| The results of domestic and abroad observations and researches show that mineral aerosols are coated with soluble sulfate by heterogeneous-phase chemical processes during the transmission of mineral aerosols. The concentration of S in atmosphere is high during dust storm seasons in China, accordingly mineral particles could be coated with (NH4)2SO4 by heterogeneous-phase chemical processes in suitable moisture condition. There are two aspects to discuss effects of mineral aerosols on regional precipitation in the paper.(1) Considering mineral aerosols coated with (NH4)2SO4 as CCN, the rule of the condensation growing process of droplet is discussed first. Using the aerosol airborne data in Liaoning on May 14, 1997, the cloud drop size distribution are calculated from mineral aerosols coated with (NH4)2SO4 and pure (NH2)2SO4 nuclei separately. Comparison shows that the cloud drop size distribution from mineral aerosols coated with (NH4)2SO4 are wider than the one from pure (NH4)2SO4 nuclei and agrees well with the observation. Consequently, mineral aerosols coated with (NH4)2SO4 play an important role in cloud microphysics.(2) Using NCEP 1×1 global Final Analysis Data, the dust storm occurring in North China during April 8-11, 2003 was simulated by MM5 V3-7 system to study effects of mineral aerosols on regional precipitation. Beacause two sites are both backward position with severe pollution of S during the transmission of mineral aerosol, considering the effect of cloud drop equilibrium vapour pressure on qvsw, saturation mixing ratio for water vapour with respect to water, six experiment schemes are designed based on foregoing effects of mineral aerosols on cloud microphysics. The result of the simulation, such as temperature, water vapor mixing ratio, accumulated rainfall in past 6 hour, snow mixing ratio and rain water mixing ratio are analyzed to investigate the relationship between mineral aerosols and cold cloud precipitation, and to probe into the mechanism that how mineral aerosols effect on cloud and precipitation in backward position. The result of analysis shows that 1.comparing with scheme A in control experiment, the amount and scope of regional precipition increase in past 24 hour in sensitivity experiment schemes;2.consideringcloud drop equilibrium vapour pressure, the amount of precipitation increases in the aera where humidity and temperature are appropriate;3.the mechanism of effects on regional precipitation is that considering cloud drop equilibrium vapour pressure accelerates Bergeron effect and rain water and cloud ice collisions.
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