Response of Indian East coast upwelling to river runoff in an OGCM

Abstract

Along the east coast of India (ECI), local winds are oriented alongshore during the summer monsoon, favouring coastal upwelling. The East India Coastal Current (EICC) during this period converges at 17$^{\circ}$N with northward flow from the south and southward flow from the north. A high-resolution Ocean general circulation model (OGCM) which includes runoff from major rivers (RIVER) simulates the upwelling along the east coast of India during the summer monsoon reasonably well. The model simulation shows that the upwelling increases towards south, where salinity influence is lesser compared to the northern parts. The presence of rivers suppresses upwelling, the depth of the source of subsurface water becomes shallow from 100 to 60 m, and reduces the SST cooling by 0.5$^{\circ}$C owing to the increase in stratification of the water column.