COMPARISON OF GNSS PWV AND ERA5-DERIVED PWV BASED ON GNSS PWV IN HONG KONG, CHINA

Abstract. Water vapor is the most abundant atmospheric gas, and it plays a vital role in the evolution of the Earth's climate. Precipitable water vapor (PWV) is a key factor in monitoring the climate and hydrological cycle. The use of GNSS to estimate PWV is a very effective method. This paper uses 17 satellite positioning reference stations in SatRef, Hong Kong, China, in 2017 to calculate the PWV and introduce the latest reanalysis data set of the European Medium Range Weather Forecast Ingenued Center (ECMWF) ERA5 into this study. The accuracy of THE PWV derived from ERA5 was evaluated using the GNSS-derived PWV. In Hong Kong, the annual bias and RMSE values of GNSS-derived ZTD and ERA5-derived ZTDs are 1.16 cm and 1.78 cm respectively, while the annual RMSE values of GNSS-derived PWV and ERA5-derived PWV are 0.51 cm and 0.57 cm, respectively. The daily changes of GNSS PWV in 2017 are analyzed, and the results show that the ZTD effect of THE ERA5 reanalysis data derived in the small range area is not very ideal, but the accuracy of the PWV derived from ERA5 is better.