What Caused the Large-scale Heat Deficit in the South Atlantic Ocean during 2009-2012?

The subtropical South Atlantic hosts complex ocean circulations that collectively transport heat to the North Atlantic, and thus plays an important role in global energy redistribution. Observations are key to our understanding of the driving mechanisms of ocean heat changes. This study uses several oceanic products to examine ocean heat changes in the subtropical South Atlantic and the associated atmosphere-ocean processes, with a particular focus on a large heat deficit occurred during 2009-2012, which is associated with cooling during 2008-2011 and subsequent warming during 2012-2013. This heat deficit was largely driven by an oceanic heat transport divergence increase from 2008 to 2011, particularly by an anomalous southward Ekman transport across 35S. The anomalous Ekman transport is tied to the persistent positive sea level pressure anomaly over the Atlantic side of the Southern Ocean, contributed by both the Southern Annular Mode and the remote forcing from the central tropical Pacific cooling.