1. Space and Upper Atmospheric Sciences Group; National Institute of Polar Research; Tachikawa Japan
2. Department of Polar Science, School of Multidisciplinary Sciences; SOKENDAI (Graduate University for Advanced Studies); Tachikawa Japan
3. Research Institute for Science and Engineering; Waseda University; Shinjuku Japan
4. Department of Physics; Waseda University; Shinjuku Japan
5. Institute for Cosmic Ray Research; University of Tokyo; Kashiwa Japan
6. Institute of Physics; Kanagawa University; Yokohama Japan
7. Department of Physical Sciences; Ritsumeikan University; Kusatsu Japan