沙尘气溶胶对云和降水影响的模拟研究

Effects of Sand Dust Particles on Cloud and Precipitation:A Numerical Study

采用二维分档云模式,对比背景大气气溶胶分布,讨论了扬沙和沙尘暴天气条件下矿物气溶胶对云微物理结构、光学特性以及降水形成的影响。结果表明:扬沙和沙尘暴天气增加大气中大核和巨核的浓度,促进云中水汽的活化,使降水提前出现,暖云和冷云降水量均大幅增加,但可忽略巨核增加对云光学厚度和反照率的作用;当矿物沙尘粒子同时作为有效的云凝结核和冰核参与云的发展时,冰核浓度增加使水成物有效半径减小,抑制了暖云和冷云降水,云内存留的大量冰晶增强云的光学厚度和反照率。

Using a two-dimensional spectral resolving cloud model, the effects of mineral dust particles, produced under different weather conditions, on development of cloud microphysical and optical properties and precipitation are simulated and compared with the results obtained under background aerosol conditions. The results show that dust particles raised during duststorms increase the amount of large and giant cloud condensation nuclei in the atmosphere, lead to more large droplets activated at the early stage of cloud formation, accelerate the formation of precipitation, and increase the amount of precipitation in both warm and cold clouds, while the influence of increasing in giant cloud condensation nuclei on the cloud optical properties and albedo can be neglected. The results also indicate that when sand dust acts as both cloud condensation nuclei and ice nuclei, increasing the initial concentration of ice nuclei results in a decrease in the effective radii of cloud particles, and inhibits precipitation formation. The increasing amount of ice nuclei enhances the cloud optical depth and albedo.