Connection Between Mainland-indochina Monsoon Onset Dates and Cyclones Over Andaman Sea Bay of Bengal Basin

Abstract

Abstract This study delves into the intricate connection between Mainland Indochina Southwest Monsoon (MSWM) onset dates and tropical cyclones (TCs) over the Bay of Bengal (BOB) and Arabian Sea (ABMS). Utilizing datasets like IBTrACS, ERA5 reanalysis, and CHRIPS daily rainfall data, the research highlights the influence of TCs on monsoon onset, emphasizing sea surface temperatures and rainfall intensity. The bimodal distribution of cyclones during early and late-onset years is noted, characterizing MSWM onset by the April-June TC count. Significant correlations emerge between cyclone frequency, monsoon onset dates, SST, and rainfall patterns. Cyclones impact agriculture, water resources, and disaster preparedness in monsoon-dependent regions. Employing a robust methodology, the study reveals a complex relationship between TCs and monsoon onset, with early-onset years experiencing higher TC numbers. Additionally, the research explores the impact of El Niño–Southern Oscillation (ENSO), associating positive phases with late monsoon onset and negative phases with early onset and increased rainfall. The findings underscore TCs' multifaceted role in shaping the monsoon, offering insights into intricate climate variables and cyclone dynamics in the northern Indian Ocean.