Electron Lifetimes and Diffusion Rates Inferred From ELFIN Measurements at Low Altitude: First Results
Electron Lifetimes and Diffusion Rates Inferred From ELFIN Measurements at Low Altitude: First Results
复制标题
DOI：
10.1029/2021ja029757
复制
发表时间：
2021-11
期刊：
影响因子：
--
通讯作者：
D. Mourenas;A. Artemyev;X.‐J. Zhang;V. Angelopoulos;E. Tsai;C. Wilkins
中科院分区：
文献类型：
--
作者：
D. Mourenas;A. Artemyev;X.‐J. Zhang;V. Angelopoulos;E. Tsai;C. Wilkins
在辐射带中，预计进入大气的高能和相对论电子沉淀在长期内主要由哨声模式和电磁离子回旋波的准线性俯仰角散射控制。因此，统计电子寿命是在多年波统计的基础上从拟线性扩散理论推导出来的。然而，这种电子寿命统计拟线性模型与测量的电子寿命、捕获和沉淀电子通量的光谱以及从电子通量测量推断的波驱动扩散速率的完全一致性尚未得到详细验证。在本研究中，我们使用 2018 年 9 月在低地球轨道发射的电子损耗和场调查 (ELFIN) 任务立方体卫星的数据，对准线性扩散理论和观测到的电子通量变化进行比较。我们表明，统计理论寿命模型与根据大气反向散射校正后 ELFIN 测量的沉淀电子通量与俘获电子通量比率推断出的电子俯仰角扩散速率，以及与 ELFIN 在几天内独立测量的俘获电子通量衰减的时间尺度相当一致。目前的结果首次证明了俘获电子通量衰减的时间尺度、沉淀电子的俯仰角分布和波驱动电子损失的拟线性模型之间的广泛一致性，显示了这种由地磁活动参数化的统计电子寿命模型的可靠性，用于评估在不太受干扰的时期进入大气的电子沉淀。
In the radiation belts, energetic and relativistic electron precipitation into the atmosphere is expected to be mainly controlled over the long term by quasilinear pitch‐angle scattering by whistler‐mode and electromagnetic ion cyclotron waves. Accordingly, statistical electron lifetimes have been derived from quasilinear diffusion theory on the basis of multi‐year wave statistics. However, the full consistency of such statistical quasilinear models of electron lifetimes with both measured electron lifetimes, spectra of trapped and precipitated electron fluxes, and wave‐driven diffusion rates inferred from electron flux measurements, has not yet been verified in detail. In the present study, we use data from Electron Loss and Fields Investigation (ELFIN) mission CubeSats, launched in September 2018 in low Earth orbit, to carry out such comparisons between quasi‐linear diffusion theory and observed electron flux variations. We show that statistical theoretical lifetime models are in reasonable agreement with electron pitch‐angle diffusion rates inferred from the precipitated to trapped 100 keV electron flux ratio measured by ELFIN after correction for atmospheric backscatter, as well as with timescales of trapped electron flux decay independently measured over several days by ELFIN. The present results demonstrate for the first time a broad consistency between timescales of trapped electron flux decay, the pitch‐angle distribution of precipitated electrons, and quasilinear models of wave‐driven electron loss, showing the reliability of such statistical electron lifetime models parameterized by geomagnetic activity for evaluating electron precipitation into the atmosphere during not too disturbed periods.