[P-EM12] Dynamics of the Inner Magnetospheric System

[PEM12-15] Statistical characteristics of the magnetic field variations observed by Arase

*松岡 彩子¹、能勢 正仁²、三好 由純²、寺本 万里子⁴、野村 麗子³、藤本 晶子⁵、田中 良昌⁶、篠原 学⁷、栗田 怜⁸、今城 峻²、篠原 育³ (1.京都大学 理学研究科 地磁気世界資料解析センター、2.名古屋大学　宇宙地球環境研究所、3.宇宙航空研究開発機構　宇宙科学研究所、4.九州工業大学 大学院工学研究院、5.九州工業大学 情報工学部、6.国立極地研究所、7.鹿児島工業高等専門学校、8.京都大学 生存圏研究所)

キーワード：磁場擾乱、放射線帯、内部磁気圏

We are investigating the magnetic field variations in association with the relativistic electrons in the inner magnetosphere. The magnetospheric disturbance phenomena, e.g., dipolarization and bursty bulk flow from the night-side plasma sheet, are often accompanied by the broadband magnetic field variation. The variation between a few Hz and a few tens Hz has the potential for factor of the rapid increase of the relativistic electrons in the inner magnetosphere.
The magnetic field variations in those frequencies are measured by MGF, fluxgate magnetometer, onboard the Arase satellite. We have investigated the magnetic disturbance in the outer radiation belt; intensity, spatial distribution, occurrence probability and polarization are statistically analyzed. In the overview, large-amplitude magnetic variations often appear in accordance with the substorm and dipolarization phenomena in the pre-midnight sencor and the EMIC waves in the afternoon sector. The amplitude in the xy plane in the SM coordinate overwhelm and therefore indicate the transverse polarization characteristics. It should be examined in detail in the reference frame to the background field.
We are extending our study to the spectral characteristics associated with the local proton (and other ions) cyclotron frequency, dependence on the magnetic activity and solar-wind condition.