Inter-annual to multi-decadal climate variabilities in the South Atlantic are investigated using numerical modeling. Two experiments are compared: a coupled NCAR CCM3-Miami Isopycnic Coordinate Ocean Model run, and an ocean-alone experiment in which the surface forcing for the ocean is taken from a CCM3 run with climatological SST. Empirical Orthogonal Function (EOF) and Singular Value Decomposition (SVD) analysis of SST and SLP fields in the coupled simulation reveal patterns very similar to those observed in COADS and NCEP/NCAR reanalysis data. On the other hand, the results of the stand-alone ocean experiment differ from observational data. This suggests that the SST variabilities can not be attributed solely as a passive response of the ocean to atmospheric forcing. During the presentation we will discuss the nature of the coupling between ocean and atmosphere and which physical mechanisms are responsible for the simulated patterns of variability.