Oceanic Inter-hemispheric Exchanges: Tropic-Extratropic Conecctions in the South Atlantic - Analyses of Observations and Numerical Results

Abstract

The main objective of the South Atlantic Meridional Overturning Circulation (SAMOC) project (supported by FAPESP, Proc. 2011/50552-4) is to study the variability of the Meridional Overturning Circulation in the South Atlantic. One specific goal is to develop a numerical study of the Atlantic circulation with an ocean model forced with NCEP/NCAR reanalysis products. At present, two simulation have been completed as part of the CALSA project, also support by FAPESP (Proc. 2010/01943-8). The first simulation has horizontal resolution of 1/4 degree and 22 isopycnal layers, corresponding to the region: 98ºW-114ºE and 65ºS and 60ºN. The second one, with horizontal resolution of 1/12 degree and 22 layers, is a nested run in the region 65ºW-40ºE, 55ºS-20ºN, using the results of the lower resolution run as initial and boundary conditions. In agreement with recent studies, the numerical results show changes in the South Atlantic and Indian Oceans "super-gyre" with an increase of the intrusion of warmer and saltier waters from the Indian ocean into the Atlantic, carried by Agulhas Rings: the Agulhas "leakage". The numerical results also show variations in the Atlantic Meridional Overturning Circulation (AMOC) and the meridional heat flux. In her work, the post-doc fellow will explore the impact of the increased Agulhas leakage on the circulation of the Tropical Atlantic and on the inter-hemispheric exchange of heat and mass. The study will be based on the analyses of the two numerical output and observational data including satellite products, and in situ data from Argo, PIRATA, ATLAS-B and the SAMOC projects.