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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 overYangtze-Huaihe basin in summer

  • 摘要: 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。

     

    Abstract: 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(MβCCS) and meso-β elongated convective system (MβECS) 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 MβECS occur more frequently than MCC and MβCCS, 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 MCSs 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 themain distance is 1~5 latitude and longitude degrees, accounting for 64.6%.

     

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