The distribution of rainfall across the tropics has life-or-death implications for billions of people. Tropical rainfall may change as the globe warms, but there is a little agreement among global climate models as to what these changes will be. Tropical rainfall is governed by complex interactions between the large-scale atmospheric circulation and small-scale convection and between the large-scale circulation and the land surface and marine boundary layer. Neelin and his group will use a hierarchy of numerical models, ranging from full global climate models, to idealized models of the tropical atmosphere, to simple diagnostic models, together with formerly under-used observational data to address four fundamental problems important for tropical rainfall: i) how does tropical rainfall change under global warming? ii) how reliable is his quasi-equilibrium hypothesis for explaining the structure of the tropical atmosphere, and what are the implications of this hypothesis for the large-scale circulation? iii) how is moist energy transported in the tropical atmosphere, and what determines the stability of the atmosphere to convection? iv) how does the circulation of a moist atmosphere transmit information from one region to another?
Broader impacts of this research are in its potential to improve models used to forecast tropical weather and climate, in leading to improved projections of how tropical precipitation will change as climate changes, and in training graduate students and post-doctoral research scientists.
