Perspective Chapter: The Coastal Migration of the Locations of Tropical Cyclone Rapid Intensification over the North Indian Ocean

Abstract

The migration of maximum intensity poleward is triggering a shift in the rapid intensification (RI) locations of tropical cyclones (TC) towards the coast of ocean-rim countries. The study investigates changes in the distribution of locations of RI during the pre-monsoon and post-monsoon seasons in recent warming climate scenarios over the North Indian Ocean (NIO) basin. Over the Bay of Bengal (BOB), the percentage of annual RI TC frequency exhibits a stable or slightly decreasing trend (20–100%), contrasting with a notable surge (50–100%) over the Arabian Sea (AS) in recent years. The distribution of RI TC location gradient is meridional during the pre-monsoon season and is confined zonally below 15°N during the post-monsoon season over BOB. The corresponding locations over AS are confined between 10°N–15°N and 12°N–17°N latitudinal regions. An inverse relation between the simultaneous rise in SST and RH550 is evident during the pre-monsoon season, while the relation fails during the post-monsoon season over BOB. While sea surface temperature and mid-tropospheric relative humidity play a crucial role in RI, the observed changes in tropospheric vertical wind shear patterns and upper-level divergence alignment in current climate conditions are identified as influential factors shaping the distribution of RI location over BOB and AS.