Response of the equatorial Indian Ocean to an unusual wind event during 1994

Abstract

Unusual westward wind anomalies were observed in the Indian Ocean during 1994. The response of the ocean to these anomalies is studied using an ocean general circulation model forced with interannual winds. Model results show that the eastward equatorial jets in the Indian Ocean were weak during 1994. Consequently, the sea level in the eastern Indian Ocean was unusually low, the thermocline and the mixed layer were shallow, and the subsurface flow remained eastward throughout the year. Anomalies of sea surface temperature (SST) and sea level in the eastern Indian Ocean were enhanced by upwelling favorable winds along the coast of Indonesia. The model results agree with observations and TOPEX/POSEIDON data. We suggest that the dynamical response of the ocean to wind anomalies played a role in generating the SST anomalies during 1994 and enhanced the large-scale air-sea interaction, independent of the El Nino Southern Oscillation.