Tropospheric Delay Model Based on VMF and ERA5 Reanalysis Data

The global tropospheric zenith delay grid products of VMF1 and VMF3 (Vienna mapping functions) with different resolutions are used to calculate the tropospheric zenith delay of eight IGS (International GNSS Service) stations in China, and the accuracy of the two products under different interpolation methods is analyzed. As a result, the accuracy of utilizing different interpolation methods shows no obvious differences. The interpolation accuracy of the VMF3 grid model is slightly higher than that of the VMF1, and the interpolation accuracy of tropospheric delay is related to the elevation difference of grid points. In addition, according to ERA5 (the fifth generation of the Global Climate Information Analysis data set), the atmospheric stratification tropospheric delay is obtained, and a ZTD (the zenith tropospheric delay) height change grid model is constructed using the least squares exponential fitting method. The accuracy of the model is verified using the tropospheric delay product provided by the IGS. Finally, the constructed ZTD height change grid model is used as ZTD height reduction to solve the problem of large tropospheric delay errors in the VMF interpolation when the height change is large. The model accuracy of URUM station improve from 96.47 mm.to 32.97 mm (65.82%).

Automated summary

This study used the global tropospheric zenith delay grid products of VMF1 and VMF3 to calculate the tropospheric zenith delay of eight IGS stations in China and analyzed the accuracy of the two products under different interpolation methods. The results showed that there were no significant differences in accuracy when using different interpolation methods. The interpolation accuracy of the VMF3 grid model was slightly higher than that of the VMF1, and the interpolation accuracy of the tropospheric delay was related to the elevation difference of grid points. Additionally, a ZTD height change grid model was constructed using the least squares exponential fitting method, and its accuracy was verified using the tropospheric delay product provided by the IGS. The constructed model effectively reduced tropospheric delay errors in VMF interpolation when there was a large height change, with a significant improvement in accuracy at the URUM station.