Combining the Tide Gauge Stations and GPS/GLONASS Observations to Validate Global and Regional Ocean Tide Models around China Coast

Ocean tide loading (OTL) correction is becoming more and more crucial in high precision geodetic data processing. The published global ocean tide models show good agreement in deep oceans and exhibit differences in complex coastal areas, along with subsequent OTL displacement modeling differences. In order to select a suitable high precision ocean tide model for China’s coastline, both the tide gauge stations and multifrequency Global Navigation Satellite System (multi-GNSS) observations are used for validating eight global ocean tide models and a regional ocean tide model. First, 18.6 year’s tide gauge data were employed to generate the harmonic parameters to evaluate the accuracy of 9 ocean tide models. The DTU10 model shows better agreement with tide gauge stations. Second, combining the Global Positioning System (GPS) and global navigation satellite system (GLONASS) kinematic precise point positioning (PPP) was improved based on the algorithm of GPS kinematic PPP to estimate the effects of three-dimensional (3D) OTL displacements. Then, continuous observations of 23 coastal sites from the Crustal Movement Observation Network of China from January 1, 2016 to December 31, 2019 were collected to generate 3D OTL displacement amplitudes and phase lags of 8 constituents using GPS/GLONASS solutions and harmonic analysis. By comparison with DTU10 model predictions, the results present that the combined GPS/GLONASS-derived OTL displacement model showed good consistency with the model predictions in all three components. Third, the GPS/GLONASS-derived OTL displacement estimates were taken as reference to calculate the root mean square (RMS) misfit with model values from 9 ocean tide models. The results show the DTU10 model agreed with the multi-GNSS-derived OTL displacement estimates best in all three components. The RMS misfits of all constituents are less than 1.8, 1.3, and 1.8 mm in the vertical, east, and north directions, respectively. Finally, through comparing the correction effects from different model predictions on the coordinate time series of the GNSS stations, the results also show that the DTU10 model correction effect in the GNSS position time series was better than that of other global or regional ocean tide models. That DTU10 model had good adaptability in the China coast areas was proven, so that it can be recommended for more data processing, such as leveling, gravity, and other geodetic data processing.