Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 16, 5545-5560, 2016
https://doi.org/10.5194/acp-16-5545-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
04 May 2016
Growth of atmospheric clusters involving cluster–cluster collisions: comparison of different growth rate methods
Jenni Kontkanen1, Tinja Olenius2, Katrianne Lehtipalo1,3, Hanna Vehkamäki1, Markku Kulmala1, and Kari E. J. Lehtinen4,5 1Department of Physics, University of Helsinki, 00014 Helsinki, Finland
2Department of Environmental Science and Analytical Chemistry (ACES) and Bolin Centre for Climate Research, Stockholm University, 10691 Stockholm, Sweden
3Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
4Finnish Meteorological Institute, 70211 Kuopio, Finland
5Department of Applied Physics, University of Eastern Finland, 70211 Kuopio, Finland
Abstract. We simulated the time evolution of atmospheric cluster concentrations in a one-component system where not only do clusters grow by condensation of monomers, but cluster–cluster collisions also significantly contribute to the growth of the clusters. Our aim was to investigate the consistency of the growth rates of sub-3 nm clusters determined with different methods and the validity of the common approach to use them to estimate particle formation rates. We compared the growth rate corresponding to particle fluxes (FGR), the growth rate derived from the appearance times of clusters (AGR), and the growth rate calculated based on irreversible vapor condensation (CGR). We found that the relation between the different growth rates depends strongly on the external conditions and the properties of the model substance. The difference between the different growth rates was typically highest at the smallest, sub-2 nm sizes. FGR was generally lower than AGR and CGR; at the smallest sizes the difference was often very large, while at sizes larger than 2 nm the growth rates were closer to each other. AGR and CGR were in most cases close to each other at all sizes. The difference between the growth rates was generally lower in conditions where cluster concentrations were high, and evaporation and other losses were thus less significant. Furthermore, our results show that the conventional method used to determine particle formation rates from growth rates may give estimates far from the true values. Thus, care must be taken not only in how the growth rate is determined but also in how it is applied.

Citation: Kontkanen, J., Olenius, T., Lehtipalo, K., Vehkamäki, H., Kulmala, M., and Lehtinen, K. E. J.: Growth of atmospheric clusters involving cluster–cluster collisions: comparison of different growth rate methods, Atmos. Chem. Phys., 16, 5545-5560, https://doi.org/10.5194/acp-16-5545-2016, 2016.
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