[1] Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA
[2] Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA
[3] Russian Acad Sci, Space Res Inst, Moscow, Russia
[4] New Jersey Inst Technol, Newark, NJ USA
[5] Univ Calif Los Angeles, Inst Geophys & Planetary Sci, Los Angeles, CA USA
[6] Swedish Inst Space Phys, Uppsala, Sweden
[7] Uppsala Univ, Dept Phys & Astron, Space & Plasma Phys, Uppsala, Sweden
[8] Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA
[9] NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA
[10] Royal Inst Technol, Stockholm, Sweden