Global Navigation Satellite System (GNSS) radio occultation (RO) data are an important component of numerical weather prediction (NWP) systems. To incorporate more GNSS-RO data into NWP systems, commercial RO data have become an excellent option. Tianjin Yunyao Aerospace Technology Co., Ltd. (YUNYAO) plans to launch a meteorological constellation of 90 satellites equipped with GNSS-RO instruments, which will significantly increase the amount of GNSS-RO data in NWP systems. This study evaluates the quality of neutral atmospheric refractivity and bending angle profiles from YUNYAO satellites Y003 to Y010 during the period from 1 May to 31 July 2023. Compared with the refractivity and bending angle calculated from ERA5, the absolute values of the mean bias (MB) for YUNYAO refractivity and bending angle data are less than 1.54 % and 4.51 %, respectively, in the height range of 0 to 40 km and close to 0 between 4 and 40 km. The standard deviations (SDs) are below 3.35 % and 11.06 %, respectively, with variations in SDs among different GNSS satellites, especially in the lower troposphere and the stratosphere. Second, the refractivity error SD of YUNYAO RO data is estimated using the “three-cornered hat” (3CH) method and multiple data sets. In the pressure range of 1000–10 hPa, the refractivity error SD of YUNYAO RO data is below 2.53 %, and the differences in refractivity error SDs among different GNSS satellites do not exceed 0.52 %. Finally, compared to COSMIC-2 and Metop-C RO data, YUNYAO RO data exhibit consistent refractivity error SDs and are smaller within 300–50 hPa.

A record-breaking extreme rainstorm occurred in Henan Province of China on 20 July 2021. To investigate the impacts of the Geostationary Interferometric Infrared Sounder (GIIRS) data assimilation on model analysis and forecasts of this rainfall event, the high temporal resolution GIIRS water vapor (WV) channel data were assimilated in the high-resolution CMA-MESO (Mesoscale Weather Numerical Forecast System of China Meteorological Administration) in this study. The results showed that the GIIRS WV radiance assimilation could improve the model WV analysis, which in turn adjusted the distributions of hydrometeors (radar composite reflectivities) and wind field, and finally improved the precipitation forecast. Additionally, although barely any GIIRS observations were assimilated over the cloudy area, the precipitation forecast errors of “21·7” extreme rainstorm events could be reduced by improving the structure of atmospheric circulations through the assimilation of neighboring data around Henan, especially over the upstream region. With the GIIRS WV data assimilation, the location error of maximum 24-h accumulated precipitation forecasts decreased from 128.48 km to 28.97 km (improved by 77.45%) for the cold start at 0000 UTC (Universal Time Coordinated) on 19 July 2021, and it was also reduced by about 60.52% for the warm start experiment at 0600 UTC on 19 July 2021. In addition, the GIIRS assimilation experiment showed an extraordinarily heavy rainfall area (above 250 mm/24 h) around Zhengzhou station, which did not appear in the control experiment, and was closer to the observed extreme precipitation. This study demonstrates the potential value of geostationary hyperspectral infrared sounders data assimilation in extreme weather early warning and forecasting.

Balloon-borne radiosonde observations constitute a crucial component of meteorological sounding, which conducts a ground to upper-air “ascent phase” sounding. This paper introduces the Ascent-Drift-Descent Radiosonde System (ADDRS), an innovative system characterized by three observation phases – “Ascent-Drift-Descent” (ADD) – in which all three phases of sounding observation are executed through single balloon launch. Several key technologies were successfully developed, including the carrier (dual-mode balloon), the payload (System-on-Chip (SoC) module for radiosonde), Ground to upper-air data reception and control command transmission and data processing framework based on “Internet cloud + Instrument terminal” was established. Data quality control methods and data assimilation techniques of ADDRS were also developed. An interactive experiment encompassing observations and forecasting was conducted to evaluate the quality of experimental data at each phase of ADDRS. Numerical assimilation and forecasting experiments showed a positive (albeit not yet statistically significant) impact on forecast quality for both general cases and for Tropical cyclone cases. The pre-operational launching and assimilation of more than 100 such radiosondes started on 1 July 2024 and provided data over 1 year, and the number of stations continues to grow.