A two-frequency logarithmic differential technique for retrieving precipitable water from the satellite microwave radiometer (SAMIR-II) on board Bhaskara II

The use of the logarithmic differential signal of 19.35 and 22.235 GHz as a predictor of water vapor retrieval is demonstrated. This technique minimizes the effects of wind speed and clouds on the retrieval due to the close proximity of the two channels. The method provides a 44 percent improvement over the general regression approach, which uses brightness temperature as a predictor. It also provides an alternative approach to the use of the logarithmic function of brightness temperature as a predictor. The approach has been used to study the summer and winter water vapor distribution over the Arabian sea, and the results are presented.