北京及其周边地区夏季地闪活动时空特征分析

SPATIAL AND TEMPORAL CHARACTERISTICS OF CLOUD-TO-GROUND LIGHTNING IN SUMMER IN BEIJING AND ITS CIRCUMJACENT REGIONS

利用M-LDARS闪电定位系统对北京及其周边地区1995～1997年6～9月的闪电观测数据,分析闪电活动的时空分布特征.结果表明:闪电活动在时间分布上存在两个峰值时段,13:00～21:00和23:00～次日05:00.通过对总地闪、分时段及峰值时段的地闪密度分析,发现北京及周边地区闪电活动有几个明显的集中区域,地闪高密度区主要出现在下垫面为山脉和水体的地方,闪电活动与下垫面的水汽条件关系密切,且正、负地闪的空间分布也呈现较大差异,表明雷暴云的电荷结构存在一定差异.

In terms of the observations from M-LDARS single station lightning location system, the spatial and temporal characteristics of cloud-to-ground （CG） lightning activities in Beijing and its circumjacent regions are studied. The temporal distribution of CG lightning occurrence has two peak periods, one is from 13：00 to 21：00 （BT）, the other is from 23：00 to the next 05：00 （BT）. By analyzing the densities of total CG lightning and CG lightning during the different periods and peak periods, several areas with strong lightning activities are found. These areas are located over the mountains or over watersheds. Furthermore, lightning activities are much associated with water vapor condition of underlying surface. It is also found that there is obvious difference between the spatial distribution of positive CG lightning activity and negative CG lightning, indicating the difference in the charge structure of storms.