GEM: Assessing the Relative Importance of Convection and Induced Electric Fields for Particle Transport and Energization in the Inner Magnetosphere

GEM：评估对流场和感应电场对于内磁层中粒子传输和能量化的相对重要性

• 批准号: 1602862
• 负责人: Margaret Chen
• 金额: $ 34.2万
• 依托单位: Aerospace Corporation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-15 至 2022-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1602862&HistoricalAwards=false
• 关键词: GEM; Assessing; Relative; Importance; Convection

This project investigates the importance of convection and induction electric fields in the magnetosphere, and their relative roles in the dynamics of the ring current and the plasmasphere. Convection electric fields are generated by the interaction between the solar wind and the Earth's magnetosphere. They are directed approximately from dawn to dusk across the magnetotail and drive plasma sheet ions and electrons from the magnetotail towards the inner magnetosphere. Along the way, convection electric fields play an important role in energizing these plasma sheet particles to high energies and in delivering them to build the storm-time ring current, a torus of high-energy ions and electrons surrounding the Earth. Convection electric fields also play an important role in the location of plasma boundaries, such as the plasmapause. The plasmapause is the steep outer boundary of the plasmasphere, a dense torus formed by the extension of cold ionospheric plasma into the inner magnetosphere. This torus expands outward to occupy the region where the corotation electric field (a radial electric field produced by the movement of magnetic field lines in response to Earth's rotation) dominates over the convection electric field. In disturbed times, the convection electric field strengthens with respect to the essentially unchanging corotation field, diminishing the region where the corotation field dominates. As a result, the outer regions of the plasmasphere are stripped away and convected to the dayside magnetopause where the plasma is lost. However, the electric field is more complicated than the superposition of these two large-scale electric fields. Changing magnetic fields produce electric fields through induction. During magnetic substorms, explosive reconfigurations of the magnetotail fields produce significant "induction" electric fields that introduce smaller scale temporal and spatial variability into the magnetospheric electric field. The primary goal of this proposal is to quantify the relative contributions to inner magnetosphere dynamics of convection and induction electric fields. A more complete understanding of all components of the magnetospheric electric field is important for developing improved space weather forecast models of value to society. This project provides support for the research career of a productive female scientist, and a research experience for an undergraduate intern as well as yearly outreach activities aimed at K-12 students, thus contributing to the future scientific workforce and science literacy. The primary tool for this investigation is a magnetically and electrically self-consistent model of the inner magnetosphere, the Rice Convection Model-Equilibrium (RCM-E). For storm events, measurements of the electric fields in the inner magnetosphere and ionosphere will be compared with the modeled RCM-E electric fields. Initially storms will be simulated with no explicit substorm magnetic field changes. The RCM-E magnetic field, energetic ion fluxes, electron densities, and precipitating electron fluxes will be compared with in-situ measurements by magnetospheric and ionospheric satellites. Finally, results of RCM-E geomagnetic storm simulations that incorporate the effects of substorm reconfigurations of the magnetotail fields will be compared with data to determine the role and importance of induced electric fields.

本计画探讨磁层中对流与感应电场的重要性，以及它们在环电流与电浆磁层动力学中的相对角色。对流电场是由太阳风和地球磁层之间的相互作用产生的。 它们大约从黎明到黄昏穿过磁尾，并将等离子体片离子和电子从磁尾推向内磁层。 沿着，对流电场在将这些等离子体片粒子激发到高能量并将其输送到建立风暴时间环电流（围绕地球的高能离子和电子的环面）方面发挥着重要作用。 对流电场在等离子体边界的位置上也起着重要的作用，例如等离子体层顶。 等离子体层顶是等离子体层顶的陡峭外边界，是由冷电离层等离子体延伸到内磁层而形成的致密环面。 这个环面向外扩展，占据了共转电场（响应地球自转的磁场线运动产生的径向电场）主导对流电场的区域。 在扰动时间，对流电场加强相对于基本不变的共转场，减少共转场占主导地位的区域。 结果，等离子体层的外部区域被剥离并对流到向阳面的磁层顶，在那里等离子体消失。 然而，电场比这两个大规模电场的叠加更复杂。 变化的磁场通过感应产生电场。在磁亚暴期间，磁尾场的爆炸性重新配置产生显著的“感应”电场，其将较小尺度的时间和空间变化引入磁层电场。这个建议的主要目标是量化对流和感应电场的相对贡献内磁层动力学。 更全面地了解磁层电场的所有组成部分对于开发对社会有价值的改进空间气象预报模型十分重要。 该项目为一名富有成效的女科学家的研究生涯提供支持，为一名本科实习生提供研究经验，并为K-12学生提供年度外联活动，从而为未来的科学劳动力和科学素养做出贡献。 本研究的主要工具是磁层内部的磁和电自洽模型，赖斯对流模型-平衡（RCM-E）。对于风暴事件，内磁层和电离层电场的测量值将与模拟的RCM-E电场进行比较。最初的风暴将模拟没有明确的亚暴磁场变化。RCM-E磁场、高能离子通量、电子密度和沉淀电子通量将与磁层和电离层卫星的现场测量结果进行比较。最后，RCM-E磁暴模拟的结果，包括亚暴的磁尾场重新配置的影响将与数据进行比较，以确定感应电场的作用和重要性。