Validation of cloud mask product from multi-channel satellite INSAT-3DR

Abstract

The Indian National Satellite-3DR (INSAT-3DR) provides half-hourly multispectral images over the Indian region from a geostationary position. It observes diurnal variations highly relevant for variety of application areas, including weather forecasting. This work assesses the performance of the cloud mask product of INSAT-3DR new algorithm developed by Indian Space Research Organization (ISRO) by comparison with Moderate Resolution Imaging Spectrometer radiometer (MODIS) cloud mask data for the months from July 2019 to July 2020. The cloud detection algorithm employs nine different tests, considering solar illumination, satellite angle and surface type conditions to get pixel-resolution cloud mask. Our validation results indicate that the probability of detection (POD) of cloudy (clear) sky is 86 % (82 %) with 83 % hit rate for INSAT-3DR cloud mask, using MODIS cloud mask as a reference. When the INSAT-3DR cloud mask algorithm is also implemented on similar channels of MODIS, the POD of cloudy (clear) sky is 76 % (74 %) with 85 % hit rate. Our findings indicate the reliability of the INSAT-3DR cloud mask retrieved product for research and other applications. This is one of the important parameter of satellite derived products, which plays major role in daily operational weather forecasting.