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

AGS-PRF：日侧场对准电流和能量沉积：磁层结构和电离层电导率的影响

• 批准号: 1137755
• 负责人: Frederick Wilder
• 金额: $ 8.6万
• 依托单位: Wilder Frederick D
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-01-01 至 2013-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1137755&HistoricalAwards=false
• 关键词: AGS; PRF; Dayside; Field; Aligned

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.

该项目将研究地球磁层中强烈的昼侧场向电流（FACs）。 当行星际磁场很强，主要位于黄道面时，这些强烈的FACS就会发生。 特别是，该项目将检查这些电流的发生时，垂直于黄道面的磁场分量是向上的（正IMF Bz）。 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的上涌和异常的热层密度增强。场向电流强度、电离层焦耳加热和极冠电位模式的地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。 以下科学问题将被解决：（1）如何影响这些电流的磁层的磁拓扑结构的大小？(2)电流的来源是在向阳面磁层顶的磁合并，还是由于弓形激波的表面电流？(3)电离层的传导性（包括季节效应）如何影响FAC、焦耳加热和坡印亭通量的大小。 这些问题将使用大量各种地基和天基数据加以解决，本项目中将解决的问题将使人们对在通常被认为是磁静的条件下发生的重要空间气象影响有新的认识。 特别是，该项目将提高我们对这些强气流对增强热层上涌的影响的理解，热层上涌导致卫星阻力增加。 这项研究将主要由一名最近的博士毕业生进行。