Earth and Planetary Science, Hokkaido University, Kita-ku, Sapporo, 060-0810 Japan; Space Environment Center, NOAA, 325 Broadway, Boulder, CO 80303, USA
Earth and Planetary Science, Hokkaido University, Kita-ku, Sapporo, 060-0810 Japan
Space Environment Center, NOAA, 325 Broadway, Boulder, CO 80303, USA