1. Institute for Atmospheric and Earth System Research, University of Helsinki, Helsinki, Finland
2. Swedish Meteorological and Hydrological Institute, Norrköping, Sweden
3. Laboratory of Atmospheric Chemistry, Paul Scherrer Institute, Villigen, Switzerland
4. Institute for Atmospheric and Environmental Sciences, Goethe University Frankfurt, Frankfurt am Main, Germany
5. Finnish Meteorological Institute, Helsinki, Finland
6. Department of Environmental Science (ACES), Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden