Analysis of lightning characteristics during a disaster-causing thunderstorm in Anhui Province

Atmospheric circulation and lightning characteristics during a disaster-causing thunderstorm occurred in Anhui province on August 19, 2017 were analyzed by using data from meteorological stations, ERA-Interim 0.5°×0.5° reanalysis, Himawari-8, Doppler radar in Anqing and ADTD lightning location system in Anhui province. Careful analysis of lightning disaster during the thunderstorm was made specially. The results show that (1) the thunderstorm occurred near the northern edge of subtropical high ridge and front of forward-tilted trough. Huang-Huai cyclonic shear at mid-low troposphere, low level jet and mesoscale surface convergence line are main affecting systems for the thunderstorm. And severe convection occurs under the condition of unstable atmospheric stratification. (2) The thunderstorm lasted about 4h, which covers Hefei and its neighboring areas and negative cloud-ground lightning is dominant during the thunderstorm. The ratio of positive and negative cloud-ground lightning is 1:25. (3)Most negative cloud-ground lightning occurred during the mature period of thunderstorm, and the positive cloud-ground lightning occurred frequently during the mature and dissipation period of thunderstorm. The percentage of cloud-ground lightning occurred in the echo region of 40-55 dBz is 78.2%. There is significant difference of distribution between positive and negative cloud-ground lightning. The concentrated areas of negative cloud-ground lightning are consistent with the strong echo area, while positive cloud-ground lightning are mostly distributed on the edge of the strong echo and weak echo area. (4)The lightning disaster is caused by a γ mesoscale convective cell at southern edge of the thunderstorm. The lightning disaster occurred in the mature segment of the cell. Lightning density around the disaster is 1 times·km^-2. Reason for the disaster is mainly due to not having enough time for people to avoid being hurt from lighting. It indicates that lightning disasters are not only related to the disaster factors as lightning, but the exposure, vulnerability degree and lightning protection level of the disaster body are also important factors for lightning disaster.