1990 Fiscal Year Final Research Report Summary
Mechanism of Substorm Expansion Onset
| Project/Area Number |
01540352
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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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 | Kyoto Sangyo University |
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Principal Investigator |
KAMIDE Yohsuke Kyoto Sangyo University, Faculty of Science, Professor, 理学部, 教授 (60113099)
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| Project Period (FY) |
1989 – 1990
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| Keywords | Earth's Magnetosphere / Substorm / Aurora / Ionosphere / Auroral electrojet / Satellite image / Polar phenomena / Magnetic disturbances |
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| Research Abstract |
This research has attempted to explore the physical mechanism of magnetospheric substorms, which are the most fundamental global and localized disturbance occurring in the magnetosphere-ionosphere coupling system. For this purpose, high-quality ground magnetometer data are combined with satellite observations of the UV auroral distributions and a revised version of the magnetogram-inversion algorithm which can now take "instantaneous", not "statistical", distributions of the height-integrated ionospheric conductivity. The following are the main findings :
1. The westward electrojet, which is gradually intensified before the onset of the substorm expansion, is most intense near 0600 MLT (magnetic local time), not in the midnight sector. This enhancement reflects probably the effect of an enhancement in the electric field which is the effect of southward IMF (interplanetary magnetic field).
2. When the so-called rheta aurora exists before substorm onset, the subsequent auroral break-up occurs at the location where the rheta aurora and the normal oval aurora meet together.
3. The size of the polar cap is one of the crucial parameters which signify the available energy being stored in the magnetotail. Since it is impossible to accurately determine the polar cap boundary which is the boundary between open and closed magnetic field lines, the boundary has been estimated by using the distribution of electric fields and currents obtained from the inversion technique. It is found that the difference in the different estimate is as much as 5^ﾟ in latitude.
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[Publications] Richmond, A. D., Y. Kamide, S. -I. Akasofu, D. Alcayde, M. Blanc, O. de la Beaujardiere, D. S. Evans, J. C. Foster, E. Friis-Christensen, J. M. Holt, R. J. Pellinen, C. Senior, and A. N. Zaitzev: "Global measures of ionospheric electrodynamic activity inferred from combined incoherent-scatter radar and ground magnetometer observations" J. Geophys. Res.95. 1061-1071 (1990)
Description
「研究成果報告書概要(欧文)」より
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[Publications] Fejer, B. G., M. C. Kelley, C. Senior, O. de la Beaujardiere, J. M. Holt, C. A. Tepley, R. Burnside, M. A. Abdu, J. H. A. Sobral, R. F. Woodman, Y. Kamide, and R. Lepping: "Low- and mid-latitude ionospheric electric fields during the January 1984 GISMOS campaign" J. Geophys. Res.95. 2367-2377 (1990)
Description
「研究成果報告書概要(欧文)」より
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