一次无地面冷空气触发的西南涡特大暴雨分析  

Analysis of a Torrential Southwest Vortex Rainstorm Without Surface Cold Air Intrusion

作　　者：王中[1,2] 白莹莹[1] 杜钦[1] 李东川 

机构地区：[1]中国气象局武汉暴雨研究所,430074 [2]重庆市气象科学研究所 [3]重庆市万州区气象台

出　　处：《气象》2008年第12期63-71,共9页Meteorological Monthly

基　　金：中国气象局武汉暴雨研究所暴雨研究开放基金项目(IHR2007G03);重庆市自然科学基金项目(CSTC,2007BB9248);中国气象局成都高原气象研究所开放基金项目(LPM200814)共同资助

摘　　要：利用NCEP1°×1°的再分析资料对2007年7月17日重庆西部的特大暴雨天气过程的环流背景、主要影响系统——西南涡的演变进行诊断分析。结果表明:(1)在有利的大尺度环流背景配合下,产生此次过程的主要影响系统为西南涡和低空急流,副热带高压的西进北抬为水汽的输送提供了有利的条件;(2)最强降水时段出现在西南涡的最强盛期,垂直螺旋度的大值中心位置和强弱变化与低涡及强降雨的位置和强度有很好的对应关系;(3)在此次过程中虽然无地面冷空气的触发,但由于高层较强的冷平流形成的干冷盖和低层的暖湿气流与强烈的上升运动的极佳配合,使得强对流天气得以发生,高层的干侵入成为此次过程的触发动力;(4)西南低涡上空的不同高度上不同强度的干侵入效应,使得高层高位涡下传,而高层高位涡区的下传和中低层高位涡区的加强,导致西南低涡的气旋性环流加强,降水增强。Based on the reanalysis data with 1°×1° resolution from NCEP/NCAR, the circulation background and the main influencing systems of ＂07.17＂ torrential rainstorm in the west of Chongqing in 2007 are analyzed. The results indicate that under advantageous large-scale circulation background coordination, the main influence systems were the southwest vortex and low-level jet stream. The west Pacific subtropical high provided the advantageous condition for transportation of water vapor by its west stretch and north lift. The strong raining processes began at the peak of the development of southwest vortex. The high center and intensity of vertical helicity had a corresponding connection with the position and intensity of heavy rainfall. Although without surface cold air intrusion, in the upper troposphere the dry air intrusion provided triggering power of rainstorm. The strong convection weather was affected directly by the dry and cold lid at high level caused by strong cold advection and the warm and wet air at low level when they interacted with strong ascending. The different influences of dry intrusion at different levels over the southwest vortex made high potential vorticity in upper troposphere go down and increase in lower troposphere, which strengthened southwest vortex and the intensity of precipitation.

关 键 词：特大暴雨 西南涡 垂直螺旋度 位涡 干侵入 

分 类 号：P425.55[天文地球—大气科学及气象学] P458.121.1