Mesoscale dynamics in the Arabian Sea and a focus on the Great Whirl life cycle: A numerical investigation using ROMS

Type Article
Date 2014-09
Language English
Author(s) Vic Clement1, Roullet Guillaume1, Carton Xavier1, Capet X.2
Affiliation(s) 1 : CNRS Ifremer IRD UBO, UMR 6523, Lab Phys Oceans, Brest, France.
2 : CNRS UPMC IRD MNHN, UMR 7159, IPSL LOCEAN, Paris, France.
Source Journal Of Geophysical Research-oceans (0148-0027) (Amer Geophysical Union), 2014-09 , Vol. 119 , N. 9 , P. 6422-6443
DOI 10.1002/2014JC009857
WOS© Times Cited 39
Keyword(s) Arabian Sea, Indian Ocean, Great Whirl, mesoscale dynamics, ROMS, Rossby waves
Abstract The Great Whirl (GW) is a persistent anticyclonic mesoscale eddy that is observed seasonally in the Arabian Sea during a period embedding the 3 months of the southwest monsoon (June–July–August) at a quasi-steady location. Its dynamics remain unclear despite it being one of the largest coherent vortices in the world ocean. Realistic regional numerical experiments using ROMS are performed to investigate the life cycle of the GW, which is not well resolved by sparse available in situ measurements in the region. Using a set of sensitivity experiments and an accurate temporal characterization of the eddy properties (including position, radius, depth, and vorticity) we (i) confirm the role of basin-scale downwelling Rossby waves in the GW generation, (ii) clarify the role of the monsoonal strong anticyclonic wind in its maintenance and barotropization, and (iii) suggest a connection between basin-scale Rossby wave dynamics and GW collapse.
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