Onset and Evolution of Upwelling along the West Coast of India

Abstract

To describe the onset and evolution of upwelling along the south west coast of India, authors collected a series of conductivity temperature depth measurements on board INS Sagardhwani extending from 7 °N – 15 °N during the period extending from February 2017 - October 2017. In this paper we utilised the undulations of the 23 °C isotherm as a proxy to study the upwelling phenomenon. The upward movement of the waters at the southern tip off India (77.5 °E) in the subsurface levels was observed to commence from late February 2017 in depths around 80 m and by the end of May 2017, it is observed to rise rapidly to the surface. The upwelled waters reach the surface during the 2nd week of July all along the Indian coast, and then intensified during August 2017. Beyond 12 °N maximum upwelling is seen in July and thereafter in early August 2017 upwelling was intense till October 2017.