Atmos. Chem. Phys. Discuss., 12, 11415-11443, 2012
www.atmos-chem-phys-discuss.net/12/11415/2012/
doi:10.5194/acpd-12-11415-2012
© Author(s) 2012. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Particle hygroscopicity during atmospheric new particle formation events: implications for the chemical species contributing to particle growth
Z. Wu, W. Birmili, L. Poulain, M. Merkel, B. Fahlbusch, D. van Pinxteren, H. Herrmann, and A. Wiedensohler
Leibniz Institute for Tropospheric Research, Permoserstraße 15, 04318 Leipzig, Germany

Abstract. This study examines the hygroscopicity of newly formed particles (smaller than 50 nm in particle mobility diameter) during two atmospheric new particle formation events with and without clear growth process at mid-level mountain range in Central Germany based on HCCT field campaign. Particle hygroscopicity measurements show that the particle soluble fractions at the end of event for two events are, respectively 60% (45 nm particles for the event with clear growth) and 20% (30 nm particles for the event without clear growth), stressing that non-soluble organic compounds may play a key role in particle growth during new particle formation event. Such significant difference in particle hygroscopicity also suggests that the chemical species responsible for nucleation particle growth are considerably different between the two selected NPF events. During both events, the hygroscopicity of newly formed particles decreased with particle growth, indicating that more less-hygroscopic compounds contribute to the subsequent condensation in contrast to the earlier stage. Sulfuric acid was considered to be responsible of the NPF event and represent the highly hygroscopic compounds. However, calculation demonstrated that sulfuric acid condensation failed to fully explain the observed soluble fraction in the nucleation mode particles. Therefore, we hypothesize that some water-soluble matters may explain the missing soluble fraction.

Citation: Wu, Z., Birmili, W., Poulain, L., Merkel, M., Fahlbusch, B., van Pinxteren, D., Herrmann, H., and Wiedensohler, A.: Particle hygroscopicity during atmospheric new particle formation events: implications for the chemical species contributing to particle growth, Atmos. Chem. Phys. Discuss., 12, 11415-11443, doi:10.5194/acpd-12-11415-2012, 2012.
 
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