Microphysical characteristics of the phase-locking VRW-induced asymmetric convection in the outer eyewall of Super Typhoon Lekima (2019)

Microphysical signatures relevant to the asymmetric convection in the outer eyewall of Super Typhoon Lekima (2019) before its landfall in China were analyzed from ground-based radar observations. The results indicate that the microphysical characteristics varied in quadrants. In the upshear-left outer eyewall, the convection was deepened on the inner edge due to the phase locking between vortex Rossby waves (VRWs), and warm rain was the predominant process contributing to the enhancement of rainfall. In contrast, the strongest precipitation occurred on the outer edge of the upshear-right outer eyewall. In this region, exuberant riming processes and graupel formation prevailed above the melting layer due to the strongest and more outward tilted updrafts induced by the phase locking between the VRWs. A good deal of graupel melted into raindrops, along with significant accretion processes, produced intense rainfall with larger drop sizes.