Extreme precipitation under global warming: manifestation and mechanism

November 15, 2022

Ji Nie

Hosted by Department

Abstract

Responses of extreme precipitation to global warming are of great importance to society and ecosystems. In this talk, we demonstrate several significant manifestations of climatic responses of extreme precipitation and the underlying mechanisms. We first introduce recent advances in understanding the regional patterns of extreme precipitation sensitivity by the dry and moist decomposition. By applying Quasi-Geostrophic diagnostics, extreme precipitation may be separated into components due to dry (large-scale adiabatic flow) and moist (small-scale convection) dynamics, and so is the climatic response. We derived a theoretical model that depicts a nonlinear dependence of the diabatic heating feedback on precipitable water and the climatic responses, thus largely explaining the regional patterns of extreme precipitation sensitivity. We then introduce a robust expansion (consistent among models and spatially uniform) of extreme midlatitude storms under global warming. The expansion is argued to be due to the increase in the Rossby deformation radius associated with the increase in low-level dry static stability. Directions deserving future investigation in the area of climatic responses of extreme precipitation are discussed at the end of the talk.