沙尘模式中湿沉降过程的参数化及模拟试验

Parameterizing Wet Deposition in Sand & Dust Model and Numerical Simulating Using the Parameterized Model

在调研国内外固体气溶胶湿清除理论研究成果的基础上,从反映物理机制和实际可应用性两方面出发,设计了可考虑不同性质降水(降雨与降雪)拖曳作用的沙尘湿沉降参数化方案,并引入到沙尘模式中.选取2003年4月16～18日我国西北地区一次伴有降水的沙尘天气过程,进行了有无湿沉降方案的数值模拟对比试验,并针对两种降雨清除系数的简化方案做了敏感性试验.对试验的分析结果显示:降水拖曳作用引起的湿沉降对沙尘浓度的分布有比较明显的影响,这种影响从地面到对流层低层都有表现;在降水区,沙尘湿沉降速度与干沉降速度量级基本相当;在本例降水量较小的条件下,湿沉降对降雨清除系数简化方案的选取不很敏感.

Based on studying the domestic and international theory of dust ＆ sand aerosol＇s wet deposition, and considering both the physical mechanism and practicability, we designed a parameterized scheme for dust ＆ sand aerosol＇s wet deposition, which takes the pulling effects by both rain and snow into consideration. And we introduced this scheme into the dust ＆ sand model. Taking a dusty weather process as a test example, which was accompanied by precipitation and appeared in the northwestern part of China in April 2003, we carried out simulated numerical comparison tests using the parameterized scheme （in one test we considered the precipitation factor and the other we didn＇t）, analyzing and discussing the influence of wet deposition on space distribution of dust aerosols. In addition, we also performed two different schemes of susceptibility tests on rain cleansing. The result is： Over the precipitation area, the wet deposition caused by the precipitation pulling effect had a relatively noticeable influence on the distribution of dust ＆ sand aerosols. And this influence was found in the atmosphere from surface all the way to the low troposphere. As the precipitation level was relatively low, the wet deposition had almost the same effect as that of the dry deposition over the same area.