Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
doi:10.5194/acp-2016-1175
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
16 Feb 2017
Review status
This discussion paper is under review for the journal Atmospheric Chemistry and Physics (ACP).
Chemical composition and droplet size distribution of cloud at the summit of Mount Tai, China
Jiarong Li1, Xinfeng Wang1, Jianmin Chen1,2,3, Chao Zhu1, Weijun Li1, Chengbao Li2, Lu Liu1, Caihong Xu1, Liang Wen1, Likun Xue1, Wenxing Wang1, Aijun Ding3, and Hartmut Herrmann2,4 1Environment Research Institute, School of Environmental Science and Engineering, Shandong University, Ji'nan 250100, China
2Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Institute of Atmospheric Sciences, Fudan University, Shanghai 200433, China
3Institute for Climate and Global Change Research, School of Atmospheric Sciences, Nanjing University, Nanjing 210023, Jiangsu, China
4Leibniz Institute for Tropospheric Research (TROPOS), Atmospheric Chemistry Department (ACD), Permoserstr. 15, D-04318, Leipzig, Germany
Abstract. Chemical composition of 39 cloud samples and droplet size distribution in 24 cloud events were investigated at the summit of Mt. Tai from July to October 2014. Inorganic ions, organic acids, metals, HCHO, H2O2, sulfur(IV), organic carbon, element carbon as well as pH and electrical conductivity were analyzed. The acidity of the cloud water significantly decreased from a reported value of pH 3.86 in 2007–2008 (Guo et al., 2012) to pH 5.87 in the present study. The concentrations of nitrate and ammonium were both increased since 2007–2008, but the overcompensation of ammonium led to the increase of the mean pH value. The microphysical properties showed that cloud droplets were smaller than 26.0 μm and the most were in the range of 6.0–9.0 μm. The maximum droplet number concentration (Nd) was associated with droplet sizes of 7.0 μm. Cloud droplets exhibited a strong interaction with atmospheric aerosols. High PM2.5 level resulted in higher concentrations of water soluble ions and smaller sizes with more numbers of cloud droplets, and further gave rise to relatively high acidity. High degrees of relative humidity facilitated the formation of large cloud droplets and led to high liquid water contents under low PM2.5 level. The cloud droplets to wet deposition acted as an important sink of soluble material in the atmosphere and the dilution effect of the water content should be considered when estimating concentrations of soluble components in the cloud phase.

Citation: Li, J., Wang, X., Chen, J., Zhu, C., Li, W., Li, C., Liu, L., Xu, C., Wen, L., Xue, L., Wang, W., Ding, A., and Herrmann, H.: Chemical composition and droplet size distribution of cloud at the summit of Mount Tai, China, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2016-1175, in review, 2017.
Jiarong Li et al.
Jiarong Li et al.
Jiarong Li et al.

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Short summary
Cloud events were monitored to investigate the chemical composition and size distribution of cloud droplets at Mt. Tai. Obvious rise of pH value was found for elevated NH4+ last decade. Higher PM2.5 level resulted in higher concentrations of water soluble ions and smaller sizes with more numbers of cloud droplets. The mechanisms of cloud droplet formation and the mass transfer between aerosol-gas-cloud phases were summarized to enrich the knowledge of cloud chemical and microphysical properties.
Cloud events were monitored to investigate the chemical composition and size distribution of...
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