Multipoint Observations of Quasiperiodic Emission Intensification and Effects on Energetic Electron Precipitation
Multipoint Observations of Quasiperiodic Emission Intensification and Effects on Energetic Electron Precipitation
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DOI：
10.1029/2020ja028484
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发表时间：
2021-01
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通讯作者：
Jinxing Li;J. Bortnik;Q. Ma;Wen Li;X. Shen;Y. Nishimura;X. An;S. Thaller;A. Breneman;J. Wygant;W. Kurth;G. Hospodarsky;D. Hartley;G. Reeves;H. Funsten;J. Blake;H. Spence;D. Baker
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作者：
Jinxing Li;J. Bortnik;Q. Ma;Wen Li;X. Shen;Y. Nishimura;X. An;S. Thaller;A. Breneman;J. Wygant;W. Kurth;G. Hospodarsky;D. Hartley;G. Reeves;H. Funsten;J. Blake;H. Spence;D. Baker
两个Van Allen探测器同时记录了持续3小时的相干调制准周期(QP)发射。两颗卫星位置的磁场脉动显示出很大的差异，它们的频率在大部分时间接近但不完全匹配QP发射的重复频率，这表明这些相干QP发射可能来自一个共同的源，然后在磁层的大范围内传播。QP发射通过局域各向异性电子分布放大，其大尺度幅度受等离子体密度的调制。对这一事件的一种新的观察是，QP发射以上频率的和声波与QP发射显示出很强的相关性。当QP辐射达到峰值频率时，这些合唱波变得更加强烈。这表明，在某些情况下，胚胎QP的排放可能对其自身的强化以及合唱波至关重要。一颗低地球轨道的POES卫星结合范艾伦探测器观测到了增强的高能电子沉淀，提供了QP发射将高能电子沉淀到大气中的直接证据。我们的拟线性扩散模拟结果定量地证实了这一假设。
The two Van Allen Probes simultaneously recorded a coherently modulated quasiperiodic (QP) emission that persisted for 3 h. The magnetic field pulsation at the locations of the two satellites showed a substantial difference, and their frequencies were close to but did not exactly match the repetition frequency of QP emissions for most of the time, suggesting that those coherent QP emissions probably originated from a common source, which then propagated over a broad area in the magnetosphere. The QP emissions were amplified by local anisotropic electron distributions, and their large‐scale amplitudes were modulated by the plasma density. A novel observation of this event is that chorus waves at frequencies above QP emissions exhibit a strong correlation with QP emissions. Those chorus waves intensified when the QP emissions reach their peak frequency. This indicates that embryonic QP emissions may be critical for its own intensification as well as chorus waves under certain circumstances. A Low‐Earth‐Orbit POES satellite observed enhanced energetic electron precipitation in conjunction with the Van Allen Probes, providing direct evidence that QP emissions precipitate energetic electrons into the atmosphere. This scenario is quantitatively confirmed by our quasilinear diffusion simulation results.