GEM: Relative Locations of Auroral Breakups to Large-scale Field-aligned Currents

该项目将调查极光分裂事件相对于连接磁层和电离层的大规模电流系统的位置。这种大规模的场向电流框架是地球磁场和太阳风相互作用的结果。 这些通过极地电离层的场向电流的闭合是极光椭圆的原因。 与太阳风相互作用的另一个后果是地球夜面的磁场线极度拉伸，形成了一个延伸的磁尾。 拉伸增加，直到存储在磁场中的能量爆炸性地释放，拉伸减小。 在这段时间里，穿过磁尾的电流被中断，并通过高纬度电离层分流，形成亚暴电流楔。 这种拉伸-释放-恢复的循环被称为亚暴。 拉伸增加的间隔称为亚暴增长阶段;爆炸性能量释放是亚暴扩张阶段（或极光分裂）的一个要素。极光分裂开始于接近午夜的极光椭圆低纬度边缘的现有弧变亮。 随后是一个最初局部的明亮和快速变化的极光区域，随着时间的推移向西和向极地传播。 极光分裂被认为与亚暴流楔的上升流腿有关。 这项研究利用全球场向电流的卫星观测和极光和地磁场扰动的地面观测，回答了关于大规模电流系统和与极光分裂有关的扰动亚暴电流之间的联系的重要问题。 该项目的一个重要内容是新数据产品所带来的独特的全球视角。 该项目将产生广泛的影响。 包括高中理科学生和教师在内的暑期实习生将参与这项研究，接受自动识别极光解体候选人和其他研究方面的培训。 从长远来看，加深对地球附近爆炸性空间天气扰动的了解将提高对依赖技术的社会具有价值的预报能力，主要目标是确定极光破裂与全球磁层电流系统之间的关系。 该方法包括案例研究和极光解体的时间和位置相对于当前系统的统计相关性。 这项研究现在才成为可能，因为NSF-NASA AMPERE计划利用66颗商用铱通信卫星上现有的工程磁力计，以10分钟的节奏开发了场向电流的全球地图。 这些地图将与来自NSF-NASA-ESA支持的SuperMAG计划的地磁场扰动地面地图相结合，该计划是目前运营300多个地面磁力计的组织和国家机构的全球合作。 SuperMAG将这些观测结果转化为全球磁场扰动图和其他测量地磁活动水平的参数。 最后，将从分布在整个北美极地地区的20个THEMIS地面全天空成像仪（ASI）（一些台站由NSF资助）获得极光分解图像。

This project will investigate the locations of auroral breakup events with respect to the large-scale electric current system connecting the magnetosphere and ionosphere. This framework of large-scale field-aligned currents is created as a result of the interaction between the Earth's magnetic field and the solar wind. The closure of these field-aligned currents through the polar ionosphere is responsible for the auroral oval. Another consequence of the interaction with the solar wind is the extremely stretched magnetic field lines on the nightside of the Earth that form an extended magnetotail. The stretching increases until the energy stored in the magnetic fields is released explosively and the stretching decreases. During this time, the electric current across the magnetotail is disrupted and shunted through the high-latitude ionosphere forming the substorm current wedge. This stretching-release-recovery cycle is called a substorm. The interval during which the stretching increases is called the substorm growth phase; the explosive energy release is an element of the substorm expansion phase (or auroral breakup). The auroral breakup begins with a brightening of an existing arc near midnight close to the lower latitude edge of the auroral oval. This is followed by an initially localized region of bright and rapidly varying auroras that spreads westward and poleward with time. The auroral breakup is thought to be associated with the upward current leg of the substorm current wedge. This study answers important questions about the connection between the large-scale current systems and the disturbed substorm currents associated with the auroral breakup using satellite observations of global field-aligned electric currents and ground-based observations of auroras and geomagnetic field disturbances. An important element of this project is the unique global view enabled by new data products. The project will have significant broader impacts. Summer interns including high school science students and teachers will be involved in the research, receiving training on automatic identification of auroral break-up candidates and other aspects of the research. In the longer term, an increased understanding of explosive space weather disturbances in the vicinity of Earth will improve forecasting capabilities of value to a technology-dependent society.The primary objective is to determine how auroral breakups relate to the global magnetospheric current systems. The methodology consists of case studies and statistical correlations of auroral breakup timing and location relative to the current systems. This study is only now possible because of the groundbreaking development by the NSF-NASA AMPERE program of global maps of field-aligned currents on a ten-minute cadence utilizing existing engineering magnetometers onboard 66 commercial Iridium communications satellites. These maps will be combined with ground-based maps of geomagnetic field perturbations from the NSF-NASA-ESA supported SuperMAG Program, which is a worldwide collaboration of organizations and national agencies that currently operate more than 300 ground based magnetometers. SuperMAG turns these observations into global maps of magnetic field disturbances and other parameters that measure the level of geomagnetic activity. Finally, auroral breakup images will be obtained from 20 THEMIS ground-based All Sky Imagers (ASIs) distributed across the entire North American polar region (some stations funded by NSF).