Assessing the feasibility of atmospheric water vapor monitoring with standalone BDS receiver.

The accurate monitoring of atmospheric water vapor is important for disaster prevention and environmental management. The ground-based BeiDou Navigation Satellite System (BDS) technique for atmospheric water vapor monitoring has demonstrated high accuracy and stable performance. Considering autonomy and safety, the standalone BDS receiver will be promoted in China and its surrounding areas for meteorological applications. To verify the feasibility of standalone BDS receivers for atmospheric water vapor monitoring, we evaluated the accuracy        of precipitable water vapor (PWV) retrieved from standalone BDS receivers and compared it with common multi-GNSS receivers using radiosonde and ERA5 products as references. The results showed that the zenith tropospheric delay (ZTD) derived from standalone BDS receivers achieved a root mean square (RMS) of 8.2 mm compared with the International GNSS Service (IGS) final zenith path delay (ZPD) products from co-located IGS Multi-GNSS Experiment (MGEX) stations. Subsequently, the PWV values derived from the two types of receivers were assessed with the radiosonde and ERA5-derived PWV. Compared with radiosonde, the RMS of the PWV differences for standalone BDS and IGS MGEX receivers was 1.9 and 1.6 mm, respectively. While compared with the ERA5 products, the RMS was 1.5/1.7 mm for IGS MGEX stations and 1.7/1.9 mm for standalone BDS stations. The monitoring performances during rainy and non-rainy days were further analyzed, and negligible differences (less than 0.15 mm) between the PWV accuracies were observed. This partially demonstrates that compared with the IGS MGEX receivers, the standalone BDS receiver is capable of monitoring atmospheric water vapor with consistent accuracy under all-weather conditions.