Analysis of Influencing Factors and Accuracy Evaluation of PWV in the Loess Plateau

  Objectives  Atmospheric water vapor is one of the important components in troposphere. It is of great significance to study the factors and accuracy of influencing water vapor. This paper mainly studies the influencing factors of precipitable water vapor (PWV) in the Loess Plateau and evaluates its actual accuracy.

  Methods  Firstly, the pressure, temperature data of the fifth-generation atmospheric reanalysis data of ECMWF(ERA5)and global navigation satellite system(GNSS) derived zenith troposphere delay (ZTD) are evaluated. Secondly, according to the pressure and temperature data of ERA5 and ZTD data of crustal movement observation network of China (CMONOC), the PWV with 1-hour time resolution is calculated, and the theoretical error of PWV is deduced by using error propagation theory, and then the accuracy of PWV in the Loess Plateau is analyzed by comparing with the actual calculation error of PWV.

  Results  The results show that the average root mean square(RMS) and bias of GNSS-derived ZTD calculated by GAMIT/GLOBK and PANDA are 4.05 mm and -0.46 mm, respectively. The average RMS and bias of ERA5-provided pressure and temperature are 3.36 hPa / 1.97 K and -0.01 hPa / 0.04 K, respectively. The theoretical error of PWV in the Loess Plateau is 1.51 mm, and the actual error is 1.94 mm.

  Conclusions  The accuracy of PWV calculated in this paper is high, which is of great significance to the investigation of water vapor distribution and climate monitoring.