The South Atlantic and the Atlantic Meridional Overturning Circulation

This article discusses the contribution of the South Atlantic circulation to the variability of the Meridional Overturning Circulation (MOC). The South Atlantic connects the North Atlantic to the Indian and Pacific oceans, being the conduit through which the southward outflow of North Atlantic Deep Water (NADW) is compensated by northward inflows of upper and intermediate waters. This circulation pattern, in which cold waters flow poleward and warm waters equatorward, generates a distinct heat flux that is directed from the poles towards the equator. Observations and models indicate that the South Atlantic is not just a passive conduit but that its circulation influences significantly the water mass structure of the Atlantic Meridional Overturning Circulation (AMOC). These transformations occur across the whole basin but are most intensified in regions of high mesoscale variability. Models and observations also show that the South Atlantic plays a significant role in the establishment of oceanic teleconnections. Anomalies generated in the Southern Ocean, for example, are transmitted through inter-ocean exchanges to the northern basins. These results highlight the need for sustained observations in the South Atlantic and Southern Ocean, which, in conjunction with modeling efforts, would improve the understanding of the processes necessary to formulate long-term climate predictions.