Ionospheric-plasmaspheric variations and mechanism from multi-satellite space-based GNSS measurements

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The ionosphere and plasmasphere cover the altitude of about 60 km height up to the plasmapause at about 3-5 Earth radii in the equatorial plane, whose variations are very complex and strongly coupled. The investigation of ionosphere-plasmasphere coupling processes contributes essentially to understand the observed ionospheric and plasmaspheric variations under regular and perturbed conditions. Recently, a number of GNSS radio occultation missions, e.g., CHAMP, COSMIC and Fengyun-3C, provide a unique opportunity to retrieve the ionospheric and plasmaspheric total electron content (TEC) and electron density for studies of ionospheric-plasmaspheric variations and space weather with high spatial resolution. In order to fully utilize the potential of these missions we suggest the implementation of new approaches, among them a new mapping function for geometrical transformation of observation data, receiver bias and phase center variation (PCV) estimates of Low Earth Orbit (LEO) satellites. Multi-satellite GNSS observations as well as higher order ionospheric propagation effects on ionospheric and plasmaspheric parameters estimates are considered and reduced. Improved TEC estimates of the topside ionosphere-plasmasphere electron content and vertical electron density profiles will be used to study climatological features of the ionosphere and ionosphere-plasmasphere relationships, identify and study some specific electron density profile shapes like the E-layer dominated ionosphere (ELDI) at high latitudes. Furthermore, ionospheric anomalies as the Weddell sea and Okhotsk sea anomaly or the Mid Summer Nighttime Anomaly (MSNA) and the Nighttime Winter Anomaly (NWA) are studied that might be explained by strong ionosphere-plasmasphere coupling. Thus, besides considering the thermospheric composition ratio of dominating neutrals like [O]/[N2], the investigations include vertical plasma drifts and related dynamic forces such as neutral winds and electric fields.The proposed joint project between DLR and SHAO can essentially contribute to the International space weather Meridian Circle Program (IMCP) and provides an excellent basis for new scientific findings in ionosphere-plasmasphere physics.