Integrated GNSS Processing for Earth System Monitoring

• Applicant: Dr. Benjamin Männel
• Subject Area: Geodesy, Photogrammetry, Remote Sensing, Geoinformatics, Cartography
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 446282290

Geodetic observations of Global Navigation Satellite Systems (GNSS) including today GPS, GLONASS, Galileo, and BeiDou have been used for more than 20 years to monitor the Earth system, to realize the International Terrestrial Reference System (ITRS) and to determine the orbital positions of Low Earth Orbiters in space. So far, space-based GNSS observations (tracked onboard LEOs) are not considered for the realization of the ITRS, despite their high quality, the absence of tropospheric delays, and the associate geometrical information provided by the LEO orbit dynamics. Space-based GNSS observations improve geodetic products by reducing correlations between parameters and by reducing systematic biases. The main objective of this project is to evaluate systematically the long-term impact of the combination of ground and space-based GNSS observations on station coordinates, satellite orbits, and the terrestrial reference frame. Compared to previous studies this proposal aims to incorporate space-based GNSS observations of as many low Earth orbits as possible (up to 20 spacecraft) for the longest possible time span (at least 20 years). This includes GNSS observations of missions dedicated to the gravity field (e.g., GRACE, GRACE-FO), altimetry (e.g., Jason-2, Jason-3), magnetic field (i.e., Swarm) but also the recently launched European Sentinel satellites and other missions. Consequently, the main output will be a long-term, fully consistent GNSS solution including station coordinates, reference frame parameters, GNSS and LEO satellite orbits, and Earth rotation parameters. The proposed project will provide major outcomes for improving the operational GNSS processing, for future satellite missions dedicated to co-location in space, and potential GNSS constellations including LEO segments.

• DFG Programme: Research Grants