Physics of North Indian Ocean tropical cyclones.

This research paper focuses on the applicability of two well-known concepts, Convective Quasi Equilibrium (CQE) and Convective Instability of the Second Kind (CISK), in the genesis of tropical cyclones (TCs), over the North Indian Ocean (NIO). Using high-resolution regional reanalysis IMDAA data from NCMRWF, we study the applicability of CQE and CISK during pre-monsoon (April and May) and post-monsoon (October and November) for the 1979 to 2020 period. In this study we found that CQE seems to be applicable over some regions of Arabian Sea (AS) in the pre-monsoon season only. However, TCs form over the entire AS, thus CISK mechanism may be vital in pre-monsoon over the AS. In post-monsoon season, over the Bay of Bengal (BB), CQE is found to be applicable. Also, we found the applicability of the CISK, over the BB, both in the pre- and post-monsoon seasons. The study of individual TCs confirms these results regarding the genesis mechanisms of TCs over NIO. Another important, feature we discovered over the AS is the strong, diurnal variation of humidity.