A three-dimensional downward leader model incorporating geometric and physical characteristics

摘要

In this paper, a three-dimensional, stochastic model of a lightning downward leader is proposed. The background electric field in which the downward leader propagates is used to determine the direction of propagation. The critical background electric field for the development of a downward leader was obtained by extrapolating the results of negative long air gap discharge experiments. The distribution of charge in the downward leader was modelled with the charge simulation method. The calculation took into account branching of the leader channel. By choosing a suitable value of the probability exponent, the simulation results of fractal dimension and charge in the downward leader are shown to closely match observational data of lightning. Finally, the model was used to reproduce a negative ground flash. The ground electric field calculated by the model was found to agree well with measurement results from the field.