Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, California 90095-1565, USA.
Laboratory for Atmospheric and Space Research, University of Colorado, Boulder, Colorado 80303-7814, USA.
Nature. 2013 Dec 19;504(7480):411-4. doi: 10.1038/nature12889.
Recent analysis of satellite data obtained during the 9 October 2012 geomagnetic storm identified the development of peaks in electron phase space density, which are compelling evidence for local electron acceleration in the heart of the outer radiation belt, but are inconsistent with acceleration by inward radial diffusive transport. However, the precise physical mechanism responsible for the acceleration on 9 October was not identified. Previous modelling has indicated that a magnetospheric electromagnetic emission known as chorus could be a potential candidate for local electron acceleration, but a definitive resolution of the importance of chorus for radiation-belt acceleration was not possible because of limitations in the energy range and resolution of previous electron observations and the lack of a dynamic global wave model. Here we report high-resolution electron observations obtained during the 9 October storm and demonstrate, using a two-dimensional simulation performed with a recently developed time-varying data-driven model, that chorus scattering explains the temporal evolution of both the energy and angular distribution of the observed relativistic electron flux increase. Our detailed modelling demonstrates the remarkable efficiency of wave acceleration in the Earth's outer radiation belt, and the results presented have potential application to Jupiter, Saturn and other magnetized astrophysical objects.
最近对 2012 年 10 月 9 日地磁暴期间获取的卫星数据进行的分析确定了电子相位空间密度峰值的发展，这是在外辐射带中心局部电子加速的有力证据，但与向内的径向扩散输运加速不一致。然而，对于 9 日发生的加速的精确物理机制仍未确定。先前的建模表明，一种被称为哨声的磁层电磁辐射可能是局部电子加速的潜在候选者，但由于先前电子观测的能量范围和分辨率的限制，以及缺乏动态全球波模型，因此无法确定哨声对辐射带加速的重要性。在这里，我们报告了在 9 日风暴期间获得的高分辨率电子观测结果，并使用最近开发的时变数据驱动模型进行的二维模拟证明，哨声散射解释了观测到的相对论电子通量增加的能量和角分布的时间演化。我们的详细建模展示了在地球外辐射带中波加速的惊人效率，并且所提出的结果可能适用于木星、土星和其他磁化天体物理物体。
