Coupled ocean-atmosphere climate predictability study over South America and the Tropical Atlantic

Abstract

Two elements of the climate system stand out to modulate climate variability over South America: sea surface temperature (SST) over the Tropical and South Atlantic, and atmospheric convection over cool waters, as it is the case with the South America Convergence Zone (SACZ). While dynamic and statistical models are barely capable to predict SST over the South Atlantic better then persistence, atmospheric general circulation models (AGCM) present negative skill to simulate seasonal variability associated with the SACZ. Recent literature indicate the inherent lack of coupled ocean-atmosphere interactions of AGCMs as one of the principal factors to explain the inability of AGCMs to simulate the SACZ behavior. Also, there are indications that SST variability over the Tropical and South Atlantic are 1-D flux driven at the ocean surface. Therefore, it seems appropriate to use coupled ocean-atmosphere models to study seasonal climate variability over South America and SST over the Tropical Atlantic. This research proposal is aimed at studying the seasonal climate predictability over South America and sea surface temperature over the tropical and South Atlantic Ocean using a suite of atmospheric, oceanic and coupled ocean-atmosphere GCM. For that end, it is proposed to carry out a battery of ensemble prediction and simulation numerical experiments making use of the GCMs available at CPTEC. The simulated and predicted ensemble means will be compared against observations both of precipitation over South America and SST over the tropical Atlantic. (AU)