1. Laboratoire des Sciences du Climat et de l’Environnement (LSCE/IPSL), CEA-CNRS-UVSQ, 91191 Gif sur Yvette, France
2. Finnish Meteorological Institute, Air Quality Research, Sahaajankatu 20E, 00880 Helsinki, Finland
3. Centro Elettrotecnico Sperimentale Italiano, Via Rubattino 54–20134 Milano, Italy
4. National Oceanic and Atmospheric Administration, Earth System Research Laboratory, 325 Broadway, Boulder, CO 80305, USA
5. Hungarian Meteorological Service, H-1675 Budapest, P.O. Box 39, Hungary
6. Umweltbundesamt, Postfach 1229, 79196 Kirchzarten, Germany
7. School of Chemistry, University of Bristol, Bristol, Uk
8. AGH University of Science and Technology, Krakow, Poland