Response of quick scatterometer wind forcing on the ROMS simulation during 'MALA' cyclone

摘要

Tropical cyclones are form of intense storms which are common in the Bay of Bengal (BOB) and known for their damage potential to human and natural resources especially in the coastal parts of India, Bangladesh and Myanmar. A two-way effect is prominent between BOB's sea surface temperature (SST) and these cyclonic events. On one side, BOB's high SST favours formation of cyclones and on the other side it itself gets affected whenever cyclone occurs. The later part along with circulation patterns has been simulated here with the help of high resolution Regional Ocean Modeling System (ROMS) for 'MALA' cyclone. Remote sensing instrument Quick Scatterometer (QuikSCAT)-derived daily wind components are used as atmospheric forcing conditions for ROMS simulations. ROMS circulation is found highly sensitive towards QuikSCAT wind forcing and reveal an anticlockwise rotation with high magnitude currents due to cyclone passage. Near surface as well as deeper isotherm and isohaline surfaces show high degree of spatial variability and overall indication of upwelling happening on near track area. It is found that mixed layer depth reduces at the storm centre due to intense upwelling but increases far away from it because of high winds. Due to intrusion of bottom high saline water and reduction of temperature, density increases from its initial value which affects water column stability from surface to even below 150 m depth.