STUDY OF AIR-SEA INTERACTION PROCESSES OVER THE ARABIAN-SEA AND THE BAY-OF-BENGAL USING SATELLITE DATA

The main objective of this work is to study the latitudinal and season al variation of latent heat fluxes (LHF) and associated atmospheric an d oceanic parameters over the Arabian Sea (AS) and the Bay of Bengal ( BB) for the year 1988. The atmospheric and oceanic parameters, like pr ecipitable water(PW),ocean surface wind(WS), and cloud liquid water co ntent, are derived from the Special Sensor Microwave/Imager (SSM/I), a nd SST is obtained from the National Oceanic and Atmospheric Administr ation's Advanced Very High Resolution Radiometer. The latent heat flux es have been estimated from the bulk aerodynamic formula using the abo ve satellite-derived parameters. The surface-level humidity, an essent ial parameter required for computing LHF, has been estimated using Liu 's global relation between monthly mean surface-level humidity and pre cipitable water. A comparison of these variables and the relation amon g them has also been made over the AS and the BB. A significant latitu dinal variation is observed in LHF for most of the months over the AS and the BB, while other oceanic and atmospheric parameters are charact erized by a strong latitudinal variation in nonmonsoon months. Seasona l variations in LHF are more significant at higher latitudes compared to lower latitudes over the AS and the BB. The effect of coastal upwel ling near the Somali coast decreases LHF, while surface winds near the Indian coast during monsoon months increases LHF. A comparative study over the AS and the BB demonstrates higher PW and SST over the BB tha n over the AS. LHF is found to be greater over the AS than over the BB for nonmonsoon months. Correlation analysis indicates that LHF is fou nd to be highly correlated with DQ (difference between the humidity at the surface and humidity near the surface) over the AS and weakly cor related over the BB during nonmonsoon months. Throughout the year, DQ is found to be a dominant factor for LHF over the AS. However, WS exer cised better control over the BB in generating LHF. SST and PW are fou nd to be highly correlated with each other over the AS (r = 0.87) and the BB (r = 0.75) for nonmonsoon months. The correlation becomes weakl y negative over the AS (r = 0.15) and weak over the BB (r = 0.26) duri ng monsoon months. Precipitable water is found to have a high correlat ion with WS over the AS (r = 0.72). This unique feature is revealed by SSM/I data and has not been reported earlier due to paucity of data o ver this region.