Estimation and evaluation of rainfall from INSAT-3D improved IMSRA algorithm during 2018 summer monsoon season

Abstract

Indian National Satellite System (INSAT) multi-spectral Rainfall Algorithm (IMSRA) is an operational rainfall estimation technique of INSAT-3D at Indian Meteorological Department (IMD) and Meteorological and Oceanographic Satellite Data Archival Centre (MOSDAC) since 2014. The IMSRA rain estimates are widely used for various application studies. This algorithm is based on an empirical power-law relation between infrared brightness temperature and surface rain rate. Based on further researches, some more innovative elements are recognized and incorporated into the parent IMSRA algorithm, termed as improved IMSRA. The present study evaluates the potential of the two versions of IMSRA algorithms for estimation of accumulated rainfall and its comparison with Global Precipitation Measurement (GPM) based IMERG rainfall during the 2018 summer monsoon period. Studies suggest satellite rainfall data at monthly and seasonal scales are better suited for hydrological and meteorological applications. Much studies are not done towards the evaluation and characterizations of the two versions of IMSRA algorithms at monthly and seasonal scales, and the present study focuses on such comparisons. The results indicate that the overestimation tendencies of the older version of the IMSRA algorithm are reduced in the improved version. The statistical analysis suggests that the updated version show a reduction ~25% error for the improved version in the seasonal estimation of rainfall.