Comparison of aerosol hygroscopicity and mixing state between winter and summer seasons in Pearl River Delta region, China
Comparison of aerosol hygroscopicity and mixing state between winter and summer seasons in Pearl River Delta region, China
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珠江三角洲地区冬夏季气溶胶吸湿性和混合状态对比
DOI：
10.1016/j.atmosres.2015.09.031
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发表时间：
2016-03
影响因子：
5.5
通讯作者：
Wu Dui
中科院分区：
文献类型：
--
作者：
Jiang Rongxin;Tan Haobo;Tang Lili;Cai Mingfu;Yin Yan;Li Fei;Liu Li;Xu Hanbing;Chan P. W.;Deng Xuejiao;Wu Dui
气溶胶颗粒的吸湿特性对于确定气溶胶尺寸分布非常重要，从而确定周围大气条件下的散射和吸收系数。在这项研究中，使用吸湿串联差分迁移率分析仪 (H-TDMA) 系统在冬季和夏季测量了中国广州市区气溶胶颗粒的吸湿特性。结果表明，城市气溶胶由强吸湿性、弱吸湿性和非吸湿性颗粒组成。对于直径为 40–200 nm 的吸湿性较小的颗粒，吸湿性参数 κLH 约为 0.15。对于吸湿性更强的颗粒，κMH 为 0.290 至 0.339，颗粒尺寸为 40 至 200 nm。对于非吸湿性颗粒，κNH约为0.015。研究发现，低吸湿性颗粒物（NFLH）的数量分数与大气氧化程度相关，大气氧化程度可由OC/EC表示。本文将冬季较大的 NFLH 归因于较高的 OC/EC 值（3.0）。这样的条件可能导致更多的吸湿性较低的颗粒的形成。后向轨迹聚类分析表明，气团来源与气溶胶吸湿性之间存在一定的联系，但似乎与污染程度无关。 NFNH的差异表明气溶胶颗粒的混合状态也会受到气团来源的影响。两个季节气溶胶吸湿参数的日变化表明，白天气溶胶颗粒往往具有较低程度的外部混合或准内部混合，导致较高的NFMH和较大的κmean；在夜间和清晨，它们往往在外部混合，导致较低的 NFMH 和较小的 κmean。这可以归因于大气老化效应和混合层高度的演变，并且意味着烟灰（非吸湿性）颗粒在离开城市环境时在很大程度上以内部混合物的形式存在。因此，仅假设区域气候模型和空气质量模型中烟尘颗粒的恒定混合状态（例如纯外部或内部）仍然不现实，并且可能会给中国三大经济区域之一的珠江三角洲地区带来不确定性。比较两季NFNH的日变化，似乎这种日循环主要与两季混合层演化的差异有关。亚微米颗粒的这种定量吸湿特性对于评估它们对天气气候效应和大气能见度的影响至关重要。
Hygroscopic properties of aerosol particles are important for determining aerosol size distributions, and thus determining scattering and absorption coefficients at ambient atmospheric conditions. In this study, hygroscopic properties of aerosol particles at an urban site in Guangzhou, China, were measured using a Hygroscopic Tandem Differential Mobility Analyzer (H-TDMA) system during the winter and the summer. The results show that the urban aerosols were composed of more-hygroscopic, less-hygroscopic and non-hygroscopic particles. For less-hygroscopic particles of 40–200 nm in diameter, the hygroscopic parameter κLHwas around 0.15. For more-hygroscopic particles, the κMHwas from 0.290 to 0.339 with a particle size from 40 to 200 nm. For non-hygroscopic particles, the κNHwas about 0.015. It was found that the number fraction of less-hygroscopic particles (NFLH) was correlated with the atmospheric oxidation which can be presented by OC/EC. This paper attributed the larger NFLHin winter to the higher value of OC/EC (3.0). Such conditions may lead to more formation of less-hygroscopic particles. Backward trajectories cluster analysis shows that there is a certain link between air mass origin and aerosol hygroscopicity, but it seems to be independent of the level of pollution. The difference of NFNHindicates that the mixing state of aerosol particles can also be affected by air mass origin. Diurnal variations in aerosol hygroscopic parameters in both seasons show that during daytime, aerosol particles tend to have a low degree of external mixing or quasi-internal mixing, resulting in a higher NFMHand a larger κmean; during nighttime and early mornings, they tend to be mixed externally, resulting in a lower NFMHand a smaller κmean. This can be attributed to atmospheric aging effect and evolution of mixing layer height and implies that soot (non-hygroscopic) particles present to a large extent as internal mixtures by the time they leave the urban environment. Hence, only assuming a constant mixing state of soot particles, such as pure external or internal for the regional climate model and air quality model is still not realistic and may lead to uncertainties for the Pearl River Delta (PRD) region which is one of the three major economic regions in China. Comparing the diurnal variation of NFNHin both seasons, it seems that such a diurnal cycle was mainly related to the differences in evolution of mixing layer between two seasons. Such quantitative hygroscopic properties of sub-micro particles are essential in assessing their impact on weather–climate effect and atmospheric visibility.
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影响因子：
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作者：
W. Malm;D. Day;S. Kreidenweis;J. Collett;Taehyoung Lee
通讯作者：
W. Malm;D. Day;S. Kreidenweis;J. Collett;Taehyoung Lee
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影响因子：
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作者：
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通讯作者：
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影响因子：
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作者：
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通讯作者：
Xu Xiangde;Zhou Xiuji;Shi Xiaohui
影响因子：
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作者：
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通讯作者：
Yerong Feng;Anyu Wang;Dui Wu;Xiangde Xu
影响因子：
5
作者：
TURPIN, BJ;HUNTZICKER, JJ
通讯作者：
HUNTZICKER, JJ