A cold pool south of Indo-Sri-Lanka channel and its intrusion into the Southeastern Arabian Sea during winter

During winter, south of the Indo-Sri Lanka Channel (ISLC), the observed sea-surface temperature (SST) distribution shows a distinct mini-cold pool (MCP) with relatively cooler waters (SST < 28 degrees C). All the available satellite and in-situ measurements are utilized to characterize and explain the mechanisms that govern the evolution of the observed MCP. During December-January, the northeasterly surface winds blow through the ISLC manifesting a patch of strong winds in the south with peak intensity of about 10m/s, enhance surface turbulent heat losses and drive near-surface vertical mixing resulting in the observed cooling. The vertical temperature profiles in this region also show cooling and deepening of the near-surface isothermal layer from November to January. This cooling occurs episodically on an intra-seasonal time scale with a typical periodicity of 8-15 days and is stronger when the surface winds intensify, surface net heat losses are larger and the near-surface circulation is more pronounced. The cooling episodes varied in number, intensity, duration and spatial extent in each winter during 1998-2006. The cooler surface waters from this MCP flow initially southwestward and are then topographically steered northwestward by the Maldives Island Chain. The resultant near-surface circulation also appears to strengthen the amplitude of the near-surface thermal inversions observed in the SouthEastern Arabian Sea (SEAS). (c) 2008 Elsevier Ltd. All rights reserved.