*関 華奈子¹、原 拓也²、Dave Brain³、Christopher Fowler⁴、James McFadden²、Jasper Halekas⁵、DiBraccio Gina⁶ (1.東京大学大学院理学系研究科、2.Space Science Laboratory, University of California, Berkeley, USA、3.LASP, University of Colorado Boulder, USA、4.Department of Physics and Astronomy, West Virginia University, USA、5.Department of Physics and Astronomy, University of Iowa, USA、6.NASA Goddard Space Flight Center, USA)