西北地区东部两次典型大暴雨个例对比分析  

Comparative Analysis of Characteristics of Two Typical Rainstorm Cases in the East of Northwest China

作　　者：梁生俊[1] 马晓华[1] 

机构地区：[1]陕西省气象台,西安710015

出　　处：《气象》2012年第7期804-813,共10页Meteorological Monthly

基　　金：国家自然科学基金(40975087)资助

摘　　要：利用常规高空地面资料、陕西省自动站逐时降水资料及NCEP1°×1°再分析资料,分别对2010年7月23—24日("0723")和2011年7月28—29日("0728")两次暴雨过程做了对比分析。结果表明:相对稳定的环流形势是两次大暴雨发生发展的有利背景;"0723"大暴雨发生前期低空急流就已建立,"0728"过程中伴随低空急流的形成,高空急流增强转竖,强降水发生;"0723"大暴雨期间热带低压"灿都"东侧偏南气流沿副高外围形成了一条宽而强的水汽输送通道,将南海大量的水汽和能量直接输送到陕西,"0728"大暴雨期间热带风暴"洛坦"北部的偏东南气流沿副高外围与孟加拉湾的西南气流合并后经华南、华中输送至暴雨区上空;两次过程期间陕西省均应于θ_(sc)高值区;两次过程均有干冷空气入侵、位涡扰动沿θ_(se)密集区下滑的现象。位涡随时间的变化与强降水随时间的变化几乎保持一致,化涡大值的出现预示着强降水的发生。The conventional surface and upperair sounding meteorological data, the hourly precipitation data from AWS in Shaanxi Province and the NCEP I°X 1° reanalysis data were used to analyze two rain storm processes respectively in 2324 July 2010 （＂0723＂） and 2829 July 2011 （＂0728＂）. The results show that： the relatively stable circulation is the favorable background to the development of two major rainstorms, the lowlevel jet has established at early period of the ＂0723＂ precipitation. For the ＂0728＂ rainstorm, jet stream was from east to west at its early period; accompanied with the formation of lowlev el jet, the highlevel jet stream enhances and turns upright, then heavy precipitation occurred. The south erly flow in the east of tropical depression ＂Chanthu＂ formed a wide and strong water vapor transport channel along the periphery of the subtropical high, however, the southeast airflow in the north of tropical storm ＂Nockten＂ merged with the southwest airflow from the Bay of Bengal and then transported to the rainstorm area during the ＂0728＂ rainstorm. Shaanxi Province is located in highenergy areas of during the two rainstorm processes. There are invasions of the dry and cold air, and potential vorticity disturb ance declines along the intensive areas of θin the two processes of rainstorm. Temporal changes in poten tial vorticity and precipitation almost take place simultaneously, and the appearance of large values of po tential vorticity indicates the occurrence of rainstorm.

关 键 词：大暴雨 环流背景 高低空急流 台风 干侵入 

分 类 号：P458.121.1[天文地球—大气科学及气象学]