基于VLF/LF三维闪电监测定位系统的北京闪电特征分析

利用北京地区VLF/LF三维闪电监测定位系统的2015年1月—2016年12月的数据资料，分析北京地区总闪、云闪和地闪的时空分布和电流强度特征。结果表明:（1）北京地区闪电主要发生在6—9月，峰值出现在7月；一天中闪电高发时段在15时—次日02时，总闪频数的日变化存在3个峰值，分别出现在15、20时和次日02时。（2）北京地区总闪密度高值区主要集中在两个区域:①门头沟区中南部至昌平区中西部山前一带；②密云、顺义和平谷三区交界的山前一带。云闪和地闪密度的大值区也基本出现在这两个区域。（3）云闪高度主要集中在9 km以下，且3~6 km的云闪频数最多；云闪高度约在15 km以下时，平均雷电流强度随云闪高度的增大而增大，而超过15 km的平均雷电流强度随云闪高度增大而减小。（4）闪电雷电流强度主要集中在5~50 kA，雷电流强度大于100 kA的闪电很少发生；闪电频数高的时段平均雷电流强度较小，闪电频数低的时段平均雷电流强度较大。 

ANALYSIS OF LIGHTNING CHARACTERISTICS IN BEIJING BASED ON VLF/LF 3D LIGHTNING LOCATION MONITORING SYSTEM

Based on the lightning data of VLF/LF 3D lightning location system from January 2015 to December 2016 in Beijing, the temporal and spatial characteristics of total lightning, intracloud lightning flashes(IC) and cloud-to-ground lightning flashes(CG) and the characteristic of the lightning current intensity were analyzed. The results are as follows. (1) Most lightning flashes occur between June and September, and the peak frequency occurs in July.The lightning flashes occur mostly from 15 BST of the day to 02 BST of the next day. There are three peaks in diurnal variation of total lightning, which is at around 15 BST, 20 BST and 02 BST of Next day. (2) There are two high value regions of spatial density of total flashes, and one is located in central and southern area of Mentougou and central and western area of Changping, the other is in the junction area among Miyun, Shunyi, and Pinggu. The high value regions of spatial density of IC and CG flashes have the distributions just as that of total flashes. The occurrence of high value regions of lightning density is mainly attributed to the local terrain uplift which is helpful to initiate or enhance thunderstorms. (3) The most IC occur at the height below 9 km and mainly concentrated in the height between 3 and 6 km. and when below about 15 km, the average intensity of lightning current is proportional to the height of IC. Otherwise, when above about 15 km, they are inversely proportional to each other. (4) The lightning current intensity is mainly concentrated in the 5~50 kA, and the lightning current intensity greater than 100 kA rarely occur. The averaged lightning current intensity is smaller when the lightning frequency is higher, and the averaged lightning current intensity is larger when the lightning frequency is lower.