Preliminary Modelling for the Effects of Dust on the Cumulus Electrification Process

Non-inductive electrification normally means charge transfer between ice particles through their collisions under a suitable environment. In particular, the collisions between ice crystals and graupel have been proven to be one of the main mechanisms of cloud charge production. As an important component of atmospheric ice nuclei, dust should play an important role in ice particle formation and cumulus cloud electrification. To study the impacts of different concentrations of dust on non-inductive electrification, two non-inductive electrification parameterization schemes (TAK scheme and SP98 scheme) were coupled into a 1.5 cloud-aerosol bin model. The prominent feature of this model is that the mass of cloud condensation nuclei and that of ice nuclei in each hydrometeor category can be determined. Simulations showed that both the charge density and the concentration of ice and graupel particles increased with increasing dust concentration, while the time of the initial electrification phenomenon advanced. Furthermore, both electrification schemes showed the dipole-type structure of the electric charges vertically as the observed distribution on 19 July 1981 for the Cooperative Convective Precipitation Experiment (CCOPE). However, only the SP98 scheme simulated the initiation of non-inductive electrification in the developing stage of this case.