AGS-PRF: Dayside Field Aligned Currents and Energy Deposition: The Effect of Magnetospheric Structure and Ionospheric Conductivity

这个项目将研究地球磁层中强烈的日侧磁场定向电流(FAC)。当行星际磁场主要位于黄道面时，这些强烈的FAC就会发生。特别是，该项目将审查当垂直于黄道面的磁场分量向上(正IMF BZ)时这些电流的发生情况。这些FAC已被证明与电离层焦耳加热和坡印亭通量的极端水平有关，这导致电离层等离子体上涌和异常的热层密度增强。场向电流强度图、电离层焦耳加热图和极帽电势图将与磁层场线拓扑以及上游和磁鞘太阳风驱动条件和等离子体参数有关。将讨论以下科学问题：(1)这些电流的大小如何受磁层的磁拓扑影响？(2)电流的来源是在日侧磁层顶合并还是由于弓形激波的表面电流？(3)电离层的导电性(包括季节性效应)如何影响FAC、焦耳加热和Poynting通量的大小。这些问题将利用各种陆基和天基数据加以解决。本项目将解决的问题将使人们对在通常被认为是磁性安静的条件下发生的重要空间天气影响有新的了解。特别是，该项目将提高我们对这些强洋流对增强热层上升流的影响的理解，热层上升流导致卫星阻力增加。这项研究将主要由一名新近毕业的博士进行。

This project will examine intense dayside field-aligned currents(FACs) in Earth's magnetosphere. These intense FACS occur when the interplanetary magnetic field is strong a lies primarily in the ecliptic plane. In particular the project will examine the occurrence of these currents when the component of the magnetic field perpendicular to the ecliptic plane is upward (positive IMF Bz). These FACs have been shown to be associated with extreme levels of ionospheric Joule heating and Poynting flux, which leads to upwelling of ionospheric plasma and anomalous thermospheric density enhancements. Maps of field-aligned current intensity, ionospheric joule heating, and the polar cap potential pattern will be related to the magnetospheric field-line topology as well as upstream and magnetosheath solar wind driving conditions and plasma parameters. The following scientific questions will be addressed: (1) how is the magnitude of these currents affected by the magnetic topology of the magnetosphere? (2) is the source of the current magnetic merging at the dayside magnetopause or is it due to surface currents at the bow shock? (3) how does the conductivity of the ionosphere (including seasonal effects) affect the magnitude of the FACs, the Joule heating and the Poynting flux. These questions will be addressed using a large variety of ground-based and space-based data.The questions that will be addressed in this project will provide new understanding of important space weather effects that take place under conditions that are generally considered to be magnetically quiet. In particular the project will improve our understanding of the effects these strong currents have on enhancing thermospheric upwelling, which leads to increased satellite drag. The research will be primarily conducted by a recent PhD graduate.