1. Department of Physics, Lund University, Professorsgatan 1, Lund SE-22363, Sweden
2. Swedish Meteorological and Hydrological Institute (SMHI), Norrköping SE-60176, Sweden
3. Institute for Atmospheric and Earth System Research (INAR)/Physics, Faculty of Science, University of Helsinki, P.O. Box 64, Helsinki 00014, Finland
4. Climate & Atmosphere Research Centre (CARE-C), The Cyprus Institute, P.O. Box 27456, Nicosia 1645, Cyprus
5. Institute for Atmospheric and Environmental Sciences, Goethe University Frankfurt, Frankfurt am Main 60438, Germany
6. Swedish Environmental Research Institute IVL, Malmö SE-21119, Sweden