BHARATI S. SABADE’s research while affiliated with India Meteorological Department and other places

India Meteorological Department (IMD) categorises the tropical cyclones (TCs) as cyclonic storm (CS), severe cyclonic storm (SCS), very severe cyclonic storm (VSCS), extremely severe cyclonic storm (ESCS) and super cyclonic storm (SuCS). The long term climatology of TCs in these categories and the trends in frequency and intensity of TCs in these categories developing over the NIO and crossing different coastal regions are limited. Hence a study has been undertaken to analyse the characteristics of genesis and intensification of CDs in the above categories developing over the NIO and crossing different coastal regions based on the data of satellite era (1965-2020). The most intense TCs (ESCS & above) cross the coast maximum over Odisha (ODS) followed by Andhra Pradesh (AP)/Myanmar (MMR) & Bangladesh (BDS) and low intensity TCs (CS/SCS) cross maximum over BDS followed by AP, ODS & Tamilnadu (TN) and medium intensity TCs (VSCS) cross maximum over TN/AP/BDS followed by ODS/West Bengal (WB)/MMR during a year as a whole. While maximum CS/SCS cross BDS, maximum VSCS cross BDS/MMR and maximum ESCS cross MMR coast during pre-monsoon season. While maximum CS/SCS/VSCS cross AP coast, maximum ESCS cross ODS coast during post monsoon season. Over the AS, the landfall frequency of VSCS is maximum over Arabia - Africa (AA) coast followed by Saurashtra and Kutch coast. The coastal vulnerability due to ESCS continues over the Bay of Bengal (BoB) region, as there is no significant trend in the frequency of genesis of ESCS and above intensity storms, though there is decreasing trend in the genesis frequency of D/DD, CS, SCS, VSCS over the BoB. It has increased over the AA coast due to increasing trend in frequency of genesis of VSCS and above intensity storms over Arabian Sea.

A tropical cyclone (TC) is a warm core large scale low pressure system with maximum sustained wind (MSW) of 34 knots or more around the centre which rotates in anti-clockwise direction in Northern Hemisphere and clockwise in Southern Hemisphere. The TCs are most destructive due to the associated storm surge, heavy rain and wind. Indian coast is more prone to TC though the proneness varies from districts to districts (Mohapatra et al., Nat Hazard 63:1601–1620, 2012a; Tropical Cycl Res Rev 1:331–339, 2012b; Mohapatra, J Earth Syst Sci 124:515–526; J Earth Syst Sci 124:861–874, 2015a, J Earth Syst Sci 124:861–874, 2015b). Though there have been significant improvement in the track and intensity forecast of the TCs over North Indian Ocean (NIO) (Mohapatra et al., Nat Hazard 63:1601–1620, 2012a, Trop Cycl Res Rev 01:331–339, 2012b, J Earth Syst Sci 122:589–601, 2013a, Mausam 64:1–12, 2013b, Nat Hazard 68:433–451, 2013c; Mohapatra, J Earth Syst Sci 124:515–526, J Earth Syst Sci 124:861–874, 2015a, J Earth Syst Sci 124:861–874, 2015b), still there are challenges in the unique cases like rapid track change, rapid intensity change etc. Hence there is need for further understanding of physical processes associated with such unique cases of TCs developing over the NIO.