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- Title
Microphysics of Heavy Rain Associated With the Eyewall and Inner Rainbands of Typhoon Meranti (2016).
- Authors
Wang, Lan; Bao, Xuwei; Hu, Yajun; Zhang, Shuai; Lin, Wen; Zhuang, Yao
- Abstract
Heavy rain in a tropical cyclone (TC) tends to occur in its eyewall and inner spiral rainbands. The distinct dynamical and thermodynamical structures between TC eyewall and inner rainbands were argued to be responsible for different rain microphysics by previous studies. Thus, this study investigated the microphysical characteristics of heavy rain (≥10 mm hr−1) associated with the eyewall and inner rainbands of Typhoon Meranti (2016), based on the joint observations of two disdrometers and a dual‐polarization radar (DPR) as well as automatic weather stations in Fujian province of China. The surface disdrometer observation showed that the eyewall rain has a larger mean raindrop diameter and a smaller mean concentration than the inner‐rainband rain. In general agreement with the disdrometer observation, the DPR observation confirmed larger sizes of raindrops near the ground in the eyewall. However, the vertical profiles of polarimetric variables showed larger values almost throughout the atmosphere in the eyewall, namely that more efficient ice‐ and warm‐cloud processes are evident for the production of ice and rain particles. This result looks contradictory to the lower concentration of the eyewall rain than the inner‐rainband rain as measured by surface disdrometers. This is because stronger updrafts observed in the eyewall not only facilitate the production and growth of hydrometeors, but also prevent small raindrops from falling to the ground. Consequently, the surface rain in the eyewall has larger raindrop diameter and lower concentration than that in the inner rainbands, despite a larger number of ice and rain particles in the atmosphere. Plain Language Summary: The accurate quantitative precipitation forecast of tropical cyclones (TCs) remains challenging, even associated with various rainbands of a TC. Previous studies argued that different dynamically formation mechanisms are responsible for the difference of cloud structures between TC eyewall and rainbands, causing the variation in their surface rain rates. However, it is not clear whether there is also difference in microphysical processes between TC eyewall and rainbands, and what role microphysical processes play in the rain rate. This study tends to answer these questions using the joint observations of surface disdrometers and dual‐polarization radar. Consequently, different drop size distributions of surface rain and vertical profiles of polarimetric radar variables were presented in the eyewall and inner rainbands of Typhoon Meranti (2016) at the same surface rain rate. Favorable dynamical conditions (e.g., stronger updrafts) in the eyewall were discussed to elucidate more efficient ice‐ and warm‐cloud processes for the production of ice and rain particles, indicated by larger values of polarimetric variables in the vertical. However, stronger updrafts can also prevent small raindrops from falling to the ground, leading to larger raindrop diameter and lower concentration of surface rain in the eyewall than in the inner rainbands at the same rain rate. Key Points: More efficient ice‐ and warm‐cloud microphysical processes were found in tropical cyclone (TC) eyewall than in inner rainbandsMore ice and rain particles appear to be produced in TC eyewall, but not all raindrops can fall to the groundUnique dynamics (e.g., stronger updrafts) in TC eyewall are responsible for the microphysical difference with the inner‐rainband rain
- Subjects
FUJIAN Sheng (China); CHINA; RAINFALL; TROPICAL cyclones; ICE clouds; DROP size distribution; RAINDROP size; AUTOMATIC meteorological stations; MICROPHYSICS
- Publication
Journal of Geophysical Research. Atmospheres, 2023, Vol 128, Issue 22, p1
- ISSN
2169-897X
- Publication type
Article
- DOI
10.1029/2022JD037288