A rotational ellipsoid model for solid Earth tide with high precision

TL;DR

This paper introduces a high-precision geometric model of solid Earth tide using a rotating ellipse, improving the accuracy of tidal displacement predictions compared to existing models.

Contribution

The paper presents a novel geometric model that determines the ellipsoid's geometry and tidal displacement through a rotating ellipse, validated with 23-year gravity data.

Findings

The model achieves an average RMS deviation of 6.47 μGal, significantly better than the 30.77 μGal of the current model.

The geometric model provides more accurate tidal displacement estimates, enhancing applications in geodesy and geophysics.

Validation with long-term gravity data demonstrates the model's high precision and practical utility.

Abstract

Solid Earth tide represents the response of solid Earth to the lunar (solar) gravitational force. The yielding solid Earth due to the force has been thought to be a prolate ellipsoid since the time of Lord Kelvin, yet the ellipsoid's geometry such as major semi-axis's length, minor semi-axis's length, and flattening remains unresolved. Additionally, the tidal displacement of reference point is conventionally resolved through a combination of expanded potential equations and given Earth model. Here we present a geometric model in which both the ellipsoid's geometry and the tidal displacement of reference point can be resolved through a rotating ellipse with respect to the Moon (Sun). We test the geometric model using 23-year gravity data from 22 superconducting gravimeter (SG) stations and compare it with the current model recommended by the IERS (International Earth Rotation System) conventions (2010), the average Root Mean Square (RMS) deviation of the gravity change yielded by the geometric model against observation is 6.47 \mu Gal (equivalent to 2.07 cm), while that yielded by the current model is 30.77 \mu Gal (equivalent to 9.85 cm). The geometric model will greatly contribute to many application fields such as geodesy, geophysics, astronomy, and oceanography.