Aerosol properties over an urban site in central East China derived from ground sun-photometer measurements
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- 作者：Qi Liu ; WeiDong Ding ; Lei Xie ; JinQiang Zhang ; Jun Zhu…
- 关键词：Aerosol optical thickness ; Single scattering albedo ; Central East China ; Sun ; photometer
- 刊名：Science China Earth Sciences
- 出版年：2017
- 出版时间：February 2017
- 年：2017
- 卷：60
- 期：2
- 页码：297-314
- 全文大小：
- 刊物主题：Earth Sciences, general;
- 出版者：Science China Press
- ISSN：1869-1897
- 卷排序：60
文摘
Sun-photometer measurements at Hefei, an urban site located in central East China, were examined to investigate the variations of aerosol loading and optical properties. It is found that aerosol optical thickness (AOT) keeps higher in winter/spring and gets relatively lower in summer/autumn. The large AOT in winter is caused by anthropogenic sulfate/nitrate aerosols, while in spring dust particles elevate the background aerosol loading and the excessive fine-mode particles eventually lead to severe pollution. There is a dramatic decline of AOT during summer, with monthly averaged AOT reaching the maximum in June and soon the minimum in August. Meanwhile, aerosol size decreases consistently and single scattering albedo (SSA) reaches its minimum in July. During summertime large-sized particles play a key role to change the air from clean to mild-pollution situation, while the presence of massive small-sized particles makes the air being even more polluted. These complicated summer patterns are possibly related to the three key processes that are active in the high temperature/humidity environment concentrating on sulfate/nitrate aerosols, i.e., gas-to-particle transformation, hygroscopic growth, and wet scavenging. Regardless of season, the increase of SSA with increasing AOT occurs across the visible and near-infrared bands, suggesting the dominant negative/cooling effect with the elevated aerosol loading. The SSA spectra under varying AOT monotonically decrease with wavelength. The relatively large slope arises in summer, reinforcing the dominance of sulfate/nitrate aerosols that induce severe pollution in summer season around this city.