2020 Fiscal Year Final Research Report
Ground-based optical observations for short wavelength infrared aurora emissions: A challenge to visualizing dayside magnetosphere
| Project/Area Number |
17H04857
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| Research Category |
Grant-in-Aid for Young Scientists (A)
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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 | National Institute of Polar Research |
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Principal Investigator |
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| Project Period (FY) |
2017-04-01 – 2020-03-31
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| Keywords | オーロラ / 大気光 / 地上観測 / 短波長赤外分光 / 磁気圏-電離圏結合 / 中間圏界面 / 南極・北極 / OH回転温度 |
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| Outline of Final Research Achievements |
The purpose of this study is to challenge the aurora detection in twilight/sunlit conditions from a ground-based spectroscopic observation in the relatively weak short wavelength infrared (1.0-1.6 μm) of solar radiations. As a preliminary investigation, a consumer product-based spectrometer was installed at Syowa Station, Antarctica in February 2018, and observations were continued until the beginning of November of the same year. Aurora intensification of N2 molecule and N2+ molecular ions associated with large aurora activity was successfully identified in several cases.
Based on these spectroscopic data, we proceeded with the development of a cutting-edge imaging spectrometer for daytime aurora observation. Designing the spectrometer mainly for 1.1 μm N2 + aurora emissions with two imaging modes, high spectral resolution and wide spectral range, manufacturing the spectrometer housing and assembling the entire device, checking the operation of moving parts such as motors were done.
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| Free Research Field |
超高層大気物理学
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| Academic Significance and Societal Importance of the Research Achievements |
1.0-1.5μm帯におけるオーロラ分光データを、地上からInGaAs検出器によって高時間分解能(30s)で取得したのは世界初であり、今後の短波長赤外観測の発展に重要なデータを示した。また、波長1.5μm付近のN2+分子イオンのオーロラ発光が、同じ波長域で常時発光するOH分子に比べ、発光強度が10倍以上大きいことを示した。1.5μmでのOH分子発光の観測は、オーロラ発光の影響が少ないと考えられてきたが、その定説を覆しオーロラ出現時にはOH分子発光による正確な温度推定が難しいことを観測的に初めて示した。昭和基地における分光データの一部は、DOIを取得し、プロジェクトHP上で数値データを公開した。
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