This U.S.-Brazil Cooperative Science award will support travel to Brazil for Rainer Bleck of the University of Miami, along with a graduate student, in collaboration with Edmo Campos of the University of Sao Paulo, Brazil. The project aims to study, in a numerical framework, dynamic and thermodynamic processes governing oceanic circulation in the tropical Atlantic. The model to be used is the thermodynamically active version of the Isopycnic Coordinate model developed at Miami by Bleck and others. The model's main advantage in this context will be to eliminate inadvertent, numerically induced vertical heat diffusion. The researchers also plan to conduct a comprehensive study of the oceanic response to atmospheric thermodynamic forcing. They will also focus on the main interannual and decadal variability signal, commonly called the "Atlantic SST dipole." The U.S. side will benefit from access to equatorial phenomena of water mass exchanges, which will add significantly to the U.S. models of circulation in the North Atlantic. The Brazilian side will gain an enhanced capability in ocean modeling, which will position the country to contribute to future research on global climate change.