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

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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.