Refining our understanding of surface currents in the southeast Indian Ocean

The Indian Ocean has many unique characteristics not found in other oceans (Schott and McCreary 2001, Schott et al. 2008; McPhaden et al. 2009). Not least of all is the fact that near-surface eastward currents flow against the predictions of wind-driven Sverdrup and Ekman transports, extending all the way from Madagascar to Australia (Menezes et al. 2014). There are near surface eastward flows in other basins, but none extending so strongly to the eastern boundary. The eastward flows are driven by a meridional density gradient (Furue et al. 2013; Benthuysen et al. 2014) that is enhanced by the presence of warm, fresh Indonesian Throughflow (ITF) Water in the north. This low-latitude connection to the Pacific Ocean is another unique feature of the Indian Ocean and one that has a profound impact on the Indian Ocean circulation.