STUDY OF DOUBLE RAIN BANDS IN A PERSISTENT RAINSTORM OVER SOUTH CHINA  

作　　者：丁治英 刘彩虹 常越 沈新勇 何金海 徐海明 

机构地区：[1]Jiangsu Key Laboratory of Meteorological Disasters, Nanjing University of Information Science & Technology (NUIST) [2]College of Atmospheric Sciences, NUIST [3]Guangzhou Municipal Meteorological Center

出　　处：《Journal of Tropical Meteorology》2010年第4期380-389,共10页热带气象学报（英文版）

基　　金：National Program on Basic Research Project (973 Program) (2009CB421503);Natural Science Foundation of China (40975037);Natural Science Foundation of China (40775033)

摘　　要：Using the U.S. National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis data at 1°× 1° o resolution, analysis is performed on a persistent heavy rainfall event with two rain bands to the south of the Yangtze River during 17-22 June 2005. The northern rain band was related to the atmospheric mass adjustment of cold front precipitation and the associated ageostrophic feature to the rear right of subtropical westerly jets, while the southern counterpart formed under the joint influence of easterly/westerly jets and the South Asian high （SAH）. The ageostrophic wind field to the rear right of the easterly jet center gives rise to an anti-circulation that favors the genesis of the southern belt. The feature ofdu/dt 〈0 around the SAH ridge line and to the rear right of the easterly jet streak results in a strong v - vg〈O field in the vicinity of the rain region as well as to its south. When westerly jets move southward, an intense v Vg〉0 feature appears to the north of the rain region, i.e., behind the center of the westerly jets. The associated mass adjustment leads to vigorous divergence over the rain region, which is responsible for the strong precipitation from the warm sector of the front. Also, a θe front at the middle level of the southern rain band and the cold front favor the release of instable energy to enhance the rainstorm. The southern and northern fronts approach each other and the two rain belts merge into one.Using the U.S. National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis data at 1°×1° resolution, analysis is performed on a persistent heavy rainfall event with two rain bands to the south of the Yangtze River during 17–22 June 2005. The northern rain band was related to the atmospheric mass adjustment of cold front precipitation and the associated ageostrophic feature to the rear right of subtropical westerly jets, while the southern counterpart formed under the joint influence of easterly/westerly jets and the South Asian high (SAH). The ageostrophic wind field to the rear right of the easterly jet center gives rise to an anti-circulation that favors the genesis of the southern belt. The feature of du/dt <0 around the SAH ridge line and to the rear right of the easterly jet streak results in a strong v – vg<0 field in the vicinity of the rain region as well as to its south. When westerly jets move southward, an intense v – vg>0 feature appears to the north of the rain region, i.e., behind the center of the westerly jets. The associated mass adjustment leads to vigorous divergence over the rain region, which is responsible for the strong precipitation from the warm sector of the front. Also, a θe front at the middle level of the southern rain band and the cold front favor the release of instable energy to enhance the rainstorm. The southern and northern fronts approach each other and the two rain belts merge into one.

关 键 词：easterly/westerly upper-air jets warm-region rainstorm middle-level front mass adjustment 

分 类 号：P426.62[天文地球—大气科学及气象学]