ULF‐Modulation of Whistler‐Mode Waves in the Inner Magnetosphere During Solar Wind Compression
ULF‐Modulation of Whistler‐Mode Waves in the Inner Magnetosphere During Solar Wind Compression
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DOI：
10.1029/2021ja029353
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发表时间：
2021-08
期刊：
影响因子：
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通讯作者：
Xiongjun Shang;Si Liu;Lunjin Chen;Zhonglei Gao;Geng Wang;Qian He;Tong Li;F. Xiao
中科院分区：
文献类型：
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作者：
Xiongjun Shang;Si Liu;Lunjin Chen;Zhonglei Gao;Geng Wang;Qian He;Tong Li;F. Xiao
太阳风在地球磁层动力学中起着重要的作用，包括粒子布居和等离子体波的产生。在这里，我们报告了一个有趣的事件，即超低频（ULF）波在太阳风压缩后立即增强，压缩模式ULF波随后调制哨声模式波的强度和能流方向。利用货车艾伦探测器在正午扇区L = 5.6附近观测到了准周期哨声波包。生长率计算表明，压缩模式的超低频波可以调制哨声模式的波强度通过调制高能电子的各向异性。此外，波能通量的方向被观察到在赤道之间交替向北和向南，这可能是因为强烈的ULF波周期性地改变波源区域相对于航天器的相对方向。目前的结果提供了一系列观测证据，说明在太阳风动压增强期间，内磁层中哨声模波的产生和传播如何受到ULF波的影响。
The solar wind plays important roles in terrestrial magnetosphere dynamics, including the particle population and plasma wave generation. Here, we report an interesting event that ultralow frequency (ULF) waves are enhanced right after solar wind compression and the compressional mode ULF wave subsequently modulates both the intensity and energy flux direction of whistler‐mode waves. Quasi‐periodic whistler‐mode wave packets are observed around L = 5.6 at noon sector by Van Allen Probes. Growth rate calculation demonstrates that the compressional mode ULF wave can modulate the whistler‐mode wave intensity by modulating the energetic electron anisotropy. Moreover, the direction of wave energy flux is observed to alternate between northward and southward at equator, which is probably because the intense ULF waves periodically alter the relative direction of the wave source region with respect to the spacecraft. The current results provide a chain of observational evidences to illustrate how the generation and propagation of whistler‐mode waves in the inner magnetosphere are affected by ULF waves during the solar wind dynamic pressure enhancement.