Argo & Altimetry


Transport in the upper branch of the
South Atlantic Meridional Overturning Circulation


The Meridional Overturning Circulation (MOC) plays an important role to the global heat and salinity budgets and is also believed to be linked with climate paprameters such as railfall and surface air temperature in the northern hemisphere. There is increasing evidence that the South Atlantic may be playing a crucial role to the MOC variability. However, compared to the North the the South Atlantic is poorly sampled. Therefore, in an attempt to understand the variability of the upper branch of the Meridional Overturning Circulation in the South Atlantic, a three dimensional absolute velocity product is constructed using sea surface height measurements from satellite altimetry, observations from Argo floats, and wind fields between 2000 and 2014. These velocity fields along with the temperature profiles are then used to estimate meridional volume and heat transport at four different latitudes (20°S, 25°S, 30°S, and 35°S) in the South Atlantic (Majumder et al., 2016).

(a) Meridional volume transport in the upper 400m in the South Atlantic using Argo observations and satellite altimetry, the dotted lines are the sections across 20°S, 25°S, 30°S, and 35°S where the strength of upper branch of the MOC is estimated.

(b) Time series of the MOC strength at 35°S.