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。将制定全球定位系统数据集的常规分析程序。该方法将得到验证，并与目前的电离层和等离子体层模型以及其他独立的测量数据进行比较。配备了双频GPS接收器(FedSat、CHAMP、GRACE、SAC-C等)和地面双频GPS接收器的低地球轨道(LEO)卫星为遥感和监测电离层顶部和等离子体层提供了极好的机会。将使用层析重建方法对电离层和等离子体层密度的详细结构进行成像。这些组合观测的优点包括：将低轨全球定位系统数据与地面全球定位系统结合起来，可以明确测量等离子体层和电离层对总电子含量的相对贡献。由于有相当多的低轨卫星以不同的轨道倾角运行，因此可以绘制电离层和等离子体层顶部的全球地图。这与纯地面GPS TEC测量形成鲜明对比，后者仅限于有限的陆地地理区域。将产生两种不同的层析重建，地面重建和空间重建。这将使我们有可能获得磁层内部的电子密度分布，理解被认为是等离子体层密度损失和再填充的主要原因的场线等离子体传输，并推断风暴时间对流电场在M-I耦合动力学中的作用。该项目还将把断层重建的结果与利用极光辐射图像确定的等离子体停滞图像进行比较。综合观测将确定中纬度地区(通常称为中纬度槽)的电离层密度损耗与等离子体顶层之间的关系。在未来，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体层。随着对不断增加的低轨卫星星座(例如COSMIC)和即将到来的伽利略卫星星座用于地面和天基TEC观测的数据进行审查，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气象业务系统将是重要的。

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.