Publication Date:
2016-04-29
Description:
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 and elemental carbon and semi-volatile 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 ( k ) of organics was derived based on the g distributions and chemical composition of 150 nm particles. The k 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.
Print ISSN:
0148-0227
Topics:
Geosciences
,
Physics
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