102 ACTA METEOROLOGICA SINICA VOL.19 Numerical Analysis of Eects of Atmospheric Ice Nuclei Concentrations on Radiant Properties of Cold Clouds

Numerical simulations of 18 precipitation days from June to September in 1996 with the 3D convective cloud model of CAMS (Chinese Academy of Meteorological Sciences, Version 2000) were conducted. In these simulations, the concentration of IN (ice nuclei) was assumed to increase by 5 times. The results show that when IN concentrations increase, the amounts of precipitation decrease, cloud tops heighten and the areas of cloud tops increase in 80 percent simulated clouds. Moreover, in 95 percent simulated clouds, the sizes of ice crystals in clouds decrease and quantities increase. These results mean that the physical properties of clouds will change when IN concentration increases. The radiant properties of clouds and climate may also change directly and indirectly