The Upper Branch of the Atlantic Meridional Overturning Circulation modulated by the Tropical Atlantic Dynamics

Abstract

The upper branch of the Atlantic Meridional Overturning Circulation, in the equatorial area, is mostly contained in the western boundary as the North Brazil Current. Downstream that current, there are two main pathways, a long one through North Equatorial Counter Current, and a short one that includes the North Brazil Current Rings. Half of the inter-hemisphere transport is accounted to those rings, which are believed to be triggered by short Rossby Waves associated to the North Equatorial Counter Current. Following up, the North Equatorial Counter Current is controlled by the injection of vorticity into the ocean by the wind on regional scale. Since the wind has an interannual variability component, it is reasonable to believe that Atlantic Meridional Overturning Circulation, as well as the North Brazil Current Rings, also has such interannual variability. The transport due the North Brazil Current Rings is better preserved for long distances by its dynamic insulation due the vortical shield, hence, differing from an equivalent transport by a mean current. We thus propose to quantify the relationship between the wind variability in the Tropical Atlantic and the patterns of the North Brazil Current Rings, using in situ observations and remote sensing. Following that, it will be evaluated if such processes are properly reproduced by the new generation of high-resolution global models, and its effects on the quality of such simulations.