Bay of Bengal : 2013 northeast monsoon upper-ocean circulation

Author Posting. © The Oceanography Society, 2016. This article is posted here by permission of The Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 29, no. 2 (2016): 82–91, doi:10.5670/oceanog.2016.41.The upper 200 m of the two northern Indian Ocean embayments, the Bay of Bengal (BoB) and the Arabian Sea (AS), differ sharply in their salinity stratification, as the Asian monsoon injects massive amounts of freshwater into the BoB while removing freshwater via evaporation from the AS. The ocean circulation transfers salt from the AS to the BoB and exports freshwater from the BoB to mitigate the salinity difference and reach a quasi-steady state, albeit with strong seasonality. An energetic field of mesoscale features and an intrathermocline eddy was observed within the BoB during the R/V Revelle November and December 2013 Air-Sea Interactions Regional Initiative cruises, marking the early northeast monsoon phase. Mesoscale features, which display a surprisingly large thermohaline range within their confines, obscure the regional surface water and thermohaline stratification patterns, as observed by satellite and Argo profilers. Ocean processes blend the fresh and salty features along and across density surfaces, influencing sea surface temperature and air-sea flux. Comparing the Revelle observations to the Argo data reveals a general westward migration of mesoscale features across the BoB.Support for Bay of Bengal research is provided by the Office of Naval Research. ALG award number N00014-14-10065. AM and MF award number N00014-13-10451 and for MF a WHOI summer student fellowship. ES award number N00014-14-10236