Temporal variations of the gravity field and Earth precession-nutation

TL;DR

This paper investigates how space geodetic measurements of Earth's gravity field variations can improve understanding of Earth's precession and nutation, focusing on the influence of geophysical mass redistributions on Earth's orientation parameters.

Contribution

It introduces a method combining space geodetic data, especially CHAMP, to refine Earth's precession-nutation models by accounting for gravity field temporal variations.

Findings

Gravity variations relate to Earth's orientation changes.

CHAMP data enhances sensitivity to gravity field fluctuations.

Preliminary results suggest improved precession-nutation estimates.

Abstract

Due to the accuracy now reached by space geodetic techniques, and also considering some modelisations, the temporal variations of some Earth Gravity Field coefficients can be determined. They are due to Earth oceanic and solid tides, as well as geophysical reservoirs masses displacements. They can be related to the variations in the Earth's orientation parameters (through the inertia tensor). Then, we can try to improve our knowledge of the Earth Rotation with those space measurements of the Gravity variations. We have undertaken such a study, using data obtained with the combination of space geodetic techniques. In particular, we use CHAMP data that are more sensitive to such variations and that complete the ones already accumulated (for example with Starlette and LAGEOS I). In this first approach, we focus on the Earth precession nutation, trying to refine it by taking into account the temporal variations of the Earth dynamical flattening. The goal is mainly to understand how Geodesy can influence this field of science. Like this, we will be able to compare our computation with up to date determinations of precession nutation.