[1] Swedish Inst Space Phys, S-75121 Uppsala, Sweden
[2] Univ Alaska, Inst Geophys, Fairbanks, AK 99775 USA
[3] Univ London Imperial Coll Sci Technol & Med, Dept Phys, Space & Atmospher Phys Grp, London SW7 2BW, England
[4] Inst Pierre Simon Laplace, CNRS, Ctr Etude Environm Terrestre & Planetaires, F-78140 Velizy Villacoublay, France
[5] Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA
[6] Univ Kansas, Dept Phys & Astron, Lawrence, KS 66045 USA
[7] Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA
[8] Univ Michigan, Dept Atmospher Ocean & Space Sci, Ann Arbor, MI 48109 USA
[9] UCL, Mullard Space Sci Lab, Dorking RH5 6NT, Surrey, England
[10] SW Res Inst, San Antonio, TX 78238 USA