1. Extreme Environments Research Laboratory École Polytechnique Fédérale de Lausanne Lausanne Switzerland
2. Laboratory of Atmospheric Chemistry Paul Scherrer Institute Villigen PSI Switzerland
3. Institute for Atmospheric and Earth System Research/Physics University of Helsinki Helsinki Finland
4. Finnish Meteorological Institute Helsinki Finland
5. Institute for Tropospheric Research Experimental Aerosol and Cloud Microphysics Leipzig Germany