Submesoscale Dynamics in the Gulf of Aden and the Gulf of Oman

Type Article
Date 2020-09
Language English
Author(s) Morvan Mathieu1, Carton Xavier1, Corréard Stéphanie2, Baraille Rémy2
Affiliation(s) 1 : LOPS, Univ. Brest-CNRS-IFREMER-IRD, IUEM, Rue Dumont d’Urville, 29280 Plouzané, France
2 : SHOM/DOPS/STM/DTO, Météopole, 42 Avenue Gaspard Coriolis, 31100 Toulouse Cedex 5, France
Source Fluids (2311-5521) (MDPI AG), 2020-09 , Vol. 5 , N. 3 , P. 146 (19p.)
DOI 10.3390/fluids5030146
Note This article belongs to the Special Issue Submesoscale Processes in the Ocean
Keyword(s) submesoscale instabilities, eddies and waves, upwelling fronts
Abstract

We have investigated the surface and subsurface submesoscale dynamics in the Gulf of Aden and the Gulf of Oman. Our results are based on the analyses of regional numerical simulations performed with a primitive equation model (HYCOM) at submesoscale permitting horizontal resolution. A model zoom for each gulf was embedded in a regional mesoscale-resolving simulation. In the Gulf of Aden and the Gulf of Oman, the interactions of mesoscale structures and fronts instabilities form submesoscale eddies and filaments. Rotational energy spectra show that the Gulf of Aden has a higher ratio of submesoscale to mesocale energy than the Gulf of Oman. Fast waves (internal gravity waves, tidal waves, Kelvin waves) and slow waves (Rossby waves) were characterized via energy spectra of the divergent velocity. Local upwelling systems which shed cold filaments, coastal current instabilities at the surface, and baroclinic instability at capes in subsurface were identified as generators of submesocale structures. In particular, the Ras al Hamra and Ras al Hadd capes in the Gulf of Oman, and the Cape of Berbera in the Gulf of Aden, are loci of submesoscale eddy generation. To determine the instability mechanisms involved in these generations, we diagnosed the Ertel potential vorticity and the energy conversion terms: the horizontal and vertical Reynolds stresses and the vertical buoyancy flux. Finally, the impacts of the subsurface submesoscale eddy production at capes on the diffusion and fate of the Red Sea Water (in the Gulf of Aden) and the Persian Gulf Water (in the Gulf of Oman) are highlighted

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