Possible factors for the recent changes in frequency of central Indian Summer Monsoon precipitation extremes during 2005–2020

Abstract

The transitions of short-term trends of Indian Summer Monsoon daily precipitation extremes remain poorly understood. Here, we show a short-term declination of temporal frequency of monsoonal precipitation extremes over Central India for the last 15 years starting from 2005 to 2020 while the low and moderate events show increasing trends. The possible dynamical and thermodynamical factors for the observed decline in precipitation extremes include depletion in moisture transport to Central India via cross-equatorial flow and the low-level Somali jet, caused by reduced evaporation from the regional moisture sources. In addition, the vertical gradient of the moist static energy exhibits favorable conditions for increased lower atmospheric stability, supporting the declining trends. Lastly, the Atlantic Zonal Mode seems to be a potential large-scale climate driver for the less frequent central Indian extreme rainfall events during 2005–2020.