Boundary Layer Recovery and Precipitation Symmetrization Preceding Rapid Intensification of Tropical Cyclones under Shear

Abstract This study investigates the precipitation symmetrization preceding rapid intensification (RI) of tropical cyclones (TCs) experiencing vertical wind shear by analyzing numerical simulations Typhoon Mujigae (2015) with warm (CTL) and relatively cool (S1) sea surface temperatures (SSTs). A novel finding is that maintained continuous development deep convection along inward flank a convective shield (CPS), especially in downwind part. Beneath CPS, downdrafts flush boundary layer low-entropy parcels. These parcels do not necessarily weaken TCs; instead, they are “recycled” TC circulation, gradually recovered positive enthalpy fluxes, develop into during their propagation toward downshear convergence zone. Along-trajectory momentum budget analyses reveal predominant role buoyancy acceleration both experiments. The recovery more efficient for warmer SST, stronger accounts higher probability these developing part which helps maintain CTL. In contrast, less upshear hinder S1. findings highlight key regulating convection, further an earlier RI onset timing CTL TC. inward-rebuilding pathway also illuminates why preferentially located inside radius maximum sheared TCs undergoing RI.