Synoptic and dynamical characteristics of super cyclone Amphan

Abstract

This study has been undertaken to find out the synoptic and dynamical conditions those have helped in the genesis and intensification of tropical cyclone Amphan. It has been found that, under favourable conditions of high SST, high energy and weak vertical shear of horizontal wind, the 200 hPa STWJ has helped in the genesis of Amphan. The weak vertical shear, the high-temperature gradient between warmer sea surface & colder atmosphere and strong upper-level divergence has increased the heat and moisture exchange between the sea surface and the atmosphere via surface heat fluxes and vertical winds and enhanced the convection and intensified the system. Abnormally high SST (on 17th May) and combined effect of strong upper-level divergence, lower level convergence and low wind shear may be the reason behind the rapid intensification of Amphan. The interaction with 400 hPa trough has also intensified Amphan. This trough and upper-level jet have guided Amphan in its trajectory.