LAUSR

Aiming at weather forecast and global climate research, the satellite FengYun-3C (FY-3C), as the new generation of China’s weather satellites, was launched in 2013. It carries the Global Navigation Satellite Systems Occultation Sounder instrument, a BDS + GPS receiver, to fulfill the demand of orbit determination and occultation. In this contribution, we develop an integrated orbit determination of FY-3C, BDS, and GPS satellites by joint processing of onboard FY-3C and ground data during 2013–2017. Four processing schemes, BDS, GPS, BDS + GPS, and BDS (without Geostationary Earth Orbit [GEO]) + GPS, are designed to investigate the capability of BDS for the integrated precise orbit determination and the benefit of BDS and GPS fusion. Regional and global networks are also employed to analyze the influence of station distribution on the orbit determination. The results show that with a regional network, both BDS and GPS orbits present a significant improvement after including FY-3C data. For the BDS + GPS one-step solution, GPS orbits are improved by 20% compared with the two-step solution, while the improvement can reach 42%, 27%, and 27% for BDS GEO, Inclined Geosynchronous Satellite Orbit, and Medium Earth Orbit, respectively. The precision improvement of FY-3C is respectively 26%, 44%, and 30% in along, cross, and radial components. For a global network, the orbit precision of the BDS + GPS solution is improved by 4% for GPS and 5%, 16%, and 19% for BDS GEO, Inclined Geosynchronous Satellite Orbit, and Medium Earth Orbit, respectively. For FY-3C, the orbit improvement can reach 7%. The validation with satellite laser ranging also demonstrates the benefit of the integrated orbit determination. Such a high-quality orbit will potentially benefit meteorological studies and applications.