1. Institute for Atmospheric and Climate Science; ETH Zurich; Zurich Switzerland
2. Institute for Atmospheric Physics; Johannes-Gutenberg-University; Mainz Germany
3. Laboratory for Air Pollution and Environmental Technology; EMPA; Dübendorf Switzerland
4. Istituto di Scienze dell'Atmosfera e del Clima; Consiglio Nazionale delle Ricerche; Rome Italy
5. Jet Propulsion Laboratory; California Institute of Technology; Pasadena California USA
6. Consorzio Venezia Ricerche; Venice Italy
7. Centre Suisse d'Electronique et de Microtechnique SA (CSEM); Neuchatel Switzerland
8. Institute for Stratospheric Research; Forschungszentrum Jlich; Jlich Germany
9. Central Aerological Observatory; Moscow Russia
10. Particle Chemistry Department; Max-Planck-Institute for Chemistry; Mainz Germany