1. Earth, Planetary, and Space Sciences; University of California; Los Angeles California USA
2. Institute of Geophysics and Planetary Physics; University of California; Los Angeles California USA
3. Los Alamos National Laboratory; Los Alamos New Mexico USA
4. Institute of Geophysics and Meteorology; University of Cologne; Germany
5. Space and Atmospheric Physics Group; The Blackett Laboratory, Imperial College; London UK