GEM: Self-Consistent Model for Regions of Downward Auroral Current

磁层和电离层之间的主要耦合是通过沿地球磁场流动的电流来完成的。向上的电流区域通常是由向下流动的电子引起的，这是许多卫星观测到的。相比之下，向下的电流区域通常包含向上流动的电子，这更难观察到。因此，我们对下行洋流区域的认识落后于对上行洋流区域的认识。这项研究将发展一个自洽的画面等离子体和磁场性质的向下极光电流区域。该结果将有助于更好地理解离子圆锥粒子分布、向下指向的电场和极低频/极低频湍流等特征。这项研究的理论基础将是把这个问题分解成两个独立但又相互关联的问题，它们的时间尺度截然不同。ELF/VLF湍流在毫秒的时间尺度上运行，而大尺度极光电流结构的演变在分钟到小时的时间尺度上发生。因此，可以在缓慢变化的背景分布的情况下确定自洽的高频频谱。

The primary coupling between the magnetosphere and the ionosphere is accomplished via electric currents flowing along the Earth's magnetic field. Upward current regions generally result from downward flowing electrons which have been observed with many satellites. In contrast, downward current regions generally involve upward flowing electrons that have been more difficult to observe. Thus our outstanding of the downward current regions has lagged behind our understanding of the upward current regions. This study will develop a self-consistent picture of the plasma and field properties of downward auroral current regions. The results will lead to a better understanding of such features as ion conic particle distributions, downward pointing electric fields and ELF/VLF turbulence. The theoretical underpinning of the study will be to break the problem into two separate but coupled problems with vastly different time scales. ELF/VLF turbulence operates on times scales of milliseconds, while the evolution of the large-scale auroral current structures takes place on time scales of minutes to hours. Thus a self-consistent high frequency spectrum can be determined in the context of a slowly evolving background distribution.