Atmos. Chem. Phys. Discuss., 7, 7819-7841, 2007
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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.
The role of VOC oxidation products in continental new particle formation
A. Laaksonen1,4, M. Kulmala2, C. D. O'Dowd3, J. Joutsensaari1,*, P. Vaattovaara1, S. Mikkonen1, K. E. J. Lehtinen1,4, L. Sogacheva2, M. Dal Maso2, P. Aalto2, T. Petäjä2, A. Sogachev2, Y. Jun Yoon3,**, H. Lihavainen4, D. Nilsson5, M. Cristina Facchini6, F. Cavalli6,***, S. Fuzzi6, T. Hoffmann7, F. Arnold8, M. Hanke8, K. Sellegri8,****, B. Umann8, W. Junkermann9, H. Coe10, J. D. Allan10, M. Rami Alfarra10,*****, D. R. Worsnop11, M.-L. Riekkola12, T. Hyötyläinen12, and Y. Viisanen4
1University of Kuopio, Department of Physics, P.O. Box 1627, 70211 Kuopio, Finland
2University of Helsinki, Department of Physical Sciences, Helsinki, Finland
3National University of Ireland, Galway, Department of Physics
4Finnish Meteorological Institute, P.O. Box 503, 00101 Helsinki, Finland
5Stockholm University, Department of Applied Environmental Science (ITM), Atmospheric Science Unit, 10691, Stockholm, Sweden
6Istituto di Scienze dell'Atmosfera e del Clima – CNR, Italy Via Gobetti 101, 40 129 Bologna, Italy
7Johannes Gutenberg-University of Mainz, 55128, Mainz, Germany
8Max-Planck-Institute for Nuclear Physics, Heidelberg, Germany
9Forschungszentrum Karlsruhe, Institute for Meteorology and Climate Research, IMK-IFU, Garmisch-Partenkirchen, Germany
10School of Atmospheric and Environmental Science, University of Manchester, P.O. Box 88, Manchester, M60 1QD, UK
11Aerodyne Research Inc., 45 Manning Road, Billerica, Ma 01821-3976, USA
12University of Helsinki, Department of Chemistry, Helsinki, Finland
*now at: University of Kuopio, Department of Environmental Sciences, P.O. Box 1627, 70211 Kuopio, Finland
**now at: Korea Polar Research Institute, SongDo Techno Park, 7–50, Songdo-dong, Yeonsu-Gu, Incheon City 406-840, Korea
***now at: Joint Research Centre, Via E. Fermi, 1, 21020 Ispra, Italy
****now at: Laboratoire de Météorologie Physique (LaMP), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), UMR 6016 CNRS, France
*****now at: Paul Scherrer Institut, 5232 Villigen, Switzerland

Abstract. Aerosol physical and chemical properties and trace gas concentrations were measured during the QUEST field campaign in March–April, 2003, in Hyytiälä, Finland. Our aim was to understand the role of oxidation products of VOC's such as mono- and sesquiterpenes in atmospheric nucleation events. Particle chemical compositions were measured using the Aerodyne Aerosol Mass Spectrometer, and chemical compositions of aerosol samples collected with low-pressure impactors and a high volume sampler were analysed using a number of techniques. The results indicate that during and after new particle formation, all particles larger than 50 nm in diameter contained similar organic substances that are likely to be mono- and sesquiterpene oxidation products. The oxidation products identified in the high volume samples were shown to be mostly aldehydes. In order to study the composition of particles in the 10–50 nm range, we made use of Tandem Differential Mobility Analyzer results. We found that during nucleation events, both 10 and 50 nm particle growth factors due to uptake of ethanol vapour correlate strongly with gas-phase monoterpene oxidation product (MTOP) concentrations, indicating that the organic constituents of particles smaller than 50 nm in diameter are at least partly similar to those of larger particles. We furthermore showed that particle growth rates during the nucleation events are correlated with the gas-phase MTOP concentrations. This indicates that VOC oxidation products may have a key role in determining the spatial and temporal features of the nucleation events. This conclusion was supported by our aircraft measurements of new 3–10 nm particle concentrations, which showed that the nucleation event on 28 March 2003, started at the ground layer, i.e. near the VOC source, and evolved together with the mixed layer. Furthermore, no new particle formation was detected upwind away from the forest, above the frozen Gulf of Bothnia.

Citation: Laaksonen, A., Kulmala, M., O'Dowd, C. D., Joutsensaari, J., Vaattovaara, P., Mikkonen, S., Lehtinen, K. E. J., Sogacheva, L., Dal Maso, M., Aalto, P., Petäjä, T., Sogachev, A., Jun Yoon, Y., Lihavainen, H., Nilsson, D., Cristina Facchini, M., Cavalli, F., Fuzzi, S., Hoffmann, T., Arnold, F., Hanke, M., Sellegri, K., Umann, B., Junkermann, W., Coe, H., Allan, J. D., Rami Alfarra, M., Worsnop, D. R., Riekkola, M.-L., Hyötyläinen, T., and Viisanen, Y.: The role of VOC oxidation products in continental new particle formation, Atmos. Chem. Phys. Discuss., 7, 7819-7841, doi:10.5194/acpd-7-7819-2007, 2007.
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