A pathway for multi-stage cyclone-induced hazard tracking—case study for Yaas

Abstract

A Very Severe Cyclonic Storm "Yaas" developed over the Bay of Bengal (BoB) on May 23, 2021, and crossed over the Odisha coast on May 26 with maximum sustained wind speed of 75 kts. Herein, a pathway has been developed and exempli ed for 'Yaas' through three-stage cyclone-induced hazard tracking. Days before the cyclone formation, Cyclone Genesis Potential Parameter, Sea Surface Temperature (SST) (> 30 0 C) and Tropical Cyclone Heat Potential (anomaly of 40-80 kJ/cm 2 ) indicated a strong possibility of cyclogenesis in the BoB. A Lagrangian Advection Model used for its track prediction with 24-hour lead-time provided an accuracy of ~ 19 km and ~ 6 hour in its landfall location and time. Further, intensity prediction was done using Numerical Weather Prediction model. Geostationary Satellites, INSAT-3D/3DR, were used to visualise cyclone structure.Passing of cyclone had its reverbarations in oceans, which are observed in SST drop of ~ 3 o C, salinity and density increase by ~ 1 psu and ~ 2 Kg/m 3 , respectively. During the period, 23-26 May 2021, the Ekman suction velocity and chlorophyll concentration were found signi cantly high at ~ 5m/day and > 0.5 mg/m 3 , respectively. Forecast of storm surge was found to be between 3.5-4 m at coastal locations. Signi cant wave height was found to be 5.5 to 9.2 m. The coastal inundation forecast for 24 May 2021 provided its quantitative maximum inland extent. Finally, loss of the crop, shery and forest areas by strong winds and inundation/ingress of saline water associated with storm surge were examined using SAR and optical data.