“0811”暴雨过程中MCC与一般暴雨云团的对比分析

利用T639 1°×1°分析场、FY-2红外云图、红外辐射亮温(TBB)、闪电定位和气柱水汽总量等资料,对2010年8月11日发生在山西南部暴雨过程(即"0811"暴雨过程)中的中尺度对流复合体(MCC)和其北部的一般暴雨云团进行了对比分析,结果表明,(1)山西北部暴雨带主要由6个β中尺度对流云团生成、发展及合并造成;山西南部区域性暴雨则由MCC的生成、发展、东移所引发。(2)山西北部的暴雨云团在850hPa暖切变线南部生成和发展,并在地面切变线附近合并;山西南部的MCC由3个β中尺度对流云团发生、发展及合并形成,该对流云团在700hPa次天气尺度切变线上触发生成;MCC发展、成熟阶段,α中尺度云团沿925hPa暖切变线东移;减弱阶段,随西太平洋副热带高压的南退而南压。(3)在西太平洋副热带高压西进北抬的背景下,同一次暴雨过程中,MCC发生在5 880gpm边缘弱的斜压环境中,高层则出现在高压北侧的反气旋环流中;一般暴雨云团发生在5 840gpm边缘较强的斜压环境中,高层则出现在急流入口区的右侧。(4)MCC作为大型的中尺度对流系统,不但对低层高温高湿能量的需求比一般暴雨云团更多,而且在垂直方向上,要求湿层、高能舌及暖温结构更深厚。(5)山西南部MCC影响区和5 880gpm线边缘为负地闪覆盖区,正地闪主要出现在其北部一般暴雨云团影响区和5 840gpm线附近。与MCC相比,一般暴雨云团影响下,局地闪电开始及闪电峰值的出现较降水的开始及降水峰值的出现有更多的提前量。(6)山西北部暴雨云团出现在气柱水汽总量梯度的大值区及水汽锋上;山西南部MCC则出现在水汽锋南侧气柱水汽总量的大值区。气柱水汽总量对"0811"暴雨过程有36h的提前量,对暴雨的落区有很好的指示意义。

Comparative Analysis on MCC and Cloud Clusters of General Rainstorm during ’0811’ Rainstorm Process

The mesoscale convective complex(MCC) in the south of Shanxi and the rainstorm cloud clusters in the north of Shanxi on August 11,2010 are comparatively analyzed by using T639 1°×1° reanalysis data,FY-2 infrared satellite image and infrared black body temperature(TBB) data,lightning data and total column water vapor data.Itdemonstrate that rainstorm area in the north of Shanxi was causedby the generation,development,merger of 6 meso-β-scale convective cloud clusters,and the south regional rainstorm happened with the generation,development and eastward movement of the mesoscale convective complex(MCC).The analyzed results indicate that:(1) The northern rainstromcloud cluster developedin the south of warm shear line on 850 hPa,and mergednear by shear lineon surface.At the same time,the southern MCC was merged by 3 meso-β-scale convective cloud clusters,which developed on the weather-scale shear lineon 700 hPa.In the process of MCC development and maturity stage,meso-α-scale convective cloud clusters moved east along the warm shear lineon 925 hPa,and intheprocess of MCC weakening,meso-α-scale convective cloud clusters moved south with the southward movementof subtropical high belt.(2) With the northwestward advance of the subtropical high during thesame rainstorm,MCC developed in the weak baroclinic environment of the 5 880 gpm region,and in the anticyclone north of high onupper levels;rainstorm cloud clusters tended to develop in the strong baroclinic environment of 5 840 gpm region,and in the the right of the upper jet stream entrance area.(3) As a large scale mesoscale convective system,MCC required more energy of high temperature and high humidity than general rainstorm cloud clustersinlower levers,and deeper vertical structure of high humidity,high energy tongue and high temperature.(4) The negative cloud-to-ground lightning appeared in the area which was influenced by the southern MCC and near the 5 880 gpm region;the positive cloud-to-ground lightning appeared in the area which was influenced by the northern rainstromcloud clusters and near the 5 840 gpm region.The time of the begin of lightning and the appearanceof the lightning peak was more earlierthan the time of rainfall and the appearance of the rain intensity peak in the backgroud of general rainstorm cloud clusters,comparing with the banckground of MCC.(5) The northern rainstorm cloud clusters developed in the area of high gradient of vertically integrated water content and on the front of water vapor;the southern MCC developed in the area of high value of total column water vapor,thesouth of the water vapor front.There is ahead 36 h to exactly forecast the total column water vapor data of the rainstorm process on August 11,which showsa significant indication to rainstorm area.