1. Institute for Atmospheric and Environmental Sciences Goethe University Frankfurt Frankfurt am Main Germany
2. Laboratory of Atmospheric Chemistry Paul Scherrer Institute Villigen Switzerland
3. Institute of Atmospheric and Climate Science ETH Zurich Zurich Switzerland
4. Department of Physics University of Helsinki Helsinki Finland
5. Physics Department CERN Geneva Switzerland
6. School of Earth and Environment University of Leeds Leeds UK
7. Atmospheric Research Centre of Eastern Finland Finnish Meteorological Institute Kuopio Finland
8. Cooperative Institute for Research in Environmental Sciences University of Colorado Boulder Boulder Colorado USA
9. Institute for Ion and Applied Physics University of Innsbruck Innsbruck Austria
10. Ionicon Analytik GmbH Innsbruck Austria
11. Center for Atmospheric Particle Studies Carnegie Mellon University Pittsburgh Pennsylvania USA
12. Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena California USA
13. Department of Applied Physics University of Eastern Finland Kuopio Finland
14. Faculty of Physics University of Vienna Vienna Austria
15. Solar and Cosmic Ray Research Laboratory Lebedev Physical Institute Moscow Russia
16. Onera‐The French Aerospace Lab Palaiseau France
17. Finnish Meteorological Institute Helsinki Finland
18. Department of Atmospheric Sciences University of Washington Seattle Washington USA
19. Department of Chemistry University of California Irvine California USA
20. SIM University of Lisbon and University of Beira Interior Lisbon Portugal
21. Leibniz Institute for Tropospheric Research Leipzig Germany