Thermohaline and current structure off Cochin during December 1986

Abstract

Time series measurements of surface meteorological elements, vertical temperature and salinity profiles and subsurface currents at selected depths, made at a station off Cochin (depth 65 m), were utilised to describe short-term variability of these parameters during 4-8 December 1986. The vertical temperature profiles were nearly isothermal but showed diurnal perturbations of about 0.5-degrees-C in the upper layers. The salinity structure showed influx of Bay of Bengal/Equatorial Indian Ocean waters carried by the prevailing northerly current. The currents at all depths were northerly against the local wind direction, with speeds over 40 cm.sec-1 at 10 and 20 m depths during the first 2 d. The currents exhibited semidiurnal periodicity indicating predominance of semi-diurnal tide. The vertical current shear was maximum between 10 and 20 m depths which also decreased with the weakening of the flow from 6 to 8 December.