1. Univ Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON, Villeurbanne 69626, France
2. Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, Helsinki 00014, Finland
3. Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, Villigen 5232, Switzerland
4. Center for Atmospheric Particle Studies, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
5. Department of Atmospheric Sciences, University of Washington, Seattle, Washington 98195, United States
6. Institute for Atmospheric and Environmental Sciences, Goethe University Frankfurt, Frankfurt am Main 60438, Germany
7. Institute for Ion Physics and Applied Physics, University of Innsbruck, Innsbruck 6020, Austria
8. Department of Chemistry & CIRES, University of Colorado Boulder, Boulder, Colorado 80309, United States
9. Helsinki Institute of Physics (HIP)/Physics, Faculty of Science, University of Helsinki, Helsinki 00014, Finland
10. Leibniz Institute for Tropospheric Research, Leipzig 04318, Germany
11. Institute of Physics, University of Tartu, Tartu 50090, Estonia
12. Aerodyne Research Inc., Billerica, Massachusetts 01821, United States
13. Finnish Meteorological Institute, Helsinki 00560, Finland
14. State Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Pollution Complex, Shanghai Academy of Environment Sciences, Shanghai 200233, P. R. China
15. Atmospheric and Oceanic Sciences, Princeton University, Princeton, New Jersey 08540, United States
16. CERN, the European Organization for Nuclear Research, Geneve 23 CH-1211, Switzerland
17. P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Moscow 119991, Russia
18. Department of Applied Physics, University of Eastern Finland, Kuopio 70211, Finland