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A Lagrangian analysis of the Indian-Atlantic interocean exchange in a regional model - art. no. L14611 ArchiMer
Doglioli, Andrea; Veneziani, M; Blanke, Bruno; Speich, Sabrina; Griffa, A.
We present a new numerical Lagrangian technique based on the coupling of transport computation with spin analysis of trajectories. This method was applied to results from a high-resolution numerical model of the oceanic region around South Africa. We estimated an Indian-Atlantic leakage of about 14 Sv. In the western Cape Basin, approximately 30% of this transport is due to trapping eddies with a ratio between cyclones and anticyclones transport of 1.3. These findings are briefly discussed with respect to recent observations of the highly nonlinear regime found in this area of the Cape Basin.
Tipo: Text Palavras-chave: Anticyclones transport; Cyclones transport; The Indian Atlantic interocean exchange; South Africa; Numerical model.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/publication-1847.pdf
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A Lagrangian Method to Isolate the Impacts of Mixed Layer Subduction on the Meridional Overturning Circulation in a Numerical Model ArchiMer
Thomas, Matthew; Treguier, Anne-marie; Blanke, Bruno; Deshayes, Julie; Voldoire, Aurore.
Large differences in the Atlantic meridional overturning circulation (AMOC) exhibited between the available ocean models pose problems as to how they can be interpreted for climate policy. A novel Lagrangian methodology has been developed for use with ocean models that enables a decomposition of the AMOC according to its source waters of subduction from the mixed layer of different geographical regions. The method is described here and used to decompose the AMOC of the Centre National de Recherches Météorologiques (CNRM) ocean model, which is approximately 4.5 Sv (1 Sv = 106 m3 s−1) too weak at 26°N, compared to observations. Contributions from mixed layer subduction to the peak AMOC at 26°N in the model are dominated by the Labrador Sea, which contributes...
Tipo: Text Palavras-chave: Circulation; Dynamics; Convection; Lagrangian circulation; Transport; Meridional overturning circulation; Atm; Ocean Structure; Phenomena; Oceanic mixed layer; Models and modeling; General circulation models.
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00284/39523/38016.pdf
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A Lagrangian numerical investigation of the origins and fates of the salinity maximum water in the Atlantic ArchiMer
Blanke, Bruno; Arhan, Michel; Lazar, A; Prevost, Gwenaelle; Blanke, Bruno; Arhan, Michel; Lazar, A; Prevost, Gwenaelle.
The origins and fates of the Atlantic salinity maximum water (SMW), formed through excess evaporation in the tropics and subtropics of both hemispheres, are studied using monthly mean outputs of a numerical simulation of the world ocean climatological circulation. After defining formation domains from the surface salinity field and the vertical stratification, a Lagrangian technique is used to estimate the formation rates and main pathways in each hemisphere and the role of this water in the framework of the warm water return flow of the meridional overturning cell. Formation rates around 9 and 11 Sv are found in the Southern and Northern Hemispheres, respectively. While the export of the southern SMW from its formation area is realized by the western...
Tipo: Text Palavras-chave: Atlantic ocean; Lagrangian method; Numerical simulation; Salinity; Sea water.
Ano: 2002 URL: https://archimer.ifremer.fr/doc/2002/publication-769.pdf
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A regional numerical ocean model of the circulation in the Bay of Biscay ArchiMer
Friocourt, Yann; Levier, Bruno; Speich, Sabrina; Blanke, Bruno; Drijfhout, S.
The seasonal circulation along the northern Iberian Peninsula and in the Bay of Biscay is investigated by means of a regional ocean model. In particular, the modeled velocities and tracers are compared to available observations and used to hypothesize what the circulation may look like in areas where the density of observations is scarcer. Despite a few biases in the thermohaline properties of some water masses, the model is able to represent the various water masses present in the region in an acceptable way. In particular, the density and depth ranges of most water masses are in good agreement with observed ranges. Similarly, the circulation schemes compare generally well with observations, both in annual mean as for the seasonal features. The model...
Tipo: Text
Ano: 2007 URL: https://archimer.ifremer.fr/doc/2007/publication-3024.pdf
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A surface “super-convergence” pathway connecting the South Indian Ocean to the subtropical South Pacific gyre ArchiMer
Maes, C.; Grima, N.; Blanke, Bruno; Martinez, E.; Paviet-salomon, T.; Huck, Thierry.
We study the dispersion and convergence of marine floating material by surface currents from a model reanalysis that represents explicitly mesoscale eddy variability. Lagrangian experiments about the long-term evolution (29 years) of an initially homogeneous concentration of particles are performed at global scale with horizontal current at ¼° resolution and refreshed daily over the 1985-2013 period. Results confirm and document the five known sites of surface convergence at the scale of individual oceanic basins, but also reveal a convergent pathway connecting the South Indian subtropical region with the convergence zone of the South Pacific through the Great Australian Bight, the Tasman Sea and the southwest Pacific Ocean. This “super-convergent” pathway...
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Ano: 2018 URL: http://archimer.ifremer.fr/doc/00425/53631/54461.pdf
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Anticyclonic eddies connecting the western boundaries of Indian and Atlantic oceans ArchiMer
Laxenaire, R.; Speich, S.; Blanke, Bruno; Chaigneau, A.; Pegliasco, C.; Stegner, A..
The Indo‐Atlantic interocean exchanges achieved by Agulhas Rings are tightly linked to global ocean circulation and climate. Yet, they are still poorly understood because they are difficult to identify and follow. We propose here an original assessment on Agulhas Rings, achieved by TOEddies, a new eddy identification and tracking algorithm that we applied over 24 years of satellite altimetry. Its main novelty lies in the detection of eddy splitting and merging events. These are particularly abundant and significantly impact the concept of a trajectory associated with a single eddy, which becomes less obvious than previously admitted. To overcome this complication, we have defined a network of segments that group together in relatively complex trajectories....
Tipo: Text Palavras-chave: Agulhas Rings; Eddy tracking; Interocean exchange; Mesoscale dynamics.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00463/57516/59682.pdf
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California Coastal Upwelling Onset Variability: Cross-Shore and Bottom-Up Propagation in the Planktonic Ecosystem ArchiMer
Chenillat, Fanny; Riviere, Pascal; Capet, Xavier; Franks, Peter J. S.; Blanke, Bruno.
The variability of the California Current System (CCS) is primarily driven by variability in regional wind forcing. In particular, the timing of the spring transition, i.e., the onset of upwelling-favorable winds, varies considerably in the CCS with changes in the North Pacific Gyre Oscillation. Using a coupled physical-biogeochemical model, this study examines the sensitivity of the ecosystem functioning in the CCS to a lead or lag in the spring transition. An early spring transition results in an increased vertical nutrient flux at the coast, with the largest ecosystem consequences, both in relative amplitude and persistence, hundreds of kilometers offshore and at the highest trophic level of the modeled food web. A budget analysis reveals that the...
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Ano: 2013 URL: http://archimer.ifremer.fr/doc/00146/25706/24010.pdf
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Displacements and transformations of nitrate-rich and nitrate-poor water masses in the tropical Pacific during the 1997 El Nino ArchiMer
Radenac, Marie-helene; Dandonneau, Yves; Blanke, Bruno.
A Lagrangian analysis was applied to the outputs of a coupled physical-biogeochemical model to describe the redistribution of nitrate-rich and nitrate-poor surface water masses in the tropical Pacific throughout the major 1997 El Nino. The same tool was used to analyze the causes of nitrate changes along trajectories and to investigate the consequences of the slow nitrate uptake in the high nutrient low chlorophyll (HNLC) region during the growth phase of the event. Three patterns were identified during the drift of water masses. The first mechanism is well known along the equator: oligotrophic waters from the western Pacific are advected eastward and retain their oligotrophic properties along their drift. The second concerns the persistent upwelling in...
Tipo: Text Palavras-chave: Lagrangian analysis; El Nino; Tropical Pacific; Nitrate uptake.
Ano: 2005 URL: http://archimer.ifremer.fr/doc/2005/publication-938.pdf
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Estimates of the mortality and the duration of the trans-Atlantic migration of European eel Anguilla anguilla leptocephali using a particle tracking model ArchiMer
Bonhommeau, Sylvain; Le Pape, O.; Gascuel, D.; Blanke, Bruno; Treguier, Anne-marie; Grima, Nicolas; Vermard, Youen; Castonguay, M.; Rivot, E..
Using Lagrangian simulations, based on circulation models over three different hydroclimatic periods in the last 45 years in the North Atlantic Ocean, the trans-Atlantic migration of the European eel Anguilla anguilla leptocephali was simulated via the passive drift of particles released in the spawning area. Three different behaviours were modelled: drifting at fixed depth, undergoing a vertical migration or choosing the fastest currents. Simulations included mortality hypotheses to estimate a realistic mean migration duration and relative survival of A. anguilla larvae. The mean migration duration was estimated as 21 months and the mortality rate as 3 center dot 8 per year, i.e. < 0 center dot 2% of A. anguilla larvae may typically survive the...
Tipo: Text Palavras-chave: Migration duration; Leptocephalus mortality; Lagrangian modelling.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/publication-6614.pdf
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Estimating the Lagrangian residual circulation in the Iroise Sea ArchiMer
Muller, Heloise; Blanke, Bruno; Dumas, Franck; Lekien, Francois; Mariette, Vincent.
In this study, the Lagrangian residual circulation in the Iroise Sea is estimated by a numerical method where the trajectories of the particles released in any given velocity field are calculated by a diagnostic tool. From their knowledge, the residual Lagrangian currents are computed over a whole number of M2 tidal cycles. The Lagrangian residual circulation is mapped from sea surface currents measured by HF radars and from the surface currents computed with the Model for Applications at Regional Scales (MARS), a regional 3D ocean model forced, here, by the Weather Research and Forecasting (WRF) regional meteorological model. In order to overcome inconvenient space- and time-variations in radar coverage, the measured radar data are interpolated,...
Tipo: Text Palavras-chave: High frequency radar data; Regional ocean modeling; Lagrangian residual circulation; Iroise Sea.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/publication-7324.pdf
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Estimating the wreckage location of the Rio-Paris af447 ArchiMer
Ollitrault, Michel; Blanke, Bruno; Chen, Changsheng; Diansky, Nicolai; Drevillon, Marie; Greiner, Eric; Lefevre, Fabien; Limeburner, Richard; Lezaud, Pascal; Louazel, Stéphanie; Nurser, George; Paradis, Denis; Scott, Robert.
Tipo: Text Palavras-chave: Current; Equator; Wind; RIO-PARIS AF447.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00027/13777/10915.pdf
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Extratropical sources of equatorial Pacific upwelling in an OGCM ArchiMer
Rodgers, Kb; Blanke, Bruno; Madec, G; Aumont, O; Ciais, P; Dutay, Jc.
The extratropical sources of equatorial undercurrent (EUC) water have been identified for an ocean circulation model using Lagrangian trajectory analysis. It has been found that the EUC waters emenate from a wide range of latitudes in the Pacific basin, with its densest constituent watermass being Subantarctic Mode Water (SAMW) from 50degreesS. Further analysis of the basin-scale circulation fields has revealed significant advective diapycnal mass fluxes associated with intergyre exchange. As a result of these diapycnal mass fluxes, the EUC transport as a function of density at 151degreesW (an Eulerian diagnostic) looks quite different from the original subduction rate as a function of density for the same collection of water particles. This implicates...
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Ano: 2003 URL: http://archimer.ifremer.fr/doc/00000/10613/9403.pdf
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From the western boundary currents to the Pacific Equatorial Undercurrent: Modeled pathways and water mass evolutions ArchiMer
Grenier, Melanie; Cravatte, Sophie; Blanke, Bruno; Menkes, Christophe; Koch-larrouy, Ariane; Durand, Fabien; Melet, Angelique; Jeandel, Catherine.
The hydrological and geochemical properties of the waters constituting the Pacific Equatorial Undercurrent (EUC) determine the properties of the equatorial cold tongue. Understanding and quantifying the various EUC origins is therefore of prime importance. For this purpose, a high-resolution (1/4 degrees) interannual oceanic simulation was analyzed from the western tropical Pacific boundaries to 140 degrees W, using a Lagrangian framework. Waters from the Low-Latitude Western Boundary Currents (LLWBCs) transiting from Vitiaz Strait (the main contributor), from Solomon Strait, and via the Mindanao Current were identified as the principal sources to the EUC. Waters conveyed by the interior ocean off equator are negligible till 180 E. The LLWBCs' waters...
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Ano: 2011 URL: http://archimer.ifremer.fr/doc/00060/17105/14621.pdf
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High-resolution atmospheric forcing for regional oceanic model: the Iroise Sea ArchiMer
Muller, Heloise; Dumas, Franck; Blanke, Bruno; Mariette, Vincent.
This study was aimed at modeling, as realistically as possible, the dynamics and thermodynamics of the Iroise Sea by using the Model for Applications at Regional Scale (MARS), a regional ocean 3D model. The horizontal resolution of the configuration in use is 2 km with 30 vertical levels. The 3D model of the Iroise Sea is embedded in a larger model providing open boundary conditions. As regards the atmospheric forcing, the originality of this study is to force the regional ocean model with the high-resolution (6 km) regional meteorological model, Weather Research and Forecasting (WRF). In addition, as the air surface temperature is highly sensitive to the sea surface temperature (SST), this regional meteorological model is improved by taking into account a...
Tipo: Text Palavras-chave: High frequency radar data; WRF; MARS; Iroise Sea.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-3518.pdf
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How fast can the European eel (Anguilla anguilla) larvae cross the Atlantic Ocean? ArchiMer
Bonhommeau, Sylvain; Blanke, Bruno; Treguier, Anne-marie; Grima, Nicolas; Rivot, Etienne; Vermard, Youen; Greiner, Eric; Le Pape, Olivier.
The migration duration of European eel (Anguilla anguilla) larvae (leptocephali) from the spawning areas in the Sargasso Sea to the European continental shelf remains highly controversial, with estimates varying from 6 months to more than 2 yr. We estimated the fastest migration period and the shortest distance travelled by eel larvae by simulating Lagrangian particles released in the Sargasso Sea and by simulating a range of larval behaviours (fixed-depth drift, vertical diurnal migration and active-depth selection to maximize current velocity). This enabled us to compute (i) a passive drift speed, and (ii) a hypothetic swimming speed needed for European eel larvae to cross the Atlantic in 6 months (i.e., the migration duration estimated from otolith...
Tipo: Text Palavras-chave: Sargasso Sea; Migration duration; Leptocephali; Lagrangian modelling; Gulf Stream; Fractals; Anguilla.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/publication-6865.pdf
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Identification of typical scenarios for the surface Lagrangian residual circulation in the Iroise Sea ArchiMer
Muller, Heloise; Blanke, Bruno; Dumas, Franck; Mariette, Vincent.
This paper describes the surface Lagrangian residual circulation (LRC) over 2.5 day intervals in the Iroise Sea, west of France, and evaluates, for operational purposes, the influence of the different physical mechanisms that govern it. The method consists of the calculation of water displacements with a diagnostic Lagrangian tool that computes the trajectories of numerical particles in a given velocity field. The LRC is inferred from trajectories integrated over five M2 tidal cycles. The analysis is applied to both gridded genuine current measurements and ocean model outputs: the sea surface currents are derived from high-frequency (HF) radar measurements and from MARS, a 3-D regional ocean model used here in idealized configurations. To substantiate the...
Tipo: Text
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00011/12220/9004.pdf
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Impacts of mesoscale activity on the water masses and circulation in the Coral Sea ArchiMer
Rousselet, L.; Doglioli, A. M.; Maes, C.; Blanke, Bruno; Petrenko, A. A..
The climatological vision of the circulation within the Coral Sea is today well established with the westward circulation of two main jets, the North Caledonian Jet (NCJ) and the North Vanuatu Jet (NVJ) as a consequence of the separation of the South Equatorial Current (SEC) on the islands of New Caledonia, Vanuatu, and Fiji. Each jet has its own dynamic and transports different water masses across the Coral Sea. The influence of mesoscale activity on mean flow and on water mass exchanges is not yet fully explored in this region of intense activity. Our study relies on the analysis of in situ, satellite, and numerical data. Indeed, we first use in situ data from the Bifurcation cruise and from an Argo float, jointly with satellite-derived velocities, to...
Tipo: Text Palavras-chave: Eddy circulation; Water masses mixing; Jets connection.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00353/46443/46188.pdf
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Improvement in airsea flux estimates derived from satellite observations ArchiMer
Bentamy, Abderrahim; Grodsky, Semyon A.; Katsaros, Kristina; Mestas-nunez, Alberto M.; Blanke, Bruno; Desbiolles, Fabien.
A new method is developed to estimate daily turbulent airsea fluxes over the global ocean on a 0.25 degrees grid. The required surface wind speed (w(10)) and specific air humidity (q(10)) at 10m height are both estimated from remotely sensed measurements. w(10) is obtained from the SeaWinds scatterometer on board the QuikSCAT satellite. A new empirical model relating brightness temperatures (T-b) from the Special Sensor Microwave Imager (SSM/I) and q(10) is developed. It is an extension of the author's previous q(10) model. In addition to T-b, the empirical model includes sea surface temperature (SST) and airsea temperature difference data. The calibration of the new empirical q(10) model utilizes q(10) from the latest version of the National Oceanography...
Tipo: Text
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00137/24825/23575.pdf
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Lagrangian ocean analysis: fundamentals and practices ArchiMer
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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Lagrangian water mass tracing from pseudo-Argo, model-derived salinity, tracer and velocity data: An application to Antarctic Intermediate Water in the South Atlantic Ocean ArchiMer
Blanke, Bruno; Speich, Sabrina; Rusciano, Emanuela.
We use the tracer and velocity fields of a climatological ocean model to investigate the ability of Argo-like data to estimate accurately water mass movements and transformations, in the style of analyses commonly applied to the output of ocean general circulation model. To this end, we introduce an algorithm for the reconstruction of a fully non-divergent three-dimensional velocity field from the simple knowledge of the model vertical density profiles and 1000-m horizontal velocity components. The validation of the technique consists in comparing the resulting pathways for Antarctic Intermediate Water in the South Atlantic Ocean to equivalent reference results based on the full model information available for velocity and tracers. We show that the...
Tipo: Text Palavras-chave: Ocean circulation; Conservation equations; Mathematical models; Density field; Subsurface drifters; Intermediate water masses.
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00238/34910/33597.pdf
Registros recuperados: 43
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