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  = 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.

中文翻译：

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太阳风压缩期间内磁层中惠斯勒模式波的超低频调制

太阳风在地球磁层动力学中起着重要作用，包括粒子群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 波随后调制了惠斯勒模式波的强度和能量通量方向。在周围观察到准周期性的哨声模式波包 = 5.6 中午扇区，由 Van Allen Probes 提供。增长率计算表明，压缩模式超低频波可以通过调制高能电子各向异性来调制哨声模式波强度。此外，在赤道观测到波能通量的方向在北向和南向之间交替，这可能是因为强烈的超低频波周期性地改变了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，以说明在太阳风动态压力增强期间，超低频波如何影响内磁层中惠斯勒模式波的产生和传播。