Evolution of a Sub-Mesoscale Eddy Leeward of Andaman Islands from HF Radars

Abstract

Remotely sensed high-resolution ocean surface currents from high-frequency radars (HFRs) on the western Andaman Sea (AnS) reveals signature of a sub-mesoscale coastal anticyclonic eddy leeward of Little Andaman (LA) Island during August 4-9, 2017. This 'Lee eddy' had a mean radius of 11 km, negative values of normalized vorticity, divergence, and Okubo-Weiss (OW) parameter, and smaller values of strain. A term-by-term vorticity budget analysis suggests that the vortex stretching term and wind stress curl dominate during the evolution and demise of the Lee eddy than does advection.