Fragmented Aurora-like Emissions (FAEs) as a new type of aurora-like phenomenon
Fragmented Aurora-like Emissions (FAEs) as a new type of aurora-like phenomenon
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DOI：
10.5194/angeo-2020-45
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发表时间：
2020-08
影响因子：
1.9
通讯作者：
J. Dreyer;N. Partamies;D. Whiter;P. Ellingsen;L. Baddeley;Stephan Buchert
中科院分区：
文献类型：
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作者：
J. Dreyer;N. Partamies;D. Whiter;P. Ellingsen;L. Baddeley;Stephan Buchert
抽象。这项研究分析了一种新型的小尺度极光特征的观测结果，这种特征被进一步称为碎片状极光发射（FAE）。2015年和2017年，一台全天空摄像机在斯瓦尔巴特群岛北极城镇朗伊尔本附近的Kandel-Henriksen天文台三次拍摄到了这些FAE。共有305名FAE候选人被确定为不同程度的确定性。它们似乎出现在两个类别中-随机发生的单个FAE和FAE之间沿极光弧规则间隔的波浪状结构。FAE的水平尺寸通常低于20公里，缺乏场向发射范围，寿命短，不到一分钟。在原子氧的557.7 nm线和673.0 nm（N2，第一正带系统）处观察到发射，但在N2+的427.8 nm发射或原子氧的777.4 nm线处没有观察到发射。这表明了产生机制的能量的极限。它们缺乏场对准的程度表明了与极光不同的生成机制，极光是由粒子沉淀引起的。相反，这些FAE可能是热电离层电子激发的结果。FAE观测似乎伴随着110-120公里之间的电子温度升高和F区高度的离子温度升高。一个可能的解释是Farley-Buneman不稳定性强的本地电流。我们提供了一个概述的意见，并讨论他们以及潜在的生成机制，在本研究中。
Abstract. This study analyses the observations of a new type of small-scale aurora-like feature, which is further referred to as Fragmented Aurora-like Emission(s) (FAEs). An all-sky camera captured these FAEs on three separate occasions in 2015 and 2017 at the Kjell-Henriksen Observatory near the arctic town of Longyearyben, Svalbard. A total of 305 FAE candidates were identified with varying degrees of certainty. They seem to appear in two categories – randomly occurring individual FAEs and wave-like structures with regular spacing between FAEs alongside auroral arcs. FAEs show horizontal sizes typically below 20 km, a lack of field-aligned emission extent and short lifetimes of less than a minute. Emissions were observed at the 557.7 nm line of atomic oxygen and at 673.0 nm (N2, first positive band system), but not at the 427.8 nm emission of N2+ or the 777.4 nm line of atomic oxygen. This suggests a limit to the energy of the generating mechanism. Their lack of field-aligned extent indicates a different generation mechanism than for aurora, which is caused by particle precipitation. Instead, these FAEs could be the result of excitation by thermal ionospheric electrons. FAE observations are seemingly accompanied by elevated electron temperatures between 110–120 km and increased ion temperatures at F-region altitudes. One possible explanation for this are Farley-Buneman instabilities of strong local currents. We provide an overview of the observations and discuss them as well as potential generation mechanisms in the present study.