The coastal ocean's response to a tropical cyclone in Bay of Bengal

A three-dimensional numerical model is used to study the response of a coastal ocean excited by a tropical cyclone in the Bay of Bengal. It is found that weak forcing representative of the early pre-monsoonal phase is sufficient to lead to a frontal formation and variability on a 6-day time-scale; this is accompanied by localized reduction in the sea-surface temperature of the order of those observed during the period. According to the observations in the Bay of Bengal, the occurrences of atmospheric systems like depressions or cyclonic storms are common in the month of May. In the present study, the model is driven starting from rest with mean monthly wind-stress forcing of May. After attaining full response of the model ocean to southwesterly wind, an idealized cyclone with a maximum velocity of 60 m sec(-1) is superimposed to evolve thermal structure and currents of the coastal ocean. A net decrease of the SST of 6-7 degrees C is simulated when the severe cyclonic storm moves over the coastal ocean.