西北地区东部一次大暴雨天气过程的诊断分析  

Diagnostic Analysis on a Rainstorm in the Eastern Part of Northwest China

作　　者：王伏村 许东蓓[2] 张德玉 代德彬 韩树浦 修韶宇 

机构地区：[1]甘肃省张掖市气象局,甘肃张掖734000 [2]兰州中心气象台,甘肃兰州730020

出　　处：《干旱区研究》2014年第3期452-462,共11页Arid Zone Research

基　　金：中国气象局关键技术集成与应用项目(CMAGJ2014M54);甘肃省气象局气象科研项目(2013-10)资助

摘　　要：使用探空、地面加密自动气象站、卫星云图、NCEP 1°×1°再分析资料,对2010年7月23日发生在西北地区东部的大暴雨过程进行了诊断分析,结果表明:低涡切变线在中、低层形成强辐合,对流层高层南亚高压东侧北风急流出口区左侧形成强辐散,高、低空系统耦合,在暴雨区上空形成强大的上升运动。在台风灿都和副热带高压作用下,副热带高压西侧偏南风低空急流源源不断向西北地区东部输送水汽。暴雨期间,整层大气可降水量与暴雨不同阶段的雨强变化一致,暴雨最强时段大气可降水量达到50 mm以上。南风风速中心向对流层中高层的加强抬升伴随暴雨增幅,降低伴随暴雨减弱。非地转湿Q矢量散度激发的次级环流强弱能反应暴雨增幅及减弱变化,低层非地转湿Q矢量散度辐合区与同时刻暴雨的强度及落区演变基本一致。中低层湿螺旋度负值区分布与相应时刻的强降水落区分布较一致,雨强中心与湿螺旋度负值中心配合较好,对降水强度和落区预报具有很好的指示性。In this study, a diagnostic analysis on a rainstorm occurred in the eastern part of northwest China on July 23, 2010 was carried out using the data from the sounding, a ground encryption automatic meteorological station, the satellite cloud images and reanalyzed data of NCEP 1 °×1°. The results showed that a strong convergence formed at mid-low level of the low vortex shear line, a strong divergence formed on the left of north jet on the eastern side of South Asia High in the upper troposphere, and an ascend movement formed over the rainstorm area in the eastern part of northwest China. Water vapor was continuously transported to the eastern part of northwest China under the interaction of the ＂Chanthu＂ typhoon and the subtropical high. During the rainstorm, precipitable water and rainfall intensity was consistent, and the precipitable water was over 50 mm during the period of strongest rain- storm. With the ascending and strengthening of southerly wind center, the rainstorm was enhanced, contrarily, it was weakened. The variation of the strength of secondary circulation excitated by divergence of non-geostrophic moisture Q-vector was in accordance with rainstorm intensity. The distribution of negative moisture helicity in midlow troposphere could give a good indicator to the distribution and center of rainfall.

关 键 词：暴雨 低涡 大气可降水量 非地转湿Q矢量 湿螺旋度 西北地区 

分 类 号：P458.121.1[天文地球—大气科学及气象学]