山东人工引发雷电综合观测实验及回击电流特征

山东人工引发雷电实验 （SHATLE) 自2005年开始, 六年来共成功引发负极性雷电22次, 包含大电流回击过程88次, 实验获取了包括雷电放电通道底部电流、近距离电磁场、 高速摄像等在内的高质量同步观测资料。对36次实测回击电流的统计分析表明, 回击峰值电流的几何平均值为12.1 kA, 最大值为41.6 kA, 最小值为4.4 kA。回击电流波形的半峰值宽度范围在1～68 μs之间, 电流10%～90%峰值的上升时间几何平均值为1.9 μs, 中和电荷量为0.86 C, 作用积分（action integral, 或称比能量) 为2.6 ×103A2?s。人工触发闪电峰值电流约16.5 kA的回击在30 m处产生的电场变化可达56.0 kV/m, 60 m处的磁场几何平均值为52 μT。一些强烈的M分量可以具有与回击相当的电流峰值和中和电荷量。人工引雷初始阶段上行正先导的发展速度约为0.96×105 m/s。

Shandong Artificially Triggering Lightning Experiment and Current Characterization of Return Stroke

Shandong Artificially Triggering Lightning Experiment (SHATLE) has been conducted continuously since the summer of 2005. During the six years from 2005 to 2010, twenty-two negative lightning flashes containing eighty-eight return strokes were successfully triggered. Channel base currents, close electromagnetic fields, and high-speed camera images were obtained simultaneously for some of the strokes. Based on directly measured currents for thirty-six return strokes, the geometric mean of return stroke peak current was about 12.1 kA with a maximum of 41.6 kA and a minimum of 4.4 kA, the half peak width of current varied from 1 to 68 μs, and the geometric mean values of 10%-90% risetime, charge transfer, and action integral were about 1.9 μs, 0.86 C, and 2.6×103A2·s, respectively. The surface electric field at 30 m away from the discharge channel caused by a return stroke with peak current of 16.5 kA reached 111.9 kV/m. The geometric mean of magnetic field at 60 m away from the discharge channel was about 52 μT. The peak current and charge transfer of some large M components were comparable with those of return stroke. The speed of upward positive leaders in the initial stage of triggered flashes was about 0.96×105 m/s.