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The Combined Influence of Lower Band Chorus and ULF Waves on Radiation Belt Electron Fluxes at Individual L‐Shells
Journal of Geophysical Research: Space Physics ( IF 2.8 ) Pub Date : 2021-04-19 , DOI: 10.1029/2020ja028755
Laura E. Simms 1 , Mark J. Engebretson 1 , Craig J. Rodger 2 , Stavros Dimitrakoudis 3 , Ian. R. Mann 3 , Peter J. Chi 4
Affiliation  

We investigate the timing and relative influence of VLF in the chorus frequency range observed by the DEMETER spacecraft and ULF wave activity from ground stations on daily changes in electron flux (0.23 to over 2.9 MeV) observed by the HEO‐3 spacecraft. At each L‐shell, we use multiple regression to investigate the effects of each wave type and each daily lag independent of the others. We find that reduction and enhancement of electrons occur at different timescales. Chorus power spectral density and ULF wave power are associated with immediate electron decreases on the same day but with flux enhancement 1–2 days later. ULF is nearly always more influential than chorus on both increases and decreases of flux, although chorus is often a significant factor. There was virtually no difference in correlations of ULF Pc3, Pc4, or Pc5 with electron flux. A synergistic interaction between chorus and ULF waves means that enhancement is most effective when both waves are present, pointing to a two‐step process where local acceleration by chorus waves first energizes electrons which are then brought to even higher energies by inward radial diffusion due to ULF waves. However, decreases in flux due to these waves act additively. Chorus and ULF waves combined are most effective at describing changes in electron flux at >1.5 MeV. At lower L (2–3), correlations between ULF and VLF (likely hiss) with electron flux were low. The most successful models, over L = 4–6, explained up to 47.1% of the variation in the data.

中文翻译:

低频带合唱和ULF波对单个L壳处辐射带电子通量的综合影响

我们研究了DEMETER航天器观测到的VLF在合唱频率范围内的时间和相对影响以及地面站的ULF波活动对HEO-3航天器观测到的电子通量的每日变化(0.23到2.9 MeV以上)的相对影响。在每个L‐壳,我们使用多元回归来研究每种波动类型和每个每日滞后独立于其他波动的影响。我们发现电子的减少和增强发生在不同的时间尺度上。合唱功率谱密度和ULF波功率与同一天的立即电子减少有关,但与1-2天后的通量增加有关。尽管合唱通常是一个重要因素,但在通量的增加和减少方面,ULF几乎总是比合唱更有影响力。ULF Pc3,Pc4或Pc5与电子通量的相关性实际上没有差异。合唱和ULF波浪之间的协同相互作用意味着,当两个波浪都存在时,增强效果最有效,指出了一个两步过程,其中合唱波的局部加速度首先使电子通电,然后由于ULF波的向内径向扩散将电子带到更高的能量。但是,由于这些波而导致的磁通量下降会相加作用。组合的合唱和ULF波最有效地描述了> 1.5 MeV时电子通量的变化。在较低L(2-3),ULF和VLF(可能是嘶嘶声)与电子通量之间的相关性很低。在L  = 4–6上,最成功的模型可以解释多达47.1%的数据变化。
更新日期:2021-05-03
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