Japan Geoscience Union Meeting 2018

Presentation information

[EE] Oral

P (Space and Planetary Sciences) » P-EM Solar-Terrestrial Sciences, Space Electromagnetism & Space Environment

[P-EM15] Dynamics in magnetosphere and ionosphere

Mon. May 21, 2018 9:00 AM - 10:30 AM 303 (3F International Conference Hall, Makuhari Messe)

convener:Yoshimasa Tanaka(National Institute of Polar Research), Tomoaki Hori(Institute for Space-Earth Environmental Research, Nagoya University), Aoi Nakamizo(情報通信研究機構 電磁波研究所, 共同), Mitsunori Ozaki(Faculty of Electrical and Computer Engineering, Institute of Science and Engineering, Kanazawa University), Chairperson:Narita Yasuhito(Space Research Institute, Austrian Academy of Sciences)

10:15 AM - 10:30 AM

[PEM15-30] The spatial structure of magnetospheric plasma disturbance estimated by using magnetic data obtained by LEO satellites.

*Yoshihiro Yokoyama1, Toshihiko Iyemori2, Tadashi Aoyama (1.Department of Earth and Planetary Sciences, Graduate School of Science, Kyoto University, 2.Data Analysis Center for Geomagnetism and Space Magnetism Graduate School of Science, Kyoto University)

Keywords:Field-aligned current, Magnetosphere-ionosphere coupling, Swarm satellite

Field-aligned currents with various spatial scales flow into and out from high-latitude ionosphere. The magnetic fluctuations observed by LEO satellites along their orbits having period longer than a few seconds can be regarded as the manifestations of spatial structure of field aligned currents.This has been confirmed by using the initial orbital characteristics of 3 SWARM-satellites.
From spectral analysis, we evaluated the spectral indices of these magnetic fluctuations and investigated their dependence on regions, such as magnetic latitude and MLT and so on. We found that the spectral indices take quite different values between the regions lower than the equatorward boundary of the auroral oval (around 63 degrees’ in magnetic latitude) and the regions higher than that.
By the way, the FACs are believed to be generated in the magnetiospheric plasma sheet and boundary layer, and they flow along the field lines conserving their currents. Inaddition, the theory of FAC generation [e.g., Hasegawa and Sato ,1978] indicates that the FACs are strongly connected with magnetospheric plasma disturbances.
The spectral indices above are these of spatial structures of the FACs over the ionosphere, by using the theoretical equation of FAC generation, we can evaluate the spectral indices of magnetospheric plasma disturbance in FAC’s generation regions.
Furthermore, by projecting the area of fluctuations on the equatorial plane of magnetosphere (i.e. plasma sheet), we can estimate the spatial structure of magnetospheric plasma disturbance.
In this presentation, we will focus especially on magnetic flucutations of region1-FACs and show thire dependences on thire surrounding condition, such as the AE index and solar wind's parameters. We also discuss how to estimate the spectral indices of magnetospheric plasma.