Unsolved problems in Strong Thermal Emission Velocity Enhancement (STEVE) and the picket fence
Unsolved problems in Strong Thermal Emission Velocity Enhancement (STEVE) and the picket fence
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DOI：
10.3389/fspas.2023.1087974
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发表时间：
2023-01
期刊：
影响因子：
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通讯作者：
Y. Nishimura;Alan Dyer;Lauri Kangas;E. Donovan;V. Angelopoulos
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文献类型：
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作者：
Y. Nishimura;Alan Dyer;Lauri Kangas;E. Donovan;V. Angelopoulos
本文综述了强热辐射速度增强（STEVE）和栅栏的关键性质和主要未解决的问题。我们首先介绍了STEVE的基本特征和历史上观测到的类STEVE辐射，特别是1891年9月11日的观测。然后，我们讨论了关于史蒂夫的主要公开问题：1）为什么史蒂夫优先出现在春分点？2)太阳风和风暴/亚暴条件如何控制史蒂夫？3)尽管史蒂夫似乎不需要极端的驾驶条件，但为什么史蒂夫却很少见？4)STEVE的多尺度结构是什么？5)是什么机制决定了尖桩篱笆的特性？6)STEVE的化学和发射机制是什么？7)STEVE对电离层-热层系统有什么影响？此外，8）史蒂夫，稳定的极光红（SAR）弧，和亚极光质子极光之间的关系是什么？这些问题主要涉及STEVE是如何作为极光下磁层-电离层-热层耦合系统的一种独特的响应模式而产生的。史蒂夫，合成孔径雷达弧和质子极光，三种主要类型的亚极光发射，需要高能粒子注入到午夜前的内磁层和冷等离子体的相互作用。然而，人们不明白为什么它们发生在不同的时间，为什么它们可以共存并从一个过渡到另一个。强烈的电子注入到午夜前的部门被认为是重要的驱动激烈的亚极光离子漂移（SAID）。磁层如何创建不同的注入功能，驱动极光下的流动，并扰乱热层创建光发射的系统级的理解是需要解决的关键问题史蒂夫。应该进行考虑极端速度和加热的电离层-热层建模，以回答发生了什么化学和动力学过程以及STEVE光度可以解释多少。公民科学家的照片和科学仪器揭示了史蒂夫的精细尺度结构的演变及其与尖桩篱笆的联系。照片还显示了史蒂夫和局部尖桩围栏的波动。需要高分辨率观测来解析STEVE和尖桩栅栏的精细尺度结构，这种观测对于了解电离层和热层的基本过程非常重要。
This paper reviews key properties and major unsolved problems about Strong Thermal Emission Velocity Enhancement (STEVE) and the picket fence. We first introduce the basic characteristics of STEVE and historical observations of STEVE-like emissions, particularly the case on 11 September 1891. Then, we discuss major open questions about STEVE: 1) Why does STEVE preferentially occur in equinoxes? 2) How do the solar wind and storm/substorm conditions control STEVE? 3) Why is STEVE rare, despite that STEVE does not seem to require extreme driving conditions? 4) What are the multi-scale structures of STEVE? 5) What mechanisms determine the properties of the picket fence? 6) What are the chemistry and emission mechanisms of STEVE? 7) What are the impacts of STEVE on the ionosphere−thermosphere system? Also, 8) what is the relation between STEVE, stable auroral red (SAR) arcs, and the subauroral proton aurora? These issues largely concern how STEVE is created as a unique mode of response of the subauroral magnetosphere−ionosphere−thermosphere coupling system. STEVE, SAR arcs, and proton auroras, the three major types of subauroral emissions, require energetic particle injections to the pre-midnight inner magnetosphere and interaction with cold plasma. However, it is not understood why they occur at different times and why they can co-exist and transition from one to another. Strong electron injections into the pre-midnight sector are suggested to be important for driving intense subauroral ion drifts (SAID). A system-level understanding of how the magnetosphere creates distinct injection features, drives subauroral flows, and disturbs the thermosphere to create optical emissions is required to address the key questions about STEVE. The ionosphere−thermosphere modeling that considers the extreme velocity and heating should be conducted to answer what chemical and dynamical processes occur and how much the STEVE luminosity can be explained. Citizen scientist photographs and scientific instruments reveal the evolution of fine-scale structures of STEVE and their connection to the picket fence. Photographs also show the undulation of STEVE and the localized picket fence. High-resolution observations are required to resolve fine-scale structures of STEVE and the picket fence, and such observations are important to understand underlying processes in the ionosphere and thermosphere.