Centimeter-Level Orbit Determination of GRACE-C Using IGS-RTS Data

GNSS real-time applications greatly benefit from the International GNSS Service's (IGS) real-time service (RTS). This service does more than provide for terrestrial precise point positioning (PPP); it also brings more possibilities for space-borne technology. With this service, the State-Space Representation (SSR) product, which includes orbit corrections and clock corrections, is finally available to users. In this paper, the GPS real-time orbit and clock corrections provided by 11 analysis centers (ACs) from the day of the year (DOY) 144 to 153 of 2022 are discussed from 3 perspectives: integrity, continuity, and accuracy. Moreover, actual observation data from the GRACE-C satellite are processed, along with SSR corrections from different ACs. The following can be concluded: (1) In terms of integrity and continuity, the products provided by CNE, ESA, and GMV perform better. (2) CNE, ESA, and WHU are the most accurate, with values of about 5 cm for the satellite orbit and 20 ps for the satellite clock. Additionally, the clock accuracy is related to the Block. Block IIR and Block IIR-M are slightly worse than Block IIF and Block IIIA. (3) The accuracy of post-processing reduced-dynamic precise orbit determination (POD) and kinematic POD are at the centimeter level in radius, and the reduced-dynamic POD is more accurate and robust than the kinematic POD.

Automated summary

GNSS real-time applications benefit greatly from the International GNSS Service's (IGS) real-time service (RTS). This paper discusses the GPS real-time orbit and clock corrections provided by 11 analysis centers (ACs) from days 144 to 153 of 2022, evaluating them from the perspectives of integrity, continuity, and accuracy. The study concludes that CNE, ESA, and GMV perform better in terms of integrity and continuity, while CNE, ESA, and WHU are the most accurate in terms of satellite orbit and clock corrections.