Tropical rain belt and energy budget: a regional approach using TRACMIP

Tropical Rain belts with an Annual cycle and a Continent-Model Intercomparison Project (TRACMIP) is designed to help answer the Grand Challenge question of what controls the tropical rain belts. To understand tropical rainfall changes, the vertically integrated atmospheric energy budget has been used for over 30 years. It relates tropical rainfall to the radiative forcing throughout the whole atmosphere. Recently, the analysis using energy budget showed the remote link between meridional intertropical convergence zone (ITCZ) shifts and high-latitude thermal forcings. These ideas focused on the relationship between zonal mean ITCZ position and zonal mean meridional atmospheric energy transport, but were found inapplicable at smaller temporal and regional scales. Our analysis of TRACMIP outputs will test if the zonal mean framework can explain the model disagreements on ITCZ shifts at annual and seasonal time scales.

With a localized continent, TRACMIP can also help us understand regional precipitation changes. Using more recent theories, we aim to take zonal energy transports into consideration in addition to meridional transports to quantitatively explain the seasonal and regional rainfall response to different forcings. Understanding of temporal and regional responses in TRACMIP can give insight into real-world precipitation change under a warming scenario.