Establishment of a parameterization of lightning channel state changes and numerical simulation of lightning cut-off and re-breakdown

To improve the simulation capability of the numerical model for the fine lightning discharge process, complement the developing lightning detection technology, and explore the relationship between re-breakdown process and thunderstorm electrical parameters, a complete lightning parameterization scheme with a self-sustained charge neutrality is established. This scheme can simulate the cut-off and re-breakdown process of leader. Considering the polarity asymmetry, different extension velocities and initiation and propagation thresholds are set for positive and negative leaders respectively. New non-linear electrical parameters such as channel conductivity, average current, and charge are added to the scheme, and real-time updates of these parameters drive the development of lightning channel while different channel state change thresholds are also set. The real-time state changing leader channels, including decay, cut-off, and reactivation process, are simulated by all the above settings. Based on real-time changes in channel average current, longitudinal E-field and conductivity, charge is redistributed in the space to ensure the self-sustained charge neutrality of channels, which is an important basis for simulating the re-breakdown process. The new scheme is employed in the classical thunderstorm cloud model with tripolar charge structure, and the simulated IC flashes are in good agreement with existing observation facts in terms of channel structure, extinguishment and reactivation of the leader, and the polarity asymmetry of positive and negative leader. The verification against observation facts and some conceptual models indicates that the scheme is reasonable and advanced in simulating the complete lightning discharge process, including extinguishment and re-breakdown process under the premise of self-sustained charge neutrality.