Ionospheric-plasmaspheric variations and mechanism from multi-satellite space-based GNSS measurements
The objective of the project is to use the available space-based GNSS measurements from CHAMP, GRACE, COSMIC, TerraSAR-X and Fengyun-3 to improve ionosphere models and to study ionospheric anomalies.
Space based GNSS measurements become more and more a significant data source for observing the ionosphere. Radio occultation and topside measurements can cover remote areas where ground-based GNSS reference networks are not available. Covering those areas is crucial for the understanding of ionospheric processes with their highly dynamic temporal and spatial changes. We will furthermore investigate and exploit the potential of space-based data for 3D modelling of the Ionosphere in near real-time.
The Earth’s 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. However, due to lack of in-situ measurements, it is difficult to quantify variations of the ionosphere and plasmasphere and understand their dynamics and interaction with the underlying ionosphere. Recently, a number of GNSS radio occultation missions, e.g., CHAMP, COSMIC, and China’s 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. The correction of higher order effects and accurate bias estimates will enable us to validate ionospheric models, particularly the 3D electron density model of the ionosphere–plasmasphere (Neustrelitz Electron Density Model – NEDM) that has been developed in DLR recently. 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.
06/2018 - 06/2021
Deutsche Forschungsgemeinschaft (GZ: HO 6136, AOBJ: 645519)
DFG Projektnummer 392206641
Shanghai Astronomical Observatory (SHAO)