Temporal Variability of the South Atlantic Meridional Overturning Circulation between 20°S and 35°S

Satellite altimetry measurements are used to investigate the spatial and temporal variability of the Meridional Overturning Circulation (MOC) and Meridional Heat Transport (MHT) in the South Atlantic. Altimetry-derived synthetic temperature and salinity profiles between 20S and 34.5S are used to estimate the MOC and MHT, which compare well with estimates obtained from XBT measurements. Consistent with studies from XBTs and Argo data, both the geostrophic and Ekman contributions to the MOC exhibit strong annual cycles, and play an equal role in the MOC seasonal variations. The strongest variations on seasonal and interannual time scales in our study region are found at 34.5°S. The dominance of the geostrophic and Ekman components on the interannual variations in the MOC and MHT varies with time and latitude, with the geostrophic component being dominant during 1993-2006 and the Ekman component dominant between 2006-2011 at 34.5°S.