The Seasonal Cycle of Meridional Currents in the Upper Layers of Central Equatorial Indian Ocean: Observations and Dynamics

The meridional currents in the upper layers of the Indian Ocean play an important role in the general circulation as a major conduit for mass, heat, and salt transfer between the Northern and Southern hemispheres of the basin. The mean seasonal cycle of these currents is unique compared to other tropical oceans because of very strong seasonally reversing monsoon wind forcing. Describing and understanding these currents has been hindered by a lack of direct velocity measurements of sufficient length to provide reliable estimates of the mean seasonal cycle. In this presentation we will describe the annual mean and seasonal variations in meridional current and volume transport in the upper ocean based on five years of measurements from a meridional array of Acoustic Doppler Current Profilers spanning 2.5°N to 4°S along 80.5°E in the center of the basin. The dynamics of these currents and their time dependent adjustment to monsoon transition wind forcing will be highlighted.