1988 Fiscal Year Final Research Report Summary
AURORAL DYNAMICS AND PARTICLE PROCESSES IN THE MAGNETOSPHERE.
| Project/Area Number |
62460049
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Space and upper atmospheric physics
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| Research Institution | University of Tokyo |
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Principal Investigator |
OGUTI Takasi Faculty of Science, University of Tokyo, 理学部, 教授 (40011457)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAMOTO Tatsundo Faculty of Science, University of Tokyo, 理学部, 助手 (90182633)
HAYASHI Kanji Faculty of Science, University of Tokyo, 理学部, 助教授 (60011730)
TAMAO Tsutomu Faculty of Science, University of Tokyo, 理学部, 教授 (50013636)
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| Project Period (FY) |
1987 – 1988
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| Keywords | Aurora / Pulsating aurora / Ionospheric current / Electron precipitation / Geomagnetic pulsation / Magnetospheric electric field / IPDP脈動 |
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| Research Abstract |
Two dimensional structures and dynamics of auroral images were examined to study magentosphere-ionosphere link based on all-sky video data acquired at 9 sites during Global Aurora Dynamics Campaign (Dec. 1985 - Jan. 1986).
1. Large scale evolutions of auroras in a global extent of 9 key stations were studied based on all-sky TV record, and the northward protrusions are found to develop and decay one after another along the poleward front of an expansion aurora. Distribution of the ground magnetic field deflections concurrent with the auroral deformations indicates that the regions of the westward electrojet associated with the auroral protrusions are spatially limited. The localized signature of the jet-current have been related to the fact found in space that sudden changes in magnetic field occur at synchronous orbit when an auroral protrusion develops in the vicinity of the conjugate point determined by field-line tracing in a model magnetic field.
2. Close relationships have been fou
… More
nd bewteen Pc5 magnetic pulsations and concurrent periodic appearance and movement of auroral structures during magnetic substorm. Characteristics of the pulsations were examined as the effects of electric field and electric conductivity changes in the ionosphere, which were estimated from oscillations in auroral drift motion and in auroral luminosity, respectively. Neither of simple models which include only electric field modulation or only conductivity modulation could not explain the phase relation bewteen the Pc5 pulsations and auroral pulsations during substorm.
3. Near the dayside cusp, small auroral expansions continually occur with a sequence of 10 minutes or so. Bursts of magnetic pulsations in the frequency range of 0.3-0.8 Hz and impulsive magnetic variations of several minute duration were often associated with poleward motions of short-lived auroral expansions. The transient poleward motions occurred coincidentally with the equatorward shift of auroral oval in the afternoon region.
4. Signatures indicating localized source region of Pc 1 micropulsations were confirmed in high density UIF network data on the ground, both in magnetic field and in proton precipitation data of low altitude satellite, and in a theoretical model. Less
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