[P-EM12] Dynamics of the Inner Magnetospheric System

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

*Ayako Matsuoka¹, Masahito Nose², Yoshizumi Miyoshi², Mariko Teramoto⁴, Reiko Nomura³, Akiko Fujimoto⁵, Yoshimasa Tanaka⁶, Manabu Shinohara⁷, Satoshi Kurita⁸, Shun Imajo², Iku Shinohara³ (1.Data Analysis Center for Geomagnetism and Space Magnetism, Graduate School of Science, Kyoto University, 2.Institute for Space-Earth Environmental Research, Nagoya University, 3.Institute of Space and Astronautical Science, JAXA, 4.Graduate School of Engineering, Kyushu Institute of Technology, 5.Graduate School of Computer Science and Systems Engineering, Kyushu Institute of Technology, 6.National Institute of Polar Research, 7.National Institute of Technology Kagoshima College, 8.Research Institute for Sustainable Humanosphere, Kyoto University)

Keywords:magnetic field disturbance, radiation belt, inner magnetosphere

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.