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

In terms of the observations from M-LDARS single stat ion 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 w atersheds.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.