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

该项目将调查与连接磁层和电离层的大规模电流系统有关的极光分裂事件的位置。这种大规模场对齐电流的框架是由于地球磁场和太阳风之间的相互作用而产生的。通过极地电离层的这些场向电流的关闭是极光椭圆形的原因。与太阳风相互作用的另一个结果是，地球黑夜一侧的磁力线极其伸展，形成了一个延伸的磁尾。伸缩增加，直到储存在磁场中的能量被爆炸性释放，伸缩减小。在此期间，穿过磁尾的电流被破坏，并通过高纬度电离层分流，形成亚暴电流楔形。这种伸展-释放-恢复的循环被称为亚风暴。伸展增加的时间间隔称为亚暴增长阶段；爆炸能量释放是亚暴扩张阶段(或极光破裂)的一个要素。极光破裂始于接近午夜时靠近极光椭圆形较低纬度边缘的一条现有弧线变亮。紧随其后的是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扩散和向极地扩散。极光的解体被认为与亚风暴洋流楔形的向上洋流支路有关。这项研究通过对全球场向电流的卫星观测和对极光和地磁场扰动的地面观测，回答了有关大尺度电流系统与与极光分裂有关的扰动亚风暴电流之间的联系的重要问题。该项目的一个重要元素是由新数据产品实现的独特的全局视图。该项目将产生重大的更广泛的影响。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，接受关于自动识别极光分手候选者的培训，以及研究的其他方面。从长远来看，加强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的预测能力。主要目标是确定极光分裂与全球磁层电流系统之间的关系。该方法包括相对于现行系统的极光破裂时间和位置的个案研究和统计关联。这项研究现在才有可能，因为NSF-NASA安培计划突破性地利用66颗商业Ir星通信卫星上的现有工程磁力计，以10分钟的节奏绘制了全球场向电流地图。这些地图将与NSF-NASA-ESA支持的SuperMAG计划的地磁场扰动地面地图结合在一起，该计划是各组织和国家机构的全球合作，目前运营着300多台地面磁强计。SuperMAG将这些观测转化为磁场扰动的全球地图和其他衡量地磁活动水平的参数。最后，极光分解图像将从分布在整个北美极地地区(一些由美国国家科学基金会资助的一些站点)的20台THEMIS地面全天成像仪(ASIS)获得。

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).