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Registros recuperados: 34
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A global inventory of small floating plastic debris ArchiMer
Van Sebille, Erik; Wilcox, Chris; Lebreton, Laurent; Maximenko, Nikolai; Hardesty, Britta Denise; Van Franeker, Jan A.; Eriksen, Marcus; Siegel, David; Galgani, Francois; Law, Kara Lavender.
Microplastic debris floating at the ocean surface can harm marine life. Understanding the severity of this harm requires knowledge of plastic abundance and distributions. Dozens of expeditions measuring microplastics have been carried out since the 1970s, but they have primarily focused on the North Atlantic and North Pacific accumulation zones, with much sparser coverage elsewhere. Here, we use the largest dataset of microplastic measurements assembled to date to assess the confidence we can have in global estimates of microplastic abundance and mass. We use a rigorous statistical framework to standardize a global dataset of plastic marine debris measured using surface-trawling plankton nets and coupled this with three different ocean circulation models...
Tipo: Text Palavras-chave: Marine debris; Ocean circulation; Model comparison.
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00309/42053/41349.pdf
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A numerical modeling study of the Southern Senegal upwelling shelf: Circulation and upwelling source waters ArchiMer
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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Analyzing Large Paleoclimate Datasets: Implications for Past and Future Climate Change. ArchiMer
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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ANDRO: An Argo-Based Deep Displacement Dataset ArchiMer
Ollitrault, Michel; Rannou, Jean Philippe.
During the first decade of the twenty-first century, more than 6000 Argo floats have been launched over the World Ocean, gathering temperature and salinity data from the upper 2000 m, at a 10-day or so sampling period. Meanwhile their deep displacements can be used to map the ocean circulation at their drifting depth (mostly around 1000 m). A comprehensive processing of the whole Argo dataset collected prior to 1 January 2010 has been performed to produce a world-wide dataset of deep displacements. This numerical atlas, named ANDRO, after a traditional dance of Brittany meaning a swirl, comprises some 600 000 deep displacements. These displacements, based on Argo or GPS surface locations only, have been fully checked and corrected for possible errors found...
Tipo: Text Palavras-chave: Lagrangian circulation/transport; Large-scale motions; Ocean circulation.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00138/24901/22994.pdf
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Atlantic Meridional Overturning Circulation during the Last Glacial and Deglacial: Inferences from the Atlantic Tropical Thermocline Temperature and Seawater Radiocarbon Activity ArchiMer
Huang, Enqing.
This thesis aims to investigate variations of the last glacial and deglacial Atlantic Ocean circulation, with emphasize on the Atlantic deepwater ventilation rate during the Last Glacial Maximum (LGM). The highlights of the thesis are as the followings: (1) the modern frontal zone between the North Atlantic and the South Atlantic central waters off NW Africa shifted to the south during the last glacial and deglacial time periods. (2) The radiocarbon-based circulation age of the deep Atlantic (> 1500 m) was estimated to be less than 400 years during the LGM, which was equal to or less than its pre-bomb value. Therefore, the LGM deep Atlantic was inferred to be well ventilated. (3) The abyssal Atlantic (below 2500 m) prior to the LGM was more depleted in...
Tipo: Text Palavras-chave: Climate change; Ocean circulation; Atlantic Ocean; Glacial; Deglacial; Thermocline; Radiocarbon; Global carbon cycle; Foraminifera; Carbonate; Trace elements; Deep ocean ventilation rates.
Ano: 2013 URL: https://archimer.ifremer.fr/doc/00493/60446/63891.pdf
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Available Potential Energy in Density Coordinates ArchiMer
Colin De Verdiere, Alain; Huck, Thierry; Pogossian, Souren; Ollitrault, Michel.
The vertically integrated potential energy of an incompressible stratified fluid formulated in density coordinates can be simply written as a weighted vertical sum of the squares of the vertical displacements of density surfaces, a general expression valid for arbitrary displacements. The sum of this form of potential energy and kinetic energy is then a conserved quantity for the multilayer shallow water model. The formulation in density coordinates is a natural one to find the Lorenz reference state of available potential energy (APE).We describe the method to compute the APE of an ocean state and provide two applications. The first is the classical double-gyre, wind-driven circulation simulated by a shallow water model at high resolution.We show that the...
Tipo: Text Palavras-chave: Energy transport; Ocean circulation; Ocean dynamics; Isopycnal coordinates.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00464/57521/59707.pdf
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Can We Infer Diapycnal Mixing Rates from the World Ocean Temperature-Salinity Distribution? ArchiMer
Arzel, Olivier; Colin De Verdiere, Alain.
The turbulent diapycnal mixing in the ocean is currently obtained from microstructure and finestructure measurements, dye experiments, and inverse models. This study presents a new method that infers the diapycnal mixing from low-resolution numerical calculations of the World Ocean whose temperatures and salinities are restored to the climatology. At the difference of robust general circulation ocean models, diapycnal diffusion is not prescribed but inferred. At steady state the buoyancy equation shows an equilibrium between the large-scale diapycnal advection and the restoring terms that take the place of the divergence of eddy buoyancy fluxes. The geography of the diapycnal flow reveals a strong regional variability of water mass transformations....
Tipo: Text Palavras-chave: Diapycnal mixing; Eddies; Meridional overturning circulation; Mixing; Ocean circulation; General circulation models.
Ano: 2016 URL: https://archimer.ifremer.fr/doc/00600/71197/69563.pdf
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Challenges and Prospects in Ocean Circulation Models ArchiMer
Fox-kemper, Baylor; Adcroft, Alistair; Boening, Claus W.; Chassignet, Eric P.; Curchitser, Enrique; Danabasoglu, Gokhan; Eden, Carsten; England, Matthew H.; Gerdes, Ruediger; Greatbatch, Richard J.; Griffies, Stephen M.; Hallberg, Robert W.; Hanert, Emmanuel; Heimbach, Patrick; Hewitt, Helene T.; Hill, Christopher N.; Komuro, Yoshiki; Legg, Sonya; Le Sommer, Julien; Masina, Simona; Marsland, Simon J.; Penny, Stephen G.; Qiao, Fangli; Ringler, Todd D.; Treguier, Anne-marie; Tsujino, Hiroyuki; Uotila, Petteri; Yeager, Stephen G..
We revisit the challenges and prospects for ocean circulation models following Griffies et al. (2010). Over the past decade, ocean circulation models evolved through improved understanding, numerics, spatial discretization, grid configurations, parameterizations, data assimilation, environmental monitoring, and process-level observations and modeling. Important large scale applications over the last decade are simulations of the Southern Ocean, the Meridional Overturning Circulation and its variability, and regional sea level change. Submesoscale variability is now routinely resolved in process models and permitted in a few global models, and submesoscale effects are parameterized in most global models. The scales where nonhydrostatic effects become...
Tipo: Text Palavras-chave: Ocean circulation; Model; Parameterization; Climate; Ocean processes.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00488/59989/63213.pdf
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Circulación y estructura termohalina en una región del Pacífico Oriental (03°16'S-31°23'S) durante un período de El Niño 1997-1998 OceanDocs
Zambrano, E.; Garcés Vargas, J..
El objetivo del presente trabajo es estudiar la estructura termohalina superficial y subsuperficial de una región del Pacífico Sudeste (Guayaquil-Valparaíso), Fig. 1, durante el término de la primavera austral de 1997 para determinar los posibles cambios en la circulación. Para esta fecha se dio comienzo la VII Expedición Ecuatoriana a la Antártida a bordo del B/I ORION y simultáneamente se estaba desarrollando un evento ENOS de intensidad fuerte.
Tipo: Journal Contribution Palavras-chave: El Nino phenomena; Thermohaline circulation; Surface temperature; T/S diagrams; Current direction; Countercurrents; Current measurement; Ocean circulation.
Ano: 1998 URL: http://hdl.handle.net/1834/2316
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Circulation around La Reunion and Mauritius islands in the south-western Indian Ocean: A modeling perspective ArchiMer
Pous, Stephane; Lazure, Pascal; Andre, Gael; Dumas, Franck; Halo, Issufo; Penven, Pierrick.
Circulation around both islands is dominated by westward propagating features The predominant time scale of variability of currents and SSH is 60 days There is local generation of eddies in the lee of the islands due to topography
Tipo: Text Palavras-chave: Ocean circulation; Hydrodynamic model; La Reunion; Eddies; Rossby waves.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00195/30624/29073.pdf
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Corrientes en la plataforma continental OceanDocs
Piola, A.R.; Rivas, A..
In this chapter the main features of the currents on the Argentine continental shelf are described. Due to the scarcity of direct current observations, adequate to resolve the mean flow, the circulation of the continental shelf is studied based on property distributions and models. These analyses indicate that the mean flowover the continental shelf varies between 1 and 2 Sverdrups (1Sverdrup = 1x106 m3 s-1)towards the NNE. A synthesis of results of studies of higher frequency motions is also presented. The most relevant results derived from long term direct current observations on the continental shelf near 43°S are discussed. The mean current velocities in the inner and mid-shelf regions vary between 0,05 and 0,10 m/s towards the NNE, in agreement with...
Tipo: Book Section Palavras-chave: Continental shelves; Ocean currents; Ocean circulation; Physical oceanography; Ocean currents; Physical oceanography; Continental shelves; Http://aims.fao.org/aos/agrovoc/c_12883; Http://aims.fao.org/aos/agrovoc/c_5830; Http://aims.fao.org/aos/agrovoc/c_32413.
Ano: 1997 URL: http://hdl.handle.net/1834/1704
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Decadal oscillations in a simplified coupled model due to unstable interactions between zonal winds and ocean gyres ArchiMer
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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Distribución de las corrientes alrededor de las Islas Galápagos OceanDocs
Lucero, M..
De la información de corrientes, obtenidas en forma directa con un correntómetro ADCP WHS300, durante el Crucero Oceanográfico realizado desde el 31 de julio al 16 de agosto del 2000, se determinó el patrón de circulación alrededor de las Islas Galápagos, el mismo que no sigue estrictamente la distribución encontrada en forma global por otros autores. La circulación en el área de estudio está principalmente gobernada por la presencia de los fuertes afloramientos producidos al oeste de las islas, por la topografía submarina del Archipiélago y por la presencia de las derivas superficiales hacia el oeste, producto de la convergencia de las Corrientes Sur Ecuatorial y Corriente de Humboldt. Los mayores flujos fueron observados en los niveles superficiales en...
Tipo: Journal Contribution Palavras-chave: Current data; Oceanographic equipment; Cruises; Acoustic current meters; Oceanic islands; Ocean circulation; Coastal upwelling.
Ano: 2000 URL: http://hdl.handle.net/1834/2243
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Esquema de circulación del Golfo de Batabanó OceanDocs
Simanca, J.; Fernández, L.; Viamontes, J.; Ramírez, O.; Arriaza, L.; Ochoa, J.L..
Se modificó el patrón de circulación en la periferia acuática del Golfo de Batabanó a partir de la caracterización estadística de la corriente residual filtrada de series temporales provenientes de 12 estaciones correntométricas obtenidas de julio de 1988 a agosto de 1989. Para el filtraje de la componente no periódica se utilizó el filtro Doodson. Los resultados muestran que las corrientes residuales son débiles, con intensidades que variaron entre 1.2 - 5.5 cm/s como promedio por estaciones, además, las velocidades resultaron ser más estables en dirección que en intensidad. Se observó salida de agua por el extremo SE del golfo y por algunos canales al E de la Isla de la Juventud, y entrada de agua por el E del golfo en su límite con el Golfo de Cazones y...
Tipo: Conference Material Palavras-chave: Time series; Current measurement; Coastal currents; Ocean circulation.
Ano: 2006 URL: http://hdl.handle.net/1834/2230
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Estudio numérico de circulación océanica sobre la plataforma continental argentina OceanDocs
Sitz, L.E..
This dissertation analyses the barotropic and baroclinic response of the Argentinean Continental Shelf to different forcing using a three-dimensional numerical ocean model. The study aims towards a systematical exploration of the physical processes that control the circulation. To facilitate the dynamical understanding of the results our experimental strategy was to start with a three dimensional barotropic model (constant density) that examines the influence of winds and tides, and to progress to a more complex case including density stratification (baroclinic model). It was found that the average annual circulation, forced only by the wind, shows a strong contrast between the northern and southern region of the study area. A detailed analysis...
Tipo: Theses and Dissertations Palavras-chave: Numerical analysis; Water masses; Mathematical models; Physical oceanography; Current data; Tides; Winds; Ocean circulation; Physical oceanography; Tides; Winds; Mathematical models.
Ano: 2009 URL: http://hdl.handle.net/1834/3878
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Evolution of neodymium isotopic signature of seawater during the Late Cretaceous: Implications for intermediate and deep circulation ArchiMer
Moiroud, Mathieu; Puceat, Emmanuelle; Donnadieu, Yannick; Bayon, Germain; Guiraud, Michel; Voigt, Silke; Deconinck, Jean-francois; Monna, Fabrice.
Neodymium isotopic compositions (εNd) have been largely used for the last fifty years as a tracer of past ocean circulation, and more intensively during the last decade to investigate ocean circulation during the Cretaceous period. Despite a growing set of data, circulation patterns still remain unclear during this period. In particular, the identification of the deep-water masses and their spatial extension within the different oceanic basins are poorly constrained. In this study we present new deep-water εNd data inferred from the Nd isotope composition of fish remains and Fe-Mn oxyhydroxide coatings on foraminifera tests, along with new εNd data of residual (partly detrital) fraction recovered from DSDP sites 152 (Nicaraguan Rise), 258 (Naturaliste...
Tipo: Text Palavras-chave: Cretaceous; Neodymium isotopes; Ocean circulation; Southern Ocean.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00278/38962/37502.pdf
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Geostrophic Closure of the Zonally Averaged Atlantic Meridional Overturning Circulation ArchiMer
Sevellec, Florian; Huck, Thierry.
It is typically assumed that the meridional density gradient in the North Atlantic is well and positively correlated with the Atlantic meridional overturning circulation (AMOC). In numerical "water-hosing" experiments, for example, imposing an anomalous freshwater flux in the Northern Hemisphere leads to a slowdown of the AMOC. However, on planetary scale, the first-order dynamics are linked to the geostrophic balance, relating the north-south pressure gradient to the zonal circulation. In this study, these two approaches are reconciled. At steady state and under geostrophic dynamics, an analytical expression is derived to relate the zonal and meridional pressure gradient. This solution is only valid where the meridional density gradient length scale is...
Tipo: Text Palavras-chave: Meridional overturning circulation; Thermohaline circulation; Atm/Ocean Structure/ Phenomena; Ocean circulation; Baroclinic flows; Geographic location/entity; Ekman pumping; Circulation/ Dynamics; Atlantic Ocean.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00323/43456/42843.pdf
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Glacial Ocean Dynamics: Insight from Deep-Sea Coral Reconstructions and A Time-Dependent Dynamical Box Model ArchiMer
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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Global Temperature-Salinity Profile Programme (GTSPP) - Overview and Future OceanDocs
Wilson, J.R..
This document is directed to the scientific research community and users of operational ocean data. It is also intended to provide an example and be a source of information to programmes such as the Global Ocean Observing System (GOOS) for developing and implementing end-to-end data management systems. The document is also directed towards Member States of IOC. It discusses how Member States can make contributions and how they can benefit from the GTSPP.
Tipo: Report Palavras-chave: Oceanography; Temperature data; Temperature measurement; Ocean circulation; Salinity; Salinity data; Salinity measurement; Salinity profiles; Salinity scales; Salinity.
Ano: 1998 URL: http://hdl.handle.net/1834/2796
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Global Temperature-Salinity Profile Programme (GTSPP) - Overview and Future OceanDocs
Wilson, J.R..
This document is directed to the scientific research community and users of operational ocean data. It is also intended to provide an example and be a source of information to programmes such as the Global Ocean Observing System (GOOS) for developing and implementing end-to-end data management systems. The document is also directed towards Member States of IOC. It discusses how Member States can make contributions and how they can benefit from the GTSPP.
Tipo: Book Palavras-chave: Oceanography; Temperature data; Temperature measurement; Ocean circulation; Salinity; Salinity data; Salinity measurement; Salinity profiles; Salinity scales; Salinity; Http://aims.fao.org/aos/agrovoc/c_6751.
Ano: 1998 URL: http://hdl.handle.net/1834/2796
Registros recuperados: 34
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