Relativistic Electron Precipitation Near Midnight: Drivers, Distribution, and Properties
Relativistic Electron Precipitation Near Midnight: Drivers, Distribution, and Properties
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DOI：
10.1029/2021ja030111
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发表时间：
2022-01
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影响因子：
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通讯作者：
L. Capannolo;W. Li;R. Millan;D. Smith;Nithin Sivadas;J. Sample;S. Shekhar
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文献类型：
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作者：
L. Capannolo;W. Li;R. Millan;D. Smith;Nithin Sivadas;J. Sample;S. Shekhar
我们分析的驱动程序，分布和相对论电子降水（REP）的性质检测到午夜附近的极轨环境卫星（POES）和气象业务（MetOp）卫星，了解辐射带损失和夜侧大气能量输入的关键。REP是由波粒相互作用（外辐射带内的孤立降水）或电流片散射（CSS;能量分散的降水）或两者的组合驱动的。我们评估了识别出的REP事件的L-MLT分布，其中只有一个过程明显地驱动了降水（午夜附近REP的10%）。我们表明，这两种机制共存，并在广泛的L-壳层范围内驱动沉淀（4-7）。然而，在L7也观察到波驱动REP。此外，我们估计磁尾拉伸在每个REP事件使用的磁场观测地球同步业务环境卫星（GOES）。波粒相互作用和CSS驱动的REP都与拉伸的磁尾有关，尽管CSS驱动的REP可能会显示出更明显的拉伸。波浪驱动的REP事件局限于L壳层，并且经常发生在<0.3 L的空间尺度上。使用质子沉淀（在波驱动REP期间由POES/MetOp观察到）作为电磁离子回旋（EMIC）波活动的代理，或在共轭事件位置处的波观测（来自GOES和货车艾伦探针），我们发现约73%的波驱动REP事件与EMIC波相关。
We analyze the drivers, distribution, and properties of the relativistic electron precipitation (REP) detected near midnight by the Polar Orbiting Environmental Satellites (POES) and Meteorological Operational (MetOp) satellites, critical for understanding radiation belt losses and nightside atmospheric energy input. REP is either driven by wave‐particle interactions (isolated precipitation within the outer radiation belt), or current sheet scattering (CSS; precipitation with energy dispersion), or a combination of the two. We evaluate the L‐MLT distribution for the identified REP events in which only one process evidently drove the precipitation (∼10% of the REP near midnight). We show that the two mechanisms coexist and drive precipitation in a broad L‐shell range (4–7). However, wave‐driven REP was also observed at L 7. Moreover, we estimate the magnetotail stretching during each REP event using the magnetic field observations from the Geostationary Operational Environmental Satellite (GOES). Both wave‐particle interactions and CSS drive REP in association with a stretched magnetotail, although CSS‐driven REP potentially shows more pronounced stretching. Wave‐driven REP events are localized in L shell and often occur on spatial scales of <0.3 L. Using either proton precipitation (observed by POES/MetOp during wave‐driven REP) as a proxy for electromagnetic ion cyclotron (EMIC) wave activity or wave observations (from GOES and the Van Allen Probes) at the conjugate event location, we find that ∼73% wave‐driven REP events are associated with EMIC waves.