Electrodynamics and energy characteristics of aurora at high resolution by optical methods
Electrodynamics and energy characteristics of aurora at high resolution by optical methods
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DOI：
10.1002/2016ja022446
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发表时间：
2016-06
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影响因子：
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通讯作者：
H. Dahlgren;B. Lanchester;N. Ivchenko;D. Whiter
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文献类型：
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作者：
H. Dahlgren;B. Lanchester;N. Ivchenko;D. Whiter
技术进步导致光学探测器的灵敏度提高，揭示了极光包含丰富的动态和薄的发光结构，但结构发射的来源还没有完全了解。此外，高分辨率雷达数据表明，薄的极光弧可以与高度变化和大电场相关，但极光细丝电动力学的详细图像还不完整。极光结构和动力学（ASK）仪器是一种最先进的地面仪器，旨在通过使用三个电子倍增CCD并行用于三个不同的窄光谱区域，以非常高的空间和时间分辨率研究这些最小的极光特征。ASK是专门设计来利用一种新的光学技术来确定电离层电场。通过在732 nm处对长寿命的O+线进行成像，可以追踪该区域的等离子体流动，并且由于等离子体运动由电场控制，因此可以以前所未有的分辨率估计场强和方向。该方法是研究极光细暗条周围详细电动力学和电流系统的有力工具。另外两台ASK相机通过即时发射成像提供有关降水的信息，两种发射的发射亮度比以及离子化学建模用于提供有关降水电子的能量和能量通量的信息。在本文中，我们讨论了这些测量技术，并给出了一些例子，说明它们如何用于揭示极光中精细结构的性质和来源。
Technological advances leading to improved sensitivity of optical detectors have revealed that aurora contains a richness of dynamic and thin filamentary structures, but the source of the structured emissions is not fully understood. In addition, high‐resolution radar data have indicated that thin auroral arcs can be correlated with highly varying and large electric fields, but the detailed picture of the electrodynamics of auroral filaments is yet incomplete. The Auroral Structure and Kinetics (ASK) instrument is a state‐of‐the‐art ground‐based instrument designed to investigate these smallest auroral features at very high spatial and temporal resolution, by using three electron multiplying CCDs in parallel for three different narrow spectral regions. ASK is specifically designed to utilize a new optical technique to determine the ionospheric electric fields. By imaging the long‐lived O+ line at 732 nm, the plasma flow in the region can be traced, and since the plasma motion is controlled by the electric field, the field strength and direction can be estimated at unprecedented resolution. The method is a powerful tool to investigate the detailed electrodynamics and current systems around the thin auroral filaments. The two other ASK cameras provide information on the precipitation by imaging prompt emissions, and the emission brightness ratio of the two emissions, together with ion chemistry modeling, is used to give information on the energy and energy flux of the precipitating electrons. In this paper, we discuss these measuring techniques and give a few examples of how they are used to reveal the nature and source of fine‐scale structuring in the aurora.