Contributions to the Earth's rotation due to tidal mass redistribution

• Autores: Baenas, T.; Escapa, A.; Ferrándiz, J. M.
• Año de publicación: 2025
• Idioma: inglés
• Tipo de recurso: documento de conferencia
• Materia: Ciencias Astronómicas; Tidal mass redistribution; Earth rotation dynamics; Love numbers theory
• Institución: Universidad Nacional de La Plata

The mass redistribution of tidal origin is due to the gravitational attraction exerted by the Moon and the Sun on the Earth. This redistribution modifies the potential energy of the mechanical system, thereby affecting the Earth's rotation. In recent years [1-3] we have derived analytical formulae to quantify and describe the contributions of this process to precession and nutation motions, as well as to the secular changes in the length of day (LOD). A key component of this calculation is the modeling of the Earth's deformation. It relies on the Love numbers theory-more specifically, on complex Love functions-, which depend on the frequencies arising from a Fourier-type decomposition of the Earth's anelastic response. Consequently, the numerical evaluation of our formulae requires standardized datasets that provide the corresponding Love numbers for each perturbing frequency. We review the procedure necessary to obtain analytical expressions for the precession, nutation, and secular changes in LOD. This is accomplished through the Hamiltonian formalism of the non-rigid Earth rotation. The numerical value of the amplitudes and rates are obtained by using the Love number sets corresponding to solid Earth tides (IERS Conventions 2010) and direct ocean tides. The results show that both sets must be considered given nowadays current accuracy requirements. These findings underscore the importance of integrating all relevant tidal contributions into a unified and updated framework.
Facultad de Ciencias Astronómicas y Geofísicas