Abstract:Based on the observation data of the Zhejiang ADTD lightning location system (from 2007 to 2018), the spatial and temporal distribution characteristics of cloudtoground (CG) lightning are analyzed. Considering both CG lightning density and intensity, an analysis of lightning disaster causing risk is made. The results show that the number of thunderstorm days per year and the percentage of positive CG lightning each year both have a rising tendency during the 12 years. The CG flashes mainly occur from 12:00 to 20:00, June to September. In spring, the proportion of positive CG lightning is much higher, while the most of flashes occur in the evening and at night. In summer, there are many abnormally high values of daily lightning density and lightning area, while the peak hour of daily lightning is mainly in the afternoon. The spatial distribution of higher CG lightning density area varies from west to east with season changes. It is also found that the average CG lightning density over the years is higher in the central Zhejiang than in north and south parts. The amplitude of CG lightning current is mainly distributed from 15 to 45 kA. The average value of CG lightning intensity is the highest in Zhoushan (44.49 kA), while the lowest in Taizhou (32.69 kA). The spatial distribution characteristics of lightning intensity and density are different. It suggests that the very high lightning disastercausing risk level locates in the coastal area of the eastern Zhejiang, HangzhouShaoxing border, northwestern Wenzhou, central Zhejiang and western Zhejiang. The spatial distribution characteristics of disaster causing risk level are consistent with the number of historical lightning disasters as well as the total number of casualties.
