Study of accumulated cyclone energy and associated drivers affecting tropical cyclone activities over the North Indian Ocean during the pre- and post monsoon season

This study undertakes a thorough examination of tropical cyclones (TC) and the necessary climatic conditions in the North Indian Ocean (NIO) during the time 1991 and 2020. This period is divided into two segments, with a specific emphasis on the months before and after the monsoon season. It examines the parameters that impact TC development, intensification, and genesis location. Accumulated cyclone energy (ACE) is a crucial metric for quantifying the intensity of a cyclone. Our study analyzed ACE variations and the drivers or parameters affecting cyclogenesis and ACE. Regional dependency of ACE and how it varies with the time and location is studied in our study. Because of the data availability, ACE time is divided into only two periods, 1991–2005 and 2006–2020. A decreasing trend is seen in ACE from 1991 to 2005. Subsequently, it began to increase again, undergoing rapid changes from 2006 until 2020, and is anticipated to boost cyclogenesis in the future. The ACE is broadly distributed and spread over the Bay of Bengal (BoB), with the Main Development Region (MDR) exhibiting higher mean values and more variance when compared with the Arabian Sea (AS). The MDR, which encompasses both the AS and the BoB, is the primary region in the NIO where most cyclogenesis occurs. From 2005 onwards, there was a reduction in the count of TCs, although the ACE has been on the rise. This implies that the cyclones forming in the region are high-category storms. Our study found that more intense cyclones occurred in the October and November months of post-monsoon seasons. Also, a partial correlation between ACE and potential drivers shows that no single parameters affect cyclogenesis, but all the parameters affect ACE somehow. Significant fluctuations in oceanic and atmospheric parameters have been seen in the MDR, contributing to cyclone intensification and high ACE values throughout all periods.