Data/hora: 11/06/2024 14:41:13

Provedor de dados: | 5
País: | France

Título:

Dynamique de bord ouest en mer d'Arabie

Western Boundary Dynamics in the Arabian Sea

Autores: | Vic, Clement.
Data: | 2015-11-12
Ano: | 2015
Palavras-chave: | Mer d'Arabie; Outfow; Golfe d'Oman; Golfe Persique; Ondes de Rossby; Upwelling; Dynamique de mésoéchelle et sous-mésoéchelle; Modélisation réaliste; Interactions tourbillon-topographie; Ocean modelling; Mesoscale and submesoscale dynamics; Arabian Sea; Great Whirl; Outflow; Gulf of Oman; Persian Gulf; Rossby waves; Eddy-topography interactions.
Resumo: | This PhD aims to investigate some western boundary processes in the Arabian Sea : (i) the life cycle of the socalled Great Whirl, a persistent mesoscale eddy; (ii) the dynamics of the Persian Gulf outflow, a marginal sea dense outflow; and (iii) the seasonal Oman upwelling, a coastal upwelling forced by summermonsoonal winds. The cornerstone of all these phenomena is their locationat a western boundary, which makes then being influenced by both localforcing (e.g., monsoonal winds) and remote forcing (Rossby waves and wesward drifting eddies). Specifically, the later are expected to impact the western boundary dynamics since the low latitude of the Arabian Sea implies a fast westward propagation of long Rossby waves and eddies. Moreover, waves are continously excited by the reversing monsoonal winds. Based on a primitive equation model, we designed numerical experiments of different complexity that allowed to either realistically simulate the dynamics in the Arabian Sea or to isolate some processes.Major findings can be summarized as follows : (i) The Great Whirl life cycle is found to be significantly paced by annual Rossby waves, although the strong monsoonal wind stress curl is of major importance to sustain the structure. (ii) The Persian Gulf Water (PGW) spreading in the Gulf of Oman and the northern Arabian Sea can be explained by the stirring done by eddies entering the Gulf. These remotely formed surface intensifed mesoscale eddies propagate into the Gulf and interact with the topography. Frictional interactions produce intense vorticity strips at the boundary that detach and roll up in the interior, forming submesoscale coherent vortices (SCV). These SCV trap PGW initially located on the slope and redistribute it in the interior. This mechanism of transport ultimately produces mixing that explains the large-scale gradient of salinity in the gulf. (iii) We find that the dynamics of the seasonal upwelling of Oman contrasts with the more deeply studied Eastern Boundary Upwelling Systems (EBUS). In particular, Rossby waves, propagating offshore in EBUS vs. onshore in this western boudary upwelling, are found to modulate the wind driven upwelling and its sea surface temperature response.Overall, these results appear to be rather specific to the Arabian Sea. The short zonal extent and the low-latitude of the Arabian Sea, as well as the seasonally reversing wind forcing are the distinguishing features of this region. Fast waves and drifting eddies and their interactions with the western boundary significantly shape the turbulent regimes of the western Arabian Sea.
Tipo: | Text
Idioma: | Francês

Identificador:

https://archimer.ifremer.fr/doc/00498/60934/64328.pdf

https://archimer.ifremer.fr/doc/00498/60934/

Editor: | Université de Bretagne occidentale
Formato: | application/pdf

Fonte:

info:eu-repo/semantics/openAccess

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