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

2019 Fiscal Year Annual Research Report

• Project/Area Number: 17H04857
• Research Institution: National Institute of Polar Research
• Principal Investigator: 西山 尚典 国立極地研究所, 研究教育系, 助教 (00704876)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: オーロラ / 地上観測 / 近赤外分光観測 / 大気光 / 磁気圏-電離圏結合 / 超高層物理学 / 中間圏界面

Outline of Annual Research Achievements

2018年度に昭和基地にて観測した分光データ（1.0-1.6μm）の詳細解析を実施した．また，日本に持ち帰った分光器については，再度国内観測を実施し，性能確認ののち，スウェーデンのSwedish Institute of Space Physicsとの共同研究としてキルナに輸送し，自動観測を2019年8月末に再開した．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．キルナにおける観測データも公開に向けて共同研究者と協議を継続している．

昭和基地の観測から，活発なオーロラ活動に伴うN2分子（1.0および1.2μm）とN2+分子イオン（1.1および1.5μm）のオーロラ増光が複数例検出された．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，可視光オーロラ測定による発光強度や電波観測との出現特性の比較を行い，論文化作業を進めた．また，昭和基地・キルナでの観測結果より，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，高度80-90kmの大気温度導出のために近年注目され，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正確な温度推定が難しいことを観測的に初めて示した．この結果は，Earth Planets Space誌にて受理・出版された．

開発中のイメージング分光器については，前年度までの検討・設計に基づき，分光器筐体の製作と装置全体の組み立て，動作検証を行った．加えて，アルゴンランプを用いた波長校正を実施し，ほぼ設計通りの波長範囲（1.1-1.2μm）をスキャンできることを確認した。

Research Progress Status

令和元年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

令和元年度が最終年度であるため、記入しない。

Research Products

• [Int'l Joint Research] Swedish Institute of Space Physics(スウェーデン)
  • Country Name: SWEDEN
  • Counterpart Institution: Swedish Institute of Space Physics
• [Journal Article] Temporal evolutions of N2+ Meinel (1,2) band near 1.5 um associated with aurora breakup and their effects on mesopause temperature estimations from OH Meinel (3,1) band (2021)
  • Author(s): Nishiyama Takanori, Taguchi Makoto, Suzuki Hidehiko, Dalin Peter, Ogawa Yasunobu, Brandstrom Urban, Sakanoi Takeshi
  • Journal Title: Earth, Planets and Space Volume: 73 Pages: 1-12
  • DOI: 10.1186/s40623-021-01360-0
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] OI 630.0‐nm and N2 1PG Emissions in Pulsating Aurora Events Observed by an Optical Spectrograph at Tromso, Norway (2020)
  • Author(s): Tsuda T. T., Li C., Hamada S., Hosokawa K., Oyama S.‐i., Nozawa S., Kawabata T., Mizuno A., Kurihara J., Nishiyama T., Kosch M. J.
  • Journal Title: Journal of Geophysical Research: Space Physics Volume: 125 Pages: 1-11
  • DOI: 10.1029/2020ja028250
  • Peer Reviewed / Int'l Joint Research
• [Presentation] Spectral investigations on short-wavelength infrared airglow and aurora (0.9-1.6 μm) at Syowa station (69.0°S, 39.6°E) using a Czerny-Turner type 1-D imaging spectrograph: A comparison study to a panchromatic InGaAs camera and a resonance scattering lidar (2021)
  • Author(s): T. Nishiyama, T. Nakamura, M. Taguchi, M. K. Ejiri, T. T. Tsuda, H. Suzuki, T. Sakanoi, K. Tsuno, T. Ogawa, S. Wada
  • Organizer: 43rd COSPAR (Committee on Space Research) Scientific Assembly
  • Int'l Joint Research
• [Presentation] Ground-based optical observations for short-wavelength infrared aurora and airglow emissions in Northern Europe (2020)
  • Author(s): T. Nishiyama, M. Kagitani, Y. Ogawa, P. Dalin, U. Brandstrom, M. Taguchi, and T. Sakanoi
  • Organizer: ISAR-6 / Sixth International Symposium on Arctic Research
  • Int'l Joint Research
• [Presentation] Spectral investigations on short-wavelength infrared aurora and airglow (0.9-1.6 μm): Ground-based observations in the both polar regions and developments of 2-D imaging spectrograph with high resolutions (2020)
  • Author(s): T. Nishiyama, M. Taguchi, M. Kagitani, Y. Ogawa, H. Suzuki, T. Sakanoi, F. Tsuchiya, P. Dalin, U. Brandstrom
  • Organizer: Japan Geoscience Union - American Geophysical Union Joint Meeting 2020
  • Int'l Joint Research
• [Presentation] Temporal evolutions of N2+ Meinel (1,2) band near 1.5 um associated with aurora breakup and their effects on mesopause temperature estimations from OH Meinel (3,1) band (2020)
  • Author(s): T. Nishiyama, M. Taguchi, H. Suzuki, P. Dalin, Y. Ogawa, U. Brandstrom, and T. Sakanoi
  • Organizer: The Eleventh Symposium on Polar Science
  • Int'l Joint Research
• [Presentation] Spectral investigations of near infrared aurora and airglow at 1.0-1.6 microns: 1-year ground-based imaging spectroscopic observation at Syowa station (69.0°S, 39.6°E) (2019)
  • Author(s): Takanori Nishiyama, Takeshi Sakanoi, Makoto Taguchi, Hidehiko Suzuki
  • Organizer: Japan Geoscience Union Meeting 2019
• [Presentation] Spectral investigations of near infrared aurora and airglow in 1.0-1.6 microns using InGaAs imaging spectrograph:1-year ground-based observation at Syowa station (69.0°S, 39.6°E) (2019)
  • Author(s): Takanori Nishiyama, Takeshi Sakanoi, Makoto Taguchi, M. Kagitani, P. Dalin, Hidehiko Suzuki
  • Organizer: 19th International EISCAT Symposium and 46th Annual European Meeting on Atmospheric Studies by Optical Methods
  • Int'l Joint Research
• [Presentation] Near infrared optical observations in the Northern Europe:Extension of dayside aurora and airglow measurements from the ground (2019)
  • Author(s): Takanori Nishiyama, Masato Kagitani, Yasunobu Ogawa, Takeshi Sakanoi, Makoto Taguchi
  • Organizer: 第146回 地球電磁気・地球惑星圏学会 総会および講演会
• [Presentation] Current status of ground-based optical observations for short-wavelength infrared aurora and airglow emissions in Northern Europe (2019)
  • Author(s): T. Nishiyama, M. Kagitani, Y. Ogawa, P. Dalin, U. Brandstrom, M. Taguchi, and T. Sakanoi
  • Organizer: The Tenth Symposium on Polar Science
  • Int'l Joint Research
• [Remarks] Near InfraRed Aurora and airglow Spectrograph HP
  • URL: http://polaris.nipr.ac.jp/~niras/index.html#!index.md
• [Remarks] NIRAS data landing page
  • URL: https://scidbase.nipr.ac.jp/modules/metadata/index.php?content_id=390&ml_lang=en