吉林省一场持续性暴雨成因及MCC特征分析  

Analysis on Causes and MCC Characteristics of a Continual Heavy Rain Process in Jilin Province

作　　者：王宁[1] 王秀娟[1] 张硕[1] 云天[1] 冯旭[1] 

机构地区：[1]吉林省气象台,长春130062

出　　处：《气象》2016年第7期809-818,共10页Meteorological Monthly

基　　金：中国气象局预报员专项(CMAYBY2014-015)资助

摘　　要：利用常规气象观测资料、区域自动站降水资料、NCEP 1°×1°逐6 h再分析资料及FY-2E卫星云图资料,对2013年8月14—17日吉林省持续性暴雨过程环流形势演变特征、暴雨成因及其中尺度特征进行了诊断分析。结果表明:在异常稳定的大尺度环流背景下,中纬度锋区上先后有两次高空槽沿同一路径东移、重复影响吉林是造成持续性暴雨的重要原因。降水过程分为两个集中阶段,第一阶段以对流性强降水为主,θ_(se)锋区随高度向南倾斜,具有条件不稳定并且水汽充沛,形成较大的对流有效位能;而第二阶段逐渐转为混合性强降水,θ_(se)锋区随高度向北倾斜,在水汽输送强度、降水时间及降水总量等方面均明显强于第一阶段。强降水发生期间,先后形成α中尺度对流云团或MCC,分3个阶段影响吉林省,在云团发展阶段,具有低层气旋式涡度伴随中尺度辐合,高层反气旋涡度伴随中尺度辐散的垂直结构,且上升速度明显,同时925 hPa超低空急流前端风速辐合的反复出现亦是暴雨持续发生可能的中尺度触发机制。Using conventional meteorological data, regional automatic station precipitation data, NCEP 1°×1° reanalysis data and FY-2E satellite cloud image, evolution characteristics of the circulation situation, causes of the rainstorm and mesoscale features of the continual torrential rain process in Jilin Province from 14 to 17 in August 2013 were analyzed. The results show that in the unusually stable large-scale circulation background, the torrential rain was mainly caused by two upper troughs which moved to the east along the same path on the middle latitude frontal zone and repeated impacting Jilin Province. The precipitation process was divided into two major stages. In the first stage, it was severe convective precipitation. 0.~e frontal zone tilted to the south along height unstably and water vapor was abundant, forming large convec- tive available potential energy. In the second stage, however, the rainfall gradually turned to mixed severe precipitation. θse frontal zone tilted to the north with height, the intensity of water vapor transport, pre-cipitation duration and total rainfall amount were significantly stronger than in the first stage. During heavy rainfall, θse mesoscale convective cloud cluster or MCC was formed successively and divided into 3 stages, impacting Jilin. In the developing stage of cloud cluster, there was a vertical structure of cyclonic vorticity with the mesoscale convergence on low altitude, anticyclone vorticity with the mesoscate divergence on high altitude, and the rising velocity was obvious. At the same time, the recurring of the wind speed convergence which was in the front of a ultra-low-level jet at 925 hPa was also the possible mesoscale triggering mechanism of the continual heavy rain.

关 键 词：持续性暴雨 水汽输送 θsc锋区 热动力条件 MCC垂直结构 

分 类 号：P458[天文地球—大气科学及气象学]