GEM-CEDAR Postdoc: Understanding MIC through Tomographic Imaging of the Ionospheric and Plasmaspheric Density Using Ground and Space-Based GPS Receiver

该项目将结合使用地面和天基全球定位系统（GPS）接收器的技术，研究内磁层等离子体的全球密度结构。将制定常规分析GPS数据集的程序。该方法将与当前电离层和等离子体层模型以及其他独立测量数据进行验证和比较。配备双频GPS接收机（FedSat、CHAMP、GRACE、SAC-C等）和地面双频GPS接收机的低地球轨道卫星为上层电离层和等离子层的遥感和监测提供了极好的机会。层析重建方法将用于成像电离层和等离子体层密度的详细结构。这些联合观测的优点包括：将LEO-GPS数据与地面GPS数据相结合，可以明确测量等离子层和电离层对总电子含量（TEC）的相对贡献。由于有相当多的低轨道卫星在不同的轨道倾角上运行，因此可以制作上层电离层和等离子层的全球地图。这与仅限于有限陆地地理区域的纯地面GPS TEC测量形成鲜明对比。将生成两个独立的层析重建，地面和空间。这将有可能获得内磁层的电子密度分布，了解被认为是等离子层密度损失和再填充的主要原因的场线等离子体输运，并推断风暴时间对流电场在M-I耦合动力学中的作用。该项目还将把层析重建的结果与使用IMAGE EUV图像确定的等离子体顶图像进行比较。这些综合观测将确定中纬度地区（通常称为中纬度槽）电离层密度耗竭与等离子体顶之间的关系。未来，将开发的分析工具将能够近乎实时地监测电离层和等离子层。随着不断增加的低轨道卫星星座（例如COSMIC）和即将用于地面和天基TEC观测的伽利略卫星星座的数据得到审查，这项技术的空间分辨率将继续提高。这种实时监测对未来的空间天气操作系统非常重要。

This project will examine the global density structure of the plasma in the inner magnetosphere using a combination of techniques that use ground- and space-based Global Positioning System (GPS) receivers. Procedures will be developed for the routine analysis of GPS datasets. The method will be validated and compared with current ionospheric and plasmaspheric models and other independent measurement data. The Low-Earth-Orbit (LEO) satellites equipped with dual-band GPS receivers (FedSat, CHAMP, GRACE, SAC-C, and many more) and ground-based dual-band GPS receivers offer an excellent opportunity for remote sensing and monitoring of the topside ionosphere and plasmasphere. A tomographic reconstruction approach will be used to image the detailed structure of ionospheric and plasmaspheric density. The advantages of these combined observations include: Combining the LEO-GPS data with ground-based GPS allows the explicit measurement of relative contributions of the plasmasphere and ionosphere contribution to the total electron content (TEC). Because there are quite a number of LEO satellites orbiting at different orbital inclinations, a global map of the topside ionosphere and plasmasphere can be made. This is in sharp contrast with purely ground-based GPS TEC measurements that are confined to limited land-based geographic regions. Two separate tomographic reconstructions, ground-based and space-based will be generated. This will make it possible to obtain electron density profiles of the inner magnetosphere, understand the field-line plasma transport which is thought to be the principal agent for the density loss and refilling of the plasmasphere, and infer the role of storm time convection electric fields in the dynamics of M-I coupling. The project will also compare the results of the tomographic reconstructions with images of the plasmapause determined using the IMAGE EUV images. The combined observations will identify the correlation between the ionospheric density depletion in the mid-latitude region (usually called the mid-latitude trough) and the plasmapause. In the future, the analysis tools that will be developed will be able to monitor the ionosphere and plasmasphere in near real time. The spatial resolution of this technique will continue to improve as data from the ever-increasing LEO satellite constellations (e.g., COSMIC) and the upcoming GALILEO satellite constellation for ground- and space-based TEC observation are examined. Such real-time monitoring will be important for future space weather operational systems.