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| Registros recuperados: 44 | |
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| Ndoye, S; Capet, Xavier; Estrade, Philippe; Machu, Eric; Kounta, L; Sow, B; Diakhate, M; Gayet, At. |
| The regional ocean circulation along the Southern Senegal shelf is studied using a numerical model for varying forcing fields during the upwelling season (November-May). The main objective is to study the shelf circulation of the marine environment in the Southern Senegal Upwelling Shelf (SSUS), the Lagrangian pathways by which waters are transported to the surface in the upwelling tongue and the fate of these waters. Model results are compared with hydrographic measurements during UPSEN2-ECOAO survey and satellite images datasets. The upwelling source waters and also the warm nearshore waters are analyzed, from a Lagrangian point of view, by computing the paths of particles that are passively advected by the regional ocean model velocity field (ROMS). It... |
| Tipo: Text |
Palavras-chave: Upwelling; Ocean circulation; Modeling; Coastal dynamics; Shelf; ROMS.. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00472/58346/60900.pdf |
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| Broecker, Wallace; Clark, Elizabeth; Barker, Stephen; Hajdas, Irena; Bonani, Georges; Moreno, Eva. |
| Radiocarbon age differences for pairs of coexisting late glacial age benthic and planktic foraminifera shells handpicked from 10 sediment samples from a core from a depth of 2.8 km in the western equatorial Pacific are not significantly different from that of 1600 years calculated from measurements on prenuclear seawater. This places a lower limit on the depth of the interface for the hypothetical radiocarbon-depleted glacial age seawater reservoir required to explain the 190% drop in the (14)C/C for atmospheric CO(2), which occurred during the mystery interval (17.5 to 14.5 calendar years ago). These measurements restrict the volume of this reservoir to be no more than 35% that of the ocean. Further, (14)C measurements on a single Last Glacial Maximum age... |
| Tipo: Text |
Palavras-chave: Ocean circulation; Mystery interval; Radiocarbon dating. |
| Ano: 2007 |
URL: https://archimer.ifremer.fr/doc/00233/34449/32884.pdf |
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| Morrow, Rosemary; Le Traon, Pierre-yves. |
| The paper provides a review of recent results on mesoscale ocean dynamics derived from satellite altimetry. Since 1992, we have had an unprecedented 18 year high-resolution monitoring of the ocean mesoscale field. Altimetry is often used in mesoscale studies in synergy with other remote sensing techniques and in situ data. This global, high-resolution data set has allowed oceanographers to quantify the previously unknown seasonal and interannual variations in eddy kinetic energy and eddy heat and salt transports, and investigate their causes. Eddy tracking techniques have allowed us to monitor their propagation pathways, to bring to light the meridional divergence of cyclones and anticyclones, and to question the role of Rossby waves versus non-linear... |
| Tipo: Text |
Palavras-chave: Satellite altimetry; Mesoscale eddies; Ocean circulation. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00087/19847/17767.pdf |
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| Van Sebille, Erik; Griffies, Stephen M.; Abernathey, Ryan; Adams, Thomas P.; Berloff, Pavel; Biastoch, Arne; Blanke, Bruno; Chassignet, Eric P.; Cheng, Yu; Cotter, Colin J.; Deleersnijder, Eric; Doos, Kristofer; Drake, Henri F.; Drijfhout, Sybren; Gary, Stefan F.; Heemink, Arnold W.; Kjellsson, Joakim; Koszalka, Inga Monika; Lange, Michael; Lique, Camille; Macgilchrist, Graeme A.; Marsh, Robert; Adame, C. Gabriela Mayorga; Mcadam, Ronan; Nencioli, Francesco; Paris, Claire B.; Piggott, Matthew D.; Polton, Jeff A.; Ruehs, Siren; Shah, Syed H. A. M.; Thomas, Matthew; Wang, Jinbo; Wolfram, Phillip J.; Zanna, Laure; Zika, Jan D.. |
| Lagrangian analysis is a powerful way to analyse the output of ocean circulation models and other ocean velocity data such as from altimetry. In the Lagrangian approach, large sets of virtual particles are integrated within the three-dimensional, time-evolving velocity fields. Over several decades, a variety of tools and methods for this purpose have emerged. Here, we review the state of the art in the field of Lagrangian analysis of ocean velocity data, starting from a fundamental kinematic framework and with a focus on large-scale open ocean applications. Beyond the use of explicit velocity fields, we consider the influence of unresolved physics and dynamics on particle trajectories. We comprehensively list and discuss the tools currently available for... |
| Tipo: Text |
Palavras-chave: Ocean circulation; Lagrangian analysis; Connectivity; Particle tracking; Future modelling. |
| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00412/52324/53099.pdf |
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| Hufnagl, Marc; Payne, Mark; Lacroix, Genevieve; Bolle, Loes J.; Daewele, Ute; Dickey-collas, Mark; Gerkema, Theo; Huret, Martin; Janssen, Frank; Kreus, Markus; Paetsch, Johannes; Pohlmann, Thomas; Ruardij, Piet; Schrum, Corinna; Skogen, Morten D.; Tiessen, Meinard C. H.; Petitgas, Pierre; Van Beek, Jan K. L.; Van Der Veer, Henk W.; Callies, Ulrich. |
| Hydrodynamic Ocean Circulation Models and Lagrangian particle tracking models are valuable tools e.g. in coastal ecology to identify the connectivity between offshore spawning and coastal nursery areas of commercially important fish, for risk assessment and more for defining or evaluating marine protected areas. Most studies are based on only one model and do not provide levels of uncertainty. Here this uncertainty was addressed by applying a suite of 11 North Sea models to test what variability can be expected concerning connectivity. Different notional test cases were calculated related to three important and well-studied North Sea fish species: herring (Clupea harengus), and the flatfishes sole (Solea solea) and plaice (Pleuronectes platessa). For sole... |
| Tipo: Text |
Palavras-chave: Ocean circulation; Lagrangian approach; Variability; Marine protected areas; Renewable energy; Wind park; Model intercomparison; Ensemble. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00385/49660/50198.pdf |
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| Arzel, Olivier; Huck, Thierry. |
| A simplified coupled ocean-atmosphere model, consisting of a one-layer bidimensional ocean model and a one-layer unidimensional energy balance atmospheric model [J. Clim. 13 (2000) 232] is used to study the unstable interactions between zonal winds and ocean gyres. In a specific range of parameters, decadal variability is found. Anomalies, quite homogeneous zonally, show small-scale wavelength in latitude: perturbations emerge and grow at the southern limb of the intergyre boundary and propagate southward before decaying. The wind stress anomalies are proportional to the meridional gradient of the atmospheric temperature anomalies: this ratio acts as a positive amplification factor, as confirmed by a parameter sensitivity analysis. Assuming... |
| Tipo: Text |
Palavras-chave: Ocean atmosphere system; Air sea interaction; Air sea coupling; Ocean circulation. |
| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/2003/publication-647.pdf |
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| Shakun, Jeremy D. |
| This dissertation presents the results of statistical analyses of large climate datasets from two time intervals – the 20th century instrumental record and the proxy record of the last deglaciation – in order to understand the forcings and mechanisms of past climate variability. A longstanding question in climate dynamics concerns the origin of Pacific decadal variability (PDV). This issue is addressed by calculating the Southern Hemisphere equivalent of the Pacific Decadal Oscillation (PDO) index from Pacific sea surface temperature (SST) anomalies over the 20th century, which is found to be similar to its Northern Hemisphere counterpart. The Northern and Southern PDO indices both exhibit pronounced seasonality in autocorrelation with interannual... |
| Tipo: Text |
Palavras-chave: El Nino-Southern Oscillation; Pacific Decadal Oscillation; Paleoclimate; Deglaciation; Ocean circulation; Milankovitch; Greenhouse gases. |
| Ano: 2010 |
URL: https://archimer.ifremer.fr/doc/00495/60654/64151.pdf |
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| Friedrich, T.; Timmermann, A.; Stichel, T.; Pahnke, K.. |
| Over the past decade, records of the seawater neodymium isotopic composition (epsilon(Nd)) have become a widely used proxy to reconstruct changes in ocean circulation. Our study investigates the transient response of epsilon(Nd) to large-scale ocean circulation changes using an Earth system model of intermediate complexity. It is shown that a weakening of the North Atlantic Deep Water formation results in positive epsilon(Nd) anomalies in the Atlantic and the Pacific below 1000m water depth whereas variations in Antarctic Bottom Water production generate a Pacific-Atlantic dipole pattern of deep ocean epsilon(Nd) changes. Further experiments explore which ocean regions are suitable to record the temporal evolution of the overturning in the North Atlantic... |
| Tipo: Text |
Palavras-chave: Neodymium; Ocean circulation; Meridional overturning; Ocean modeling; Reconstruction. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00289/40055/39405.pdf |
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| Waelbroeck, C.; Skinner, L. C.; Labeyrie, L.; Duplessy, J. -c.; Michel, E.; Vazquez Riveiros, Natalia; Gherardi, J. M.; Dewilde, F.. |
| Well-dated benthic foraminifer oxygen isotopic records (delta O-18) from different water depths and locations within the Atlantic Ocean exhibit distinct patterns and significant differences in timing over the last deglaciation. This has two implications: on the one hand, it confirms that benthic delta O-18 cannot be used as a global correlation tool with millennial-scale precision, but on the other hand, the combination of benthic isotopic records with independent dating provides a wealth of information on past circulation changes. Comparing new South Atlantic benthic isotopic data with published benthic isotopic records, we show that (1) circulation changes first affected benthic delta O-18 in the 1000-2200 m range, with marked decreases in benthic delta... |
| Tipo: Text |
Palavras-chave: Atlantic Ocean; Benthic oxygen isotope; Last deglaciation; Ocean circulation. |
| Ano: 2011 |
URL: https://archimer.ifremer.fr/doc/00214/32517/31003.pdf |
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| De La Fuente, Maria; Calvo, Eva; Skinner, Luke; Pelejero, Carles; Evans, David; Mueller, Wolfgang; Povea, Patricia; Cacho, Isabel. |
| It has been shown that the deep Eastern Equatorial Pacific (EEP) region was poorly ventilated during the Last Glacial Maximum (LGM) relative to Holocene values. This finding suggests a more efficient biological pump, which indirectly supports the idea of increased carbon storage in the deep ocean contributing to lower atmospheric CO2 during the last glacial. However, proxies related to respired carbon are needed in order to directly test this proposition. Here we present Cibicides wuellerstorfi B/Ca ratios from Ocean Drilling Program Site 1240 measured by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) as a proxy for deep water carbonate saturation state ([CO32-], and therefore [CO32-]), along with C-13 measurements. In addition, the... |
| Tipo: Text |
Palavras-chave: Marine carbon cycle; Carbonate chemistry; Ocean circulation; Glacial-interglacial cycles; Soft-tissue pump efficiency; Seafloor calcite dissolution. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00497/60824/64598.pdf |
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| Hines, Sophia Katharine Vizza. |
| Glacial-interglacial cycles, occurring at a period of approximately 100,000 years, have dominated Earth's climate over the past 800,000 years. These cycles involve major changes in land ice, global sea level, ocean circulation, and the carbon cycle. While it is generally agreed that the ultimate driver of global climate is changes in insolation, glacial cycles do not look like insolation forcing. Notably, there is a highly non-linear warming response at 100,000 years to a relatively small forcing, implicating a more complicated system of biogeochemical and physical drivers. The ocean plays a pivotal role in glacial-interglacial climate through direct equator-to-pole transport of heat and its role in the carbon cycle. The deep ocean contains 60 times more... |
| Tipo: Text |
Palavras-chave: Paleoceanography; Oceanography; Climate change; Glacial cycles; Ocean circulation; Ocean dynamics. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00493/60447/63892.pdf |
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| Sokolov, Serguei; Rintoul, Stephen R.. |
| Maps of the gradient of sea surface height (SSH) and sea surface temperature (SST) reveal that the Antarctic Circumpolar Current (ACC) consists of multiple jets or frontal filaments. The braided and patchy nature of the gradient fields seems at odds with the traditional view, derived from hydrographic sections, that the ACC is made up of three continuous circumpolar fronts. By applying a nonlinear fitting procedure to 638 weekly maps of SSH gradient (del SSH), it is shown that the distribution of maxima in del SSH (i.e., fronts) is strongly peaked at particular values of absolute SSH (i.e., streamlines). The association between the jets and particular streamlines persists despite strong topographic and eddy - mean flow interactions, which cause the jets to... |
| Tipo: Text |
Palavras-chave: Jets; Currents; Sea surface temperature; Ocean circulation. |
| Ano: 2007 |
URL: https://archimer.ifremer.fr/doc/00235/34616/32952.pdf |
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| Skinner, Luke C.; Waelbroeck, Claire; Scrivner, Adam E.; Fallon, Stewart J.. |
| Recent theories for glacial-interglacial climate transitions call on millennial climate perturbations that purged the deep sea of sequestered carbon dioxide via a "bipolar ventilation seesaw." However, the viability of this hypothesis has been contested, and robust evidence in its support is lacking. Here we present a record of North Atlantic deep-water radiocarbon ventilation, which we compare with similar data from the Southern Ocean. A striking coherence in ventilation changes is found, with extremely high ventilation ages prevailing across the deep Atlantic during the last glacial period. The data also reveal two reversals in the ventilation gradient between the deep North Atlantic and Southern Ocean during Heinrich Stadial 1 and the Younger Dryas.... |
| Tipo: Text |
Palavras-chave: Ocean circulation; Carbon cycle; Abrupt change. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00290/40153/39327.pdf |
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| 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 |
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| Ferron, Bruno; Marotzke, Jochem. |
| World Ocean Circulation Experiment (WOCE) hydrographic sections and a sea-surface climatology are combined with a ocean general circulation model through a 4D-variational method to analyze the meridional overturning of the Indian Ocean. The regional model is run with realistic surface forcings over year 1995 for which most of WOCE Indian Ocean sections were made. The assimilation controls the initial temperature and salinity fields, surface forcings and open-boundary velocities, temperature and salinity. When no observations are assimilated, the model shows that the deep (below 1000 m) meridional overturning is weak compared to observation-based estimates. This is a common feature of general circulation models. In contrast, after the assimilation, the... |
| Tipo: Text |
Palavras-chave: Overturn; Oceanographic surveys; Hydrographic data; Ocean circulation. |
| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/2003/publication-582.pdf |
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| Registros recuperados: 44 | |
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