A Comparison of Convective Raindrop Size Distributions in the Eyewall and Spiral Rainbands of Typhoon Lekima (2019)
Xuwei Bao, Liguang Wu, Shuai Zhang, Huizhen Yuan, Huihui Wang
Abstract
Abstract A reliable shape–slope ( μ‐Λ ) relationship for polarimetric retrieval in tropical cyclones (TCs) is unavailable due to the lack of raindrop size distribution (RSD) measurements within the TC eyewall. This study presents an analysis of the convective RSDs in the eyewall and spiral rainbands, based on ~26 hr of measurement from 17 Thies disdrometers during the landfall of Typhoon Lekima (2019) in eastern China. A μ‐Λ relationship for polarimetric retrieval in the eyewall is derived, which is different from those in spiral rainbands of Lekima. The average raindrop diameter parameter D m (concentration parameter log 10 N w ) is found to generally decrease (increase) radially from the TC center, but note that most rain samples with intense rain rate >50 mm hr −1 occur in the convection‐dominated portion of inner rainbands. To explain why, an equilibrium RSD is proposed as a constraint on the growth of D m and log 10 N w with increasing rain rate.