Influence of soot mixing state on aerosol light absorption and single scattering albedo during air mass aging at a polluted regional site in northeastern China
Influence of soot mixing state on aerosol light absorption and single scattering albedo during air mass aging at a polluted regional site in northeastern China
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DOI：
10.1029/2008jd010883
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发表时间：
2009-01
影响因子：
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通讯作者：
Yafang Cheng;M. Berghof;R. Garland;A. Wiedensohler;B. Wehner;T. Müller;H. Su;Y. Zhang;P. Achtert
中科院分区：
文献类型：
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作者：
Yafang Cheng;M. Berghof;R. Garland;A. Wiedensohler;B. Wehner;T. Müller;H. Su;Y. Zhang;P. Achtert
[1]气溶胶光学闭合研究进行了使用所观察到的高时间和尺寸分辨烟尘混合状态的挥发性串联差分迁移率分析仪（VTDMA）确定在污染的区域站点，玉法，在北京南部的2006年夏天。气溶胶吸收（σap，R = 0.9）和散射（σsp，R ≥ 0.95）的模拟值与实测值吻合较好。Yufa的烟尘混合状态通常可以通过VTDMA来确定，根据使用简单的光学模型结合球形均匀和核-壳涂层Mie代码来适当地预测σap。讨论了模型化σap中可能存在的不确定性。观察到快速的烟灰老化，这导致外部混合和涂覆的烟灰对σap的分数贡献变化很大。平均而言，约37%的σap（约10-60%）由涂覆的烟灰产生。由于在白天进行二次加工，涂层烟灰的σap和σsp的涂层增强可以在几个小时内达到8-10倍。这不仅是由于碳烟包覆层厚度的增加，也是碳烟由外混型向包覆型转变的结果。因此，假设区域气候模式的碳烟混合状态是不现实的，可能会导致不确定性。在东北重污染区，由于二次粒子的快速生成和凝结，气溶胶单次散射系数可能会迅速增加（高达0.90-0.95）。尽管同时进行的涂层处理增强了烟灰的光吸收能力，但还是发生了这种增加。
[1] An aerosol optical closure study was performed using the observed high time- and size-resolved soot mixing states determined by a Volatility Tandem Differential Mobility Analyzer (VTDMA) at a polluted regional site, Yufa, in the south of Beijing during the summer of 2006. Good agreement was found between the simulated and measured aerosol absorption (σap, R = 0.9) and scattering (σsp, R ≥ 0.95). The soot mixing state at Yufa can be generally determined by VTDMA, in terms of properly predicting the σap using a simple optical model combined with spherical homogeneous and core-shell coated Mie codes. The possible uncertainties in the modeled σap were discussed. Rapid soot aging was observed, which led to large variations in the fractional contributions to σap by externally mixed and coated soot. On average, about 37% of the σap (∼10–60%) arose by the coated soot. The coating enhancement in σap and σsp of the coated soot can reach up to a factor of 8–10 within several hours owing to the secondary processing during daytime. It was contributed not only by the increased thickness of coating shell, but also the transition of soot from externally mixed to coated one. Hence, assuming constant soot mixing state for the regional climate model is not realistic and may lead to uncertainties. In the highly polluted region in northeastern China, the aerosol single scattering albedo may increase very fast owing to the rapid secondary particle formation and condensation (up to 0.90–0.95). This increase took place although the concurrent coating processing enhanced the light absorption capability of soot.