Coupling Of Electrification And Discharge Processes With WRF Model And Its Verification

The processes of cloud electrification and lightning parameterization are introduced intothe Weather Research and Forecasting (WRF) model, in which the supercell, squall line andtyphoon are simulated. The numerical formulation of the electrical processes includes thenoninductive graupel-ice, hail-ice, hail-snow and inductive graupel-cloud, hail-cloud chargeseparation mechanisms coupled with the Milbrandt two-moment microphysical scheme. Inthe mean time, a bulk lightning parameterization is considered in the model.On the one hand, the simulation of supercell produced a normal tripolar charge structure,consisting of a main negative charge region (-10oC to-30oC) with an upper main positivecharge region (-40oC to-60oC) and a lower positive charge region (near0oC). The maximumtotal charge density is approximately2nc/m3. The simulated vertical profile of chargestructure is in accordance with the previous classical structure observed in the severeconvective weather.On the other hand, the simulation of the squall line showed the inverted dipolar chargestructure in some cells and the maximum total charge density is smaller than that of thesupercell. The result also showed that the charge separation process take place mainly belowthe level of charge reversal, hence the graupel particles charged positively and the iceparticles charged negatively, leading to the reverse of the charge structure. Moreover, thesimulated distribution of lightning density is similar with observed cloud-to-ground (CG)lightning density in the mature stage of the squall line. While the predicted distribution of theaccumulative rainfall and lightning activity with assimilation of radar data are more similarwith the observation.The simulation of typhoon indicated that the simulative distribution of the CG lightningactivity is close to the observation in outer rain band. In the inner rain band, No CG lightningwas detected by the CG lightning location system, whereas the simulation showed somelightning activity which suggested that the intra-cloud lightning activity may exist in innerrain band.