Phase Coherence in Elemental Auroral Structure

基本极光结构中的相位相干性

• 批准号: 0852850
• 负责人: Joshua Semeter
• 金额: $ 26.01万
• 依托单位: Trustees of Boston University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-10-01 至 2012-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0852850&HistoricalAwards=false
• 关键词: Phase; Coherence; Elemental; Auroral; Structure

This is a three-year research project concerning the physics of dynamic discrete aurora, generally associated with geomagnetic substorms and storms. The specific overarching goal is to determine the extent to which elemental (sub-100-meter) structure in the discrete aurora is consistent with field and particle configurations of dispersive Alfven waves. The work will utilize two observational innovations. The first is the use a new narrow-field high-speed imaging system based on Electron Multiplying CCD (EMCCD) technology. This will make it possible to quantify phase coherence in fine-scale auroral structure in space and time at unprecedented resolution. Additional data for this research will be provided by a new permanent EMCCD imaging system that is being established at Poker Flat. The second innovation is the use of the high-speed steering capabilities of the Poker Flat IS radar (PFISR) to identify regions of coherent scatter associated with filamentary (Alfvenic) current systems at 1 s cadence. These local measurements will be placed in a global-scale context using multi-station observations from the THEMIS all-sky camera array, as well as measurements of the auroral power source from the THEMIS satellites themselves. A comprehensive program combining unique observational capabilities, the development of sophisticated new analysis tools, modeling, and theoretical interpretation will be conducted to address three specific questions: 1) Can wave dispersion account for spatiotemporal variability in observed precipitation patterns? 2) Is there evidence for multiple reflections (resonant modes), or can all fine-scale structure be accounted for by direct absorption of wave energy? 3) Is more than one fundamental mechanism required to account for all elemental structure in the aurora? The project has significant broader impacts. Scientifically, the processes investigated in this project are fundamental to our general understanding of multi-scale energy balance in the high-latitude magnetosphere. The processes are also not unique to the terrestrial magnetospheric plasma; the insight gained in this research will inform our general understanding of energy transfer in cosmic and laboratory plasmas. Educationally, it will contribute to the training of two PhD scientists in the areas of auroral physics and image processing. Finally, the work will produce fascinating imagery of the aurora that will be utilized in public outreach efforts and shared widely over the web.

这是一个为期三年的研究项目，涉及动态离散极光的物理学，通常与地磁亚暴和磁暴有关。具体的首要目标是确定离散极光中的元素（低于100米）结构与色散阿尔文波的场和粒子配置一致的程度。 这项工作将利用两个观测创新。一是采用了基于电子倍增CCD（EMCCD）技术的新型窄视场高速成像系统。这将使得有可能以前所未有的分辨率量化空间和时间上精细尺度极光结构的相位相干性。这项研究的额外数据将由一个新的永久性EMCCD成像系统提供，该系统正在扑克平台上建立。第二个创新是使用高速转向能力的扑克牌平面IS雷达（PFISR），以确定相关的相干散射区域与1秒的节奏（Alfvenic）电流系统。将利用THEMIS全天空照相机阵列的多站观测以及THEMIS卫星本身对极光电源的测量，将这些局部测量置于全球范围内。 一个综合的计划，结合独特的观测能力，先进的新的分析工具，建模和理论解释的发展将进行解决三个具体问题：1）波色散可以解释观测到的降水模式的时空变化？2)是否有多次反射（共振模式）的证据，或者所有的精细尺度结构都可以通过波能的直接吸收来解释？3)是否需要一种以上的基本机制来解释极光中的所有元素结构？ 该项目具有重大的广泛影响。从科学角度讲，该项目中研究的过程对于我们对高纬度磁层多尺度能量平衡的一般理解至关重要。这些过程也不是地球磁层等离子体所独有的;这项研究中获得的见解将为我们对宇宙和实验室等离子体中能量传递的总体理解提供信息。在教育方面，它将有助于培训极光物理学和图像处理领域的两名博士科学家。 最后，这项工作将产生迷人的极光图像，这些图像将用于公共宣传工作，并在网络上广泛分享。