Research on natural cloud-to-ground lightning flashes over a chinese inland plateau

During the summers of 2012 and 2013, field observations of lightning processes were conducted to investigate the characteristics of lightning discharges over a Chinese inland plateau. A total of 17 cloud-to-ground (CG) flashes were recorded by a high-speed video camera in 7 thunderstorm systems. Seven of the CG flashes had two or more contacts: 6 were multiple-channel flashes (MCFs) and 1 was a flash with multiple-ground-termination-stroke (MGTS). The percentage of CG flashes with multiple contacts was approximately 41% in Pingliang. The highest number of termination MCFs was three. The average percentage of such flashes recorded by the same camera in different regions of China was approximately 22%, ranging from 12% to 41%. The IC process before the return stroke occurred between the lower positive charge region and the middle negative charge region of the thunderstorm. Based on the optical images of the long-duration IC activity before the first stroke, it seems that the negative CG flashes can be initiated by a branch of a cloud flash or produced by a cloud flash.