Combination of space geodetic techniques
![[Translate to English:] Schematische Darstellung der Kombination geodätischer Weltraumverfahren](/fileadmin/_processed_/6/2/csm_kombination_e752bbfd0e.jpg)
The space geodetic techniques: Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS), Global Navigation Satellite Systems (GNSS), Satellite Laser Ranging (SLR), and Very Long Baseline Interferometry (VLBI) are combined to determine global terrestrial reference frames (TRFs). Each technique has its individual strengths and weaknesses and only a rigorous combination of the techniques enables the generation of highly accurate and stable global TRFs, which are one of the main products of geodesy. TRFs are the realization of global and regional terrestrial reference systems and can be understood as coordinate systems of the Earth. They provide the absolute reference for the relative geodetic measurements. Global TRFs are also indispensable for Earth system monitoring, e.g., to determine and predict the global sea-level rise. The TRF should be at least one order of magnitude more accurate than the observed effect. Therefore, the Global Geodetic Observing System (GGOS) has set specific requirements for global TRFs with an accuracy of 1 mm and stability of 1mm/decade. Currently available global TRFs do not meet these requirements. The importance of accurate and stable global TRFs is highlighted in the first United Nations (UN) resolution on geodesy adopted on February 26, 2015 (UN Resolution No. 69/266 “A Global Geodetic Reference Frame for Sustainable Development”, ggim.un.org/documents/A_RES_69_266_E.pdf).
Limitations in the TRFs are caused by remaining systematic effects in the space geodetic techniques as well as the combination thereof. We investigate different combination strategies such as classical (local ties and global ties), and innovative concepts like space ties and tropospheric ties. Furthermore, we examine technological and conceptional developments in space geodetic techniques. We utilize mainly simulations, but also real data analysis. We directly contribute to Topic 2 "Oceans and Cryosphere in Climate Change" (https://www.gfz-potsdam.de/en/research/topics/our-research-programme/our-research-programm-2021-2027) of the Helmholtz research program “Changing Earth – Sustaining our Future” (https://earthenvironment.helmholtz.de/changing-earth/program/).
Main research areas
Different combination strategies:
- Local ties, e.g., Glaser et al. (2019b)
Project: GGOS-SIM - Global ties, e.g., Glaser et al. (2015)
- Space ties, e.g., Mammadaliyev et al (2021), Schreiner et al. (2021)
Project: GGOS-SIM-2 - Tropospheric ties, e.g., Wang et al. (2022)
Developments in space geodetic techniques:
- Additional network stations, e.g., Glaser et al (2019a)
Project: GGOS-SIM - Next-generation GNSS, e.g., Giorgi et al. (2019), Glaser et al. (2020a)
Project: ADVANTAGE, NextGNSS4GGOS
Selected references
- Giorgi G, Schmidt T, Mata-Calvo R, Fuchs C, Hoque M, Berdermaan J, Furthner F, Günther C, Schuldt T, Sanjuan J, Gohlke M, Braxmaier C, Balidakis K, Dick G, Flechtner F, Ge M, Glaser S, König R, Michalak G, Murböck M, Semmling M, and Schuh H (2019) Advanced Technologies for Satellite Navigation and Geodesy. Advances in Space Research, doi:10.1016/j.asr.2019.06.010
- Glaser S, Fritsche M, Sośnica K, Rodríguez-Solano C J, Wang K, Dach R, Hugentobler U, Rothacher M, Dietrich R (2015) A consistent combination of GNSS and SLR with minimum constraints, Journal of Geodesy, DOI: 10.1007/s00190-015-0842-0
- Glaser S, König R, Neumayer K H, Balidakis K, Schuh H (2019a) Future SLR station networks in the framework of simulated multi-technique terrestrial reference frames, Journal of Geodesy, DOI: 10.1007/s00190-019-01256-8
- Glaser S, König R, Neumayer K H, Nilsson T, Heinkelmann R, Flechtner F, Schuh H (2019b) On the impact of local ties on the datum realization of global terrestrial reference frames, Journal of Geodesy, DOI: 10.1007/s00190-018-1189-0
- Glaser S, Michalak G, Männel B, König R, Neumayer K H, Schuh H (2020a) Reference system origin and scale realization within the future GNSS constellation “Kepler”, Journal of Geodesy, DOI: 10.1007/s00190-020-01441-0
- Glaser S, Schuh H, König R (2020b) Simulation globaler terrestrischer Referenzrahmen für das Globale Geodätische Beobachtungssystem GGOS (in German), zfv – Zeitschrift für Geodäsie, Geoinformation und Landmanagement, DOI: 10.12902/zfv-0308-2020
- Mammadaliyev N, Schreiner P, Glaser S, Neumayer K H, Koenig R, Heinkelmann R, and Schuh H (2021) Potential of VLBI observations to satellites for precise orbit determination, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12458, https://doi.org/10.5194/egusphere-egu21-12458
- Schreiner P, Mammadaliyev N, Glaser S, König R, Neumayer K H, Schuh H, (2021) On multi-technique simulation studies to single-satellite space-ties to achieve the Global Geodetic Observing System goals, AGU2021, https://agu.confex.com/agu/fm21/meetingapp.cgi/Paper/934508
- Wang J, Ge M, Glaser S, Balidakis K, Heinkelmann R, Schuh H (2022) Improving VLBI analysis by tropospheric ties in GNSS and VLBI integrated processing, Journal of Geodesy, 96, 32, DOI: 10.1007/s00190-022-01615-y
