Coastal upwelling off the southwest coast of India: observations and simulations

Spatial hydrographic data collected from August 2007 through May 2008 and the Princeton Ocean Model (POM) are utilized to explain and document the upwelling in the south eastern Arabian Sea (SEAS). The decrease in the magnitude of winds towards the coast favors local anti-cyclonic vorticity, resulting in the formation of cyclonic eddy and reversal of coastal currents. The Ekman transport due to alongshore winds, Ekman pumping due to wind stress curl, cyclonic eddy and southward West Indian Coastal Currents play different roles in the SEAS upwelling. In the offshore, wind stress curl leads to the formation of meso-scale eddies, resulting in Ekman pumping at the center and consequent upwelling. The rapid depth variation on the western side of Quilon Mount intensifies upwelling in the offshore. The upwelling Kelvin waves generated at the equator terminates in the Bay of Bengal and do not contribute to the SEAS upwelling. The possible role of local and remote winds, especially around Sri Lanka on the upwelling dynamics of SEAS is described utilizing POM. The Kelvin waves generated off the coast of Sri Lanka during the active phase of the summer monsoon also contribute to the upwelling dynamics off the west coast of India.