Validation of satellite estimated convective rainfall products : A case study for the summer cyclone season of 2020

Abstract

The present work is focused on the performance of convective rainfall products, derived from Meteosat-8 (IODC) at NCMRWF using GFS first guess fields during summer cyclone season 2020. NCMRWF receives Meteosat-8 (IODC) HRIT data in real-time through EUMETCAST terrestrial service. NCMRWF derives the nowcasting products, including Convective Rainfall Rate (CRR), RGB products and cloud imageries in real-time and made available to IMD through the National Knowledge Network (NKN). Here, we focussed on the Amphan and Nisarga cyclones, formed in the Bay of Bengal and the Arabian Sea respectively. The validation of these CRR products is carried against calibrated and merged precipitation product IMERG by GPM missions. Grid to grid comparison of both precipitation products shows a good agreement in convective cloud regions in both the cyclones. Probability of Detection (POD) and Critical success index is very high (~1) in the precipitating clouds region. POD, Success ratios are very high (~1) in the regions of moderate, intense, very intense spells during the two cyclones. The POD is low for light spell (0-10 mm/h) regions. This is expected from CRR a ‘convective cloud’ specific product, which filters out rainfall in stratiform cloud regions. This study shows that CRR can be used in near-real time rainfall monitoring for various applications.