Current structure and volume transport across 12°N in the Bay of Bengal

Abstract

Geostrophic currents and the associated volume transport across 12-degrees-N in the Bay of Bengal during early southwest monsoon (April), southwest monsoon (September) and early northeast monsoon (November) show flow reversal near the east coast of India from April to September. Current structure in November is similar to that in September with a shift in the current bands. Transport in the upper 1000 m between the stations exhibits a reversal west of 83-degrees-E from April to September and cast of 85-degrees-E from September to November. Total geostrophic transport in the upper 1000 m shows an outflux (southward transport) of 3 x 10(6) m3.sec-1 in April and less outflux (< 1 x 10(6) m3.sec-1) in September and a large influx of about 6 x 10(6) m3.sec-1 in November. Total geostrophic transport in the upper 100 m is comparable in magnitude to that of Ekman transport across 12-degrees-N. Total transport (sum of geostrophic and Ekman transports) in the upper 1000 m is comparable in magnitude and direction to the steady Sverdrup volume transport across 12-degrees-N in April and November. In September, while the total transport indicates outflux of about 3.2 x 10(6) m3.sec-1, the Sverdrup transport shows influx of about 5 x 10(6) m3.sec-1.