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Hygroscopicity of aerosol particles and CCN activity of nearly hydrophobic particles in the urban atmosphere over Japan during summer
Author(s) -
Ogawa Shuhei,
Setoguchi Yoshitaka,
Kawana Kaori,
Nakayama Tomoki,
Ikeda Yuka,
Sawada Yuuki,
Matsumi Yutaka,
Mochida Michihiro
Publication year - 2016
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2015jd024636
Subject(s) - aerosol , cloud condensation nuclei , chemical composition , chemistry , sulfate , total organic carbon , fraction (chemistry) , deposition (geology) , hydrocarbon , analytical chemistry (journal) , mass spectrum , condensation , atmosphere (unit) , environmental chemistry , mass spectrometry , chromatography , organic chemistry , meteorology , physics , paleontology , sediment , biology
We investigated the hygroscopicity of 150 nm particles and the number‐size distributions and the cloud condensation nuclei (CCN) activity of nearly hydrophobic particles in aerosols over Nagoya, Japan, during summer. We analyzed the correlations between the number concentrations of particles in specific hygroscopic growth factor ( g ) ranges and the mass concentrations of chemical components. This analysis suggests the association of nearly hydrophobic particles with hydrocarbon‐like organic aerosol, elemental carbon and semivolatile oxygenated organic aerosol (SV‐OOA), that of less hygroscopic particles with SV‐OOA and nitrate and that of more hygroscopic particles with low‐volatile oxygenated organic aerosol (LV‐OOA) and sulfate. The hygroscopicity parameter ( κ ) of organics was derived based on the g distributions and chemical composition of 150 nm particles. The κ of the organics correlated positively with the fraction of the total organic mass spectral signal at m / z 44 and the volume fraction of the LV‐OOA to the organics, indicating that organics with highly oxygenated structures including carboxylic acid groups contribute to the water uptake. The number‐size distributions of the nearly hydrophobic particles with g around 1.0 and 1.1 correlated with the mass concentrations of chemical components. The results show that the chemical composition of the particles with g around 1.0 was different between the Aitken mode and the accumulation mode size ranges. An analysis for a parameter F max of the curves fitted to the CCN efficiency spectra of the particles with g around 1.0 suggests that the coating by organics associated with SV‐OOA elevated the CCN activity of these particles.