Dependence of the Lunisolar Perturbations in the Earth Rotation on the Adopted Earth Model

Abstract

If no perturbation exists, the motion of the Earth around its center of mass would be a rigid rotation around a fixed axis in space with constant angular velocity.In fact, many perturbations disturb this ideal motion and produce variations in both the celestial orientation of the rotation axis and the Earth’s angular velocity.The mechanisms responsible for these perturbations are the changes in the total angular momentum due to external torques and also the changes in the inertia tensor of the Earth (due to deformations or motions of matter) or in the relative angular momentum in the terrestrial frame (due for instance to winds or to turbulent flow inside the core).