Trends and Variabilities of Different Rainfall Intensities Over the West Coast and Central India and Their Association with Global SSTs

In this study, characteristics of summer monsoon rainfall (SMR) are investigated for two regions, West Coast (WC) and Central India (CI), in the Indian subcontinent during 1901–2020. We classified rain events into different intensity bins, viz. dry, low, moderate, high, very high and extreme. SMR in CI exhibits a significant decreasing trend of −5.6 mm season−1 decade−1. Similarly, a significant increasing trend in low and decreasing trend in very high intensity bins are noticed. In WC, the extreme intensity bin shows a significant increasing trend. From the coherence analysis of intensity bins between WC and CI, it is found that the correlation of rain events increased during 1991–2020, especially in extreme intensity bins. Analysis of the relationship of SMR with global sea surface temperature (SST) was carried out. The relationship of WC-rainfall with the Arabian Sea (AS) and the Bay of Bengal (BoB) SST shows significant changes from 1950. The correlation was previously positive but became negative after 1950. CI-rainfall shows a significant positive correlation with the southwest Pacific Ocean (SWPO) SST before 1960, and thereafter it became negative. Extreme intensity bin correlation with the Niño 3 index has changed from 1960 in both WC and CI regions. When the SST variations in various ocean domains are examined, it is discovered that the SST is increasing significantly in the AS, BoB, north central Pacific Ocean (NCPO), Niño 3, SWPO, and north Atlantic Ocean (NAO). In general, recent changes in rainfall and rainfall-SST relationship clearly indicate the climate shift.