Numerical Simulation Study of the Evolution of Lightning Channel Decay and Reactivation Processes

Channel decay and reactivation are very common discharge phenomena, which have an important influence on the type, duration, and development of lightning discharges. However, how the electrical parameters in lightning channels change during reactivation processes and how reactivation affects the development of lightning leaders are still unclear. In this study, we employed the two-dimensional self-sustained charge neutrality lightning model to simulate the discharge process of intracloud lightning flashes and conducted an extensive analysis of channel decay and reactivation processes. Our results suggest a close correlation between the length of reactivated channels and the distribution of channel electrical parameters, and the reactivation process has a significant influence on lightning channel development. Specifically, it is found that greater charge accumulation at the reactivation starting point and higher residual conductivity of the decayed channels can lead to longer reactivated channels. And, the reactivation initiated from the positive leader end may both promote the resumption of the extension of the positive leader branch that has stopped extending and accelerate the propagation of an advancing positive leader. Moreover, reactivation may also activate the decayed negative leader channel, facilitating the lateral generation of new branches, which is crucial for the formation of hybrid lightning, needle-like structures, etc. The simulation results validate the previous speculations from observation studies regarding the potential influence of the reactivation process on lightning channel development and lay the foundation for the subsequent use of this model to explore the differences between the reactivation process initiated from the positive and negative leader end.