Thermohaline structure and circulation in the upper layers of the southernBay of Bengal during BOBMEX-Pilot (October-November 1998)

Hydrographic data collected on board ORV Sagar Kanya in the southern Bay of Bengal during the BOBMEX-Pilot programme (October - November 1998) have be en used to describe the thermohaline structure and circulation in the upper 200 m water column of the study region. The presence of seasonal Inter-Tro pical Convergence Zone (ITCZ) over the study areal typically characterized with enhanced cloudiness and flanked by the respective east/northeast winds on its northern part and west/southwest winds on its southern part, has le d to net surface heat loss of about 55 W/m(2). The sea surface dynamic topo graphy relative to 500 db shows that the upper layer circulation is charact erised by a cyclonic gyre encompassing the study area. The eastward flowing Indian Monsoon Current (IMC) between 5 degrees N and 7 degrees N in the so uth and its northward branching along 87 degrees E up to 13 degrees N appea r to feed the cyclonic gyre. The Vessel-Mounted Acoustic Doppler Current Pr ofiler (VM-ADCP) measured currents confirm the presence of the cyclonic gyr e in the southern Bay of Bengal during the withdrawing phase of the southwe st monsoon from the northern/central parts of the Bay of Bengal.