根据气溶胶成分的光学特性,气溶胶可简化为5种成分组成:一类是吸收性的成分,包括黑碳BC、吸收性有机碳BrC、沙尘DU;另一类是散射性成分硫酸铵AS;还有一类是气溶胶中的重要成分——水分AW。本文基于太阳-天空辐射计获取的气溶胶微物理特性资料,对北京2013年1月灰霾过程气溶胶中这5种成分的含量进行了定量反演研究。结果表明,灰霾天气下气溶胶中BC、BrC、DU、AS和AW的体积比例为2%、9%、30%、33%和26%,而清洁天气分别为3%、3%、15%、71%和8%。对于质量浓度,灰霾天气下BC、BrC、DU、AS和AW分别是7、35、166、131和73 mg/m²;而清洁天气下分别为4、4、29、78和6 mg/m²,两者的成分比例有显著差别。反演的黑碳质量浓度,以及细粒子的质量浓度分别与黑碳仪的观测和环保部公布的PM_2.5的质量浓度具有很好的一致性,相关系数R²分别为0.45和0.85。

According to the aerosol optical properties, the aerosol chemical composition can be simplified as a mixture of five components. They are three absorbing components like Black Carbon (BC), Brown Carbon (BrC), and dust (DU); one scattering (non-absorbing) component of ammonium sulfate (AS) as well as aerosol water (AW), which is responsible for aerosol hygroscopic characteristics. In this study, we estimate the contents of the five chemical components of haze aerosols during January 2013 over Beijing from the ground-based remote sensing measurements. We find that BC, BrC, DU, AS and AW occupy 2%, 9%, 30%, 33%, and 26% in volume, respectively on average for the selected haze days, while they are 3%, 3%, 15%, 71%, and 8% on average for the selected clear days. As for the column mass concentration, BC, BrC, DU, AS and AW in the haze aerosol are 7, 35, 166, 131, and 73 mg/m² on average, while during the clear days they are 4, 4, 29, 78 and 6 mg/m² on average. The comparisons of these remote sensing results with in situ BC and PM_2.5 measurements are also presented in the paper. Results show that the retrievals agree well with the measurements, with coefficient R² 0.45 for BC and 0.85 for PM_2.5.