1. Max‐Planck‐Institute for Solar System Research Göttingen Germany
2. Rheinisches Institut fuer Umweltforschung Abteilung Planetforschung Cologne Germany
3. Space Sciences Laboratory U.C. Berkeley Berkeley CA USA
4. Department of Physics and Astronomy University of Iowa Iowa City IA USA
5. NASA Goddard Space Flight Center Maryland USA
6. Laboratory for Atmospheric and Space Physics University of Colorado Boulder CO USA
7. Institute of Space Research Moscow Russia