ON THE OCCURRENCE OF UPWELLING ALONG THE EAST-COAST OF INDIA

A numerical model is applied to simulate the coastal circulation of water off the east-coast of India. The driving mechanisms consist, in general, of wind-stress forcing representative of that applying during the southwest monsoon season, and a forced southward transport of water across a northern open boundary that models the fresh water discharge from the Hugli and Mahanadi rivers. The model predictions (both with and without northern boundary forcing) are compared with recently published data on observations of upwelling along the east coast of India. The simulations provide definitive evidence that, with the simultaneous presence of both a forced fresh water flow and upwelling favourable winds along the east coast of India during the monsoon season, the occurrence of upwelling is confined to latitudes south of Visakhapatnam. To the north of this latitude, it is shown that the local effect of the southward forced transport of fresh water across the northern boundary remains sufficiently strong to inhibit the occurrence of upwelling and, instead, to lead to a sinking that is consistent with the observational data. © 1992 Academic Press Limited.