Bicoherence Analysis of Oxygen Ion Cyclotron Harmonic Waves Observed by Van Allen Probes
Bicoherence Analysis of Oxygen Ion Cyclotron Harmonic Waves Observed by Van Allen Probes
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DOI：
10.1029/2023gl105958
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发表时间：
2023-12
影响因子：
5.2
通讯作者：
Yan Wang;Kaijun Liu;Fei Yao;Ying Xiong
中科院分区：
文献类型：
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作者：
Yan Wang;Kaijun Liu;Fei Yao;Ying Xiong
对货车艾伦探针观测到的氧离子回旋谐波进行了统计分析。虽然OCH波和所谓的电磁离子回旋谐波在观测中具有不可区分的光谱特性，但它们被认为是由不同的机制激发的，后者被认为是由非线性波-波耦合引起的。我们的结果表明，大多数OCH波事件具有较小的双相干指数，因此它们不太可能由波-波耦合激发。结果是没有太大的影响，在双相干分析中的参数选择，虽然增加子区间长度和/或减少子区间重叠增加的机会，得到大的双相干指数值。此外，对两个具有大双相干指数的特殊事件的检查表明，观察到的不同波分量之间的相位关系与波-波耦合的预期不一致。无法令人信服地证实事件是通过波-波耦合产生的。
Bicoherence analysis is statistically performed for the oxygen ion cyclotron harmonic (OCH) waves observed by Van Allen Probes. While OCH waves and so‐called electromagnetic ion cyclotron harmonics have indistinguishable spectral characteristics in observation, they are believed to be excited by different mechanisms with the latter being suggested to arise from nonlinear wave‐wave coupling. Our result reveals that most of the OCH wave events have small bicoherence indices, so they are unlikely excited by wave‐wave coupling. The result is not much affected by the parameter choice in the bicoherence analysis, although increasing the subinterval length and/or reducing the subinterval overlap increases the chance of getting large bicoherence index values. Furthermore, the examination of two special events with large bicoherence indices shows that the observed phase relationship among different wave components does not align with the expectation from wave‐wave coupling. The events cannot be convincingly confirmed to be generated through wave‐wave coupling.