Model for atmospheric corrections to microwave brightness temperature data

The effects of atmospheric liquid water (cloud) and water vapor on the brightness temperature data acquired by Bhaskara-Satellite Microwave Radiometer at 19.1 and 22.235 GHz near the nadir look angle have been discussed in detail. It has been observed that the net contribution to brightness temperature data due to atmosphere is quite considerable over sea and wet land conditions. Two operational quasistatistical models have been developed for doing atmospheric corrections to brightness temperature data, one applicable under cloud-free conditions and the other under all weather conditions. The physical concepts to arrive at these quasistatistical models have been discussed. The constants of the models are estimated by the method of least squares fit by simulating 200 sets of atmospheric and ground conditions. The root mean square errors in the brightness temperature after applying atmospheric corrections are estimated to be 0.5 and 4 K under cloud-free and all weather conditions respectively. A detailed discussion on the validity and applicability of the models is also presented.