Mesoscale variability in the Western Arabian Sea : dynamical and hydrological description compared to remote-sensing
Résumé
The Arabian Sea remained largely unexplored from the 1990's until the 2010's, and most recent studies with in situ data were focused on climatological and seasonal time scales. Thus, in-situ experiments focusing on mesoscale dynamics in this eddy rich sub-basin, are useful. The PHYSINDIEN campaign in May 2019 collected in-situ measurements of both velocity and hydrology, down to 1100m for the former and mostly to 380m for the latter. Stretching over 3000km in the Northwestern Arabian Sea, between 16 and 25⁰ N, during the spring intermonsoon, it provided an extensive dynamical and hydrological description of 8 mesoscale eddies, 5 anticyclones and 3 cyclones. Two deep cyclonic submesoscale coherent vortices remarkably occured beneath surface anticyclones. Water masses properties show that anticyclones in the Gulf of Oman are associated with lenses of Persian Gulf Waters, while anticyclones further South are shallower lenses formed with Arabian Sea High Salinity Waters. Comparison of in-situ data with the META atlas, a state-of-the-art eddy detection and tracking atlas based on altimetry, reveals that eddy radius is often underestimated. Additionally eddy track is often intermittent due to missing detections. Both hydrology and remote-sensing tracking are however consistent in indicating that anticyclones during the spring intermonsoon along the Southern Omani coast are formed further offshore at the center of the Arabian Sea. These results unveil the wide diversity of surface and subsurface eddying structures in the sparsely explored Arabian Sea, and provide hindsight on the potential bias of their remote detections.
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Est une version de hal-05501113 Article Criado Léa, Barboni Alexandre, Carton Xavier. Mesoscale processes in the northern Arabian Sea: Linking in situ observations to remote-sensing. Deep Sea Research Part II: Topical Studies in Oceanography, 2025, 224, pp.105557. ⟨10.1016/j.dsr2.2025.105557⟩. ⟨hal-05501113⟩