2001 Fiscal Year Final Research Report Summary
Quantitative studies of the Earth's ionospheric-origin ions on the outflow/supply to the magnetosphere and the acceleration/heating and transpotation processes
| Project/Area Number |
10440138
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Space and upper atmospheric physics
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| Research Institution | RIKKYO UNIVERSITY |
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Principal Investigator |
HIRAHARA Masafumi RIKKYO UNIV COLLEGE OF SCIENCE, ASSISTANT PROFESSOR, 理学部, 助教授 (50242102)
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| Co-Investigator(Kenkyū-buntansha) |
ABE Takumi INSTITUTE OF SPACE AND ASTRONAUTICAL SCIENCE ASSISTANT PROFESSOR, 惑星大気系, 助教授 (40255229)
MIYAKE Wataru COMMUNICATIONS RESEARCH LAB. SENIOR RESEARCHER, 通信総合研究所, 主任研究官
WATANABE Shigeto HOKKAIDO UNIV. FACULTY OF SCIENCE PROFESSOR, 大学院・理学研究科, 教授 (90271577)
MUKAI Toshifumi INSTITUTE OF SPACE AND ASTRONAUTICAL SCIENCE PROFESSOR, 太陽系プラズマ系, 教授 (60013695)
KASAHARA Yoshiya KYOTO UNIV FACULTY OF ENGINEERING ASSISTANT, 大学院・工学研究科, 助手 (50243051)
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| Project Period (FY) |
1998 – 2000
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| Keywords | Ionospheric-origin ion / Ion acceleration and heating / Polar wind / Ion conics / Plasma wave / Ion escape |
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| Research Abstract |
First of all, we investigated the properties of plasma waves which are expected to cause the ionospheric ion acceleration/heating on the basis of the Akebono satellite observations. The relationships of these waves to the outflowing ion conics were statistically surveyed especially from aspects of their occurrence frequencies of events sorted into altitudes, pitch angles, magnetic latitude, and local time. Our detailed wave analyzes presented two types of wave forms, namely, low-frequency random noise-type wave and sporadic spike-type wave, two of which superimpose each other. The importance of photoelectron effects on polar wind events is also become clear according to the Akebono data analyzes. On one hand, the recent results of multi-satellite observation data verified the dependence of the conics events on the interplanetary magnetic field. We also analyzed the Geotail data for estimate of the outflow fluxes in the magnetosphere of the ionospheric origin ions after their escape from the polar ionosphere. It should be noted that we take all routes of the ionospheric ions after the ejection from the terrestrial atmosphere into account in order to calculate correct amount of the terrestrial-origin ions in the magnetosphere. The recent observation data from EISCAT were used for exploring the ionospheric ion heating phenomena at low altitutes where at is expected that the ion outflows are triggered. It is likely that the anisotropic pitch angle distribution plays an crucial role for ion heating/acceleration as a cause of the ion outflow events observed at high altitudes.
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