[Impact of Collision Removal of Rainfall on Aerosol Particles of Different Sizes].
[Impact of Collision Removal of Rainfall on Aerosol Particles of Different Sizes].
复制标题
DOI：
10.13227/j.hjkx.2016.10.002
复制
发表时间：
2016-10
期刊：
影响因子：
--
通讯作者：
Qun Dong;P. Zhao;Yi-na Chen
中科院分区：
文献类型：
--
作者：
Qun Dong;P. Zhao;Yi-na Chen
结合2012年10月至2014年10月海淀区逐时PM2.5浓度和气象数据，以及某一降雨过程的粒径分布数据，通过计算Stokes数，分析降雨碰撞去除对不同粒径气溶胶颗粒的影响。Stokes数的计算结果表明，雨滴对小于2 μm的气溶胶颗粒的直接碰撞去除作用不大，而对大于2 μm的气溶胶颗粒的直接碰撞去除作用较大。通过对观测资料的统计分析，PM2.5显著下降的降水过程或降水时数相当有限。而PM2.5浓度在43.2%的降水时数中呈上升趋势。通过对典型降水过程中气溶胶颗粒粒径分布数据的分析，发现降水对Aitken模式颗粒（1.0 μm）具有显著的清除作用，而对累积模式颗粒则不具有清除作用。由于累积模式气溶胶贡献了PM2.5的大部分质量，降雨过程对PM2.5的碰撞清除影响较小。
The impact of collision removal of rainfall on aerosol particles of different sizes was analyzed through the calculation of Stokes number, combining with the hourly PM2.5 concentrations and meteorological data in Haidian from October 2012 to October 2014, and also the size distribution data in a selected rainfall process. The calculation results of Stokes number showed that the raindrops had little effect on direct collision removal of aerosol particles of smaller than 2 μm, and had more effect on aerosol particles of larger than 2 μm. Based on the statistical analysis of the observation data, the precipitation processes or the precipitation hours with significantly decreased PM2.5 were quite limited. However, PM2.5 concentrations were increased in 43.2% of the precipitation hours. By analyzing the size distribution data of aerosol particles during a typical precipitation process, we found that the precipitation had significant scavenging effect on Aitken mode particles (1.0 μm), except for the accumulation mode particles. Since the accumulation mode aerosols contributed most of the mass of PM2.5, the rainfall processes only had minor influence on the collision scavenging of PM2.5.