Relation Between Shock‐Related Impulse and Subsequent ULF Wave in the Earth's Magnetosphere
Relation Between Shock‐Related Impulse and Subsequent ULF Wave in the Earth's Magnetosphere
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DOI：
10.1029/2020gl090027
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发表时间：
2020-11
影响因子：
5.2
通讯作者：
Dianjun Zhang;Wenlong Liu;Xinlin Li;T. Sarris;YongFu Wang;Chao Xiao;Zhao Zhang;J. Wygant
中科院分区：
文献类型：
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作者：
Dianjun Zhang;Wenlong Liu;Xinlin Li;T. Sarris;YongFu Wang;Chao Xiao;Zhao Zhang;J. Wygant
利用货车艾伦探针测量，通过研究第一个脉冲和随后的共振超低频（ULF）波之间的关系，研究了地球磁层中行星际冲击感应电场脉冲产生的Pc 4 - 5超低频（ULF）波。在昼侧，第一脉冲的相关时间尺度与局部阿尔文速度的相关性比与局部本征频率的相关性更好，这意味着第一脉冲的时间尺度更可能与快模波传播有关，而不是与局部场线共振有关。在51个事件中，只有20个事件在第一次脉冲后产生窄带极向ULF波，这表明在脉冲等效频率尺度与局部本征频率匹配的位置产生ULF波的机会更高。结果表明，只要冲击脉冲具有足够大的振幅，且其频率与磁层本征频率相匹配，就可以在磁层中激发出与冲击相关的超低频波。
The generation of Pc4‐5 ultralow frequency (ULF) waves after interplanetary shock‐induced electric field impulses in the Earth's magnetosphere is studied using Van Allen Probes measurements by investigating the relationship between the first impulses and subsequent resonant ULF waves. In the dayside, the relevant time scales of the first impulse is correlated better with local Alfvén speed than with local eigenfrequency, implying that the temporal scale of the first impulse is more likely related to fast‐mode wave propagation rather than local field line resonance. There are only 20 out of 51 events with narrow‐band poloidal ULF waves induced after the first impulse, showing a higher chance for ULF wave generation at the locations where the impulse equivalent frequency scale matches the local eigenfrequency. It is suggested that the shock‐related ULF wave can be excited in the magnetosphere on condition that shock‐induced impulse has large enough amplitude with its frequency matching the local eigenfrequency.