has been grouped into different biogeochemical oceanographic provinces based on thermohaline characteristics. The spatial and temporal distributions of FCO2 followed expected distributions and annual trends reproducing the recent climatological ΔfCO2 estimations with a mean difference of −3 ± 18 μatm (Takahashi et al., 2009. The reduction in the CO2 saturation along the meridional FICARAM cruises represented an increase of 0.02 ± 0.14 mol m−2 yr−1 in the ocean uptake of atmospheric CO2. The subtropical waters in both Hemispheres acted as a sink of atmospheric CO2 during the successive spring seasons and as a source in autumn. The coarse reduction of the ocean uptake of atmospheric CO2 observed in the North Atlantic Ocean was linked to conditions of negative phase of the North Atlantic Oscillation that prevailed during the FICARAM period. Surface waters in the North Equatorial Counter Current revealed a significant long-term decrease of sea surface salinity of −0.16 ± 0.01 yr−1 coinciding with a declination of −3.5 ± 0.9 μatm yr−1 in the air–sea disequilibrium of CO2 fugacity and a rise of oceanic CO2 uptake of −0.09 ± 0.03 mol m−2 yr−1. The largest CO2 source was located in the equatorial upwelling system. These tropical waters that reached emissions of 0.7 ± 0.5 and 1.0 ± 0.7 mol m−2 y−1 in spring and autumn, respectively, showed an interannual warming of 0.11 ± 0.03 °C yr−1 and a wind speed decrease of −0.58 ± 0.14 m s−1 yr−1 in spring cruises which suggest the weakening of upwelling events associated with warm El Niño – Southern

Surfactant control of air-sea gas exchange from North Sea coastal waters and the Atlantic Meridional Transect

Science.gov (United States)

Pereira, R.

2016-02-01

Suppression of gas transfer velocity (kw) by surfactants are well established, both in laboratory wind flumes and purposeful oceanic releases. However, the effects on kw of time and space varying concentrations of natural surfactant are inadequately studied. We have developed an automated gas exchange tank for simultaneous high precision measurement of kw in unmodified seawater samples. Here we present data from two studies along a coastal North Sea transect during 2012-2013 and the Atlantic Meridional Transect (AMT) 24 from September to November 2014. Measurements of surfactant activity (SA), CDOM absorbance and chlorophyll-a have enabled us to characterize the effects of variable amounts of natural surfactant on kw. North Sea coastal waters range in k660 (kw normalized to the value for CO2 in freshwater at 20oC) was 6.8-24.5 cm hr-1 (n=20), with the ranges of SA, total CDOM absorbance (200-450 nm) and chlorophyll-a measured in the surface microlayer (SML) of our seawater samples were 0.08-0.38 mg l-1 T-X-100, 0.13-4.7 and 0.09-1.54 µg l-1, respectively. The AMT k660 ranged from 7.0-23.9 cm hr-1 (n=22), with SA measured in the SML and subsurface water (SSW) of our seawater samples ranging from 0.15-1.08 mg l-1 T-X-100 and 0.07-0.43 mg l-1 T-X-100, respectively. Importantly, we found 12-45% (North Sea) and 1-43% (AMT) k660 suppression relative to Milli-Q water that relate to seasonal and spatial differences in SA. The North Sea demonstrated notable seasonal influences on k660 suppression that were related to CDOM absorbance and chlorophyll-a. The degree of k660 suppression was highest in summer consistent with k660 control by natural surfactant. The degree of k660 suppression decreased with distance offshore in the North Sea and displayed a strong relationship with SA (r2 = 0.51-0.64, p = 0.02, n = 20). The AMT demonstrated notable differences in k660 suppression between hemispheres and across the Longhurst Provinces but the overall relationship between k660

An Atlantic streamer in stratospheric ozone observations and SD-WACCM simulation data

Science.gov (United States)

Hocke, Klemens; Schranz, Franziska; Maillard Barras, Eliane; Moreira, Lorena; Kämpfer, Niklaus

2017-03-01

Observation and simulation of individual ozone streamers are important for the description and understanding of non-linear transport processes in the middle atmosphere. A sudden increase in mid-stratospheric ozone occurred above central Europe on 4 December 2015. The GROund-based Millimeter-wave Ozone Spectrometer (GROMOS) and the Stratospheric Ozone MOnitoring RAdiometer (SOMORA) in Switzerland measured an ozone enhancement of about 30 % at 34 km altitude (8.3 hPa) from 1 to 4 December. A similar ozone increase is simulated by the Specified Dynamics Whole Atmosphere Community Climate (SD-WACCM) model. Further, the global ozone fields at 34 km altitude (8.3 hPa) from SD-WACCM and the satellite experiment Aura/MLS show a remarkable agreement for the location and timing of an ozone streamer (large-scale tongue-like structure) extending from the subtropics in northern America over the Atlantic to central Europe. This agreement indicates that SD-WACCM can inform us about the wind inside the Atlantic ozone streamer. SD-WACCM shows an eastward wind of about 100 m s-1 inside the Atlantic streamer in the mid-stratosphere. SD-WACCM shows that the Atlantic streamer flows along the edge of the polar vortex. The Atlantic streamer turns southward at an erosion region of the polar vortex located above the Caspian Sea. The spatial distribution of stratospheric water vapour indicates a filament outgoing from this erosion region. The Atlantic streamer, the polar vortex erosion region and the water vapour filament belong to the process of planetary wave breaking in the so-called surf zone of the northern midlatitude winter stratosphere.

Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from KNORR in the North Atlantic Ocean, North Greenland Sea and others from 1972-07-18 to 1973-04-01 (NCEI Accession 0143398)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0143398 includes discrete sample and profile data collected from KNORR in the North Atlantic Ocean, North Greenland Sea, Norwegian Sea, South Atlantic...

Global latitudinal species diversity gradient in deep-sea benthic foraminifera

Science.gov (United States)

Culver, Stephen J.; Buzas, Martin A.

2000-02-01

Global scale patterns of species diversity for modern deep-sea benthic foraminifera, an important component of the bathyal and abyssal meiofauna, are examined using comparable data from five studies in the Atlantic, ranging over 138° of latitude from the Norwegian Sea to the Weddell Sea. We show that a pattern of decreasing diversity with increasing latitude characterises both the North and South Atlantic. This pattern is confirmed for the northern hemisphere by independent data from the west-central North Atlantic and the Arctic basin. Species diversity in the North Atlantic northwards from the equator is variable until a sharp fall in the Norwegian Sea (ca. 65°N). In the South Atlantic species diversity drops from a maximum in latitudes less than 30°S and then decreases slightly from 40 to 70°S. For any given latitude, North Atlantic diversity is generally lower than in the South Atlantic. Both ecological and historical factors related to food supply are invoked to explain the formation and maintenance of the latitudinal gradient of deep-sea benthic foraminiferal species diversity. The gradient formed some 36 million years ago when global climatic cooling led to seasonally fluctuating food supply in higher latitudes.

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

Science.gov (United States)

Münnich, M.; Neelin, J. D.

2005-11-01

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

A field efficacy evaluation of emamectin benzoate for the control of sea lice on Atlantic salmon.

OpenAIRE

Armstrong, R; MacPhee, D; Katz, T; Endris, R

2000-01-01

This study evaluated the efficacy of emamectin benzoate, 0.2% aquaculture premix, against sea lice on Atlantic salmon in eastern Canada. Salmon pens received either emamectin benzoate, orally, in feed at 50 micrograms/kg body weight/day for 7 consecutive days, or the same diet with no added medication. The site veterinarian had the option of administering a bath treatment with azamethiphos to any pen in the trial. The mean number of lice per fish was lower (P < 0.05) in the experimental group...

Younger Dryas sea level and meltwater pulse 1B recorded in Barbados reef crest coral Acropora palmata

Science.gov (United States)

Abdul, N. A.; Mortlock, R. A.; Wright, J. D.; Fairbanks, R. G.

2016-02-01

The Younger Dryas climate event occurred during the middle of the last deglacial cycle and is marked by an abrupt shift in the North Atlantic polar front almost to its former glacial position, trending east to west. Using high-precision and high-accuracy U-Th-dated Barbados reef crest coral, Acropora palmata, we generate a detailed sea level record from 13.9 to 9000 years before present (kyr B.P.) and reconstruct the ice volume response to the Younger Dryas cooling. From the mid-Allerød (13.9 kyr B.P.) to the end of the Younger Dryas (11.65 kyr B.P.), rates of sea level rise decreased smoothly from 20 mm yr-1 to 4 mm yr-1, culminating in a 400 year "slow stand" before accelerating into meltwater pulse 1B (MWP-1B). The MWP-1B event at Barbados is better constrained as beginning by 11.45 kyr B.P. and ending at 11.1 kyr B.P. during which time sea level rose 14 ± 2 m and rates of sea level rise reached 40 mm yr-1. We propose that MWP-1B is the direct albeit lagged response of the Northern Hemisphere ice sheets to the rapid warming marking the end of the Younger Dryas coinciding with rapid warming in the circum-North Atlantic region and the polar front shift from its zonal to meridional position 11.65 kyr B.P. As predicted by glaciological models, the ice sheet response to rapid North Atlantic warming was lagged by 400 years due to the thermal inertia of large ice sheets. The regional circum-North Atlantic Younger Dryas climate event is elevated to a global response through sea level changes, starting with the global slowdown in sea level rise during the Younger Dryas and culminating with MWP-1B. No meltwater pulses are evident at the initiation of the Younger Dryas climate event as is often speculated.

GHRSST Level 3C North Atlantic Regional (NAR) subskin Sea Surface Temperature from Metop/AVHRR (GDS V2) produced by OSI SAF (GDS version 2)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) dataset for the North Atlantic Region (NAR) derived from the Advanced Very High Resolution Radiometer...

Sea-level records from the U.S. mid-Atlantic constrain Laurentide Ice Sheet extent during Marine Isotope Stage 3.

Science.gov (United States)

Pico, T; Creveling, J R; Mitrovica, J X

2017-05-30

The U.S. mid-Atlantic sea-level record is sensitive to the history of the Laurentide Ice Sheet as the coastline lies along the ice sheet's peripheral bulge. However, paleo sea-level markers on the present-day shoreline of Virginia and North Carolina dated to Marine Isotope Stage (MIS) 3, from 50 to 35 ka, are surprisingly high for this glacial interval, and remain unexplained by previous models of ice age adjustment or other local (for example, tectonic) effects. Here, we reconcile this sea-level record using a revised model of glacial isostatic adjustment characterized by a peak global mean sea level during MIS 3 of approximately -40 m, and far less ice volume within the eastern sector of the Laurentide Ice Sheet than traditional reconstructions for this interval. We conclude that the Laurentide Ice Sheet experienced a phase of very rapid growth in the 15 kyr leading into the Last Glacial Maximum, thus highlighting the potential of mid-field sea-level records to constrain areal extent of ice cover during glacial intervals with sparse geological observables.

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

Science.gov (United States)

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

2017-08-15

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

Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Carbon dioxide (CO2) gas analyzer and other instruments from Atlantic Cartier in the Inner Sea - West Coast Scotland, Irish Sea and St. George's Channel and North Atlantic Ocean from 2015-09-12 to 2015-12-22 (NCEI Accession 0157236)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0157236 includes Surface underway, chemical, meteorological and physical data collected from Atlantic Cartier in the Inner Sea - West Coast Scotland,...

Were sea level changes during the Pleistocene in the South Atlantic Coastal Plain a driver of speciation in Petunia (Solanaceae)?

Science.gov (United States)

Ramos-Fregonezi, Aline M C; Fregonezi, Jeferson N; Cybis, Gabriela B; Fagundes, Nelson J R; Bonatto, Sandro L; Freitas, Loreta B

2015-05-20

Quaternary climatic changes led to variations in sea level and these variations played a significant role in the generation of marine terrace deposits in the South Atlantic Coastal Plain. The main consequence of the increase in sea level was local extinction or population displacement, such that coastal species would be found around the new coastline. Our main goal was to investigate the effects of sea level changes on the geographical structure and variability of genetic lineages from a Petunia species endemic to the South Atlantic Coastal Plain. We employed a phylogeographic approach based on plastid sequences obtained from individuals collected from the complete geographic distribution of Petunia integrifolia ssp. depauperata and its sister group. We used population genetics tests to evaluate the degree of genetic variation and structure among and within populations, and we used haplotype network analysis and Bayesian phylogenetic methods to estimate divergence times and population growth. We observed three major genetic lineages whose geographical distribution may be related to different transgression/regression events that occurred in this region during the Pleistocene. The divergence time between the monophyletic group P. integrifolia ssp. depauperata and its sister group (P. integrifolia ssp. integrifolia) was compatible with geological estimates of the availability of the coastal plain. Similarly, the origin of each genetic lineage is congruent with geological estimates of habitat availability. Diversification of P. integrifolia ssp. depauperata possibly occurred as a consequence of the marine transgression/regression cycles during the Pleistocene. In periods of high sea level, plants were most likely restricted to a refuge area corresponding to fossil dunes and granitic hills, from which they colonized the coast once the sea level came down. The modern pattern of lineage geographical distribution and population variation was established by a range

76 FR 56120 - Atlantic Highly Migratory Species; North and South Atlantic Swordfish Quotas

Science.gov (United States)

2011-09-12

... recreational fishing for swordfish in the Atlantic Ocean, including the Caribbean Sea and Gulf of Mexico, by... http://www.iccat.int/en/ . One swordfish measure adopted at the 2010 meeting, and one swordfish measure...

Decadal-scale teleconnection between South Atlantic SST and southeast Australia surface air temperature in austral summer

Science.gov (United States)

Xue, Jiaqing; Li, Jianping; Sun, Cheng; Zhao, Sen; Mao, Jiangyu; Dong, Di; Li, Yanjie; Feng, Juan

2018-04-01

Austral summer (December-February) surface air temperature over southeast Australia (SEA) is found to be remotely influenced by sea surface temperature (SST) in the South Atlantic at decadal time scales. In austral summer, warm SST anomalies in the southwest South Atlantic induce concurrent above-normal surface air temperature over SEA. This decadal-scale teleconnection occurs through the eastward propagating South Atlantic-Australia (SAA) wave train triggered by SST anomalies in the southwest South Atlantic. The excitation of the SAA wave train is verified by forcing experiments based on both linear barotropic and baroclinic models, propagation pathway and spatial scale of the observed SAA wave train are further explained by the Rossby wave ray tracing analysis in non-uniform basic flow. The SAA wave train forced by southwest South Atlantic warming is characterized by an anomalous anticyclone off the eastern coast of the Australia. Temperature diagnostic analyses based on the thermodynamic equation suggest anomalous northerly flows on western flank of this anticyclone can induce low-level warm advection anomaly over SEA, which thus lead to the warming of surface air temperature there. Finally, SST-forced atmospheric general circulation model ensemble experiments also demonstrate that SST forcing in the South Atlantic is associated with the SAA teleconnection wave train in austral summer, this wave train then modulate surface air temperature over SEA on decadal timescales. Hence, observations combined with numerical simulations consistently demonstrate the decadal-scale teleconnection between South Atlantic SST and summertime surface air temperature over SEA.

Twentieth century North Atlantic climate change. Part II: Understanding the effect of Indian Ocean warming

Energy Technology Data Exchange (ETDEWEB)

Hoerling, M.P.; Xu, T.; Bates, G.T. [Climate Diagnostics Center NOAA, Boulder, CO 80305-3328 (United States); Hurrell, J.W.; Phillips, A.S. [National Center for Atmospheric Research, Boulder, CO (United States)

2004-09-01

Ensembles of atmospheric general circulation model (AGCM) experiments are used in an effort to understand the boreal winter Northern Hemisphere (NH) extratropical climate response to the observed warming of tropical sea surface temperatures (SSTs) over the last half of the twentieth Century. Specifically, we inquire about the origins of unusual, if not unprecedented, changes in the wintertime North Atlantic and European climate that are well described by a linear trend in most indices of the North Atlantic Oscillation (NAO). The simulated NH atmospheric response to the linear trend component of tropic-wide SST change since 1950 projects strongly onto the positive polarity of the NAO and is a hemispheric pattern distinguished by decreased (increased) Arctic (middle latitude) sea level pressure. Progressive warming of the Indian Ocean is the principal contributor to this wintertime extratropical response, as shown through additional AGCM ensembles forced with only the SST trend in that sector. The Indian Ocean influence is further established through the reproducibility of results across three different models forced with identical, idealized patterns of the observed warming. Examination of the transient atmospheric adjustment to a sudden ''switch-on'' of an Indian Ocean SST anomaly reveals that the North Atlantic response is not consistent with linear theory and most likely involves synoptic eddy feedbacks associated with changes in the North Atlantic storm track. The tropical SST control exerted over twentieth century regional climate underlies the importance of determining the future course of tropical SST for regional climate change and its uncertainty. Better understanding of the extratropical responses to different, plausible trajectories of the tropical oceans is key to such efforts. (orig.)

GHRSST Level 3P North Atlantic Regional Subskin Sea Surface Temperature from the Advanced Very High Resolution Radiometer (AVHRR) on NOAA-19 (GDS version 1)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A Group for HIgh Resolution Sea Surface Temperature (GHRSST) dataset for the North Atlantic Region (NAR) from the Advanced Very High Resolution Radiometer (AVHRR) on...

GHRSST Level 3C North Atlantic Regional Subskin Sea Surface Temperature from the Advanced Very High Resolution Radiometer (AVHRR) on NOAA-19 (GDS version 2)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) dataset for the North Atlantic Region (NAR) from the Advanced Very High Resolution Radiometer (AVHRR) on...

Can preferred atmospheric circulation patterns over the North-Atlantic-Eurasian region be associated with arctic sea ice loss?

Science.gov (United States)

Crasemann, Berit; Handorf, Dörthe; Jaiser, Ralf; Dethloff, Klaus; Nakamura, Tetsu; Ukita, Jinro; Yamazaki, Koji

2017-12-01

In the framework of atmospheric circulation regimes, we study whether the recent Arctic sea ice loss and Arctic Amplification are associated with changes in the frequency of occurrence of preferred atmospheric circulation patterns during the extended winter season from December to March. To determine regimes we applied a cluster analysis to sea-level pressure fields from reanalysis data and output from an atmospheric general circulation model. The specific set up of the two analyzed model simulations for low and high ice conditions allows for attributing differences between the simulations to the prescribed sea ice changes only. The reanalysis data revealed two circulation patterns that occur more frequently for low Arctic sea ice conditions: a Scandinavian blocking in December and January and a negative North Atlantic Oscillation pattern in February and March. An analysis of related patterns of synoptic-scale activity and 2 m temperatures provides a synoptic interpretation of the corresponding large-scale regimes. The regimes that occur more frequently for low sea ice conditions are resembled reasonably well by the model simulations. Based on those results we conclude that the detected changes in the frequency of occurrence of large-scale circulation patterns can be associated with changes in Arctic sea ice conditions.

76 FR 61285 - Fisheries of the Caribbean, Gulf of Mexico, and South Atlantic; South Atlantic Snapper-Grouper...

Science.gov (United States)

2011-10-04

... recreational ACL overage. This action is necessary to reduce overfishing of the South Atlantic black sea bass... (AMs) be implemented to end overfishing and prevent overfishing from occurring. AMs are management... overfishing, including black sea bass, and AMs if these ACLs are reached or exceeded. The recreational ACL for...

Chlorophyll-a profiles collected by various vessels in the Atlantic Ocean and adjoining seas from 03/02/1961 to 10/21/1992 (NODC Accession 9300147)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Chlorophyll-a profiles were collected in the Atlantic Ocean and adjoining seas from March 2, 1961 to October 21, 1992. The data were collected by multiple...

Are North Atlantic Multidecadal SST Anomalies Westward Propagating?

NARCIS (Netherlands)

Feng, Qingyi; Dijkstra, Hendrik

2014-01-01

The westward propagation of sea surface temperature (SST) anomalies is one of the main characteristics of one of the theories of the Atlantic Multidecadal Oscillation. Here we use techniques from complex network modeling to investigate the existence of the westward propagation in the North Atlantic

An Anatomy of the 1960s Atlantic Cooling.

Science.gov (United States)

Hodson, Dan; Robson, Jon; Sutton, Rowan

2014-05-01

North Atlantic Sea Surface Temperatures (SSTs) exhibited pronounced multidecadal variability during the 20th Century. In particular, the North Atlantic SSTs exhibited a rapid warming between 1920 and 1940 followed by a rapid cooling between 1960 and 1980. SSTs outside the North Atlantic display a much smaller level of decadal variability over the 20th Century. This pattern of North Atlantic warming and cooling has been linked to subsequent changes in rainfall over the Sahel and Nordeste Brazil, Summertime North American Climate and Atlantic Hurricane Genesis. Several hypotheses for the rapid 1960s Atlantic cooling have been proposed, including a reduction in northward ocean heat transport due to a reduced Atlantic Meridional Overturning Circulation (AMOC) and the significant rise in anthropogenic sulphur dioxide emissions during the latter half of the 20th century. Here we examine the observed 1960s Atlantic cooling in more detail. We describe the evolution of the rapid cooling by constructing a detailed multivariate anatomy of the cooling period in order to illuminate the possible explanations and mechanisms involved. We show that the observed 1960s cooling began around 1964-68 in the Greenland-Iceland-Norway (GIN) seas, later spreading to the Atlantic Sub Polar Gyre and much of the subtropical Atlantic. This initial cooling of the Sub Polar Gyre is associated with a marked reduction in salinity (the Great Salinity Anomaly). The cooling peaked between 1972-76, extending into the Tropical North Atlantic. This period also saw the development of a significant Winter North-South Dipole Mean Sea Level Pressure dipole pattern reminiscent of a positive NAO (High over the Azores, Low over Iceland). The cooling then retreated back to higher latitudes during 1976:80. Our analysis demonstrates that the cooling of the North Atlantic during the 1960s cannot be understood as a simple thermodynamic response to aerosol induced reductions in shortwave radiation. Dynamical changes

Support of Publication Costs, Atlantic Meridional Overturning Circulation Special Issue of Deep Sea Research II Journal

Energy Technology Data Exchange (ETDEWEB)

Amy Honchar

2012-11-12

The contribution of funds from DOE supported publication costs of a special issue of Deep Sea Research arising from presentations at the First U.S. Atlantic Meridional Overturning Circulation (AMOC) Meeting held 4-6 May, 2009 to review the US implementation plan and its coordination with other monitoring activities. The special issue includes a total of 16 papers, including publications from three DOE-supported investigators (ie Sevellec, F., and A.V. Fedorov; Hu et. al., and Wan et. al.,). The special issue addresses DOE interests in understanding and simulation/modeling of abrupt climate change.

North atlantic multidecadal climate variability: An investigation of dominant time scales and processes

NARCIS (Netherlands)

Frankcombe, L.M.|info:eu-repo/dai/nl/304829838; von der Heydt, A.S.|info:eu-repo/dai/nl/245567526; Dijkstra, H.A.|info:eu-repo/dai/nl/073504467

2010-01-01

The issue of multidecadal variability in the North Atlantic has been an important topic of late. It is clear that there are multidecadal variations in several climate variables in the North Atlantic, such as sea surface temperature and sea level height. The details of this variability, in particular

Response of the Adriatic Sea to the atmospheric anomaly in 2003

Directory of Open Access Journals (Sweden)

B. Grbec

2007-05-01

Full Text Available Unusual weather conditions over the southern Europe and the Mediterranean area in 2003 significantly impacted the oceanographic properties of the Adriatic Sea. To document these changes, both in the atmosphere and the sea, anomalies from the normal climate were calculated. The winter 2003 was extremely cold, whereas the spring/summer period was extremely warm. The air temperature in June was more than 3 standard deviations above the average. On the other hand, precipitation and river runoff were extremely low between February and August. The response of the sea was remarkable, especially in surface salinity during spring and summer, with values at least one standard deviation above the average. Analysis of thermohaline properties in the middle Adriatic showed the importance of two phenomena responsible for the occurrence of exceptionally high salinity: (1 enhanced inflow of saline Levantine Intermediate Water (LIW in the Adriatic, and (2 extremely low precipitation and river runoff, accompanied with strong evaporation. Two large-scale atmospheric indices: NAOI (North Atlantic Oscillation Index and MOI (Mediterranean Oscillation Index, although generally correlated to the Adriatic climate, failed to describe anomalies in 2003. The air pressure gradients used for the definition of both indices significantly decreased in 2003 due to the presence of the high pressure areas over most of Europe and the northern Atlantic, and were actually responsible for the observed anomalies above and in the Adriatic.

GHRSST Level 3C North Atlantic Regional (NAR) subskin Sea Surface Temperature from SNPP/VIIRS (GDS V2) produced by OSI SAF (GDS version 2)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A regional Group for High Resolution Sea Surface Temperature (GHRSST) Level 3 Collated (L3C) dataset for the North Atlantic Region (NAR) based on retrievals from the...

The relative importance of ENSO and tropical Atlantic sea surface temperature anomalies for seasonal precipitation over South America: a numerical study

Science.gov (United States)

Pezzi, L. P.; Cavalcanti, I. F. A.

The role of tropical Atlantic sea surface temperature (SST) anomalies during ENSO episodes over northeast Brazil (Nordeste) is investigated using the CPTEC/COLA Atmospheric General Circulation Model (AGCM). Four sets of integrations are performed using SST in El Niño and La Niña (ENSO) episodes, changing the SST of the Atlantic Ocean. A positive dipole (SST higher than normal in the tropical North Atlantic and below normal in the tropical South Atlantic) and a negative dipole (opposite conditions), are set as the boundary conditions of SST in the Atlantic Ocean. The four experiments are performed using El Niño or La Niña SST in all oceans, except in the tropical Atlantic where the two phases of the SST dipole are applied. Five initial conditions were integrated in each case in order to obtain four ensemble results. The positive SST dipole over the tropical Atlantic Ocean and El Niño conditions over the Pacific Ocean resulted in dry conditions over the Nordeste. When the negative dipole and El Niño conditions over the Pacific Ocean were applied, the results showed precipitation above normal over the north of Nordeste. When La Niña conditions over Pacific Ocean were tested together with a negative dipole, positive precipitation anomalies occurred over the whole Nordeste. Using the positive dipole over the tropical Atlantic, the precipitation over Nordeste was below average. During La Niña episodes, the Atlantic Ocean conditions have a larger effect on the precipitation of Nordeste than the Pacific Ocean. In El Niño conditions, only the north region of Nordeste is affected by the Atlantic SST. Other tropical areas of South America show a change only in the intensity of anomalies. Central and southeast regions of South America are affected by the Atlantic conditions only during La Niña conditions, whereas during El Niño these regions are influenced only by conditions in the Pacific Ocean.

Mechanisms for decadal scale variability in a simulated Atlantic meridional overturning circulation

Energy Technology Data Exchange (ETDEWEB)

Medhaug, I.; Eldevik, T.; Furevik, T. [University of Bergen, Geophysical Institute, Bergen (Norway); Bjerknes Centre for Climate Research, Bergen (Norway); Langehaug, H.R. [Nansen Environmental and Remote Sensing Center, Bergen (Norway); Bjerknes Centre for Climate Research, Bergen (Norway); Bentsen, M. [Uni Bjerknes Centre, Uni Research, Bergen (Norway); Bjerknes Centre for Climate Research, Bergen (Norway)

2012-07-15

Variability in the Atlantic Meridional Overturning Circulation (AMOC) has been analysed using a 600-year pre-industrial control simulation with the Bergen Climate Model. The typical AMOC variability has amplitudes of 1 Sverdrup (1 Sv = 10{sup 6} m{sup 3} s{sup -1}) and time scales of 40-70 years. The model is reproducing the observed dense water formation regions and has very realistic ocean transports and water mass distributions. The dense water produced in the Labrador Sea (1/3) and in the Nordic Seas, including the water entrained into the dense overflows across the Greenland-Scotland Ridge (GSR; 2/3), are the sources of North Atlantic Deep Water (NADW) forming the lower limb of the AMOC's northern overturning. The variability in the Labrador Sea and the Nordic Seas convection is driven by decadal scale air-sea fluxes in the convective region that can be related to opposite phases of the North Atlantic Oscillation. The Labrador Sea convection is directly linked to the variability in AMOC. Linkages between convection and water mass transformation in the Nordic Seas are more indirect. The Scandinavian Pattern, the third mode of atmospheric variability in the North Atlantic, is a driver of the ocean's poleward heat transport (PHT), the overall constraint on northern water mass transformation. Increased PHT is both associated with an increased water mass exchange across the GSR, and a stronger AMOC. (orig.)

The role of local sea surface temperature pattern changes in shaping climate change in the North Atlantic sector

Science.gov (United States)

Hand, Ralf; Keenlyside, Noel S.; Omrani, Nour-Eddine; Bader, Jürgen; Greatbatch, Richard J.

2018-03-01

Beside its global effects, climate change is manifested in many regionally pronounced features mainly resulting from changes in the oceanic and atmospheric circulation. Here we investigate the influence of the North Atlantic SST on shaping the winter-time response to global warming. Our results are based on a long-term climate projection with the Max Planck Institute Earth System Model (MPI-ESM) to investigate the influence of North Atlantic sea surface temperature pattern changes on shaping the atmospheric climate change signal. In sensitivity experiments with the model's atmospheric component we decompose the response into components controlled by the local SST structure and components controlled by global/remote changes. MPI-ESM simulates a global warming response in SST similar to other climate models: there is a warming minimum—or "warming hole"—in the subpolar North Atlantic, and the sharp SST gradients associated with the Gulf Stream and the North Atlantic Current shift northward by a few a degrees. Over the warming hole, global warming causes a relatively weak increase in rainfall. Beyond this, our experiments show more localized effects, likely resulting from future SST gradient changes in the North Atlantic. This includes a significant precipitation decrease to the south of the Gulf Stream despite increased underlying SSTs. Since this region is characterised by a strong band of precipitation in the current climate, this is contrary to the usual case that wet regions become wetter and dry regions become drier in a warmer climate. A moisture budget analysis identifies a complex interplay of various processes in the region of modified SST gradients: reduced surface winds cause a decrease in evaporation; and thermodynamic, modified atmospheric eddy transports, and coastal processes cause a change in the moisture convergence. The changes in the the North Atlantic storm track are mainly controlled by the non-regional changes in the forcing. The impact of

The Opening of the Arctic-Atlantic Gateway: Tectonic, Oceanographic and Climatic Dynamics - an IODP Initiative

Science.gov (United States)

Geissler, Wolfram; Knies, Jochen

2016-04-01

The modern polar cryosphere reflects an extreme climate state with profound temperature gradients towards high-latitudes. It developed in association with stepwise Cenozoic cooling, beginning with ephemeral glaciations and the appearance of sea ice in the late middle Eocene. The polar ocean gateways played a pivotal role in changing the polar and global climate, along with declining greenhouse gas levels. The opening of the Drake Passage finalized the oceanographic isolation of Antarctica, some 40 Ma ago. The Arctic Ocean was an isolated basin until the early Miocene when rifting and subsequent sea-floor spreading started between Greenland and Svalbard, initiating the opening of the Fram Strait / Arctic-Atlantic Gateway (AAG). Although this gateway is known to be important in Earth's past and modern climate, little is known about its Cenozoic development. However, the opening history and AAG's consecutive widening and deepening must have had a strong impact on circulation and water mass exchange between the Arctic Ocean and the North Atlantic. To study the AAG's complete history, ocean drilling at two primary sites and one alternate site located between 73°N and 78°N in the Boreas Basin and along the East Greenland continental margin are proposed. These sites will provide unprecedented sedimentary records that will unveil (1) the history of shallow-water exchange between the Arctic Ocean and the North Atlantic, and (2) the development of the AAG to a deep-water connection and its influence on the global climate system. The specific overarching goals of our proposal are to study: (1) the influence of distinct tectonic events in the development of the AAG and the formation of deep water passage on the North Atlantic and Arctic paleoceanography, and (2) the role of the AAG in the climate transition from the Paleogene greenhouse to the Neogene icehouse for the long-term (~50 Ma) climate history of the northern North Atlantic. Getting a continuous record of the

Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the METEOR in the Caribbean Sea, North Atlantic Ocean and South Atlantic Ocean from 2002-06-07 to 2002-07-04 (NODC Accession 0115586)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115586 includes chemical, discrete sample, physical and profile data collected from METEOR in the Caribbean Sea, North Atlantic Ocean and South...

Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the SONNE in the Caribbean Sea, North Atlantic Ocean and South Atlantic Ocean from 2003-05-25 to 2003-06-13 (NODC Accession 0116705)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0116705 includes chemical, discrete sample, physical and profile data collected from SONNE in the Caribbean Sea, North Atlantic Ocean and South...

Low levels of very-long-chain n-3 PUFA in Atlantic salmon (Salmo salar) diet reduce fish robustness under challenging conditions in sea cages.

Science.gov (United States)

Bou, Marta; Berge, Gerd M; Baeverfjord, Grete; Sigholt, Trygve; Østbye, Tone-Kari; Ruyter, Bente

2017-01-01

The present study aimed to determine the minimum requirements of the essential n -3 fatty acids EPA and DHA in Atlantic salmon ( Salmo salar ) that can secure their health under challenging conditions in sea cages. Individually tagged Atlantic salmon were fed 2, 10 and 17 g/kg of EPA + DHA from 400 g until slaughter size (about 3·5 kg). The experimental fish reared in sea cages were subjected to the challenging conditions typically experienced under commercial production. Salmon receiving the lowest EPA + DHA levels showed lower growth rates in the earlier life stages, but no significant difference in final weights at slaughter. The fatty acid composition of various tissues and organs had remarkably changed. The decreased EPA + DHA in the different tissue membrane phospholipids were typically replaced by pro-inflammatory n -6 fatty acids, most markedly in the skin. The EPA + DHA levels were maintained at a higher level in the liver and erythrocytes than in the muscle, intestine and skin. After delousing at high water temperatures, the mortality rates were 63, 52 and 16 % in the salmon fed 2, 10 and 17 g/kg EPA + DHA. Low EPA + DHA levels also increased the liver, intestinal and visceral fat amount, reduced intervertebral space and caused mid-intestinal hyper-vacuolisation. Thus, 10 g/kg EPA + DHA in the Atlantic salmon diet, a level previously regarded as sufficient, was found to be too low to maintain fish health under demanding environmental conditions in sea cages.

Geological and Structural evolution of the Eurasia Africa plate boundary in the Gulf of Cadiz Central Eastern Atlantic Sea.

OpenAIRE

D’Oriano, Filippo

2010-01-01

Iberia Africa plate boundary, cross, roughly W-E, connecting the eastern Atlantic Ocean from Azores triple junction to the Continental margin of Morocco. Relative movement between the two plate change along the boundary, from transtensive near the Azores archipelago, through trascurrent movement in the middle at the Gloria Fracture Zone, to transpressive in the Gulf of Cadiz area. This study presents the results of geophysical and geological analysis on the plate boundary area offshore Gibral...

77 FR 33443 - Mid-Atlantic Fishery Management Council (MAFMC); Meeting

Science.gov (United States)

2012-06-06

...-Atlantic Fishery Management Council's (Council) Summer Flounder, Scup, Black Sea Bass, and Bluefish... Summer Flounder, Scup, Black Sea Bass, and Bluefish. Although non-emergency issues not contained in this...

Plasma Vitellogenin in Free-Ranging Loggerhead Sea Turtles (Caretta caretta of the Northwest Atlantic Ocean

Directory of Open Access Journals (Sweden)

Kimberly Smelker

2014-01-01

Full Text Available Vitellogenin is the egg yolk precursor protein produced by oviparous vertebrates. As endogenous estrogen increases during early reproductive activity, hepatic production of vitellogenin is induced and is assumed to be complete in female sea turtles before the first nesting event. Until the present study, innate production of vitellogenin has not been described in free-ranging sea turtles. Our study describes circulating concentrations of vitellogenin in loggerhead sea turtles (Caretta caretta from the Northwest Atlantic Ocean. We collected blood samples from juveniles and adults via in-water captures off the coast of the Southeast USA from May to August, and from nesting females in June and July at Hutchinson Island, Florida. All samples were analyzed using an in-house ELISA developed specifically to measure Caretta caretta vitellogenin concentration. As expected, plasma vitellogenin declined in nesting turtles as the nesting season progressed, although it still remained relatively elevated at the end of the season. In addition, mean vitellogenin concentration in nesting turtles was 1,000 times greater than that measured in samples from in-water captures. Our results suggest that vitellogenesis may continue throughout the nesting season, albeit at a decreasing rate. Further, vitellogenin detected in turtles captured in-water may have resulted from exposure to endocrine disrupting chemicals.

Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from underway - surface observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from the Atlantic Companion in the Inner Sea - West Coast Scotland, Irish Sea and St. George's Channel and North Atlantic Ocean from 2006-06-11 to 2007-11-05 (NODC Accession 0115226)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115226 includes chemical, meteorological, physical and underway - surface data collected from Atlantic Companion in the Inner Sea - West Coast...

Risk assessment reveals high exposure of sea turtles to marine debris in French Mediterranean and metropolitan Atlantic waters

Science.gov (United States)

Darmon, Gaëlle; Miaud, Claude; Claro, Françoise; Doremus, Ghislain; Galgani, François

2017-07-01

Debris impact on marine wildlife has become a major issue of concern. Mainy species have been identified as being threatened by collision, entanglement or ingestion of debris, generally plastics, which constitute the predominant part of the recorded marine debris. Assessing sensitive areas, where exposure to debris are high, is thus crucial, in particular for sea turtles which have been proposed as sentinels of debris levels for the Marine Strategy Framework Directive and for the Unep-MedPol convention. Our objective here was to assess sea turtle exposure to marine debris in the 3 metropolitan French fronts. Using aerial surveys performed in the Channel, the Atlantic and the Mediterranean regions in winter and summer 2011-2012, we evaluated exposure areas and magnitude in terms of spatial overlap, encounter probability and density of surrounding debris at various spatial scales. Major overlapping areas appeared in the Atlantic and Mediterranean fronts, concerning mostly the leatherback and the loggerhead turtles respectively. The probability for individuals to be in contact with debris (around 90% of individuals within a radius of 2 km) and the density of debris surrounding individuals (up to 16 items with a radius of 2 km, 88 items within a radius of 10 km) were very high, whatever the considered spatial scale, especially in the Mediterranean region and during the summer season. The comparison of the observed mean debris density with random distribution suggested that turtles selected debris areas. This may occur if both debris and turtles drift to the same areas due to currents, if turtles meet debris accidentally by selecting high food concentration areas, and/or if turtles actively seek debris out, confounding them with their preys. Various factors such as species-specific foraging strategies or oceanic features which condition the passive diffusion of debris, and sea turtles in part, may explain spatio-temporal variations in sensitive areas. Further research

Differential response of continental stock complexes of Atlantic salmon (Salmo salar) to the Atlantic Multidecadal Oscillation

Science.gov (United States)

Friedland, Kevin D.; Shank, Burton V.; Todd, Christopher D.; McGinnity, Philip; Nye, Janet A.

2014-05-01

Atlantic salmon, Salmo salar, in the North Atlantic are managed as a set of population complexes distributed in North America and Europe. In recent years, these complexes have experienced reduced marine survival and many populations within the complexes are at risk, especially those at the southern ends of the species amphi-Atlantic range. Atlantic salmon is an anadromous fish dividing its life history between residence in freshwater and the marine environment. The freshwater portion of the life history includes spawning and the rearing of juveniles where in-river production has tended to be relatively stable, whereas the first year at sea, termed the post-smolt year, is characterized by more variable rates of mortality. Although their habitats are widely separated geographically along the North Atlantic seaboards, strong recruitment coherence exists between North American and European stock complexes. This recruitment coherence is correlated with ocean temperature variation associated with the Atlantic Multidecadal Oscillation (AMO). The North Atlantic Oscillation (NAO) appears to be relatively unimportant as a driver of salmon abundance. The mechanism determining the link between AMO-related thermal variation and abundance appears to differ fundamentally for the two continental stock groupings. Whereas ocean climate variability during the first springtime months of juvenile salmon migration to sea appears to be important to the survival of North American stocks, summer climate variation appears to be central to adult recruitment variation for European stocks. This contrast in seasonal effects appears to be related to the varying roles of predation pressure and size-related mortality on the continental stock complexes. The anticipated warming due to global climate change will impose thermal conditions on salmon populations outside historical context and challenge the ability of many populations to persist.

Salinity Trends within the Upper Layers of the Subpolar North Atlantic

Science.gov (United States)

Tesdal, J. E.; Abernathey, R.; Goes, J. I.; Gordon, A. L.; Haine, T. W. N.

2017-12-01

Examination of a range of salinity products collectively suggest widespread freshening of the North Atlantic from the mid-2000 to the present. Monthly salinity fields reveal negative trends that differ in magnitude and significance between western and eastern regions of the North Atlantic. These differences can be attributed to the large negative interannual excursions in salinity in the western subpolar gyre and the Labrador Sea, which are not apparent in the central or eastern subpolar gyre. This study demonstrates that temporal trends in salinity in the northwest (including the Labrador Sea) are subject to mechanisms that are distinct from those responsible for the salinity trends in central and eastern North Atlantic. In the western subpolar gyre a negative correlation between near surface salinity and the circulation strength of the subpolar gyre suggests that negative salinity anomalies are connected to an intensification of the subpolar gyre, which is causing increased flux of freshwater from the East Greenland Current and subsequent transport into the Labrador Sea during the melting season. Analyses of sea surface wind fields suggest that the strength of the subpolar gyre is linked to the North Atlantic Oscillation and Arctic Oscillation-driven changes in wind stress curl in the eastern subpolar gyre. If this trend of decreasing salinity continues, it has the potential to enhance water column stratification, reduce vertical fluxes of nutrients and cause a decline in biological production and carbon export in the North Atlantic Ocean.

Into the deep blue sea: Commons theory and international governance of Atlantic Bluefin Tuna

Directory of Open Access Journals (Sweden)

Graham Epstein

2014-08-01

Full Text Available The need to understand how to sustainably govern oceanic fisheries has become increasingly urgent as their contribution to global food security and livelihoods are threatened by declining stocks. Atlantic Bluefin Tuna (ABFT is a prominent example of the complexities associated with widely distributed oceanic resources, extending in this case to include much of the North-Atlantic and Mediterranean Sea. This distribution has led to limited attention from commons theorists that tend to focus on small-scale social ecological systems. Therefore in order to explore the fit between theories of the commons developed in small-scale systems, we apply the Social-Ecological Systems Meta-Analysis Database (SESMAD to systematically analyze ABFT governance over a 22 year period. The results, which focus on the effects of resource characteristics, broadly correspond to the expectations of commons theory. Interestingly, however, the addition of resource storage in the form of ABFT ranches appears to be contributing to unsustainable harvests. This stands in contrast to previous findings in the commons literature that storage tends to enhance prospects for sustainable governance. Therefore several alternative hypotheses are developed by comparing and contrasting attributes of ABFT and canal irrigation storage. These hypotheses may be used in future research to evaluate the conditions in which storage enhances prospects for sustainable governance.

GHRSST Level 2P North Atlantic Regional Bulk Sea Surface Temperature from the Advanced Very High Resolution Radiometer (AVHRR) on the NOAA-18 satellite (GDS version 1)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A Group for HIgh Resolution Sea Surface Temperature (GHRSST) dataset for the North Atlantic Region (NAR) from the Advanced Very High Resolution Radiometer (AVHRR) on...

GHRSST Level 2P North Atlantic Regional Bulk Sea Surface Temperature from the Advanced Very High Resolution Radiometer (AVHRR) on the NOAA-17 satellite (GDS version 1)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) dataset for the North Atlantic Region (NAR) from the Advanced Very High Resolution Radiometer (AVHRR) on...

GHRSST Level 2P North Atlantic Regional Bulk Sea Surface Temperature from the Advanced Very High Resolution Radiometer (AVHRR) on the NOAA-16 satellite (GDS version 1)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A Group for HIgh Resolution Sea Surface Temperature (GHRSST) dataset for the North Atlantic Region (NAR) from the Advanced Very High Resolution Radiometer (AVHRR) on...

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

Inventory, distribution, and origin of aliphatic and polyaromatic hydrocarbons in sea water, the surface microlayer, and the aerosols in the tropical Eastern Atlantic

Energy Technology Data Exchange (ETDEWEB)

Marty, J C; Saliot, A; Tissier, M J

1978-03-20

Hydrocarbons have been analyzed in several samples from ''Midlante'' cruise, Cape Verde islands-Canary islands, in the Eastern tropical Atlantic: subsurface water, sea surface microlayer collected by a metallic screen and aerosols collected by filtration of large air volumes at about 12 m. above the sea surface. Detailed analysis of aliphatic and polyaromatic hydrocarbons has been made by computerized gas chromatography/mass spectrometry. This study of the air/sea interface indicates a discontinuity in hydrocarbon composition between the underlying water and the microlayer and a similarity between the surface microlayer and the aerosols. The origin of the collected aerosols is essentially marine with a minor terrestrial contribution. The hydrocarbon pattern shows that, superimposed on the typical marine components, a contribution from smokes of natural and industrial origin and/or from pollution associated with crude oil sea slicks is present.

GHRSST Level 3P North Atlantic Regional Subskin Sea Surface Temperature from the Advanced Very High Resolution Radiometer (AVHRR) on the MetOp-A satellite (GDS version 1)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A Group for HIgh Resolution Sea Surface Temperature (GHRSST) dataset for the North Atlantic Region (NAR) from the Advanced Very High Resolution Radiometer (AVHRR) on...

Seasonal variation in biomarkers in blue mussel (Mytilus edulis), Icelandic scallop (Chlamys islandica) and Atlantic cod (Gadus morhua)-Implications for environmental monitoring in the Barents Sea

Energy Technology Data Exchange (ETDEWEB)

Nahrgang, J., E-mail: jasmine.m.nahrgang@uit.no [Akvaplan-niva, FRAM Centre, NO-9296 Tromso (Norway); Brooks, S.J. [Norwegian Institute for Water Research (NIVA), NO-0349 Oslo (Norway); Evenset, A. [Akvaplan-niva, FRAM Centre, NO-9296 Tromso (Norway); Camus, L. [Akvaplan-niva, FRAM Centre, NO-9296 Tromso (Norway); University Centre In Svalbard (UNIS), NO-9171 Longyearbyen (Norway); Jonsson, M.; Smith, T.J. [Akvaplan-niva, FRAM Centre, NO-9296 Tromso (Norway); Lukina, J. [Akvaplan-niva, FRAM Centre, NO-9296 Tromso (Norway); University of Tromso, Faculty of Biosciences, Fisheries and Economics, Department of Arctic and Marine Biosciences, NO-9037 Tromso (Norway); Frantzen, M. [Akvaplan-niva, FRAM Centre, NO-9296 Tromso (Norway); Giarratano, E. [Centro Nacional Patagonico (CENPAT-CONICET), AR-9120 Puerto Madryn (Argentina); Renaud, P.E. [Akvaplan-niva, FRAM Centre, NO-9296 Tromso (Norway); University Centre In Svalbard (UNIS), NO-9171 Longyearbyen (Norway)

2013-02-15

In the Barents Sea, the limited data on biological relevant indicators and their responses to various anthropogenic stressors have hindered the development of a consistent scientific basis for selecting indicator species and developing practical procedures for environmental monitoring. Accordingly, the main aim of the present study was to develop a common set of baseline values for contaminants and biomarkers in three species, and to identify their strengths and limitations in monitoring of the Barents Sea. Blue mussel (Mytilus edulis), Icelandic scallop (Chlamys islandica) and Atlantic cod (Gadus morhua) were sampled from a north Norwegian fjord in March, June, September and December 2010. Digestive glands from the bivalve species and liver from Atlantic cod were analysed for biomarkers of oxidative stress (catalase [CAT], glutathione peroxidase [GPX], glutathione-S-transferase activities [GST], lipid peroxidation as thiobarbituric reactive substances [TBARS] and total oxyradical scavenging capacity [TOSC]), biotransformation (ethoxyresorufine-O-deethylase activity [EROD]) and general stress (lysosomal membrane stability [LMS]). Concentrations of polycyclic aromatic hydrocarbons (PAHs) and metals in the bivalves and PAH metabolites in fish bile were quantified. Finally, energy reserves (total lipids, proteins and carbohydrates) and electron transport system (ETS) activity in the digestive gland of the bivalves and liver of Atlantic cod provided background information for reproductive cycle and general physiological status of the organisms. Blue mussel and Icelandic scallop showed very similar trends in biological cycle, biomarker expression and seasonality. Biomarker baselines in Atlantic cod showed weaker seasonal variability. However, important biological events may have been undetected due to the large time intervals between sampling occasions. Physiological biomarkers such as energy reserves and ETS activity were recommended as complementary parameters to the

Effects of the North Atlantic Oscillation and wind waves on salt marsh dynamics in the Danish Wadden Sea

DEFF Research Database (Denmark)

Kim, Daehyun; Grant, William E.; Cairns, David M.

2013-01-01

Long-term eustatic sea-level variation has been recognized as a primary factor affecting the hydrological and geomorphic dynamics of salt marshes. However, recent studies suggest that wind waves influenced by atmospheric oscillations also may play an important role in many coastal areas. Although...... this notion has been conceptually introduced for the Wadden Sea, no modeling attempts have been made yet. As a proof of concept, this study developed a simulation model using the commercially available STELLAA (R) software, based on long-term data on water level and sedimentation collected at a back......-barrier marsh on the Skallingen peninsula in Denmark. In the model, the frequency (number year(-1)) of wind-driven extreme high water level (HWL) events (> 130 cm Danish Ordnance Zero) was simulated in terms of the North Atlantic Oscillation (NAO) index. Then, surface accretion (cm year(-1)) and submergence...

North Atlantic 20th century multidecadal variability in coupled climate models: sea surface temperature and ocean overturning circulation

Directory of Open Access Journals (Sweden)

I. Medhaug

2011-06-01

Full Text Available Output from a total of 24 state-of-the-art Atmosphere-Ocean General Circulation Models is analyzed. The models were integrated with observed forcing for the period 1850–2000 as part of the Intergovernmental Panel on Climate Change (IPCC Fourth Assessment Report. All models show enhanced variability at multi-decadal time scales in the North Atlantic sector similar to the observations, but with a large intermodel spread in amplitudes and frequencies for both the Atlantic Multidecadal Oscillation (AMO and the Atlantic Meridional Overturning Circulation (AMOC. The models, in general, are able to reproduce the observed geographical patterns of warm and cold episodes, but not the phasing such as the early warming (1930s–1950s and the following colder period (1960s–1980s. This indicates that the observed 20th century extreme in temperatures are due to primarily a fortuitous phasing of intrinsic climate variability and not dominated by external forcing. Most models show a realistic structure in the overturning circulation, where more than half of the available models have a mean overturning transport within the observed estimated range of 13–24 Sverdrup. Associated with a stronger than normal AMOC, the surface temperature is increased and the sea ice extent slightly reduced in the North Atlantic. Individual models show potential for decadal prediction based on the relationship between the AMO and AMOC, but the models strongly disagree both in phasing and strength of the covariability. This makes it difficult to identify common mechanisms and to assess the applicability for predictions.

The subpolar North Atlantic - Response to North Atlantic oscillation like forcing and Influence on the Atlantic meridional overturning circulation

Science.gov (United States)

Lohmann, Katja; Drange, Helge; Jungclaus, Johann

2010-05-01

The extent and strength of the North Atlantic subpolar gyre (SPG) changed rapidly in the mid-1990s, going from large and strong in 1995 to substantially weakened in the following years. The abrupt change in the intensity of the SPG is commonly linked to the reversal of the North Atlantic Oscillation (NAO) index, changing from strong positive to negative values, in the winter 1995/96. In this study we investigate the impact of the initial SPG state on its subsequent behavior by means of an ocean general circulation model driven by NCEP-NCAR reanalysis fields. Our sensitivity integrations suggest that the weakening of the SPG cannot be explained by the change in the atmospheric forcing alone. Rather, for the time period around 1995, the SPG was about to weaken, irrespective of the actual atmospheric forcing, due to the ocean state governed by the persistently strong positive NAO during the preceding seven years (1989 to 1995). Our analysis indicates that it was this preconditioning of the ocean, in combination with the sudden drop in the NAO in 1995/96, that lead to the strong and rapid weakening of the SPG in the second half of the 1990s. In the second part, the sensitivity of the low-frequency variability of the Atlantic meridional overturning circulation to changes in the subpolar North Atlantic is investigated using a 2000 year long control integration as well as sensitivity experiments with the MPI-M Earth System Model. Two 1000 year long sensitivity experiments will be performed, in which the low-frequency variability in the overflow transports from the Nordic Seas and in the subpolar deep water formation rates is suppressed respectively. This is achieved by nudging temperature and salinity in the GIN Sea or in the subpolar North Atlantic (up to about 1500m depth) towards a monthly climatology obtained from the last 1000 years of the control integration.

Assessing extreme sea levels due to tropical cyclones in the Atlantic basin

Science.gov (United States)

Muis, Sanne; Lin, Ning; Verlaan, Martin; Winsemius, Hessel; Vatvani, Deepak; Ward, Philip; Aerts, Jeroen

2017-04-01

provide reliable probabilities of surge levels for the entire Atlantic basin. References Demuth, J., DeMaria, M., and Knaff, J.A. (2006). Improvement of advanced microwave sounder unit tropical cyclone intensity and size estimation algorithms. Journal of Applied Meteorology., 45, pp. 1573-1581. Emanuel, K., Ravela, S., Vivant, E. and Risi, C. (2006). A statistical deterministic approach to hurricane risk assessment. Bulletin of the American Meteorological Society, 87(3), pp.299-314. Holland, G.J. (1980). An analytic model of the wind and pressure profiles in hurricanes. Monthly Weather Review, 108(8), pp.1212-1218. Lin, N. and D. Chavas (2012). On hurricane parametric wind and applications in storm surge modeling. Journal of Geophysical Research - Atmospheres. 117. doi:10.1029/2011jd017126. Muis, S., Verlaan, M., Winsemius, H. C., Aerts, J. C. J. H., & Ward, P. J. (2016). A global reanalysis of storm surge and extreme sea levels. Nature Communications, 7(7:11969), 1-11.

Assemblages of deep-sea fishes on the middle slope off Northwest Africa (26°-33° N, eastern Atlantic)

Science.gov (United States)

Pajuelo, J. G.; Seoane, J.; Biscoito, M.; Freitas, M.; González, J. A.

2016-12-01

The structure and composition of deep-sea fish assemblages living on the middle slope off NW Africa (26-33° N) were investigated. Data were collected by six commercial trawlers during experimental fishing (1027 hauls) at depths between 800 and 1515 m. A total of 1,115,727 fish specimens, belonging to 37 families and 96 species (24 Elasmobranchii, 5 Holocephali, and 67 Actinopteri) were collected with bottom trawls. The deep-sea demersal fish fauna off NW Africa is dominated by fishes of the family Macrouridae, followed by the Moridae and Alepocephalidae families. The main abundant species were Trachyrincus scabrus, Bathygadus favosus, Mora moro, Alepocephalus productus, Nezumia aequalis and Bathygadus melanobranchus. PERMANOVA analysis showed differences in demersal fish assemblages among bottom types, depth strata and between areas (north and south of parallel 30° N), with the area being the most influential factor followed by the type of substrate. PERMANOVAs computed separately for each area showed significant differences among the bottom types and depths in both areas. SIMPER analysis revealed that B. melanobranchus and B. favosus, which occurred at higher abundances in the area ≥30° N, were the species that were best discriminated between areas; whilst T. scabrus and M. moro occurred at higher abundances in the area <30° N. N. aequalis, B. favosus, B. melanobranchus, Deania hystricosa, Aphanopus intermedius, Coelorinchus labiatus and Halosaurus johnsonianus were restricted or more abundant in the area ≥30° N, and functioned as the discriminating species that most contributed to the average dissimilarity between areas. T. scabrus, M. moro, Alepocephalus productus and Alepocephalus bairdii were more abundant in the area <30° N. The standardized mean abundance (in number of individuals/km2) showed a decreasing pattern: i) with depth in both areas, north and south of parallel 30° N, and ii) with depth on each type of substrate, except on cold coral

Air/sea DMS gas transfer in the North Atlantic: evidence for limited interfacial gas exchange at high wind speed

Science.gov (United States)

Bell, T. G.; De Bruyn, W.; Miller, S. D.; Ward, B.; Christensen, K.; Saltzman, E. S.

2013-05-01

Shipboard measurements of eddy covariance DMS air/sea fluxes and seawater concentration were carried out in the North Atlantic bloom region in June/July 2011. Gas transfer coefficients (k660) show a linear dependence on mean horizontal wind speed at wind speeds up to 11 m s-1. At higher wind speeds the relationship between k660 and wind speed weakens. At high winds, measured DMS fluxes were lower than predicted based on the linear relationship between wind speed and interfacial stress extrapolated from low to intermediate wind speeds. In contrast, the transfer coefficient for sensible heat did not exhibit this effect. The apparent suppression of air/sea gas flux at higher wind speeds appears to be related to sea state, as determined from shipboard wave measurements. These observations are consistent with the idea that long waves suppress near surface water side turbulence, and decrease interfacial gas transfer. This effect may be more easily observed for DMS than for less soluble gases, such as CO2, because the air/sea exchange of DMS is controlled by interfacial rather than bubble-mediated gas transfer under high wind speed conditions.

The Teleconnection of the Tropical Atlantic to Indo-Pacific Sea Surface Temperatures on Inter-Annual to Centennial Time Scales: A Review of Recent Findings

Directory of Open Access Journals (Sweden)

Fred Kucharski

2016-02-01

Full Text Available In this paper, the teleconnections from the tropical Atlantic to the Indo-Pacific region from inter-annual to centennial time scales will be reviewed. Identified teleconnections and hypotheses on mechanisms at work are reviewed and further explored in a century-long pacemaker coupled ocean-atmosphere simulation ensemble. There is a substantial impact of the tropical Atlantic on the Pacific region at inter-annual time scales. An Atlantic Niño (Niña event leads to rising (sinking motion in the Atlantic region, which is compensated by sinking (rising motion in the central-western Pacific. The sinking (rising motion in the central-western Pacific induces easterly (westerly surface wind anomalies just to the west, which alter the thermocline. These perturbations propagate eastward as upwelling (downwelling Kelvin-waves, where they increase the probability for a La Niña (El Niño event. Moreover, tropical North Atlantic sea surface temperature anomalies are also able to lead La Niña/El Niño development. At multidecadal time scales, a positive (negative Atlantic Multidecadal Oscillation leads to a cooling (warming of the eastern Pacific and a warming (cooling of the western Pacific and Indian Ocean regions. The physical mechanism for this impact is similar to that at inter-annual time scales. At centennial time scales, the Atlantic warming induces a substantial reduction of the eastern Pacific warming even under CO2 increase and to a strong subsurface cooling.

Sea Turtle Research Program Summary Report

National Research Council Canada - National Science Library

1997-01-01

The USACE Sea Turtle Research Program (STRP) was conducted to minimize the risk to sea turtle populations in channels along the southeast Atlantic region of the United States from hopper-dredging activities...

Comparative biology and population mixing among local, coastal and offshore Atlantic herring (Clupea harengus) in the North Sea, Skagerrak, Kattegat and western Baltic

Science.gov (United States)

Slotte, Aril; Johannessen, Arne; Kvamme, Cecilie; Clausen, Lotte Worsøe; Nash, Richard D. M.

2017-01-01

The population structure of Atlantic herring (Clupea harengus) from 13 local, coastal and offshore areas of the North Sea, Skagerrak, Kattegat and western Baltic (northeast Atlantic) was studied using biological and environmental data from 1970–2015. The objective was to identify distinct populations by comparing variability in the temporal and spatial phenotypic characteristics and evaluate the potential for mixing of populations in time and space. The populations varied in biological characteristics such as mean vertebral counts (VS), growth and maturity ogives. Generalized additive models indicated temporally stable VS in the North Sea and western Baltic, whereas intra-annual temporal variation of VS occurred in other areas. High variability of VS within a population was not affected by environmental factors such as temperature and salinity. Consequently, seasonal VS variability can be explained by the presence or absence of herring populations as they migrate between areas. The three main populations identified in this paper correspond to the three managed stocks in this area: Norwegian spring spawners (NSS), western Baltic spring spawners (WBSS) and North Sea autumn spawners (NSAS). In addition, several local populations were identified in fjords or lakes along the coast, but our analyses could not detect direct mixing of local populations with the three main populations. Our results highlight the importance of recognizing herring dynamics and understanding the mixing of populations as a challenge for management of herring. PMID:29084258

GHRSST Level 3C North Atlantic Regional (NAR) subskin Sea Surface Temperature from SNPP/VIIRS and Metop-A/AVHRR (GDS V2) produced by OSI SAF (GDS version 2)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) dataset for the North Atlantic Region (NAR) derived from the Advanced Very High Resolution Radiometer...

Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the KNORR in the Caribbean Sea, North Atlantic Ocean and South Atlantic Ocean from 1982-12-01 to 1983-02-18 (NODC Accession 0116706)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0116706 includes chemical, discrete sample, physical and profile data collected from KNORR in the Caribbean Sea, North Atlantic Ocean and South...

Stock structure of Atlantic herring Clupea harengus in the Norwegian Sea and adjacent waters

DEFF Research Database (Denmark)

Pampoulie, Christophe; Slotte, Aril; Oskarsson, Guomundur J.

2015-01-01

The genetic structure of Atlantic herring Clupea harengus L. was investigated in its north-easterly distribution in the Norwegian Sea and adjacent waters, using 23 neutral and one non-neutral (Cpa111) microsatellite loci. Fish from the suspected 2 main populations-the Norwegian spring......-spawning herring (NSSH) and the Icelandic summer-spawning herring (ISSH)-were collected at spawning locations in their respective spawning seasons from 2009 to 2012. Samples were also collected from Norwegian autumn spawning locations, from different local Norwegian fjords such as the inner part...... of Trondheimsfjorden, Lindas pollene, Landvikvannet and Lusterfjorden, as well as from suspected Faroese spawning components. The observed level of genetic differentiation was significant but low (F-ST = 0.007) and mostly attributable to the differentiation of the local Norwegian fjord populations. The locus Cpa111...

Caribbean Sea rainfall variability during the rainy season and relationship to the equatorial Pacific and tropical Atlantic SST

Energy Technology Data Exchange (ETDEWEB)

Wu, Renguang [Institute of Global Environment and Society, Center for Ocean-Land-Atmosphere Studies, Calverton, MD (United States); Kirtman, Ben P. [University of Miami, Rosenstiel School of Marine and Atmospheric Sciences, Miami, FL (United States)

2011-10-15

The present study investigates the Caribbean Sea rainfall variability during the early and late rainy seasons and its association with sea surface temperature (SST) and air-sea interaction based on observational estimates, the NCEP Climate Forecast System (CFS) and Global Forecast System (GFS) simulations, and the CFS retrospective forecasts. Analysis of the observational estimates indicates that air-sea interaction is important over the Caribbean Sea, whereas the atmospheric forcing of SST dominates over the Gulf of Mexico. The CFS simulation captures the basic elements of this observed air-sea relationship. The GFS simulation produces spurious SST forcing of the atmosphere over the Gulf of Mexico largely due to prescribing SST. The CFS forecasts capture the air-sea relationship in the late rainy season (August-October), but cannot reproduce the SST forcing of atmosphere over the Caribbean Sea in the early rainy season (May-July). An empirical orthogonal function (EOF) analysis indicates that the leading modes of percent anomalies of the rainy season precipitation have the largest loading in the southern Caribbean Sea in observations. The model simulations and forecasts skillfully reproduce the spatial pattern, but not the temporal evolution. The Caribbean Sea rainfall variability in the early rainy season is mainly due to the tropical North Atlantic (TNA) SST anomalies in observations, is contributed by both the TNA and eastern equatorial Pacific (EEP) SST anomalies in the CFS simulation, and has an overly large impact from the EEP SST anomalies in the GFS simulation and the CFS forecasts. The observed Caribbean Sea rainfall variability in the late rainy season has a leading impact from the EEP SST anomalies, with a secondary contribution from the TNA SST anomalies. In comparison, the model simulations and forecasts overestimate the impacts of the EEP SST anomalies due to an earlier development and longer duration of the El Nino-Southern Oscillation in the CFS

Concentrations and distributions of metals in tissues of stranded green sea turtles (Chelonia mydas) from the southern Atlantic coast of Brazil

International Nuclear Information System (INIS)

da Silva, Cinthia Carneiro; Varela, Antonio Sergio; Barcarolli, Indianara Fernanda; Bianchini, Adalto

2014-01-01

Silver (Ag), cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) concentrations were analyzed in tissues of juvenile green sea turtles (Chelonia mydas) found stranded along the southern Atlantic coast in Brazil. Green sea turtles were collected (n = 29), measured (curved carapace length: CCL) and had their muscle, liver, and kidney dissected for metal concentration measurements. Sex was identified in 18 individuals (10 females and 8 males) through gonad histology. No gender differences in CCL and tissue metal concentrations were observed. In the muscle, there was a negative correlation between CCL and Cd and Cu concentrations. Metal concentrations were lower in the muscle than in the liver and kidney. Zn concentration in the muscle was the highest of all metals analyzed (16.6 mg/kg). The kidney showed the highest concentrations of Pb, Cd and Zn (5.4, 28.3 and 54.3 mg/kg, respectively), while the liver had the highest values of Ag and Cu (0.8 and 100.9 mg/kg, respectively). Tissue Ag, Zn and Cd concentrations were similar to those found in green sea turtles from other regions while Cu and Pb values were elevated, likely due to the metal-rich water and sediment reported in the collection area. In the liver and kidney, concentrations of non-essential (Ag, Cd and Pb) and essential (Cu or Zn) metals were positively correlated, likely due to an induced metallothionein synthesis to protect tissue against the toxic effect of metals. This is the first study to report and correlate the concentrations of essential and non-essential metals in tissues of green sea turtles in the Brazilian southern Atlantic coast, an important feeding and developing area for this turtle species. - Highlights: •Juvenile female and male green sea turtles have similar concentrations of metals. •Kidney accumulated more Cd, Pb and Zn while liver accumulated more Ag and Cu. •Cu and Pb concentrations are elevated in liver of sea turtles from southern Brazil. •Concentrations of Cd and Cu in

Concentrations and distributions of metals in tissues of stranded green sea turtles (Chelonia mydas) from the southern Atlantic coast of Brazil

Energy Technology Data Exchange (ETDEWEB)

da Silva, Cinthia Carneiro [Programa de Pós-Graduação em Ciências Fisiológicas – Fisiologia Animal Comparada, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande, Av. Itália km 8, 96203-900, Rio Grande, Rio Grande do Sul (Brazil); Varela, Antonio Sergio; Barcarolli, Indianara Fernanda [Instituto de Ciências Biológicas, Universidade Federal do Rio Grande, Av. Itália km 8, 96203-900, Rio Grande, Rio Grande do Sul (Brazil); Bianchini, Adalto, E-mail: adaltobianchini@furg.br [Programa de Pós-Graduação em Ciências Fisiológicas – Fisiologia Animal Comparada, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande, Av. Itália km 8, 96203-900, Rio Grande, Rio Grande do Sul (Brazil); Instituto de Ciências Biológicas, Universidade Federal do Rio Grande, Av. Itália km 8, 96203-900, Rio Grande, Rio Grande do Sul (Brazil)

2014-01-01

Silver (Ag), cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) concentrations were analyzed in tissues of juvenile green sea turtles (Chelonia mydas) found stranded along the southern Atlantic coast in Brazil. Green sea turtles were collected (n = 29), measured (curved carapace length: CCL) and had their muscle, liver, and kidney dissected for metal concentration measurements. Sex was identified in 18 individuals (10 females and 8 males) through gonad histology. No gender differences in CCL and tissue metal concentrations were observed. In the muscle, there was a negative correlation between CCL and Cd and Cu concentrations. Metal concentrations were lower in the muscle than in the liver and kidney. Zn concentration in the muscle was the highest of all metals analyzed (16.6 mg/kg). The kidney showed the highest concentrations of Pb, Cd and Zn (5.4, 28.3 and 54.3 mg/kg, respectively), while the liver had the highest values of Ag and Cu (0.8 and 100.9 mg/kg, respectively). Tissue Ag, Zn and Cd concentrations were similar to those found in green sea turtles from other regions while Cu and Pb values were elevated, likely due to the metal-rich water and sediment reported in the collection area. In the liver and kidney, concentrations of non-essential (Ag, Cd and Pb) and essential (Cu or Zn) metals were positively correlated, likely due to an induced metallothionein synthesis to protect tissue against the toxic effect of metals. This is the first study to report and correlate the concentrations of essential and non-essential metals in tissues of green sea turtles in the Brazilian southern Atlantic coast, an important feeding and developing area for this turtle species. - Highlights: •Juvenile female and male green sea turtles have similar concentrations of metals. •Kidney accumulated more Cd, Pb and Zn while liver accumulated more Ag and Cu. •Cu and Pb concentrations are elevated in liver of sea turtles from southern Brazil. •Concentrations of Cd and Cu in

The morphology of saccular otoliths as a tool to identify different mugilid species from the Northeastern Atlantic and Mediterranean Sea

Science.gov (United States)

Callicó Fortunato, Roberta; Benedito Durà, Vicent; Volpedo, Alejandra

2014-06-01

In the Northeastern Atlantic and Mediterranean Sea there are 8 species of the Mugilidae family: Mugil cephalus, Liza aurata, Liza ramada, Oedalechilus labeo, Chelon labrosus, Liza saliens, Liza carinata and Liza haematocheila. The identification of mugilids is very important for local fisheries management and regulations, but it is difficult using gross morphological characters. This work aims to contribute to the identification of mullets present in the Northeastern Atlantic Ocean and Mediterranean Sea using saccular otolith features of each species. Specimens of C. labrosus, L. aurata, L. ramada, L. saliens and M. cephalus were obtained from Delta del Ebro (40°38'N-0°44'E) in artisanal catches. For L. carinata and O. labeo photographs extracted from AFORO online database were used. L. haematocheila was not studied for lack of otolith samples. A general pattern of the saccular otoliths for this family was identified: the shape of the otoliths are rectangular to oblong with irregular margins; they present a heterosulcoid, ostial sulcus acusticus, with an open funnel-like ostium to the anterior margin and a closed, tubular cauda, ending towards the posterior ventral corner, always larger than the ostium. In the present study, the mugilid species could be recognized using their saccular otolith morphology. Here we give the first key to identify Northeastern Atlantic and Mediterranean mullets. The distinctive features between the species were the position and centrality of the sulcus, the curvature of the cauda, the presence of areal depositions and plateaus, and the type of anterior and posterior regions. These features could be used not only to reinforce the identification keys through morphological and meristic characters of the species, but also to identify the species consumed by piscivores, being the otoliths the only identifiable remains of the individuals.

Seasonal variation in biomarkers in blue mussel (Mytilus edulis), Icelandic scallop (Chlamys islandica) and Atlantic cod (Gadus morhua)—Implications for environmental monitoring in the Barents Sea

International Nuclear Information System (INIS)

Nahrgang, J.; Brooks, S.J.; Evenset, A.; Camus, L.; Jonsson, M.; Smith, T.J.; Lukina, J.; Frantzen, M.; Giarratano, E.; Renaud, P.E.

2013-01-01

In the Barents Sea, the limited data on biological relevant indicators and their responses to various anthropogenic stressors have hindered the development of a consistent scientific basis for selecting indicator species and developing practical procedures for environmental monitoring. Accordingly, the main aim of the present study was to develop a common set of baseline values for contaminants and biomarkers in three species, and to identify their strengths and limitations in monitoring of the Barents Sea. Blue mussel (Mytilus edulis), Icelandic scallop (Chlamys islandica) and Atlantic cod (Gadus morhua) were sampled from a north Norwegian fjord in March, June, September and December 2010. Digestive glands from the bivalve species and liver from Atlantic cod were analysed for biomarkers of oxidative stress (catalase [CAT], glutathione peroxidase [GPX], glutathione-S-transferase activities [GST], lipid peroxidation as thiobarbituric reactive substances [TBARS] and total oxyradical scavenging capacity [TOSC]), biotransformation (ethoxyresorufine-O-deethylase activity [EROD]) and general stress (lysosomal membrane stability [LMS]). Concentrations of polycyclic aromatic hydrocarbons (PAHs) and metals in the bivalves and PAH metabolites in fish bile were quantified. Finally, energy reserves (total lipids, proteins and carbohydrates) and electron transport system (ETS) activity in the digestive gland of the bivalves and liver of Atlantic cod provided background information for reproductive cycle and general physiological status of the organisms. Blue mussel and Icelandic scallop showed very similar trends in biological cycle, biomarker expression and seasonality. Biomarker baselines in Atlantic cod showed weaker seasonal variability. However, important biological events may have been undetected due to the large time intervals between sampling occasions. Physiological biomarkers such as energy reserves and ETS activity were recommended as complementary parameters to the

78 FR 52505 - Mid-Atlantic Fishery Management Council; Public Meeting

Science.gov (United States)

2013-08-23

... Mid-Atlantic Fishery Management Council's (MAFMC) Bluefish Monitoring Committee and Summer Flounder...: The Bluefish Monitoring Committee and Summer Flounder, Scup, and Black Sea Bass Monitoring Committee... associated management measures for the bluefish, summer flounder, scup, and black sea bass fisheries. Multi...

Development of temporal trends of radioactivity in benthic organisms and in water from the deep sea (Atlantic)

International Nuclear Information System (INIS)

Kanisch, G.; Kellermann, H.-J.; Vobach, M.; Krueger, A.

2003-01-01

Since 20 years the Federal Research Centre for Fisheries is performing radioecological studies in the deep sea of the Northeast Atlantic, especially in the area north-west of Spain used for dumping of radioactive waste until 1982. Until 1998/2000, in Benthos some decrease was observed for 137 Cs, however, almost not for 238 Pu, 239,240 Pu and 241 Am. In the dumpsite area the ratio 238 Pu/ 239,240 Pu, about 0.072, showed higher values than in comparison sites, about 0,044. Alpha spectrometric measurements of the atom based ratio 240 Pu/ 239 Pu in Benthos, due to slight deviations from the global fallout value of 0.18, indicated a special impact of the ''Nevada Test Site'' fallout. In rat-tailed fish (Macrouridae) from the deep sea 137Cs decreased since 1989 with an effective half-live of 14.5 years, comparable to that of 16.2 years in the surface water. Related to the concentration in the surface water a 137 Cs concentration factor of 83 was obtained. It is concluded that the dominant source for 137 Cs in deep sea fish is the global fallout. For plutonium isotopes measured in sea water samples from the deep the values of 238 Pu/ 239,240 Pu and 238 Pu, being higher for the dumpsite area, were interpreted as impact of leaking radioactive drums. For this leakage acting as a plutonium source a 238 Pu/ 239,240 Pu ratio of 0.17 was estimated. However, the total plutonium inventory in the deep sea thereby increased by only about 20 %. (orig.)

Tracing Atlantic Water Signature in the Arctic Sea Ice Cover East of Svalbard

Directory of Open Access Journals (Sweden)

Vladimir V. Ivanov

2012-01-01

Full Text Available We focus on the Arctic Ocean between Svalbard and Franz Joseph Land in order to elucidate the possible role of Atlantic water (AW inflow in shaping ice conditions. Ice conditions substantially affect the temperature regime of the Spitsbergen archipelago, particularly in winter. We test the hypothesis that intensive vertical mixing at the upper AW boundary releases substantial heat upwards that eventually reaches the under-ice water layer, thinning the ice cover. We examine spatial and temporal variation of ice concentration against time series of wind, air temperature, and AW temperature. Analysis of 1979–2011 ice properties revealed a general tendency of decreasing ice concentration that commenced after the mid-1990s. AW temperature time series in Fram Strait feature a monotonic increase after the mid-1990s, consistent with shrinking ice cover. Ice thins due to increased sensible heat flux from AW; ice erosion from below allows wind and local currents to more effectively break ice. The winter spatial pattern of sea ice concentration is collocated with patterns of surface heat flux anomalies. Winter minimum sea ice thickness occurs in the ice pack interior above the AW path, clearly indicating AW influence on ice thickness. Our study indicates that in the AW inflow region heat flux from the ocean reduces the ice thickness.

A new species of brooding Psolidae (Echinodermata: Holothuroidea) from deep-sea off Argentina, Southwestern Atlantic Ocean

Science.gov (United States)

Martinez, Mariano I.; Penchaszadeh, Pablo E.

2017-12-01

This paper describes a new species of Psolus (Holothuroidea, Echinodermata), P. lawrencei sp. nov., (19 specimens) found in the deep sea (308-1398 m) in the Southwestern Atlantic Ocean (SWAO) (around 38°S-54°W) with brooders (up to 3.15 mm) in the tentacles of females and a penis-like genital papilla on males. The presence of dorsal scales, the concave shape of the ossicles with a bridge, the distribution of podia on the dorsal side and the absence of large and conspicuous oral and anal valves are unique for this species. Furthermore, this is the first species of this genus found outside Antarctica that broods between its tentacles. The paper also reviews the reproductive, brooding development and morphological characteristics of P. lawrencei sp. nov. and compares them with those of several members of the family Psolidae. Finally, a possible connectivity between the deep-sea populations in the SWAO and in Antarctica is considered based on the appearance of a similar reproductive pattern in populations found in both areas, which suggests a past or present connection between these regions.

Deep-sea dives reveal an unexpected hexactinellid sponge garden on the Rio Grande Rise (SW Atlantic). A mimicking habitat?

Science.gov (United States)

Hajdu, Eduardo; Castello-Branco, Cristiana; Lopes, Daniela A.; Sumida, Paulo Yukio Gomes; Perez, Jose Angel Alvarez

2017-12-01

Long overlooked, sponge grounds are now recognised as important habitats which support high biodiversity. Some of these deep-sea sponge aggregations are formed by hexactinellids, in varying densities, which can occur on both soft and hard substrates. Despite their ecological importance as habitat framework building taxa, hexactinellids have been little studied and only 33 species in this Class were reported from the entire South Atlantic until now. Most of this knowledge was gained from studies conducted on the eastern South America continental slope. Here we report a new hexactinellid sponge garden found by the Shinkai 6500 manned submersible on the Rio Grande Rise, a prominent topographic feature of the deep SW Atlantic. This is the first sponge garden worldwide found to be dominated by the stiff, often dichotomously branching, Sarostegia oculata which may occur in densities of over 5 individuals per square meter. This sponge, of uncertain familial allocation, seems to always carry epibiotic zoanthids, thus mimicking the 3D skeletal framework of actual coral gardens

Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the JOHAN HJORT in the North Atlantic Ocean, North Greenland Sea and Norwegian Sea from 1994-10-29 to 1994-11-23 (NODC Accession 0115681)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115681 includes chemical, discrete sample, physical and profile data collected from JOHAN HJORT in the North Atlantic Ocean, North Greenland Sea and...

An assessment of the radiological impact of sea-dumping at the North East Atlantic dump site

International Nuclear Information System (INIS)

Delow, C.E.; Mobbs, S.F.; Hill, M.D.

1985-04-01

This report describes the models and methodology developed for the assessment of the radiological impact of disposal of low and intermediate level waste on the seabed. The development of the waste package model and the combined model of radionuclide dispersion and interactions with sediments in the world's ocean is outlined. This integrated set of models was used for the radiological assessment of sea dumping at the North-East Atlantic site, which formed part of the recent NEA review of the continued suitability of this site. The predicted radiation doses to man are presented, together with the results of the analysis of the sensitivity of the annual individual doses to critical groups to variations in model parameters. (author)

Air-sea dimethylsulfide (DMS) gas transfer in the North Atlantic: evidence for limited interfacial gas exchange at high wind speed

Science.gov (United States)

Bell, T. G.; De Bruyn, W.; Miller, S. D.; Ward, B.; Christensen, K.; Saltzman, E. S.

2013-11-01

Shipboard measurements of eddy covariance dimethylsulfide (DMS) air-sea fluxes and seawater concentration were carried out in the North Atlantic bloom region in June/July 2011. Gas transfer coefficients (k660) show a linear dependence on mean horizontal wind speed at wind speeds up to 11 m s-1. At higher wind speeds the relationship between k660 and wind speed weakens. At high winds, measured DMS fluxes were lower than predicted based on the linear relationship between wind speed and interfacial stress extrapolated from low to intermediate wind speeds. In contrast, the transfer coefficient for sensible heat did not exhibit this effect. The apparent suppression of air-sea gas flux at higher wind speeds appears to be related to sea state, as determined from shipboard wave measurements. These observations are consistent with the idea that long waves suppress near-surface water-side turbulence, and decrease interfacial gas transfer. This effect may be more easily observed for DMS than for less soluble gases, such as CO2, because the air-sea exchange of DMS is controlled by interfacial rather than bubble-mediated gas transfer under high wind speed conditions.

Efficacy of emamectin benzoate against sea lice infestations of Atlantic salmon, Salmo salar L.: evaluation in the absence of an untreated contemporary control.

Science.gov (United States)

Gustafson, L; Ellis, S; Robinson, T; Marenghi, F; Endris, R

2006-10-01

The efficacy of emamectin benzoate (SLICE) against sea lice infestations of Atlantic salmon, Salmo salar L., is typically assessed using untreated fish, or fish treated with alternative therapeutants, as controls. The State of Maine, USA, is currently under active management for the OIE-notifiable pathogen, infectious salmon anaemia virus (ISAV); consequently, neither control group is feasible in this region. Untreated salmon risk extensive damage from the ectoparasites, and threaten to increase vector-borne exposure or susceptibility of farms to ISAV; and the only treatment presently available in Maine is SLICE. However, because sea lice infestations are unlikely to resolve spontaneously, and response to treatment occurs within weeks, use of a pretreatment baseline is a reasonable alternative for confirmatory studies. We evaluated SLICE efficacy on Atlantic salmon farms in Cobscook Bay 2002-2005, in the absence of untreated controls, using pretreatment lice loads as a reference for calculation. Maximum efficacy ranged from 68% to 100% reduction from initial levels. Time-to-maximum efficacy ranged from 1 to 8 weeks after treatment initiation. Efficacy duration, measured between first reduction and first progressive rise in counts, ranged from 4 to 16 weeks.

Marine proxy evidence linking decadal North Pacific and Atlantic climate

Energy Technology Data Exchange (ETDEWEB)

Hetzinger, S. [University of Toronto Mississauga, CPS-Department, Mississauga, ON (Canada); Leibniz Institute of Marine Sciences, IFM-GEOMAR, Kiel (Germany); Halfar, J. [University of Toronto Mississauga, CPS-Department, Mississauga, ON (Canada); Mecking, J.V.; Keenlyside, N.S. [Leibniz Institute of Marine Sciences, IFM-GEOMAR, Kiel (Germany); University of Bergen, Geophysical Institute and Bjerknes Centre for Climate Research, Bergen (Norway); Kronz, A. [University of Goettingen, Geowissenschaftliches Zentrum, Goettingen (Germany); Steneck, R.S. [University of Maine, Darling Marine Center, Walpole, ME (United States); Adey, W.H. [Smithsonian Institution, Department of Botany, Washington, DC (United States); Lebednik, P.A. [ARCADIS U.S. Inc., Walnut Creek, CA (United States)

2012-09-15

Decadal- to multidecadal variability in the extra-tropical North Pacific is evident in 20th century instrumental records and has significant impacts on Northern Hemisphere climate and marine ecosystems. Several studies have discussed a potential linkage between North Pacific and Atlantic climate on various time scales. On decadal time scales no relationship could be confirmed, potentially due to sparse instrumental observations before 1950. Proxy data are limited and no multi-centennial high-resolution marine geochemical proxy records are available from the subarctic North Pacific. Here we present an annually-resolved record (1818-1967) of Mg/Ca variations from a North Pacific/Bering Sea coralline alga that extends our knowledge in this region beyond available data. It shows for the first time a statistically significant link between decadal fluctuations in sea-level pressure in the North Pacific and North Atlantic. The record is a lagged proxy for decadal-scale variations of the Aleutian Low. It is significantly related to regional sea surface temperature and the North Atlantic Oscillation (NAO) index in late boreal winter on these time scales. Our data show that on decadal time scales a weaker Aleutian Low precedes a negative NAO by several years. This atmospheric link can explain the coherence of decadal North Pacific and Atlantic Multidecadal Variability, as suggested by earlier studies using climate models and limited instrumental data. (orig.)

GHRSST Level 2P North Atlantic Regional Bulk Sea Surface Temperature from the Advanced Very High Resolution Radiometer (AVHRR) on the NOAA-18 satellite produced by NEODAAS (GDS version 1)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A Level 2P swath-based Group for High Resolution Sea Surface Temperature (GHRSST) dataset for the North Atlantic area from the Advanced Very High Resolution...

GHRSST Level 2P North Atlantic Regional Bulk Sea Surface Temperature from the Advanced Very High Resolution Radiometer (AVHRR) on the NOAA-19 satellite produced by NEODAAS (GDS version 1)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A Level 2P swath-based Group for High Resolution Sea Surface Temperature (GHRSST) dataset for the North Atlantic area from the Advanced Very High Resolution...

GHRSST Level 2P North Atlantic Regional Bulk Sea Surface Temperature from the Advanced Very High Resolution Radiometer (AVHRR) on the NOAA-17 satellite produced by NEODAAS (GDS version 1)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A Level 2P swath-based Group for High Resolution Sea Surface Temperature (GHRSST) dataset for the North Atlantic area from the Advanced Very High Resolution...

Linear and non-linear sea-level variations in the Adriatic Sea from tide gauge records (1872-2012

Directory of Open Access Journals (Sweden)

Gaia Galassi

2015-03-01

Full Text Available We have analyzed tide gauge data from the Adriatic Sea in order to assess the secular sea-level trend, its acceleration and the existence of possible cyclic variation. Analyzing the sea-level stack of all Adriatic tide gauges, we have obtained a trend of (1.25±0.04 mm yr-1, in agreement with that observed for the last century in the Mediterranean Sea, and an acceleration that is negligibile compared to the average global values. By means of the Ensemble Empirical Mode Decomposition technique, we have evidenced an energetic oscillation with a period of ∼20 years that we relate with the recurrence of opposite phases in the Atlantic Multi–decadal Oscillation and North Atlantic Oscillation indices. We suggest that anomalously high sea-level values observed at all the Adriatic tide gauges during 2010 and 2011 can be explained by the rising phase of this 20 years cycle.

Climate impacts of parameterized Nordic Sea overflows

Science.gov (United States)

Danabasoglu, Gokhan; Large, William G.; Briegleb, Bruce P.

2010-11-01

A new overflow parameterization (OFP) of density-driven flows through ocean ridges via narrow, unresolved channels has been developed and implemented in the ocean component of the Community Climate System Model version 4. It represents exchanges from the Nordic Seas and the Antarctic shelves, associated entrainment, and subsequent injection of overflow product waters into the abyssal basins. We investigate the effects of the parameterized Denmark Strait (DS) and Faroe Bank Channel (FBC) overflows on the ocean circulation, showing their impacts on the Atlantic Meridional Overturning Circulation and the North Atlantic climate. The OFP is based on the Marginal Sea Boundary Condition scheme of Price and Yang (1998), but there are significant differences that are described in detail. Two uncoupled (ocean-only) and two fully coupled simulations are analyzed. Each pair consists of one case with the OFP and a control case without this parameterization. In both uncoupled and coupled experiments, the parameterized DS and FBC source volume transports are within the range of observed estimates. The entrainment volume transports remain lower than observational estimates, leading to lower than observed product volume transports. Due to low entrainment, the product and source water properties are too similar. The DS and FBC overflow temperature and salinity properties are in better agreement with observations in the uncoupled case than in the coupled simulation, likely reflecting surface flux differences. The most significant impact of the OFP is the improved North Atlantic Deep Water penetration depth, leading to a much better comparison with the observational data and significantly reducing the chronic, shallow penetration depth bias in level coordinate models. This improvement is due to the deeper penetration of the southward flowing Deep Western Boundary Current. In comparison with control experiments without the OFP, the abyssal ventilation rates increase in the North

Simulating the Regional Impact of Dust on the Middle East Climate and the Red Sea

KAUST Repository

Osipov, Sergey

2018-01-19

The Red Sea is located between North Africa and the Arabian Peninsula, the largest sources of dust in the world. Satellite retrievals show very high aerosol optical depth in the region, which increases during the summer season, especially over the southern Red Sea. Previously estimated and validated radiative effect from dust is expected to have a profound thermal and dynamic impact on the Red Sea, but that impact has not yet been studied or evaluated. Due to the strong dust radiative effect at the sea surface, uncoupled ocean modeling approaches with prescribed atmospheric boundary conditions result in an unrealistic ocean response. Therefore, to study the impact of dust on the regional climate of the Middle East and the Red Sea, we employed the Regional Ocean Modeling System fully coupled with the Weather Research and Forecasting model. We modified the atmospheric model to account for the radiative effect of dust. The simulations show that, in the equilibrium response, dust cools the Red Sea, reduces the surface wind speed, and weakens both the exchange at the Bab-el-Mandeb strait and the overturning circulation. The salinity distribution, freshwater, and heat budgets are significantly altered. A validation of the simulations against satellite products indicates that accounting for radiative effect from dust almost completely removes the bias and reduces errors in the top of the atmosphere fluxes and sea surface temperature. Our results suggest that dust plays an important role in the energy balance, thermal, and circulation regimes in the Red Sea.

Simulating the Regional Impact of Dust on the Middle East Climate and the Red Sea

Science.gov (United States)

Osipov, Sergey; Stenchikov, Georgiy

2018-02-01

The Red Sea is located between North Africa and the Arabian Peninsula, the largest sources of dust in the world. Satellite retrievals show very high aerosol optical depth in the region, which increases during the summer season, especially over the southern Red Sea. Previously estimated and validated radiative effect from dust is expected to have a profound thermal and dynamic impact on the Red Sea, but that impact has not yet been studied or evaluated. Due to the strong dust radiative effect at the sea surface, uncoupled ocean modeling approaches with prescribed atmospheric boundary conditions result in an unrealistic ocean response. Therefore, to study the impact of dust on the regional climate of the Middle East and the Red Sea, we employed the Regional Ocean Modeling System fully coupled with the Weather Research and Forecasting model. We modified the atmospheric model to account for the radiative effect of dust. The simulations show that, in the equilibrium response, dust cools the Red Sea, reduces the surface wind speed, and weakens both the exchange at the Bab-el-Mandeb strait and the overturning circulation. The salinity distribution, freshwater, and heat budgets are significantly altered. A validation of the simulations against satellite products indicates that accounting for radiative effect from dust almost completely removes the bias and reduces errors in the top of the atmosphere fluxes and sea surface temperature. Our results suggest that dust plays an important role in the energy balance, thermal, and circulation regimes in the Red Sea.

Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from HUDSON in the North Atlantic Ocean, North Greenland Sea and Norwegian Sea from 1982-02-28 to 1982-04-04 (NODC Accession 0113889)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0113889 includes chemical, discrete sample, physical and profile data collected from HUDSON in the North Atlantic Ocean, North Greenland Sea and...

75 FR 61094 - Drawbridge Operation Regulation; Atlantic Intracoastal Waterway, Beaufort, SC

Science.gov (United States)

2010-10-04

.... Highway 21, Sea Island Parkway Bridge at mile marker 536 over the Beaufort River (Atlantic Intracoastal... Bridge, which is across the Atlantic Intracoastal Waterway at mile 539.0 in Port Royal, South Carolina... Bridge, across the Beaufort River, Mile 536.0 at Beaufort. The draw shall operate as follows: (1) On...

Temperature profile and water depth data from BT and XBT casts in the Atlantic Ocean from USCGC POLAR SEA from 14 December 1983 to 06 May 1984 (NODC Accession 8600108)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and water depth data were collected using BT and XBT casts from the USCGC POLAR SEA in the Atlantic Ocean. Data were collected from 14 December...

The Effect of Seasonal Variability of Atlantic Water on the Arctic Sea Ice Cover

Science.gov (United States)

Ivanov, V. V.; Repina, I. A.

2018-01-01

Under the influence of global warming, the sea ice in the Arctic Ocean (AO) is expected to reduce with a transition toward a seasonal ice cover by the end of this century. A comparison of climate-model predictions with measurements shows that the actual rate of ice cover decay in the AO is higher than the predicted one. This paper argues that the rapid shrinking of the Arctic summer ice cover is due to its increased seasonality, while seasonal oscillations of the Atlantic origin water temperature create favorable conditions for the formation of negative anomalies in the ice-cover area in winter. The basis for this hypothesis is the fundamental possibility of the activation of positive feedback provided by a specific feature of the seasonal cycle of the inflowing Atlantic origin water and the peaking of temperature in the Nansen Basin in midwinter. The recently accelerated reduction in the summer ice cover in the AO leads to an increased accumulation of heat in the upper ocean layer during the summer season. The extra heat content of the upper ocean layer favors prerequisite conditions for winter thermohaline convection and the transfer of heat from the Atlantic water (AW) layer to the ice cover. This, in turn, contributes to further ice thinning and a decrease in ice concentration, accelerated melting in summer, and a greater accumulation of heat in the ocean by the end of the following summer. An important role is played by the seasonal variability of the temperature of AW, which forms on the border between the North European and Arctic basins. The phase of seasonal oscillation changes while the AW is moving through the Nansen Basin. As a result, the timing of temperature peak shifts from summer to winter, additionally contributing to enhanced ice melting in winter. The formulated theoretical concept is substantiated by a simplified mathematical model and comparison with observations.

An overview of chemosynthetic symbioses in bivalves from the North Atlantic and Mediterranean Sea

Science.gov (United States)

Duperron, S.; Gaudron, S. M.; Rodrigues, C. F.; Cunha, M. R.; Decker, C.; Olu, K.

2013-05-01

Deep-sea bivalves found at hydrothermal vents, cold seeps and organic falls are sustained by chemosynthetic bacteria that ensure part or all of their carbon nutrition. These symbioses are of prime importance for the functioning of the ecosystems. Similar symbioses occur in other bivalve species living in shallow and coastal reduced habitats worldwide. In recent years, several deep-sea species have been investigated from continental margins around Europe, West Africa, eastern Americas, the Gulf of Mexico, and from hydrothermal vents on the Mid-Atlantic Ridge. In parallel, numerous, more easily accessible shallow marine species have been studied. Herein we provide a summary of the current knowledge available on chemosymbiotic bivalves in the area ranging west-to-east from the Gulf of Mexico to the Sea of Marmara, and north-to-south from the Arctic to the Gulf of Guinea. Characteristics of symbioses in 53 species from the area are summarized for each of the five bivalve families documented to harbor chemosynthetic symbionts (Mytilidae, Vesicomyidae, Solemyidae, Thyasiridae and Lucinidae). Comparisons are made between the families, with special emphasis on ecology, life cycle, and connectivity. Chemosynthetic symbioses are a major adaptation to ecosystems and habitats exposed to reducing conditions. However, relatively little is known regarding their diversity and functioning, apart from a few "model species" on which effort has focused over the last 30 yr. In the context of increasing concern about biodiversity and ecosystems, and increasing anthropogenic pressure on oceans, we advocate a better assessment of the diversity of bivalve symbioses in order to evaluate the capacities of these remarkable ecological and evolutionary units to withstand environmental change.

An overview of chemosynthetic symbioses in bivalves from the North Atlantic and Mediterranean Sea

Directory of Open Access Journals (Sweden)

S. Duperron

2013-05-01

Full Text Available Deep-sea bivalves found at hydrothermal vents, cold seeps and organic falls are sustained by chemosynthetic bacteria that ensure part or all of their carbon nutrition. These symbioses are of prime importance for the functioning of the ecosystems. Similar symbioses occur in other bivalve species living in shallow and coastal reduced habitats worldwide. In recent years, several deep-sea species have been investigated from continental margins around Europe, West Africa, eastern Americas, the Gulf of Mexico, and from hydrothermal vents on the Mid-Atlantic Ridge. In parallel, numerous, more easily accessible shallow marine species have been studied. Herein we provide a summary of the current knowledge available on chemosymbiotic bivalves in the area ranging west-to-east from the Gulf of Mexico to the Sea of Marmara, and north-to-south from the Arctic to the Gulf of Guinea. Characteristics of symbioses in 53 species from the area are summarized for each of the five bivalve families documented to harbor chemosynthetic symbionts (Mytilidae, Vesicomyidae, Solemyidae, Thyasiridae and Lucinidae. Comparisons are made between the families, with special emphasis on ecology, life cycle, and connectivity. Chemosynthetic symbioses are a major adaptation to ecosystems and habitats exposed to reducing conditions. However, relatively little is known regarding their diversity and functioning, apart from a few "model species" on which effort has focused over the last 30 yr. In the context of increasing concern about biodiversity and ecosystems, and increasing anthropogenic pressure on oceans, we advocate a better assessment of the diversity of bivalve symbioses in order to evaluate the capacities of these remarkable ecological and evolutionary units to withstand environmental change.

Loss of sea ice during winter north of Svalbard

Directory of Open Access Journals (Sweden)

Ingrid H. Onarheim

2014-06-01

Full Text Available Sea ice loss in the Arctic Ocean has up to now been strongest during summer. In contrast, the sea ice concentration north of Svalbard has experienced a larger decline during winter since 1979. The trend in winter ice area loss is close to 10% per decade, and concurrent with a 0.3°C per decade warming of the Atlantic Water entering the Arctic Ocean in this region. Simultaneously, there has been a 2°C per decade warming of winter mean surface air temperature north of Svalbard, which is 20–45% higher than observations on the west coast. Generally, the ice edge north of Svalbard has retreated towards the northeast, along the Atlantic Water pathway. By making reasonable assumptions about the Atlantic Water volume and associated heat transport, we show that the extra oceanic heat brought into the region is likely to have caused the sea ice loss. The reduced sea ice cover leads to more oceanic heat transferred to the atmosphere, suggesting that part of the atmospheric warming is driven by larger open water area. In contrast to significant trends in sea ice concentration, Atlantic Water temperature and air temperature, there is no significant temporal trend in the local winds. Thus, winds have not caused the long-term warming or sea ice loss. However, the dominant winds transport sea ice from the Arctic Ocean into the region north of Svalbard, and the local wind has influence on the year-to-year variability of the ice concentration, which correlates with surface air temperatures, ocean temperatures, as well as the local wind.

Obliquity-driven expansion of North Atlantic sea ice controls structure of the last glacial

Science.gov (United States)

Turney, Chris; Thomas, Zoe; Hutchinson, David; Bradshaw, Corey; Brook, Barry; England, Matthew; Fogwill, Christopher; Jones, Richard; Palmer, Jonathan; Hughen, Konrad; Cooper, Alan

2015-04-01

North Atlantic late-Pleistocene climate was characterised by a series of abrupt climate changes, the most extreme of which were the Dansgaard-Oeschger (D-O) events; millennial-scale oscillations that switched rapidly between cold and warm atmospheric conditions of up to Δ16°C, most strongly expressed during the period 60-30 ka. Time series analysis of palaeoclimate ice core records is one of the best ways to detect threshold behaviour in the climate system; however, some of these techniques can be age model dependent. Spectral analysis of a new Greenland-Cariaco GICC05 age model (GICC05-CB), generated by combining the GICC05 and Cariaco ∂18O chronologies, reveals a change in the dominant periodicities at ~31 ka, consistent with the cessation of the D-O events. While the GICC05-CB has the same ∂18O structure as GICC05, the different periodicity profile reveals a change in the climate system at 31 ka. Stability analysis of the ∂18O time series over the last 60 ka determines the number of states the climate experienced over time, and reveals a bifurcation in the climate system at 31 ka, switching from a bistable to a monostable state. Early warning signals of this bifurcation are also detected starting 10,000 years before the shift in the form of increasing autocorrelation and variance. This is consistent with the climate system experiencing a slow forcing towards a critical threshold. These signals are found in both the GICC05-CB and GICC05 chronologies, though the timing of the bifurcation point varies slightly. We suggest that this bifurcation is linked to a minima in obliquity, causing greatly expanded sea ice in the Labrador sea. Modelling runs from the CSIRO Mk3L Earth-system model indicates that extensive sea ice cover is established in the Labrador Sea and North Pacific at the obliquity minima centred on 28.5 ka. This expanded sea ice is thus responsible for shifting the Northern Hemisphere westerlies southwards and reducing the strength of the AMOC

78 FR 57620 - Mid-Atlantic Fishery Management Council (MAFMC); Public Meetings

Science.gov (United States)

2013-09-19

... sea bass, and bluefish management measures for 2014-15 (2014 for Bluefish) in conjunction with the Atlantic States Marine Fisheries Commission's (ASMFC) Summer Flounder, Scup, Black Sea Bass, and Bluefish... Bluefish Board will review the Scientific and Statistical Committee (SSC), the associated Monitoring...

First satellite tracks of neonate sea turtles redefine the ‘lost years’ oceanic niche

Science.gov (United States)

Mansfield, Katherine L.; Wyneken, Jeanette; Porter, Warren P.; Luo, Jiangang

2014-01-01

Few at-sea behavioural data exist for oceanic-stage neonate sea turtles, a life-stage commonly referred to as the sea turtle ‘lost years’. Historically, the long-term tracking of small, fast-growing organisms in the open ocean was logistically or technologically impossible. Here, we provide the first long-term satellite tracks of neonate sea turtles. Loggerheads (Caretta caretta) were remotely tracked in the Atlantic Ocean using small solar-powered satellite transmitters. We show that oceanic-stage turtles (i) rarely travel in Continental Shelf waters, (ii) frequently depart the currents associated with the North Atlantic Subtropical Gyre, (iii) travel quickly when in Gyre currents, and (iv) select sea surface habitats that are likely to provide a thermal benefit or refuge to young sea turtles, supporting growth, foraging and survival. Our satellite tracks help define Atlantic loggerhead nursery grounds and early loggerhead habitat use, allowing us to re-examine sea turtle ‘lost years’ paradigms. PMID:24598420

State and local governments plan for development of most land vulnerable to rising sea level along the US Atlantic coast

International Nuclear Information System (INIS)

Titus, J G; Hudgens, D E; Kassakian, J M; Trescott, D L; Craghan, M; Nuckols, W H; Hershner, C H; Linn, C J; Merritt, P G; McCue, T M; O'Connell, J F; Tanski, J; Wang, J

2009-01-01

Rising sea level threatens existing coastal wetlands. Overall ecosystems could often survive by migrating inland, if adjacent lands remained vacant. On the basis of 131 state and local land use plans, we estimate that almost 60% of the land below 1 m along the US Atlantic coast is expected to be developed and thus unavailable for the inland migration of wetlands. Less than 10% of the land below 1 m has been set aside for conservation. Environmental regulators routinely grant permits for shore protection structures (which block wetland migration) on the basis of a federal finding that these structures have no cumulative environmental impact. Our results suggest that shore protection does have a cumulative impact. If sea level rise is taken into account, wetland policies that previously seemed to comply with federal law probably violate the Clean Water Act.

Review of middle eastern hydro climatology and seasonal tele connections

International Nuclear Information System (INIS)

Pagano, T. C.; Mahani, S.; Nazemosadat, M. J.; Sorooshian, S.

2003-01-01

International hydro climatic variability in the Middle East is explored. A review is done on studies linking local climate with large-scale tele connections. These studies suggest that El Nino has a weak tendency of bringing better than normal conditions to the region during fall / winter. This signal is unstable in time and has considerable decadal variability. No consensus exists on the general start and end dates of various climate epochs, nor is there an explanation of the physical causes of the decad al variability, suggesting that the inter annual signal of El Nino in the Middle East may be transient and difficult to predict. In contrast, the influence of the North Atlantic Oscillation on temperature, precipitation and strea flow is strong, with high North Atlantic Oscillation winters favoring dry and cool conditions in the region. Recommendations are made on how to improve the ability to understand and forecast Middle Eastern inter annual variability, namely, 1) improve access to instrumental data, 2) coordinate research, forecasts and user involvement through a regional forum and 3) further explore the impacts of North Atlantic Oscillation in the Middle East

Astronomical calibration of the geological timescale: closing the middle Eocene gap

Science.gov (United States)

Westerhold, T.; Röhl, U.; Frederichs, T.; Bohaty, S. M.; Zachos, J. C.

2015-09-01

To explore cause and consequences of past climate change, very accurate age models such as those provided by the astronomical timescale (ATS) are needed. Beyond 40 million years the accuracy of the ATS critically depends on the correctness of orbital models and radioisotopic dating techniques. Discrepancies in the age dating of sedimentary successions and the lack of suitable records spanning the middle Eocene have prevented development of a continuous astronomically calibrated geological timescale for the entire Cenozoic Era. We now solve this problem by constructing an independent astrochronological stratigraphy based on Earth's stable 405 kyr eccentricity cycle between 41 and 48 million years ago (Ma) with new data from deep-sea sedimentary sequences in the South Atlantic Ocean. This new link completes the Paleogene astronomical timescale and confirms the intercalibration of radioisotopic and astronomical dating methods back through the Paleocene-Eocene Thermal Maximum (PETM, 55.930 Ma) and the Cretaceous-Paleogene boundary (66.022 Ma). Coupling of the Paleogene 405 kyr cyclostratigraphic frameworks across the middle Eocene further paves the way for extending the ATS into the Mesozoic.

North Atlantic deep water formation and AMOC in CMIP5 models

Directory of Open Access Journals (Sweden)

C. Heuzé

2017-07-01

Full Text Available Deep water formation in climate models is indicative of their ability to simulate future ocean circulation, carbon and heat uptake, and sea level rise. Present-day temperature, salinity, sea ice concentration and ocean transport in the North Atlantic subpolar gyre and Nordic Seas from 23 CMIP5 (Climate Model Intercomparison Project, phase 5 models are compared with observations to assess the biases, causes and consequences of North Atlantic deep convection in models. The majority of models convect too deep, over too large an area, too often and too far south. Deep convection occurs at the sea ice edge and is most realistic in models with accurate sea ice extent, mostly those using the CICE model. Half of the models convect in response to local cooling or salinification of the surface waters; only a third have a dynamic relationship between freshwater coming from the Arctic and deep convection. The models with the most intense deep convection have the warmest deep waters, due to a redistribution of heat through the water column. For the majority of models, the variability of the Atlantic Meridional Overturning Circulation (AMOC is explained by the volumes of deep water produced in the subpolar gyre and Nordic Seas up to 2 years before. In turn, models with the strongest AMOC have the largest heat export to the Arctic. Understanding the dynamical drivers of deep convection and AMOC in models is hence key to realistically forecasting Arctic oceanic warming and its consequences for the global ocean circulation, cryosphere and marine life.

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

Science.gov (United States)

Darroch, Louise; Buck, Justin

2017-04-01

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

Spawning of bluefin tuna in the black sea: historical evidence, environmental constraints and population plasticity

DEFF Research Database (Denmark)

Mackenzie, Brian R; Mariani, Patrizio

2012-01-01

The lucrative and highly migratory Atlantic bluefin tuna, Thunnus thynnus (Linnaeus 1758; Scombridae), used to be distributed widely throughout the north Atlantic Ocean, Mediterranean Sea and Black Sea. Its migrations have supported sustainable fisheries and impacted local cultures since antiquity...

Reconstruction of middle-west Pangaea in and around Mediterranean Sea : A proposal of Pangaea model A3

Science.gov (United States)

Kwon, O.-hyeok; Cheong, Hyeong-Bin

2017-04-01

, which looks better than that presented by Bullard who succeeded in fitting almost seamlessly the west and east coastal lines of the Atlantic ocean. Such an elaborate fit was also done for most of middle-west part of Pangaea including Mediterranean Sea. Secondly, the Pangaea A3 appeared to be in strong support of the paleomagnetism observation. Though not perfect agreement with the paleomagnetism, the present model seems to be in better agreement than any other previous models. Thirdly, the Pangaea A3 model has brought a settlement to several unsolved problems such as overlapping of north- and south- America continent and the Europe and northern edge of the Africa. Fourthly, the Pangaea A3 model is also in good agreement with the paleo-geological survey, because it shows almost perfect match in the climate, biological distribution, and position of glaciers at those times. Fifthly, the Pangaea model clearly explains why the gap between the Gondwana and Laurasia becomes broader toward the east. Lastly, the present study was performed using an elaborate software, G-plate, to produce accurate and reliable results.

Holocene climate and fjord glaciations in Northeast Greenland: implications for IRD deposition in the North Atlantic

DEFF Research Database (Denmark)

Reeh, Niels

2004-01-01

been released by intensive sub-glacial melting during the long stay of the ice-islands in coastal waters. The Holocene glacial geological record from Northeast Greenland is compared to the record of ice rafted debris (IRD) from North Atlantic deep-sea sediment cores. The comparison shows that transport...... by icebergs in the form of basal debris is unlikely to be the dominant transport mechanism of IRD to deposition sites in the North Atlantic during the Holocene. The ice rafted debris is more likely to be carried at the surface of sea- (or glacier) ice. This supports the result of previous studies by other...... workers that changes of atmospheric and ocean-surface circulation and temperature are the likely causes of Holocene cycles in IRD concentration in North Atlantic deep-sea sediments....

Source of Aegean Sea harbour porpoises

DEFF Research Database (Denmark)

Lockyer, Christina; Rosel, P. E.; Frantzis, A.

2003-01-01

Documented sightings of harbour porpoises in the Mediterranean are rare, although the species is common in the neighbouring North Atlantic and Black Sea. However, in the past 2 decades, 4 harbour porpoises Phocoena phocoena have been recorded in the northern Aegean Sea in the eastern Mediterranea...

Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the HAKON MOSBY in the North Atlantic Ocean, North Greenland Sea and Norwegian Sea from 2001-05-27 to 2001-06-19 (NODC Accession 0113754)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113754 includes chemical, discrete sample, physical and profile data collected from HAKON MOSBY in the North Atlantic Ocean, North Greenland Sea and...

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.

Tropical Atlantic-Korea teleconnection pattern during boreal summer season

Science.gov (United States)

Ham, Yoo-Geun; Chikamoto, Yoshimitsu; Kug, Jong-Seong; Kimoto, Masahide; Mochizuki, Takashi

2017-10-01

The remote impact of tropical Atlantic sea surface temperature (SST) variability on Korean summer precipitation is examined based on observational data analysis along with the idealized and hindcast model experiments. Observations show a significant correlation (i.e. 0.64) between Korean precipitation anomalies (averaged over 120-130°E, 35-40°N) and the tropical Atlantic SST index (averaged over 60°W-20°E, 30°S-30°N) during the June-July-August (JJA) season for the 1979-2010 period. Our observational analysis and partial-data assimilation experiments using the coupled general circulation model demonstrate that tropical Atlantic SST warming induces the equatorial low-level easterly over the western Pacific through a reorganization of the global Walker Circulation, causing a decreased precipitation over the off-equatorial western Pacific. As a Gill-type response to this diabatic forcing, an anomalous low-level anticyclonic circulation appears over the Philippine Sea, which transports wet air from the tropics to East Asia through low-level southerly, resulting an enhanced precipitation in the Korean peninsula. Multi-model hindcast experiments also show that predictive skills of Korean summer precipitation are improved by utilizing predictions of tropical Atlantic SST anomalies as a predictor for Korean precipitation anomalies.

Cloud amount/frequency, NITRATE and other data from POISK, FRITJOF NANSEN and other platforms in the NE Atlantic and Norwegian Sea from 1969-04-17 to 1980-09-28 (NODC Accession 9000077)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Russian Ocean Station data was collected in Norwegian Sea and NE Atlantic (limit-40 W) using four different Ships by Polar Research and Designing Institute of...

Paleoceanographic records in the sedimentary cores from the middle Okinawa Trough

Institute of Scientific and Technical Information of China (English)

无

2003-01-01

Two gravity piston cores (Cores 155 and 180) involved in this study were collected from the middle Okinawa Trough. Stratigraphy of the two cores was divided and classified based on the features of planktonic foraminifera oxygen isotope changes together with depositional sequence, millennium-scale climatic event comparison, carbonate cycles and AMS14C dating. Some paleoclimatic information contained in sediments of these cores was extracted to discuss the paleoclimatic change rules and the short-time scale events presented in interglacial period. Analysis on the variation of oxygen isotope values in stage two shows that the middle part of the Okinawa Trough may have been affected by fresh water from the Yellow River and the Yangtze River during the Last Glacial Maximum (LGM). The oxygen isotope value oscillating ranges of the cores have verified that the marginal sea has an amplifying effect on climate changes. The Δ13c of benthic foraminifera Uvigerina was lighter in the glacial period than that in the interglacial period, which indicates that the Paleo-Kuroshio's main stream moved eastward and its influence area decreased. According to the temperature difference during the "YD" period existing in Core 180 and other data, we can reach the conclusion that the climatic changes in the middle Okinawa Trough area were controlled by global climatic changes, but some regional factors had also considerable influence on the climate changes. Some results in this paper support Fairbanks's point that the "YD" event was a brief stagnation of sea level rising during the global warming up procession. Moreover, the falling of sea level in the glacial period weakened the exchange between the bottom water of the Okinawa Trough and the deep water of the northwestern Pacific Ocean and resulted in low oxygen state of bottom water in this area. These procedures are the reasons for carbonate cycle in the Okinawa Trough area being consistent with the "Atlantic type " carbonate cycle.

Paleoceanographic records in the sedimentary cores from the middle Okinawa Trough

Institute of Scientific and Technical Information of China (English)

LIUYanguang; FUYunxia; DUDewen; MENGXianwei; LIANGRuicai; LITiegang; WUShiying

2003-01-01

Two gravity piston cores (Cores 155 and 180) involved in this study were collected from the middle Okinawa Trough. Stratigraphy of the two cores was divided and classified based on the features of planktonic foraminifera oxygen isotope changes together with depositional sequence,millennium-scale climatic event comparison, carbonate cycles and AMS14C dating. Some paleoclimatic information contained in sediments of these cores was extracted to discuss the paleoclimatic change rules and the short-time scale events presented in interglacial period. Analysis on the variation of oxygen isotope values in stage two shows that the middle part of the Okinawa Trough may have been affected by fresh water from the Yellow River and the Yangtze River during the Last Glacial Maximum (LGM). The oxygen isotope value oscillating ranges of the cores have verified that the marginal sea has an amplifying effect on climate changes.The δ13C of benthic foraminifera Uvigerina was lighter in the glacial period than that in the interglacial period, which indicates that the Paleo-Kuroshio's main stream moved eastward and its influence area decreased. According to the temperature difference during the “YD” period existing in Core 180 and other data, we can reach the conclusion that the climatic changes in the middle Okinawa Trough area were controlled by global climatic changes, but some regional factors had also considerable influence on the climatechanges. Some results in this paper support Fairbanks's point that the “YD” event was a brief stagnation of sea level rising during the global warming up procession. Moreover,the falling of sea level in the glacial period weakened the exchange between the bottom water of the Okinawa Trough and the deep water of the northwestern Pacific Ocean and resulted in low oxygen state of bottom water in this area.These procedures are the reasons for carbonate cycle in the Okinawa Trough area being consistent with the “Atlantic type”carbonate cycle.

Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the G.O. SARS in the North Atlantic Ocean, North Greenland Sea and Norwegian Sea from 2003-09-22 to 2003-10-13 (NODC Accession 0113752)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113752 includes chemical, discrete sample, physical and profile data collected from G.O. SARS in the North Atlantic Ocean, North Greenland Sea and...

The role of the Strait of Gibraltar in shaping the genetic structure of the Mediterranean Grenadier, Coryphaenoides mediterraneus, between the Atlantic and Mediterranean Sea.

Directory of Open Access Journals (Sweden)

Diana Catarino

Full Text Available Population genetic studies of species inhabiting the deepest parts of the oceans are still scarce and only until recently we started to understand how oceanographic processes and topography affect dispersal and gene flow patterns. The aim of this study was to investigate the spatial population genetic structure of the bathyal bony fish Coryphaenoides mediterraneus, with a focus on the Atlantic-Mediterranean transition. We used nine nuclear microsatellites and the mitochondrial cytochrome c oxidase I gene from 6 different sampling areas. No population genetic structure was found within Mediterranean with both marker types (mean ΦST = 0.0960, FST = -0.0003, for both P > 0.05. However, within the Atlantic a contrasting pattern of genetic structure was found for the mtDNA and nuclear markers (mean ΦST = 0.2479, P 0.05. When comparing samples from Atlantic and Mediterranean they exhibited high and significant levels of genetic divergence (mean ΦST = 0.7171, FST = 0.0245, for both P < 0.001 regardless the genetic marker used. Furthermore, no shared haplotypes were found between Atlantic and Mediterranean populations. These results suggest very limited genetic exchange between Atlantic and Mediterranean populations of C. mediterraneus, likely due to the shallow bathymetry of the Strait of Gibraltar acting as a barrier to gene flow. This physical barrier not only prevents the direct interactions between the deep-living adults, but also must prevent interchange of pelagic early life stages between the two basins. According to Bayesian simulations it is likely that Atlantic and Mediterranean populations of C. mediterraneus were separated during the late Pleistocene, which is congruent with results for other deep-sea fish from the same region.

Are Calanus spp. shifting poleward in the North Atlantic? A habitat modelling approach

KAUST Repository

Chust, Guillem

2013-09-16

In the last decade, the analysis based on Continuous Plankton Recorder survey in the eastern North Atlantic Ocean detected one of the most striking examples of marine poleward migration related to sea warming. The main objective of this study is to verify the poleward shift of zooplankton species (Calanus finmarchicus, C. glacialis, C. helgolandicus, C. hyperboreus) for which distributional changes have been recorded in the North Atlantic Ocean and to assess how much of this shift was triggered by sea warming, using Generalized Additive Models. To this end, the population gravity centre of observed data was compared with that of a series of simulation experiments: (i) a model using only climate factors (i.e. niche-based model) to simulate species habitat suitability, (ii) a model using only temporal and spatial terms to reconstruct the population distribution, and (iii) a model using both factors combined, using a subset of observations as independent dataset for validation. Our findings show that only C. finmarchicus had a consistent poleward shift, triggered by sea warming, estimated in 8.1 km per decade in the North Atlantic (16.5 per decade for the northeast), which is substantially lower than previous works at the assemblage level and restricted to the Northeast Atlantic. On the contrary, C. helgolandicus is expanding in all directions, although its northern distribution limit in the North Sea has shifted northward. Calanus glacialis and C. hyperboreus, which have the geographic centres of populations mainly in the NW Atlantic, showed a slight southward shift, probably responding to cool water penetrating southward in the Labrador Current. Our approach, supported by high model accuracy, shows its power in detecting species latitudinal shifts and identifying its causes, since the trend of occurrence observed data is influenced by the sampling frequency, which has progressively concentrated to lower latitudes with time. © 2013 © 2013 International Council for

CARINA TCO2 data in the Atlantic Ocean

Directory of Open Access Journals (Sweden)

R. Wanninkhof

2010-07-01

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

Noise induced multidecadal variability in the North Atlantic: excitation of normal modes

NARCIS (Netherlands)

Frankcombe, L.M.; Dijkstra, H.A.; von der Heydt, A.S.

2009-01-01

In this paper it is proposed that the stochastic excitation of a multidecadal internal ocean mode is at the origin of the multidecadal sea surface temperature variability in the North Atlantic. The excitation processes of the spatial sea surface temperature pattern associated with this multidecadal

The relation between AMOC, gyre circulation, and meridional heat transports in the North Atlantic in model simulations of the last millennium

Science.gov (United States)

Jungclaus, Johann; Moreno-Chamarro, Eduardo; Lohmann, Katja

2016-04-01

While it is clear that the Atlantic Meridional Overturning Circulation (AMOC) is responsible for meridional heat transfer from the South Atlantic and the tropics to the North Atlantic, the majority of the heat transport in the northern North Atlantic and the Nordic seas is carried by the gyre system. However, the detailed mechanisms determining the interaction between and the temporal modulation of the components of the northward heat transport system are not clear. Long-term climate records and model simulations can help to identify important processes and to provide background for the changes that are presently observed. Multi-centennial proxy records from the subpolar North Atlantic and the Nordic Seas indicate, for example, an out-of-phase behavior of sea surface temperature and gyre circulation between the two regions with consequences for regional climate. Paleoceanographic evidence from Fram Strait shows a pronounced modulation of heat transfer to the Arctic by the Atlantic Water layer during the last 2000 years and reconstructions from the Subpolar North Atlantic suggest a role of ocean circulation in the transition between the Medieval Climate Anomaly and the Little Ice Age. Here we explore a small ensemble of last millennium simulations, carried out with the Max Planck Institute Earth System Model, and analyze mechanisms connecting the AMOC and gyre circulation and their relation to external forcing. Our results support the important role of the Subpolar Gyre strength and the related meridional mass and temperature fluxes. We find that the modulation of the northward heat transport into the Nordic Seas and the Arctic has pronounced impact on sea-ice distribution, ocean-atmosphere interaction, and the surface climate in Scandinavia and Western Europe.

Interannual rainfall variability in the Amazon basin and sea-surface temperatures in the equatorial Pacific and the tropical Atlantic Oceans

Science.gov (United States)

Ronchail, Josyane; Cochonneau, Gérard; Molinier, Michel; Guyot, Jean-Loup; Chaves, Adriana Goretti De Miranda; Guimarães, Valdemar; de Oliveira, Eurides

2002-11-01

Rainfall variability in the Amazon basin is studied in relation to sea-surface temperatures (SSTs) in the equatorial Pacific and the northern and southern tropical Atlantic during the 1977-99 period, using the HiBAm original rainfall data set and complementary cluster and composite analyses.The northeastern part of the basin, north of 5 °S and east of 60 °W, is significantly related with tropical SSTs: a rainier wet season is observed when the equatorial Pacific and the northern (southern) tropical Atlantic are anomalously cold (warm). A shorter and drier wet season is observed during El Niño events and negative rainfall anomalies are also significantly associated with a warm northern Atlantic in the austral autumn and a cold southern Atlantic in the spring. The northeastern Amazon rainfall anomalies are closely related with El Niño-southern oscillation during the whole year, whereas the relationships with the tropical Atlantic SST anomalies are mainly observed during the autumn. A time-space continuity is observed between El Niño-related rainfall anomalies in the northeastern Amazon, those in the northern Amazon and south-eastern Amazon, and those in northern South America and in the Nordeste of Brazil.A reinforcement of certain rainfall anomalies is observed when specific oceanic events combine. For instance, when El Niño and cold SSTs in the southern Atlantic are associated, very strong negative anomalies are observed in the whole northern Amazon basin. Nonetheless, the comparison of the cluster and the composite analyses results shows that the rainfall anomalies in the northeastern Amazon are not always associated with tropical SST anomalies.In the southern and western Amazon, significant tropical SST-related rainfall anomalies are very few and spatially variable. The precipitation origins differ from those of the northeastern Amazon: land temperature variability, extratropical perturbations and moisture advection are important rainfall factors, as well

Fishing for opinions: Stakeholder views on MSFD implementation in European Seas

NARCIS (Netherlands)

Hendriksen, A.; Jouanneau, C.; Koss, R.; Raakjaer, J.

2014-01-01

Stakeholder participation is vital when introducing and implementing ecosystem-based management (EBM) at any scale. This paper presents the results of a survey covering four European Regional Seas (Baltic Sea, Black Sea, Mediterranean Sea and North-East Atlantic Ocean) aimed to collect stakeholders¿

A microsatellite baseline for genetic stock identification of European Atlantic salmon (Salmo salar L.)

DEFF Research Database (Denmark)

Gilbey, John; Coughlan, Jamie; Wennevik, Vidar

2018-01-01

Atlantic salmon (Salmo salar L.) populations from different river origins mix in the North Atlantic during the marine life stage. To facilitate marine stock identification, we developed a genetic baseline covering the European component of the species' range excluding the Baltic Sea, from the Rus...

Contributions to the Pleistocene Coral Reefs of the Red Sea Coast, Egypt

International Nuclear Information System (INIS)

El-Sorogy, A.S.

2008-01-01

The Pleistocene coral reefs of the Red Sea coast form discontinuous strip in three morphological units, with elevations range from 10 to 35 m above the present sea level and with maximum width of about 550 m. The morphological steps of the studied reefal units are caused by on-lap during different sea levels, by tectonics, or by erosion during transgression. Facies patterns within reefs exhibit lateral and vertical changes. The lateral development of each unit begins at the shore, covering the whole lagoonal facies and ends at the upper reef slope. These changes either reflect transitions within the depositional environment or they are related to minor/major sea level fluctuations. The vertical pattern shows a transgressive sequence in the lower (youngest) and the upper (oldest) units and a regressive one in the middle unit. Eighty-eight scleractinian species have been identified. They belong to 3 suborders, 8 families and 27 genera. The straitigraphic range of the majority of the identified species, which have been previously recorded from the recent sediments of study area is extended here to the Pleistocene age. The paleo- and -biogeographic distribution of the studied species indicated that all belong to Indo-Pacific affinity as well as Atlantic-Mediterranean for very few. (author)

Vertical water mass structure in the North Atlantic influences the bathymetric distribution of species in the deep-sea coral genus Paramuricea

Science.gov (United States)

Radice, Veronica Z.; Quattrini, Andrea M.; Wareham, Vonda E.; Edinger, Evan N.; Cordes, Erik E.

2016-10-01

Deep-sea corals are the structural foundation of their ecosystems along continental margins worldwide, yet the factors driving their broad distribution are poorly understood. Environmental factors, especially depth-related variables including water mass properties, are thought to considerably affect the realized distribution of deep-sea corals. These factors are governed by local and regional oceanographic conditions that directly influence the dispersal of larvae, and therefore affect the ultimate distribution of adult corals. We used molecular barcoding of mitochondrial and nuclear sequences to identify species of octocorals in the genus Paramuricea collected from the Labrador Sea to the Grand Banks of Newfoundland, Canada at depths of 150-1500 m. The results of this study revealed overlapping bathymetric distributions of the Paramuricea species present off the eastern Canadian coast, including the presence of a few cryptic species previously designated as Paramuricea placomus. The distribution of Paramuricea species in the western North Atlantic differs from the Gulf of Mexico, where five Paramuricea species exhibit strong segregation by depth. The different patterns of Paramuricea species in these contrasting biogeographic regions provide insight into how water mass structure may shape species distribution. Investigating Paramuricea prevalence and distribution in conjunction with oceanographic conditions can help demonstrate the factors that generate and maintain deep-sea biodiversity.

The disposal of low-level radioactive waste into the sea

International Nuclear Information System (INIS)

Saruhashi, Katsuko

1979-01-01

Disposal of low-level radioactive wastes is made both on land and in sea. Though the land disposal has been already carried out in the U.S.A. and the U.S.S.R., it is impossible in the narrow land of Japan. In the United States, the wastes solidified with cement in drums were previously abandoned in deep seas of the Pacific and the Atlantic. This is no longer done presently; instead, the land disposal is employed due to its lower costs. In European countries, the sea disposal is performed under OECDNEA, trial disposal in 1961 and full-scale disposal since 1967, in the Atlantic. Meanwhile, in Japan, test sea disposal will be carried out in the near future in deep sea of the northern Pacific, the important sea area for fisheries. The international trends of the deep sea disposal of low-level wastes and the correspondent trends of the same in Japan, in the past years are described. (J.P.N.)

Sea Ice Retreat and its Impact on the Intensity of Open-Ocean Convection in the Greenland and Iceland Seas

Science.gov (United States)

Moore, K.; Våge, K.; Pickart, R. S.; Renfrew, I.

2016-12-01

The air-sea transfer of heat and freshwater plays a critical role in the global climate system. This is particularly true for the Greenland and Iceland Seas, where these fluxes drive ocean convection that contributes to Denmark Strait Overflow Water, the densest component of the lower limb of the Atlantic Meridional Overturning Circulation (AMOC). This buoyancy transfer is most pronounced during the winter downstream of the ice edge, where the cold and dry Arctic air first comes in contact with the relatively warm ocean surface. Here we show that the wintertime retreat of sea ice in the region, combined with different rates of warming for the atmosphere and sea surface of the Greenland and Iceland Seas, has resulted in statistically significant reductions of approximately 20% in the magnitude of the winter air-sea heat fluxes since 1979. Furthermore, it is demonstrated that modes of climate variability other than the North Atlantic Oscillation (NAO) are required to fully characterize the regional air-sea interaction in this region. Mixed-layer model simulations imply that a continued decrease in atmospheric forcing will exceed a threshold for the Greenland Sea whereby convection will become depth limited, reducing the ventilation of mid-depth waters in the Nordic Seas. In the Iceland Sea, further reductions have the potential to decrease the supply of the densest overflow waters to the AMOC.

On the differences between early and middle winter atmospheric responses to sea surface temperature anomalies in the northwest Atlantic

International Nuclear Information System (INIS)

Peng, S.; Mysak, L.A.; Derome, J.; Ritchie, H.; Dugas, B.

1994-01-01

Using an atmospheric global spectral model at RPN with T42 horizontal resolution, we have shown that the winter atmosphere in the mid-latitude is capable of reacting to the SST anomalies prescribed in the northwest Atlantic with two different responses. The nature of the response is determined by the climatological conditions of the winter system. Experiments are conducted using either the perpetual November or January conditions, with or without the SST anomalies prescribed. Six 50-day integrations, with positive (or negative) SST anomalies prescribed, initialized from independent November analyses and similarly, four runs initialized from January analyses, have been examined in comparison with their control runs

Forest productivity in southwestern Europe is controlled by coupled North Atlantic and Atlantic Multidecadal Oscillations.

Science.gov (United States)

Madrigal-González, Jaime; Ballesteros-Cánovas, Juan A; Herrero, Asier; Ruiz-Benito, Paloma; Stoffel, Markus; Lucas-Borja, Manuel E; Andivia, Enrique; Sancho-García, Cesar; Zavala, Miguel A

2017-12-20

The North Atlantic Oscillation (NAO) depicts annual and decadal oscillatory modes of variability responsible for dry spells over the European continent. The NAO therefore holds a great potential to evaluate the role, as carbon sinks, of water-limited forests under climate change. However, uncertainties related to inconsistent responses of long-term forest productivity to NAO have so far hampered firm conclusions on its impacts. We hypothesize that, in part, such inconsistencies might have their origin in periodical sea surface temperature anomalies in the Atlantic Ocean (i.e., Atlantic Multidecadal Oscillation, AMO). Here we show strong empirical evidence in support of this hypothesis using 120 years of periodical inventory data from Iberian pine forests. Our results point to AMO + NAO + and AMO - NAO - phases as being critical for forest productivity, likely due to decreased winter water balance and abnormally low winter temperatures, respectively. Our findings could be essential for the evaluation of ecosystem functioning vulnerabilities associated with increased climatic anomalies under unprecedented warming conditions in the Mediterranean.

Portrait of a Warming Ocean and Rising Sea Levels: Trend of Sea Level Change 1993-2008

Science.gov (United States)

2008-01-01

area of rising sea levels in the North Atlantic where sea levels are usually low. This large pool of rapidly rising warm water is evidence of a major change in ocean circulation. It signals a slow down in the sub-polar gyre, a counter-clockwise system of currents that loop between Ireland, Greenland and Newfoundland. Such a change could have an impact on climate since the sub-polar gyre may be connected in some way to the nearby global thermohaline circulation, commonly known as the global conveyor belt. This is the slow-moving circulation in which water sinks in the North Atlantic at different locations around the sub-polar gyre, spreads south, travels around the globe, and slowly up-wells to the surface before returning around the southern tip of Africa. Then it winds its way through the surface currents in the Atlantic and eventually comes back to the North Atlantic. It is unclear if the weakening of the North Atlantic sub-polar gyre is part of a natural cycle or related to global warming. This image was made possible by the detailed record of sea surface height measurements begun by Topex/Poseidon and continued by Jason-1. The recently launched Ocean Surface Topography Mission on the Jason-2 satellite (OSTM/Jason-2) will soon take over this responsibility from Jason-1. The older satellite will move alongside OSTM/Jason-2 and continue to measure sea surface height on an adjacent ground track for as long as it is in good health. Topex/Poseidon and Jason-1 are joint missions of NASA and the French space agency, CNES. OSTM/Jason-2 is collaboration between NASA; the National Oceanic and Atmospheric Administration; CNES; and the European Organisation for the Exploitation of Meteorological Satellites. JPL manages the U.S. portion of the missions for NASA's Science Mission Directorate, Washington, D.C.

Detection of human influence on sea-level pressure.

Science.gov (United States)

Gillett, Nathan P; Zwiers, Francis W; Weaver, Andrew J; Stott, Peter A

2003-03-20

Greenhouse gases and tropospheric sulphate aerosols--the main human influences on climate--have been shown to have had a detectable effect on surface air temperature, the temperature of the free troposphere and stratosphere and ocean temperature. Nevertheless, the question remains as to whether human influence is detectable in any variable other than temperature. Here we detect an influence of anthropogenic greenhouse gases and sulphate aerosols in observations of winter sea-level pressure (December to February), using combined simulations from four climate models. We find increases in sea-level pressure over the subtropical North Atlantic Ocean, southern Europe and North Africa, and decreases in the polar regions and the North Pacific Ocean, in response to human influence. Our analysis also indicates that the climate models substantially underestimate the magnitude of the sea-level pressure response. This discrepancy suggests that the upward trend in the North Atlantic Oscillation index (corresponding to strengthened westerlies in the North Atlantic region), as simulated in a number of global warming scenarios, may be too small, leading to an underestimation of the impacts of anthropogenic climate change on European climate.

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

Distribution and long-range transport of polyfluoroalkyl substances in the Arctic, Atlantic Ocean and Antarctic coast

International Nuclear Information System (INIS)

Zhao Zhen; Xie Zhiyong; Möller, Axel; Sturm, Renate; Tang Jianhui; Zhang Gan; Ebinghaus, Ralf

2012-01-01

The global distribution and long-range transport of polyfluoroalkyl substances (PFASs) were investigated using seawater samples collected from the Greenland Sea, East Atlantic Ocean and the Southern Ocean in 2009–2010. Elevated levels of ΣPFASs were detected in the North Atlantic Ocean with the concentrations ranging from 130 to 650 pg/L. In the Greenland Sea, the ΣPFASs concentrations ranged from 45 to 280 pg/L, and five most frequently detected compounds were perfluorooctanoic acid (PFOA), perfluorohexanesulfonate (PFHxS), perfluorohexanoic acid (PFHxA), perfluorooctane sulfonate (PFOS) and perfluorobutane sulfonate (PFBS). PFOA (15 pg/L) and PFOS (25–45 pg/L) were occasionally found in the Southern Ocean. In the Atlantic Ocean, the ΣPFASs concentration decreased from 2007 to 2010. The elevated PFOA level that resulted from melting snow and ice in Greenland Sea implies that the Arctic may have been driven by climate change and turned to be a source of PFASs for the marine ecosystem. - Highlights: ► PFOA is released from the Arctic snow and ice and might be transport southwards to the Atlantic. ► Decline temporal trends of PFASs are present in the Northern Hemisphere in the Atlantic. ► PFOS has elevate concentration in comparison to PFOA in the Southern Ocean. - Polyfluoroalkyl substances (PFASs) have been reported for the Arctic, Atlantic and the Southern Ocean, which improves understanding the fate of PFASs in the global oceans.

A new Liopropoma sea bass (Serranidae, Epinephelinae, Liopropomini) from deep reefs off Curaçao, southern Caribbean, with comments on depth distributions of western Atlantic liopropomins

Science.gov (United States)

Baldwin, Carole C.; Robertson, D. Ross

2014-01-01

Collecting reef-fish specimens using a manned submersible diving to 300 m off Curaçao, southern Caribbean, is resulting in the discovery of numerous new fish species. The new Liopropoma sea bass described here differs from other western Atlantic members of the genus in having VIII, 13 dorsal-fin rays; a moderately indented dorsal-fin margin; a yellow-orange stripe along the entire upper lip; a series of approximately 13 white, chevron-shaped markings on the ventral portion of the trunk; and a reddish-black blotch on the tip of the lower caudal-fin lobe. The new species, with predominantly yellow body and fins, closely resembles the other two “golden basses” found together with it at Curaçao: L. aberransand L. olneyi. It also shares morphological features with the other western Atlantic liopropomin genus,Bathyanthias. Preliminary phylogenetic data suggest that western Atlantic liopropomins, includingBathyanthias, are monophyletic with respect to Indo-Pacific Liopropoma, and that Bathyanthias is nested within Liopropoma, indicating a need for further study of the generic limits of Liopropoma. The phylogenetic data also suggest that western Atlantic liopropomins comprise three monophyletic clades that have overlapping depth distributions but different depth maxima (3–135 m, 30–150 m, 133–411 m). The new species has the deepest depth range (182–241 m) of any known western Atlantic Liopropomaspecies. Both allopatric and depth-mediated ecological speciation may have contributed to the evolution of western Atlantic Liopropomini.

Evidence for external forcing of the Atlantic Multidecadal Oscillation since termination of the Little Ice Age.

Science.gov (United States)

Knudsen, Mads Faurschou; Jacobsen, Bo Holm; Seidenkrantz, Marit-Solveig; Olsen, Jesper

2014-02-25

The Atlantic Multidecadal Oscillation (AMO) represents a significant driver of Northern Hemisphere climate, but the forcing mechanisms pacing the AMO remain poorly understood. Here we use the available proxy records to investigate the influence of solar and volcanic forcing on the AMO over the last ~450 years. The evidence suggests that external forcing played a dominant role in pacing the AMO after termination of the Little Ice Age (LIA; ca. 1400-1800), with an instantaneous impact on mid-latitude sea-surface temperatures that spread across the North Atlantic over the ensuing ~5 years. In contrast, the role of external forcing was more ambiguous during the LIA. Our study further suggests that the Atlantic Meridional Overturning Circulation is important for linking external forcing with North Atlantic sea-surface temperatures, a conjecture that reconciles two opposing theories concerning the origin of the AMO.

On the Influence of Global Warming on Atlantic Hurricane Frequency

Science.gov (United States)

Hosseini, S. R.; Scaioni, M.; Marani, M.

2018-04-01

In this paper, the possible connection between the frequency of Atlantic hurricanes to the climate change, mainly the variation in the Atlantic Ocean surface temperature has been investigated. The correlation between the observed hurricane frequency for different categories of hurricane's intensity and Sea Surface Temperature (SST) has been examined over the Atlantic Tropical Cyclogenesis Regions (ACR). The results suggest that in general, the frequency of hurricanes have a high correlation with SST. In particular, the frequency of extreme hurricanes with Category 5 intensity has the highest correlation coefficient (R = 0.82). In overall, the analyses in this work demonstrates the influence of the climate change condition on the Atlantic hurricanes and suggest a strong correlation between the frequency of extreme hurricanes and SST in the ACR.

Revised estimate for the radiocarbon age of North Atlantic deep water

International Nuclear Information System (INIS)

Broecker, W.S.

1979-01-01

The extent to which the admixture of water of Antarctic origin influences the 14 C/C ratio in North Atlantic deep water (NADW) has been heretofore underestimated. When this correction is properly made, a ventilation time for the deep western Atlantic is reduced to only about 100 years. The production rate of the northern component of NADW entering the western basin must be of the order of 30 Sv. If this northern component water is assumed to be the major supplier of new 14 C to the deep sea, the carbon isotope ventilation time of the world deep ocean must be of the order of 900 years. However, since the new deep waters formed around the perimeter of the Antarctic are thought to enter the deep sea at a rate of about 20 Sv, the water ventilation time for the deep sea is of the order of 550 years

The late Wisconsinan and Holocene record of Walrus (Odobenus rosmarus) from North America: A review with new data from Arctic and Atlantic Canada

Science.gov (United States)

Dyke, A.S.; Hooper, J.; Harington, C.R.; Savelle, J.M.

1999-01-01

The Late Wisconsinan and Holocene record of the Atlantic walrus is known from numerous collections of bones and tusks from Arctic Canada and south to North Carolina, as well as from many archaeological sites in the Arctic and Subarctic. In contrast, the Pacific walrus has no dated Late Wisconsinan or early Holocene record in North America, and it may have been displaced into the northwest Pacific at Last Glacial Maximum (LGM). The Atlantic walrus rapidly exploited newly deglaciated territory, moving northward from its LGM refugium and reaching the Bay of Fundy by 12800 B.P., the Grand Banks by 12500 B.P., southern Labrador by 11500 B.P., and the central Canadian Arctic Archipelago (CAA) by 9700 B.P. Its southern range limit may have retracted to the Bay of Fundy by ca. 7500 B.P. Within the CAA, walrus remains cluster in two main age groups: 9700 to 8500 B.P. and 5000 to 4/3000 B.P. This pattern strongly resembles the distribution of bowhead whale radiocarbon ages from the same area, which suggests a common control by sea-ice conditions. Walrus remains occur in Indian culture archaeological sites as old as 7500 B.P. and, in some cases (Namu, British Columbia, and Mackinac Island, Michigan), they evidently represent long-distance human transport. They are much more common in Paleoeskimo and Neoeskimo culture sites. However, they occur in very low abundances, and generally as debitage, in sites older than Dorset (2500 B.P.). The walrus, therefore, may not have been hunted by early Paleoeskimos. Beginning with Early Dorset, walrus remains occur in definite diet-related contexts. Middle Dorset (2300 to 1500 B.P.) and late Thule (High Arctic, and there may be a similar gap in the middle Pre-Dorset (3400 to 2600 B.P.). Sea-ice conditions at these times may have adversely affected availability of walrus and other marine mammal resources. Walrus is a prominent faunal element in Middle Dorset sites on the Labrador coast; this is consistent with a southward displacement of

Interdecadal North-Atlantic meridional overturning circulation variability in EC-EARTH

Energy Technology Data Exchange (ETDEWEB)

Wouters, Bert; Drijfhout, Sybren; Hazeleger, Wilco

2012-12-15

The Atlantic meridional overturning circulation (AMOC) in a 600 years pre-industrial run of the newly developed EC-EARTH model features marked interdecadal variability with a dominant time-scale of 50-60 years. An oscillation of approximately 2 Sverdrup (1 Sv = 10{sup 6} m{sup 3} s{sup -1}) is identified, which manifests itself as a monopole causing the overturning to simultaneously strengthen (/weaken) and deepen (/shallow) as a whole. Eight years before the AMOC peaks, density in the Labrador-Irminger Sea region reaches a maximum, triggering deep water formation. This density change is caused by a counterclockwise advection of temperature and salinity anomalies at lower latitudes, which we relate to the north-south excursions of the subpolar-subtropical gyre boundary and variations in strength and position of the subpolar gyre and the North Atlantic Current. The AMOC fluctuations are not directly forced by the atmosphere, but occur in a delayed response of the ocean to forcing by the North Atlantic Oscillation, which initiates ''intergyre''-gyre fluctuations. Associated with the AMOC is a 60-year sea surface temperature variability in the Atlantic, with a pattern and timescale showing similarities with the real-world Atlantic Multidecadal Variability. This good agreement with observations lends a certain degree of credibility that the mechanism that is described in this article could be seen as representative of the real climate system. (orig.)

Dispersion in North Atlantic Deep Water transfer between the northern source region and the South Atlantic

Energy Technology Data Exchange (ETDEWEB)

Huhn, Oliver; Roether, Wolfgang [Institut fuer Umweltphysik, Universitaet Bremen (Germany)

2007-07-01

North Atlantic Deep Water (NADW) represents the Atlantic part of the deep, southward return arm of the oceanic 'conveyor belt', which moderates Europe's climate and effects most of the water transfer from the ocean surface into the deep waters globally. The transfer starts from the NADW formation regions, which in the case of upper NADW (approx. 1500-2000 m depth) is the Labrador Sea (far NW Atlantic). NADW is found concentrated toward the continental slope of the Americas, but subject to meandering, and to recirculation into, and mixing with, the waters of the interior Atlantic. Individual water parcels thus follow a complex ensemble of trajectories. We have obtained characteristics of that ensemble by fitting the free parameters of a suitable function using extensive observations of the transient tracers CFC-11, CFC-12, CCl{sub 4}, and tritium. A tracer transfer function of ocean-surface concentrations to those in newly formed NADW was derived as a precursory step. In the upper NADW we obtain RMS transfer-time dispersions on the way from the Labrador Sea of 31 years at 6 N rising to 53 years at 20 S, compared to mean transfer times ranging 46 to 79 years ({+-}20 %); furthermore, approximately 10 % to 40 % of the water is old, tracer-free water admixed on the way. Similar results have been obtained for lower NADW (approx. 2500-4000 m). The combination of tritium and CFC observations is particularly suited to constrain the dispersion, since it acts on the concentrations of these tracers in an opposite way. The tracer-adjusted transfer functions allow quantification of the NADW transport of pollutants and other compounds delivered to the NADW formation region. The results can furthermore check mean transfer times and large-scale dispersion of the NADW part of dynamic ocean circulation models.

Global Climate Change Consequences Changing the Middle Sea Level in the Brazilian Coast: Impacts on Ceará State

Science.gov (United States)

Lacerda, E. G.; Pires, L. B. M.; Pinto, V. K. E.

2015-12-01

Since the Industrial Revolution, man started to generate increasing amounts of waste and pollutants, which on a large scale in the long term is causing a series of climate change consequences, both globally as well as locally. One of the many effects of these changes has been reflected in the ocean levels, depending on various factors. Thus, the population living in coastal areas suffers from the negative effects of the advancement of ocean waters. The coast of northeastern Brazil is an example of this, especially the state of Ceará coast. The state of Ceará has 573 km of coastline, a region that has suffered extensive erosion, in which the Middle Sea Level (MSL) changes exert a significant influence. The coastal plain is a strip of land of small extent, with an average width of 2.5 km, formed depending on the availability of high sediment stocks provided through the action of wind, marine, or river processes, individually in combination with each other. In many beaches it is observed that the strip of beach is narrow due to the presence of topographic elevations carved into sharp cliffs. Between periods of high tide and low tide, often rocky beach features are observed that have recently formed. The waves control the stretches of beach which are mostly sandy. This paper presents a survey about the evidence already apparent on the rise in the MSL and correlates it with the advance of the sea on the coast of Ceará, as well as assesses the possible consequences of this process. Therefore, a literature search was conducted in relevant scientific publications. The data used are from the station "Global Sea Level Observing System - GLOSS" which maintains a tide gauge installed in Ceará in Fortaleza. The analyses show that the phenomenon has caused a lot of inconvenience to the people, streets have disappeared, as well as several buildings located along the coast. The sea advances destroyed beaches and have promoted an accelerated level of erosion, changing the

Deep-sea scleractinian coral age and depth distributions in the northwest Atlantic for the last 225,000 years

Science.gov (United States)

Robinson, L.F.; Adkins, J.F.; Scheirer, D.S.; Fernandez, D.P.; Gagnon, A.; Waller, R.G.

2007-01-01

Deep-sea corals have grown for over 200,000 yrs on the New England Seamounts in the northwest Atlantic, and this paper describes their distribution both with respect to depth and time. Many thousands of fossil scleractinian corals were collected on a series of cruises from 2003-2005; by contrast, live ones were scarce. On these seamounts, the depth distribution of fossil Desmophyllum dianthus (Esper, 1794) is markedly different to that of the colonial scleractinian corals, extending 750 m deeper in the water column to a distinct cut-off at 2500 m. This cut-off is likely to be controlled by the maximum depth of a notch-shaped feature in the seamount morphology. The ages of D. dianthus corals as determined by U-series measurements range from modern to older than 200,000 yrs. The age distribution is not constant over time, and most corals have ages from the last glacial period. Within the glacial period, increases in coral population density at Muir and Manning Seamounts coincided with times at which large-scale ocean circulation changes have been documented in the deep North Atlantic. Ocean circulation changes have an effect on coral distributions, but the cause of the link is not known. ?? 2007 Rosenstiel School of Marine and Atmospheric Science of the University of Miami.

Sea-Level Rise Implications for Coastal Protection from Southern Mediterranean to the U.S.A. Atlantic Coast

Science.gov (United States)

Ismail, Nabil; Williams, Jeffress

2013-04-01

This paper presents an assessment of global sea level rise and the need to incorporate projections of rise into management plans for coastal adaptation. It also discusses the performance of a shoreline revetment; M. Ali Seawall, placed to protect the land against flooding and overtopping at coastal site, within Abu Qir Bay, East of Alexandria, Egypt along the Nile Delta coast. The assessment is conducted to examine the adequacy of the seawall under the current and progressive effects of climate change demonstrated by the anticipated sea level rise during this century. The Intergovernmental Panel on Climate Change (IPCC, 2007) predicts that the Mediterranean will rise 30 cm to 1 meter this century. Coastal zone management of the bay coastline is of utmost significance to the protection of the low agricultural land and the industrial complex located in the rear side of the seawall. Moreover this joint research work highlights the similarity of the nature of current and anticipated coastal zone problems, at several locations around the world, and required adaptation and protection measures. For example many barrier islands in the world such as that in the Atlantic and Gulf of Mexico coasts of the U.S., lowland and deltas such as in Italy and the Nile Delta, and many islands are also experiencing significant levels of erosion and flooding that are exacerbated by sea level rise. Global Climatic Changes: At a global scale, an example of the effects of accelerated climate changes was demonstrated. In recent years, the impacts of natural disasters are more and more severe on coastal lowland areas. With the threats of climate change, sea level rise storm surge, progressive storm and hurricane activities and potential subsidence, the reduction of natural disasters in coastal lowland areas receives increased attention. Yet many of their inhabitants are becoming increasingly vulnerable to flooding, and conversions of land to open ocean. These global changes were recently

76 FR 66260 - Fisheries of the Northeastern United States; Atlantic Mackerel, Squid, and Butterfish Fisheries...

Science.gov (United States)

2011-10-26

...) of scup, 184,280 lb (83,588 kg) of black sea bass, and 200,000 lb (90,718 kg) of bluefish. Project... summer flounder, scup, black sea bass, longfin squid, butterfish, and Atlantic bluefish, and assessment...

Structure and Evolution of Thermohaline Staircases in Tropical North Atlantic

National Research Council Canada - National Science Library

Wall, Steven

2007-01-01

.... Salt finger convection is generally observed in mid-latitude regions, particularly in the Atlantic Ocean and Mediterranean Sea, between the hase of the mixed layer and the top of the intermediate water...

GHRSST Level 3C Atlantic sub-skin Sea Surface Temperature from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) on MSG at 0 degree longitude (GDS V2) produced by OSI SAF (GDS version 2)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) dataset for the Eastern Atlantic Region from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI)...

An Atlantic influence on Amazon rainfall

Energy Technology Data Exchange (ETDEWEB)

Yoon, Jin-Ho [University of Maryland, Department of Atmospheric and Oceanic Science, College Park, MD (United States); Zeng, Ning [University of Maryland, Earth System Science Interdisciplinary Center, College Park, MD (United States); University of Maryland, Department of Atmospheric and Oceanic Science, College Park, MD (United States)

2010-02-15

Rainfall variability over the Amazon basin has often been linked to variations in Pacific sea surface temperature (SST), and in particular, to the El Nino/Southern Oscillation (ENSO). However, only a fraction of Amazon rainfall variability can be explained by ENSO. Building upon the recent work of Zeng (Environ Res Lett 3:014002, 2008), here we provide further evidence for an influence on Amazon rainfall from the tropical Atlantic Ocean. The strength of the North Atlantic influence is found to be comparable to the better-known Pacific ENSO connection. The tropical South Atlantic Ocean also shows some influence during the wet-to-dry season transition period. The Atlantic influence is through changes in the north-south divergent circulation and the movement of the ITCZ following warm SST. Therefore, it is strongest in the southern part of the Amazon basin during the Amazon's dry season (July-October). In contrast, the ENSO related teleconnection is through anomalous east-west Walker circulation with largely concentrated in the eastern (lower) Amazon. This ENSO connection is seasonally locked to boreal winter. A complication due to the influence of ENSO on Atlantic SST causes an apparent North Atlantic SST lag of Amazon rainfall. Removing ENSO from North Atlantic SST via linear regression resolves this causality problem in that the residual Atlantic variability correlates well and is in phase with the Amazon rainfall. A strong Atlantic influence during boreal summer and autumn is particularly significant in terms of the impact on the hydro-ecosystem which is most vulnerable during the dry season, as highlighted by the severe 2005 Amazon drought. Such findings have implications for both seasonal-interannual climate prediction and understanding the longer-term changes of the Amazon rainforest. (orig.)

Enhanced Open Ocean Storage of CO2 from Shelf Sea Pumping

NARCIS (Netherlands)

Thomas, H.; Bozec, Y.; Elkalay, K.; de Baar, H.J.W.

2004-01-01

Seasonal field observations show that the North Sea, a Northern European shelf sea, is highly efficient in pumping carbon dioxide fromthe atmosphere to the North Atlantic Ocean. The bottom topography–controlled stratification separates production and respiration processes in the North Sea, causing a

Temporal, spatial, and body size effects on growth rates of loggerhead sea turtles (Caretta caretta) in the Northwest Atlantic

Science.gov (United States)

Bjorndal, Karen A.; Schroeder, Barbara A.; Foley, Allen M.; Witherington, Blair E.; Bresette, Michael; Clark, David; Herren, Richard M.; Arendt, Michael D.; Schmid, Jeffrey R.; Meylan, Anne B.; Meylan, Peter A.; Provancha, Jane A.; Hart, Kristen M.; Lamont, Margaret M.; Carthy, Raymond R.; Bolten, Alan B.

2013-01-01

In response to a call from the US National Research Council for research programs to combine their data to improve sea turtle population assessments, we analyzed somatic growth data for Northwest Atlantic (NWA) loggerhead sea turtles (Caretta caretta) from 10 research programs. We assessed growth dynamics over wide ranges of geography (9–33°N latitude), time (1978–2012), and body size (35.4–103.3 cm carapace length). Generalized additive models revealed significant spatial and temporal variation in growth rates and a significant decline in growth rates with increasing body size. Growth was more rapid in waters south of the USA (productivity to a common environmental change should be explored to determine whether somatic growth rates can help interpret population trends based on annual counts of nests or nesting females. Because of the significant spatial and temporal variation in growth rates, population models of NWA loggerheads should avoid employing growth data from restricted spatial or temporal coverage to calculate demographic metrics such as age at sexual maturity.

75 FR 57240 - Atlantic Highly Migratory Species; 2011 Commercial Fishing Season and Adaptive Management...

Science.gov (United States)

2010-09-20

... sharks (other than porbeagle and blue sharks) in the northwestern Atlantic Ocean, including the Gulf of... the Atlantic Ocean, Gulf of Mexico, and Caribbean Sea. NMFS has split the non-sandbar LCS quota... Horizon oil spill) or small scale issues (e.g., inclement weather or slight shifts in migratory patterns...

Barriers to gene flow in the marine environment: insights from two common intertidal limpet species of the Atlantic and Mediterranean.

Directory of Open Access Journals (Sweden)

Alexandra Sá-Pinto

Full Text Available Knowledge of the scale of dispersal and the mechanisms governing gene flow in marine environments remains fragmentary despite being essential for understanding evolution of marine biota and to design management plans. We use the limpets Patella ulyssiponensis and Patella rustica as models for identifying factors affecting gene flow in marine organisms across the North-East Atlantic and the Mediterranean Sea. A set of allozyme loci and a fragment of the mitochondrial gene cytochrome C oxidase subunit I were screened for genetic variation through starch gel electrophoresis and DNA sequencing, respectively. An approach combining clustering algorithms with clinal analyses was used to test for the existence of barriers to gene flow and estimate their geographic location and abruptness. Sharp breaks in the genetic composition of individuals were observed in the transitions between the Atlantic and the Mediterranean and across southern Italian shores. An additional break within the Atlantic cluster separates samples from the Alboran Sea and Atlantic African shores from those of the Iberian Atlantic shores. The geographic congruence of the genetic breaks detected in these two limpet species strongly supports the existence of transpecific barriers to gene flow in the Mediterranean Sea and Northeastern Atlantic. This leads to testable hypotheses regarding factors restricting gene flow across the study area.

North sea: a quarter of total's reserves (excluding the Middle East)

International Nuclear Information System (INIS)

Anon.

1995-01-01

In 1994, for the fifth successive year, Total increased its proven reserves of hydrocarbons which reach 4.3 Gboe (+ 6% compared to 1993). Outside the Middle East, the reserves show a development of 9% and reach the threshold of 2 Gboe. In 1994, Total's production of hydrocarbons reached 633,000 boe/d (+ 4%), despite a fall of 3% in oil production in the Middle East. Excluding the Middle East, production was increased to 345,000 boe/d (+ 12%), including 212,000 boe/d for gas (+ 20%). Exploration/production investments were 5.8 GF in 1994 (excluding labour) and the development program for reserves and production for the coming years is based on yearly investments of some 6 GF. Total's production in Europe, essentially in the North Sea, was 154,000 boe/d in 1994 (+ 12%). This zone has potential for significant growth for the group which has undertaken exploration surveys in the Western Shetlands and in Haltenbanken. In the British zone, the Dunbar field and its neighbour Ellon were brought into production in December 1994. In the Norwegian zone, the Froy field, was brought into production last June. In the Lille-Frigg field, whose production started in May, initial reserves are estimated at 6,7 Bcm of gas. Total Norge AS also has interests in the producing fields of Ekofisk, Frigg, East-Frigg, Heimdal, Sleipner East, Veslefrikk, Oseberg, Brage, in those of Sleipner West and Huldra (start-up scheduled for 1997) and in Troll (phase 1) which should be producing in 1996. In the Dutch zone, the K4b and K5a blocks brought into production last November hold reserves estimated at 20 Bcm; their production could reach 2 Bcm/year as from 1995. (authors). 1 tab., 1 photo

Turtle riders: remoras on marine turtles in Southwest Atlantic

Directory of Open Access Journals (Sweden)

Ivan Sazima

Full Text Available An overview is presented for a poorly documented relationship between reef vertebrates in Southwest Atlantic: remoras (Echeneidae associated with marine turtles. Two remora species (Echeneis naucrates and Remora remora and four turtle species (Caretta caretta, Chelonia mydas, Eretmochelys imbricata, and Dermochelys coriacea are here recorded in symbiotic associations in the SW Atlantic. Echeneis naucrates was recorded both on the coast and on oceanic islands, whereas R. remora was recorded only at oceanic islands and in the open sea. The remora-turtle association is usually regarded as an instance of phoresis (hitchhiking, albeit feeding by the fish is also involved in this symbiosis type. This association seems to be rare in SW Atlantic.

Distribution and long-range transport of polyfluoroalkyl substances in the Arctic, Atlantic Ocean and Antarctic coast.

Science.gov (United States)

Zhao, Zhen; Xie, Zhiyong; Möller, Axel; Sturm, Renate; Tang, Jianhui; Zhang, Gan; Ebinghaus, Ralf

2012-11-01

The global distribution and long-range transport of polyfluoroalkyl substances (PFASs) were investigated using seawater samples collected from the Greenland Sea, East Atlantic Ocean and the Southern Ocean in 2009-2010. Elevated levels of ΣPFASs were detected in the North Atlantic Ocean with the concentrations ranging from 130 to 650 pg/L. In the Greenland Sea, the ΣPFASs concentrations ranged from 45 to 280 pg/L, and five most frequently detected compounds were perfluorooctanoic acid (PFOA), perfluorohexanesulfonate (PFHxS), perfluorohexanoic acid (PFHxA), perfluorooctane sulfonate (PFOS) and perfluorobutane sulfonate (PFBS). PFOA (15 pg/L) and PFOS (25-45 pg/L) were occasionally found in the Southern Ocean. In the Atlantic Ocean, the ΣPFASs concentration decreased from 2007 to 2010. The elevated PFOA level that resulted from melting snow and ice in Greenland Sea implies that the Arctic may have been driven by climate change and turned to be a source of PFASs for the marine ecosystem. Copyright © 2012 Elsevier Ltd. All rights reserved.

Microbial processes in North Atlantic pelagic sediments, and potential risks of deep-sea waste disposal

International Nuclear Information System (INIS)

Bolliger, R.; Hanselmann, K.W.; Bachofen, R.

1989-01-01

From the results for waste disposal on deep sea sediments, it was concluded: As waste canisters are buried in the sediment to a depth of 15 to 20 cm, they are in contact with the zone that contains the highest potential bacterial activity through a relatively large surface. An input of oxidizable organic matter to the sediment surface zone will stimulate microbial activity and therefore increase the risk for solubilization and redistribution of elements in the ocean water. Waste canisters lying on the sediment surface cut off the oxygen supply from the ocean water and ease the shift to anaerobiosis. This initiates microbial activities through which metals are changed into their mobile species as a consequence of the altered environmental redox potential. The risk for steel corrosion by hydrogen sulfide, which could be produced by sulfate reducing bacteria, is minimal since this physiological group is not active in the North Atlantic sediments examined

External forcing as a metronome for Atlantic multidecadal variability

Science.gov (United States)

Otterå, Odd Helge; Bentsen, Mats; Drange, Helge; Suo, Lingling

2010-10-01

Instrumental records, proxy data and climate modelling show that multidecadal variability is a dominant feature of North Atlantic sea-surface temperature variations, with potential impacts on regional climate. To understand the observed variability and to gauge any potential for climate predictions it is essential to identify the physical mechanisms that lead to this variability, and to explore the spatial and temporal characteristics of multidecadal variability modes. Here we use a coupled ocean-atmosphere general circulation model to show that the phasing of the multidecadal fluctuations in the North Atlantic during the past 600 years is, to a large degree, governed by changes in the external solar and volcanic forcings. We find that volcanoes play a particularly important part in the phasing of the multidecadal variability through their direct influence on tropical sea-surface temperatures, on the leading mode of northern-hemisphere atmosphere circulation and on the Atlantic thermohaline circulation. We suggest that the implications of our findings for decadal climate prediction are twofold: because volcanic eruptions cannot be predicted a decade in advance, longer-term climate predictability may prove challenging, whereas the systematic post-eruption changes in ocean and atmosphere may hold promise for shorter-term climate prediction.

Quantifying the ocean, freshwater and human effects on year-to-year variability of one-sea-winter Atlantic salmon angled in multiple Norwegian rivers.

Science.gov (United States)

Otero, Jaime; Jensen, Arne J; L'Abée-Lund, Jan Henning; Stenseth, Nils Chr; Storvik, Geir O; Vøllestad, Leif Asbjørn

2011-01-01

Many Atlantic salmon, Salmo salar, populations are decreasing throughout the species' distributional range probably due to several factors acting in concert. A number of studies have documented the influence of freshwater and ocean conditions, climate variability and human impacts resulting from impoundment and aquaculture. However, most previous research has focused on analyzing single or only a few populations, and quantified isolated effects rather than handling multiple factors in conjunction. By using a multi-river mixed-effects model we estimated the effects of oceanic and river conditions, as well as human impacts, on year-to-year and between-river variability across 60 time series of recreational catch of one-sea-winter salmon (grilse) from Norwegian rivers over 29 years (1979-2007). Warm coastal temperatures at the time of smolt entrance into the sea and increased water discharge during upstream migration of mature fish were associated with higher rod catches of grilse. When hydropower stations were present in the course of the river systems the strength of the relationship with runoff was reduced. Catches of grilse in the river increased significantly following the reduction of the harvesting of this life-stage at sea. However, an average decreasing temporal trend was still detected and appeared to be stronger in the presence of salmon farms on the migration route of smolts in coastal/fjord areas. These results suggest that both ocean and freshwater conditions in conjunction with various human impacts contribute to shape interannual fluctuations and between-river variability of wild Atlantic salmon in Norwegian rivers. Current global change altering coastal temperature and water flow patterns might have implications for future grilse catches, moreover, positioning of aquaculture facilities as well as the implementation of hydropower schemes or other encroachments should be made with care when implementing management actions and searching for solutions to

Quantifying the ocean, freshwater and human effects on year-to-year variability of one-sea-winter Atlantic salmon angled in multiple Norwegian rivers.

Directory of Open Access Journals (Sweden)

Jaime Otero

Full Text Available Many Atlantic salmon, Salmo salar, populations are decreasing throughout the species' distributional range probably due to several factors acting in concert. A number of studies have documented the influence of freshwater and ocean conditions, climate variability and human impacts resulting from impoundment and aquaculture. However, most previous research has focused on analyzing single or only a few populations, and quantified isolated effects rather than handling multiple factors in conjunction. By using a multi-river mixed-effects model we estimated the effects of oceanic and river conditions, as well as human impacts, on year-to-year and between-river variability across 60 time series of recreational catch of one-sea-winter salmon (grilse from Norwegian rivers over 29 years (1979-2007. Warm coastal temperatures at the time of smolt entrance into the sea and increased water discharge during upstream migration of mature fish were associated with higher rod catches of grilse. When hydropower stations were present in the course of the river systems the strength of the relationship with runoff was reduced. Catches of grilse in the river increased significantly following the reduction of the harvesting of this life-stage at sea. However, an average decreasing temporal trend was still detected and appeared to be stronger in the presence of salmon farms on the migration route of smolts in coastal/fjord areas. These results suggest that both ocean and freshwater conditions in conjunction with various human impacts contribute to shape interannual fluctuations and between-river variability of wild Atlantic salmon in Norwegian rivers. Current global change altering coastal temperature and water flow patterns might have implications for future grilse catches, moreover, positioning of aquaculture facilities as well as the implementation of hydropower schemes or other encroachments should be made with care when implementing management actions and searching

Ancient deep-sea sponge grounds on the Flemish Cap and Grand Bank, northwest Atlantic.

Science.gov (United States)

Murillo, F J; Kenchington, E; Lawson, J M; Li, G; Piper, D J W

Recent studies on deep-sea sponges have focused on mapping contemporary distributions while little work has been done to map historical distributions; historical distributions can provide valuable information on the time frame over which species have co-evolved and may provide insight into the reasons for their persistence or decline. Members of the sponge family Geodiidae are dominant members of deep-sea sponge assemblages in the northwestern Atlantic. They possess unique spicules called sterrasters, which undergo little transport in sediment and can therefore indicate the Geodiidae sponge historical presence when found in sediment cores. This study focuses on the slopes of Flemish Cap and Grand Bank, important fishing grounds off the coast of Newfoundland, Canada, in international waters. Sediment cores collected in 2009 and 2010 were visually inspected for sponge spicules. Cores containing spicules were sub-sampled and examined under a light microscope for the presence of sterrasters. These cores were also dated using X-radiographs and grouped into five time categories based on known sediment horizons, ranging from 17,000 years BP to the present. Chronological groupings identified Geodiidae sponges in four persistent sponge grounds. The oldest sterrasters were concentrated in the eastern region of the Flemish Cap and on the southeastern slope of the Grand Bank. Opportunistic sampling of a long core in the southeastern region of the Flemish Cap showed the continuous presence of sponge spicules to more than 130 ka BP. Our results indicate that the geodiids underwent a significant range expansion following deglaciation, and support a contemporary distribution that is not shaped by recent fishing activity.

Amplified North Atlantic Warming in the Late Pliocene by Changes in Arctic Gateways

Science.gov (United States)

Otto-Bliesner, B. L.; Jahn, A.; Feng, R.; Brady, E. C.; Hu, A.; Lofverstrom, M.

2017-12-01

Reconstructions of the late Pliocene (mid-Piacenzian, 3.3 - 3.0 million years ago) sea surface temperature (SST) find much warmer conditions in the North Atlantic than modern. The much warmer SSTs, up to 8.8°C from sites with good dating and replicates from several different types of proxies, have been difficult for climate models to reproduce. Even with the slow feedbacks of a reduced Greenland ice sheet and expansion of boreal forests to the Arctic Ocean over Canada and Eurasia, models cannot warm the North Atlantic sufficiently to match the reconstructed SSTs. An enhancement of the Atlantic Meridional Overturning Circulation (AMOC) during the late Pliocene, proposed as a possible mechanism based on ocean core records of δ13C, also is not present in the model simulations. Here, we present CESM simulations using a new reconstruction of late Pliocene paleogeography that has the Bering Strait (BS) and Canadian Arctic Archipelago (CAA) Straits closed. We find that the closure of these small Arctic gateways strengthens the AMOC, by inhibiting freshwater (FW) transport from the Pacific to the Arctic Ocean and from the Arctic Ocean to the Labrador Sea, leading to warmer sea surface temperatures in the North Atlantic. The cutoff of the short export route through the CAA results in a more saline Labrador and south Greenland Sea with increased deep convection. At the same time, as all FW now leaves the Arctic east of Greenland, there is a freshening of and decreased deepwater formation in the Norwegian Sea. Overall, the AMOC strengthens. This past time period has implications for a future Earth under more responsible scenarios of emissions. Late Pliocene atmospheric carbon dioxide concentrations are estimated to have ranged between 350 and 450 ppmv and the paleogeography is relatively similar to modern. Our study indicates that the state of the Arctic gateways may influence the sensitivity of the North Atlantic climate in complex ways, and better understanding of the

The influence of physical factors on kelp and sea urchin distribution in previously and still grazed areas in the NE Atlantic.

Directory of Open Access Journals (Sweden)

Eli Rinde

Full Text Available The spatial distribution of kelp (Laminaria hyperborea and sea urchins (Strongylocentrotus droebachiensis in the NE Atlantic are highly related to physical factors and to temporal changes in temperature. On a large scale, we identified borders for kelp recovery and sea urchin persistence along the north-south gradient. Sea urchin persistence was also related to the coast-ocean gradient. The southern border corresponds to summer temperatures exceeding about 10°C, a threshold value known to be critical for sea urchin recruitment and development. The outer border along the coast-ocean gradient is related to temperature, wave exposure and salinity. On a finer scale, kelp recovery occurs mainly at ridges in outer, wave exposed, saline and warm areas whereas sea urchins still dominate in inner, shallow and cold areas, particularly in areas with optimal current speed for sea urchin foraging. In contrast to other studies in Europe, we here show a positive influence of climate change to presence of a long-lived climax canopy-forming kelp. The extent of the coast-ocean gradient varies within the study area, and is especially wide in the southern part where the presence of islands and skerries increases the area of the shallow coastal zone. This creates a large area with intermediate physical conditions for the two species and a mosaic of kelp and sea urchin dominated patches. The statistical models (GAM and BRT show high performance and indicate recovery of kelp in 45-60% of the study area. The study shows the value of combining a traditional (GAM and a more complex (BRT modeling approach to gain insight into complex spatial patterns of species or habitats. The results, methods and approaches are of general ecological relevance regardless of ecosystems and species, although they are particularly relevant for understanding and exploring the corresponding changes between algae and grazers in different coastal areas.

The influence of physical factors on kelp and sea urchin distribution in previously and still grazed areas in the NE Atlantic.

Science.gov (United States)

Rinde, Eli; Christie, Hartvig; Fagerli, Camilla W; Bekkby, Trine; Gundersen, Hege; Norderhaug, Kjell Magnus; Hjermann, Dag Ø

2014-01-01

The spatial distribution of kelp (Laminaria hyperborea) and sea urchins (Strongylocentrotus droebachiensis) in the NE Atlantic are highly related to physical factors and to temporal changes in temperature. On a large scale, we identified borders for kelp recovery and sea urchin persistence along the north-south gradient. Sea urchin persistence was also related to the coast-ocean gradient. The southern border corresponds to summer temperatures exceeding about 10°C, a threshold value known to be critical for sea urchin recruitment and development. The outer border along the coast-ocean gradient is related to temperature, wave exposure and salinity. On a finer scale, kelp recovery occurs mainly at ridges in outer, wave exposed, saline and warm areas whereas sea urchins still dominate in inner, shallow and cold areas, particularly in areas with optimal current speed for sea urchin foraging. In contrast to other studies in Europe, we here show a positive influence of climate change to presence of a long-lived climax canopy-forming kelp. The extent of the coast-ocean gradient varies within the study area, and is especially wide in the southern part where the presence of islands and skerries increases the area of the shallow coastal zone. This creates a large area with intermediate physical conditions for the two species and a mosaic of kelp and sea urchin dominated patches. The statistical models (GAM and BRT) show high performance and indicate recovery of kelp in 45-60% of the study area. The study shows the value of combining a traditional (GAM) and a more complex (BRT) modeling approach to gain insight into complex spatial patterns of species or habitats. The results, methods and approaches are of general ecological relevance regardless of ecosystems and species, although they are particularly relevant for understanding and exploring the corresponding changes between algae and grazers in different coastal areas.

Genetic diversity of the NE Atlantic sea urchin Strongylocentrotus droebachiensis unveils chaotic genetic patchiness possibly linked to local selective pressure.

Science.gov (United States)

Norderhaug, K M; Anglès d'Auriac, M B; Fagerli, C W; Gundersen, H; Christie, H; Dahl, K; Hobæk, A

We compared the genetic differentiation in the green sea urchin Strongylocentrotus droebachiensis from discrete populations on the NE Atlantic coast. By using eight recently developed microsatellite markers, genetic structure was compared between populations from the Danish Strait in the south to the Barents Sea in the north (56-79°N). Urchins are spread by pelagic larvae and may be transported long distances by northwards-going ocean currents. Two main superimposed patterns were identified. The first showed a subtle but significant genetic differentiation from the southernmost to the northernmost of the studied populations and could be explained by an isolation by distance model. The second pattern included two coastal populations in mid-Norway (65°N), NH and NS, as well as the northernmost population of continental Norway (71°N) FV. They showed a high degree of differentiation from all other populations. The explanation to the second pattern is most likely chaotic genetic patchiness caused by introgression from another species, S. pallidus, into S. droebachiensis resulting from selective pressure. Ongoing sea urchin collapse and kelp forests recovery are observed in the area of NH, NS and FV populations. High gene flow between populations spanning more than 22° in latitude suggests a high risk of new grazing events to occur rapidly in the future if conditions for sea urchins are favourable. On the other hand, the possibility of hybridization in association with collapsing populations may be used as an early warning indicator for monitoring purposes.

The carbon budget of the North Sea

NARCIS (Netherlands)

Thomas, H.; Bozec, Y.; Baar, H.J.W. de; Elkalay, K.; Frankignoulle, M.; Schiettecatte, L.-S.; Kattner, G.; Borges, A.V.; Gattuso, J.-P.

2005-01-01

A carbon budget has been established for the North Sea, a shelf sea on the NW European continental shelf. The carbon exchange fluxes with the North Atlantic Ocean dominate the gross carbon budget. The net carbon budget – more relevant to the issue of the contribution of the coastal ocean to the

Temperature profile and water depth data collected from USCGC HARRIOT LANE using BT and XBT casts in the Northwest Atlantic Ocean and Caribbean Sea from 30 April 1988 to 31 May 1988 (NODC Accession 8800173)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and water depth data were collected using BT and XBT casts from the USCGC HARRIOT LANE in the Northwest Atlantic Ocean and Caribbean Sea. Data...

ON THE INFLUENCE OF GLOBAL WARMING ON ATLANTIC HURRICANE FREQUENCY

Directory of Open Access Journals (Sweden)

S. R. Hosseini

2018-04-01

Full Text Available In this paper, the possible connection between the frequency of Atlantic hurricanes to the climate change, mainly the variation in the Atlantic Ocean surface temperature has been investigated. The correlation between the observed hurricane frequency for different categories of hurricane’s intensity and Sea Surface Temperature (SST has been examined over the Atlantic Tropical Cyclogenesis Regions (ACR. The results suggest that in general, the frequency of hurricanes have a high correlation with SST. In particular, the frequency of extreme hurricanes with Category 5 intensity has the highest correlation coefficient (R = 0.82. In overall, the analyses in this work demonstrates the influence of the climate change condition on the Atlantic hurricanes and suggest a strong correlation between the frequency of extreme hurricanes and SST in the ACR.

The imprint of anthropogenic CO2 emissions on Atlantic bluefin tuna otoliths

Science.gov (United States)

Fraile, Igaratza; Arrizabalaga, Haritz; Groeneveld, Jeroen; Kölling, Martin; Santos, Miguel Neves; Macías, David; Addis, Piero; Dettman, David L.; Karakulak, Saadet; Deguara, Simeon; Rooker, Jay R.

2016-06-01

Otoliths of Atlantic bluefin tuna (Thunnus thynnus) collected from the Mediterranean Sea and North Atlantic Ocean were analyzed to evaluate changes in the seawater isotopic composition over time. We report an annual otolith δ13C record that documents the magnitude of the δ13C depletion in the Mediterranean Sea between 1989 and 2010. Atlantic bluefin tuna in our sample (n = 632) ranged from 1 to 22 years, and otolith material corresponding to the first year of life (back-calculated birth year) was used to reconstruct seawater isotopic composition. Otolith δ18O remained relatively stable between 1989 and 2010, whereas a statistically significant decrease in δ13C was detected across the time interval investigated, with a rate of decline of 0.05‰ yr- 1 (- 0.94‰ depletion throughout the recorded period). The depletion in otolith δ13C over time was associated with the oceanic uptake of anthropogenically derived CO2.

Nitrous oxide and methane in the Atlantic Ocean between 50°N and 52°S: Latitudinal distribution and sea-to-air flux

Science.gov (United States)

Forster, Grant; Upstill-Goddard, Rob C.; Gist, Niki; Robinson, Carol; Uher, Gunther; Woodward, E. Malcolm S.

2009-07-01

We discuss nitrous oxide (N 2O) and methane (CH 4) distributions in 49 vertical profiles covering the upper ˜300 m of the water column along two ˜13,500 km transects between ˜50°N and ˜52°S during the Atlantic Meridional Transect (AMT) programme (AMT cruises 12 and 13). Vertical N 2O profiles were amenable to analysis on the basis of common features coincident with Longhurst provinces. In contrast, CH 4 showed no such pattern. The most striking feature of the latitudinal depth distributions was a well-defined "plume" of exceptionally high N 2O concentrations coincident with very low levels of CH 4, located between ˜23.5°N and ˜23.5°S; this feature reflects the upwelling of deep waters containing N 2O derived from nitrification, as identified by an analysis of N 2O, apparent oxygen utilization (AOU) and NO 3-, and presumably depleted in CH 4 by bacterial oxidation. Sea-to-air emissions fluxes for a region equivalent to ˜42% of the Atlantic Ocean surface area were in the range 0.40-0.68 Tg N 2O yr -1 and 0.81-1.43 Tg CH 4 yr -1. Based on contemporary estimates of the global ocean source strengths of atmospheric N 2O and CH 4, the Atlantic Ocean could account for ˜6-15% and 4-13%, respectively, of these source totals. Given that the Atlantic Ocean accounts for around 20% of the global ocean surface, on unit area basis it appears that the Atlantic may be a slightly weaker source of atmospheric N 2O than other ocean regions but it could make a somewhat larger contribution to marine-derived atmospheric CH 4 than previously thought.

Growth studies on Norway lobster, Nephrops norvegicus (L., in different areas of the Mediterranean Sea and the adjacent Atlantic

Directory of Open Access Journals (Sweden)

Chryssi Mytilineou

1998-12-01

Full Text Available A comparative study of the growth of Nephrops norvegicus among different areas in the Mediterranean Sea and the adjacent Atlantic was conducted. MIX and Bhattacharya´s length-based methods were used for age determination. Both methods were used for all the studied areas. For the estimation of the growth parameters two non-linear methods, based on the results of the length frequency analysis, were used; the Gauss-Newton method, implemented by the SAS program, was applied using the results of the MIX and the FISHPARM program using the results of the Bhattacharya´s method. The identification of the age groups and their mean lengths-at-age as well as the estimation of the growth parameters proved to be difficult. A question regarding the adequacy of the von Bertalanffy model was also posed. Remarkable differences were obvious between sexes in the number of identified age groups and their mean lengths-at-age as well as in their growth parameters in all areas. The comparison of the results obtained for the studied areas showed differences, which could not be considered very important except in the case of the Nephrops population of the Alboran Sea, which was characterised by a high growth rate. All other areas seemed to be close; among them the populations from Euboikos Gulf and Catalan Sea being the most different.

Enhanced biennial variability in the Pacific due to Atlantic capacitor effect.

Science.gov (United States)

Wang, Lei; Yu, Jin-Yi; Paek, Houk

2017-03-20

The El Niño-Southern Oscillation (ENSO) and the variability in the Pacific subtropical highs (PSHs) have major impacts on social and ecological systems. Here we present an Atlantic capacitor effect mechanism to suggest that the Atlantic is a key pacemaker of the biennial variability in the Pacific including that in ENSO and the PSHs during recent decades. The 'charging' (that is, ENSO imprinting the North Tropical Atlantic (NTA) sea surface temperature (SST) via an atmospheric bridge mechanism) and 'discharging' (that is, the NTA SST triggering the following ENSO via a subtropical teleconnection mechanism) processes alternate, generating the biennial rhythmic changes in the Pacific. Since the early 1990s, a warmer Atlantic due to the positive phase of Atlantic multidecadal oscillation and global warming trend has provided more favourable background state for the Atlantic capacitor effect, giving rise to enhanced biennial variability in the Pacific that may increase the occurrence frequency of severe natural hazard events.

Atlantic Ocean CARINA data: overview and salinity adjustments

Directory of Open Access Journals (Sweden)

T. Tanhua

2010-02-01

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

The air-sea exchange of mercury in the low latitude Pacific and Atlantic Oceans

Science.gov (United States)

Mason, Robert P.; Hammerschmidt, Chad R.; Lamborg, Carl H.; Bowman, Katlin L.; Swarr, Gretchen J.; Shelley, Rachel U.

2017-04-01

Air-sea exchange is an important component of the global mercury (Hg) cycle as it mediates the rate of increase in ocean Hg, and therefore the rate of change in levels of methylmercury (MeHg), the most toxic and bioaccumulative form of Hg in seafood and the driver of human health concerns. Gas evasion of elemental Hg (Hg0) from the ocean is an important sink for ocean Hg with previous studies suggesting that evasion is not uniform across ocean basins. To understand further the factors controlling Hg0 evasion, and its relationship to atmospheric Hg deposition, we made measurements of dissolved Hg0 (DHg0) in surface waters, along with measurements of Hg in precipitation and on aerosols, and Hg0 in marine air, during two GEOTRACES cruises; GP16 in the equatorial South Pacific and GA03 in the North Atlantic. We contrast the concentrations and estimated evasion fluxes of Hg0 during these cruises, and the factors influencing this exchange. Concentrations of DHg0 and fluxes were lower during the GP16 cruise than during the GA03 cruise, and likely reflect the lower atmospheric deposition in the South Pacific. An examination of Hg/Al ratios for aerosols from the cruises suggests that they were anthropogenically-enriched relative to crustal material, although to a lesser degree for the South Pacific than the aerosols over the North Atlantic. Both regions appear to be net sources of Hg0 to the atmosphere (evasion>deposition) and the reasons for this are discussed. Overall, the studies reported here provide further clarification on the factors controlling evasion of Hg0 from the ocean surface, and the role of anthropogenic inputs in influencing ocean Hg concentrations.

Bathymetric and geographic population structure in the pan-Atlantic deep-sea bivalve Deminucula atacellana (Schenck, 1939).

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Zardus, John D; Etter, Ron J; Chase, Michael R; Rex, Michael A; Boyle, Elizabeth E

2006-03-01

The deep-sea soft-sediment environment hosts a diverse and highly endemic fauna of uncertain origin. We know little about how this fauna evolved because geographic patterns of genetic variation, the essential information for inferring patterns of population differentiation and speciation are poorly understood. Using formalin-fixed specimens from archival collections, we quantify patterns of genetic variation in the protobranch bivalve Deminucula atacellana, a species widespread throughout the Atlantic Ocean at bathyal and abyssal depths. Samples were taken from 18 localities in the North American, West European and Argentine basins. A hypervariable region of mitochondrial 16S rDNA was amplified by polymerase chain reaction (PCR) and sequenced from 130 individuals revealing 21 haplotypes. Except for several important exceptions, haplotypes are unique to each basin. Overall gene diversity is high (h = 0.73) with pronounced population structure (Phi(ST) = 0.877) and highly significant geographic associations (P < 0.0001). Sequences cluster into four major clades corresponding to differences in geography and depth. Genetic divergence was much greater among populations at different depths within the same basin, than among those at similar depths but separated by thousands of kilometres. Isolation by distance probably explains much of the interbasin variation. Depth-related divergence may reflect historical patterns of colonization or strong environmental selective gradients. Broadly distributed deep-sea organisms can possess highly genetically divergent populations, despite the lack of any morphological divergence.

Mechanisms of long-term mean sea level variability in the North Sea

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Dangendorf, Sönke; Calafat, Francisco; Øie Nilsen, Jan Even; Richter, Kristin; Jensen, Jürgen

2015-04-01

We examine mean sea level (MSL) variations in the North Sea on timescales ranging from months to decades under the consideration of different forcing factors since the late 19th century. We use multiple linear regression models, which are validated for the second half of the 20th century against the output of a state-of-the-art tide+surge model (HAMSOM), to determine the barotropic response of the ocean to fluctuations in atmospheric forcing. We demonstrate that local atmospheric forcing mainly triggers MSL variability on timescales up to a few years, with the inverted barometric effect dominating the variability along the UK and Norwegian coastlines and wind (piling up the water along the coast) controlling the MSL variability in the south from Belgium up to Denmark. However, in addition to the large inter-annual sea level variability there is also a considerable fraction of decadal scale variability. We show that on decadal timescales MSL variability in the North Sea mainly reflects steric changes, which are mostly remotely forced. A spatial correlation analysis of altimetry observations and baroclinic ocean model outputs suggests evidence for a coherent signal extending from the Norwegian shelf down to the Canary Islands. This supports the theory of longshore wind forcing along the eastern boundary of the North Atlantic causing coastally trapped waves to propagate along the continental slope. With a combination of oceanographic and meteorological measurements we demonstrate that ~80% of the decadal sea level variability in the North Sea can be explained as response of the ocean to longshore wind forcing, including boundary wave propagation in the Northeast Atlantic. These findings have important implications for (i) detecting significant accelerations in North Sea MSL, (ii) the conceptual set up of regional ocean models in terms of resolution and boundary conditions, and (iii) the development of adequate and realistic regional climate change projections.

CURRENT STATE OF FISHERIES AND ASSESSMENT OF FISH STOCKS IN THE WESTERN MIDDLE OF THE CASPIAN SEA. PROSPECTS FOR THE USE OF THE FISH RESOURCES

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A. S. Abdusamadov

2016-01-01

Full Text Available Aim. To aim is to assess stocks and the fisheries of aquatic biological resources in the western part of the middle Caspian Sea and perspectives for the use of their resource potential.Methods. On the basis of the literature sources and our own data on the fish inventory in the western part of the Middle Caspian, we discuss possible reasons for emerging environmental, economic and other problems in the use of biological resources.Results. The main negative factors are the large-scale poaching, resulting in a catastrophic reduction in stocks of sturgeon and other valuable fish species of the Caspian Sea, a natural penetration of alien organisms (Mnemiopsis and overfishing of some species. The potential danger is large-scale development of oil and gas fields in the Caspian Sea, which can lead to even worse situation for the biological resources of the sea.Conclusions. In order to preserve the biological resources of the sea it is necessary to create conditions for steadily developing fishing and fish processing enterprises, thus ensuring the satisfaction of the constant demand for fish products and an increase in the revenue base of the budget and the well-being of the Russian population.

The wind sea and swell waves climate in the Nordic seas

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Semedo, Alvaro; Vettor, Roberto; Breivik, Øyvind; Sterl, Andreas; Reistad, Magnar; Soares, Carlos Guedes; Lima, Daniela

2015-02-01

A detailed climatology of wind sea and swell waves in the Nordic Seas (North Sea, Norwegian Sea, and Barents Sea), based on the high-resolution reanalysis NORA10, developed by the Norwegian Meteorological Institute, is presented. The higher resolution of the wind forcing fields, and the wave model (10 km in both cases), along with the inclusion of the bottom effect, allowed a better description of the wind sea and swell features, compared to previous global studies. The spatial patterns of the swell-dominated regional wave fields are shown to be different from the open ocean, due to coastal geometry, fetch dimensions, and island sheltering. Nevertheless, swell waves are still more prevalent and carry more energy in the Nordic Seas, with the exception of the North Sea. The influence of the North Atlantic Oscillation on the winter regional wind sea and swell patterns is also presented. The analysis of the decadal trends of wind sea and swell heights during the NORA10 period (1958-2001) shows that the long-term trends of the total significant wave height (SWH) in the Nordic Seas are mostly due to swell and to the wave propagation effect.

Temporal and Spatial Scales of Labrador Sea Water Formation

Science.gov (United States)

Clarke, R. A.

1984-01-01

Labrador Sea Water is an intermediate water found at the same density and depth range in the North Atlantic as the Mediterranean water. It is formed by convection from the sea surface to depths greather than 2 km in winter in the Western Labrador Sea. The processes leading to deep convection begin with the formation of a 200 km scale cyclonic circulation about denser than average upper layer water in the Western Labrador Sea. This circulation pattern is hypothesized to be driven by an ocean/atmosphere heat exchange that has its maximum in this region. By early March, if deep convection is taking place, one sees that this body of denser upper waters penetrates to the top of the deep temperature/salinity maximum marking the core of the North Atlantic Deep Water. We note that the horizontal scale of this body is still 100-200 km normal to the coastline.

Temperature profile and water depth data collected from USS JOHN RODGERS using BT and XBT casts in the NE/NW Atlantic Ocean and other seas from 03 August 1988 to 03 October 1988 (NODC Accession 8900041)

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National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and water depth data were collected using BT and XBT casts from the USS JOHN RODGERS in the Northeast / Northwest Atlantic Ocean, Ionian Sea,...

Plastic pollution in islands of the Atlantic Ocean.

Science.gov (United States)

Monteiro, Raqueline C P; Ivar do Sul, Juliana A; Costa, Monica F

2018-07-01

Marine plastic pollution is present in all oceans, including remote oceanic islands. Despite the increasing number of articles on plastic pollution in the last years, there is still a lack of studies in islands, that are biodiversity hotspots when compared to the surrounding ocean, and even other recognized highly biodiverse marine environments. Articles published in the peer reviewed literature (N = 20) were analysed according to the presence of macro (>5 mm) and microplastics (plastics associated with variables such as position of the beach in relation to wind and currents. Very few studies have analysed plastics colonization by organisms or the identification of persistent organic pollutants (POPs). Islands of the North/South Atlantic and Caribbean Sea were influenced by different sources of macroplastics, being marine-based sources (i.e., fishing activities) predominant in the Atlantic Ocean basin. On the other hand, in the Caribbean Sea, land-based sources were more common. Copyright © 2018 Elsevier Ltd. All rights reserved.

Revision of Chone Krøyer, 1856 (Polychaeta: Sabellidae from the eastern central Atlantic and Mediterranean Sea with descriptions of two new species

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María Ana Tovar-Hernández

2007-06-01

Full Text Available A neotype specimen is designated for Chone acustica (Claparède, 1870 with a full description. The original descriptions of Chone arenicola Langerhans, 1880 and Chone collaris Langerhans, 1880, both from Madeira, did not include some details and incomplete or misleading information was provided, so both species are redescribed. Amendments to the description of Chone longiseta Giangrande, 1992 are also given together with the methyl green staining pattern of Chone usticensis Giangrande et al. 2006. Two new species are described: Chone gambiae sp. nov., from the Gulf of Naples and Chone dunerificta sp. nov., from the Gulf of Salerno. This study shows the distribution of Chone duneri Krøyer, 1856, and Chone filicaudata Southern, 1914, to be restricted to the Arctic seas and North Atlantic Ocean, respectively. Records from the Mediterranean Sea are found to be erroneous.

Deglacial and Holocene sea-ice variability north of Iceland and response to ocean circulation changes

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Xiao, Xiaotong; Zhao, Meixun; Knudsen, Karen Luise; Sha, Longbin; Eiríksson, Jón; Gudmundsdóttir, Esther; Jiang, Hui; Guo, Zhigang

2017-08-01

Sea-ice conditions on the North Icelandic shelf constitute a key component for the study of the climatic gradients between the Arctic and the North Atlantic Oceans at the Polar Front between the cold East Icelandic Current delivering Polar surface water and the relatively warm Irminger Current derived from the North Atlantic Current. The variability of sea ice contributes to heat reduction (albedo) and gas exchange between the ocean and the atmosphere, and further affects the deep-water formation. However, lack of long-term and high-resolution sea-ice records in the region hinders the understanding of palaeoceanographic change mechanisms during the last glacial-interglacial cycle. Here, we present a sea-ice record back to 15 ka (cal. ka BP) based on the sea-ice biomarker IP25, phytoplankton biomarker brassicasterol and terrestrial biomarker long-chain n-alkanols in piston core MD99-2272 from the North Icelandic shelf. During the Bølling/Allerød (14.7-12.9 ka), the North Icelandic shelf was characterized by extensive spring sea-ice cover linked to reduced flow of warm Atlantic Water and dominant Polar water influence, as well as strong meltwater input in the area. This pattern showed an anti-phase relationship with the ice-free/less ice conditions in marginal areas of the eastern Nordic Seas, where the Atlantic Water inflow was strong, and contributed to an enhanced deep-water formation. Prolonged sea-ice cover with occasional occurrence of seasonal sea ice prevailed during the Younger Dryas (12.9-11.7 ka) interrupted by a brief interval of enhanced Irminger Current and deposition of the Vedde Ash, as opposed to abruptly increased sea-ice conditions in the eastern Nordic Seas. The seasonal sea ice decreased gradually from the Younger Dryas to the onset of the Holocene corresponding to increasing insolation. Ice-free conditions and sea surface warming were observed for the Early Holocene, followed by expansion of sea ice during the Mid-Holocene.

Environmental radioactivity in the North Atlantic region. The Faroe Islands and Greenland included. 1983

International Nuclear Information System (INIS)

Aarkrog, A.; Boelskifte, S.; Buch, E.; Christensen, G.C.; Dahlgaard, H.; Hallstadius, L.; Hansen, H.; Holm, E.; Mattsson, S.; Meide, A.

1984-12-01

Measurements of fallout radioactivity in the North Atlantic region including the Faroe Islands and Greenland are reported. Strontium-90 and cesium-137 was determined in samples of precipitation, sea water, vegetation, various foodstuffs (including milk in the Faroes) and drinking water. Estimates are given of the mean contents of 90 Sr and 137 Cs in human diet in the Faroes and Greenland in 1983. Results from samplings of surface sea water and seaweed in the Norwegian and Greenland Seas and along the Norwegian and Greenland west coasts are reported. Beside radiocesium and 90 Sr some of these samples have also been anlysed for tritium,plutonium and americium. Finally technetium-99 data on seaweed samples collected in the North Atlantic region since the beginning of the sixties are presented. (author)

Environmental radioactivity in the North Atlantic region. The Faroe Islands and Greenland included. 1984

International Nuclear Information System (INIS)

Aarkrog, A.; Boelskifte, S.; Buch, E.; Christensen, G.C.; Dahlgaard, H.; Hallstadius, L.; Hansen, H.; Holm, E.

1985-12-01

Measurements of fallout radioactivity in the North Atlantic region including the Faroe Islands and Greenland are reported. Strontium-90 and cesium-137 was determined in samples of precipitation, sea water, vegetation, various foodstuffs (including milk in the Faroes) and drinking water. Estimates are given of the mean contents of 90 Sr and 137 Cs in human diet in the Faroes and Greenland in 1984. Results from samplings of surface sea water and seaweed in the Norwegian and Greenland Seas and along the Norwegian and Greenland west coasts are reported. Beside radiocesium and 90 Sr some of these samples have also been anlysed for tritium, polonium, plutonium and americium. Finally technetium-99 data on seaweed samples collected in the North Atlantic region since the beginning of the sixties are presented. (author)

Environmental radioactivity in the North Atlantic region. The Faroe Islands and Greenland included. 1985

International Nuclear Information System (INIS)

Aarkrog, A.; Boelskifte, S.; Dahlgaard, H.; Hansen, H.; Buch, E.; Christensen, G.C.; Hallstadius, L.; Rioseco, J.; Holm, E.

1987-06-01

Measurements of fallout radioactivity in the North Atlantic region including the Faroe Islands and Greenland are reported. Strontium-90 and cesium-137 was determined in samples of precipitation, sea water vegetation, various foodstuffs (including milk in the Faroes) and drinking water. Estimates are given of the mean contents of 90 Sr a 137 Cs in human diet in the Faroes and Greenland in 1985. Results from samplings of surface sea water and seaweed in the English Channel, the Fram Strait and along the Norwegian and Greenland coast are reported. Beside radiocesium and 90 Sr some of these samples have also been analysed for tritium, plutonium and americium. Finally technetium-99 data on seaweed and sea water samples collected in the North Atlantic region are presented. 14 refs. (author)

Partial pressure (or fugacity) of carbon dioxide, dissolved inorganic carbon, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the JOHAN HJORT in the North Atlantic Ocean, North Greenland Sea and Norwegian Sea from 1992-07-12 to 1992-07-28 (NODC Accession 0113558)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113558 includes chemical, discrete sample, physical and profile data collected from JOHAN HJORT in the North Atlantic Ocean, North Greenland Sea and...

Partial pressure (or fugacity) of carbon dioxide, dissolved inorganic carbon, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the JOHAN HJORT in the North Atlantic Ocean, North Greenland Sea and Norwegian Sea from 1994-07-23 to 1994-08-16 (NODC Accession 0113560)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113560 includes chemical, discrete sample, physical and profile data collected from JOHAN HJORT in the North Atlantic Ocean, North Greenland Sea and...

Pronounced centennial-scale Atlantic Ocean climate variability correlated with Western Hemisphere hydroclimate

Science.gov (United States)

Thirumalai, Kaustubh; Quinn, Terrence M.; Okumura, Yuko; Richey, Julie; Partin, Judson W.; Poore, Richard Z.; Moreno-Chamarro, Eduardo

2018-01-01

Surface-ocean circulation in the northern Atlantic Ocean influences Northern Hemisphere climate. Century-scale circulation variability in the Atlantic Ocean, however, is poorly constrained due to insufficiently-resolved paleoceanographic records. Here we present a replicated reconstruction of sea-surface temperature and salinity from a site sensitive to North Atlantic circulation in the Gulf of Mexico which reveals pronounced centennial-scale variability over the late Holocene. We find significant correlations on these timescales between salinity changes in the Atlantic, a diagnostic parameter of circulation, and widespread precipitation anomalies using three approaches: multiproxy synthesis, observational datasets, and a transient simulation. Our results demonstrate links between centennial changes in northern Atlantic surface-circulation and hydroclimate changes in the adjacent continents over the late Holocene. Notably, our findings reveal that weakened surface-circulation in the Atlantic Ocean was concomitant with well-documented rainfall anomalies in the Western Hemisphere during the Little Ice Age.

Pronounced centennial-scale Atlantic Ocean climate variability correlated with Western Hemisphere hydroclimate.

Science.gov (United States)

Thirumalai, Kaustubh; Quinn, Terrence M; Okumura, Yuko; Richey, Julie N; Partin, Judson W; Poore, Richard Z; Moreno-Chamarro, Eduardo

2018-01-26

Surface-ocean circulation in the northern Atlantic Ocean influences Northern Hemisphere climate. Century-scale circulation variability in the Atlantic Ocean, however, is poorly constrained due to insufficiently-resolved paleoceanographic records. Here we present a replicated reconstruction of sea-surface temperature and salinity from a site sensitive to North Atlantic circulation in the Gulf of Mexico which reveals pronounced centennial-scale variability over the late Holocene. We find significant correlations on these timescales between salinity changes in the Atlantic, a diagnostic parameter of circulation, and widespread precipitation anomalies using three approaches: multiproxy synthesis, observational datasets, and a transient simulation. Our results demonstrate links between centennial changes in northern Atlantic surface-circulation and hydroclimate changes in the adjacent continents over the late Holocene. Notably, our findings reveal that weakened surface-circulation in the Atlantic Ocean was concomitant with well-documented rainfall anomalies in the Western Hemisphere during the Little Ice Age.

Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from Atlantic Companion in the Inner Sea - West Coast Scotland, Irish Sea and St. George's Channel and others from 2012-03-17 to 2012-12-06 (NCEI Accession 0157280)

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National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0157280 includes Surface underway, chemical, meteorological and physical data collected from Atlantic Companion in the Inner Sea - West Coast...

First insights into genus level diversity and biogeography of deep sea benthopelagic calanoid copepods in the South Atlantic and Southern Ocean

Science.gov (United States)

Renz, Jasmin; Markhaseva, Elena L.

2015-11-01

Calanoid copepods constitute the most numerous organisms not only in the pelagic realm, but also in the benthic boundary layer, which gives them an important role in the turnover of organic matter in the benthopelagic habitat. During seven expeditions to the South Atlantic and Southern Ocean, the diversity and biogeography of deep-sea benthopelagic calanoid copepods were studied. The communities of calanoids living in the vicinity of the seabed were characterized by high diversity comparable to many pelagic habitats, but low abundance of individuals. Members of the taxon Clausocalanoidea dominated the communities, and within this taxon most individuals belonged to detritivore calanoids characterized by sensory setae on the second maxillae or aetideid copepods. 73% of all genera classified as obligate or predominantly benthopelagic copepods detected during these expeditions were new to science and a vast number of genera and species have been described since then. Comparing the communities of calanoid genera between different regions, the assemblages in the Southern Ocean differed significantly from the Southeast and Southwest Atlantic. A latitudinal diversity gradient could be observed, with highest numbers of genera in the Southwest Atlantic and low numbers at stations in the Southern Ocean. Reviewing the literature, endemism for benthopelagic calanoids appeared to be low on a latitudinal range caused by connectivity in benthopelagic habitats through spreading water masses. However, considering the habitats structuring the water column vertically, a high number of genera are endemic in the benthopelagial and specialized to living within the vicinity of the seabed.

Western tropical Pacific multidecadal variability forced by the Atlantic multidecadal oscillation

Science.gov (United States)

Kucharski, F.; Sun, C.; Li, J.; Jin, F. F.; Kang, I. S.; Ding, R.

2017-12-01

Observational analysis suggests that the western tropical Pacific (WTP) sea surface temperature (SST) shows predominant variability over multidecadal time scales, which is unlikely to be explained by the Interdecadal Pacific Oscillation. Here we show that this variability is largely explained by the remote Atlantic multidecadal oscillation (AMO). A suite of Atlantic Pacemaker experiments successfully reproduces the WTP multidecadal variability and the AMO-WTP SST connection. The AMO warm SST anomaly generates an atmospheric teleconnection to the North Pacific, which weakens the Aleutian low and subtropical North Pacific westerlies. The wind changes induce a subtropical North Pacific SST warming through wind-evaporation-SST effect, and in response to this warming, the surface winds converge towards the subtropical North Pacific from the tropics, leading to anomalous cyclonic circulation and low pressure over the WTP region. The warm SST anomaly further develops due to the SST-sea level pressure-cloud-longwave radiation positive feedback. Our findings suggest that the Atlantic Ocean acts as a key pacemaker for the western Pacific decadal climate variability.

Air-sea exchange of carbon dioxide

Energy Technology Data Exchange (ETDEWEB)

Bakker, D C.E.; De Baar, H J.W.; De Jong, E; Koning, F A [Netherlands Institute for Sea Research NIOZ, Den Burg Texel (Netherlands)

1996-12-31

The greenhouse gas carbon dioxide is emitted by anthropogenic activities. The oceans presumably serve as a net sink for 17 to 39% of these emissions. The objective of this project is to quantify more accurately the locality, seasonality and magnitude of the net air-sea flux of CO2 with emphasis on the South Atlantic Ocean. In situ measurements of the fugacity of CO2 in surface water and marine air, of total dissolved inorganic carbon, alkalinity and of air-sea exchange of CO2 have been made at four Atlantic crossings, in the Southern Ocean, in a Norwegian fjord and in the Dutch coastal zone. Skin temperature was detected during several of the cruises. The data collected in the course of the project support and refine previous findings. Variability of dissolved CO2 in surface water is related in a complex way to biological and physical factors. The carbonate equilibria cause dissolved gaseous CO2 to react in an intricate manner to disturbances. Dissolved gaseous CO2 hardly ever attains equilibrium with the atmospheric CO2 content by means of air-sea exchange, before a new disturbance occurs. Surface water fCO2 changes could be separated in those caused by seasonal warming and those by biological uptake in a Southern Ocean spring. Incorporation of a thermal skin effect and a change of the wind speed interval strongly increased the small net oceanic uptake for the area. The Atlantic crossings point to a relationship between water mass history and surface water CO2 characteristics. In particular, current flow and related heat fluxes leave their imprint on the concentration dissolved gaseous CO2 and on air-sea exchange. In the Dutch coastal zone hydrography and inorganic carbon characteristics of the water were heterogeneous, which yielded variable air-sea exchange of CO2. figs., tabs., refs.

A model study of the seasonality of sea surface temperature and circulation in the Atlantic North-Eastern Tropical Upwelling System.

Directory of Open Access Journals (Sweden)

Saliou eFaye

2015-09-01

Full Text Available The climatological seasonal cycle of the sea surface temperature (SST in the north-eastern tropical Atlantic (7-25°N, 26-12°W is studied using a mixed layer heat budget in a regional ocean general circulation model. The region, which experiences one of the larger SST cycle in the tropics, forms the main part of the Guinea Gyre. It is characterized by a seasonally varying open ocean and coastal upwelling system, driven by the movements of the intertropical convergence zone (ITCZ. The model annual mean heat budget has two regimes schematically. South of roughly 12°N, advection of equatorial waters, mostly warm, and warming by vertical mixing, is balanced by net air-sea flux. In the rest of the domain, a cooling by vertical mixing, reinforced by advection at the coast, is balanced by the air-sea fluxes. Regarding the seasonal cycle, within a narrow continental band, in zonal mean, the SST early decrease (from September, depending on latitude, until December is driven by upwelling dynamics off Senegal and Mauritania (15°-20°N, and instead by air-sea fluxes north and south of these latitudes. Paradoxically, the later peaks of upwelling intensity (from March to July, with increasing latitude essentially damp the warming phase, driven by air-sea fluxes. The open ocean cycle to the west, is entirely driven by the seasonal net air-sea fluxes. The oceanic processes significantly oppose it, but for winter north of ~18°N. Vertical mixing in summer-autumn tends to cool (warm the surface north (south of the ITCZ, and advective cooling or warming by the geostrophic Guinea Gyre currents and the Ekman drift. This analysis supports previous findings on the importance of air-sea fluxes offshore. It mainly offers quantitative elements on the modulation of the SST seasonal cycle by the ocean circulation, and particularly by the upwelling dynamics.Keywords: SST, upwelling, circulation, heat budget, observations, modeling

North Atlantic variability and its links to European climate over the last 3000 years.

Science.gov (United States)

Moffa-Sánchez, Paola; Hall, Ian R

2017-11-23

The subpolar North Atlantic is a key location for the Earth's climate system. In the Labrador Sea, intense winter air-sea heat exchange drives the formation of deep waters and the surface circulation of warm waters around the subpolar gyre. This process therefore has the ability to modulate the oceanic northward heat transport. Recent studies reveal decadal variability in the formation of Labrador Sea Water. Yet, crucially, its longer-term history and links with European climate remain limited. Here we present new decadally resolved marine proxy reconstructions, which suggest weakened Labrador Sea Water formation and gyre strength with similar timing to the centennial cold periods recorded in terrestrial climate archives and historical records over the last 3000 years. These new data support that subpolar North Atlantic circulation changes, likely forced by increased southward flow of Arctic waters, contributed to modulating the climate of Europe with important societal impacts as revealed in European history.

Detection of emamectin benzoate tolerance emergence in different life stages of sea lice, Lepeophtheirus salmonis, on farmed Atlantic salmon, Salmo salar L.

Science.gov (United States)

Jones, P G; Hammell, K L; Gettinby, G; Revie, C W

2013-03-01

Emamectin benzoate has been used to treat sea lice, Lepeophtheirus salmonis, infestations on farmed Atlantic salmon, Salmo salar. Recent evidence suggests a reduction in effectiveness in some locations. A major challenge in the detection of tolerance emergence can be the typically low proportion of resistant individuals in a population during the early phases. The objectives of this study were to develop a method for determining differences in temporal development of tolerance between sea lice life stages and to explore how these differences might be used to improve the monitoring of treatment effectiveness in a clinical setting. This study examined two data sets based on records of sea lice abundance following emamectin benzoate treatments from the west coast of Scotland (2002-2006) and from New Brunswick, Canada (2004-2008). Life stages were categorized into two groups (adult females and the remaining mobile stages) to examine the trends in mean abundance and treatment effectiveness. Differences in emamectin benzoate effectiveness were found between the two groups by year and location, suggesting that an important part of monitoring drug resistance development in aquatic ectoparasites may be the need to focus on key life stages. © 2013 Blackwell Publishing Ltd.

Influence of North Atlantic modes on European climate extremes

Science.gov (United States)

Proemmel, K.; Cubasch, U.

2017-12-01

It is well known that the North Atlantic strongly influences European climate. Only few studies exist that focus on its impact on climate extremes. We are interested in these extremes and the processes and mechanisms behind it. For the analysis of the North Atlantic Oscillation (NAO) we use simulations performed with the Max Planck Institute for Meteorology Earth System Model (MPI-ESM). The NAO has a strong impact especially on European winter and the changes in minimum temperature are even larger than in maximum temperature. The impact of the Atlantic Multi-decadal Variability (AMV) on climate extremes is analyzed in ECHAM6 simulations forced with AMV warm and AMV cold sea surface temperature patterns. We analyze different extreme indices and try to understand the processes.

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.

Middle Holocene Organic Carbon and Biomarker Records from the South Yellow Sea: Relationship to the East Asian Monsoon

Science.gov (United States)

Zou, Liang; Hu, Bangqi; Li, Jun; Dou, Yanguang; Xie, Luhua; Dong, Liang

2018-03-01

The East Asian monsoon system influences the sedimentation and transport of organic matter in East Asian marginal seas that is derived from both terrestrial and marine sources. In this study, we determined organic carbon (OC) isotope values, concentrations of marine biomarkers, and levels of OC and total nitrogen (TN) in core YSC-1 from the central South Yellow Sea (SYS). Our objectives were to trace the sources of OC and variations in palaeoproductivity since the middle Holocene, and their relationships with the East Asian monsoon system. The relative contributions of terrestrial versus marine organic matter in core sediments were estimated using a two-end-member mixing model of OC isotopes. Results show that marine organic matter has been the main sediment constituent since the middle Holocene. The variation of terrestrial organic carbon concentration (OCter) is similar to the EASM history. However, the variation of marine organic carbon concentration (OCmar) is opposite to that of the EASM curve, suggesting OCmar is distinctly influenced by terrestrial material input. Inputs of terrestrial nutrients into the SYS occur in the form of fluvial and aeolian dust, while concentrations of nutrients in surface water are derived mainly from bottom water via the Yellow Sea circulation system, which is controlled by the East Asian winter monsoon (EAWM). Variations in palaeoproductivity represented by marine organic matter and biomarker records are, in general, consistent with the recent EAWM intensity studies, thus, compared with EASM, EAWM may play the main role to control the marine productivity variations in the SYS.

Variability along the Atlantic water pathway in the forced Norwegian Earth System Model

Science.gov (United States)

Langehaug, H. R.; Sandø, A. B.; Årthun, M.; Ilıcak, M.

2018-03-01

The growing attention on mechanisms that can provide predictability on interannual-to-decadal time scales, makes it necessary to identify how well climate models represent such mechanisms. In this study we use a high (0.25° horizontal grid) and a medium (1°) resolution version of a forced global ocean-sea ice model, utilising the Norwegian Earth System Model, to assess the impact of increased ocean resolution. Our target is the simulation of temperature and salinity anomalies along the pathway of warm Atlantic water in the subpolar North Atlantic and the Nordic Seas. Although the high resolution version has larger biases in general at the ocean surface, the poleward propagation of thermohaline anomalies is better resolved in this version, i.e., the time for an anomaly to travel northward is more similar to observation based estimates. The extent of these anomalies can be rather large in both model versions, as also seen in observations, e.g., stretching from Scotland to northern Norway. The easternmost branch into the Nordic and Barents Seas, carrying warm Atlantic water, is also improved by higher resolution, both in terms of mean heat transport and variability in thermohaline properties. A more detailed assessment of the link between the North Atlantic Ocean circulation and the thermohaline anomalies at the entrance of the Nordic Seas reveals that the high resolution is more consistent with mechanisms that are previously published. This suggests better dynamics and variability in the subpolar region and the Nordic Seas in the high resolution compared to the medium resolution. This is most likely due a better representation of the mean circulation in the studied region when using higher resolution. As the poleward propagation of ocean heat anomalies is considered to be a key source of climate predictability, we recommend that similar methodology presented herein should be performed on coupled climate models that are used for climate prediction.

WATER TEMPERATURE and other data from LEWIS B. PULLER, ELLIOT and USS DE WERT in the TOGA Area - Pacific, Caribbean Sea and NW Atlantic from 1986-11-07 to 1987-05-31 (NCEI Accession 9400029)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The data in this accession were collected in Caribbean Sea, NW Atlantic (limit-40 W), and TOGA Area - Pacific (30 N to 30 S) from ship ELLIOT, USS DE WERT, and LEWIS...

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.

Sea level rise in the Arctic Ocean

OpenAIRE

Proshutinsky, Andrey; Pavlov, Vladimir; Bourke, Robert H.

2001-01-01

The article of record as published may be found at http://dx.doi.org/10.1029/2000GL012760 About 60 tide-gauge stations in the Kara, Laptev, East-Siberian and Chukchi Seas have recorded the sea level change from the 1950s through 1990s. Over this 40-year period, most of these stations show a significant sea level rise (SLR). In light of global change, this SLR could be a manifestation of warming in the Artic coupled with a decrease of sea ice extent, warming of Atlantic waters, changes in...

Immunohistochemical localization of CYP1A, vitellogenin and Zona radiata proteins in the liver of swordfish (Xiphias gladius L.) taken from the Mediterranean Sea, South Atlantic, South Western Indian and Central North Pacific Oceans

International Nuclear Information System (INIS)

Desantis, S.; Corriero, A.; Cirillo, F.; Deflorio, M.; Brill, R.; Griffiths, M.; Lopata, A.L.; Serna, J.M. de la; Bridges, C.R.; Kime, D.E.; De Metrio, G.

2005-01-01

Cytochrome P4501A (CYP1A) monoxygenase, vitellogenin (Vtg) and Zona radiata proteins (Zrp) are frequently used as biomarkers of fish exposure to organic contaminants. In this work, swordfish liver sections obtained from the Mediterranean Sea, the South African coasts (South Atlantic and South Western Indian Oceans) and the Central North Pacific Ocean were immunostained with antisera against CYP1A, Zrp, and Vtg. CYP1A induction was found in hepatocytes, epithelium of the biliary ductus and the endothelium of large blood vessels of fish from the Mediterranean Sea and South African waters, but not from the Pacific Ocean. Zrp and Vtg were immunolocalized in hepatocytes of male swordfish from the Mediterranean Sea and from South African waters. Plasma Dot-Blot analysis, performed in Mediterranean and Pacific specimens, revealed the presence of Zrp and Vtg in males from Mediterranean but not from Pacific. These results confirm previous findings about the potential exposure of Mediterranean swordfish to endocrine, disrupting chemicals and raise questions concerning the possible presence of xenobiotic contaminants off the Southern coasts of South Africa in both the South Atlantic and South Western Indian Oceans

Pseudocollapse and rebuilding of North Sea mackerel (Scomber scombrus)

DEFF Research Database (Denmark)

Jansen, Teunis

2014-01-01

The largest observed change in mackerel (Scomber scombrus) abundance in the North Atlantic happened when the so-called “North Sea mackerel” collapsed due to overfishing. Despite protection, it has remained in a depleted state. Central to this interpretation was that the “North Sea mackerel...

The pollution of the North Sea

International Nuclear Information System (INIS)

1981-01-01

The subject is covered in chapters entitled: the North Sea and its rivers; the uses of the North Sea (shipping; exploitation of oil and gas; fishing; recreation; land reclamation; industrial islands; waste dumping); the nature of the dumping problem (nuclear waste; organic chemicals; inorganic chemicals; oil; sewage; rubble and dredged spoils; ash); pollution legislation; Greenpeace activities in the North Sea (the nuclear campaigns (Windscale; Cap de la Hague; Atlantic waste dumping); the chemical campaigns); what is needed in the future; references; the Oslo Convention. (U.K.)

Sea level rise and the geoid: factor analysis approach

OpenAIRE

Song, Hongzhi; Sadovski, Alexey; Jeffress, Gary

2013-01-01

Sea levels are rising around the world, and this is a particular concern along most of the coasts of the United States. A 1989 EPA report shows that sea levels rose 5-6 inches more than the global average along the Mid-Atlantic and Gulf Coasts in the last century. The main reason for this is coastal land subsidence. This sea level rise is considered more as relative sea level rise than global sea level rise. Thus, instead of studying sea level rise globally, this paper describes a statistical...

Early Eocene deep-sea benthic foraminiferal faunas: Recovery from the Paleocene Eocene Thermal Maximum extinction in a greenhouse world

Science.gov (United States)

Thomas, Ellen; D’haenens, Simon; Speijer, Robert P.; Alegret, Laia

2018-01-01

The early Eocene greenhouse world was marked by multiple transient hyperthermal events. The most extreme was the Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma), linked to the extinction of the globally recognised deep-sea benthic foraminiferal Velasco fauna, which led to the development of early Eocene assemblages. This turnover has been studied at high resolution, but faunal development into the later early Eocene is poorly documented. There is no widely accepted early Eocene equivalent of the Late Cretaceous-Paleocene Velasco fauna, mainly due to the use of different taxonomic concepts. We compiled Ypresian benthic foraminiferal data from 17 middle bathyal-lower abyssal ocean drilling sites in the Pacific, Atlantic and Indian Oceans, in order to characterise early Eocene deep-sea faunas by comparing assemblages across space, paleodepth and time. Nuttallides truempyi, Oridorsalis umbonatus, Bulimina trinitatensis, the Bulimina simplex group, the Anomalinoides spissiformis group, pleurostomellids, uniserial lagenids, stilostomellids and lenticulinids were ubiquitous during the early Eocene (lower-middle Ypresian). Aragonia aragonensis, the Globocassidulina subglobosa group, the Cibicidoides eocaenus group and polymorphinids became ubiquitous during the middle Ypresian. The most abundant early Ypresian taxa were tolerant to stressed or disturbed environments, either by opportunistic behavior (Quadrimorphina profunda, Tappanina selmensis, Siphogenerinoides brevispinosa) and/or the ability to calcify in carbonate-corrosive waters (N. truempyi). Nuttallides truempyi, T. selmensis and other buliminids (Bolivinoides cf. decoratus group, Bulimina virginiana) were markedly abundant during the middle Ypresian. Contrary to the long-lived, highly diverse and equitable Velasco fauna, common and abundant taxa reflect highly perturbed assemblages through the earliest Ypresian, with lower diversity and equitability following the PETM extinction. In contrast, the middle Ypresian

Early Eocene deep-sea benthic foraminiferal faunas: Recovery from the Paleocene Eocene Thermal Maximum extinction in a greenhouse world.

Directory of Open Access Journals (Sweden)

Gabriela J Arreguín-Rodríguez

Full Text Available The early Eocene greenhouse world was marked by multiple transient hyperthermal events. The most extreme was the Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma, linked to the extinction of the globally recognised deep-sea benthic foraminiferal Velasco fauna, which led to the development of early Eocene assemblages. This turnover has been studied at high resolution, but faunal development into the later early Eocene is poorly documented. There is no widely accepted early Eocene equivalent of the Late Cretaceous-Paleocene Velasco fauna, mainly due to the use of different taxonomic concepts. We compiled Ypresian benthic foraminiferal data from 17 middle bathyal-lower abyssal ocean drilling sites in the Pacific, Atlantic and Indian Oceans, in order to characterise early Eocene deep-sea faunas by comparing assemblages across space, paleodepth and time. Nuttallides truempyi, Oridorsalis umbonatus, Bulimina trinitatensis, the Bulimina simplex group, the Anomalinoides spissiformis group, pleurostomellids, uniserial lagenids, stilostomellids and lenticulinids were ubiquitous during the early Eocene (lower-middle Ypresian. Aragonia aragonensis, the Globocassidulina subglobosa group, the Cibicidoides eocaenus group and polymorphinids became ubiquitous during the middle Ypresian. The most abundant early Ypresian taxa were tolerant to stressed or disturbed environments, either by opportunistic behavior (Quadrimorphina profunda, Tappanina selmensis, Siphogenerinoides brevispinosa and/or the ability to calcify in carbonate-corrosive waters (N. truempyi. Nuttallides truempyi, T. selmensis and other buliminids (Bolivinoides cf. decoratus group, Bulimina virginiana were markedly abundant during the middle Ypresian. Contrary to the long-lived, highly diverse and equitable Velasco fauna, common and abundant taxa reflect highly perturbed assemblages through the earliest Ypresian, with lower diversity and equitability following the PETM extinction. In contrast, the

Early Eocene deep-sea benthic foraminiferal faunas: Recovery from the Paleocene Eocene Thermal Maximum extinction in a greenhouse world.

Science.gov (United States)

Arreguín-Rodríguez, Gabriela J; Thomas, Ellen; D'haenens, Simon; Speijer, Robert P; Alegret, Laia

2018-01-01

The early Eocene greenhouse world was marked by multiple transient hyperthermal events. The most extreme was the Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma), linked to the extinction of the globally recognised deep-sea benthic foraminiferal Velasco fauna, which led to the development of early Eocene assemblages. This turnover has been studied at high resolution, but faunal development into the later early Eocene is poorly documented. There is no widely accepted early Eocene equivalent of the Late Cretaceous-Paleocene Velasco fauna, mainly due to the use of different taxonomic concepts. We compiled Ypresian benthic foraminiferal data from 17 middle bathyal-lower abyssal ocean drilling sites in the Pacific, Atlantic and Indian Oceans, in order to characterise early Eocene deep-sea faunas by comparing assemblages across space, paleodepth and time. Nuttallides truempyi, Oridorsalis umbonatus, Bulimina trinitatensis, the Bulimina simplex group, the Anomalinoides spissiformis group, pleurostomellids, uniserial lagenids, stilostomellids and lenticulinids were ubiquitous during the early Eocene (lower-middle Ypresian). Aragonia aragonensis, the Globocassidulina subglobosa group, the Cibicidoides eocaenus group and polymorphinids became ubiquitous during the middle Ypresian. The most abundant early Ypresian taxa were tolerant to stressed or disturbed environments, either by opportunistic behavior (Quadrimorphina profunda, Tappanina selmensis, Siphogenerinoides brevispinosa) and/or the ability to calcify in carbonate-corrosive waters (N. truempyi). Nuttallides truempyi, T. selmensis and other buliminids (Bolivinoides cf. decoratus group, Bulimina virginiana) were markedly abundant during the middle Ypresian. Contrary to the long-lived, highly diverse and equitable Velasco fauna, common and abundant taxa reflect highly perturbed assemblages through the earliest Ypresian, with lower diversity and equitability following the PETM extinction. In contrast, the middle Ypresian

Nursery areas and recruitment variation of Northeast Atlantic mackerel (Scomber scombrus)

DEFF Research Database (Denmark)

Jansen, Teunis; Kristensen, Kasper; Van der Kooij, Jeroen

2015-01-01

There are currently no dedicated recruitment survey data available in support of the assessment of the abundance and distribution of Northeast Atlantic (NEA) mackerel (Scomber scombrus), one of the most widespread and commercially important fish stocks in the North Atlantic. This is despite the f......, showing that the most important nursery areas are around Ireland, north and west of Scotland, in the northern North Sea north of 598Nand, to some extent, also in the Bay of Biscay....

(Ceramiales, Rhodophyta) from the Canary Islands, eastern Atlantic

African Journals Online (AJOL)

The genus Osmundea is a strongly supported monophyletic group within the Laurencia complex and shows a disjunct distribution occurring in the North-East and South-West Pacific, the Indian and Atlantic oceans and the Mediterranean Sea. Its phenotypic plasticity on the Canary Islands may be the result of the high ...

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.

Temporal energy partitions of Florida extreme sea level events as a function of Atlantic multidecadal oscillation

Directory of Open Access Journals (Sweden)

J. Park

2010-06-01

Full Text Available An energy-conservative metric based on the discrete wavelet transform is applied to assess the relative energy distribution of extreme sea level events across different temporal scales. The metric is applied to coastal events at Key West and Pensacola Florida as a function of two Atlantic Multidecadal Oscillation (AMO regimes. Under AMO warm conditions there is a small but significant redistribution of event energy from nearly static into more dynamic (shorter duration timescales at Key West, while at Pensacola the AMO-dependent changes in temporal event behaviour are less pronounced. Extreme events with increased temporal dynamics might be consistent with an increase in total energy of event forcings which may be a reflection of more energetic storm events during AMO warm phases. As dynamical models mature to the point of providing regional climate index predictability, coastal planners may be able to consider such temporal change metrics in planning scenarios.

The establishment of Atlantic Water transport as a topographically trapped slope current off Scotland

Directory of Open Access Journals (Sweden)

Qin Zhou

2013-05-01

Full Text Available Atlantic Water, with its origin in the western Atlantic, enters the Nordic Seas partly as a barotropic current following the continental slope. This water mass is carried across the Atlantic by the baroclinic North Atlantic Current (NAC. When the NAC meets the continental slope at the east side of the Atlantic, some of the transport is converted to barotropic transport over the slope before continuing northward. Here, we show that this baroclinic to barotropic conversion is in agreement with geostrophic theory. Historical observations show that the transport of the slope current increases significantly from the Rockall Channel (RC to the Faroe–Shetland Channel (FSC. Geostrophy predicts that with a northward decreasing buoyancy, baroclinic currents from the west will be transferred into northward topographically steered barotropic flow. We use hydrographic data from two sections crossing the continental slope, one located in the RC and another in the FSC, to estimate baroclinic and barotropic transport changes over the slope, within the framework of geostrophic dynamics. Our results indicate that ~1 Sv of the cross-slope baroclinic flow is mainly converted to northward barotropic transport above the 200–500m isobaths, which is consistent with observed transport changes between the RC and the FSC. Similar processes are also likely to occur further south, along the eastern Atlantic margin. This shows that AW within the slope current in the FSC is derived from both the eastern and the western Atlantic, in agreement with earlier studies of AW inflow to the Nordic Seas.

Phylogeography of Rattus norvegicus in the South Atlantic Ocean

Directory of Open Access Journals (Sweden)

Melanie Hingston

2016-12-01

Full Text Available Norway rats are a globally distributed invasive species, which have colonized many islands around the world, including in the South Atlantic Ocean. We investigated the phylogeography of Norway rats across the South Atlantic Ocean and bordering continental countries. We identified haplotypes from 517 bp of the hypervariable region I of the mitochondrial D-loop and constructed a Bayesian consensus tree and median-joining network incorporating all other publicly available haplotypes via an alignment of 364 bp. Three Norway rat haplotypes are present across the islands of the South Atlantic Ocean, including multiple haplotypes separated by geographic barriers within island groups. All three haplotypes have been previously recorded from European countries. Our results support the hypothesis of rapid Norway rat colonization of South Atlantic Ocean islands by sea-faring European nations from multiple European ports of origin. This seems to have been the predominant pathway for repeated Norway rat invasions of islands, even within the same archipelago, rather than within-island dispersal across geographic barriers.

Warming shelf seas drive the subtropicalization of European pelagic fish communities.

Science.gov (United States)

Montero-Serra, Ignasi; Edwards, Martin; Genner, Martin J

2015-01-01

Pelagic fishes are among the most ecologically and economically important fish species in European seas. In principle, these pelagic fishes have potential to demonstrate rapid abundance and distribution shifts in response to climatic variability due to their high adult motility, planktonic larval stages, and low dependence on benthic habitat for food or shelter during their life histories. Here, we provide evidence of substantial climate-driven changes to the structure of pelagic fish communities in European shelf seas. We investigated the patterns of species-level change using catch records from 57,870 fisheries-independent survey trawls from across European continental shelf region between 1965 and 2012. We analysed changes in the distribution and rate of occurrence of the six most common species, and observed a strong subtropicalization of the North Sea and Baltic Sea assemblages. These areas have shifted away from cold-water assemblages typically characterized by Atlantic herring and European sprat from the 1960s to 1980s, to warmer-water assemblages including Atlantic mackerel, Atlantic horse mackerel, European pilchard and European anchovy from the 1990s onwards. We next investigated if warming sea temperatures have forced these changes using temporally comprehensive data from the North Sea region. Our models indicated the primary driver of change in these species has been sea surface temperatures in all cases. Together, these analyses highlight how individual species responses have combined to result in a dramatic subtropicalization of the pelagic fish assemblage of the European continental shelf. © 2014 John Wiley & Sons Ltd.

Evidence for an autumn downstream migration of Atlantic salmon Salmo salar (Linnaeus) and brown trout Salmo trutta (Linnaeus) parr to the Baltic Sea

Science.gov (United States)

Taal, Imre; Kesler, Martin; Saks, Lauri; Rohtla, Mehis; Verliin, Aare; Svirgsden, Roland; Jürgens, Kristiina; Vetemaa, Markus; Saat, Toomas

2014-06-01

In the eastern Baltic rivers, anadromous salmonid parr are known to smoltify and migrate to the sea from March until June, depending on latitude, climate and hydrological conditions. In this study, we present the first records of autumn descent of brown trout Salmo trutta and Atlantic salmon Salmo salar from the Baltic Sea Basin. Otolith microchemistry analyses revealed that these individuals hatched in freshwater and had migrated to the brackish water shortly prior to capture. The fish were collected in 2006, 2008, 2009 and 2013 from Eru Bay (surface salinity 4.5-6.5 ‰), Gulf of Finland. This relatively wide temporal range of observations indicates that the autumn descent of anadromous salmonids is not a random event. These results imply that autumn descent needs more consideration in the context of the effective stock management, assessment and restoration of Baltic salmonid populations and their habitats.

Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from METEOR in the Caribbean Sea and North Atlantic Ocean from 2004-07-10 to 2004-08-07 (NODC Accession 0116644)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0116644 includes chemical, discrete sample, physical and profile data collected from METEOR in the Caribbean Sea and North Atlantic Ocean from...

Tsunami Warning Services for the U.S. and Canadian Atlantic Coasts

Science.gov (United States)

Whitmore, P. M.; Knight, W.

2008-12-01

In January 2005, the National Oceanic and Atmospheric Administration (NOAA) developed a tsunami warning program for the U.S. Atlantic and Gulf of Mexico coasts. Within a year, this program extended further to the Atlantic coast of Canada and the Caribbean Sea. Warning services are provided to U.S. and Canadian coasts (including Puerto Rico and the Virgin Islands) by the NOAA/West Coast and Alaska Tsunami Warning Center (WCATWC) while the NOAA/Pacific Tsunami Warning Center (PTWC) provides services for non-U.S. entities in the Caribbean Basin. The Puerto Rico Seismic Network (PRSN) is also an active partner in the Caribbean Basin warning system. While the nature of the tsunami threat in the Atlantic Basin is different than in the Pacific, the warning system philosophy is similar. That is, initial messages are based strictly on seismic data so that information is provided to those at greatest risk as fast as possible while supplementary messages are refined with sea level observations and forecasts when possible. The Tsunami Warning Centers (TWCs) acquire regional seismic data through many agencies, such as the United States Geological Survey, Earthquakes Canada, regional seismic networks, and the PRSN. Seismic data quantity and quality are generally sufficient throughout most of the Atlantic area-of-responsibility to issue initial information within five minutes of origin time. Sea level data are mainly provided by the NOAA/National Ocean Service. Coastal tide gage coverage is generally denser along the Atlantic coast than in the Pacific. Seven deep ocean pressure sensors (DARTs), operated by the National Weather Service (NWS) National Data Buoy Center, are located in the Atlantic Basin (5 in the Atlantic Ocean, 1 in the Caribbean, and 1 in the Gulf of Mexico). The DARTs provide TWCs with the means to verify tsunami generation in the Atlantic and provide critical data with which to calibrate forecast models. Tsunami warning response criteria in the Atlantic Basin

South China Sea Wave Characteristics During Typhoon Muifa Passage in Winter 2004

National Research Council Canada - National Science Library

Chu, Peter C; Cheng, Kuo-Feng

2008-01-01

Ocean wave characteristics in the western Atlantic Ocean (Hurricane Region) to tropical cyclones have been investigated extensively, but not the regional seas in the western Pacific such as the South China Sea (Typhoon Region...

The Potential for Wave Energy in the North Sea

DEFF Research Database (Denmark)

Sørensen, H. C.; Chozas, Julia Fernandez

2010-01-01

The North Sea has not yet been regarded as prime area for wave energy development in Europe except in Denmark, Benelux and Germany. The reason is the relatively low intensity of waves (12-17kW/m) compared to the Atlantic with a wave climate of 24-48kW/m. Further on the design wave load is almost ...... is resulting in a prediction of a yearly production of 23TWh; the latter is estimating a yearly production of 77TWh. This equals to 6% of the electricity demand around the North Sea, where the annual electricity consumption is about 1,300TWh.......The North Sea has not yet been regarded as prime area for wave energy development in Europe except in Denmark, Benelux and Germany. The reason is the relatively low intensity of waves (12-17kW/m) compared to the Atlantic with a wave climate of 24-48kW/m. Further on the design wave load is almost...... as in the Atlantic and the distance to shore relatively long compared to sites with good wave climate like Ireland, Portugal, Spain and the west coast of UK. The increasing activities within offshore wind in the North Sea and the attempt to build a super grid connecting the wind sites with the major consumers around...

Leatherback sea turtle age and growth

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This study involves analysis of skeletal growth marks in scleral ossicle bones of 33 leatherback sea turtles stranded dead along the Atlantic and Gulf of Mexico US...

Associations between piscine reovirus infection and life history traits in wild-caught Atlantic salmon Salmo salar L. in Norway.

Science.gov (United States)

Garseth, Ase Helen; Biering, Eirik; Aunsmo, Arnfinn

2013-10-01

Piscine Reovirus (PRV), the putative causative agent of heart and skeletal muscle inflammation (HSMI), is widely distributed in both farmed and wild Atlantic salmon (Salmo salar L.) in Norway. While HSMI is a common and commercially important disease in farmed Atlantic salmon, the presence of PRV has so far not been associated with HSMI related lesions in wild salmon. Factors associated with PRV-infection were investigated in returning Atlantic salmon captured in Norwegian rivers. A multilevel mixed-effect logistic regression model confirmed clustering within rivers and demonstrated that PRV-infection is associated with life-history, sex, catch-year and body length as a proxy for sea-age. Escaped farmed salmon (odds ratio/OR: 7.32, p<0.001) and hatchery-reared salmon (OR: 1.69 p=0.073) have higher odds of being PRV-infected than wild Atlantic salmon. Male salmon have double odds of being PRV infected compared to female salmon (OR: 2.11, p<0.001). Odds of being PRV-infected increased with body-length measured as decimetres (OR: 1.20, p=0.004). Since body length and sea-age are correlated (r=0.85 p<0.001), body length serves as a proxy for sea-age, meaning that spending more years in sea increases the odds of being PRV-infected. Copyright © 2013 The Author. Published by Elsevier B.V. All rights reserved.

Improved measurements of mean sea surface velocity in the Nordic Seas from synthetic aperture radar

Science.gov (United States)

Wergeland Hansen, Morten; Johnsen, Harald; Engen, Geir; Øie Nilsen, Jan Even

2017-04-01

The warm and saline surface Atlantic Water (AW) flowing into the Nordic Seas across the Greenland-Scotland ridge transports heat into the Arctic, maintaining the ice-free oceans and regulating sea-ice extent. The AW influences the region's relatively mild climate and is the northern branch of the global thermohaline overturning circulation. Heat loss in the Norwegian Sea is key for both heat transport and deep water formation. In general, the ocean currents in the Nordic Seas and the North Atlantic Ocean is a complex system of topographically steered barotropic and baroclinic currents of which the wind stress and its variability is a driver of major importance. The synthetic aperture radar (SAR) Doppler centroid shift has been demonstrated to contain geophysical information about sea surface wind, waves and current at an accuracy of 5 Hz and pixel spacing of 3.5 - 9 × 8 km2. This corresponds to a horizontal surface velocity of about 20 cm/s at 35° incidence angle. The ESA Prodex ISAR project aims to implement new and improved SAR Doppler shift processing routines to enable reprocessing of the wide swath acquisitions available from the Envisat ASAR archive (2002-2012) at higher resolution and better accuracy than previously obtained, allowing combined use with Sentinel-1 and Radarsat-2 retrievals to build timeseries of the sea surface velocity in the Nordic Seas. Estimation of the geophysical Doppler shift from new SAR Doppler centroid shift retrievals will be demonstrated, addressing key issues relating to geometric (satellite orbit and attitude) and electronic (antenna mis-pointing) contributions and corrections. Geophysical Doppler shift retrievals from one month of data in January 2010 and the inverted surface velocity in the Nordic Seas are then addressed and compared to other direct and indirect estimates of the upper ocean current, in particular those obtained in the ESA GlobCurrent project.

The tropical Atlantic surface wind divergence belt and its effect on clouds

OpenAIRE

Y. Tubul; I. Koren; O. Altaratz

2015-01-01

A well-defined surface wind divergence (SWD) belt with distinct cloud properties forms over the equatorial Atlantic during the boreal summer months. This belt separates the deep convective clouds of the Intertropical Convergence Zone (ITCZ) from the shallow marine stratocumulus cloud decks forming over the cold-water subtropical region of the southern branch of the Hadley cell in the Atlantic. Using the QuikSCAT-SeaWinds and Aqua-MODIS instruments, we examined the large-scal...

Sensitivity of open-water ice growth and ice concentration evolution in a coupled atmosphere-ocean-sea ice model

Science.gov (United States)

Shi, Xiaoxu; Lohmann, Gerrit

2017-09-01

A coupled atmosphere-ocean-sea ice model is applied to investigate to what degree the area-thickness distribution of new ice formed in open water affects the ice and ocean properties. Two sensitivity experiments are performed which modify the horizontal-to-vertical aspect ratio of open-water ice growth. The resulting changes in the Arctic sea-ice concentration strongly affect the surface albedo, the ocean heat release to the atmosphere, and the sea-ice production. The changes are further amplified through a positive feedback mechanism among the Arctic sea ice, the Atlantic Meridional Overturning Circulation (AMOC), and the surface air temperature in the Arctic, as the Fram Strait sea ice import influences the freshwater budget in the North Atlantic Ocean. Anomalies in sea-ice transport lead to changes in sea surface properties of the North Atlantic and the strength of AMOC. For the Southern Ocean, the most pronounced change is a warming along the Antarctic Circumpolar Current (ACC), owing to the interhemispheric bipolar seasaw linked to AMOC weakening. Another insight of this study lies on the improvement of our climate model. The ocean component FESOM is a newly developed ocean-sea ice model with an unstructured mesh and multi-resolution. We find that the subpolar sea-ice boundary in the Northern Hemisphere can be improved by tuning the process of open-water ice growth, which strongly influences the sea ice concentration in the marginal ice zone, the North Atlantic circulation, salinity and Arctic sea ice volume. Since the distribution of new ice on open water relies on many uncertain parameters and the knowledge of the detailed processes is currently too crude, it is a challenge to implement the processes realistically into models. Based on our sensitivity experiments, we conclude a pronounced uncertainty related to open-water sea ice growth which could significantly affect the climate system sensitivity.

Commercial trials using emamectin benzoate to control sea lice Lepeophtheirus salmonis infestations in Atlantic salmon Salmo salar.

Science.gov (United States)

Stone, J; Sutherland, I H; Sommerville, C; Richards, R H; Varma, K J

2000-06-19

Two trials were conducted at commercial salmon farms to evaluate the efficacy of emamectin benzoate (Slice, 0.2% aquaculture pre-mix, Schering-Plough Animal Health) as a treatment for sea lice Lepeophtheirus salmonis (Krøyer) and Caligus elongatus Nordmann infestations in Atlantic salmon Salmo salar L. Trials were carried out in 15 m2 commercial sea pens, at temperatures of 5.5 to 7.5 degrees C and 10.8 to 13.8 degrees C. Each pen was stocked with 14,000 to 17,500 fish with mean weights of 0.44 to 0.74 and 1.33 to 1.83 kg. Fish were naturally infested with sea lice at the start of each trial. At Day -1, samples of 10 or 15 fish were taken from each pen to determine pre-treatment numbers of lice. Emamectin benzoate was administered in feed, to 4 replicate pens, at a dose of 50 micrograms kg-1 biomass d-1 for 7 consecutive days (Days 0 to 6). Sea lice were counted again, between Days 7 and 77, and comparisons made with untreated control fish. Despite adverse weather conditions, wide variations in fish weights and exposure to new infestations, treatment was effective against chalimus and motile stages of L. salmonis. In the autumn trial, efficacy at Day 27 was 89%, and lice numbers remained lower on treated fish than on control fish 64 d from the start of treatment. In the winter trial, reductions in lice numbers at low temperatures were slower but good efficacy was achieved by Day 35. Although control fish had to be treated with hydrogen peroxide at Day 21, fish treated only with emamectin benzoate on Days 0 to 6 still had 89% fewer lice than control fish at Day 35. There were very few C. elongatus present, but at the end of both trials numbers were lower on treated fish. No adverse effects were associated with treatment of fish with emamectin benzoate.

Modeling Biogeochemical-Physical Interactions and Carbon Flux in the Sargasso Sea (Bermuda Atlantic Time-series Study site)

Science.gov (United States)

Signorini, Sergio R.; McClain, Charles R.; Christian, James R.

2001-01-01

An ecosystem-carbon cycle model is used to analyze the biogeochemical-physical interactions and carbon fluxes in the Bermuda Atlantic Time-series Study (BATS) site for the period of 1992-1998. The model results compare well with observations (most variables are within 8% of observed values). The sea-air flux ranges from -0.32 to -0.50 mol C/sq m/yr, depending upon the gas transfer algorithm used. This estimate is within the range (-0.22 to -0.83 mol C/sq m/yr) of previously reported values which indicates that the BATS region is a weak sink of atmospheric CO2. The overall carbon balance consists of atmospheric CO2 uptake of 0.3 Mol C/sq m/yr, upward dissolved inorganic carbon (DIC) bottom flux of 1.1 Mol C/sq m/yr, and carbon export of 1.4 mol C/sq m/yr via sedimentation. Upper ocean DIC levels increased between 1992 and 1996 at a rate of approximately 1.2 (micro)mol/kg/yr, consistent with observations. However, this trend was reversed during 1997-1998 to -2.7 (micro)mol/kg/yr in response to hydrographic changes imposed by the El Nino-La Nina transition, which were manifested in the Sargasso Sea by the warmest SST and lowest surface salinity of the period (1992-1998).

The influence of sea surface temperature anomalies on low-frequency variability of the North Atlantic Oscillation

Energy Technology Data Exchange (ETDEWEB)

Manganello, Julia V. [Center for Ocean-Land-Atmosphere Studies, Calverton, MD (United States)

2008-05-15

The influence of sea surface temperature anomalies (SSTA) on multi-year persistence of the North Atlantic Oscillation (NAO) during the second half of the twentieth century is investigated using the Center for Ocean-Land-Atmosphere Studies (COLA) Atmospheric GCM (AGCM) with an emphasis on isolating the geographic location of the SSTA that produce this influence. The present study focuses on calculating the atmospheric response to the SSTA averaged over 1988-1995 (1961-1968) corresponding to the observed period of strong persistence of the positive (negative) phase of the decadal NAO. The model response to the global 1988-1995 average SSTA shows a statistically significant large-scale pattern characteristic of the positive phase of the NAO. Forcing with the global 1961-1968 average SSTA generates a NAO of the opposite polarity compared to observations. However, all large-scale features both in the model and observations during this period are weaker in magnitude and less significant compared to 1988-1995. Additional idealized experiments show that over the northern center of the NAO the non-linear component of the forced response appears to be quite important and acts to enhance the positive NAO signal. On the other hand, over the southern center where the model response is the strongest, it is also essentially linear. The 1988-1995 average SSTA restricted to the western tropical Pacific region produce a positive NAO remarkably similar in structure but stronger in magnitude than the model response to the global and tropical Indo-Pacific 1988-1995 forcing. A 200-hPa geopotential height response in these experiments shows a positive anomaly over the southern center of the NAO embedded in the Rossby wave trains propagating from the western tropical Pacific. Indian Ocean SSTA lead to much weaker positive NAO primarily through the effect on its northern center. SST forcing confined to the North Atlantic north of equator does not produce a response statistically different

Natural and anthropogenic decadal pH decrease in the North Atlantic and Mediterranean Sea waters

Science.gov (United States)

Huertas, E.; Flecha, S.; Murata, A.; Garcia Lafuente, J.; Pérez, F. F.

2017-12-01

Seawater pH is undergoing a decreasing trend due to atmospheric CO2 absorption, a phenomenon known as Ocean Acidification (OA) that has been documented in different ocean regions. Certain marine basins are more vulnerable to OA, such as the Mediterranean Sea (MS), which is attributed to particular water circulation processes and biogeochemical features. Considering previous studies on OA in Mediterranean and Atlantic water masses, the main aim of this work was to identify for the first time the natural and anthropogenic contribution to decadal pH variations. Therefore, an archetypal analysis was applied to pH measurements and other biogeochemical variables collected in the Strait of Gibraltar during 10 years. Our results reveal that the biological component of the pH change in the Western Mediterranean Deep Water (WMDW) (ΔpHWMDW) represents around 56% of the total decadal pH decrease observed, highlighting the relevance of the remineralization occurring in the Alboran basin, where the WMDW resides before leaving the MS. On the other hand, neither natural nor anthropogenic forcing on the pH change in the Levantine Intermediate Water (ΔpHLIW) was detected, as pH variation was negligible. As for the North Atlantic Central Water (NACW), atmospheric CO2 uptake was responsible of 58% of the ΔpHNACW, likely related to permanent contact with the atmosphere. Additionally, estimations of the approximated ages of the NACW, LIW and WMDW in the SG of about 8, 34 and 32 years respectively have been obtained. Our results show that Mediterranean waters undergo changes in their biogeochemical characteristics during transit through the SG and gives insights on the main mechanisms affecting pH variations occurring from their formation sites to the SG.

Increased susceptibility to infectious salmon anemia virus (ISAv) in Lepeophtheirus salmonis – infected Atlantic salmon

Science.gov (United States)

The salmon louse and infectious salmon anemia virus (ISAv) are the two most significant pathogens of concern to the Atlantic salmon (Salmo salar) aquaculture industry. However, the interactions between sea lice and ISAv, as well as the impact of a prior sea lice infection on the susceptibility of th...

Evidence for ephemeral middle Eocene to early Oligocene Greenland glacial ice and pan-Arctic sea ice.

Science.gov (United States)

Tripati, Aradhna; Darby, Dennis

2018-03-12

Earth's modern climate is defined by the presence of ice at both poles, but that ice is now disappearing. Therefore understanding the origin and causes of polar ice stability is more critical than ever. Here we provide novel geochemical data that constrain past dynamics of glacial ice on Greenland and Arctic sea ice. Based on accurate source determinations of individual ice-rafted Fe-oxide grains, we find evidence for episodic glaciation of distinct source regions on Greenland as far-ranging as ~68°N and ~80°N synchronous with ice-rafting from circum-Arctic sources, beginning in the middle Eocene. Glacial intervals broadly coincide with reduced CO 2 , with a potential threshold for glacial ice stability near ~500 p.p.m.v. The middle Eocene represents the Cenozoic onset of a dynamic cryosphere, with ice in both hemispheres during transient glacials and substantial regional climate heterogeneity. A more stable cryosphere developed at the Eocene-Oligocene transition, and is now threatened by anthropogenic emissions.

Assessing the role of North Atlantic freshwater forcing in millennial scale climate variability: a tropical Atlantic perspective

Energy Technology Data Exchange (ETDEWEB)

Dahl, Kristina A [Massachusetts Institute of Technology/Woods Hole Oceanographic Institution Joint Program, Woods Hole, MA (United States); Broccoli, Anthony J [Rutgers University, Department of Environmental Sciences, New Brunswick, NJ (United States); Stouffer, Ronald J [Geophysical Fluid Dynamics Laboratory, Princeton, NJ (United States)

2005-03-01

This study analyzes a three-member ensemble of experiments, in which 0.1 Sv of freshwater was applied to the North Atlantic for 100 years in order to address the potential for large freshwater inputs in the North Atlantic to drive abrupt climate change. The model used is the GFDL R30 coupled ocean-atmosphere general circulation model. We focus in particular on the effects of this forcing on the tropical Atlantic region, which has been studied extensively by paleoclimatologists. In response to the freshwater forcing, North Atlantic meridional overturning circulation is reduced to roughly 40% by the end of the 100 year freshwater pulse. Consequently, the North Atlantic region cools by up to 8 C. The extreme cooling of the North Atlantic increases the pole-to-equator temperature gradient and requires more heat be provided to the high latitude Atlantic from the tropical Atlantic. To accommodate the increased heat requirement, the ITCZ shifts southward to allow for greater heat transport across the equator. Accompanying this southward ITCZ shift, the Northeast trade winds strengthen and precipitation patterns throughout the tropical Atlantic are altered. Specifically, precipitation in Northeast Brazil increases, and precipitation in Africa decreases slightly. In addition, we find that surface air temperatures warm over the tropical Atlantic and over Africa, but cool over northern South America. Sea-surface temperatures in the tropical Atlantic warm slightly with larger warm anomalies developing in the thermocline. These responses are robust for each member of the ensemble, and have now been identified by a number of freshwater forcing studies using coupled OAGCMs. The model responses to freshwater forcing are generally smaller in magnitude, but have the same direction, as paleoclimate data from the Younger Dryas suggest. In certain cases, however, the model responses and the paleoclimate data directly contradict one another. Discrepancies between the model simulations

Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the METEOR in the Labrador Sea and North Atlantic Ocean from 2003-08-31 to 2003-10-05 (NODC Accession 0115587)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115587 includes chemical, discrete sample, physical and profile data collected from METEOR in the Labrador Sea and North Atlantic Ocean from...

Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the METEOR in the Caribbean Sea and North Atlantic Ocean from 2005-08-13 to 2005-09-19 (NODC Accession 0116566)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0116566 includes chemical, discrete sample, physical and profile data collected from METEOR in the Caribbean Sea and North Atlantic Ocean from...

Remarkable link between projected uncertainties of Arctic sea-ice decline and winter Eurasian climate

Science.gov (United States)

Cheung, Hoffman H. N.; Keenlyside, Noel; Omrani, Nour-Eddine; Zhou, Wen

2018-01-01

We identify that the projected uncertainty of the pan-Arctic sea-ice concentration (SIC) is strongly coupled with the Eurasian circulation in the boreal winter (December-March; DJFM), based on a singular value decomposition (SVD) analysis of the forced response of 11 CMIP5 models. In the models showing a stronger sea-ice decline, the Polar cell becomes weaker and there is an anomalous increase in the sea level pressure (SLP) along 60°N, including the Urals-Siberia region and the Iceland low region. There is an accompanying weakening of both the midlatitude westerly winds and the Ferrell cell, where the SVD signals are also related to anomalous sea surface temperature warming in the midlatitude North Atlantic. In the Mediterranean region, the anomalous circulation response shows a decreasing SLP and increasing precipitation. The anomalous SLP responses over the Euro-Atlantic region project on to the negative North Atlantic Oscillation-like pattern. Altogether, pan-Arctic SIC decline could strongly impact the winter Eurasian climate, but we should be cautious about the causality of their linkage.

Natural Surfactant Enrichments in the Atlantic Ocean Between 50°N and 50°S: Data from the Atlantic Meridional Transect, Oct-Nov 2014

Science.gov (United States)

Sabbaghzadeh, B.; Upstill-Goddard, R. C.; Nightingale, P. D.; Beale, R.

2016-02-01

Surfactants that decrease air-sea gas exchange by suppressing the gas transfer velocity (kw) show variable enrichments in the sea surface microlayer (SML) relative to the underlying water. This reflects variability in the rates of surfactant production and consumption. Total surfactant activity (SA: equivalent to Triton-X-100, mgL -1) was determined daily between the UK and the Falkland Islands, during cruise 24 of the Atlantic Meridional Transect programme (AMT 24). Samples were simultaneously obtained from the SML (Garrett screen), from the ship's underway system (inlet at 7m) and in hydrocasts to 500m. SA analysis was by hanging mercury drop electrode polarography (Metrohm 797 VA Computrace). SA enrichment factors (EF: SML SA / underlying water SA) >1 were observed at most locations, showing the SML to be consistently SA-enriched along the entire cruise transect. The persistence of these enrichments up to wind speeds 12m s-¹ support previous conclusions regarding the stability of the SML under high winds. More specifically, SA in the SML was up to four-fold higher in the Atlantic Northern Hemisphere than in the Atlantic Southern Hemisphere. Even so, EF values were not significantly different between the two hemispheres (p >0.05). These various findings have potentially important implications for kw variability across ocean basin scales.

Impact of the Atlantic Warm Pool on precipitation and temperature in Florida during North Atlantic cold spells

Energy Technology Data Exchange (ETDEWEB)

Donders, Timme H. [Utrecht University, Laboratory of Palaeobotany and Palynology, Institute of Environmental Biology, Utrecht (Netherlands); TNO Geological Survey of the Netherlands, Utrecht (Netherlands); Boer, Hugo Jan de; Dekker, Stefan C. [Utrecht University, Department of Environmental Sciences, Faculty of Geosciences, P.O. Box 80115, Utrecht (Netherlands); Finsinger, Walter; Wagner-Cremer, Friederike [Utrecht University, Laboratory of Palaeobotany and Palynology, Institute of Environmental Biology, Utrecht (Netherlands); Grimm, Eric C. [Research and Collections Center, Illinois State Museum, Springfield, IL (United States); Reichart, Gert Jan [Utrecht University, Geochemistry, Department of Earth Sciences, Faculty of Geosciences, P.O. Box 80021, Utrecht (Netherlands)

2011-01-15

Recurrent phases of increased pine at Lake Tulane, Florida have previously been related to strong stadials terminated by so-called Heinrich events. The climatic significance of these pine phases has been interpreted in different ways. Using a pollen-climate inference model, we quantified the climate changes and consistently found that mean summer precipitation (P{sub JJA}) increased (0.5-0.9 mm/day) and mean November temperature increased (2.0-3.0 C) during pine phases coeval with Heinrich events and the Younger Dryas. Marine sea surface temperature records indicate that potential sources for these moisture and heat anomalies are in the Gulf of Mexico and the western tropical Atlantic. We explain this low latitude warming by an increased Loop Current facilitated by persistence of the Atlantic Warm Pool during summer. This hypothesis is supported by a climate model sensitivity analysis. A positive heat anomaly in the Gulf of Mexico and equatorial Atlantic best approximates the pollen-inferred climate reconstructions from Lake Tulane during the (stadials around) Heinrich events and the Younger Dryas. (orig.)

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

Science.gov (United States)

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

2018-02-01

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

Foraminifera Population from South Africa Coast Line (Indian and Atlantic Oceans

Directory of Open Access Journals (Sweden)

Engin Meriç

2014-11-01

Full Text Available Cape Town is the second-largest city of the Republic of South Africa. Research is conducted in 3 different stations: Maori Bay, which lies in the southwest of Cape Town, and Pyramid Rock and Partridge Points which lies in the False Bay, southeast part of Cape Town. Samples are taken from young sediments at 10.00 and 20.00 m depths, and collected by scuba-diving method. The aim of the study is to investigate the living benthic foraminifera assemblages in the Atlantic Ocean, and to compare these assemblages with the southeastern part of the Atlantic Ocean, the Arabian Sea, Indian Ocean and Western Pacific assemblages. Moreover, the aim of the study is to determine whether there are any benthic foraminifera forms reaching to the Mediterranean from Pacific Ocean, Indian Ocean or Red Sea via Suez Channel.

Thermal niche of Atlantic cod Gadus morhua: limits, tolerance and optima

DEFF Research Database (Denmark)

Righton, David A.; Andersen, Ken Haste; Neat, Francis

2010-01-01

Recent studies in the marine environment have suggested that the limited phenotypic plasticity of cold-adapted species such as Atlantic cod Gadus morhua L. will cause distributions to shift toward the poles in response to rising sea temperatures. Some cod stocks are predicted to collapse, but thi......Recent studies in the marine environment have suggested that the limited phenotypic plasticity of cold-adapted species such as Atlantic cod Gadus morhua L. will cause distributions to shift toward the poles in response to rising sea temperatures. Some cod stocks are predicted to collapse...... niche of approximately 12°C, but latitudinal differences in water temperature meant that cod in the warmer, southern regions experienced 3 times the degree days (DD; ~4000 DD yr–1) than individuals from northern regions (~1200 DD yr–1). Growth rates increased with temperature, reaching a maximum...

BIOMETORE Project - Studying the Biodiversity in the Northeastern Atlantic Seamounts

Science.gov (United States)

Dos Santos, A.; Biscoito, M.; Campos, A.; Tuaty Guerra, M.; Meneses, G.; Santos, A. M. P. A.

2016-02-01

Understanding the deep-sea ecosystem functioning is a key issue in the study of ocean sciences. Bringing together researchers from several scientific domains, the BIOMETORE project aims to the increase knowledge on deep-sea ecosystems and biodiversity at the Atlantic seamounts of the Madeira-Tore and Great Meteor geological complexes. The project outputs will provide important information for the understanding and sustainable management of the target seamount ecosystems, thus contributing to fulfill knowledge gaps on their biodiversity, from bacteria to mammals, and food webs, as well as to promote future sustainable fisheries and sea-floor integrity. The plan includes the realization of eight multidisciplinary surveys, four done during the summer of 2015 and another four planned for the same season of 2016, in target seamounts: the Gorringe bank, the Josephine, and others in the Madeira-Tore, and selected ones in the Greta Meteor (northeastern Atlantic Ocean). The surveys cover a number of scientific areas in the domains of oceanography, ecology, integrative taxonomy, geology, fisheries and spatial mapping. We present and discuss BIOMETORE developments, the preliminary results from the four 2015 summer surveys, and the planning of the next four surveys.

A century of research on the larval distributions of the Atlantic eels: a re-examination of the data

DEFF Research Database (Denmark)

Miller, Michael J.; Bonhommeau, Sylvain; Munk, Peter

2015-01-01

The spawning areas of the Atlantic freshwater eels were discovered about a century ago by the Danish scientist Johannes Schmidt who after years of searching found newly hatched larvae of the European eel, Anguilla anguilla, and the American eel, Anguilla rostrata, in the southern Sargasso Sea...... comprehensive database that includes 22612 A. anguilla and 9634 A. rostrata leptocephali, which provides a detailed view of the spatial and temporal distributions and size of the larvae across the Atlantic basin and in the Mediterranean Sea. The differences in distributions, maximum sizes, and growth rates...

Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the L'ATALANTE in the Caribbean Sea and North Atlantic Ocean from 2003-04-12 to 2003-04-25 (NODC Accession 0117494)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0117494 includes chemical, discrete sample, physical and profile data collected from L'ATALANTE in the Caribbean Sea and North Atlantic Ocean from...

Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the ARANDA in the North Atlantic Ocean and North Greenland Sea from 1997-08-05 to 1997-09-25 (NODC Accession 0115602)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115602 includes chemical, discrete sample, physical and profile data collected from ARANDA in the North Atlantic Ocean and North Greenland Sea from...

Centennial-scale climate change from decadally-paced explosive volcanism: a coupled sea ice-ocean mechanism

Energy Technology Data Exchange (ETDEWEB)

Zhong, Y. [University of Colorado, INSTAAR, Boulder, CO (United States); Miller, G.H. [University of Colorado, INSTAAR, Boulder, CO (United States); University of Colorado, Department of Geological Sciences, Boulder, CO (United States); Otto-Bliesner, B.L.; Holland, M.M.; Bailey, D.A. [NCAR, Boulder, CO (United States); Schneider, D.P. [NCAR, Boulder, CO (United States); University of Colorado, CIRES, Boulder, CO (United States); Geirsdottir, A. [University of Iceland, Department of Earth Sciences and Institute of Earth Sciences, Reykjavik (Iceland)

2011-12-15

Northern Hemisphere summer cooling through the Holocene is largely driven by the steady decrease in summer insolation tied to the precession of the equinoxes. However, centennial-scale climate departures, such as the Little Ice Age, must be caused by other forcings, most likely explosive volcanism and changes in solar irradiance. Stratospheric volcanic aerosols have the stronger forcing, but their short residence time likely precludes a lasting climate impact from a single eruption. Decadally paced explosive volcanism may produce a greater climate impact because the long response time of ocean surface waters allows for a cumulative decrease in sea-surface temperatures that exceeds that of any single eruption. Here we use a global climate model to evaluate the potential long-term climate impacts from four decadally paced large tropical eruptions. Direct forcing results in a rapid expansion of Arctic Ocean sea ice that persists throughout the eruption period. The expanded sea ice increases the flux of sea ice exported to the northern North Atlantic long enough that it reduces the convective warming of surface waters in the subpolar North Atlantic. In two of our four simulations the cooler surface waters being advected into the Arctic Ocean reduced the rate of basal sea-ice melt in the Atlantic sector of the Arctic Ocean, allowing sea ice to remain in an expanded state for > 100 model years after volcanic aerosols were removed from the stratosphere. In these simulations the coupled sea ice-ocean mechanism maintains the strong positive feedbacks of an expanded Arctic Ocean sea ice cover, allowing the initial cooling related to the direct effect of volcanic aerosols to be perpetuated, potentially resulting in a centennial-scale or longer change of state in Arctic climate. The fact that the sea ice-ocean mechanism was not established in two of our four simulations suggests that a long-term sea ice response to volcanic forcing is sensitive to the stability of the seawater

Lionfish (Pterois spp.) invade the upper-bathyal zone in the western Atlantic.

Science.gov (United States)

Gress, Erika; Andradi-Brown, Dominic A; Woodall, Lucy; Schofield, Pamela J; Stanley, Karl; Rogers, Alex D

2017-01-01

Non-native lionfish have been recorded throughout the western Atlantic on both shallow and mesophotic reefs, where they have been linked to declines in reef health. In this study we report the first lionfish observations from the deep sea (>200 m) in Bermuda and Roatan, Honduras, with lionfish observed to a maximum depth of 304 m off the Bermuda platform, and 250 m off West End, Roatan. Placed in the context of other deeper lionfish observations and records, our results imply that lionfish may be present in the 200-300 m depth range of the upper-bathyal zone across many locations in the western Atlantic, but currently are under-sampled compared to shallow habitats. We highlight the need for considering deep-sea lionfish populations in future invasive lionfish management.

Lionfish (Pterois spp. invade the upper-bathyal zone in the western Atlantic

Directory of Open Access Journals (Sweden)

Erika Gress

2017-08-01

Full Text Available Non-native lionfish have been recorded throughout the western Atlantic on both shallow and mesophotic reefs, where they have been linked to declines in reef health. In this study we report the first lionfish observations from the deep sea (>200 m in Bermuda and Roatan, Honduras, with lionfish observed to a maximum depth of 304 m off the Bermuda platform, and 250 m off West End, Roatan. Placed in the context of other deeper lionfish observations and records, our results imply that lionfish may be present in the 200–300 m depth range of the upper-bathyal zone across many locations in the western Atlantic, but currently are under-sampled compared to shallow habitats. We highlight the need for considering deep-sea lionfish populations in future invasive lionfish management.

QUANTIFYING REGIONAL SEA LEVEL RISE CONTRIBUTIONS FROM THE GREENLAND ICE SHEET

Directory of Open Access Journals (Sweden)

Diandong Ren

2013-01-01

Full Text Available This study projects the sea level contribution from the Greenland ice sheet (GrIS through to 2100, using a recently developed ice dynamics model forced by atmospheric parameters derived from three different climate models (CGCMs. The geographical pattern of the near-surface ice warming imposes a divergent flow field favoring mass loss through enhanced ice flow. The calculated average mass loss rate during the latter half of the 21st century is ~0.64±0.06 mm/year eustatic sea level rise, which is significantly larger than the IPCC AR4 estimate from surface mass balance. The difference is due largely to the positive feedbacks from reduced ice viscosity and the basal sliding mechanism present in the ice dynamics model. This inter-model, inter-scenario spread adds approximately a 20% uncertainty to the IPCC ice model estimates. The sea level rise is geographically non-uniform and reaches 1.69±0.24 mm/year by 2100 for the northeast coastal region of the United States, amplified by the expected weakening of the Atlantic meridional overturning circulation (AMOC. In contrast to previous estimates, which neglected the GrIS fresh water input, both sides of the North Atlantic Gyre are projected to experience sea level rises. The impacts on a selection of major cities on both sides of the Atlantic and in the Pacific and southern oceans also are assessed. The other ocean basins are found to be less affected than the Atlantic Ocean.

Towards a robust and consistent middle Eocene astronomical timescale

Science.gov (United States)

Boulila, Slah; Vahlenkamp, Maximilian; De Vleeschouwer, David; Laskar, Jacques; Yamamoto, Yuhji; Pälike, Heiko; Kirtland Turner, Sandra; Sexton, Philip F.; Westerhold, Thomas; Röhl, Ursula

2018-03-01

Until now, the middle Eocene has remained a poorly constrained interval of efforts to produce an astrochronological timescale for the entire Cenozoic. This has given rise to a so-called "Eocene astronomical timescale gap" (Vandenberghe et al., 2012). A high-resolution astrochronological calibration for this interval has proven to be difficult to realize, mainly because carbonate-rich deep-marine sequences of this age are scarce. In this paper, we present records from middle Eocene carbonate-rich sequences from the North Atlantic Southeast Newfoundland Ridge (IODP Exp. 342, Sites U1408 and U1410), of which the cyclical sedimentary patterns allow for an orbital calibration of the geologic timescale between ∼38 and ∼48 Ma. These carbonate-rich cyclic sediments at Sites U1408 and U1410 were deposited as drift deposits and exhibit prominent lithological alternations (couplets) between greenish nannofossil-rich clay and white nannofossil ooze. The principal lithological couplet is driven by the obliquity of Earth's axial tilt, and the intensity of their expression is modulated by a cyclicity of about 173 kyr. This cyclicity corresponds to the interference of secular frequencies s3 and s6 (related to the precession of nodes of the Earth and Saturn, respectively). This 173-kyr obliquity amplitude modulation cycle is exceptionally well recorded in the XRF (X-ray fluorescence)-derived Ca/Fe ratio. In this work, we first demonstrate the stability of the (s3-s6) cycles using the latest astronomical solutions. Results show that this orbital component is stable back to at least 50 Ma, and can thus serve as a powerful geochronometer in the mid-Eocene portion of the Cenozoic timescale. We then exploit this potential by calibrating the geochronology of the recovered middle Eocene timescale between magnetic polarity Chrons C18n.1n and C21n. Comparison with previous timescales shows similarities, but also notable differences in durations of certain magnetic polarity chrons. We

About the seasonal variability of the Alboran Sea circulation

Science.gov (United States)

Vargas-Yáñez, M.; Plaza, F.; García-Lafuente, J.; Sarhan, T.; Vargas, J. M.; Vélez-Belchi, P.

2002-07-01

Data from a mooring line deployed midway between the Alboran Island and Cape Tres Forcas are used to study the time variability of the Alboran Sea from May 1997 to May 1998. The upper layer salinity and zonal velocity present annual and semiannual cycles characterised by a minimum in spring and autumn and a maximum in summer and winter. Temperature has the opposite behaviour to that of salinity indicating changes in the presence of the Atlantic water within the Alboran Passage. A large set of SST images is used to study these cycles. The decrease of salinity and velocity in our mooring location in spring and autumn seems to be related to the eastward drifting of the Western Alboran Gyre (WAG). The increase of salinity and velocity is caused by the Atlantic current flowing south of the Alboran Island and its associated thermohaline front. Conductivity-temperature-depth (CTD) data from two cruises along the 3°W are coherent with current meters and SST interpretations. During the period analysed, summer months are characterised by the stability of the two-gyre system, while in winter, the circulation is characterised by a coastal jet flowing close to the African shore. We use sea level differences across the Strait of Gibraltar for studying the variability of the Atlantic inflow. We discuss the changes in the Alboran Sea circulation and its relation with the variability of the inertial radius of the Atlantic inflow. Though our results are speculative, we find a possible relation between the disappearance of the two-gyre system and a reversal of the circulation in Gibraltar. Longer time series are needed to conclude, but comparison with previous works makes us think that the seasonal cycle described from May 1997 to May 1998 could be the most likely one for the Alboran Sea upper layer.

Accelerated sea level rise and Florida Current transport

Directory of Open Access Journals (Sweden)

J. Park

2015-07-01

Full Text Available The Florida Current is the headwater of the Gulf Stream and is a component of the North Atlantic western boundary current from which a geostrophic balance between sea surface height and mass transport directly influence coastal sea levels along the Florida Straits. A linear regression of daily Florida Current transport estimates does not find a significant change in transport over the last decade; however, a nonlinear trend extracted from empirical mode decomposition (EMD suggests a 3 Sv decline in mean transport. This decline is consistent with observed tide gauge records in Florida Bay and the straits exhibiting an acceleration of mean sea level (MSL rise over the decade. It is not known whether this recent change represents natural variability or the onset of the anticipated secular decline in Atlantic meridional overturning circulation (AMOC; nonetheless, such changes have direct impacts on the sensitive ecological systems of the Everglades as well as the climate of western Europe and eastern North America.

Daytime sea fog retrieval based on GOCI data: a case study over the Yellow Sea.

Science.gov (United States)

Yuan, Yibo; Qiu, Zhongfeng; Sun, Deyong; Wang, Shengqiang; Yue, Xiaoyuan

2016-01-25

In this paper, a new daytime sea fog detection algorithm has been developed by using Geostationary Ocean Color Imager (GOCI) data. Based on spectral analysis, differences in spectral characteristics were found over different underlying surfaces, which include land, sea, middle/high level clouds, stratus clouds and sea fog. Statistical analysis showed that the Rrc (412 nm) (Rayleigh Corrected Reflectance) of sea fog pixels is approximately 0.1-0.6. Similarly, various band combinations could be used to separate different surfaces. Therefore, three indices (SLDI, MCDI and BSI) were set to discern land/sea, middle/high level clouds and fog/stratus clouds, respectively, from which it was generally easy to extract fog pixels. The remote sensing algorithm was verified using coastal sounding data, which demonstrated that the algorithm had the ability to detect sea fog. The algorithm was then used to monitor an 8-hour sea fog event and the results were consistent with observational data from buoys data deployed near the Sheyang coast (121°E, 34°N). The goal of this study was to establish a daytime sea fog detection algorithm based on GOCI data, which shows promise for detecting fog separately from stratus.

Sea Turtle Bycatch Mitigation in U.S. Longline Fisheries

Directory of Open Access Journals (Sweden)

Yonat Swimmer

2017-08-01

Full Text Available Capture of sea turtles in longline fisheries has been implicated in population declines of loggerhead (Caretta caretta and leatherback (Dermochelys coriacea turtles. Since 2004, United States (U.S. longline vessels targeting swordfish and tunas in the Pacific and regions in the Atlantic Ocean have operated under extensive fisheries regulations to reduce the capture and mortality of endangered and threatened sea turtles. We analyzed 20+ years of longline observer data from both ocean basins during periods before and after the regulations to assess the effectiveness of the regulations. Using generalized additive mixed models (GAMMs, we investigated relationships between the probability of expected turtle interactions and operational components such as fishing location, hook type, bait type, sea surface temperature, and use of light sticks. GAMMs identified a two to three-fold lower probability of expected capture of loggerhead and leatherback turtle bycatch in the Atlantic and Pacific when circle hooks are used (vs. J hook. Use of fish bait (vs. squid was also found to significantly reduce the capture probability of loggerheads in both ocean basins, and for leatherbacks in the Atlantic only. Capture probabilities are lowest when using a combination of circle hook and fish bait. Influences of light sticks, hook depth, geographic location, and sea surface temperature are discussed specific to species and regions. Results confirmed that in two U.S.-managed longline fisheries, rates of sea turtle bycatch significantly declined after the regulations. In the Atlantic (all regions, rates declined by 40 and 61% for leatherback and loggerhead turtles, respectively, after the regulations. Within the NED area alone, where additional restrictions include a large circle hook (18/0 and limited use of squid bait, rates declined by 64 and 55% for leatherback and loggerhead turtles, respectively. Gains were even more pronounced for the Pacific shallow set fishery

Biogeochemical and Optical Analysis of Coastal DOM for Satellite Retrieval of Terrigenous DOM in the U.S. Middle Atlantic Bight

Science.gov (United States)

Mannino, A.; Dyda, R. Y.; Hernes, P. J.; Hooker, Stan; Hyde, Kim; Novak, Mike

2012-01-01

Estuaries and coastal ocean waters experience a high degree of variability in the composition and concentration of particulate and dissolved organic matter (DOM) as a consequence of riverine/estuarine fluxes of terrigenous DOM, sediments, detritus and nutrients into coastal waters and associated phytoplankton blooms. Our approach integrates biogeochemical measurements (elemental content, molecular analyses), optical properties (absorption) and remote sensing to examine terrestrial DOM contributions into the U.S. Middle Atlantic Bight (MAB). We measured lignin phenol composition, DOC and CDOM absorption within the Chesapeake and Delaware Bay mouths, plumes and adjacent coastal ocean waters to derive empirical relationships between CDOM and biogeochemical measurements for satellite remote sensing application. Lignin ranged from 0.03 to 6.6 ug/L between estuarine and outer shelf waters. Our results demonstrate that satellite-derived CDOM is useful as a tracer of terrigenous DOM in the coastal ocean

Early-to-middle Holocene sea-level fluctuations, coastal progradation and the Neolithic occupations in Yaojiang valley of southern Hangzhou bay, eastern China

Science.gov (United States)

Liu, Y.; Sun, Q.; Fan, D.; Chen, Z.

2017-12-01

The formation of Holocene coast in eastern China provided material base for the development of Neolithic civilizations. The coastal Yaojiang valley of south Hangzhou bay was one of the examples where the well-known Neolithic Hemudu Culture (HC) of Eastern China initiated. Here, we studied the early-to-middle Holocene environment changes in relation to sea-level fluctuations on the basis of a serial of sediment cores based on a set of new Accelerator Mass Spectrometry radiocarbon (AMS 14C) chronology. The result indicated that relative sea-level rose rapidly in the Yaojiang valley at the early Holocene, reaching its maximum at ca. 8000-7800 cal yr BP and then decelerated at ca. 7800-7500 cal yr BP. The alluvial plain in Yaojiang valley began to form at the foothills first and then grew towards the valley center accompanying with the sea-level stabilization after ca. 7500 cal yr BP. This progressive progradation of alluvial plain would attract the early arrivals of foragers to dwell at the foothills to engaging in rice farming after ca.7000 cal yr BP and starting the epic Hemudu Culture. The HC people then move down to the valley center as more land became available thanks to sediment aggregation and progradation. The rise and development of HC were closely associated with the sea-level induced landscape changes in Yaojiang valley at the early-middle Holocene, and the unstable hydraulic condition in the valley after 5000 cal yr BP could be accountable for the cultural termination.

Scottish Sea Lochs: High Resolution Archives of North Atlantic Climate

Science.gov (United States)

Norgaard-Pedersen, N.; Austin, W. E.; Cage, A. G.; Shimmield, T. M.; Gillibrand, P. A.

2002-12-01

The sea lochs (fjords) of NW Scotland bridge the land-ocean interface in a region of Europe which is particularly well situated to monitor changes in westerly air flow. Inter-annual atmospheric circulation changes at this latitude are largely governed by the North Atlantic Oscillation (NAO), in turn influencing both westerlies and precipitation. Comparing two extreme recent NAO years, circulation modelling results from Loch Sunart, NW Scotland, reveal a clear response to freshwater runoff and wind forcing in both magnitude and rate of deep-water renewal events. Scottish fjords, because of the relatively small impact which salinity has on d18Owater (0.18 % per salinity unit), potentially provide NW Europe's most useful study sites in coastal palaeoclimate research, particularly where palaeotemperature is the primary record of interest. New data from a high-resolution record (7 yr sample resolution), spanning the last two millennia, from the deepest part of the main basin of Loch Sunart illustrate significant multi-decadal to centennial scale variability in the sedimentary and stable isotope record of epibenthic foraminifera Cibicides lobatulus. The long-term pattern in benthic d18O appears to reflect bottom water temperature differences of 1-2§C, resolving climatic periods such as the Medieval Warm Period and the Little Ice Age. Since the core site is connected with shelf waters (i.e. no shallow sill) it seems likely that this paleotemperature reflects changing shelf water, not the exchange process as a function of long-term runoff/wind forcing. Grain size data and XRF data point to catchment-wide responses (weathering and erosion) which appear to show the largest variability during the last millennium, driven either by rainfall and temperature and/or land-use. Pb-isotope data, constraining the modern and industrial period, suggest accelerated sedimentation rates over this interval. On-going work attempts to calibrate proxy data with instrumental historical data.

Nordic Seas nutrients data in CARINA

Directory of Open Access Journals (Sweden)

J. Olafsson

2010-09-01

Full Text Available Water column data of carbon and carbon relevant hydrographic and hydrochemical parameters from 188 cruises in the Arctic, Atlantic, and Southern Ocean have been assembled and the collection merged into a new database: CARINA (CARbon IN the Atlantic. The data have been subject to rigorous quality control (QC in order to ensure highest possible quality and consistency. The data for most of the parameters included were examined in order to quantify systematic biases in the reported values, i.e. secondary quality control. Significant biases have been corrected for in the data products, i.e. the three merged files with measured, calculated and interpolated values for each of the three CARINA regions; the Arctic Mediterranean Seas (AMS, the Atlantic (ATL and the Southern Ocean (SO. With the adjustments, the CARINA database is consistent both internally as well as with GLODAP (Key et al., 2004 and is suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates, and for model validation. The Arctic Mediterranean Seas is the collective term for the Arctic Ocean and the Nordic Seas, and the quality control was carried out separately in these two areas. This contribution presents an account of the quality control of the nutrients (nitrate, phosphate, and silicate data from the Nordic Seas in CARINA. Out of the 35 cruises from the Nordic Seas included in CARINA, 33 had nutrients data. The nitrate data from 4 of these appeared to be of so poor quality that they should not be used, for phosphate this number is 7 and for silicate it is 3. We also recommend that the nitrate data from 4 of the cruises should be adjusted, for phosphate and silicate only data from one cruise should be adjusted. The final data appears consistent to 5% based on evaluation of deep data. For nitrate this corresponds to 0.6 μmol kg⁻¹, and for phosphate and silicate it corresponds to 0.04 and 0.6 μmol kg⁻¹, respectively.

Linear magnetic anomalies and tectonic development of the middle Okinawa Trough

Institute of Scientific and Technical Information of China (English)

无

2001-01-01

-By analyzing the magnetic anomalies, the linear magnetic anomalies in the middle Okinawa Trough are identified. It means that the crust along the spreading axis is broken, and new oceanic crust is formed. Geophysical data have revealed that a model of three extensive episodes occurs in the Okinawa Trough, which can be named as "doming episode" from the Middle to Late Miocene (Phase I), the episode from the Pliocence to Early Pleistocene (Phase Ⅱ ), and the recent "spreading episode" (Phase Ⅲ ). The magnetic anomalies in the middle Okinawa Trough are very similar to those found in the middle Red Sea, indicating that the Okinawa Trough is developing towards the "Red Sea stage". Similar to the Red Sea, there are a "main trough" and a "axial trough" in the Okinawa Trough.

Pronounced zonal heterogeneity in Eocene southern high-latitude sea surface temperatures.

Science.gov (United States)

Douglas, Peter M J; Affek, Hagit P; Ivany, Linda C; Houben, Alexander J P; Sijp, Willem P; Sluijs, Appy; Schouten, Stefan; Pagani, Mark

2014-05-06

Paleoclimate studies suggest that increased global warmth during the Eocene epoch was greatly amplified at high latitudes, a state that climate models cannot fully reproduce. However, proxy estimates of Eocene near-Antarctic sea surface temperatures (SSTs) have produced widely divergent results at similar latitudes, with SSTs above 20 °C in the southwest Pacific contrasting with SSTs between 5 and 15 °C in the South Atlantic. Validation of this zonal temperature difference has been impeded by uncertainties inherent to the individual paleotemperature proxies applied at these sites. Here, we present multiproxy data from Seymour Island, near the Antarctic Peninsula, that provides well-constrained evidence for annual SSTs of 10-17 °C (1σ SD) during the middle and late Eocene. Comparison of the same paleotemperature proxy at Seymour Island and at the East Tasman Plateau indicate the presence of a large and consistent middle-to-late Eocene SST gradient of ∼7 °C between these two sites located at similar paleolatitudes. Intermediate-complexity climate model simulations suggest that enhanced oceanic heat transport in the South Pacific, driven by deep-water formation in the Ross Sea, was largely responsible for the observed SST gradient. These results indicate that very warm SSTs, in excess of 18 °C, did not extend uniformly across the Eocene southern high latitudes, and suggest that thermohaline circulation may partially control the distribution of high-latitude ocean temperatures in greenhouse climates. The pronounced zonal SST heterogeneity evident in the Eocene cautions against inferring past meridional temperature gradients using spatially limited data within given latitudinal bands.

Tropical North Atlantic ocean-atmosphere interactions synchronize forest carbon losses from hurricanes and Amazon fires

Science.gov (United States)

Chen, Yang; Randerson, James T.; Morton, Douglas C.

2015-08-01

We describe a climate mode synchronizing forest carbon losses from North and South America by analyzing time series of tropical North Atlantic sea surface temperatures (SSTs), landfall hurricanes and tropical storms, and Amazon fires during 1995-2013. Years with anomalously high tropical North Atlantic SSTs during March-June were often followed by a more active hurricane season and a larger number of satellite-detected fires in the southern Amazon during June-November. The relationship between North Atlantic tropical cyclones and southern Amazon fires (r = 0.61, p forests.

77 FR 68723 - Fisheries of the Northeastern United States; Summer Flounder, Scup, and Black Sea Bass Fisheries...

Science.gov (United States)

2012-11-16

... flounder, scup, black sea bass, longfin squid, butterfish, and Atlantic bluefish fisheries. If the total... of butterfish; and 715,830 lb of bluefish. For 2014, projects may collectively be awarded up to 587... Atlantic bluefish, and assessment-quality data for weakfish, Atlantic croaker, spot, several skate and ray...

Winter distribution of Calanus finmarchicus in the Northeast Atlantic

DEFF Research Database (Denmark)

Heath, M.R.; Fraser, J.G.; Gislason, A.

2000-01-01

Data from plankton sampling and Optical Plankton Counter deployments during six cruises between December of 1994 and 1999 have been used to derive a composite three-dimensional distribution of the abundance of Calanus finmarchicus during winter (December-January) in the Norwegian Sea and Northeast...... Northeast Atlantic, the concentration of wintering animals is around 30% of that in the Norwegian Sea and the vertical distribution is more diffuse and on average deeper. Modelling studies have shown that the overwinter distribution and transport are key factors determining the spatial persistence of C...

Deepwater Horizon oil spill impacts on sea turtles could span the Atlantic.

Science.gov (United States)

Putman, Nathan F; Abreu-Grobois, F Alberto; Iturbe-Darkistade, Iñaky; Putman, Emily M; Richards, Paul M; Verley, Philippe

2015-12-01

We investigated the extent that the 2010 Deepwater Horizon oil spill potentially affected oceanic-stage sea turtles from populations across the Atlantic. Within an ocean-circulation model, particles were backtracked from the Gulf of Mexico spill site to determine the probability of young turtles arriving in this area from major nesting beaches. The abundance of turtles in the vicinity of the oil spill was derived by forward-tracking particles from focal beaches and integrating population size, oceanic-stage duration and stage-specific survival rates. Simulations indicated that 321 401 (66 199-397 864) green (Chelonia mydas), loggerhead (Caretta caretta) and Kemp's ridley (Lepidochelys kempii) turtles were likely within the spill site. These predictions compared favourably with estimates from in-water observations recently made available to the public (though our initial predictions for Kemp's ridley were substantially lower than in-water estimates, better agreement was obtained with modifications to mimic behaviour of young Kemp's ridley turtles in the northern Gulf). Simulations predicted 75.2% (71.9-76.3%) of turtles came from Mexico, 14.8% (11-18%) from Costa Rica, 5.9% (4.8-7.9%) from countries in northern South America, 3.4% (2.4-3.5%) from the United States and 1.6% (0.6-2.0%) from West African countries. Thus, the spill's impacts may extend far beyond the current focus on the northern Gulf of Mexico. © 2015 The Authors.

The spatial distribution and evolution characteristics of North Atlantic cyclones

Science.gov (United States)

Dacre, H.; Gray, S.

2009-09-01

Mid-latitude cyclones play a large role in determining the day-to-day weather conditions in western Europe through their associated wind and precipitation patterns. Thus, their typical spatial and evolution characteristics are of great interest to meteorologists, insurance and risk management companies. In this study a feature tracking algorithm is applied to a cyclone database produced using the Hewson-method of cyclone identification, based on low-level gradients of wet-bulb potential temperature, to produce a climatology of mid-latitude cyclones. The aim of this work is to compare the cyclone track and density statistics found in this study with previous climatologies and to determine reasons for any differences. This method is found to compare well with other cyclone identification methods; the north Atlantic storm track is reproduced along with the major regions of genesis. Differences are attributed to cyclone lifetime and strength thresholds, dataset resolution and cyclone identification and tracking methods. Previous work on cyclone development has been largely limited to case studies as opposed to analysis of climatological data, and does not distinguish between the different stages of cyclone evolution. The cyclone database used in this study allows cyclone characteristics to be tracked throughout the cyclone lifecycle. This enables the evaluation of the characteristics of cyclone evolution for systems forming in different genesis regions and a calculation of the spatial distribution and evolution of these characteristics in composite cyclones. It was found that most of the cyclones that cross western Europe originate in the east Atlantic where the baroclinicity and sea surface temperature gradients are weak compared to the west Atlantic. East Atlantic cyclones also have higher low-level relative vorticity and lower mean sea level pressure at their genesis point than west Atlantic cyclones. This is consistent with the hypothesis that they are secondary

78 FR 77428 - 2014 Annual Determination for Sea Turtle Observer Requirement

Science.gov (United States)

2013-12-23

... listed as endangered or threatened. All sea turtles found in U.S. waters are listed as either endangered... imbricata) sea turtles are listed as endangered. Loggerhead (Caretta caretta; Northwest Atlantic distinct... and olive ridley turtles away from the nesting beach, NMFS considers these turtles endangered wherever...

Dissolved inorganic carbon, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the HUDSON in the Labrador Sea and North Atlantic Ocean from 1992-05-27 to 1992-06-15 (NODC Accession 0113550)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113550 includes chemical, discrete sample, physical and profile data collected from HUDSON in the Labrador Sea and North Atlantic Ocean from...

MICROSTRUCTURE OF THE MID-INTESTINE OF CERTAIN CARP FISH (CIPRINIDAE IN THE WESTERN PART OF THE MIDDLE CASPIAN SEA

Directory of Open Access Journals (Sweden)

N. I. Rabazanov

2016-01-01

Full Text Available Aim. The aim of the study was an attempt to expand on the findings about the structure of the anterior part of the mid-intestine of three species of carp fish: Rutelus frisii kutum (Kamenski, Abramis brama orientalis and Ciprinus caprio (Linne in connection with the feeding habits in the changed conditions of the western coast of the Middle Caspian sea. Studies of the digestive tract can extend the idea of the specifics of the mid-intestine structure due to the feeding of fish in certain environmental conditions of habitat.Methods. Investigations of the digestive tract were carried out, guided by the "Methodological manual" by I.V. Verigina.Findings and discussion. It is shown that in the anatomical and histological structure of the middle intestine was affected by the feeding habits of these types of fish; feeding upon small and soft invertebrates leads to a relatively simple structure of the intestinal wall: mucous layer covers a small part of the total thickness of the wall; there are no collagen structures that perform the function of the mechanical frame and capsules around blood vessels.Conclusion. Simplification of the digestive system emphasizes adaptive capacity appearing in periodic fluctuation of sea water level. The absence of food of a bigger size in the diet of fish results in a relatively simple anatomical and histological structure of the mid-intestine wall. None of the species under study has a differentiated stomach; instead its role is taken by an expanded portion of the fore intestine, similar is the microstructure of the middle part of the intestines of all three species.

Deglacial climate modulated by the storage and release of Arctic sea ice

Science.gov (United States)

Condron, A.; Coletti, A. J.; Bradley, R. S.

2017-12-01

Periods of abrupt climate cooling during the last deglaciation (20 - 8 kyr ago) are often attributed to glacial outburst floods slowing the Atlantic meridional overturning circulation (AMOC). Here, we present results from a series of climate model simulations showing that the episodic break-up and mobilization of thick, perennial, Arctic sea ice during this time would have released considerable volumes of freshwater directly to the Nordic Seas, where processes regulating large-scale climate occur. Massive sea ice export events to the North Atlantic are generated whenever the transport of sea ice is enhanced, either by changes in atmospheric circulation, rising sea level submerging the Bering land bridge, or glacial outburst floods draining into the Arctic Ocean from the Mackenzie River. We find that the volumes of freshwater released to the Nordic Seas are similar to, or larger than, those estimated to have come from terrestrial outburst floods, including the discharge at the onset of the Younger Dryas. Our results provide the first evidence that the storage and release of Arctic sea ice helped drive deglacial climate change by modulating the strength of the AMOC.

Fourier transform near-infrared spectroscopy application for sea salt quality evaluation.

Science.gov (United States)

Galvis-Sánchez, Andrea C; Lopes, João Almeida; Delgadillo, Ivonne; Rangel, António O S S

2011-10-26

Near-infrared (NIR) spectroscopy in diffuse reflectance mode was explored with the objective of discriminating sea salts according to their quality type (traditional salt vs "flower of salt") and geographical origin (Atlantic vs Mediterranean). Sea salts were also analyzed in terms of Ca(2+), Mg(2+), K(+), alkalinity, and sulfate concentrations to support spectroscopic results. High concentrations of Mg(2+) and K(+) characterized Atlantic samples, while a high Ca(2+) content was observed in traditional sea salts. A partial least-squares discriminant analysis model considering the 8500-7500 cm(-1) region permitted the discrimination of salts by quality types. The regions 4650-4350 and 5900-5500 cm(-1) allowed salts classification according to their geographical origin. It was possible to classify correctly 85.3 and 94.8% of the analyzed samples according to the salt type and to the geographical origin, respectively. These results demonstrated that NIR spectroscopy is a suitable and very efficient tool for sea salt quality evaluation.

Distributions and habitat associations of deep-water corals in Norfolk and Baltimore Canyons, Mid-Atlantic Bight, USA

NARCIS (Netherlands)

Brooke, S.D.; Watts, M.W.; Heil, A.D.; Rhode, M.; Mienis, F.; Duineveld, G.C.A.; Davies, A.J.; Ross, S.W.

2017-01-01

A multi-disciplinary study of two major submarine canyons, Baltimore Canyon and Norfolk Canyon, off the US mid-Atlantic coast focused on the ecology and biology of canyon habitats, particularly those supporting deep-sea corals. Historical data on deep-sea corals from these canyons were sparse with

Radioactivity in the northern seas of europe

International Nuclear Information System (INIS)

Carvalho, Fernando P.; Madruga, Maria Jose; Oliveira, Joao M.; Gouveia, Jorge M.; Silva, Lidia

2004-01-01

The recent accidents with nuclear powered Russian submarines, such as the Kursk and the K-159, that took place in the Arctic Seas, give rise to high concerns of the public and the media about the radioactive contamination of marine ecosystems and radiological safety of the European population. Those accidents were preceded by decades of discharges of radioactive liquid effluents into coastal seas of Europe and the dumping of packed radioactive waste into the North Atlantic. Being Portugal one country with high consumption rate of seafood caught in its own coastal waters as well as in far seas including the Ar tic seas, the investigation of the radioactive contamination of fish was investigated. Analysis of fish from the Sea of Labrador, Sea of Iceland and Barents Sea, has shown that gamma-emitting radionuclides of artificial origin are in general not detected. The only gamma emitting radionuclide present is Cs-137, in concentrations not higher than 0.3 Bq/kg. This radionuclide originates in the deposition of radioactive fallout following nuclear weapon tests performed in the fifties and sixties. Radionuclides in fish from northern regions and in fish from the Portuguese coast generally are present in concentrations lower than those currently reported for fish from the Irish Sea and the Baltic Sea, impacted with the discharges of radioactive waste from Sellafield and the deposition of fallout from Chernobyl, respectively. Nevertheless, the potential for future accidents and the radioactive waste dumped into the North Atlantic may in the future modify this scenario and potentially increase the currently very low radionuclide concentration in fish included in the Portuguese diet. Therefore, the research and radiological surveillance must be maintained in order to monitor the radiological risk and to ensure the quality of food available to consumers. (author)

Polychlorinated biphenyl (PCB) load, lipid reserves and biotransformation activity in migrating Atlantic salmon from River Moerrum, Sweden

International Nuclear Information System (INIS)

Hansson, Maria C.; Persson, Maria E.; Larsson, Per; Schantz, Torbjoern von

2009-01-01

Atlantic salmon accumulate high levels of contaminants such as polychlorinated biphenyls (PCBs) in their lipids during the adult growth phase spent at sea. The lipids are later utilized during migration for swimming and biological adaptations. We hypothesize that migrating salmons' biotransformation processes are affected by the high levels of built-up PCBs compared to salmon that in a pre-migrational stage. For these analyses we sampled adult Atlantic salmon during migration in the Swedish River Moerrum and measured the 21 most common PCB congeners (ΣPCB) and lipid levels in muscle tissue, aryl hydrocarbon receptor (AHR2) and cytochrome P4501A1 (CYP1A1) transcript levels as well as ethoxyresorufin-O-deethylase activity (EROD) in liver. We also determined which AHR2 genotypes the salmon carried. We show that EROD activity is correlated to CYP1A1 level but not to ΣPCB concentration. ΣPCB concentration does not predict levels of neither the AHR2 nor CYP1A1 genes. We find no associations between specific AHR2 transcription levels and AHR2 genotypes or a correlation between AHR2 and CYP1A1 transcription levels, which is in direct contrast to pre-migrational adult salmon from the Baltic Sea. When we compare River Moerrum to salmon we have previously sampled in the Baltic Sea we show that migrating salmon have significantly lower lipid levels in their muscles; higher muscle concentrations of ΣPCB on a lipid basis; and significantly lower CYP1A1 and EROD levels compared to salmon from the Baltic Sea. Also, transcript levels of three out of four AHR2 genes are significantly different. In conclusion, migrating Swedish Atlantic salmon carry higher concentrations of PCBs in their lipids compared to salmon in the Baltic Sea, but have lower activation of biotransformation genes and enzymes. Our results indicate that accumulated pollutants from the Baltic Sea are deactivated inside the migrating salmon's lipid tissues and increase in concentration when migration is initiated

PH, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from Sarmiento de Gamboa in the Labrador Sea and North Atlantic Ocean from 2012-06-22 to 2012-07-20 (NCEI Accession 0156920)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0156920 includes chemical, discrete sample, physical and profile data collected from Sarmiento de Gamboa in the Labrador Sea and North Atlantic Ocean...

An Abyssal Current in the Central Labrador Sea

Science.gov (United States)

Hall, M. M.; Yashayaev, I.; Torres, D. J.

2012-12-01

Lowered acoustic Doppler current profiler (LADCP) data collected along the repeat hydrographic section AR7W in the Labrador Sea has unveiled a new abyssal current, confined to a narrow trench extending from NW to SE over the entire abyssal basin and crossing AR7W in the center of the basin at about 57.8°N, 51.3°W. Maximum water depth in the trough is 75 - 100 m greater depth than the surrounding topography, and the current extends from about 160 m above the bottom to the bottom (3610 m), headed in a south to southeasterly direction. Maximum speeds of 10-20 cm s-1 occur in the deepest part of the current, implying a net transport of as much as 0.2 Sv of Denmark Strait Overflow Water (DSOW). Potential temperature and salinity in the bottom-intensified current tend to be well mixed below 3520 m, suggesting that the mixed bottom boundary layer is about 100 m thick. This V-shaped trench is part of the Northwest Atlantic Mid-Ocean Channel (NAMOC), which has been recognized as a turbidity current pathway by petrologists (Chough and Hesse, 1980; Chough et al., 1986). Another small trough intersects the main branch of the NAMOC where the abyssal current is observed, which may account for the varying direction of the current. This network of abyssal channels may provide a pathway for DSOW, entering the Labrador Sea around the southern tip of Greenland, to reach the central Labrador Sea with little delay. Indeed, Yashayaev and Dickson (2008) have noted the rapidity with which signals of hydrographic change in DSOW spread across the entire abyssal basin, reaching the central Labrador Sea within several months after their first appearance at the eastern boundary. Chough, S. K. and R. Hesse (1980). The Northwest Atlantic Mid-Ocean Channel of the Labrador Sea: III. Head spill vs. body spill deposits from turbidity currents on natural levees. J. of Sedimentary Petrology 50, 227-234. Chough, S. K., R. Hesse, and J. Muller (1987). The Northwest Atlantic Mid-Ocean Channel of the

Moisture transport from the Atlantic to the Pacific basin and its response to North Atlantic cooling and global warming

Energy Technology Data Exchange (ETDEWEB)

Richter, Ingo [University of Hawaii at Manoa, International Pacific Research Center, Honolulu, HI (United States); Xie, Shang-Ping [University of Hawaii at Manoa, Department of Meteorology, Honolulu, HI (United States)

2010-08-15

Atmospheric moisture transport from the Atlantic to the Pacific basin plays an important role in regulating North Atlantic salinity and thus the strength of the thermohaline circulation. Potential changes in the strength of this moisture transport are investigated for two different climate-change scenarios: North Atlantic cooling representative of Heinrich events, and increased greenhouse gas (GHG) forcing. The effect of North Atlantic cooling is studied using a coupled regional model with comparatively high resolution that successfully simulates Central American gap winds and other important aspects of the region. Cooler North Atlantic sea surface temperature (SST) in this model leads to a regional decrease of atmospheric moisture but also to an increase in wind speed across Central America via an anomalous pressure gradient. The latter effect dominates, resulting in a 0.13 Sv (1 Sv = 10{sup 6} m{sup 3} s{sup -1}) increase in overall moisture transport to the Pacific basin. In fresh water forcing simulations with four different general circulation models, the wind speed effect is also present but not strong enough to completely offset the effect of moisture decrease except in one model. The influence of GHG forcing is studied using simulations from the Intergovernmental Panel on Climate Change archive. In these simulations atmospheric moisture increases globally, resulting in an increase of moisture transport by 0.25 Sv from the Atlantic to Pacific. Thus, in both scenarios, moisture transport changes act to stabilize the thermohaline circulation. The notion that the Andes effectively block moisture transport from the Atlantic to the Pacific basin is not supported by the simulations and atmospheric reanalyses examined here. This indicates that such a blocking effect does not exist or else that higher resolution is needed to adequately represent the steep orography of the Andes. (orig.)

Cold-season atmospheric response to the natural variability of the Atlantic meridional overturning circulation

Energy Technology Data Exchange (ETDEWEB)

Gastineau, Guillaume; Frankignoul, Claude [LOCEAN/IPSL, Universite Pierre et Marie Curie, 4 place Jussieu, BP100, Paris Cedex 05 (France)

2012-07-15

The influence of the natural variability of the Atlantic meridional overturning circulation (AMOC) on the atmosphere is studied in multi-centennial simulations of six global climate models, using Maximum Covariance Analysis (MCA). In all models, a significant but weak influence of the AMOC changes is found during the Northern Hemisphere cold-season, when the ocean leads the atmosphere by a few years. Although the oceanic pattern slightly varies, an intensification of the AMOC is followed in all models by a weak sea level pressure response that resembles a negative phase of the North Atlantic Oscillation (NAO). The signal amplitude is typically 0.5 hPa and explains about 10% of the yearly variability of the NAO in all models. The atmospheric response seems to be due primarily due to an increase of the heat loss along the North Atlantic Current and the subpolar gyre, associated with an AMOC-driven warming. Sea-ice changes appear to be less important. The stronger heating is associated to a southward shift of the lower-tropospheric baroclinicity and a decrease of the eddy activity in the North Atlantic storm track, which is consistent with the equivalent barotropic perturbation resembling the negative phase of the NAO. This study thus provides some evidence of an atmospheric signature of the AMOC in the cold-season, which may have some implications for the decadal predictability of climate in the North Atlantic region. (orig.)

Mechanisms of the atmospheric response to North Atlantic multidecadal variability: a model study

Energy Technology Data Exchange (ETDEWEB)

Msadek, Rym [Universite Pierre et Marie Curie-Paris 6, LOCEAN/IPSL, Paris Cedex 05 (France); Princeton University, GFDL/NOAA, AOS Program, Princeton, NJ (United States); Frankignoul, Claude [Universite Pierre et Marie Curie-Paris 6, LOCEAN/IPSL, Paris Cedex 05 (France); Li, Laurent Z.X. [Universite Pierre et Marie Curie-Paris 6, LMD/IPSL, Paris Cedex 05 (France)

2011-04-15

The atmospheric circulation response to decadal fluctuations of the Atlantic meridional overturning circulation (MOC) in the IPSL climate model is investigated using the associated sea surface temperature signature. A SST anomaly is prescribed in sensitivity experiments with the atmospheric component of the IPSL model coupled to a slab ocean. The prescribed SST anomaly in the North Atlantic is the surface signature of the MOC influence on the atmosphere detected in the coupled simulation. It follows a maximum of the MOC by a few years and resembles the model Atlantic multidecadal oscillation. It is mainly characterized by a warming of the North Atlantic south of Iceland, and a cooling of the Nordic Seas. There are substantial seasonal variations in the geopotential height response to the prescribed SST anomaly, with an East Atlantic Pattern-like response in summer and a North Atlantic oscillation-like signal in winter. In summer, the response of the atmosphere is global in scale, resembling the climatic impact detected in the coupled simulation, albeit with a weaker amplitude. The zonally asymmetric or eddy part of the response is characterized by a trough over warm SST associated with changes in the stationary waves. A diagnostic analysis with daily data emphasizes the role of transient-eddy forcing in shaping and maintaining the equilibrium response. We show that in response to an intensified MOC, the North Atlantic storm tracks are enhanced and shifted northward during summer, consistent with a strengthening of the westerlies. However the anomalous response is weak, which suggests a statistically significant but rather modest influence of the extratropical SST on the atmosphere. The winter response to the MOC-induced North Atlantic warming is an intensification of the subtropical jet and a southward shift of the Atlantic storm track activity, resulting in an equatorward shift of the polar jet. Although the SST anomaly is only prescribed in the Atlantic ocean

The North Atlantic Ocean as habitat for Calanus finmarchicus: Environmental factors and life history traits

Science.gov (United States)

Melle, Webjørn; Runge, Jeffrey; Head, Erica; Plourde, Stéphane; Castellani, Claudia; Licandro, Priscilla; Pierson, James; Jonasdottir, Sigrun; Johnson, Catherine; Broms, Cecilie; Debes, Høgni; Falkenhaug, Tone; Gaard, Eilif; Gislason, Astthor; Heath, Michael; Niehoff, Barbara; Nielsen, Torkel Gissel; Pepin, Pierre; Stenevik, Erling Kaare; Chust, Guillem

2014-12-01

Here we present a new, pan-Atlantic compilation and analysis of data on Calanus finmarchicus abundance, demography, dormancy, egg production and mortality in relation to basin-scale patterns of temperature, phytoplankton biomass, circulation and other environmental characteristics in the context of understanding factors determining the distribution and abundance of C. finmarchicus across its North Atlantic habitat. A number of themes emerge: (1) the south-to-north transport of plankton in the northeast Atlantic contrasts with north-to-south transport in the western North Atlantic, which has implications for understanding population responses of C. finmarchicus to climate forcing, (2) recruitment to the youngest copepodite stages occurs during or just after the phytoplankton bloom in the east whereas it occurs after the bloom at many western sites, with up to 3.5 months difference in recruitment timing, (3) the deep basin and gyre of the southern Norwegian Sea is the centre of production and overwintering of C. finmarchicus, upon which the surrounding waters depend, whereas, in the Labrador/Irminger Seas production mainly occurs along the margins, such that the deep basins serve as collection areas and refugia for the overwintering populations, rather than as centres of production, (4) the western North Atlantic marginal seas have an important role in sustaining high C. finmarchicus abundance on the nearby coastal shelves, (5) differences in mean temperature and chlorophyll concentration between the western and eastern North Atlantic are reflected in regional differences in female body size and egg production, (6) regional differences in functional responses of egg production rate may reflect genetic differences between western and eastern populations, (7) dormancy duration is generally shorter in the deep waters adjacent to the lower latitude western North Atlantic shelves than in the east, (8) there are differences in stage-specific daily mortality rates between