| Project/Area Number |
17K05669
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Space and upper atmospheric physics
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| Research Institution | Kyoto University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
齊藤 昭則 京都大学, 理学研究科, 准教授 (10311739)
能勢 正仁 名古屋大学, 宇宙地球環境研究所, 准教授 (90333559)
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| Project Period (FY) |
2017-04-01 – 2021-03-31
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| Project Status |
Completed (Fiscal Year 2020)
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| Budget Amount *help |
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2019: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2018: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2017: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
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| Keywords | 電離圏電子密度 / 磁気リップル / 重力音波 / 音波共鳴 / 電離層ダイナモ / 赤道電子密度異常 / 降雨 / 微気圧変動 / 電離層電子密度変動 / Swarm衛星 / 全球降水マップ / 地磁気変動 / magnetic ripple / acoustic gravity wave / ionosphere / electron density / Swarm satellites / GPS-TEC変動 / 積雲対流 / magnetic ripples / field-aligned currents / acoustic waves / ionospheric dynamo / micro-barometer |
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| Outline of Final Research Achievements |
The relationship between two small scale phenomena of magnetic and electron density variations with spatial scale shorter than 100-300km, both of which are observed in low-latitude ionospheric F-region on the dayside, and their source were investigated by using the ESA/Swarm satellite data (vector magnetic field and electron density) and ground based micro-barometric, GPS-TEC, rainfall data observed at an unmanned observatory in Phimai/Thailand. It was suggested a mutual relationship among the two ionospheric phenomena and rainfall from some case studies. The averaged global distribution of the two ionospheric phenomena and their comparison with global rainfall distribution obtained from JAXA/GSMaP data also suggest the possible relation with rainfall. However, the results were still not conclusive enough and more analysis is necessary.
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| Academic Significance and Societal Importance of the Research Achievements |
低高度極軌道衛星で常時観測される磁気リップルは下層大気から電離圏に伝搬する大気波動が原因であると推測されるが、対応する気象現象や波動のモードについては明確な結論が得られていない。また、当研究により低緯度昼間側の電離圏F層に、軌道に沿うスケールが約100km-300kmの波状構造が頻繁に出現することが明らかになった。これら現象は、振幅および空間スケールが小さいが、下層大気で生成された音波モードの大気波動が駆動している可能性が高く、内部重力波に比較して研究が比較的少なかった音波モードの大気波動が電離圏プラズマに及ぼす影響、より一般的には中性大気波動と部分電離気体との相互作用という観点で意義がある。
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