Zhang Xiaolin, Huang Yinbo, Rao Ruizhong, Wang Zhien
Key Laboratory of Atmospheric Composition and Optical Radiation, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China.
Opt Express. 2013 Jul 29;21(15):17849-62. doi: 10.1364/OE.21.017849.
Aerosol complex refractive index (ACRI) has attracted intensive attentions due to its significance in modeling aerosol radiative effects. Determinations of ACRI from surface measurements of aerosol scattering and absorption coefficients as well as number size distributions during June, 2008 based on an iterative Mie algorithm were performed. The aim of our study was to introduce an inversion approach with the merits of high time-resolutions to retrieve the optically effective ACRI, especially its imaginary part. Based on simultaneous measurements of aerosol characteristics, mean ACRI value of 1.50 ( ± 0.34)-i0.025 ( ± 0.015) at 550 nm in Hefei in summer was deducted. The lower imaginary parts with higher single scattering albedos and lower scattering Angstrom exponents were obtained for haze periods compared with nonhaze conditions with similar air-mass back-trajectories, indicating more large and scattering particles contributing to the formation of haze episodes. The derived imaginary parts of ACRI related to agricultural biomass burning were in the range from 0.013 to 0.029 at 550 nm. Significant negative correlations between retrieved imaginary parts of ACRI and measured single scattering albedos indicate that our retrieval approach is a reasonable method for determining the imaginary parts of complex refractive indices of aerosol particles.
气溶胶复折射率（ACRI）因其在气溶胶辐射效应建模中的重要性而备受关注。基于迭代米氏算法，利用2008年6月气溶胶散射和吸收系数以及粒径分布的地面测量数据，对ACRI进行了测定。本研究的目的是引入一种具有高时间分辨率优点的反演方法，以获取光学有效ACRI，特别是其虚部。基于气溶胶特性的同步测量，推算出夏季合肥550nm处的平均ACRI值为1.50（±0.34）-i0.025（±0.015）。与气团后向轨迹相似的非霾天气条件相比，霾天气下的虚部较低，单次散射反照率较高，散射埃指数较低，这表明有更多大粒径和散射粒子对霾天气的形成有贡献。在550nm处，与农业生物质燃烧相关的ACRI虚部范围为0.013至0.029。反演得到的ACRI虚部与测量的单次散射反照率之间存在显著负相关，这表明我们的反演方法是确定气溶胶粒子复折射率虚部的合理方法。
