Response of southwest monsoon winds on shelf circulation off Kerala Coast, India

Three-dimensional Princeton Ocean Model is used to investigate the dynamics of the shelf flow response to the spatial and temporal variability of the wind stress forcing along the Kerala Coast. The model is configured for the west coast of India with higher horizontal resolution near the coast. In the vertical, a terrain following sigma coordinate is used, having finer resolution near the surface and bottom. In the present study, an attempt is made to understand the variability of the surface circulation and associated SST during July–August for 2000 and 2002 as a response of daily wind stress forcing derived from the QSCAT winds. The southerly current during July–August supports upwelling processes along the Kerala Coast. From the available buoy observations and simulations, it is noted that the coastal current reverses its direction to either off-shore or northward if the wind magnitude reduces suddenly below 3 m s−1 towards the coast. In this event, the coastal upwelling is inhibited by the reversal of currents and it results an increase in the local SST. The reversal of currents is explained in terms of local vorticity generated as a result of reduction of wind magnitude near the coast.