## 6 Conclusions
NOAA has operationally assimilated the RO observations from the current NOAA mission (i.e., COSMIC-2) and partners' missions (i.e., challenging minisatellite payload, Korea multi-purpose satellite-5 (KOMPSAT-5), meteorological operational satellite (MetOp) series -A/-B/-C global navigation satellite system receiver for atmospheric sounding (GRAS)) into the national centers for environmental prediction (NCEP) NWP systems. NOAA is also purchasing RO commercial weather data (CWD) from commercial vendors (i.e., GeoCptics,Inc., Pasadena, CA, USA, and Spire Global, Inc., Washington, DC, USA) and assimilating the CWD data into its NWP systems. All the global operational centers have assimilated the RO bending angle profiles in their NWP systems through data assimilation (DA). This study demonstrates that the STAR GNSS RO data processing and validation system is very useful for monitoring the measurements and retrievals and the observation uncertainty from the multiple RO missions, which are critically important for optimizing the usage of RO data in the numerical NWP system through data assimilation. Researchers [49; 50] have summarized the recent COSMIC-2 applications for meteorology and climate studies, which are not further detailed in this study. Conceptualization, S.-P.H. ; data curation, S.K. and X.Z. ; formal analysis, S.K. and S.-p.H. ; funding acquisition, S.-p.H. ; investigation, S.K., X.Z., X.S. and X.J. ; methodology, S.-p.H. and S.K. ; project administration, S.-p.H. ; resources, S.-p.H. and X.S. ; software, X.S. ; supervision, S.-p.H. and X.S. ; validation, S.K., X.Z., X.S. and X.J. ; visualization, S.K. and X.Z. ; writing--original draft, S.-p.H. and X.S. ; writing--review and editing, S.-p.H. and X.S. All authors have read and agreed to the published version of the manuscript. This study was supported by NOAA grant NA19 NES4320002 (Cooperative Institute for Satellite Earth System Studies--CISESS) at the University of Maryland/ESSIC. This work is also partially supported by the Technology Maturity Program of NOAA OPPA. At MMS data can be accessed at [[https://www.avl.class.noaa.gov/saa/products/search?sub_id=0&datatype_family=ATMS_SDR](https://www.avl.class.noaa.gov/saa/products/search?sub_id=0&datatype_family=ATMS_SDR)]([https://www.avl.class.noaa.gov/saa/products/search?sub_id=0&datatype_family=ATMS_SDR](https://www.avl.class.noaa.gov/saa/products/search?sub_id=0&datatype_family=ATMS_SDR)) (accessed on 26 September 2022). CrIS data can be accessed at [[https://www.avl.class.noaa.gov/saa/products/search?sub_id=0&datatype_family=CRIS_SDR](https://www.avl.class.noaa.gov/saa/products/search?sub_id=0&datatype_family=CRIS_SDR)]([https://www.avl.class.noaa.gov/saa/products/search?sub_id=0&datatype_family=CRIS_SDR](https://www.avl.class.noaa.gov/saa/products/search?sub_id=0&datatype_family=CRIS_SDR)) (accessed on 26 September 2022). STAR COSMIC-2 temperature and water vapor profile data can be downloaded from [[https://gpsmet.umd.edu/star_gnssro/data/cosmic2/wetPrf_STAR_ldvar/](https://gpsmet.umd.edu/star_gnssro/data/cosmic2/wetPrf_STAR_ldvar/)]([https://gpsmet.umd.edu/star_gnssro/data/cosmic2/wetPrf_STAR_ldvar/](https://gpsmet.umd.edu/star_gnssro/data/cosmic2/wetPrf_STAR_ldvar/)) (accessed on 26 September 2022). UCAR COSMIC-2 RO data can be downloaded from UCAR COSMIC Data Analysis and Archive Center (UCAR/CDAAC) at [[https://cdaac-www.cosmic.ucar.edu/cdaac/index.html](https://cdaac-www.cosmic.ucar.edu/cdaac/index.html)]([https://cdaac-www.cosmic.ucar.edu/cdaac/index.html](https://cdaac-www.cosmic.ucar.edu/cdaac/index.html)) (accessed on 26 September 2022). GFS data can be downloaded from the GFS website at [[https://www.ncdc.noaa.gov/data-access/model-data/model-datasets/global-forcast-system-gfs](https://www.ncdc.noaa.gov/data-access/model-data/model-datasets/global-forcast-system-gfs)]([https://www.ncdc.noaa.gov/data-access/model-data/model-datasets/global-forcast-system-gfs](https://www.ncdc.noaa.gov/data-access/model-data/model-datasets/global-forcast-system-gfs)) (accessed on 26 September 2022).