Equatorial Current Observations in the Western Indian Ocean in 1975 and 1976

Abstract

Vertical profiles of current, temperature and salinity were taken in the upper ocean from 3°S to 2°N along 55°30?E in the Indian Ocean during February?June in 1975 and 1976. During both years a strong O(80 cm s?1) equatorial undercurrent was present throughout the measurement period in the vicinity of the equator. A second region of eastward flow above the thermocline was observed at 3°S. During May and June the undercurrent moved southward and merged with the southern region of eastward flow. The meridional flow field was dominated by transients that during strong events were antisymmetric about the equator and had a vertical wavelength of ?180 m. The transient events strongly affected the zonal flow field; during strong events the undercurrent was almost eliminated. This is in contrast to the GATE observations where the undercurrent was advected back and forth across the equator.