Articles | Volume 17, issue 13
https://doi.org/10.5194/acp-17-8473-2017
https://doi.org/10.5194/acp-17-8473-2017
Research article
 | 
12 Jul 2017
Research article |  | 12 Jul 2017

In situ chemical composition measurement of individual cloud residue particles at a mountain site, southern China

Qinhao Lin, Guohua Zhang, Long Peng, Xinhui Bi, Xinming Wang, Fred J. Brechtel, Mei Li, Duohong Chen, Ping'an Peng, Guoying Sheng, and Zhen Zhou

Abstract. To investigate how atmospheric aerosol particles interact with chemical composition of cloud droplets, a ground-based counterflow virtual impactor (GCVI) coupled with a real-time single-particle aerosol mass spectrometer (SPAMS) was used to assess the chemical composition and mixing state of individual cloud residue particles in the Nanling Mountains (1690 m a. s. l. ), southern China, in January 2016. The cloud residues were classified into nine particle types: aged elemental carbon (EC), potassium-rich (K-rich), amine, dust, Pb, Fe, organic carbon (OC), sodium-rich (Na-rich) and Other. The largest fraction of the total cloud residues was the aged EC type (49.3 %), followed by the K-rich type (33.9 %). Abundant aged EC cloud residues that mixed internally with inorganic salts were found in air masses from northerly polluted areas. The number fraction (NF) of the K-rich cloud residues increased within southwesterly air masses from fire activities in Southeast Asia. When air masses changed from northerly polluted areas to southwesterly ocean and livestock areas, the amine particles increased from 0.2 to 15.1 % of the total cloud residues. The dust, Fe, Pb, Na-rich and OC particle types had a low contribution (0.5–4.1 %) to the total cloud residues. Higher fraction of nitrate (88–89 %) was found in the dust and Na-rich cloud residues relative to sulfate (41–42 %) and ammonium (15–23 %). Higher intensity of nitrate was found in the cloud residues relative to the ambient particles. Compared with nonactivated particles, nitrate intensity decreased in all cloud residues except for dust type. To our knowledge, this study is the first report on in situ observation of the chemical composition and mixing state of individual cloud residue particles in China.

Short summary
A ground-based counterflow virtual impactor coupled with a single-particle aerosol mass spectrometer (SPAMS) was used to assess the mixing state of individual cloud residue particles. Abundant aged EC cloud residues that internally mixed with inorganic salts were found in air masses from northerly polluted areas. K-rich cloud residues significantly increased within southwesterly air masses. This study increases our understanding of the impacts of aerosols on cloud droplets in southern China.
Altmetrics
Final-revised paper
Preprint