This process is called a negative feedback. The positive feedback then acts to enhance this reversed SST pattern. If the tropical Atlantic variability can indeed be described as a self-sustaining oscillation, then there is a good possibility that this variability can be predicted using a computer model that captures the essential physics of the oscillation. The predictability follows simply from the fact that a cycle is sequential, and therefore one part of the cycle must follow another. The possibility of predicting low-frequency SST variability in the tropical Atlantic region has long been a central concern because of its significant influence on rainfall over northeast Brazil and the Sahel region of Africa.
Rainfall changes in both areas have an extraordinary economic and societal impact.
Major swings in decadal climate have a significant impact on the economies and societies of the Sahel region of Africa and northeastern Brazil. We model atmospheric behavior by statistically relating historical patterns of sea-surface temperature to corresponding patterns of wind. The ocean model is based on first principles of physics. It uses mathematical equations based on the laws of conservation of mass and momentum. The results are then further processed by a computer to display graphics.