Department of Geophysics, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakechou, Sakyou-ku, Kyoto, 606-8502, Japan
Data Analysis Center for Geomagnetism and Space Magnetism Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakechou, Sakyou-ku, Kyoto, 606-8502, Japan
Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723-6099, USA
Hermanus Magnetic Observatory, Hermanus, South Africa, P. O. Box 32 Hermanus 7200, Republic of South Africa, Hermanus, 7200, South Africa; School of Physics, University of KwaZulu-Natal, South Africa, School of Pure and Applied Physics, University of KwaZulu-Natal, Durban, 4041, South Africa