Multi-GNSS orbit combination at Wuhan University: strategy and preliminary products

Multi-GNSS orbits from the analysis centres (ACs) of the multi-GNSS Pilot Project of the International GNSS Service (IGS) are combined at Wuhan University after aligning individual orbits to the IGS reference frame realized by the operational combined GPS orbits and assigning robust weights for each...

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Bibliographic Details
Published in:Journal of geodesy 2023-05, Vol.97 (5), Article 41
Main Authors: Chen, Guo, Guo, Jing, Geng, Tao, Zhao, Qile
Format: Article
Language:English
Subjects:
Earth and Environmental Science
Earth Sciences
Geodetics
Geophysics/Geodesy
Global positioning systems
GPS
Orbits
Original Article
Parameters
Pilot projects
Radiation pressure
Satellite observation
Satellites
Thermal radiation
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Summary:Multi-GNSS orbits from the analysis centres (ACs) of the multi-GNSS Pilot Project of the International GNSS Service (IGS) are combined at Wuhan University after aligning individual orbits to the IGS reference frame realized by the operational combined GPS orbits and assigning robust weights for each constellation. The consistency between combined orbit and individual AC solutions is assessed using the weighted root mean square of the orbit residuals over 2 years. In general, orbit comparison between the combined and AC solutions shows that the GPS orbits achieve the best consistency, followed by Galileo and GLONASS, BeiDou-2 and QZSS containing IGSO and GEO satellites, obtaining the largest scatter of orbit residuals. Moreover, the impacts of the change in processing strategies for individual ACs during precise orbit determination are also investigated in terms of constellation-specific transformation parameters. The obvious bias of scale and equatorial translation parameters derived from orbit comparison is identified, which may be related to the inclusion of more satellites and the updated phase centre offset (PCO). The updating of orbit models also shifts the orbit scale. The accuracy of the combined orbits is evaluated with satellite laser ranging (SLR) observations, and the root mean square of 2.3 cm, 3.6 cm, 5.0 cm and 2.9 cm is achieved for the Galileo, GLONASS, BeiDou-2 IGSO and BeiDou-2 MEO satellites during non-eclipse season, respectively, and it is at the decimetre level for the QZSS IGSO satellites. However, there are systematic sun elongation angle-dependent patterns in the SLR residuals for those satellites, which are mainly due to the noncubic shape of the satellites and partly generated by not modelling the thermal radiation pressure. Hence, refined orbit models are suggested to be adopted by ACs for multi-GNSS analysis.
ISSN:0949-7714
1432-1394
DOI:10.1007/s00190-023-01732-2