Semi-empirical parameterization of size-dependent atmospheric nanoparticle growth in continental environments
2013 (English)In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 13, no 15, 7665-7682 p.Article in journal (Refereed) Published
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-20 nm 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 (SORG(MT)) and an additional condensable vapor of non-monoterpene organics (background). The performance of the proposed parameterization was investigated using ambient data on particle growth rates in three diameter ranges (1.5-3 nm, 3-7 nm and 7-20 nm). The growth rate data were acquired from particle / air ion number size distribution measurements at six continental sites over Europe. The longest time series of 7 yr (2003-2009) was obtained from a boreal forest site in Hyytiala, 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-20 nm particle growth and to determine the weighing factors for distributing the SORG(MT) 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 6x10(7) cm(-3) (consistent with an additional global SOA yield of 100 Tg yr(-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.
Place, publisher, year, edition, pages
2013. Vol. 13, no 15, 7665-7682 p.
Meteorology and Atmospheric Sciences
IdentifiersURN: urn:nbn:se:su:diva-93595DOI: 10.5194/acp-13-7665-2013ISI: 000323103900025OAI: oai:DiVA.org:su-93595DiVA: diva2:647041
University of Helsinki 490082; Maj and Tor Nessling Foundation 2010143; Academy of Finland 139656; Finnish Center of Excellence grant 1118615; European Research Council grant ATMNUCLE 227463; European Research Council grant ATMOGAIN 278277; European Integrated project PEGASOS FP7-ENV-2010-265148; Finnish Academy of Science and Letters (Vilho, Yrjö and Kalle Vaisala Foundation) 2013-09-102013-09-102013-09-10Bibliographically approved