オーロラ帯電離圏において短周期(10-90分)の波状構造を持つプラズマおよび中性大気運動の力学的結合
名古屋大学 Nagoya University 博士(理学) Ions in the ionosphere are drifted through the process of the cross product of the electric and magnetic fields, momentum transfer from neutrals to ions through collisions, and diffusion caused by the pressure gradient mainly along geomagnetic field lines. At high lati...
| Main Authors: | , , , |
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| Language: | English |
| Published: |
2001
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| Subjects: | |
| Online Access: | http://hdl.handle.net/2237/11221 https://nagoya.repo.nii.ac.jp/record/9441/files/ko4940.pdf |
| Summary: | 名古屋大学 Nagoya University 博士(理学) Ions in the ionosphere are drifted through the process of the cross product of the electric and magnetic fields, momentum transfer from neutrals to ions through collisions, and diffusion caused by the pressure gradient mainly along geomagnetic field lines. At high latitudes, the electric field and precipitating particles originated in the magnetosphere significantly affect motions of ions. Motions of ions during geomagnetically active intervals can disturb those of neutrals in the auroral thermosphere through collisions between ions and neutrals. For example, wavelike structures in the motions of neutrals at oscillation periods from a few tens minutes to a few hours are generated by enhancements of plasma flow, or the electric field [Hunsucker, 1982 and references therein]. For more than four decades, wavelike structures such as gravity waves in the thermosphere have been the subject of many theoretical and experimental studies on thermospheric and ionospheric motions during auroral activity. There are, however, many unresolved aspects of the wavelike structures in the auroral ionosphere and thermosphere. Two of them are, (1) dynamical coupling of plasma motions and neutral winds in the presence of wavelike structures in short time-scale (10-90 min) in the auroral ionosphere, and (2) relationships between wavelike structures and ionospheric disturbances in association with auroral acts. We conduct three analyses on these topics using data observed mainly with the European Incoherent Scatter (EISCAT) radar, a scanning Fabry-Perot interferometer (FPI), and an all-sky auroral camera:・Dynamical coupling between oscillations of ions and neutrals in short timescale from simultaneous observations between the EISCAT radar and the scanning FPI (λ= 630.0nm),・Statistical analysis of the ion velocity, along the geomagnetic field line, observed with the KST (Kiruna-sodankylä -Troms ø) EISCAT radar and ESR (EISCAT Svalbard Radar), ・Relationship between wavelike structures and ionospheric ... |
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