基于地基遥感的降水过程对城市型气溶胶差异性影响分析

The influence analysis of precipitation on aerosol in urban area based on ground-Based remote sensing observations

降水过程对气溶胶粒子的影响非常复杂.为了研究降水对城市大气中气溶胶粒子的差异性影响,该文选择2016年6~7月武汉市一次持续性强降水过程进行分析.结合OPAC模型及GADS数据集,利用最小二乘线性回归算法,基于CE-318太阳光度计及黑碳仪观测数据对大气中三种城市气溶胶粒子(不溶性气溶胶粒子INSO、水溶性气溶胶粒子WASO、黑碳气溶胶SOOT)的粒子数密度进行反演,并使用光学特性误差及黑碳仪观测结果对反演结果进行验证,显示了较高的反演精度.通过对比降水前后不同气溶胶粒子数量的变化,发现降水对INSO、WASO、SOOT三种气溶胶的影响效果及时长存在明显差异.降水对WASO、INSO、SOOT均有明显的抑制作用,但影响时长存在明显差异.降水对SOOT的消减作用仅能持续数小时.WASO在降水后逐渐回升,其抑制作用仅能持续一周即回复到降水前,降水对INSO消减作用的持续时间最长,可达数周之久.

It is rather complicated how precipitation impacts on the mass concentration of aerosol particles in urban area.As an area dominated by urban aerosol particles,Wuhan is one of the major city in China.A persistent heavy rainfall there in 2016 were chosen to analyze the rainfall-caused concentration changes of three types typical aerosol particles,Water-insoluble Aerosol Particles(INSO),Water Soluble Aerosol Particles(WASO)and Black Carbon Aerosol(or SOOT).After the optical property interpolation of three channels,ground-based CE-318 sun-sky radiometer observations was used to inverse the aerosol particles number density of these three types of aerosol based on the least squares linear regression.Besides,GADS dataset were used to derive the corresponding mass concentration of INSO,WASO and SOOT.To validate the inversion accuracy,the theoretical optical property parameters including SSA、AOD and ASYM were used as the reference.The results showed the inversion methods has rather good performance.Furthermore,the different effect of precipitation on the three types aerosol was also found.The rainfall has significant reduction impact on WASO,INSO and SOOT.However,the duration of the reduction effect have significant difference among these three types aerosols.WASO recovered gradually after the precipitation,its ratio in total aerosol mass increased significantly and achieved to 88.30%.As for INSO,precipitation’s suppression effect can lasts for a long time,up to several weeks.The rainfall effect of SOOT only can last several hours,and it is very limited to improve the atmospheric environment.Due to the increased probability of acid rain,the rainfall effect on WASO should get more attention in a city as Wuhan.