| 降雨对不同粒径气溶胶粒子碰撞清除能力 |
| 摘要点击 3039 全文点击 1432 投稿时间：2016-04-18 修订日期：2016-05-17 |
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| 中文关键词 PM2.5 湿清除 惯性碰撞 斯托克斯数 粒径分布 |
| 英文关键词 PM2.5 wet scavenging inertial collision Stokes number size distribution |
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| 中文摘要 |
| 利用与惯性碰撞紧密相关的斯托克斯数Stk计算公式，结合海淀宝联大气成分站和海淀自动观测站2012年10月~2014年10月两年实测的逐时PM2.5浓度数据和对应时刻的气象要素数据，并挑选典型降水过程分析降水对不同粒径气溶胶的碰撞清除作用. 惯性碰撞是降水对气溶胶的最主要清除方式，斯托克斯数Stk的计算结果显示，降水对粒径小于2 μm的气溶胶的直接碰撞清除作用很小，对粒径大于2 μm的粗粒子的清除作用相对较大；实际观测数据统计分析表明，PM2.5浓度明显减少的降水过程及降水时次很少，而43.2%的降水时次PM2.5浓度有所升高；通过对典型降水过程气溶胶粒径分布数据分析表明，降水对爱根核模态（<0.1 μm）和粗模态气溶胶（>1.0 μm）有明显的清除作用，但对积聚模态清除作用不明显，由于PM2.5的质量浓度主要分布在积聚模态，因此，降水对环境中PM2.5的碰撞清除作用很弱. |
| 英文摘要 |
| 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 (<0.1 μm) and coarse 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. |
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