Abstract
The Yunyao Aerospace Constellation Program is the core project being developed by Yunyao Aerospace Technology Co., Ltd. It aims to provide scientific data for weather forecasting, as well as research on the ionosphere and neutral atmosphere. It is expected to launch 90 high time-resolution weather satellites. Currently, the Yunyao space constellation provides nearly 16,000 BDS, GPS, GLONASS and Galileo multi-system occultation profile products on a daily basis. This study independently calculates the precise orbit of LEO satellites using a separate system and inverses the neutral atmospheric refractive index profile product. The precision of the orbit product was evaluated by comparing carrier phase residuals and overlapping orbits. Simultaneously, the global distribution, local time distribution, and detection depth of the constellation were statistically analyzed. BDS has the highest number of contours and the best detection capability among the three GNSS systems.The refractive index profile product was also compared with the ECWMF ERA5 product from ECWMF. Near the top of the occultation, the standard deviation in the refractive index is higher for BDS than GPS and GLONASS. BDS also outperforms GPS and GLONASS in terms of the standard deviation in the atmospheric refractive index. These results indicate that Yunyao satellites can provide high-quality occultation product services for applications such as weather forecasting. With the successful establishment of the global BDS-3 network, the accuracy of space signals has been further improved, making the full-link occultation products of BDS superior to those of GPS and GLONASS.