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安徽地区一次致灾雷暴过程的闪电特征分析

Analysis of lightning characteristics during a disaster-causing thunderstorm in Anhui Province

  • 摘要: 利用常规气象观测资料、ERA-Interim 0.5°×0.5°再分析资料、Himawari-8气象卫星数据、安庆多普勒天气雷达资料和安徽省ADTD闪电定位系统数据,对2017年8月19日安徽中部地区一次雷暴天气过程的大气环流背景和闪电特征进行了分析,并针对这次雷暴天气过程中发生的一次雷电灾害进行了细致分析。结果表明:(1)此次雷暴天气过程发生在500hPa副热带高压北部边缘及高空前倾槽前,对流层中低层黄淮气旋切变、低空急流及中尺度地面辐合线为这次过程的重要影响系统,强对流天气发生在大气不稳定层结条件下。(2)雷暴过程生命周期约为4 h,影响范围覆盖合肥及周边地区。雷暴过程以负地闪为主,正负地闪比例为1:25。(3)负地闪集中发生在雷暴的成熟期,正地闪在成熟和消散期出现较多。78.2%的地闪集中发生在40~55 dBz的雷达强回波区,正负地闪的位置分布差异较大,在雷暴成熟期负地闪集中区域与强回波中心区域较为吻合,而正地闪多分布于强回波边缘和弱回波区。(4)此次雷电灾害发生在MCS南侧边缘,由一个新生发展的γ中尺度对流单体所致,灾害发生在该单体的成熟阶段。灾害附近区域地闪密度约为1次·km-2,雷电灾害主要因人员躲避不及所致,这表明雷电灾害的发生不仅与致灾因子(雷电)有关,还与承灾体的暴露度、脆弱性和雷电防护水平有关。

     

    Abstract: Atmospheric circulation and lightning characteristics during a disaster-causing thunderstorm occurred in Anhui province on August 19, 2017 were analyzed by using data from meteorological stations, ERA-Interim 0.5°×0.5° reanalysis, Himawari-8, Doppler radar in Anqing and ADTD lightning location system in Anhui province. Careful analysis of lightning disaster during the thunderstorm was made specially. The results show that (1) the thunderstorm occurred near the northern edge of subtropical high ridge and front of forward-tilted trough. Huang-Huai cyclonic shear at mid-low troposphere, low level jet and mesoscale surface convergence line are main affecting systems for the thunderstorm. And severe convection occurs under the condition of unstable atmospheric stratification. (2) The thunderstorm lasted about 4h, which covers Hefei and its neighboring areas and negative cloud-ground lightning is dominant during the thunderstorm. The ratio of positive and negative cloud-ground lightning is 1:25. (3)Most negative cloud-ground lightning occurred during the mature period of thunderstorm, and the positive cloud-ground lightning occurred frequently during the mature and dissipation period of thunderstorm. The percentage of cloud-ground lightning occurred in the echo region of 40-55 dBz is 78.2%. There is significant difference of distribution between positive and negative cloud-ground lightning. The concentrated areas of negative cloud-ground lightning are consistent with the strong echo area, while positive cloud-ground lightning are mostly distributed on the edge of the strong echo and weak echo area. (4)The lightning disaster is caused by a γ mesoscale convective cell at southern edge of the thunderstorm. The lightning disaster occurred in the mature segment of the cell. Lightning density around the disaster is 1 times·km-2. Reason for the disaster is mainly due to not having enough time for people to avoid being hurt from lighting. It indicates that lightning disasters are not only related to the disaster factors as lightning, but the exposure, vulnerability degree and lightning protection level of the disaster body are also important factors for lightning disaster.

     

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