Variability in Eddy Distribution Associated With East India Coastal Current From High‐Frequency Radar Observations Along Southeast Coast of India

Abstract

AbstractSurface current observations from Indian Coastal Ocean Radar Network installed along the Tamil Nadu coast (southeast India) was used to quantify the mesoscale eddies associated with East India Coastal Current (EICC) during 2014–2017. A flow geometry‐based eddy detection algorithm has been applied to the daily averaged surface current maps and was able to detect and track mesoscale eddies of variable temporal and spatial scales. A total of 51 (27 cyclonic and 24 anticyclonic) eddy events, which lasted for more than 4 days, were identified during this period. Total count of cyclonic eddies exceeded the anticyclonic eddies with a clear seasonal pattern concurrent with the mean flow of EICC. The number of anticyclonic eddies leads in southwest monsoon and spring transition period; however, in fall transition and northeast monsoon period number of cyclonic eddies dominates in line with the poleward and equatorward phase of EICC, respectively. Monthly eddy kinetic energy maps showed a seasonal cycle with highest values in November and April. Monthly maps of the surface current vectors provide the broader picture of the seasonal reversal of currents in February and October and low magnitude offshore flow in the summer monsoon period. The Rossby number distribution along a transect perpendicular to the coast was in the order of O(1) shows the presence of strong submesoscale dynamics in the study domain. A case study of an eddy event conferred significant changes in the biological and physical properties of the coastal ocean derived from satellite data.