## 5 Conclusions
In contrast, the upper altitude difference is attributed to the excess phase algorithm regarding the clock bias removal, the ionospheric correction, and the positional errors, which are small but can be amplified due to the small bending angle comparison as the relative bending angle difference. The produced datasets, including the excess phase and bending angle profiles, are available through the NOAA STAR Radio Occultation team ICVS Website (ICVS). In this study, we have developed our radio occultation package to examine various error terms and their sources to understand better the RO inversion algorithm and RO data quality control. As a part of a future mission to improve the RO data quality, we will keep working on Bernese GNSS software for POD and dynamic orbital solution and validation, using ground observation for GNSS clock removal, further improvement in the receiver clock removal algorithm, resolving issues near the surface (open-loop phase model) using ROPP or STAR FSI algorithm with further improving the ROPP processing. We will also work on automating the RO processing and expanding the work to other RO missions, including GeoOptics, SPIRES, COSMIC-1, and KOMPSAT\(-5\). **Author Contributions:** Conceptualization, B.Z. and C.C. ; methodology, B.Z. ; software, B.Z. and J.D. ; validation, B.Z. and J.D. ; formal analysis, B.Z. ; investigation, B.Z. ; resources, X.S. and S.-p.H. ; data curation, B.Z. and J.D. ; writing--original draft preparation, B.Z. ; writing--review and editing, B.Z., S.-p.H., X.S., C.C., Y.C. and J.D. ; visualization, B.Z. and J.D. ; supervision, S.-p.H. ; project administration, X.S. ; funding acquisition, S.-p.H. All authors have read and agreed to the published version of the manuscript. **Funding:** This research was funded by NOAA grant NA19 NES4320002 (Cooperative Institute for Satellite Earth System Studies--CISESS) at the University of Maryland/ESIC. **Data Availability Statement:** NOAA STAR RO ICVS ([[https://www.star.nesdis.noaa.gov/data/smcd1/icvs_GNSSRO/GNSSRO_COSMIC2/index.html](https://www.star.nesdis.noaa.gov/data/smcd1/icvs_GNSSRO/GNSSRO_COSMIC2/index.html)]([https://www.star.nesdis.noaa.gov/data/smcd1/icvs_GNSSRO/GNSSRO_COSMIC2/index.html](https://www.star.nesdis.noaa.gov/data/smcd1/icvs_GNSSRO/GNSSRO_COSMIC2/index.html)), accessed on 6 June 2022). **Acknowledgments:** We thank the three anonymous reviewers for their constructive suggestions and comments. We also thank NOAA STAR RO team for their help on this research. We would like to thank our EUMETSAT RO team for their dedicated training provided to us on RO technique and knowledge, as well as later useful discussion on various aspects. We also thank UCAR CDAAC for providing the COSMIC-2 satellite antenna information for POD and Excess Phase calculation. We also thank the Bernese software team at Astronomical Institute, University of Bern, for providing us with a one-week Bernese software workshop. The scientific results and conclusions, as well as any views or opinions expressed herein, are those of the author(s) and do not necessarily reflect those of NOAA or the Department of Commerce. **Conflicts of Interest:** The authors declare no conflict of interest.