Collaborative Research: Self-Consistent Ring-Current Particle Transport Simulations

该项目旨在了解磁暴期间地球环电流的动态，并了解其对内磁层（IM）磁场结构的影响。虽然众所周知，环形电流的形成会导致内磁层的大磁场下降，但对磁暴期间内磁层磁场结构的全球变化尚未有充分全面的了解。这样的理解是非常必要的，因为IM磁场影响IM粒子的输运、充能和损失。实现这一目标的方法是应用磁场和静电自一致的动力学环电流模拟风暴事件，并将模拟结果与CAMMICE和MFE仪器等卫星仪器的原位粒子测量结果和IMAGE航天器的高能中性原子（ENA）图像进行比较。该项目将具体解决(a)不同地磁风暴的环电流及其磁特征的时空变化，(b)环电流的不对称性以及asi - h指数如何很好地表征这种不对称性，(c)环电流对Dst磁指数的实际贡献。(d)感应电场在磁暴主阶段减轻环电流粒子通电的量，以及（如果有的话）延长磁暴恢复阶段的量，以及(e)考虑到磁层等离子体压力和电离层电导（包括沉淀电子的影响）对粒子输运和损失的自一致静电场的影响。作为这项研究的一部分，将评估基于自一致模拟的环电流动力学模型如何很好地解释等离子体压力和电流密度分布（从离子通量测量推断）以及测量的磁和电强度。除了模拟风暴事件外，还将进行数值实验来阐明物理过程。环电流磁场的模拟和模拟/数据比较将有助于指导社区范围内的努力，以开发更现实的内磁层磁场模型，这是研究和空间天气应用所迫切需要的。

This project seeks to understand the dynamics of the Earth's ring current during magnetic storms and to understand its effects on the inner magnetospheric (IM) magnetic field structure. While it is well known that the formation of a ring current leads to large magnetic field depressions in the inner magnetosphere, there is not yet a sufficient comprehensive understanding of global variations in IM magnetic field structure during magnetic storms. Such an understanding is critically needed because the IM magnetic field affects IM particle transport, energization, and loss. The approach toward this objective is to apply magnetically and electrostatically self-consistent kinetic ring current simulations for storm events and to compare the simulation results with in-situ particle measurements from satellite instruments such as the CAMMICE and MFE instruments on and energetic neutral atom(ENA) images ENA images from the IMAGE spacecraft.The project will specifically address (a) the spatial and temporal variation of the ring current and its magnetic signature for different geomagnetic storms, (b) the asymmetry of the ring current and how well the ASY-H index characterizes such asymmetries, (c) the actual contribution of the ring current to the Dst magnetic index, (d) the amount that induced electric fields mitigate the energization of ring current particles during the main phase and (if at all) prolong the recovery phase of a magnetic storm, and (e) the effects of self-consistent electrostatic fields, by taking account of magnetospheric plasma pressure and ionospheric conductances (including effects of precipitating electrons) on particle transport and loss. As part of this research, an assessment of how well self-consistent simulation-based kinetic models of the ring current can account for plasma pressure and current density distributions (inferred from ion-flux measurements) and measured magnetic and electric intensities will be made. In addition to simulating storm events, numerical experiments will be made to elucidate the physical processes. The simulations and simulation/data comparisons of the ring-current magnetic field will help guide community-wide efforts toward developing more realistic models of the inner magnetospheric magnetic field that are critically needed for research and space weather applications.