Adaptive lightning progressing stochastic model with charge neutrality constraint for large-domain cloud-to-ground discharge

Abstract

This paper presents a new three-dimensional (3D) adaptive lightning progressing stochastic model (ALPSM) that incorporates the adaptive mesh refinement (AMR) method to enable a compatible simulation of large-domain intracloud discharges and near-ground lightning leader attachment processes. A new self-consistent charge neutrality maintenance algorithm is proposed, which considers the internal electric field of the lightning channel and ensures synchronized adjustments of the channel potential with the ambient potential. The model successfully reproduces the reported leader connection scenarios during the negative cloud-to-ground (−CG) lightning attachment process and analyzes the spatiotemporal evolutionary process of leader propagation and channel potential variation. The simulation results reveal a series of interesting phenomena in leader propagation before grounding: initial bidirectional vertical propagation during channel potential rapidly adjusting from the initial value to the average of the positive and negative charge regions; horizontal multibranch propagation within charge regions where the most concentrated height of horizontal propagation corresponds to the vertical electric field zero-crossing points; and downward negative leader vertical propagation during the rapidly increasing channel potential period. The ALPSM model advances the lightning stochastic model simulation owing to the charge neutrality constraint and adaptive mesh refinement in large three-dimensional domains, which provides a further method for the lightning attachment process simulation.