Estimation of wind stress induced offshore upwelling

Offshore upwellings over the Arabian Sea and the Bay of Bengal are estimated using the MONEX-79 ship wind data, using a computational approach based on Stokeʹs theorem. The estimated upwellings over the Arabian Sea during May are found to correlate with the daily vertical movements of the 28.5°C isotherm, while those over the Bay of Bengal during July are found to correlate better with the isotherm movements with a lag of one day. This could be because the mean depth of 28.5°C isotherm during the study period in May in the Arabian Sea was around 36 m and that in July was around 49 m in the Bay of Bengal leading to some time delay for the surface wind stress effects to reach at greater depths.