Plasma and Field Observations in the Magnetospheric Source Region of a Stable Auroral Red (SAR) Arc by the Arase Satellite on 28 March 2017
Plasma and Field Observations in the Magnetospheric Source Region of a Stable Auroral Red (SAR) Arc by the Arase Satellite on 28 March 2017
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DOI：
10.1029/2020ja028068
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发表时间：
2020-09
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通讯作者：
Y. Inaba;K. Shiokawa;S. Oyama;Y. Otsuka;A. Oksanen;A. Shinbori;A. Gololobov;Y. Miyoshi;Y. Kazama;Shiang‐Yu Wang;S. Tam;T. Chang;Bo‐Jhou Wang;S. Yokota;S. Kasahara;K. Keika;T. Hori;A. Matsuoka;Y. Kasahara;A. Kumamoto;Y. Kasaba;F. Tsuchiya;M. Shoji;I. Shinohara;C. Stolle
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作者：
Y. Inaba;K. Shiokawa;S. Oyama;Y. Otsuka;A. Oksanen;A. Shinbori;A. Gololobov;Y. Miyoshi;Y. Kazama;Shiang‐Yu Wang;S. Tam;T. Chang;Bo‐Jhou Wang;S. Yokota;S. Kasahara;K. Keika;T. Hori;A. Matsuoka;Y. Kasahara;A. Kumamoto;Y. Kasaba;F. Tsuchiya;M. Shoji;I. Shinohara;C. Stolle
稳定的极光红 (SAR) 弧是在亚极光纬度以 630 nm 发射为主的极光。 SAR 弧被认为是由于等离子体层和环流离子之间的空间重叠而发生的。在重叠区域，等离子体层电子被环流离子或等离子体波加热，然后它们的能量向下转移到电离层，在那里引起氧红发射。然而，迄今为止还没有进行定量研究与合成孔径雷达电弧相关的磁层中的等离子体和电磁场的研究。在本文中，我们报告了对 2017 年 3 月 28 日在 2204 UT 观测到的 SAR 弧共轭测量的首次定量评估，并使用芬兰 Nyrölä（磁纬度：59.4°N）的全天成像仪和 Arase 卫星研究其源区域。 Arase观测表明，SAR弧出现在等离子体层羽流与环流离子的重叠区域，在SAR弧上方没有观测到电磁离子回旋波和动能阿尔文波。 SAR 弧位于从 GNSS 接收器网络获得的总电子含量图确定的电离层波谷最小值处。在电离层中飞行的 Swarm 卫星也在约 2320 UT 时经过了 SAR 弧，并观察到在穿越 SAR 弧期间电子密度降低和电子温度升高。这些观察结果表明，通过与环流离子的库仑碰撞加热等离子体层电子是SAR弧产生的最可能的机制。
A stable auroral red (SAR) arc is an aurora with a dominant 630 nm emission at subauroral latitudes. SAR arcs have been considered to occur due to the spatial overlap between the plasmasphere and the ring‐current ions. In the overlap region, plasmaspheric electrons are heated by ring‐current ions or plasma waves, and their energy is then transferred down to the ionosphere where it causes oxygen red emission. However, there have been no study conducted so far that quantitatively examined plasma and electromagnetic fields in the magnetosphere associated with SAR arc. In this paper, we report the first quantitative evaluation of conjugate measurements of a SAR arc observed at 2204 UT on 28 March 2017 and investigate its source region using an all‐sky imager at Nyrölä (magnetic latitude: 59.4°N), Finland, and the Arase satellite. The Arase observation shows that the SAR arc appeared in the overlap region between a plasmaspheric plume and the ring‐current ions and that electromagnetic ion cyclotron waves and kinetic Alfven waves were not observed above the SAR arc. The SAR arc was located at the ionospheric trough minimum identified from a total electron content map obtained by the GNSS receiver network. The Swarm satellite flying in the ionosphere also passed the SAR arc at ~2320 UT and observed a decrease in electron density and an increase in electron temperature during the SAR‐arc crossing. These observations suggest that the heating of plasmaspheric electrons via Coulomb collision with ring‐current ions is the most plausible mechanism for the SAR‐arc generation.