Source charge model and its application in simulation of lightning discharges

Source charge model is reviewed and is used to analyze electric field changes caused by eight directions of lightning streamers. Moreover, an improved piecewise-linear source charge model combined with the three-dimensional radiation source mapping results to interpret electric field changes on the ground is proposed. This model is applied to simulating E-field waveform and calculating electric parameters within initial streamer and the K event in an intracloud flash. The simulation result is consistent with the measured waveform. Mean charge line densities, currents and transferred charges of two processes are estimated: for the initial streamer, they are 0.53 C/km, 188.2 A, and 3.8 C, respectively; while for the K event, they are varying with the development of the channel.