Study of Upwelling along the West Coast of India-A Climatological Approach

With extensive use of satellite-measured climatology, the present study investigated the upwelling along the entire west coast of India and authenticated the differences in upwelling along the SW and NW coasts. During May and September, the entire west coast of India was characterized by weak offshore surface mass transport. During June, July, and August, offshore surface mass transport was limited to SW coast of India, and onshore transport was observed along NW coast, except at 16 degrees N and 17 degrees N, where very weak offshore transport was observed, compared with SW coast. Analysis of the Sea Surface Height Anomaly, depth of 26 degrees isotherms, and Local Temperature Anomaly revealed the role of remote forcing on the upwelling along the west coast of India, especially during the peak summer monsoon months. The observations on the Local Temperature Anomaly at different depth levels exposed that, at the surface, the upwelling features was limited to the SW coast of India during the summer monsoon. Upwelling, however, was clearly evident at the 10-m depth along the NW coast during May and September. The main difference in upwelling along the SW and NW coastlines during June to August was that vertical excursion of upwelled water along the NW coast was limited to the 30-m depth and along the SW coast; the upwelled water replaces the surface water. From Local Temperature Anomaly it was also evident that the intensity and south to north propagation speed of upwelling was more at deeper level than at the surface.