1. Department of Physics and Astronomy University of Iowa Iowa City IA USA
2. Space Sciences Laboratory University of California, Berkeley Berkeley CA USA
3. NASA Goddard Space Flight Center Greenbelt MD USA
4. Technical University of Braunschweig Braunschweig Germany
5. Department of Geophysics Graduate School of Science Kyoto University Kyoto Japan
6. Los Alamos National Laboratory Los Alamos NM USA