夏季江淮地区中尺度对流系统的统计特征分析

Statistical analysis of mesoscale convective systems over Yangtze-Huaihe basin in summer

利用2007—2013年6—8月FY-2D逐小时相当黑体温度（TBB）资料,普查了夏季我国江淮地区的中尺度对流系统（MCS）个例。根据MCS的组织形式将其分为中尺度对流复合体（MCC）、持续拉伸状对流系统（PECS）、β尺度中尺度对流复合体（MβCCS）和β尺度持续拉伸状对流系统（MβECS）,并对各组织形式MCS的统计特征做了对比分析。结果表明：夏季江淮地区带状MCS发生的频次明显高于圆状MCS,占62.2%;7月份MCS个例数最多,而6月份MCS成熟时平均面积最大;整个夏季,MCS成熟时平均最低云顶温度约为-76℃;MCS多形成于午后14—17时,成熟于17—19时,18—23时均为MCS易消散时段,具体到各类型,其日变化特征又有所差异;影响江淮地区的MCS多生成在陆地上,海上个例很少,有向东、东北和东南3个主要移向,共占73.1%,移动1～5个经纬距的MCS所占比例最大,为64.6%,MCS的移动距离与其生命史长度密切相关。

The mesoscale convective systems（MCSs） over Yangtze-Huaihe basin were classified into mesoscale convective complex（MCC）, persistent elongated convective system（PECS）, meso-β circular convective system（M β CCS） and meso-β elongated convective system （M β ECS） based on the FY-2D geostationary satellite blackbody temperature data during June to August from 2007-2013. The statistical characteristics of different kinds of MCS cases were analysed. The results indicate that PECS and M [3 ECS occur more frequently than MCC and M β CCS, accounting for 62.2%. There are most MCSs in July while the mean area of mature MCSs in June ranks first, and the average minimum blackbody temperature of mature MCSs is about -76℃. The peak time for MCS initiation is around 14：00-17：00 BT while most MC- Ss mature in the period of 17：00-19：00 BT and dissipate during 18：00-23：00BT, however, it differs for diverse types. Most MCS cases which influence Yangtze-Huaihe basin generate in the land while rarely in the sea. Eastward, northeastward and southeastward are the three main moving directions for MCSs, with a total percentage of about 73.1%. The moving distance of MCS case is closely related to its lifetime and the main distance is 1-5 latitude and longitude degrees, accounting for 64.6%.