Warm pool dynamics and the tropical glacial climate

One of the most prominent features of the tropical oceans is the existence of warm pools, vast areas of water with relatively homogenous temperatures. The extent to which the tropical warm pools were different in temperature or geographical distribution at the Last Glacial Maximum has been the subject of debate in recent years. Paleoceanographic evidence can provide some guidance on this issue. However, there is little understanding of the processes that control the features of the warm pool, how changes in the warm pool might come about, and how such changes would impact the tropical climate as a whole. In this paper, an array of modeling results is used to advance a simplified framework for understanding the oceanic and atmospheric processes that determine the geographical distribution of the warm pool. It is shown that cloud feedbacks and ocean dynamics are the key processes. Ocean general circulation model results are then used to demonstrate how altered ocean heat transports in the glacial climate can bring about significant changes in the warm pool. Finally, atmospheric general circulation model results are presented which show that changes in the size of the warm pool impact the mean temperature of the tropics via controls on the overall greenhouse effect of the tropical atmosphere.