Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing 210044, China; Plateau Atmosphere and Environment Key Laboratory of Sichuan Province, College of Atmospheric Science, Chengdu University of Information Technology, Chengdu 610225, China.
Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing 210044, China.
J Environ Sci (China). 2019 Sep;83:21-38. doi: 10.1016/j.jes.2019.03.013. Epub 2019 Mar 26.
In-situ measurements of aerosol optical properties were conducted at Mt. Huang from September 23 to October 28, 2012. Low averages of 82.2, 10.9, and 14.1 Mm for scattering coefficient (σ), hemispheric backscattering coefficient (σ), and absorption coefficient (σ), respectively, were obtained. Atmospheric aging process resulted in the increase of σ but the decrease of the single scattering albedo (ω) at constant aerosol concentration. However, the proportion of non-light-absorbing components (non-BCs) was getting higher during the aging process, resulting in the increase of aerosol diameter, which also contributed to relatively higher σ and ω. Diurnal cycles of σ and σ with high values in the morning and low values in the afternoon were observed closely related to the development of the planetary boundary layer and the mountain-valley breeze. BC mixing state, represented by the volume fraction of externally mixed BC to total BC (r), was retrieved by using the modified Mie model. The results showed r reduced from about 70% to 50% when the externally mixed non-BCs were considered. The periodical change and different diurnal patterns of r were due to the atmospheric aging and different air sources under different synoptic systems. Local biomass burning emissions were also one of the influencing factors on r. Aerosol radiative forcing for different mixing state were evaluated by a "two-layer-single-wavelength" model, showing the cooling effect of aerosols weakened with BC mixing state changing from external to core-shell mixture.
2012 年 9 月 23 日至 10 月 28 日，在黄山进行了气溶胶光学特性的现场测量。得到了散射系数（σ）、半球反向散射系数（σ）和吸收系数（σ）的平均值分别为 82.2、10.9 和 14.1 Mm。大气老化过程导致散射系数（σ）增加，但在气溶胶浓度不变的情况下，单散射反照率（ω）降低。然而，在老化过程中非吸光成分（非 BC）的比例越来越高，导致气溶胶直径增加，这也导致了相对较高的 σ 和 ω。σ 和 σ 的日变化与边界层和山谷风的发展密切相关，早上值高，下午值低。利用改进的 Mie 模型反演了 BC 的混合状态，以外部混合 BC 与总 BC 的体积分数（r）表示。结果表明，当考虑外部混合的非 BC 时，r 从约 70%降低到 50%。r 的周期性变化和不同的日变化模式是由于大气老化和不同天气系统下不同的空气源造成的。局地生物质燃烧排放也是 r 的影响因素之一。通过“两层单波长”模型评估了不同混合状态下的气溶胶辐射强迫，结果表明气溶胶的冷却效应随着 BC 混合状态从外部混合向核壳混合物的变化而减弱。
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