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首页> 外文期刊>Journal of Geophysical Research, A. Space Physics: JGR >Observations and Simulations of Dropout Events and Flux Decays in October 2013: Comparing MEO Equatorial With LEO Polar Orbit
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Observations and Simulations of Dropout Events and Flux Decays in October 2013: Comparing MEO Equatorial With LEO Polar Orbit

机译：观测和模拟和辍学的事件通量衰减2013年10月:比较MEO赤道与狮子座极地轨道

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摘要

We compare ESA PROBA-V observations of electron flux at LEO with those from the NASA Van Allen Probes mostly at MEO for October 2013. Dropouts are visible at all energy during four storms from both satellites. Equatorially trapped electron fluxes are higher than at LEO by 10~2 (2.5 MeV). We observe a quite isotropic structure of the outer belt during quiet times, contrary to the inner belt, and pitch angle dependence of high energy injection. We find a very good overlap of the outer belt at MEO and LEO at ~0.5 MeV. We use test-particle simulations of the energetic electrons trapped in the terrestrial magnetic field to study the outer radiation belt electron flux changes during geomagnetic storms. We show that the Dst (Disturbance storm time) effect during the main phase of a geomagnetic storm results in a betatron mechanism causing outward radial drift and a deceleration of the electrons. This outward drift motion is energy independent, pitch angle-dependent, and represents a significant distance (~1 L-shell at L = 5 for moderate storms). At fixed L-shell, this causes a decay of the LEO precipitating flux (adiabatic outward motion), followed by a return to the normal state (adiabatic inward motion) during main and recovery phases. Dst effect, associated with magnetopause shadowing and radial diffusion can explain the main characteristics of outer radiation belt electron dropouts in October 2013. We also use Fokker-Planck simulations with event-driven diffusion coefficients at high temporal resolution, to distinguish instantaneous loss from the gradual scattering that depopulates the slot region and the outer belt after storms. Simulations reproduce the slot formation and the gradual loss in the outer belt. The typical energy dependence of these losses leads to the absence of scattering for relativistic and ultra-relativistic electrons in the outer belt, oppositely to dropouts.
机译：我们比较ESA PROBA-V观测电子通量在狮子座与NASA范-艾伦2013年10月在MEO探针主要。可见能源在四个风暴两个卫星。在狮子座通量高于10 ~ 2( 2.5兆电子伏)。结构的外皮带在安静的时候,与内部辐射带和螺旋角高能注入的依赖。很好的外皮带在MEO和重叠狮子座~ 0.5兆电子伏。被困在充满活力的电子地磁场研究外在辐射带电子通量变化地磁风暴。在主要扰动风暴时间效应结果在一个阶段的地磁风暴电子感应加速器机制导致径向向外漂移和电子的减速。漂移运动是能源独立angle-dependent,代表一个意义重大距离(~ 1 L层温和的L = 5风暴)。狮子座沉淀通量(绝热外运动),其次是恢复到正常状态(向内绝热运动)在主要和复苏阶段。磁层阴影和径向扩散解释外的主要特征2013年10月辐射带电子辍学。我们也使用福克尔普朗克模拟事件驱动的扩散系数高时间分辨率,区分瞬时从渐进的散射,使人口减少损失暴风雨后的槽区和外皮带。模拟槽形成和繁殖逐渐丧失外腰带。这些损失导致的能源依赖缺乏对相对论和散射ultra-relativistic电子外,在相反的辍学生。

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