Oyama Shin-Ichiro, Tsuda Takuo T, Hosokawa Keisuke, Ogawa Yasunobu, Miyoshi Yoshizumi, Kurita Satoshi, Kero Antti E, Fujii Ryoichi, Tanaka Yoshimasa, Mizuno Akira, Kawabata Tetsuya, Gustavsson Björn, Leyser Thomas
1ISEE Nagoya University, F3-3 Furo Chikusa, Nagoya, Aichi 464-8601 Japan.
2Ionospheric Physics Research Unit, University of Oulu, Pentti Kaiteran katu 1, Linnanmaa, 90014 Oulu, Finland.
Earth Planets Space. 2018;70(1):166. doi: 10.1186/s40623-018-0936-z. Epub 2018 Oct 16.
One of the representative auroral emission lines that radiates from F-region heights and is measurable on the ground is the 777.4 nm line from excited atomic oxygen. This line has been adopted, along with another E-region emission line, for example 427.8 nm, to estimate the mean energy and total energy flux of precipitating auroral electrons. The influence of emissions from part of the molecular nitrogen band, which mainly radiate from E-region heights, should be carefully evaluated because it might overlap the 777.4 nm atomic oxygen line in the spectrum. We performed statistical analysis of auroral spectrograph measurements that were obtained during the winter of 2016-2017 in Tromsø, Norway, to derive the ratio of the intensity of the 777.4 nm atomic oxygen line to that of the net measurement through a typically used optical filter with a full width at half maximum of a few nm. The ratio had a negative trend against geomagnetic activity, with a primary distribution of 0.5-0.7 and a minimum value of 0.3 for the most active auroral condition in this study. This result suggests that the 30-50% emission intensities measured through the optical filter may be from the molecular nitrogen band.
从F层高度辐射且能在地面测量到的代表性极光发射线之一是来自激发态原子氧的777.4纳米谱线。这条谱线与另一条E层发射线（例如427.8纳米）一起，被用于估算沉降极光电子的平均能量和总能量通量。主要从E层高度辐射的部分分子氮带发射的影响应仔细评估，因为它可能在光谱中与777.4纳米的原子氧谱线重叠。我们对2016 - 2017年冬季在挪威特罗姆瑟获得的极光光谱仪测量数据进行了统计分析，以得出777.4纳米原子氧谱线强度与通过半高宽为几纳米的典型光学滤波器进行的净测量强度之比。该比值随地磁活动呈负趋势，在本研究中，对于最活跃的极光条件，其主要分布为0.5 - 0.7，最小值为0.3。这一结果表明，通过光学滤波器测量的30% - 50%的发射强度可能来自分子氮带。
