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Influence de la bathymétrie sur les instabilités de courants côtiers et la formation de tourbillons : de l'observation en Méditerranée orientale à la modélisation idéalisée

Abstract : The Atlantic Water transport in the eastern Mediterranean is strongly impacted by the dynamics of mesoscale eddies. The latter are mainly produced through baroclinic instability of coastal currents. These eddies, as well as the meanders characterizing the instabilities, play an important part in the transport of water masses, heat, and nutriments between the coast and the open sea. Those transfers have to be well represented in numerical simulations used in decision-making processes facing socio-economic issues. Nevertheless, the impact of the bathymetry on the general ocean surface circulation in the Mediterranean is still poorly understood. This PhD work aims at understanding and quantifying the impact of the undersea topography on current instabilities and on the dynamics of eddies formed alongshore. Observations of those features in the eastern Mediterranean, using surface drifters and numerical simulations, confirm that they are ubiquitous and that they influence strongly the surface circulation. This study highlights also the difficulties of numerical models in reproducing those eddies. The baroclinic instability above a topographic slope is then studied by means of an idealized coastal current produced both in laboratory experiments on a turntable and in high resolution numerical simulations. The combined use of these two methodologies emphasizes the stabilizing effect of the bathymetry inducing a decrease of the unstable growth rates and the formation of smaller scale structures as the topographic slope increases. The dynamics of these features above a slope is then driven by non-linear processes yielding the formation of submesoscale structures.
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https://pastel.archives-ouvertes.fr/pastel-00678412
Contributor : Romain Pennel <>
Submitted on : Monday, March 12, 2012 - 5:19:06 PM
Last modification on : Wednesday, July 3, 2019 - 10:48:04 AM
Long-term archiving on: : Thursday, June 14, 2012 - 3:09:26 PM

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  • HAL Id : pastel-00678412, version 1

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Romain Pennel. Influence de la bathymétrie sur les instabilités de courants côtiers et la formation de tourbillons : de l'observation en Méditerranée orientale à la modélisation idéalisée. Physique Atmosphérique et Océanique [physics.ao-ph]. Ecole Polytechnique X, 2011. Français. ⟨pastel-00678412⟩

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