夜侧极光的尺度大小依赖特征
Scale size-dependent characteristics of the nightside aurora
摘要：
我们已经确定的磁层电离层（M-I）耦合的时空特性，使用极光成像。一台地面全天成像仪测量557.7纳米极光发射，在固定位置进行长时间观测。我们报告了一个单一的夜侧极光事件（$\sim$ 22磁当地时间）之前的亚暴发病。为了确定的时空特性，我们进行了一个创新的分析的全天空成像电影（19分钟的持续时间，在3.31赫兹的图像），结合了二维空间快速傅立叶变换与时间相关性。我们发现一个规模大小依赖的变异性，最大的规模大小是稳定的时间尺度分钟，而小规模的大小是更多变的。当比较两个较小的时间间隔的不同类型的极光显示，我们发现他们的特点的变化。在事件的平均值的特性是在显着的协议与夜侧场向电流的时空特征在中度干扰的时间。因此，两个不同的电动力学参数的M-I耦合表现出类似的行为。这为系统行为的主张提供了独立的支持，该系统行为使用可重复的解决方案将能量和动量从磁层转移到电离层。
英文摘要：
We have determined the spatiotemporal characteristics of the magnetosphere-ionosphere (M-I) coupling using auroral imaging. Observations at fixed positions for an extended period of time are provided by a ground-based all-sky imager measuring the 557.7 nm auroral emissions. We report on a single event of nightside aurora ($\sim$22 magnetic local time) preceding a substorm onset. To determine the spatiotemporal characteristics, we perform an innovative analysis of an all-sky imager movie (19 min duration, images at 3.31 Hz) that combines a two-dimensional spatial fast Fourier transform with a temporal correlation. We find a scale size-dependent variability where the largest scale sizes are stable on timescales of minutes while the small scale sizes are more variable. When comparing two smaller time intervals of different types of auroral displays, we find a variation in their characteristics. The characteristics averaged over the event are in remarkable agreement with the spatiotemporal characteristics of the nightside field-aligned currents during moderately disturbed times. Thus, two different electrodynamical parameters of the M-I coupling show similar behavior. This gives independent support to the claim of a system behavior that uses repeatable solutions to transfer energy and momentum from the magnetosphere to the ionosphere.
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