Study on GNSS zenith tropospheric delay spatial interpolation in -Beijing-Tianjin-Hebei region

The difference of zenith tropospheric delay (ZTD) during different periods affects the accuracy of InSAR deformation; changes in precipitable water vapor (PWV) affect weather changes. The ZTD has a good correlation with PWV, so it is necessary to carry out an interpolation study of GNSS ZTD. Taking Beijing-Tianjin-Hebei region as an example, the spatial interpolation of ZTD is studied for GNSS ZTD. Firstly, the comparative analysis of ZTD and PWV in GNSS is carried out. The two have significant positive correlation characteristics, and the correlation is larger than 91.7％. The feasibility of ZTD to replace PWV is demonstrated. Then, using the inverse distance weighting method, that of 12 groups of GNSS stations in Beijing-Tianjin-Hebei region from September 2016 to August 2017 are spatially interpolated. The spatial interpolation accuracy is verified by extracting the ZTD of the interpolation points and that of the GNSS station. The average deviation of the annual data is 1.12 cm, the root mean square error is 0.89 cm; the average deviation of non-precipitation is 1.25 cm, the root mean square error is 0.82 cm, and the average deviation of precipitation is 1.08 cm, the root mean square error is 1.38 cm. The GNSS ZTD spatial interpolation results in as a Beijing-Tianjin-Hebei plain area meet the meteorological requirements, which can provide as a reference for meteorological forecasting and InSAR atmospheric correction.