Electron Precipitation Observed by ELFIN Using Proton Precipitation as a Proxy for Electromagnetic Ion Cyclotron (EMIC) Waves
Electron Precipitation Observed by ELFIN Using Proton Precipitation as a Proxy for Electromagnetic Ion Cyclotron (EMIC) Waves
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DOI：
10.1029/2023gl103519
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发表时间：
2023-09
影响因子：
5.2
通讯作者：
L. Capannolo;Wen Li;Qianli Ma;M. Qin;X. Shen;V. Angelopoulos;A. Artemyev;Xiao‐jia Zhang;M. Hanzelka
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文献类型：
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作者：
L. Capannolo;Wen Li;Qianli Ma;M. Qin;X. Shen;V. Angelopoulos;A. Artemyev;Xiao‐jia Zhang;M. Hanzelka
电磁离子回旋加速器(EMIC)波可以驱动辐射带耗尽，低地球轨道卫星可以探测到由此产生的电子和质子沉淀。ELFIN(电子损失和场调查)CubeSats提供了一个极好的机会来研究EMIC驱动的电子沉淀的性质，其能量和俯仰角分辨率比以前允许的要高得多。我们从ELIN观测中收集了EMIC驱动的电子降水事件，并利用POES(极轨环境卫星)搜索附近的10S-100SkeV质子降水作为EMIC波活动的替代。电子沉淀主要发生在定域径向尺度(∼0.3MLT L)上，超过15-24MLT和5-8个L壳层，在∼MeV能量下较强，向下到∼100-200keV较弱。此外，观测到的损失锥俯仰角分布与≳250keV(随着能量增加而填充更多的损失锥)下的拟线性预测一致，但需要额外的机制来解释观测到的低能降水。
Electromagnetic ion cyclotron (EMIC) waves can drive radiation belt depletion and Low‐Earth Orbit satellites can detect the resulting electron and proton precipitation. The ELFIN (Electron Losses and Fields InvestigatioN) CubeSats provide an excellent opportunity to study the properties of EMIC‐driven electron precipitation with much higher energy and pitch‐angle resolution than previously allowed. We collect EMIC‐driven electron precipitation events from ELFIN observations and use POES (Polar Orbiting Environmental Satellites) to search for 10s–100s keV proton precipitation nearby as a proxy of EMIC wave activity. Electron precipitation mainly occurs on localized radial scales (∼0.3 L), over 15–24 MLT and 5–8 L shells, stronger at ∼MeV energies and weaker down to ∼100–200 keV. Additionally, the observed loss cone pitch‐angle distribution agrees with quasilinear predictions at ≳250 keV (more filled loss cone with increasing energy), while additional mechanisms are needed to explain the observed low‐energy precipitation.