周玉淑,邓国,黄仪虹. 2003. 长江流域一次暴雨过程中的不稳定条件分析[J]. 气象学报, 61(3):323-333, doi:10.11676/qxxb2003.031
长江流域一次暴雨过程中的不稳定条件分析
ANALYSIS ON INSTABILITY CONDITION DURING A TORRENTIAL RAIN OVER YANGZI RIVER BASIN
投稿时间:2002-06-06  修订日期:2002-12-20
DOI:10.11676/qxxb2003.031
中文关键词:  暴雨  对流不稳定  对称不稳定  涡层不稳定
英文关键词:Torrential rain  Convective instability  Symmetry instability  Vortex sheet instability
基金项目:中国科学院知识创新工程项目(KZCX3SW213);中国科学院KZCX2208项目
作者单位
周玉淑 中国科学院大气物理研究所, 北京, 100029 
邓国 国家气象中心, 北京, 100081 
黄仪虹 广东省汕头市气象局, 汕头, 515041 
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中文摘要:
      文中分析了1998年7月20~23日发生于长江流域的持续性降水和暴雨过程,在分析大尺度降水和中小尺度暴雨相对应的环流场和天气实况的基础上,主要分析相应大气层结的对流不稳定和条件性对称不稳定条件,并对切变线上涡层不稳定做了重点介绍和分析,计算了条件性对称不稳定判据和涡层不稳定判据。结果表明:降水期间大气低层有对流不稳定和对称不稳定能量的积聚,在这两类不稳定条件都基本满足的情况下,涡层不稳定的维持对此次降水过程中暴雨的发生提供了有利的不稳定环境场,具体的计算分析还表明环境场的配置制约着切变线上低涡扰动的发展,是造成降水的重要原因之一。
英文摘要:
      In this paper, the torrential rain occurring over Yangtze River Basin in 20-23July 1998 is analyzed. Based on circulation and weather events corresponding to large-scale precipitation and meso-microscale torrential rain, convective instability and conditional symmetry instability in atmosphere are analyzed, the criteria of symmetry instability as well as vortex sheet instability are colculated and analyzed. Analyses of the convective instability and conditional symmetry instability indicate that the convective instability provides instable energy for the torrential rain, and energy of conditional symmetry instability also accumulates at 925-1000 hPa during the rainfalls. Because the criterion of the conditional symmetry instability is not satisfied above 700 hPa for all rainfall regions, it is not enough to explain the formation of the torrential rain if the conditional symmetry instability it self is considered. The torrential rain did not always occur in the areas where the criterion of convective instability and conditional symmetry instability are satisfied. On the condition of convective inst ability and conditional symmetry instability, it is easy to explain the torrential rain over Yangtze River Basin with the theory of vortex sheet instability. Calculation of the prerequisite of vortex sheet instability also indicates that vortex sheet instability is an important factor contributing to the torrential rain over the Yangtze River Basin in 20-23 July 1998.
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