High-precision solid Earth tidal geometry (Geo) model

Résumé fourni par la source

Solid Earth tides reflect the Earth’s elastic response to the tidal forces of the Moon and Sun. Studying these tides reveals Earth’s internal structure, response to ocean loading, and the relationship between tides and earthquakes. Solid Earth tides are also essential for understanding sea level changes and establishing international reference frames. Since the time of Lord Kelvin, scientists have generally accepted that the tidal forces of the Moon and the Sun induce periodic deformations on the solid Earth’s surface, which can be simulated using a superposition of ellipsoids. However, quantitative attempts to determine the geometric parameters of this ellipsoid, such as the lengths of the semi-major and semi-minor axes and the flattening ratio, have not been realized. This study aims to introduce and optimize a previously proposed high-precision solid Earth tide rotational ellipsoid geometric (Geo) model, which accurately characterizes solid Earth tidal displacements by imposing two rotational ellipsoids corresponding to the Moon and the Sun. Using data from four superconducting gravimeter (SG) stations, we optimized the Geo model’s parameters. Compared to mainstream models (Etideload and Solid/pyTMD), the Geo model demonstrated root mean square error, amplitude difference, phase lag difference and vector difference: 1.08 cm, 0.17 cm, 1.77° and 0.22 cm, respectively, versus 2.74 cm, 0.34 cm, 4.87° and 0.47 cm for Etideload, and 3.14 cm, 0.31 cm, 4.25° and 0.40 cm for Solid/pyTMD. The cotidal charts in areas with a denser distribution of SG stations (2°E–22°E，40°N–60°N) show that the results align with previous analyses, demonstrating the effectiveness of the Geo model in simulating solid Earth tide.

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