日本地球惑星科学連合2019年大会

講演情報

[J] ポスター発表

セッション記号 P (宇宙惑星科学) » P-EM 太陽地球系科学・宇宙電磁気学・宇宙環境

[P-EM16] 大気圏・電離圏

2019年5月30日(木) 15:30 〜 17:00 ポスター会場 (幕張メッセ国際展示場 8ホール)

コンビーナ:大塚 雄一(名古屋大学宇宙地球環境研究所)、津川 卓也(情報通信研究機構)、川村 誠治(国立研究開発法人 情報通信研究機構)

[PEM16-P03] 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)

*西山 尚典1坂野井 健2田口 真3鈴木 秀彦4 (1.国立極地研究所、2.東北大学大学院 理学研究科附属 惑星プラズマ・大気研究センター、3.立教大学理学部、4.明治大学理工学部物理学科)

キーワード:近赤外波長領域、分光観測、オーロラ、大気光、中間圏界面、南極

The motivation of this study is further understanding of dayside magnetosphere and terrestrial atmosphere coupling system by using continuous observation. Dayside aurora, polar patch, and airglow should be key phenomena for the understanding. In particular, those phenomena in near infrared (NIR) wavelength are crucially important because lower background sky luminosity by Rayleigh scattering may allow us to conduct ground-based optical observation even in dayside. Continuous dayside optical monitoring with high temporal and spatial resolutions in aurora region and cusp give us a clue to understanding of substorm pre-onset sequences at cusp region, magnetopause dynamics related to solar wind shocks, and wave-particle interactions due to electromagnetic ion cyclotron waves and whistler mode chorus. However, NIR aurora has a total lack of its spectral information with enough resolution to make a feasibility study in comparison to that in visible wavelength.

We designed a narrow field spectrometer with medium-high spectral resolution that mainly consists of Czerny-Turner type imaging spectrometer (HORIBA, iHR320) with one entry port and two exit ports. This spectrometer has two mirrors and three diffractive gratings in a rotating turret. A toroidal mirror for collimating corrects for astigmatism so that the tangential (resolution optimized) and sagittal (imaging optimized) focal planes cross at the center of the focal plane. Another larger focus mirror allows the entire flat field to be used without vignetting. Collecting optics, equipped outside the spectrometer, are a gold coated off-axis parabolic mirror and a NIR longpass filter for removal of secondary diffracted light in visible wavelength. Using 1-d InGaAs array (1024 pixels) and 600 gr/mm grating, spectral range and spectral range per pixel are 119 nm and 0.11 nm/pixel, respectively.

We started ground-based spectroscopic observation in NIR wavelength ranging from 1.0 to 1.6 microns, which covers strong OH airglow emissions and auroral emissions in N21st Positive (1.2 microns) and N2+Meinel (1.1 and 1.5 microns) [Jones 1974; Zhou et al., 2007], at Syowa Station (69.0°S, 39.6°E) in Antarctica from March 2018. OH airglow spectrum in NIR can be well resolved even in water vapor absorption region. OH rotational temperature is successfully estimated using OH 3-1 band P1(2) and P1(4) emissions. However, auroral emissions were not clearly identified at 1.52 micron (N2+ Meinel) so far. Further investigations are needed including 1.10 micron (N2+ Meinel) and 1.24 micron (N2 1P). In this presentation, we are going to report results in more detail based on one year observation.