Analyses on the Characteristic of Cloud-to-Ground Lightning Flash in Da Hinggan Ling Forest Region

By using multi-station observations on thunderstorm in Da Hinggan Ling forest region which was conducted in the summer of 2009, the characteristics of cloud-to-ground (CG) lightning discharges were analyzed. The results show that 69% of 464 CG lightning flashes were single-stroke CG lightning flashes and the percent of positive CG lightning flashes was up to 22%. Statistics show that 27% of CG lightning flashes were followed by continuing current and single-stroke CG lightning flashes were usually followed by long continuing current. The mean duration of long continuing current is 127.4 milliseconds. Furthermore, results show that there is corresponding relationship among the duration of continuing current, the inter-stroke interval just preceding the interval containing continuing current, and the electric field change of stroke initiating continuing current: the smaller the inter-stroke interval just preceding the interval containing continuing current and the electric field change of stroke initiating continuing current, the longer the duration of continuing current. In addition, two positive CG lightning flashes have been calculated by using the nonlinear least-square method. The results show that the two positive CG lightning flashes occurred at 7.6 km and 7.0 km above mean sea level, respectively. And 38 coulombs quantity of electricity and 36 coulombs quantity of electricity have been neutralized during discharge process for these two flashes, respectively.