Numerical simulation study of the reactivation process initiated from lightning negative leader channels

Given the limited understanding of the reactivation initiated from the lightning negative leader end, this study, by improving a self-sustained charge neutrality lightning model, successfully simulated the reactivation process initiated from negative leader channel under a classic tripole thunderstorm charge structure, and analyzed its discharge characteristics. The results show that two types of reactivation processes were initiated from the negative leader end: one is spontaneous initiation, corresponding to a “cumulative” pattern of electric field change. This is related to the outward extension of the negative leader channel, which transfers charges of opposite polarity to cutoff points. The simulated reactivation process of this type has a very limited effect on enhancing the electric field at the active negative leader head and does not significantly impact the subsequent extension of negative leader branches. The other is triggered initiation, corresponding to a “jump-increase” pattern of electric field change, which is triggered by the reactivation process initiated from the positive leader end. This type can be continuously initiated from the negative leader end until the electrostatic energy transferred from the positive leader end was fully dissipated. Overall, the reactivation processes initiated from the negative leader end are weaker than those initiated from the positive leader end in terms of initiation frequency, discharge intensity, and impact on the leader channel. Additionally, the electric field strength in the discharge channel corresponding to the reactivation process initiated from the negative leader end is typically only slightly above the reactivation initiation threshold, making it unable to sustain continuous breakdown in poorly conductive channels. This study not only enhances the capability of numerical models to simulate refined lightning discharge processes but also provides an effective means to reveal the key mechanisms causing significant differences between reactivation processes initiated from the positive and negative leader ends.