1. Department of Information and Communication EngineeringUniversity of Electro‐Communications Tokyo Japan
2. Graduate School of ScienceKyoto University Kyoto Japan
3. Planetary Plasma and Atmospheric Research CenterTohoku University Sendai Japan
4. Institute of Space and Astronautical ScienceJapan Aerospace Exploration Agency Sagamihara Japan
5. National Institute of Polar Research Tokyo Japan