GEM: High Latitude M-I Coupling Studies Using Data Assimilation

该项目的主要科学目标是提高我们对地球电离层和磁层之间电磁耦合的认识。高纬度对流电场、场向电流（FAC）和电导的分布将使用一套独特的工具以提高空间和时间分辨率来确定。所得分布将用于研究以下M-I耦合科学问题：1)FACs的基本特征是什么？2)在风暴和亚风暴期间FAC模式是如何发展和增长的？3)饱和事件时电位与FACs的关系是什么？4) FAC告诉我们关于离子和电子等离子体片的变异性是什么？5)磁层能量输入的分布是怎样的？对电离层-热层系统有什么影响？新的高纬度电动力学描述工具将结合I/T系统的第一性原理模型（热层-电离层-中间层-电动力学环流模型（TIMEGCM））、基于数据的电离层电子密度客观分析模型（电离层数据同化三维模型（IDA3D））和电离层电动力学同化映射（AMIE）算法。TIMEGCM和IDA3D将结合起来提供将被AMIE吸收的全球电导估计值。AMIE吸收了各种其他电动力学数据集，以获得高纬度电位模式、电导和场向电流的全球地图。AMIE输出场（对流和粒子）将反过来用于驱动TIMEGCM，预测对M-I耦合规范的全局响应。目前，AMIE、TIMEGCM、IDA3D和卫星远紫外线（FUV）成像仪（如GUVI和IMAGE）获得的电导值存在分歧。在AMIE场驱动下，TIMEGCM电导与AMIE电导基本一致。电导将通过与Sondrestrom非相干散射雷达数据的比较来验证。对于给定的粒子特性，我们将比较TIMEGCM的电离率与GLOW极光代码的电离率。该提案汇集了一群广泛的磁层，I-T和电动力学专家来解决提出的科学问题。这项工作代表了对磁层-电离层耦合研究的重要贡献，这是一个关键的研究领域，因为我们试图了解控制日地关系和空间天气的过程链。最后，这项研究也可能建议改进目前正在开发的各种全球地球空间模型，如CISM（综合空间天气建模中心），它代表了社区对日地耦合的理解的精粹。拟议的研究将促进发现和理解，同时也促进教学、培训和学习。这里提出的研究的很大一部分将由德克萨斯大学圣安东尼奥分校的一名女研究生进行。UTSA是一个少数民族服务机构。加州大学伯克利分校的一名学生也将获得该项目的部分资助。拟议的活动还将有利于社会，有助于了解影响卫星寿命和轨道的地球空间环境的变化，以及诸如导航、通信和监视系统等技术系统。

The main science goal of this project is to improve our understanding of the electromagnetic coupling between Earth's ionosphere and magnetosphere. The distributions of the high latitude convection electric fields, field aligned currents (FAC) and conductances will be determined with improved spatial and temporal resolution using a unique set of tools. The resulting distributions will be used to investigate the following M-I coupling science questions: 1) What are the basic characteristics of the FACs? 2) How does the FAC pattern develop and grow during storms and substorms? 3) What is the relationship between electric potential and FACs during saturation events? 4) What do FAC tell us about variability in the ion and electron plasma sheets? 5) What is the distribution of magnetospheric energy input, and what are consequences for the Ionosphere-Thermosphere system? The new tool to describe high latitude electrodynamics will be developed by combining a first-principles model of the I/T system (the Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIMEGCM)) with a data-based objective analysis model of ionospheric electron density (Ionospheric Data Assimilation Three Dimensional (IDA3D)), and the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) algorithm. TIMEGCM and IDA3D will be combined to provide global conductance estimates that will be assimilated by AMIE. AMIE assimilates various other electrodynamic datasets to obtain global maps of the high latitude potential pattern, conductance, and field aligned currents. AMIE output fields (convection and particles) will in turn be used to drive the TIMEGCM, predicting global responses to the M-I coupling specification. There is currently a disagreement between the values of conductances obtained from AMIE, TIMEGCM, IDA3D, and satellite Far Ultra-violet (FUV) imagers such as GUVI and IMAGE. The TIMEGCM conductance generally agrees well with AMIE when it is driven by AMIE fields. The conductances will be validated by comparison with data from the Sondrestrom Incoherent Scatter radar. We will compare the TIMEGCM ionization rates with those from the GLOW auroral code for given particle characteristics. The proposal brings together a broad group of magnetosphere, I-T, and electrodynamics experts to address the proposed science questions. This work represents an important contribution to the study of magnetosphere-ionosphere coupling, which is a key area of study as we seek to understand the chain of processes that govern solar-terrestrial relations and space weather. Finally, this study may also suggest improvements in the various global geospace models currently under development such as CISM (Center for Integrated Space-weather Modeling), which represent the distillation of the community's understanding of solar-terrestrial coupling. The proposed study will advance discovery and understanding while also promoting teaching, training and learning. A significant portion of the research proposed here will be performed by a female graduate student at the University of Texas at San Antonio. UTSA is a minority serving institution. A student at UC Berkeley will also be partially funded by this project. The proposed activity will also benefit society in helping to understand variability in the geospace environment, which affects satellite lifetimes and orbits, and technological systems such as navigation, communications and surveillance systems.