We report an observational study of magnetospheric field‐line resonances (FLRs) using multi‐point data from the Magnetospheric Multiscale (MMS) mission. We examine well‐defined FLR events in the frequency range ∼ 2‐10 mHz observed under disturbed solar wind conditions, such as high‐speed solar wind streams and solar wind pressure pulses. We focus on their azimuthal wave numbers (m‐numbers) and spatial variations of the wave frequencies; and compare their occurrence characteristics and wave properties for insights into their energy sources. Under disturbed solar wind conditions, we have found supporting observations for both external and internal energy sources for the generation of FLRs. The FLRs associated with different energy sources appear to have different wave characteristics. Although mode coupling is very common (i.e., waves generally have both toroidal and poloidal components with variable relative amplitudes), our observations show that solar wind disturbances directly drive low‐m, toroidal mode dominated FLRs, but internal energy sources are inferred for high‐m, poloidal mode dominated FLRs. The frequencies of the toroidal and poloidal waves have different spatial variations as a function of the L‐value. The frequency of the toroidal mode waves can change continuously with L while the frequency of poloidal waves exhibits discrete spatial structure along L.

中文翻译：

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太阳风扰动下场线共振的MMS观测

我们使用磁层多尺度（MMS）任务的多点数据报告了磁层磁力线共振（FLR）的观测研究。我们检查了在受干扰的太阳风条件下（例如高速太阳风流和太阳风压力脉冲）在2-10 mHz频率范围内观察到的明确定义的FLR事件。我们关注它们的方位角波数（m数）和波频率的空间变化。并比较它们的发生特征和波浪性质，以深入了解其能量来源。在太阳风的干扰条件下，我们发现对于内部和外部能源产生FLR的支持性观察。与不同能源相关的FLR似乎具有不同的波浪特征。尽管模式耦合非常普遍（例如，波浪通常同时具有相对振幅可变的环形和极向分量），我们的观察结果表明，太阳风扰动直接驱动了以低辐射，环形模式为主的FLR，但是推断出内部能量源是以高m，以极坐标模式为主的FLR。环形波和极向波的频率具有不同的空间变化，这是L值的函数。环形波的频率可以随着L连续变化，而极向波的频率则沿着L呈现离散的空间结构。环形波和极向波的频率具有不同的空间变化，这是L值的函数。环形波的频率可以随着L连续变化，而极向波的频率则沿着L呈现离散的空间结构。环形波和极向波的频率具有不同的空间变化，这是L值的函数。环形波的频率可以随着L连续变化，而极向波的频率则沿着L呈现离散的空间结构。