Thermodynamic and dynamic effects on regional monsoon rainfall changes in a warmer climate

This study investigates thermodynamic and dynamic effects on regional monsoon rainfall changes in a warmer climate, by using 20 climate model outputs in the Coupled Model Intercomparison Project (CMIP) Phase 5. In a warmer climate, rainfall is projected to increase in most monsoon regions. However, the rates of increase are quite different among the monsoon regions. A diagnosis based on a linearized moisture budget equation reveals that the regional differences of the rainfall change are largely explained by differences in the dynamic effect. In the Asian monsoon regions, monsoon circulation slows down at a much lower rate than in the other monsoon regions; in addition, surface evaporation increases at a higher rate, resulting in a much larger increase in rainfall. These features are commonly found in both CMIP Phase 3 and Phase 5 model projections.