Estimation of Displacements Caused by Ocean Tide Loading Using Improved GPS Kinematic Precise Point Positioning Technique: A Case Study in Hong Kong, China

Compared with very long baseline interferometry (VLBI) and superconducting gravimeter (SG) techniques, Global Positioning System (GPS) technique has the advantages of global high-resolution coverage, long-term continuous observations, and low environmental impact to determine the ocean tide loading (OTL) displacement, which can provide a technical means to establish the ocean tide models and theory significance and reference for studying the OTL effect. In order to establish the regional OTL displacement model, the GPS kinematic precise point positioning (PPP) was used to determine the OTL displacement parameters. Three-dimensional ocean tide loading displacements of eight constituents at 11 sites in Hong Kong with eight years of continuous GPS observations are estimated. Comparing the RMS misfit of the model values, we found that the accuracy of K₂ and K₁ constituents are worst and the others' RMS are smaller than 2 mm. Comparing our results with the kinematic PPP and static PPP results, we found that our improved kinematic PPP can significantly improve the accuracy of K₁ constituent. And the accuracy of 8 constituents derived by our method can reach the same accuracy as the kinematic PPP results, for K₁ constituent, the accuracy of our method results is slightly better than the kinematic PPP results. Finally, using the least square quasi method to establish the GPS regional OTL displacement model can provide the reference for OTL effect correction in the coastal area which are lack of high accuracy local tide model.