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- Title
Semi-empirical parameterization of size-dependent atmospheric nanoparticle growth in continental environments.
- Authors
Häkkinen, S. A. K.; Manninen, H. E.; Yli-Juuti, T.; Merikanto, J.; Kajos, M. K.; Nieminen, T.; D'Andrea, S. D.; Asmi, A.; Pierce, J. R.; Kulmala, M.; Riipinen, I.
- Abstract
The capability to accurately yet efficiently represent atmospheric nanoparticle growth by biogenic and anthropogenic secondary organics is a challenge for current atmospheric large-scale models. It is, however, crucial to predict nanoparticle growth accurately in order to reliably estimate the atmospheric cloud condensation nuclei (CCN) concentrations. In this work we introduce a simple semi-empirical parameterization for sub-20nm particle growth that distributes secondary organics to the nanoparticles according to their size and is therefore able to reproduce particle growth observed in the atmosphere. The parameterization includes particle growth by sulfuric acid, secondary organics from monoterpene oxidation (SORGMT) and an additional condensable nonmonoterpene organics ("background"). The performance of the proposed parameterization was investigated using ambient data on particle growth rates in three size ranges (1.5-3 nm, 3-7nm and 7-20 nm). The growth rate data was acquired from particle/air ion number size distribution measurements at six continental sites over Europe. The longest time series of 7 yr (2003 to 2009) was obtained from a boreal forest site in Hyytiälä, Finland, while about one year of data (2008-2009) was used for the other stations. The extensive ambient measurements made it possible to test how well the parameterization captures the seasonal cycle observed in sub-20nm particle growth and to determine the weighing factors for distributing the SORGMT for different sized particles as well as the background mass flux (/concentration). Besides the monoterpene oxidation products, background organics with a concentration comparable to SORGMT, around 6x107 cm-3 (consistent with an additional global SOA yield of 100 Tgyr-1) was needed to reproduce the observed nanoparticle growth. Simulations with global models suggest that the "background" could be linked to secondary biogenic organics that are formed in the presence of anthropogenic pollution.
- Subjects
AIR pollution; EMPIRICAL research; NANOPARTICLES; CRYSTAL growth; PARAMETERIZATION; MONOTERPENES; CONDENSATION (Meteorology); CLOUDS
- Publication
Atmospheric Chemistry & Physics Discussions, 2013, Vol 13, Issue 3, p8489
- ISSN
1680-7367
- Publication type
Article
- DOI
10.5194/acpd-13-8489-2013