1. NILU – Norsk Institutt for Luftforskning, Kjeller, Norway
2. Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
3. Climate System Research, Finnish Meteorological Institute, Helsinki, Finland
4. Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, Helsinki, Finland
5. European Commission Joint Research Centre, Ispra, Italy
6. Biogeochemistry and Modeling of the Earth System (BGEOSYS), Université Libre de Bruxelles, Brussels, Belgium