Hydrography and circulation of the Bay of Bengal during early winter, 1983

Abstract

The large-scale circulation and the distributions of temperature, salinity and density in the Bay of Bengal during early winter (October-–December 1983) are presented. The surface circulation relative to 1000 db level surface indicates a northward flowing eastern boundary current from north of 8°N west of the Andaman-Nicobar Islands and, to its west, a large cyclonic gyre between 19° and 13°N. The wind stress curl for November suggests that this gyre is primarily wind driven. The north-flowing eastern boundary current of the Bay of Bengal is fed by the monsoon drift current during late October. This eastern boundary current extends up to 19°N and merges with the cyclonic gyre. The southwestward flow of the cyclonic gyre along the central east coast of India is strengthened by the freshwater discharge from the northern part of the Bay. Warm and saline equatorial waters advect northward through the eastern boundary current, which coupled with the process of winter cooling at the head of the Bay leads to sharp temperature inversions (about 2°C) at 50 m depth in the north-northwestern Bay. The volume transport associated with the eastern boundary current across 12°N between 88° and 92°E 6 × 10 6m 3s −1 in the upper 200 m.