1. Department of Physics and Astronomy West Virginia University Morgantown WV USA
2. Space Sciences Laboratory University of California Berkeley CA USA
3. Department of Physics and Astronomy University of Iowa Iowa City IA USA
4. Laboratory of Atmospheric and Space Physics University of Colorado Boulder CO USA
5. IRAP CNRS UPS CNES University of Toulouse Toulouse France
6. NASA Goddard Space Flight Center Greenbelt MD USA