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| Registros recuperados: 12 | |
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| Carton, Xavier; Sokolovskiy, Mikhail; Menesguen, Claire; Aguiar, Ana; Meunier, Thomas. |
| The stability of circular vortices to normal mode perturbations is studied in a multi-layer quasi-geostrophic model. The stratification is fitted on the Gulf of Cadiz where many Mediterranean Water (MW) eddies are generated. Observations of MW eddies are used to determine the parameters of the reference experiment; sensitivity tests are conducted around this basic case. The objective of the study is two-fold: (a) determine the growth rates and nonlinear evolutions of unstable perturbations for different three-dimensional (3D) velocity structures of the vortices, (b) check if the different structure of our idealized vortices, mimicking MW cyclones and anticyclones, can induce different stability properties in a model that conserves parity symmetry, and... |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00216/32711/31363.pdf |
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| Meunier, Thomas; Sheinbaum, Julio; Pallàs Sanz, Enric; Tenreiro, Miguel; Ochoa, José; Angulo, Angel Ruiz; Carton, Xavier; Marez, Charly. |
| In this study, we harness the 25‐year satellite‐altimeter record, in concert with a vast array of in‐situ measurements, to estimate the heat content anomaly of 32 warm‐core rings in the Gulf of Mexico (GoM). The decay rate of these mesoscale eddies is studied in detail, and it is shown that they release the majority of their heat as they drift in the central GoM (away from topographic obstacles). The surface heat fluxes from the eddies is shown to be small in comparison to the total rate of heat loss from the eddies, suggesting that heat is primarily released towards the surrounding watermasses. Integrating the total heat evolution equation over the warm‐core rings yields an estimate of their effective lateral diffusivity coefficient. The long term impact... |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00606/71769/70249.pdf |
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| Colin De Verdiere, Alain; Meunier, Thomas; Ollitrault, Michel. |
| A direct method is presented to obtain the meridional overturning and heat transport in oceanic basins from observations under the sole assumptions of geostrophy and hydrostatics. The method is made possible because of the rising Argo float displacements database that can provide a reference level at 1000 dbar for the time mean circulation at 1 degrees x 1 degrees resolution. To achieve the overturning and heat transport objectives, the absolute geostrophic time mean circulation must have nondivergent barotropic transports and this requires the solutions of two Poisson equations with suitable boundary conditions, one for the geopotential at 1000 dbar and one for the barotropic stream function. Applied to the subpolar Atlantic for the period 2000-2009, an... |
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Palavras-chave: Oceanic heat transport; Meridional overturning; Subpolar Atlantic. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00589/70139/68105.pdf |
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| Meunier, Thomas; Barton, E. D.; Barreiro, B.; Torres, R.. |
| The hydrographical and dynamical properties of the upwelling filaments forming off Cap Blanc (Mauritania) are investigated using remotely sensed and in situ data collected in April/May 2009 during the strongest upwelling season. The area is situated at the southern edge of the NW African upwelling system, where the Cape Verde Frontal Zone (CVFZ) separates warmer, saltier North Atlantic Central Water (NACW) and cooler, fresher South Atlantic Central Water (SACW). Sea surface temperature images indicated the presence of an upwelling filament extending >280 km offshore, rooted over the Cap Blanc promontory and entrained around a warm-core anticyclonic eddy. After this filament started to decay, a new cold filament developed at the approximate same... |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00098/20920/18578.pdf |
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| De Marez, Charly; Meunier, Thomas; Morvan, Mathieu; L’hégaret, Pierre; Carton, Xavier. |
| We investigate the stability of a composite cyclone representative of Arabian Sea eddies using a high resolution primitive equation model. We observe that the eddy is unstable with respect to a mixed barotropic/baroclinic instability, leading to the growth of an azimuthal mode 2 perturbation. The latter deforms the eddy, which eventually evolves into a tripole after about 4 months of simulation. The presence of a critical level for the most unstable mode generates sharp fronts in the surface mixed layer where the Rossby number is large. These fronts then become unstable, and this generates submesoscale cyclones and filaments. Near these fronts, diapycnal mixing occurs, causing the potential vorticity to change sign locally, and symmetric instability to... |
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Palavras-chave: Mesoscale; Eddy; Instability; Submesoscale; Vortex. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00598/70967/69196.pdf |
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| Meunier, Thomas; Tenreiro, M.; Pallas-sanz, Enric; Ochoa, Jose; Ruiz-angulo, Angel; Portela, Esther; Cusi, Simo; Damien, Pierre; Carton, Xavier. |
| High‐resolution hydrographic measurements reveal the presence of three Intra‐Thermocline Eddies (ITEs) embedded within a Loop Current Eddy (LCE). ITEs are lenticular bodies of nearly homogeneous water which contrasts with the well stratified surrounding water. Their radii and thickness ranged between [19‐32] km and [150‐250] m. Negative relative vorticity within their cores (down to ‐0.85 times the Coriolis frequency), along with a large negative stratification anomaly, result in low Ertel Potential Vorticity (PV) and intense negative Ertel Potential Vorticity Anomalies (PVA). Vortex stretching and relative vorticity have comparable contributions to PVA, resulting in Burger numbers of order unity. The similarity of thermohaline properties within the ITE's... |
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Palavras-chave: Intrathermocline eddies; Submesoscale coherent vortices; Vortex lenses; Loop current eddy; Gulf of Mexico; Submesoscale. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00440/55122/56578.pdf |
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| De Marez, Charly; Carton, Xavier; L'Hegaret, Pierre; Meunier, Thomas; Stegner, Alexandre; Le Vu, Briac; Morvan, Mathieu. |
| Oceanic vortices are ubiquitous in the ocean. They dominate the sub-inertial energy spectrum, and their dynamics is key for the evolution of the water column properties. The merger of two like-signed coherent vortices, which ultimately results in the formation of a larger vortex, provides an efficient mechanism for the lateral mixing of water masses in the ocean. Understanding the conditions of such interaction in the ocean is thus essential. Here, we use a merger detection algorithm to draw a global picture of this process in the ocean. We show that vortex mergers are not isolated, contrary to the hypothesis made in most earlier studies. Paradoxically, the merging distance is well reproduced by isolated vortex merger numerical simulations, but it is... |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00657/76873/78117.pdf |
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| Registros recuperados: 12 | |
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