1. Department of Physics University of Helsinki Helsinki Finland
2. Space Research Institute Austrian Academy of Sciences Graz Austria
3. Directorate of Science European Space Research and Technology Centre (ESA/ESTEC) Noordwijk The Netherlands
4. School of Physics and Astronomy Queen Mary University of London London UK
5. Finnish Meteorological Institute Helsinki Finland
6. IRAP, Université de Toulouse/CNRS/UPS/CNES Toulouse France