Coupling of Electrification and Discharge Processes with WRF Model and Its Preliminary Verification

The processes of cloud electrification and lightning parameterization are introduced into the Weather Research and Forecasting (WRF) model, in which the supercell and squall line are simulated. The numerical formulation of the electrical processes includes the noninductive graupel-ice, hail-ice, hail-snow and inductive graupel-cloud, hail-cloud charge separation mechanisms coupled with the Milbrandt two-moment microphysical scheme. In the mean time, a bulk lightning parameterization is considered in the model. On the one hand, the simulation of supercell produces a normal tripolar charge structure, consisting of a main negative charge region (-10℃ to-30℃) with an upper main positive charge region (-40℃ to-60℃) and a lower positive charge region (near 0℃). The maximum total charge density is approximately 2 nC/m³. The simulated vertical profile of charge structure is in accordance with the previous classical structure observed in the severe convective weather. On the other hand, the simulation of the squall line shows the inverted dipolar charge structure in some cells and the maximum total charge density is smaller than that of the supercell. Moreover, the simulated distribution of lightning density is similar to the observed cloud-to-ground (CG) lightning density in the mature stage of the squall line.