Comparative Analysis of Precipitation Distributions of Tropical Cyclones Making Landfall in East China
Received:June 22, 2018  
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KeyWord:Tropical cyclones  Landfalling East China  Precipitation  Different distributions
Author NameAffiliationE-mail
卜松 中国气象科学研究院灾害天气国家重点实验室  
李英 中国气象科学研究院灾害天气国家重点实验室 yli@cma.gov.cn 
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Abstract:
      In this paper, the atmospheric circulation field, vertical shear of ambient horizontal wind, and dynamical and thermal conditions within the typhoon circulations of East China-landfalling tropical cyclones (TC) for the period 2005-2014 were compared and analyzed. Using CMORPH precipitation data, the TC precipitation was classified into two categories: left side of track (L) and right side of track (R). Results showed that the 20 landfalling TCs included twelve L TCs and eight R TCs. In general, atmospheric circulation factors played a major role in the TC precipitation distributions. During landfall of the L TCs, in the upper troposphere, the South Asian high was zonally distributed and the flow was divergent on the left side of the track area, a westerly trough featured to the east mid-troposphere, and the western Pacific subtropical high was located to the south, with a southwesterly vertical speed shear of the ambient horizontal wind. In contrast, for the R TCs, the South Asian high was longitudinally oriented in the upper troposphere, then broke down. On the left side of track, wind was relatively uniform, except for a strong divergent flow on the right. The subtropical high was much further north and was blocking, and the vertical shear of the ambient horizontal wind was northeast, which was conducive to R-type precipitation. Thermal advection and water vapor convergence within the typhoon circulation corresponded well with the rainfall area. Warm advection occurred in the lower layers of the southwest quadrants of the L TCs, leading to decreasing atmospheric stability. At the same time, the water vapor convergent zone was also located in the southwest quadrant, contributing to precipitation on the left side of the TC track. For R TCs, the subtropical high was further north and transported warm, moist air on southeasterly flow to the west of the typhoon, and the northeastern quadrant always maintained warm advection, which was favorable for rainfall on the right side of the track.