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| Registros recuperados: 14 | |
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| Lavergne, C.; Vic, Clement; Madec, G; Roquet, F.; Waterhouse, A. F.; Whalen, C. B.; Cuypers, Y.; Bouruet‐aubertot, P.; Ferron, Bruno; Hibiya, T.. |
| Vertical mixing is often regarded as the Achilles' heel of ocean models. In particular, few models include a comprehensive and energy‐constrained parameterization of mixing by internal ocean tides. Here, we present an energy‐conserving mixing scheme which accounts for the local breaking of high‐mode internal tides and the distant dissipation of low‐mode internal tides. The scheme relies on four static two‐dimensional maps of internal tide dissipation, constructed using mode‐by‐mode Lagrangian tracking of energy beams from sources to sinks. Each map is associated with a distinct dissipative process and a corresponding vertical structure. Applied to an observational climatology of stratification, the scheme produces a global three‐dimensional map of... |
| Tipo: Text |
Palavras-chave: Ocean mixing; Internal tides; Parameterization; Energy dissipation. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00624/73573/72943.pdf |
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| Treguier, Anne-marie; Boebel, O; Barnier, B; Madec, G. |
| A 1/6degrees resolution primitive equation model of the Atlantic circulation is analyzed in the Agulhas region. The model has a realistic level of eddy kinetic energy, and produces anticyclonic Agulhas rings as well as cyclonic structures. In the model as well as in the data, ring trajectories undergo a transition between a turbulent character in the Cape Basin and a steady propagation in the rest of the South Atlantic. The topography of the Walvis Ridge does not seem to play a part in generating this contrast in the model. The model shows that cyclones are primarily generated from the negative shear vorticity side of the Agulhas Current as it leaves the coast, and they are most of the time paired with anticyclones in dipolar or tripolar structures.... |
| Tipo: Text |
Palavras-chave: South Africa; South Atlantic Ocean; Numerical model; Ocean currents; Oceanic eddies; Eddy flux. |
| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/2003/publication-453.pdf |
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| 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... |
| Tipo: Text |
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| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/00000/10613/9403.pdf |
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| Masson, S; Luo, Jj; Madec, G; Vialard, Jerome; Durand, F; Gualdi, S; Guilyardi, E; Behera, S; Delecluse, P; Navarra, A; Yamagata, T. |
| In the present study, we use a coupled model to evaluate the effect of shallow salinity stratification on the sea surface temperature (SST) and on the monsoon onset in the southeastern Arabian Sea (SEAS). A 100-year control experiment shows that the coupled model reproduces the main climatic features in this region in terms of SST, precipitation and barrier layer (BL). A 100-year sensitivity experiment (where BL effects have been suppressed in the SEAS) shows that BL enhances the spring SST warming by 0.5 degrees C, and leads to a statistically significant increase of precipitation in May (3 mm/day) linked to an early (10 to 15 days) monsoon onset. This suggests that the BL extent may be a useful predictor of the summer monsoon onset in the area with a... |
| Tipo: Text |
Palavras-chave: Summer monsoon season; Surface temperature; Indian ocean; Mixed layer; Northeast monsoon; Southwest monsoon; Onset vortex; Coupled GCM; Mechanisms; Evolution. |
| Ano: 2005 |
URL: https://archimer.ifremer.fr/doc/00203/31422/29819.pdf |
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| Barnier, B; Madec, G; Penduff, T; Molines, J; Treguier, Anne-marie; Le Sommer, J; Beckmann, A; Biastoch, A; Boning, C; Dengg, J; Derval, C; Durand, E; Gulev, S; Remy, E; Talandier, Claude; Theetten, Sebastien; Maltrud, M; Mcclean, J; De Cuevas, B. |
| Series of sensitivity tests were performed with a z-coordinate, global eddy-permitting (1/4 degrees) ocean/sea-ice model (the ORCA-R025 model configuration developed for the DRAKKAR project) to carefully evaluate the impact of recent state-of-the-art numerical schemes on model solutions. The combination of an energy-enstrophy conserving (EEN) scheme for momentum advection with a partial step (PS) representation of the bottom topography yields significant improvements in the mean circulation. Well known biases in the representation of western boundary currents, such as in the Atlantic the detachment of the Gulf Stream, the path of the North Atlantic Current, the location of the Confluence, and the strength of the Zapiola Eddy in the south Atlantic, are... |
| Tipo: Text |
Palavras-chave: Eddy/topography interactions; Partial step topography; Momentum advection scheme; Eddy permitting ocean model; Global ocean. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-3514.pdf |
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| Raynaud, Stephane; Speich, Sabrina; Guilyardi, E; Madec, G. |
| A global coupled General Circulation Model is used to investigate effects of the lateral ocean mixing on the amplitude and spectral characteristics of the ENSO-like variability. Three 40-year coupled simulations are analysed. They only differ by the lateral ocean physics parametrized: a horizontal diffusion scheme; an isopycnal scheme; isopycnal scheme with an Eddy Induced Velocity (EIV) term.The Multichannel Singular Spectrum Analysis is used to extract linear modes of variability from each simulation and from observations. The strength of the variability, close to that observed in the horizontal and only-isopycnal simulations, is stronger in the two isopycnal configurations, and more especially when the EIV is added. The dominant periods of the... |
| Tipo: Text |
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| Ano: 2000 |
URL: http://archimer.ifremer.fr/doc/00000/10451/9563.pdf |
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| Penduff, T; Le Sommer, J; Barnier, B; Treguier, Anne-marie; Molines, J; Madec, G. |
| The combined use of partial steps and of an energy-enstrophy conserving momentum advection scheme was shown by Barnier et al. (2006) to yield substantial improvements in the surface solution of the DRAKKAR 4 global sea-ice/ocean model. The present study extends this investigation below the surface with a special focus on the Atlantic and reveals many improvements there as well: e.g. more realistic path, structure and transports of major currents (Gulf Stream, North Atlantic Current, Confluence region, Zapiola anticyclone), behavior of shedded rings, narrower subsurface boundary currents, stronger mean and eddy flows (MKE and EKE) at depth, beneficial enhancement of cyclonic (anticyclonic) flows around topographic depressions (mountains). Interestingly,... |
| Tipo: Text |
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| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-3712.pdf |
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| Treguier, Anne-marie; Molines, J. M.; Madec, G. |
| This report contributes to the preliminary validation of the ORCA025 configuration of the DRAKKAR project (www.ifremer.fr/lpo/drakkar). Only experiments forced by a repeated seasonal cycle forcing are considered here. Most of the plots are for the global ocean but some emphasize the Southern Ocean. The model (ORCA025) is the 1/4 global configuarion of the DRAKKAR project. It uses the NEMO system: OPA9 coupled with the LIM sea ice model, www.lodyc.jussieu.fr/NEMO. The configuration is described in Barnier et al. (2006). The main experiment considered here, ORCA025-G42, is short: it lasts 10 years. |
| Tipo: Text |
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| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/rapport-6501.pdf |
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| Danabasoglu, Gokhan; Yeager, Steve G.; Bailey, David; Behrens, Erik; Bentsen, Mats; Bi, Daohua; Biastoch, Arne; Boening, Claus; Bozec, Alexandra; Canuto, Vittorio M.; Cassou, Christophe; Chassignet, Eric; Coward, Andrew C.; Danilov, Sergey; Diansky, Nikolay; Drange, Helge; Farneti, Riccardo; Fernandez, E; Fogli, Pier Giuseppe; Forget, Gael; Fujii, Yosuke; Griffies, Stephen M.; Gusev, Anatoly; Heimbach, Patrick; Howard, Armando; Jung, Thomas; Kelley, Maxwell; Large, William G.; Leboissetier, Anthony; Lu, Jianhua; Madec, G; Marsland, Simon J.; Masinam, Simona; Navarram, Antonio; Nurser, A. J. George; Pirani, Anna; Salas Y Melia, David; Samuels, Bonita L.; Scheinert, Markus; Sidorenko, Dmitry; Treguier, Anne-marie; Tsujino, Hiroyuki; Uotila, Petteri; Valcke, Sophie; Voldoire, Aurore; Wangi, Qiang. |
| Simulation characteristics from eighteen global ocean–sea-ice coupled models are presented with a focus on the mean Atlantic meridional overturning circulation (AMOC) and other related fields in the North Atlantic. These experiments use inter-annually varying atmospheric forcing data sets for the 60-year period from 1948 to 2007 and are performed as contributions to the second phase of the Coordinated Ocean-ice Reference Experiments (CORE-II). The protocol for conducting such CORE-II experiments is summarized. Despite using the same atmospheric forcing, the solutions show significant differences. As most models also differ from available observations, biases in the Labrador Sea region in upper-ocean potential temperature and salinity distributions, mixed... |
| Tipo: Text |
Palavras-chave: Global ocean-sea-ice modelling; Ocean model comparisons; Atmospheric forcing; Experimental design; Atlantic meridional overturning circulation; North Atlantic simulations. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00164/27525/28368.pdf |
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| Lehucher, Pm; Beautier, L; Chartier, M; Martel, F; Mortier, L; Brehmer, P; Millot, C; Alberola, C; Benzhora, M; Taupierletage, I; Dhieres, Gc; Didelle, H; Gleizon, P; Obaton, D; Crepon, M; Herbaut, C; Madec, G; Speich, S; Nihoul, J; Beckers, Jm; Brasseur, P; Deleersnijder, E; Djenidi, S; Font, J; Castellon, A; Garcialadona, E; Lopezgarcia, Mj; Manriquez, M; Maso, M; Salat, J; Tintore, J; Alonso, S; Gomis, D; Viudez, A; Astraldi, M; Bacciola, D; Borghini, M; Dellamico, F; Galli, C; Lazzoni, E; Gasparini, Gp; Sparnocchia, S; Harzallah, A. |
| The present paper describes the major results obtained from 1989 to 1992 by the EUROMODEL group in studying the circulation in the Western Mediterranean Sea. Particular emphasis has been given to the physical processes responsible for seasonal and mesoscale variabilities. Observations (in situ and satellite), together with theoretical, physical and numerical models, have been widely used in the course of these studies. Attention has been focused on the dynamics of the northern basin (deep water formation, dynamics of the Northern Mediterranean Current, circulation and shelf/slope interaction in the Balearic Sea) and of the southern basin (Alboran Sea circulation, instabilities of the Algerian Current). The straits dynamics have been studied with particular... |
| Tipo: Text |
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| Ano: 1995 |
URL: http://archimer.ifremer.fr/doc/00097/20776/18519.pdf |
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| Rodgers, Kb; Aumont, O; Madec, G; Menkes, C; Blanke, Bruno; Monfray, P; Orr, Jc; Schrag, Dp. |
| An ocean model is used to test the idea that sea surface Delta(14)C behaves as a thermocline proxy in the eastern equatorial Pacific. The ORCA2 model, which includes Delta(14)C as a passive tracer, has been forced with reanalysis fluxes over 1948-1999, and the output is compared with a previously reported Galapagos Delta(14)C record. The model reproduces the abrupt increase in the seasonally minimum Delta(14)C in 1976/77 found in the data. This increase is associated with neither a shift of thermocline depth over the NINO3 region, nor a change in the relative proportion of Northern/Southern source waters. Rather, it is due to a decrease in the Sub-Antarctic Mode Water (SAMW) component of the upwelling water, thereby representing a decrease in entrainment... |
| Tipo: Text |
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| Ano: 2004 |
URL: https://archimer.ifremer.fr/doc/00000/10834/9261.pdf |
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| Treguier, Anne-marie; England, M; Rintoul, S; Madec, G; Le Sommer, J; Molines, J. |
| An eddying global model is used to study the characteristics of the Antarctic Circumpolar Current (ACC) in a streamline-following framework. Previous model-based estimates of the meridional circulation were calculated using zonal averages: this method leads to a counter-intuitive pole-ward circulation of the less dense waters, and underestimates the eddy effects. We show that on the contrary, the upper ocean circulation across streamlines agrees with the theoretical view: an equatorward mean flow partially cancelled by a poleward eddy mass flux. Two model simulations, in which the buoyancy forcing above the ACC changes from positive to negative, suggest that the relationship between the residual meridional circulation and the surface buoyancy flux is not... |
| Tipo: Text |
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| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-3713.pdf |
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| Speich, Sabrina; Blanke, Bruno; Madec, G. |
| A global general circulation model analyzed with a Lagrangian methodology is used to describe and quantify the paths, transports, and characteristics of the "warm" waters forming the upper branch of the conveyor belt in the North Atlantic Ocean. The total transport for this branch turns out to be 17.8 Sv in the North Atlantic at 20 degrees N: 11.8 Sv are composed of waters coming from the two classical origins, the Drake Passage and the Indonesian Throughflow which contribute with 6.5 and 5.3 Sv respectively. The remaining 6 Sv find their origins partly in the passage between Antarctica and the Australian Continent (with 3.1 Sv) and partly in the Indo-Atlantic sector itself (i.e., with 2.9 Sv). The geographical structure of the different routes emphasizes... |
| Tipo: Text |
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| Ano: 2001 |
URL: http://archimer.ifremer.fr/doc/00000/10597/7735.pdf |
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| Registros recuperados: 14 | |
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