北京与兰州地区的地闪特征

THE CHARACTERISTICS OF GROUND FLASHES IN BEIJING AND LANZHOU REGIONS

利用闪电定位系统(LLS)在兰州地区和北京地区探测到的共两万多个地闪资料,对两地的正、负地闪特征进行了对比。分析发现兰州地区的正闪比例是北京地区正闪比例的5倍多。北京地区的正闪平均强度近似为负闪的3倍,而兰州地区的正闪强度只有负闪的2.2倍。无论正闪还是负闪,两地的地闪强度均是稳定的正态分布,并且与雷暴本身的特征无关,从而可用DF强度来作雷暴临近的估计。两地的正、负地闪的回击数均按指数规律下降,不过北京地区的多次回击较兰州地区的多次回击要多。两地的闪电频数都在下午后期出现峰值,但北京地区的闪电频数最大值和最小值都较兰州地区早1小时出现。 通过试验找到了地闪定向仪显示数与闪电辐射电场和放电电流的关系,扩大了地闪定向仪的利用率。

Over twenty thousand lightning location data from Lanzhou region and Beijing area have been analysed.The ratio of positive flashes and total ground flashes is 5 times higher in Lanzhou than in Beijing. The strength of positive flashes is 3 times and 2.2 times as large as negtive flashes in Beijing and in Lanzhou, respectively.The peak flash rate oc-cured in late afternoon for both area, but the maximum and minimum flash rate appeared one hour earlier in Beijing than in Lanzhou. The relationship between DF display and lightning radiation electric field and discharge current is obtained.