Atmospheric Chemistry and Physics Aerosol Physical and Chemical Properties Retrieved from Ground-based Remote Sensing Measurements during Heavy Haze Days in Beijing Winter
Atmospheric Chemistry and Physics Aerosol Physical and Chemical Properties Retrieved from Ground-based Remote Sensing Measurements during Heavy Haze Days in Beijing Winter
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通讯作者：
Z. Li;X. Gu;L. Wang;D. Li;Y. Xie;K. Li;O. Dubovik;G. Schuster;P. Goloub;Y. Zhang-Y.-Zha
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作者：
Z. Li;X. Gu;L. Wang;D. Li;Y. Xie;K. Li;O. Dubovik;G. Schuster;P. Goloub;Y. Zhang-Y.-Zha
近三十年来，随着经济的发展，中国东部和西南部的许多大城市的灰霾事件和大气污染日益严重，对区域环境乃至气候造成了重大影响。然而，对灰霾天气下气溶胶物理化学性质的认识还很不足。选取2011年和2012年发生在北京的两次冬季灰霾天气，利用地面遥感资料对灰霾天气进行了研究。利用CIMEL CE 318太阳-天空辐射计反演了霾气溶胶的光学、物理和化学性质，包括气溶胶光学厚度（AOD）、粒径分布、复折射率和气溶胶组分（黑碳（BC）、棕碳（BrC）、矿物尘（DU）、硫酸铵（AS）组分和气溶胶含水量（AW））。对5个灰霾日的反演结果表明，两次灰霾天气的气溶胶含量和气溶胶性质具有可比性。因此，得出平均重雾特性参数，为未来研究提供研究案例。在440 nm处的平均AOD约为3.0，并且在440至870 nm的范围内，平均AOD指数为1.3。精细模式AOD为2.8，对应于0.93的精细模式分数。在冬季灰霾事件中，粗颗粒在双峰粒径分布中占据了相当大的体积分数，细模式和粗模式的平均颗粒半径分别为0.21和2.9 µm。折射率的真实的部分表现出相对平坦的光谱行为，从440到1020 nm的平均值为1.48。虚部表现出光谱变化，在440 nm处的值（约0.013）高于其他三个波长（在675 nm处约0.008）。气溶胶成分反演结果表明，在调查的灰霾事件中，BC，BrC，DU，AS和AW的体积分数平均分别为1，2，49，15和33%。初步的不确定性估计和比较，这些遥感结果与现场BC和PM 2.5测量的文件。
With the increase in economic development over the past thirty years, many large cities in eastern and southwestern China are experiencing increased haze events and atmospheric pollution, causing significant impacts on the regional environment and even climate. However, knowledge on the aerosol physical and chemical properties in heavy haze conditions is still insufficient. In this study, two winter heavy haze events in Beijing that occurred in 2011 and 2012 were selected and investigated by using the ground-based remote sensing measurements. We used a CIMEL CE318 sun– sky radiometer to retrieve haze aerosol optical, physical and chemical properties, including aerosol optical depth (AOD), size distribution, complex refractive indices and aerosol fractions identified as black carbon (BC), brown carbon (BrC), mineral dust (DU), ammonium sulfate-like (AS) components and aerosol water content (AW). The retrieval results from a total of five haze days showed that the aerosol loading and properties during the two winter haze events were comparable. Therefore, average heavy haze property parameters were drawn to present a research case for future studies. The average AOD is about 3.0 at 440 nm, and the Ångström exponent is 1.3 from 440 to 870 nm. The fine-mode AOD is 2.8 corresponding to a fine-mode fraction of 0.93. The coarse particles occupied a considerable volume fraction of the bimodal size distribution in winter haze events, with the mean particle radius of 0.21 and 2.9 µm for the fine and coarse modes respectively. The real part of the refractive indices exhibited a relatively flat spectral behavior with an average value of 1.48 from 440 to 1020 nm. The imaginary part showed spectral variation, with the value at 440 nm (about 0.013) higher than the other three wavelengths (about 0.008 at 675 nm). The aerosol composition retrieval results showed that volume fractions of BC, BrC, DU, AS and AW are 1, 2, 49, 15 and 33 %, respectively, on average for the investigated haze events. The preliminary uncertainty estimation and comparison of these remote sensing results with in situ BC and PM 2.5 measurements are also presented in the paper.