NUMERICA STUDY OF THUNDERSTORM ELECTRIFICATION WITH A THREE-DIMENSIONAL DYNAMICS AND ELECTRIFICATION COUPLED MODEL—MODEL DESCRIPTION AND PARAMETERIZATION OF ELECTRICAL PROCESSES^*

A new three-dimensional dynamics and electrification coupled model has been developed for investigating the characteristics of microphysics,dynamics and electrification inside thunderstorms.This model is basically modified from a three-dimensional,time-dependent,and dual-parameter cloud model originally established in IAP (Institute of Atmospheric Physics) and a two-dimensional axisymmetric cloud dynamics and electrification coupled model.Primary modifications to the model include not only the coupling of electrification with dynamical and microphysical processes,but also the lightning discharge process and screening layer effect at the cloud top as well.Apart from including a full treatment of small ions with attachment to six classes of hydrometeors,the inductive and non-inductive charging mechanisms are more specifically considered.A case simulation of July 19.1981 CCOPE is performed aiming to validate the potential capability of the model.Comparison between model results and observations reveals that the model has the capacity to reproduce many of the observed characteristics of thunderstorms in dynamical,microphysical,and electrical aspects.