1. Department of Atmospheric and Oceanic Sciences; University of California, Los Angeles; Los Angeles California USA
2. Department of Earth and Space Sciences; University of California, Los Angeles; Los Angeles California USA
3. Department of Physics and Astronomy; University of Calgary; Calgary Alberta Canada
4. Space Science Laboratory; University of California, Berkeley; Berkeley California USA
5. Institut für Geophysik und extraterrestrische Physik; Technischen Universität Braunschweig; Braunschweig Germany