河西走廊中西部干旱区极端暴雨个例分析  

Case Analysis of Extreme Rainstorm in Arid Zone of the Midwestern Gansu Corridor

作　　者：孔祥伟[1] 陶健红[2] 刘治国[2] 傅朝[1] 吉惠敏[1] 

机构地区：[1]兰州中心气象台,兰州730020 [2]甘肃省气象局,兰州730020

出　　处：《高原气象》2015年第1期70-81,共12页Plateau Meteorology

基　　金：中国气象局气象关键技术集成与应用重点项目(CMAGJ2013Z09);公益性行业(气象)科研专项(GYHY201206029;GYHY201306006)

摘　　要：利用常规、自动气象观测站资料、卫星资料及NCEP 1°×1°再分析资料,对2012年6月4 5日河西走廊中西部干旱区极端暴雨天气过程的影响系统配置、中尺度特征、水汽输送、不稳定能量等方面进行了诊断分析。结果表明:此次暴雨发生在地面冷锋过境后,降温冷凝作用明显,对流层高层存在强抽吸作用,中层高原低涡受其下游弱脊阻挡较长时间维持在暴雨区上空,低层存在切变线,高低空系统的耦合提供了中尺度对流系统发生、发展的有利条件;水汽主要来自对流层中低层东、西两路及高层南路三支水汽输送通道,西路水汽输送强度最大,东路水汽输送受小高压影响显著,暴雨开始后6 h才完整建立,暴雨中心整层大气可降水量达到了该地区夏季平均值的两倍多;通过降温、增湿作用近地面出现对流不稳定能量,自由对流高度较低;涡旋云系的冷空气侵入处,不断激发出6个β中尺度的对流单体,暴雨中心玉门两次受其中4个单体的影响,产生短时强降水。An extreme rainstorm has occurred in the midw estern of Gansu Corridor arid zone on 4 5 June2012. Using the data of conventional and automatic weather stations,FY- 2D satellite cloud image as w ell as NCEP 1° × 1° reanalysis data,the impacts of influence system configuration,meso-scale characteristics,w ater vapor transport and unstable energy have been analyzed. The main results are as follow s. After the ground cold front had passed,rainstorm happened,cooling condensation effect w as significant. No convergence system formed on ground,w hile strong suction existed in upper troposphere; plateau low vortex w hich w as blocked by its dow nstream w eak ridge stayed longer over the rainstorm area in middle troposphere; a shear line could be found in low troposphere,the configuration of the upper and low influence systems provided meso-scale convection conditions. Water vapor came from east and w est in the low troposphere and south in the upper troposphere,the w est vapor transport w as strongest,and east vapor transport w as affected significantly by high pressure. The w hole precipitation w ater w as tw ice more than the climate. Cooling and humidifying in the boundary layer forced the convective energy to be unstable,and free convection altitudes w as low,without the need of strong uplift triggering mechanism. The six meso-β-scale convection cells had been activated at the cold air intrusion of low vortex cloud,and Yumen station w hich w as affected by four convection cells w as divided into tw o periods to produce short-time severe precipitation.

关 键 词：河西走廊中西部 极端暴雨 高原低涡 

分 类 号：P458.121.1[天文地球—大气科学及气象学]