Review of recent GNSS modelling improvements based on CODEs Repro3 contribution. Issue 3 (1st August 2021)

• Record Type: Journal Article
• Authors: Dach, Rolf; Selmke, Inga; Villiger, Arturo; Arnold, Daniel; Prange, Lars; Schaer, Stefan; Sidorov, Dmitry; Stebler, Pascal; Jäggi, Adrian; Hugentobler, Urs
• Is Part Of: Advances in space research. Volume 68:Issue 3(2021)
• Page Start: 1263
• Page End: 1280
• Publication Date: 2021-08-01
• Subjects: CODE reprocessing -- GNSS reprocessing -- GNSS orbit modeling -- Weighting of historic GPS data; Space sciences -- Periodicals; Astronautics -- Periodicals; Geophysics -- Periodicals; 500.505
• DOI: 10.1016/j.asr.2021.04.046
• Languages: English
• ISSNs: 0273-1177

Abstract

Abstract: The Center for Orbit Determination in Europe (CODE) is contributing to the most recent reprocessing effort of the International GNSS Service (IGS) with a triple-system solution including GPS (since 1994), GLONASS (since 2002) and Galileo (since 2013). Several model improvements with respect to the operational processing scheme have been implemented and applied for the reprocessing effort: The first group of improvements is related to the update of IERS-related models (mean pole and high-frequency pole models). The second group is related to the inclusion of Galileo with calibrated receiver and satellite antennas. The consistency of the scale for the ground station coordinates was verified based on the estimation of GNSS-specific coordinate biases. It turned out that currently widely used GPS-based receiver antenna calibrations do compensate (just by chance) a discrepancy in the scale when using the pre-launch satellite antenna calibrations for Galileo. Furthermore and third, a long-arc solution over three days is introduced where in particular empirical velocity changes are rescheduled with respect to the operational processing chain at CODE. Instead of simply estimating them every 12 h they are now setup at orbit midnight. This rescheduling reduces the size of orbit misclosures by 10% for GPS and 15% for Galileo; no improvement for GLONASS was observed because there the orbit misclosures are dominated by other effects. Another feature applied for the first time in this reprocessing series is to downweight the observations of a number of GPS satellites with a reduced stability in the attitude control around the year 2000. This change in the analysis strategy reduces the noise level of GNSS-derived products, e.g., of the Earth rotation series. Even if the article is focusing on the reprocessing series as provided by the CODE analysis center many of the conclusions may also be applied to other GNSS series in future.