A new snow microphysics parameterization applied to a cloud electrification model: framework and preliminary results

A cloud electrification scheme and a new snow parameterization are presented. The cloud electrification framework is applied to a double-moment bulk microphysics 3-dimensional model. The rain and graupel are predicted using a gamma size distribution with a fixed value of dispersion parameter. To predict the snow a more sophisticated approach is implemented with a dispersion parameter computed each time step in terms of mixing ratio of snow. An ice-ice non inductive electrification scheme is used involving the interaction between the graupel, ice crystals and supercooled cloud droplets. It is applied a simple lightning parameterization that computes the net charge balance of the thundercloud due to the discharge. Sensitivity tests are performed for some cases of deep convection and preliminary results are presented.