1. Department of Atmospheric and Oceanic Sciences; University of California; Los Angeles California USA
2. Solar-Terrestrial Environment Laboratory; Nagoya University; Nagoya Japan
3. Institute of Geophysics and Planetary Physics and Department of Earth and Space Sciences; University of California; Los Angeles California USA
4. Space Sciences Laboratory; University of California; Berkeley California USA
5. Laboratoire de Physique des Plasmas, UMR 7648; CNRS/Ecole Polytechnique/UPMC/Paris-Sud 11 Observatoire de Saint Maur; Saint-Maur-des-Fossés France