Consulta: subjectFacets:"North Atlantic Ocean"
Registros recuperados: 21
Data/hora: 01/06/2024 03:43:48

Locations and mechanisms of ocean ventilation in the high-latitude North Atlantic in an eddy-permitting ocean model
Provedor de dados: 5
Autores: Macgilchrist, Graeme A.; Johnson, Helen L.; Marshall, David P.; Lique, Camille; Thomas, Matthew; Jackson, Laura C.; Wood, Richard A.
A substantial fraction of the deep ocean is ventilated in the high-latitude North Atlantic. Consequently, the region plays a crucial role in transient climate change through the uptake of carbon dioxide and heat. However, owing to the Lagrangian nature of the process, many aspects of deep Atlantic Ocean ventilation and its representation in climate simulations remain obscure. We investigate the nature of ventilation in the high latitude North Atlantic in an eddy-permitting numerical ocean circulation model using a comprehensive set of Lagrangian trajectory experiments. Backwards-in-time trajectories from a model-defined ‘North Atlantic DeepWater’ (NADW) reveal the locations of subduction from the surface mixed layer at high spatial resolution. The major...
Tipo: Text
Palavras-chave: North Atlantic Ocean; Atmosphere-ocean interaction; Lagrangian circulation/transport; Ocean circulation; Boundary currents; Diapycnal mixing.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00646/75833/76825.pdf

Geographical differences in habitat relationships of cetaceans across an ocean basin
Provedor de dados: 5
Autores: Mannocci, Laura; Roberts, Jason J.; Pedersen, Eric J.; Halpin, Patrick N.
The distributions of highly mobile marine species such as cetaceans are increasingly modeled at basin scale by combining data from multiple regions. However, these basin‐wide models often overlook geographical variations in species habitat relationships between regions. We tested for geographical variations in habitat relationships for a suite of cetacean taxa between the two sides of the North Atlantic basin. Using cetacean visual survey data and remote sensing data from the western and eastern basin in summer, we related the probability of presence of twelve cetacean taxa from three guilds to seafloor depth, sea surface temperature and primary productivity. In a generalized additive model framework, we fitted 1) basin‐wide (BW) models, assuming a single...
Tipo: Text
Palavras-chave: Environmental predictors; Geographical variation; Habitat relationships; Highly mobile marine species; North Atlantic Ocean; Species distribution modeling.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00630/74163/73721.pdf

Interannual variability of the Subpolar Mode Water properties over the Reykjanes Ridge during 1990-2006
Provedor de dados: 5
Autores: Thierry, Virginie; De Boisseson, Eric; Mercier, Herle.
Combining hydrographic data from the OVIDE (Observatoire de la Variabilité Interannuelle à Decennale/Observatory of the Interannual to Decadal Variability) section (Greenland-Portugal) with Argo and historical CTD data over the period 1990–2006, we estimate the variability of the core properties of a variety of Subpolar Mode Water (SPMW) observed on the eastern flank of the Reykjanes Ridge. This SPMW acquires its core properties in the winter mixed layer along the eastern side of the Reykjanes Ridge. We find that the February sea surface temperature along the ridge is a proxy for its core temperature. The sources of this mode water are water masses advected by the mean cyclonic circulation in the Iceland Basin. A density compensated tendency for cooling...
Tipo: Text
Palavras-chave: North Atlantic Oscillation; Subpolar mode water; North Atlantic Ocean.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2007/publication-3487.pdf

On the Movements of the North Atlantic Subpolar Front in the Preinstrumental Past*
Provedor de dados: 5
Autores: Marchal, Olivier; Waelbroeck, Claire; Colin De Verdiere, Alain.
Three sediment records of sea surface temperature (SST) are analyzed that originate from distant locations in the North Atlantic, have centennial-to-multicentennial resolution, are based on the same reconstruction method and chronological assumptions, and span the past 15 000 yr. Using recursive least squares techniques, an estimate of the time-dependent North Atlantic SST field over the last 15 kyr is sought that is consistent with both the SST records and a surface ocean circulation model, given estimates of their respective error (co)variances. Under the authors' assumptions about data and model errors, it is found that the 10 degrees C mixed layer isotherm, which approximately traces the modern Subpolar Front, would have moved by ~15 degrees of...
Tipo: Text
Palavras-chave: Inverse methods; Kalman filters; Climate variability; Circulation/ Dynamics; Geographic location/entity; Oceanic variability; Variability; Mathematical and statistical techniques; Fronts; North Atlantic Ocean.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00318/42922/42423.pdf

Foraminiferal δ18O reveals gas hydrate dissociation in Arctic and North Atlantic ocean sediments
Provedor de dados: 5
Autores: Dessandier, Pierre-antoine; Borrelli, Chiara; Yao, Haoyi; Sauer, Simone; Hong, Wei-li; Panieri, Giuliana.
Paleoceanographic investigations in the Arctic and north Atlantic are crucial to understanding past and current climate change, in particular considering amounts of pressure-temperature sensitive gas stored in marine sediments of the region. Many paleoceanographic studies are based on foraminiferal oxygen and carbon stable isotope compositions (δ18O, δ13C) from either planktonic specimens, benthic specimens or both. However, in seafloor regions promixal to high upward methane fluxes, such as where seafloor gas emission and shallow gas hydrate-bearing sediment occur, foraminiferal δ18O and δ13C display a wide range of values. Our study focuses on foraminiferal stable isotope signatures in shallow sediment at core sites in the Arctic and North Atlantic...
Tipo: Text
Palavras-chave: Foraminiferal stable isotopes; Gas hydrates; Authigenic carbonates Arctic Ocean; North Atlantic Ocean.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00610/72215/71338.pdf

Influence des ondes de Rossby sur le système biogéochimique de l'Océan Atlantique Nord: Utilisation des données satellites couleur de l'eau et d'un modèle couplé physique/biogéochimie
Provedor de dados: 5
Autores: Charria, Guillaume.
The marine phytoplankton in the ocean represents only less than 1% of global biomass. Phytoplankton performs half of all photosynthesis. This autotrophic biomass in ocean is then an essential element in the climate regulation through processes as carbon dioxide absorption during the photosynthesis. Therefore, we need to estimate precisely this biomass as well as the processes which affect it. Using remotely sensed data (altimetry and ocean colour) and a coupled physical/biogeochemical model (MERCATOR-OPA/NPZDDON), Rossby waves and their influence on phytoplankton biomass are specifically studied in the North Atlantic Ocean. Their features and their influences on surface chlorophyll concentrations were analysed. Through the different mechanisms identified,...
Tipo: Text
Palavras-chave: Coupled physical/biogeochemical modelling; Multi sensor wavelet analysis; Ocean carbon cycle; North Atlantic Ocean; Primary production; Ocean colour; Altimetry; Rossby (or planetary) waves; Planetary waves; Coupled physical/biogeochemical oceanography; Modélisaiton couplée physique/biogéochimie; Analyse en ondelettes multi capteurs; Cycle océanique du carbone; Océan Atlantique Nord; Production primaire; Couleur de l'eau; Altimétrie; Ondes de Rossby ou planétaires; Océanographie couplée physique/biogéochimie.
Ano: 2005
URL: http://archimer.ifremer.fr/doc/2005/these-2454.pdf

Mesoscale variability from a high-resolution model and from altimeter data in the North Atlantic Ocean
Provedor de dados: 5
Autores: Brachet, Sidonie; Le Traon, Pierre-yves; Le Provost, Christian.
The objective of the paper is to analyze the degree of realism of the Parallel Ocean Program ( POP) model of the Los Alamos Laboratory using the combined TOPEX/Poseidon and ERS-1/2 (TPERS) sea level anomaly (SLA) data sets and to present a detailed study of mesoscale characteristics in the North Atlantic. This description spans 8 years of data from 1993 to 2000. At first, we focus on the analysis of the mean eddy kinetic energy ( EKE) and show that the major characteristics of mesoscale variability are realistically simulated despite an overestimation of the EKE model in the Gulf Stream region. We then describe the SLA space and timescales and propagation velocities at a resolution never achieved before. There is a high level of agreement between the model...
Tipo: Text
Palavras-chave: Eddy kinetic energy; North Atlantic Ocean.
Ano: 2004
URL: http://archimer.ifremer.fr/doc/00087/19841/17491.pdf

Black scabbardfish, Aphanopus carbo, in the northeast Atlantic: distribution and hypothetical migratory cycle
Provedor de dados: 5
Autores: Farias, Ines; Morales-nin, Beatriz; Lorance, Pascal; Figueiredo, Ivone.
The biology, ecology, and dynamics of the deep-sea teleost black scabbardfish in the northeast Atlantic are reviewed. The black scabbardfish is a commercial bathypelagic species found in the NE Atlantic mostly from Iceland to the Canary Islands and Western Sahara, at depths from 800 to 1300 m. The spatial structure of its population is still uncertain, although the existence of one single stock that migrates around the NE Atlantic driven by feeding and reproduction is the most likely hypothesis consistent with available data. This review is based on data from commercial fisheries off the Faroe Islands, Hatton Bank, the west of the British Isles, and Portugal (mainland, Azores, and Madeira) and from Icelandic and Scottish scientific surveys collected...
Tipo: Text
Palavras-chave: Deep-water longline fisheries; Migration; Life cycle; Trichiuridae; Aphanopus carbo; North Atlantic Ocean.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00175/28636/27058.pdf

Observations of Irminger Sea Anticyclonic Eddies
Provedor de dados: 5
Autores: Fan, Xue; Send, Uwe; Testor, Pierre; Karstensen, Johannes; Lherminier, Pascale.
Mesoscale anticyclonic eddies in the Irminger Sea are observed using a mooring and a glider. Between 2002 and 2009, the mooring observed 53 anticyclones. Using a kinematic model, objective estimates of eddy length scales and velocity structure are made for 16 eddies. Anticyclones had a mean core diameter of 12 km, and their mean peak observed azimuthal speed was 0.1 m s(-1). They had core salinities and potential temperatures of 34.91-34.98 and 4.488-5.34 degrees C, respectively, making them warm and salty features. These properties represent a typical salinity anomaly of 0.03 and a temperature anomaly of 0.28 degrees C from noneddy values. All eddies had small (&lt;&lt; 1) Rossby numbers. In 2006, the glider observed two anticyclones having diameters of...
Tipo: Text
Palavras-chave: North Atlantic Ocean; Eddies; Mesoscale processes.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00137/24832/22921.pdf

Cyclones and Anticyclones in Seismic Imaging
Provedor de dados: 5
Autores: Barbosa Aguiar, A. C.; Menesguen, Claire; Le Gentil, Sylvie; Schopp, Richard; Carton, Xavier.
Nearly all the subsurface eddies detected in seismic imaging of sections in the northeast Atlantic have been assumed to be anticyclones containing Mediterranean Water (MW). Fewer MW cyclones have been observed and studied. In this study, the work of previous numerical studies is extended to investigate some characteristics of layering surrounding MW cyclones, using a primitive equation model with equal diffusivities for salinity and temperature to suppress the effects of double diffusion. It is shown that, after a stable state is reached, both anticyclones and cyclones display similar patterns of layering: stacked thin layers of high acoustic reflectivity located above and below the core of each vortex, which do not match isopycnals. The authors conclude...
Tipo: Text
Palavras-chave: Geographic location/entity; North Atlantic Ocean; Circulation/ Dynamics; Small scale processes; Atm/Ocean Structure/ Phenomena; Eddies; Vortices; Observational techniques and algorithms; Acoustic measurements/effects; Models and modeling; Primitive equations model.
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00281/39190/37746.pdf

Late Holocene oceanographic and climate change from the western European margin: the results of the HOLSMEER project
Provedor de dados: 5
Autores: Scourse, James; Sejrup, Hans Petter; Jones, Phil D.
The underlying aim of the HOLSMEER project has been to improve our understanding of natural climate variability through the search for, interpretation and quantification of, climatic variability in very high-resolution shallow marine records from Atlantic Europe covering the last 2000 years. This has been achieved through detailed analyses of a series of coastal and shallow marine sites spanning the Atlantic seaboard from Iberia to western Norway, and extending across to Iceland. HOLSMEER partners have documented pronounced instability in the thermohaline circulation (THC) during the period immediately prior to the recent significant anthropogenic impact on the environment. For the first time we have been able to document that these changes in the coastal...
Tipo: Text
Palavras-chave: Holocene; Palaeoclimate; Marine; Thermohaline circulation; Sea level; Arctica islandica; Transfer function; HOLSMEER project; North Atlantic Ocean; Western European margin.
Ano: 2006
URL: https://archimer.ifremer.fr/doc/00234/34504/33458.pdf

Frequency-dependent noise sources in the North Atlantic Ocean
Provedor de dados: 5
Autores: Sergeant, Amandine; Stutzmann, Eleonore; Maggi, Alessia; Schimmel, Martin; Ardhuin, Fabrice; Obrebski, Mathias.
[1] Secondary microseisms are the most energetic waves in the noise spectra between 3 and 10 s. They are generated by ocean wave interactions and are predominantly Rayleigh waves. We study the associated noise sources in the North Atlantic Ocean by coupling noise polarization analysis and source mapping using an ocean wave model that takes into account coastal reflections. From the Rayleigh wave polarization analysis, we retrieve the back azimuth to the noise sources in the time-frequency domain. Noise source modeling enables us to locate the associated generation areas at different times and frequencies. We analyze the distribution of secondary microseism sources in the North Atlantic Ocean using 20 broadband stations located in the Arctic and around the...
Tipo: Text
Palavras-chave: Noise sources; Secondary microseism; North Atlantic Ocean; Polarization.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00169/28075/26290.pdf

On the Mediterranean Water Composition
Provedor de dados: 5
Autores: Carracedo, Lidia; Pardo, P. C.; Flecha, S.; Perez, Ff.
The Mediterranean Outflow Water (MOW) spills from the Mediterranean Sea (east North Atlantic basin) west off the Strait of Gibraltar. As MOW outflows, it entrains eastern North Atlantic Central Waters (ENACW) and Intermediate Waters to form the neutrally buoyant Mediterranean Water (MW) that can be traced over the entire North Atlantic basin. Its high salinity content influences the thermohaline properties of the intermediate-deep water column in the North Atlantic and its dynamics. Here, the composition of MW in its source region (the Gulf of Cadiz, west off Strait of Gibraltar) is investigated on the basis of an optimum multiparameter analysis. The results obtained indicate that mixing of MOW (34.1% +/- 0.3%) occurs mainly with overlying ENACW (57.1% +/-...
Tipo: Text
Palavras-chave: Water masses; Geographic location/entity; Physical Meteorology and Climatology; North Atlantic Ocean; Entrainment; Circulation/ Dynamics; Mixing; Atm/Ocean Structure/ Phenomena; Climatology.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00629/74110/73547.pdf

Tephra horizons identified in the western North Atlantic and Nordic Seas during the Last Glacial Period: Extending the marine tephra framework
Provedor de dados: 5
Autores: Rutledal, Sunniva; Berben, Sarah M.p.; Dokken, Trond M.; Van Der Bilt, Willem G.m.; Cederstrøm, Jan Magne; Jansen, Eystein.
Geochemically distinct volcanic ash (tephra) deposits are increasingly acknowledged as a key geochronological tool to synchronize independent paleoclimate archives. Recent advances in the detection of invisible (crypto) tephra have led to the ongoing establishment, development and integration of regional tephra lattices. These frameworks offer an overview of the spatial extent of geochemically characterized tephra from dated eruptions – a valuable tool for precise correlation of paleorecords within these areas. Here, we harness cryptotephra analysis to investigate the occurrence of two well-known tephra markers from the Last Glacial Period (i.e. FMAZ II-1 (26.7 ka b2k) and NAAZ II (II-RHY-1) (55.3 ka b2k)), in marine sediment cores from the Nordic,...
Tipo: Text
Palavras-chave: Tephrochronology; Cryptotephra Tephrostratigraphy; Tephra isochrons; FMAZ II; NAAZ II; Geochemistry; Paleoceanography; Marine sediment cores Quaternary; North Atlantic Ocean.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00614/72659/71665.pdf

ISOW spreading and mixing as revealed by Deep‐Argo floats launched in the Charlie Gibbs Fracture Zone
Provedor de dados: 5
Autores: Racape, V.; Thierry, Virginie; Mercier, Herle; Cabanes, Cecile.
To improve our understanding of deep circulation, we deployed five Deep‐Argo floats (0–4000 m) in the Charlie Gibbs Fracture Zone (CGFZ), which channels the flow of Iceland‐Scotland Overflow Water (ISOW), a dense water mass of the North Atlantic Ocean. The floats were programmed to drift at 2750 dbar in the ISOW layer. The floats mainly moved westward in the CGFZ, although some of them followed different routes for few cycles depending on northward intrusions of the North Atlantic Current (NAC) over the CGFZ. One float revealed a direct route for ISOW from CGFZ to the Deep Western Boundary Current at Flemish Cap. In the CGFZ, oxygen data acquired by the floats revealed that the ISOW layer, characterized by salinity higher than 34.94 and density greater...
Tipo: Text
Palavras-chave: North Atlantic Ocean; Deep circulation; Deep-Argo float; Mixing; North Atlantic Current; Iceland-Scotland Overflow Water.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00513/62428/66710.pdf

A Middle Pleistocene Northeast Atlantic coccolithophore record: Paleoclimatology and paleoproductivity aspects
Provedor de dados: 5
Autores: Amore, F. O.; Flores, J. A.; Voelker, A. H. L.; Lebreiro, S. M.; Palumbo, E.; Sierro, F. J.
Changes in paleoclimate and paleoproductivity patterns have been identified by analysing, in conjunction with other available proxy data, the coccolithophore assemblages from core MD03-2699, located in the Portuguese margin in the time interval from the Marine Isotope Stage (MIS) 13/14 boundary to MIS 9 (535 to 300 ka). During the Mid-Brunhes event, the assemblages associated with the eccentricity minima are characterised by higher nannoplankton accumulation rate (NAR) values and by the blooming of the opportunistic genus Gephyrocapsa. Changes in coccolithophore abundance are also related to glacial-interglacial cycles. Higher NAR and numbers of coccoliths/g mainly occurred during the interglacial periods, while these values decreased during the glacial...
Tipo: Text
Palavras-chave: North Atlantic Ocean; Mid-Pleistocene; Coccolithophores; Paleoclimate; Paleoproductivity.
Ano: 2012
URL: https://archimer.ifremer.fr/doc/00092/20286/17946.pdf

Report on the CANCAP-Project for Marine Biological research in the Canarian - Cape Verdean Region of the North Atlantic Ocean (1976-1986). Part I. List of stations
Provedor de dados: 16
Autores: Land, J. van der.
A list of stations is given of the CANCAP-project for marine zoological, botanical and paleontological research in the southeastern part of the North Atlantic Ocean. This project included oceanographic expeditions as well as fieldwork on the islands and the coast of WestAfrica in the period from 1976 to 1986.
Tipo: Article / Letter to the editor
Palavras-chave: Marine biology; Marine biogeography; North Atlantic Ocean; Madeira archi- pelago; Azores; Selvagens archipelago; Canary Islands; Cape Verde Islands; Senegal; Mauritania.; 42.94.
Ano: 1987
URL: http://www.repository.naturalis.nl/record/317655

Barriers in the pelagic: population structuring of Calanus helgolandicus and C. euxinus in European waters
Provedor de dados: 16
Autores: Yebra, L.; Bonnet, D.; Harris, R.P.; Lindeque, P.K.; Peijnenburg, K.T.C.A.
Molecular studies of marine plankton have shown that ecological and/or environmental barriers play an important role in separating populations. Calanoid copepods are central in marine ecosystems, and dramatic biogeographical shifts in copepod assemblages associated with recent climate warming have been reported. We examined spatial population structuring in European waters of the Atlantic Ocean and Mediterranean Sea of Calanus helgolandicus and its sister species, C. euxi nus, from the Black Sea based on genetic and morphometric characters. The aims were to identify barriers to dispersal, relate these to hydrographic characteristics and infer historical patterns of distribution and demography. We analysed a 408 bp fragment of the mitochondrial 16S gene...
Tipo: Article / Letter to the editor
Palavras-chave: Calanus helgolandicus; Calanus euxinus; 16S rDNA; Mediterranean Sea; North Atlantic Ocean; Black Sea; 42.74.
Ano: 2011
URL: http://www.repository.naturalis.nl/record/470574

Macaronesian Pycnogonida
Provedor de dados: 16
Autores: Stock, J.H.
Thirty-two species of Pycnogonida are recorded from the region enclosed by the Azores, Cape Verde Islands and Mauritania, in depths between 0 and 3100 m. Of these, four are new: Eurycyde diacantha, Achelia tenuipes, Achelia turba, and Nymphon curvidens. The ranges of nine species are enlarged.
Tipo: Article / Letter to the editor
Palavras-chave: Pycnogonida; Taxonomy; Marine zoogeography; North Atlantic Ocean; Macaronesia; 42.74.
Ano: 1990
URL: http://www.repository.naturalis.nl/record/318876

Report on a shore collecting trip to the Azores (12 September-1 November 1979), including a list of collecting stations [CANCAP-Project]
Provedor de dados: 16
Autores: Hartog, J.C. den; Lavaleye, M.S.S.
Tipo: Article / Letter to the editor
Palavras-chave: Oceanography; Zoogeography; Taxonomy; Collecting stations; Faunistic assemblages; List; Canary Islands; Archipelago of Cape Verde; Archipelago of Madeira; Archipelago of the Azores; North Africa; North Atlantic Ocean; CANCAP-Project.
Ano: 1981
URL: http://www.repository.naturalis.nl/record/658993

Pyramidellidae (Mollusca, Gastropoda, Heterobranchia) collected during the Dutch CANCAP and MAURITANIA expeditions in the south-eastern part of the North Atlantic Ocean (part 2)
Provedor de dados: 16
Autores: Aartsen, J.J. van; Gittenberger, E.; Goud, J.
The species of the Pyramidellidae collected during several expeditions in the south-eastern part of the North Atlantic Ocean are listed, with locality data, depth ranges, and notes on nomenclature, systematics and distribution. The samples classified with the genera Eulimella (partly), Anisocycla, Syrnola, Chrysallida and Odostomella are dealt with in this paper. In total 70 species are reported from the research area, 24 of which are described as new to science. A lectotype of Obeliscus gracillima Smith, 1872 (= Eulimella variabilis de Folin, 1870) and neotypes of Chrysallida multicostata (Jeffreys, 1884) and Jaminia obtusa Brown, 1827, are designated.
Tipo: Article / Letter to the editor
Palavras-chave: Pyramidellidae; New species; North Atlantic Ocean; 42.73.
Ano: 2000
URL: http://www.repository.naturalis.nl/record/215732