@@ 1. Numerical Model and Experiment Setup 1.1. Description of the experiments A rainstorm occurred in Shanxi province, China, on June 13, 2007 is simulated using the Weather Research and Forecasting (WRF) mesoscale model coupled with the Morrision's double-moment bulk microphysical scheme (Morrison et al., 2005). The microphysics scheme predicts the number concentrations and mixing ratios of five hydrometeor species (cloud droplets, small ice, rain, snow, graupel) and includes a detailed treatment of droplet activation based on the scheme of Abdul-Razzak and Ghan (2000). The initial spectra of aerosol particles are given by three lognormal distribution functions and the size distributions of the hydrometeor species are represented by gamma functions. Two cases with different aerosol conditions are considered. A 'continental case' (C-case) and a 'polluted-continental case' (P-case). These cases are constructed by considering different fraction of aerosol particles are water soluble. Sensitivity tests are conducted and are compared to understand the response of cloud microphysical processes and precipitation to the changes in concentrations of aerosol particles.
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