Filamentary Currents and Alfvénic Vortices in the Inner Magnetosphere
Filamentary Currents and Alfvénic Vortices in the Inner Magnetosphere
复制标题
内磁层中的丝状电流和阿尔芬涡旋
DOI：
10.1029/2019gl086318
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发表时间：
2020
影响因子：
5.2
通讯作者：
D. N. Baker
中科院分区：
文献类型：
--
作者：
C. Chaston;J. Bonnell;J. Wygant;Geoff D. Reeves;D. N. Baker
我们表明，在地磁扰动期间，范艾伦探测器在内磁层中观察到的宽带低频阿芬尼场变化由多尺度电流片、电流丝、流切变和涡流组成。这些观测结果涉及 0.1 < fsc < 10 Hz 范围内的航天器框架频率 (fsc)，并对应于 0.1 ≲ λ/ρi ≲ 10 范围内的航天器上空平流结构（λ）。其中 ρi 是平均离子回转半径。电流和流量的拓扑是通过适用于平流结构解释的时域和频谱方法导出的。结果揭示了磁和对流非线性在活跃时期内磁层中普遍存在的宽带阿尔芬涨落产生中的作用。观测到的电流丝状和旋转涡度暗示了动力学尺度上的宽带阿尔夫尼场变化是如何驱动的，并支持内磁层中具有地球物理意义的粒子加速。
We show that broadband low‐frequency Alfvénic field variations observed in the inner‐magnetosphere from the Van Allen Probes during geomagnetically disturbed intervals are composed of multiscale current sheets, current filaments, flow shears, and vortices. These observations pertain to spacecraft frame frequencies (fsc) over the range 0.1 < fsc < 10 Hz and correspond to structure advected over the spacecraft on scales (λ) over the range 0.1 ≲ λ/ρi ≲ 10. where ρi is the average ion gyroradius. The topology of the current and flow is derived via time domain and spectral approaches adapted for the interpretation of advected structure. The results reveal the action of magnetic and convective nonlinearities in the generation of broadband Alfvénic fluctuations prevalent in the inner magnetosphere during active times. The observed current filamentation and rotational vorticity is suggestive of how broadband Alfvénic field variations on kinetic scales are driven and support geophysically significant particle acceleration in the inner magnetosphere.
影响因子：
5.2
作者：
Damiano, P. A.;Chaston, C. C.;Johnson, J. R.
通讯作者：
Johnson, J. R.