A study on characteristics of spatial and temporal distribution of cloud-to-ground flashes in Hainan Island

Based on the cloud-to-ground (CG) flashes data from 2010 to 2013 obtained- by the VLF lightning locating networks in Hainan Province, the temporal and spatial characteristics of cloud-to-ground (CG) flashes activities were analyzed. The results indicated that more than 99% of CG flashes occurred between April and October and two peaks of CG activity appeared in May (23%) and August (30%).The CG flashes occur clearly with a characteristic of daily and monthly variation, in which there are two peaks. The peaks of daily variation occur at 5:00 am and 16:00 (Beijing time) almost. In terms of areas, the CG activities in the most coastal areas present the changing characteristic of double peaks. However, there is only a single peak in the inland areas and the northern coastal areas near the Qingzhou Strait. The first peak (the early peak) occur between 2:00 and 7:00 am, and the second one (the late peak) occur during the period from 12:00 to 17:00, where the CG activities present the double-peak characteristic. The spatial distribution of CG flashes presents certain regularity that the CG flashes density is the largest in the inland mountainous areas and the density becomes more and more small as the spatial position further outspread forward the coastal areas. In addition, there are two high value centers of the CG flashes density, and the spatial distribution of flashes density exist differences at different times especially in the south of Hainan Island and on the north of Wuzhishan mountain.