Impact of convective organization on the response of tropical precipitation extremes to warming

This study examines the response of tropical precipitation extremes to warming in organized convection using a cloud-resolving model. Vertical shear is imposed to organize the convection into squall lines. Earlier studies show that in disorganized convection, the fractional increase of precipitation extremes is similar to that of surface water vapor, which is substantially smaller than the increase in column water vapor. It has been suggested that organized convection could lead to stronger amplifications of extremes with warming. But regardless of the strength of the shear, amplifications of precipitation extremes in the cloud-resolving simulations are comparable to those of surface water vapor, and are substantially less than increases in column water vapor. A scaling is used to evaluate the thermodynamic and dynamic contributions to precipitation extremes changes. To first order, they are dominated by the thermodynamic component, which has the same magnitude for all shears. The dynamic contribution plays a secondary role, and differs for different shears. These different dynamic contributions for different shears are due to different responses of convective mass fluxes in individual updrafts to warming.