Sabiia Seb
PortuguêsEspañolEnglish
Embrapa
        Busca avançada

Botão Atualizar


Botão Atualizar

Ordenar por: RelevânciaAutorTítuloAnoImprime registros no formato resumido
Registros recuperados: 60
Primeira ... 123 ... Última
Imagem não selecionada

Imprime registro no formato completo
A near-inertial mode observed within a Gulf Stream warm-core ring ArchiMer
Joyce, Terrence M.; Toole, John M.; Klein, Patrice; Thomas, Leif N..
Layering of ocean velocity fine structure has been coherently observed across the entire extent of a Gulf Stream warm-core ring using a shipboard acoustic Doppler current profiler system in September 2009 and independently sampled as the ring transited a moored array. Lines of constant velocity phase generally followed isopycnals as they deepened within the ring center. We also observed a clear separation of the vertical structure of the flows associated with the ring (of order 0.5m/s) with the shorter (200m) and less energetic (similar to 0.2m/s) flows of the velocity fine structure, which was further observed to rotate clockwise with increasing depth, consistent with downward propagating near-inertial waves (NIWs). Observations are consistent with a...
Tipo: Text Palavras-chave: Near-inertial waves; Warm-core ring; Velocity fine structure.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00148/25929/23966.pdf
Imagem não selecionada

Imprime registro no formato completo
A numerical study of baroclinic instability at large supercriticality ArchiMer
Klein, Patrice; Pedlosky, J.
A series of numerical integrations of the two-layer quasi-geostrophic model were carried out to investigate the nonlinear dynamics of baroclinically unstable waves at supercriticalities of O(1). The results extend and are contrasted with the results of weakly nonlinear theory valid only for small supercriticality. Particular attention is paid to that sector of parameter space in which the transition from regular to aperiodic behavior is observed for weakly nonlinear waves. It is found that aperiodic, chaotic behavior extends to parameter domains of higher dissipation as a consequence of finite amplitude effects as the supercriticality increases. Sensitive dependence on parameters remains a hallmark of the system as intervals of chaotic, periodic and steady...
Tipo: Text
Ano: 1986 URL: http://archimer.ifremer.fr/doc/00254/36567/35120.pdf
Imagem não selecionada

Imprime registro no formato completo
A numerical study of turbulent processes in the marine upper layers ArchiMer
Klein, Patrice; Coantic, Michel.
A second-order turbulence closure model, similar to Mellor and Yamada's (1974) level-3 model, is implemented. This is used to investigate the role of the different turbulent processes and the resulting dynamical and thermal structures, for oceanic upper layers subjected to a variety of unsteady atmospheric forcings. From the distributions obtained for current and temperature, turbulence levels, the production, transfer and dissipation terms in the turbulent kinetic energy and temperature variance budgets, the physics of the oceanic mixed layer and thermocline can be discussed and comparisons made with the models of Mellor and Durbin (1975), Warn-Varnas and Piacsek (1979) and Kundu (1980) and some experimental data. Most often, shear production and viscous...
Tipo: Text
Ano: 1981 URL: http://archimer.ifremer.fr/doc/00254/36569/35122.pdf
Imagem não selecionada

Imprime registro no formato completo
A simulation of the effects of air-sea transfer variability on the structure of marine upper layers ArchiMer
Klein, Patrice.
A rather simple one-dimensional unsteady model similar to Mellor and Durbin (1975) is used to study the effects of the time variability of meteorological inputs on the evolution of the thermal stratification of marine upper layers. The physical implications of such a model are discussed, particularly with respect to the results obtained in a number of typical situations. The thermal structure of the marine upper layers in the Gulf of Lion during the COFRASOY II expedition was also simulated. Although the model is not able to reproduce all details of the marine environment, the mixed-layer deepening and sea surface temperature are predicted rather well from the known meteorological parameters. It appears in conclusion that the most important...
Tipo: Text
Ano: 1980 URL: http://archimer.ifremer.fr/doc/00254/36570/35124.pdf
Imagem não selecionada

Imprime registro no formato completo
An index to distinguish surface and subsurface intensified vortices from surface observations ArchiMer
Assassi, Charefeddine; Morel, Y.; Vandermeirsch, Frederic; Chaigneau, A.; Pegliasco, C.; Morrow, R.; Colas, F.; Fleury, S.; Carton, Xavier; Klein, Patrice; Cambra, R..
In this study, we first show that it is difficult to reconstruct the vertical structure of vortices using only surface observations. In particular we show that the recent SQG and ISQG methods systematically lead to surface intensified vortices and those subsurface intensified vortices are thus not correctly modelled. We then investigate the possibility to distinguish between surface and subsurface intensified eddies from surface data only, using the sea surface height and the sea surface temperature available from satellite observations. A simple index, based on the ratio of the sea surface temperature anomaly and the sea level anomaly, is proposed. While the index is expected to give perfect results for isolated vortices, we show that in a complex...
Tipo: Text
Ano: 2016 URL: https://archimer.ifremer.fr/doc/00343/45406/44921.pdf
Imagem não selecionada

Imprime registro no formato completo
Atmospheric response to sea surface temperature mesoscale structures ArchiMer
Lambaerts, J.; Lapeyre, Guillaume; Plougonven, R.; Klein, Patrice.
Recent studies have revealed that strong sea surface temperature (SST) fronts, on the scale of a Western Boundary Current, significantly affect not just the Marine Boundary Layer but the entire troposphere. This has aroused renewed interest in air-sea interactions. The present study investigates the atmospheric response to fixed SST anomalies associated with mesoscale oceanic eddies and submesoscale filaments, using idealized simulations. Our main result is that in weak wind conditions, the vertical velocity in the planetary boundary layer (PBL) is linearly proportional to the SST Laplacian. This is established by a quantitative analysis in the spatial space as well as in the spectral space. Comparing the responses to two different SST fields shows that...
Tipo: Text Palavras-chave: Air-sea interactions; Boundary layer; Sea surface temperature.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00169/28047/26247.pdf
Imagem não selecionada

Imprime registro no formato completo
Available potential energy diagnosis in a direct numerical simulation of rotating stratified turbulence ArchiMer
Roullet, Guillaume; Klein, Patrice.
Review of three studies devoted to the available potential energy (APE) leads to the proposal of a diagnosis for APE, well-suited for rotating stratified flows within the primitive equations (PE) framework in which anharmonic effects (due to large vertical displacements of isopycnals) are permitted. The chosen diagnosis is based on the APE definition of Holliday & McIntyre (J. Fluid Mech., vol. 107, 1981, pp. 221-225) and uses the background stratification of Winters et al. (J. Fluid Mech., vol. 289, 1995, pp. 115-128). Subsequent evaluation of the APE in a PE direct simulation (1/100 degrees, 200 levels) of oceanic mesoscale turbulence indicates that anharmonic effects are significant. These effects are due to large vertical displacements of the...
Tipo: Text
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/publication-6391.pdf
Imagem não selecionada

Imprime registro no formato completo
Can oceanic submesoscale processes be observed with satellite altimetry? ArchiMer
Chavanne, Cedric; Klein, Patrice.
High-resolution (2 km and hourly) observations of surface currents from High-Frequency Radars are analyzed in terms of sea level anomalies (SLA) and compared with data from two satellite altimeter ground tracks. Purpose is to investigate whether ocean submesoscale processes can be observed with satellite altimetry. Our results highlight two major problems that must be overcome before being able to resolve submesoscale processes with altimetry: (i) signal contamination from high-frequency motions and in particular from incoherent internal tides (near-inertial oscillations have no effect on SLA), and (ii) measurement noise which prevents the computation of accurate cross-track currents on scales O (10 km). The latter may be overcome by future satellite...
Tipo: Text
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00019/13037/10153.pdf
Imagem não selecionada

Imprime registro no formato completo
Characterization of tracer cascade in physical space ArchiMer
Hua, Bach-lien; Klein, Patrice; Lapeyre, Guillaume.
Geophysical turbulent fluids are characterized by the presence of organized energetic structures which control tracer transport and stirring, while enabling a tracer cascade down to the smallest scales. In order to understand the physical mechanisms involved in this turbulent tracer cascade, we focus on the dynamics underlying the formation of tracer gradients which are necessarily associated to this cascade. We show that the dynamics of tracer gradients in physical space is mainly governed by their orientation with respect to the compressional eigenvector of the strain tensor. This relative angle results from the competition between strain and the "effective rotation" (due to both vorticity and rotation of strain axes). The implication is that tracer...
Tipo: Text
Ano: 2001 URL: http://archimer.ifremer.fr/doc/00067/17786/15309.pdf
Imagem não selecionada

Imprime registro no formato completo
Cyclone-Anticyclone Asymmetry in Geophysical Turbulence ArchiMer
Roullet, Guillaume; Klein, Patrice.
We address the problem of cyclone-anticyclone asymmetry in geophysical turbulence using a direct numerical simulation with high Reynolds number Re similar to 15 000 that includes an active upper boundary and interior dynamics. The regime, characterized by a finite Rossby number (Ro similar to 0.6) strongly departs from the classical quasigeostrophic regime. The numerical resolution is pushed to the limit of today's supercomputer capabilities ensuring more than two decades free of viscous effects. The results show a strong cyclonic dominance in the upper layers that is stronger for filaments than for vortices. This is in contrast with similar studies that have no active upper boundary which reported either anticyclone dominance or a symmetry between...
Tipo: Text
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00005/11587/8240.pdf
Imagem não selecionada

Imprime registro no formato completo
Deep ocean inertia-gravity waves simulated in a high-resolution global coupled atmosphere-ocean GCM - art. no. L04610 ArchiMer
Komori, N; Ohfuchi, W; Taguchi, B; Sasaki, H; Klein, Patrice.
In order to investigate the deep ocean inertia-gravity waves, a high-resolution global coupled atmosphere-ocean simulation is carried out with a coupling interval of 20 minutes. Large (similar to 10(-3) m s(-1)) root-mean-square variability of vertical velocity is found in middepths (2000-4000 m), which is not reported in previous studies using realistic ocean simulations. Horizontal distribution of the large variability roughly corresponds to the wintertime atmospheric storm tracks and is stretched equatorward due to beta-dispersion in open ocean with some "shadow regions'' behind the obstacles. Frequency spectrum of vertical velocity has strong peaks at around f and 2f (f is the local inertial period) in midlatitudes, and has additional peak at around...
Tipo: Text Palavras-chave: Coupled atmosphere ocean model; Deep ocean; Inertia gravity wave.
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/publication-3825.pdf
Imagem não selecionada

Imprime registro no formato completo
Destabilization of mixed Rossby gravity waves and the formation of equatorial zonal jets ArchiMer
Hua, Bach-lien; D'Orgeville, Marc; Fruman, Mark; Menesguen, Claire; Schopp, Richard; Klein, Patrice; Sasaki, H.
stability of mixed Rossby gravity (MRG) waves has been investigated numerically using three-dimensionally consistent high-resolution Simulations of the continuously stratified primitive equations. For short enough zonal wavelength, the westward phase propagating MRG wave is strongly destabilized by barotropic shear instability leading , to the formation of zonal jets. The large-scale instability of the zonally short wave,generates zonal jets because it consists primarily of sheared meridional motions, as shown recently for the short barotropic Rossby wave problem. Simulations were done in a variety of domain geometries: a periodic re-entrant channel, a basin with a short MRG wave forced in its western part and a very long channel initialized with a...
Tipo: Text
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/publication-5913.pdf
Imagem não selecionada

Imprime registro no formato completo
Diagnosing ocean‐wave‐turbulence interactions from space ArchiMer
Torres, H.s.; Klein, Patrice; Siegelman, L.; Qiu, B.; Chen, S.; Ubelman, C.; Wang, J.; Menemenlis, D.; Fu, L.‐l..
Numerical studies indicate that interactions between ocean internal gravity waves (especially those <100 km) and geostrophic (or balanced) motions associated with mesoscale eddy turbulence (involving eddies of 100–300 km) impact the ocean's kinetic energy budget and therefore its circulation. Results from these studies have never been confirmed by observations in regional or basin‐scale domains. Here we show that internal gravity waves have a spectral signature on sea‐surface height (SSH) during summer that significantly differs from that of balanced motions. These spectral differences lead us to propose a new dynamical framework that quantifies the interactions between internal gravity waves and balanced motions in physical space from SSH snapshots,...
Tipo: Text
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00509/62035/66167.pdf
Imagem não selecionada

Imprime registro no formato completo
Diagnosing Surface Mixed Layer Dynamics from High-Resolution Satellite Observations: Numerical Insights ArchiMer
Ponte, Aurelien; Klein, Patrice; Capet, Xavier; Le Traon, Pierre-yves; Chapron, Bertrand; Lherminier, Pascale.
High-resolution numerical experiments of ocean mesoscale eddy turbulence show that the wind-driven mixed layer (ML) dynamics affects mesoscale motions in the surface layers at scales lower than O(60 km). At these scales, surface horizontal currents are still coherent to, but weaker than, those derived from sea surface height using geostrophy. Vertical motions, on the other hand, are stronger than those diagnosed using the adiabatic quasigeotrophic (QG) framework. An analytical model, based on a scaling analysis and on simple dynamical arguments, provides a physical understanding and leads to a parameterization of these features in terms of vertical mixing. These results are valid when the wind-driven velocity scale is much smaller than that associated with...
Tipo: Text Palavras-chave: Mesoscale processes; Ocean dynamics; Turbulence.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00170/28076/26291.pdf
Imagem não selecionada

Imprime registro no formato completo
Diagnosis of vertical velocities in the upper ocean from high resolution sea surface height ArchiMer
Klein, Patrice; Isern-fontanet, Jordi; Lapeyre, Guillaume; Roullet, G.; Danioux, Eric; Chapron, Bertrand; Le Gentil, Sylvie; Sasaki, H..
A surface Quasi-Geostrophy based (eSQG) method to diagnose the vertical velocity field from Sea Surface Height (SSH) is assessed using high resolution simulations. These simulations concern a turbulent eddy field with large Rossby numbers and energetic wind-driven motions. Results indicate that low-frequency vertical velocities (and also horizontal motions) can be reconstructed within a range of scales between 20 km and 400 km from the surface down to 500 m. The only information needed is a single high-resolution SSH snapshot and information on the large-scale vertical stratification. Inertial motions are naturally filtered because they do not contaminate SSH as we demonstrate. These results are encouraging and further strengthen previous studies using the...
Tipo: Text
Ano: 2009 URL: http://archimer.ifremer.fr/doc/00000/11094/7418.pdf
Imagem não selecionada

Imprime registro no formato completo
Dissipation of the energy imparted by mid-latitude storms in the Southern Ocean ArchiMer
Jouanno, Julien; Capet, Xavier; Madec, Gurvan; Roullet, Guillaume; Klein, Patrice.
The aim of this study is to clarify the role of the Southern Ocean storms on interior mixing and meridional overturning circulation. A periodic and idealized numerical model has been designed to represent the key physical processes of a zonal portion of the Southern Ocean located between 70 and 40° S. It incorporates physical ingredients deemed essential for Southern Ocean functioning: rough topography, seasonally varying air–sea fluxes, and high-latitude storms with analytical form. The forcing strategy ensures that the time mean wind stress is the same between the different simulations, so the effect of the storms on the mean wind stress and resulting impacts on the Southern Ocean dynamics are not considered in this study. Level and distribution of...
Tipo: Text
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00343/45404/44919.pdf
Imagem não selecionada

Imprime registro no formato completo
Do altimeter wavenumber spectra agree with the interior or surface quasigeostrophic theory? ArchiMer
Le Traon, Pierre-yves; Klein, Patrice; Hua, Bach-lien; Dibarboure, G.
In high-eddy-energy regions, it is generally assumed that sea level wavenumber spectra compare well with quasigeostrophic (QG) turbulence models and that spectral slopes are close to the expected k(-5) law. This issue is revisited here. Sea level wavenumber spectra in the Gulf Stream, Kuroshio, and Agulhas regions are estimated using the most recent altimeter datasets [the Ocean Topography Experiment (TOPEX)/ Poseidon, Jason-1, the Environmental Satellite (Envisat), and the Geosat Follow-On]. The authors show that spectral slopes in the mesoscale band are significantly different from a k(-5) law, in disagreement with the QG turbulence theory. However, they very closely follow a k(-11/3) slope, which indicates that the surface quasigeostrophic theory (SQG)...
Tipo: Text
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/publication-4118.pdf
Imagem não selecionada

Imprime registro no formato completo
Dynamic Interpolation of Sea Surface Height and Potential Applications for Future High-Resolution Altimetry Mapping ArchiMer
Ubelmann, Clement; Klein, Patrice; Fu, Lee-lueng.
Many issues may challenge standard interpolation techniques to produce high-resolution gridded maps of sea surface height in the context of future missions like Surface Water and Ocean Topography (SWOT). The present study proposes a new method to address these challenges. Based on the conservation of potential vorticity, the method provides a simple dynamic approach to interpolation through temporal gaps between high spatial resolution observations. For gaps shorter than 20 days, the dynamic interpolation is extremely efficient and allows for the reconstruction of the time evolution of small mesoscale eddies (below 100 km) that would be smoothed out by conventional methods based on optimal mapping. Such a simple approach offers some perspectives for...
Tipo: Text Palavras-chave: : Conservation equations; Eddies; Mesoscale processes; Mesoscale forecasting; Interpolation schemes; Quasigeostrophic models.
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00252/36313/34865.pdf
Imagem não selecionada

Imprime registro no formato completo
Effects of an asymmetric friction on the nonlinear equilibration of a baroclinic system ArchiMer
Riviere, Pascal; Klein, Patrice.
Following some recent linear and nonlinear studies the authors examine, using numerical simulations of a classical two-layer model, the effect of an asymmetric friction on the nonlinear equilibrium of moderately unstable baroclinic systems, The results show that the presence of an asymmetric friction leads to a significant wave scale selection: ''long'' waves (in terms of their zonal wavelengths) emerge with a traditional asymmetric friction (with the upper layer less viscous than the lower layer), while only ''short'' waves dominate with a nontraditional asymmetric friction (with the lower layer less viscous than the upper layer). The role of the nonlinear interactions and. more precisely, the effects of an asymmetric friction on the wave-mean flow and...
Tipo: Text
Ano: 1997 URL: http://archimer.ifremer.fr/doc/00336/44705/44915.pdf
Imagem não selecionada

Imprime registro no formato completo
Estimation of the Agulhas ring impacts on meridional heat fluxes and transport using ARGO floats and satellite data ArchiMer
Azevedo Correia, Joao Marcos; De Boyer Montegut, Clement; Cabanes, Cecile; Klein, Patrice.
A method that combines vertical profiles from the ARGO floats program and satellite Sea Surface Height (SSH) data is used to reconstruct the vertical structure of the Agulhas rings. All eddies shed by the Agulhas retroflection in the period between January 2005 and December 2008 were successfully reconstructed. The velocity structures obtained are tilted and phase shifted in relation to the temperature anomalies, resulting in an annual mean eddy meridional heat flux across the ring paths of 0.062 +/- 0.012 PW (northward). A first order estimate indicates 0.07 PW entering the Atlantic from the Indian Ocean through Agulhas rings. The volume transport by Agulhas rings is believed to play a central role in the overturning circulation, being the main process...
Tipo: Text
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00051/16221/13746.pdf
Registros recuperados: 60
Primeira ... 123 ... Última
 

Empresa Brasileira de Pesquisa Agropecuária - Embrapa
Todos os direitos reservados, conforme Lei n° 9.610
Política de Privacidade
Área restrita

Embrapa
Parque Estação Biológica - PqEB s/n°
Brasília, DF - Brasil - CEP 70770-901
Fone: (61) 3448-4433 - Fax: (61) 3448-4890 / 3448-4891 SAC: https://www.embrapa.br/fale-conosco

Valid HTML 4.01 Transitional