1. Graduate School of Communication Engineering and InformaticsThe University of Electro‐Communications Chofu Japan
2. National Institute of Polar Research Tachikawa Japan
3. Department of Polar Science, School of Multidisciplinary Sciences, SOKENDAIThe Graduate University for Advanced Studies Tachikawa Japan
4. Institute for Space‐Earth Environmental ResearchNagoya University Nagoya Japan
5. Ionospheric Physics Research UnitUniversity of Oulu Oulu Finland
6. Graduate School of Natural Science and TechnologyKanazawa University Kanazawa Japan