Grant-in-Aid for Scientific Research (B).
Space and upper atmospheric physics
|Research Institution||KYUSHU UNIVERSITY|
YUMOTO Kiyohumi Kyushu University, Faculty of Sciences Professor, 大学院・理学研究院, 教授 (20125686)
菊池 崇 独立行政法人, 通信総合研究所, 上席研究官
田中 義人 山口大学, 教育学部, 教授 (30023675)
ITONAGA Masahiro Yamaguchi University Faculty of Education Professor, 教育学部, 教授 (60213104)
立原 裕司 九州大学, 大学院・理学研究科, 助手 (00227092)
KAWANO Hideaki Kyushu University, Faculty of Sciences, Associate Professor, 大学院・理学研究院, 助教授 (60304721)
YOSHIKAWA Akimasa Kyushu University Faculty of Sciences Research Associate, 大学院・理学研究院, 助手 (70284479)
IIJIMA Takeshi Kyushu University, Faculty of Sciences, Professor, 大学院・理学研究院, 教授 (70011624)
KIKUCHI Takashi Communication Research Laboratory Chief Researcher
|Project Fiscal Year
1998 – 2001
Completed(Fiscal Year 2001)
|Budget Amount *help
¥12,600,000 (Direct Cost : ¥12,600,000)
Fiscal Year 2001 : ¥3,600,000 (Direct Cost : ¥3,600,000)
Fiscal Year 2000 : ¥3,000,000 (Direct Cost : ¥3,000,000)
Fiscal Year 1999 : ¥3,000,000 (Direct Cost : ¥3,000,000)
Fiscal Year 1998 : ¥3,000,000 (Direct Cost : ¥3,000,000)
|Keywords||solar wind changes / polar disturbances / magnetospheric response / transfer process / 210 MM network / equatorial network / global behavior / international collaboration / 大規模電磁場擾乱 / 極冠域 / 赤道域 / 侵入・輸送過程 / 210度観測網 / 赤道域観測網 / 総合データ解析 / 国際共同観測 / エネルギー侵入・伝播過程|
A purpose of this study is to understand a large-scale electromagnetic penetration and propagation process in the atmospheric transition region (the region from 80 to 5-600 Km in the height where neutral and charged particles are mixed in) from the polar to equatorial regions. By using the solar wind and particle data from the WIND and ISTP satellites, we clarified the relationships between the temporal and spatial scales of disturbances in the solar wind and the large-scale electromagnetic disturbances that can penetrate even into the equatorial region on the ground. Especially, in term of the composite data analysis from the satellites and ground-based observations, we can theoretically understand the electromagnetic coupling process between the polar and equatorial regions, including the solar wind, magnetosphere, ionosphere, atmosphere and conductive earth.
(1) A study on a propagation of the transient response of the magnetosphere
In this study, by investigation of the characteristi
cs of the polarization of magnetic variations on the ground due to the SI-event, we cleared that magnetic variations in the polar region associated with SC/SI events could be interpreted only by a motion of the vortex currents generated in the polar ionosphere. The motion of the ionosphere vortex current includes the information of the deformation of the magnetopause. Therefore, the present results suggest a possibility of the monitoring for the transient response of the whole magnetosphere from ground magnetic variations.
(2) A study on a global propagation of the ULF pulsations
From analyses of magnetic data from the Circum-pan-Pacific Magnetometer Network (CPMN) stations, it can be concluded that Pi 2 magnetic pulsations observed on the ground consist of at least five components : (1) a bouncing mode of impulsive field-aligned current at the auroral latitude, (2) a substorm current wedge oscillation (3) a surface wave at the plasmapause, (4) a cavity-like oscillation in the inner magnetosphere, and (5) a transmission of the Pi 2 electric field from the nightside auroral latitude to the dayside equatorial region. The ground Pi 2 pulsations are an ensemble of these five modes, which show their own propagations (or timings) and spatial illuminations.
(3) A study on the disturbance of the electric field in the ionosphere
In order to investigate the electric disturbances in the ionosphere, we installed the FM/CW radar at SASAGURI (Fukuoka City), and made steady observation of the variations of the ionosphere. As a result, we could successfully detect the temporal and spatial variations of the ionosphere due to the imposed electric field on the polar ionosphere. These observations reveal that the electric field imposed on the polar ionosphere spread event to the equatorial region almost simultaneously.