An Accuracy Comparison of Ocean Tide Models using a Global Superconducting Gravimeter Network

As ocean tides move massive quantities of water over the Earth, they cause fluctuations in local gravity which must be accounted for in the calibration of inertial guidance systems, measurement of geodetic surveys, and analysis of local hydrological processes. Ocean tide models, which contain detailed hydrodynamics and assimilated data, are used to predict these gravity fluctuations. We evaluate the accuracy of several common ocean tide models—including the DTU, EOT, FES, and TPXO families of models—against reference superconducting gravimeter (SG) data provided by the International Geodynamics and Earth Tides Service (IGETS) of the International Association of Geodesy (IAG). Other geophysical models, such as solid Earth tide and atmospheric loading, are removed from the SG data, and the reduced data is compared against ocean tide model predictions computed using the “Some Programs for Ocean-Tide Loading” (SPOTL) software suite developed by Scripps Institution of Oceanography. By comparing how well the various ocean tide models fit the SG data, these models can be ranked in terms of their absolute accuracy relative to the IGETS measurements, and such analysis can be used to inform model selection for downstream processing.