GNSS-derived PWV and comparison with radiosonde and ECMWF ERA-Interim data over mainland China

Abstract

Precipitable water vapour (PWV) is a key factor for monitoring climate and the hydrological cycle. Here, PWV is calculated using 249 ground-based GNSS stations derived from the Crustal Movement Observation Network of China (CMONOC). Zenith total delay (ZTD) is estimated using the GAMIT/GLOBK (Ver. 10.4) and the zenith hydrostatic delay (ZHD) is calculated using the layered European Centre for Medium-Range Weather Forecasting (ECMWF) ERA-Interim data. The GNSS-derived ZTD is validated using the radiosonde and ECMWF data with the root mean square errors (RMSE) of 19.1 mm and 12.5 mm, respectively. The ECMWF-derived surface pressure (Ps) used to calculate the ZHD and the weighted mean temperature (Tm) calculated based on the layered ECMWF data are also evaluated using radiosonde data with RMSE values of 1.14 hPa and 1.24 K, respectively. Consequently, the final CMONOC-derived PWV at 249 stations is obtained and compared with radiosonde-derived and ECMWF-derived PWV while the RMSE values are 1.38 mm and 1.30 mm, respectively. The two-dimensional (2-d) PWV image derived from CMONOC is also compared with that from ECMWF, which shows good consistency across different seasons.