Articles | Volume 15, issue 21
Atmos. Chem. Phys., 15, 12211–12229, 2015

Special issue: BACCHUS – Impact of Biogenic versus Anthropogenic emissions...

Atmos. Chem. Phys., 15, 12211–12229, 2015

Research article 04 Nov 2015

Research article | 04 Nov 2015

A synthesis of cloud condensation nuclei counter (CCNC) measurements within the EUCAARI network

M. Paramonov1,a, V.-M. Kerminen1, M. Gysel2, P. P. Aalto1, M. O. Andreae3, E. Asmi4, U. Baltensperger2, A. Bougiatioti5, D. Brus4,6, G. P. Frank7, N. Good8,b, S. S. Gunthe3,c, L. Hao9, M. Irwin8,d, A. Jaatinen9, Z. Jurányi2,e, S. M. King10,f, A. Kortelainen9, A. Kristensson7, H. Lihavainen4, M. Kulmala1, U. Lohmann11, S. T. Martin10, G. McFiggans8, N. Mihalopoulos5, A. Nenes12,13,14, C. D. O'Dowd15, J. Ovadnevaite15, T. Petäjä1, U. Pöschl3, G. C. Roberts16,17, D. Rose3,g, B. Svenningsson7, E. Swietlicki7, E. Weingartner2,e, J. Whitehead8, A. Wiedensohler18, C. Wittbom7, and B. Sierau11 M. Paramonov et al.
  • 1Department of Physics, University of Helsinki, P.O. Box 64, 00014 Helsinki, Finland
  • 2Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
  • 3Biogeochemistry and Multiphase Chemistry Departments, Max Planck Institute for Chemistry, Mainz, Germany
  • 4Finnish Meteorological Institute, Erik Palménin aukio 1, P.O. Box 503, 00101 Helsinki, Finland
  • 5Environmental Chemical Processes Laboratory, University of Crete, Heraklion, Greece
  • 6Laboratory of Aerosols Chemistry and Physics, Institute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, Rozvojová 135, 165 02 Prague 6, Czech Republic
  • 7Division of Nuclear Physics, Department of Physics, Lund University, P.O. Box 118, 22100 Lund, Sweden
  • 8Centre for Atmospheric Science, SEAES, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
  • 9Department of Applied Physics, University of Eastern Finland, 70210 Kuopio, Finland
  • 10School of Engineering and Applied Sciences and Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, USA
  • 11Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
  • 12School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
  • 13School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
  • 14Institute of Chemical Engineering Sciences (ICE-HT), FORTH, Patras, Greece
  • 15School of Physics and Centre for Climate and Air Pollution Studies, Ryan Institute, National University of Ireland Galway, University Road, Galway, Ireland
  • 16Centre National de Recherches Météorologiques, Toulouse, France
  • 17Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA
  • 18Leibniz Institute for Tropospheric Research, Leipzig, Germany
  • anow at: Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
  • bnow at: Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA
  • cnow at: Department of Civil Engineering, Indian Institute of Technology Madras, Chennai, India
  • dnow at: Cambustion Ltd., Cambridge, UK
  • enow at: Institute of Aerosol and Sensor Technology, University of Applied Sciences Northwestern Switzerland, Windisch, Switzerland
  • fnow at: Haldor Topsøe A/S, Copenhagen, Denmark
  • gnow at: Institute for Atmospheric and Environmental Sciences, Goethe-University Frankfurt am Main, Frankfurt am Main, Germany

Abstract. Cloud condensation nuclei counter (CCNC) measurements performed at 14 locations around the world within the European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) framework have been analysed and discussed with respect to the cloud condensation nuclei (CCN) activation and hygroscopic properties of the atmospheric aerosol. The annual mean ratio of activated cloud condensation nuclei (NCCN) to the total number concentration of particles (NCN), known as the activated fraction A, shows a similar functional dependence on supersaturation S at many locations – exceptions to this being certain marine locations, a free troposphere site and background sites in south-west Germany and northern Finland. The use of total number concentration of particles above 50 and 100 nm diameter when calculating the activated fractions (A50 and A100, respectively) renders a much more stable dependence of A on S; A50 and A100 also reveal the effect of the size distribution on CCN activation. With respect to chemical composition, it was found that the hygroscopicity of aerosol particles as a function of size differs among locations. The hygroscopicity parameter κ decreased with an increasing size at a continental site in south-west Germany and fluctuated without any particular size dependence across the observed size range in the remote tropical North Atlantic and rural central Hungary. At all other locations κ increased with size. In fact, in Hyytiälä, Vavihill, Jungfraujoch and Pallas the difference in hygroscopicity between Aitken and accumulation mode aerosol was statistically significant at the 5 % significance level. In a boreal environment the assumption of a size-independent κ can lead to a potentially substantial overestimation of NCCN at S levels above 0.6 %. The same is true for other locations where κ was found to increase with size. While detailed information about aerosol hygroscopicity can significantly improve the prediction of NCCN, total aerosol number concentration and aerosol size distribution remain more important parameters. The seasonal and diurnal patterns of CCN activation and hygroscopic properties vary among three long-term locations, highlighting the spatial and temporal variability of potential aerosol–cloud interactions in various environments.

Short summary
The research paper presents the first comprehensive overview of field measurements with the CCN Counter performed at a large number of locations around the world within the EUCAARI framework. The paper sheds light on the CCN number concentrations and activated fractions around the world and their dependence on the water vapour supersaturation ratio, the dependence of aerosol hygroscopicity on particle size, and seasonal and diurnal variation of CCN activation and hygroscopic properties.
Final-revised paper