Articles | Volume 10, issue 22
Atmos. Chem. Phys., 10, 10829–10848, 2010

Special issue: European Integrated Project on Aerosol-Cloud-Climate and Air...

Atmos. Chem. Phys., 10, 10829–10848, 2010

Research article 18 Nov 2010

Research article | 18 Nov 2010

Atmospheric nucleation: highlights of the EUCAARI project and future directions

V.-M. Kerminen1,2, T. Petäjä1, H. E. Manninen1, P. Paasonen1, T. Nieminen1, M. Sipilä1, H. Junninen1, M. Ehn1, S. Gagné1, L. Laakso1,12, I. Riipinen1,13, H. Vehkamäki1, T. Kurten1, I. K. Ortega1, M. Dal Maso1,6, D. Brus2, A. Hyvärinen2, H. Lihavainen2, J. Leppä2, K. E. J. Lehtinen2,11, A. Mirme3, S. Mirme3, U. Hõrrak3, T. Berndt4, F. Stratmann4, W. Birmili4, A. Wiedensohler4, A. Metzger5,*, J. Dommen5, U. Baltensperger5, A. Kiendler-Scharr6, T. F. Mentel6, J. Wildt6, P. M. Winkler7,**, P. E. Wagner7, A. Petzold8, A. Minikin8, C. Plass-Dülmer9, U. Pöschl10, A. Laaksonen1,11, and M. Kulmala1 V.-M. Kerminen et al.
  • 1Department of Physics, P.O. Box 64, 00014 University of Helsinki, Finland
  • 2Finnish Meteorological Institute, Research and Development, P.O. Box 503, 00101 Helsinki, Finland
  • 3Institute of Physics, University of Tartu, Ülikooli 18, 50090, Tartu, Estonia
  • 4Leibniz-nstitute für Troposphärenforschung, Permoserstrasse 15, Leipzig 04318, Germany
  • 5Laboratory of Atmospheric Chemistry, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
  • 6Institut für Chemie und Dynamik der Geosphäre (ICG), Forschungszentrum Jülich, 52425 Jülich, Germany
  • 7Fakultät für Physik, Universität Wien, Boltzmanngasse 5, 1090 Wien, Austria
  • 8Deutsches Zentrum für Luft- und Raumfarhr, Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany
  • 9Hohenpeissenberg Meteorological Observatory, Deutscher Wetterdienst, Germany
  • 10Max Planck Institute for Chemistry, Biogeochemistry Department, P.O. Box 3060, 55128 Mainz, Germany
  • 11Department of Physics and Mathematics, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland
  • 12School of Physical and Chemical Sciences, North-West University, Potchefstroom, South Africa
  • 13Department of Chemical Engineering, Carnegie Mellon University, 15213, Pittsburgh, PA, USA
  • *now at: Ionicon Analytik GmbH, 6020 Innsbruck, Austria
  • **now at: Atmospheric Chemistry Division, National Center for Atmospheric Research, 1850 Table Mesa Dr., Boulder, CO-80305, USA

Abstract. Within the project EUCAARI (European Integrated project on Aerosol Cloud Climate and Air Quality interactions), atmospheric nucleation was studied by (i) developing and testing new air ion and cluster spectrometers, (ii) conducting homogeneous nucleation experiments for sulphate and organic systems in the laboratory, (iii) investigating atmospheric nucleation mechanism under field conditions, and (iv) applying new theoretical and modelling tools for data interpretation and development of parameterisations. The current paper provides a synthesis of the obtained results and identifies the remaining major knowledge gaps related to atmospheric nucleation. The most important technical achievement of the project was the development of new instruments for measuring sub-3 nm particle populations, along with the extensive application of these instruments in both the laboratory and the field. All the results obtained during EUCAARI indicate that sulphuric acid plays a central role in atmospheric nucleation. However, also vapours other than sulphuric acid are needed to explain the nucleation and the subsequent growth processes, at least in continental boundary layers. Candidate vapours in this respect are some organic compounds, ammonia, and especially amines. Both our field and laboratory data demonstrate that the nucleation rate scales to the first or second power of the nucleating vapour concentration(s). This agrees with the few earlier field observations, but is in stark contrast with classical thermodynamic nucleation theories. The average formation rates of 2-nm particles were found to vary by almost two orders of magnitude between the different EUCAARI sites, whereas the formation rates of charged 2-nm particles varied very little between the sites. Overall, our observations are indicative of frequent, yet moderate, ion-induced nucleation usually outweighed by much stronger neutral nucleation events in the continental lower troposphere. The most concrete outcome of the EUCAARI nucleation studies are the new semi-empirical nucleation rate parameterizations based on field observations, along with updated aerosol formation parameterizations.

Final-revised paper