Daily rainfall analysis for Indian summer monsoon region

Abstract

A simple method of daily rainfall analysis on a regular latitude by longitude grid over the Indian monsoon region is described. Daily rainfall estimates obtained from INSAT IR radiances and rain-gauge observations are combined to produce this analysis. A case of a typical westward moving monsoon depression during the 1994 monsoon season is chosen to present the characteristics of the rainfall analysed. The results obtained show that the analysis is able to represent adequately the large-scale distribution of the rainfall realized, which can further be used for modelling studies. By inserting rain-gauge observations it is seen that, in general, the final analysis removes the large negative bias imposed by the satellite estimates. Owing to the non-availability of the precipitable water estimates over this region in real time, at present, there is a necessity to have alternative procedures for analysed rainfall distribution, especially for the purposes of physical initialization and other related applications of the tropical numerical weather prediction. When the Special Sensor Microwave Instrument (SSM/I) and other estimates from the Tropical Rainfall Measuring Mission, etc. become available in future the present scheme will be able to include these new products also for improving the quality and representation of rainfall over oceanic region. © 1997 The Royal Meteorological Society.