Exploring possibility of using the brightness temperature difference between water vapor and thermal channels to estimate monsoon precipitation

The infrared measurements from sensors onboard geostationary satellites are often used to quantify and estimate precipitation, which is one of the most important components of the water cycle. In recent years, emphasis is given on the synergetic use of different satellite sensors by exploiting their advantages and constraining their limitations to better quantify precipitation. We assess plausibility of using the brightness temperature difference between water vapor and thermal infrared channels (WVTD) of MVIRI sensor onboard METEOSAT-5 to estimate monsoon precipitation over the Indian continent. The data for the JJAS of 2003 are used in the present study. We compare our estimates with three different datasets namely, raingauge station data from India Meteorological Department, GPCP 1-Degree Daily (1DD), and TRMM 3B42. The comparisons will be discussed for eleven small study areas which are selected in such a way that they exhibit different geographical and rainfall conditions. We show that WVTD could be very useful in quantifying the convective precipitation and to monitor deep convection. A very good agreement is found among estimates based on WVTD and other three independant datasets. This difference could also serve as an additional constraint while preparing precipitation climatology by merging information obtained from different satellite sensors.