Relativistic Electron Precipitation by EMIC Waves: Importance of Nonlinear Resonant Effects
Relativistic Electron Precipitation by EMIC Waves: Importance of Nonlinear Resonant Effects
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DOI：
10.1029/2022gl099994
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发表时间：
2022-05
影响因子：
5.2
通讯作者：
V. Grach;A. Artemyev;A. Demekhov;Xiao‐jia Zhang;J. Bortnik;V. Angelopoulos;R. Nakamura;E. Tsai;C. Wilkins;O. Roberts
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文献类型：
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作者：
V. Grach;A. Artemyev;A. Demekhov;Xiao‐jia Zhang;J. Bortnik;V. Angelopoulos;R. Nakamura;E. Tsai;C. Wilkins;O. Roberts
地球辐射带中的相对论电子损失通常归因于电磁波的电子共振散射。这种散射的最重要的波模式之一是电磁离子回旋（EMIC）模式。在准线性扩散框架内，相对论电子与EMIC波的回旋共振导致非常快速的电子沉淀到大气中。然而，波的强度往往超过非线性共振相互作用的阈值，这种强烈的EMIC波已被证明运输电子远离损失锥由于力聚束效应。在这项研究中，我们调查，如果这种运输可以阻止电子沉淀。我们结合了联合收割机试验粒子模拟、电子损失和场调查使命对EMIC驱动的电子沉淀的低空观测以及地基EMIC观测。通过比较模拟和观测结果，我们发现，尽管低俯仰角的电子被传输远离损失锥，但在较高俯仰角下的散射导致损失锥填充和电子沉淀。
Relativistic electron losses in Earth's radiation belts are usually attributed to electron resonant scattering by electromagnetic waves. One of the most important wave modes for such scattering is the electromagnetic ion cyclotron (EMIC) mode. Within the quasi‐linear diffusion framework, the cyclotron resonance of relativistic electrons with EMIC waves results in very fast electron precipitation to the atmosphere. However, wave intensities often exceed the threshold for nonlinear resonant interaction, and such intense EMIC waves have been shown to transport electrons away from the loss cone due to the force bunching effect. In this study we investigate if this transport can block electron precipitation. We combine test particle simulations, low‐altitude observations of EMIC‐driven electron precipitation by the Electron Losses and Fields Investigations mission, and ground‐based EMIC observations. Comparing simulations and observations, we show that, despite the low pitch‐angle electrons being transported away from the loss cone, the scattering at higher pitch angles results in the loss cone filling and electron precipitation.