High-Resolution Empirical Reconstruction of the Geomagnetic Field as a Space Weather Research Tool

基于数据的地磁场建模和预报是空间气象研究的一个关键要素。地球主磁场的风暴和亚风暴扰动是空间天气扰动的主要指标之一，它们还有助于评估其他影响，如粒子降水和等离子体加热。地球磁层数据量的急剧增加使新一代具有更多自由度和复杂数据仓储技术的经验地磁场模型成为可能。有一套相应的数据入库、数据拟合和可视化程序，称为TS07D模型，现已在磁层应用中广泛使用。在项目中，TS07D模型将在三个关键方面进行改进。首先，将对数据入库过程进行优化，以在系统级参数的数量(如太阳能风电场)及其预测精度之间实现平衡。作为这项任务的一部分，数据入库方法将作为一种模式识别工具进行测试，它有助于揭示新类别的磁暴，例如包括锯齿事件在内的风暴。其次，对假设各向同性等离子体静态力平衡所得到的有效热等离子体压力形式的模型输出进行了研究。推导出的压强可用于全球MHD模型，以改进等离子体状态方程，并描述环电流的建立和衰减。它还可用于改进动力学环电流模型中的外部边界条件，以及与从内磁层高能中性原子成像中提取的全球等离子体图样进行直接比较。第三，将研究对模型的场对齐电流部分进行修改，以将其转换为一组灵活的电流模块，其脚点分布与低空观测一致。该模型还将被重写为单语言代码，假定计算机集群上的不同平台和多线程操作。这项研究的结果将是一个改进的磁层磁场模型。虽然对上述模型的直接研究将是有价值的，但该模型将具有更大的价值。磁层磁场模型被其他研究人员广泛应用于磁层物理的其他领域。由于发生在磁层和电离层不同部分的现象是由磁场耦合的，该模型可以用来绘制这两个区域之间的现象图。该模型可用于确定带电粒子的运动轨迹。最后，它们可以用来向研究人员提供他们没有观测到的区域的磁场估计。

Data-based modeling and forecasting of the geomagnetic field is a key element of space weather research. Storm and substorm perturbations of the Earth's main magnetic field are among the main indicators of space weather disturbances, and they also help assess other effects such as particle precipitation and plasma heating. A dramatic increase in the amount of data for the terrestrial magnetosphere has made possible a new generation of empirical geomagnetic field models with much larger numbers of degrees of freedom and sophisticated data-binning techniques. A set of the corresponding data-binning, data-fitting and visualization procedures known as the TS07D model is available and widely used in magnetospheric applications. In the project the TS07D model will be improved in three critical aspects. First, the data-binning process will be optimized to achieve a balance between the number of system-level parameters, such as the solar wind electric field, and their forecasting accuracy. As a part of this task the data-binning method will be tested as a pattern-recognition tool, which helps reveal new classes of magnetic storms such as the storms that include saw tooth events. Second, the model output in the form of the effective hot plasma pressure inferred by assuming static force balance for an isotropic plasma will be investigated. The inferred pressure can be used in global MHD models to improve the plasma equation of state and to describe the ring current buildup and decay. It can also be used for the improvement of external boundary conditions in kinetic ring current models, as well as for direct comparison with global plasma patterns retrieved from the energetic neutral atom imaging of the inner magnetosphere. Third, a modification of the field-aligned current part of the model will be studied to transform it into a flexible set of current modules whose foot-point distributions are consistent with low-altitude observations. The model will also be rewritten as a single-language code assuming different platforms and multi-thread operations on computer clusters. The results of this investigation will be an improved magnetospheric magnetic field model. While direct research with the model described above will be valuable, the model will have an even greater value. Magnetospheric magnetic field models are widely used in other applications in magnetospheric physics by other researchers. Since phenomena occurring in different parts of the magnetosphere and the ionosphere are coupled by the magnetic field the model can be used to map phenomena between these two regions. The models can be used to determine the trajectories of charged particles. Finally they can be used to give an investigator an estimate of the magnetic fields in regions where they do not have observations.