| Project/Area Number |
60540266
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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, 理学部, 教授 (60113099)
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| Project Period (FY) |
1985 – 1986
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| Project Status |
Completed (Fiscal Year 1986)
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| Budget Amount *help |
¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1986: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1985: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Earth's magnetosphere / Ionosphere / Aurora / Auroral electrojet / Solar wind / 沿磁力線電流 |
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| Research Abstract |
Starting with ground-based magnetometer records, an attempt is made to estimate electric fields and currents in the ionosphere as well as field-aligned currents, aiming to discuss electrodynamic processes in the magnetosphere. Our goal is to combine the KRM magnetogram-inversion scheme and the so-called Rice University convection model. This project consists primarily of two studies: (1) Images of auroral emissions observed with Dynamics Explorer (DE)1 are used to calculate ionospheric conductivities over the polar region. The combination of ground-based magnetometer data and the inferred conductivities enables us to estimate on a global scale the distributions of ionospheric electric fields and currents and field-aligned currents, as well as the Joule heating production rate. It is found that the westward electrojet is collocated with the region of high auroral luminosity, while the region of relatively low luminosity in the evening sector is collocated with the eastward electrojet, a
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nd the upward field-aligned currents exist in the brightest auroral region on the poleward side of the evening auroral oval and on the equatorward side of the morning oval. (2) Using auroral and ion drift data from the DE 1 and 2 satellites, which fortuitously passed high latitudes of the northern hemisphere within a few minutes of one another, an attempt is made to estimate the global distribution of ionospheric electric fields and currents as well as of field-aligned currents. For this purpose, ground-based magnetic observations are combined with the so-called magnetogram-in-version technique, and the Rice University model for the ionospheric conductivity is improved to match the auroral distribution derived from auroral images observed by DE 1. The optimum conductivity is then chosen numerically in such a way that the resultant electric fields become consistent with DE 1 ion drifts. The following are the main results shown in this study: (1) Statistical conductivity models are not most suitable to be used in the magnetogram-inversion technique for individual substorm cases. (2) Significant electric fields exist at times to explain an intense auroral electrojet current in the region where auroral activity and the corresponding conductivity is low. Less
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