A model study of the seasonal cycle of the Arabian Sea surface temperature

Abstract

The annual variation of the SST along a zonal strip from the coast of Somalia to the southwest coast of India was simulated using available data (monthly-mean heat and momentum fluxes across the air-sea interface, surface advective field, etc.) as input to a Kraus-Turner mixed-layer model. Three cases were examined. In the first, influence of surface fluxes alone was considered. The second included the effects of surface fluxes and vertical advection. Then, effect of horizontal advection was added. The model forced with the surface heat and momentum fluxes alone simulated reasonably well the SST variability throughout the year except during the May-August (southwest monsoon) cooling phase. The model was found to be inadequate to handle the coastal areas during this phase. Over the open-sea regime the performance of the model was better; and, it improved when the influence of advection was included. The important contribution of the horizontal advection during June-August was to remove most of the heat gained at the surface during the course of a year. Though downwelling in the open-sea had little influence on the SST, it had noticeable impact on the vertical heat transport. The numerical experiments suggest that the Kraus-Turner thermodynamics alone dominate the Arabian SST variability throughout the year except during the southwest monsoon, when dynamics too play a significant role