Sensitivity of brightness temperatures to the oceanic surface roughness and rainfall for TRMM and IRS-P4-MSMR radiometric channels over the Indian Ocean

Abstract

Upwelling microwave radiances at the top of the atmosphere originate partly from the oceanic/land surfaces and partly from atmospheric constituents. Radiative transfer simulations have been carried out for the Tropical Rainfall Measuring Mission (TRMM)-Microwave Imager (TMI) and Indian OCEANSAT-Multichannel Scanning Microwave Radiometer (MSMR) radiometric frequencies for varying winds, under clear sky (non-raining) and raining conditions. Both emission and scattering based radiative transfer simulations are carried out for typical atmospheric profiles over the North Indian Ocean during the monsoon season. The simulation results match reasonably well with the real observations from TRMMTMI and MSMR channels that represent a variety of oceanic and atmospheric conditions during the south-west monsoon season. The main purpose of simulations is to delineate the frequencies that are most sensitive (as far as brightness

temperatures are concerned) to the ocean surface and rainfall characteristics. This effort will contribute for the combined use of different sensors to retrieve geophysical parameters with better accuracy.