PWV Inversion Method Based on GNSS and Non-Measured Meteorological Parameters and Accuracy Evaluation

Objectives Water vapor is one of the important components of the atmosphere, and its spatial and temporal variations are influenced by various meteorological factors such as temperature and pressure. Therefore, it is important to study the impact factors of water vapor inversion to obtain high-precision water vapor information.

Methods We study the method of precipitable water vapor (PWV) detection using global navigation satellite system (GNSS) and non-measured meteorological data (temperature and pressure) in China. First, we evaluate the data of temperature and pressure provided by the European Centre for Medium-Range Weather Forecasting(ECMWF) reanalysis v5(ERA5), and the zenith troposphere delay retrieved by GNSS. Then, different calculation models of atmospheric weighted mean temperature, named T_m, are analyzed to determine the optimal calculation model in China region. Finally, the theoretical error of PWV is derived from the error propagation theory, and the hourly resolution PWV is calculated using the non-measured data, and then the accuracy is evaluated.

Results The results show that the PWV obtained by GNSS in China region is in good spatial and temporal agreement with PWV derived from radio sounding and ERA5. The error of PWV during the rainfall period is slightly larger than that during the non-rainfall period. The theoretical error of PWV obtained by the proposed method is 2.0 mm, and the actual error is 2.1 mm.

Conclusions The inversion of PWV based on GNSS and non-measured meteorological parameters has high accuracy and it is important for studying the spatial and temporal variation and distribution of water vapor in China region.