THE FLOW-FIELD OFF SOUTHWEST INDIA AT 8N DURING THE SOUTHWEST MONSOONOF AUGUST 1993

The flow field off the southwest coast of India at 8N was investigated during RV Sonne cruise 89 in August 1993 by direct velocity observati ons from shipboard- and lowered-ADCP and geostrophic computations from CTD stations. The upper ocean between 75E and 76 degrees 52'E near th e South Indian shelf was governed by a northward flow with a subsurfac e velocity maximum of 25 cm s(-1) at about 100 m depth. This flow, org anized as a poleward undercurrent hugging the continental slope, is ty pical for the southwest monsoon season. The northward transport in Aug ust 1993 was 4.7 Sv (1 Sverdrup = 10(6) m(3) s(-1)) for the upper 300 m from the shipboard ADCP. Earlier geostrophic observations showed sou thward surface flow above the poleward undercurrent, but in August 199 3 the northward flow reached to the surface and in the geostrophy calc ulations, i.e. without the southward Ekman flow near the surface, ther e was even no clear subsurface core. The T-S characteristics show that Bay of Bengal Water (BBW) was carried with this flow, and low wind co nditions seemed to be connected to the flow of BBW from the southern t ip of Sri Lanka toward the southwest coast of India. Further offshore, two meridional current bands were identified in the upper 300 m of th e ocean. West of the coastal undercurrent a band of southward flow exi sted with velocities up to 35 cm s(-1) above and to the east of the Ch agos-Laccadive Ridge, from 72 degrees 10'E to 75E. The associated geos trophic transport in the upper 500 m was 5.2 Sv. As the T-S relation w as different from that of the northward flow, this current band was no t a local recirculation of the poleward undercurrent. Further west, th e flow was weak, but intensified toward the central Arabian Sea, betwe en 66E and 69 degrees 20'E, where another southward current band was f ound with velocities of up to 20 cm s(-1) and a total geostrophic tran sport for the upper 300 m of -7.2 Sv.