2021年1月
Temporal evolutions of N2+ Meinel (1,2) band near 1.5 μm associated with aurora breakup and their effects on mesopause temperature estimations from OH Meinel (3,1) band
Earth, Planets and Space
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- 巻
- 73
- 号
- 30
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1186/s40623-021-01360-0
- 出版者・発行元
- SpringerOpen
We have carried out ground-based NIRAS (Near-InfraRed Aurora and airglow Spectrograph) observations at Syowa station, Antarctic (69.0°S, 39.6°E) and Kiruna (67.8°N, 20.4°E), Sweden for continuous measurements of hydroxyl (OH) rotational temperatures and a precise evaluation of auroral contaminations to OH Meinel (3,1) band. A total of 368-nights observations succeeded for two winter seasons, and three cases in which N2+ Meinel (1,2) band around 1.5 μm was significant were identified. Focusing on two specific cases, detailed spectral characteristics with high temporal resolutions of 30 seconds are presented. Intensities of N2+ band were estimated to be 228 kR and 217 kR just at the moment of the aurora breakup and arc intensification during pseudo breakup, respectively. At a wavelength of P1(2) line ( ∼ 1523 nm), N2+ emissions were almost equal to or greater than the OH line intensity. On the other hand, at a wavelength of P1(4) line ( ∼ 1542 nm), the OH line was not seriously contaminated and still dominant to N2+ emissions. Furthermore, we evaluated N2+ (1,2) band effects on OH rotational temperature estimations quantitatively for the first time. Auroral contaminations from N2+ (1,2) band basically lead negative bias in OH rotational temperature estimated by line-pair-ratio method with P1(2) and P1(4) lines in OH (3,1) band. They possibly cause underestimations of OH rotational temperatures up to 40 K. In addition, N2+ (1,2) band contaminations were temporally limited to a moment around the aurora breakup. This is consistent with proceeding studies reporting that enhancements of N2+ (1,2) band were observed associated with International Brightness Coefficient 2-3 auroras. It is also suggested that the contaminations would be neglected in the polar cap and the sub-auroral zone, where strong aurora intensification are less observed. Further spectroscopic investigations at these wavelengths are needed especially for more precise evaluations of N2+ (1,2) band contaminations. For example, simultaneous 2-D imaging observation and spectroscopic measurement with high spectral resolutions for airglow in OH (3,1) band will make great advances in more robust temperature estimations in the auroral zone.
- リンク情報
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- DOI
- https://doi.org/10.1186/s40623-021-01360-0 本文へのリンクあり
- 共同研究・競争的資金等の研究課題
- 多波長近赤外分光・イメージング観測で解明する昼側オーロラ特性と地球大気の組成変動
- 共同研究・競争的資金等の研究課題
- 近赤外分光イメージングによる日照下オーロラ観測
- 共同研究・競争的資金等の研究課題
- 近赤外波長領域で開拓する地上オーロラ光学観測:昼側磁気圏可視化への挑戦
- Scopus
- https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85100067041&origin=inward 本文へのリンクあり
- Scopus Citedby
- https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85100067041&origin=inward
- ID情報
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- DOI : 10.1186/s40623-021-01360-0
- ISSN : 1343-8832
- eISSN : 1880-5981
- SCOPUS ID : 85100067041