Temporal and Spatial Variations of Zenith Tropospheric Delay Based on Ground GNSS

The characteristics of the Zenith Tropospheric Delay (ZTD) with temporal and spatial variations are analyzed by the measured data of 7 International GNSS Service (IGS) stations from 2015 to 2017. The results show that the ZTD distribution has obvious characteristics of cosine and seasonal characteristics. In addition, the value of ZTD is independent of station longitude, but is unequal for different latitudes and heights. At the same time, it is found that the variation trend of Saastamoinen model on single height variable is not consistent with reality. The results provide a reference for the establishment of a regional or global model without meteorological data.