2008-2010年北京地区云地闪时空分布特征

Temporal and Spatial Distribution Characteristics of Cloud-to-ground Flash from 2008 to 2010 in Beijing

利用北京地区ADTD地闪定位资料,分析了2008 2010年北京地闪的时空分布特征。研究发现,正地闪次数占总地闪次数的6%,地闪的平均电流强度为24.55 kA,正地闪的平均电流强度为负地闪的3倍。北京地区地闪月变化呈双峰结构,频次高峰月份为6—8月,正地闪呈单峰结构,峰值出现在7月。日变化的闪电频次高峰期主要出现在16 19时和00 05时两个时段。地闪频次高的区域主要集中在密云、平谷、顺义东北部和房山西部。有些地区呈现出地闪密度不高,但高回击电流的地闪频次和比例较高的特点。

Using the data of ADTD ground flash location system,we analysis the temporal and spatial distribution of cloud-to-ground（CG） flash in Beijing.The study show that the positive CG flash accounts for 6% of total CG flash,the average current intensity of the total flash is 24.55 kA,and the average current intensity of the positive CG flash is three times of which of negative CG flash.Monthly variation of CG flash presents a double-peak structure.High occurrence of CG flash appears from June to August.Monthly variation of positive CG flash shows a single peak structure which occurs in July.Frequency peak of the diurnal variation of lightning occurs mainly in two periods which appear from 16：00 to 19：00 and 0：00 to 5：00.High incidence of CG flashes mainly concentrates in Miyun,Pinggu,northeast of Shunyi and south of Fangshan.In some areas,the overall CG flash density is not high,but the frequency and proportion of high-return stroke current is high.