Dynamic processes in earth’s rotation parameters and tidal deformations on a rotating geoid

Abstract

Amplitude-frequency analysis of the Earth's rotaryoscillatory motion due to lunisolar gravita� tional and tidal perturbing torques is performed using methods of classical mechanics. Dynamic processes that occur in Earth's rotation parameters (ERP) and Earth's potential due to tidal deformations lead to distortions in Earth's shape and fluctuations in the gravitational field (1, 2). The results of the numerical modeling of oscillatory processes in the Earth's pole motion and variations in the second zonal harmonic δc20 of the geopotential are discussed. The amplitude and phase of oscillations of the Earth's pole are determined using the dynamic Euler-Liou� ville equations. The power spectral densities of the time series of Earth's polar coordinates are compared with those of δc20 variations in the geopotential. This harmonic is found to be a function of the amplitude and phase of the oscillatory process of the Earth's pole. 1. The study of temporal variations in the geopo� tential (2, 3) due to Earth's rotaryoscillatory motion is of scientific and practical interest. The observed ERP variations and variations in the Earth's gravita� tional field are highly interrelated; dynamic processes that lead to appreciable changes in both ERPs and geophysical phenomena have acquired the most detailed reflection in diurnal oscillations (4). The refinement of the Earth's gravitational field involves replacing the statistical geoid by a geoid that corresponds to the deformable shape of the Earth (due to oceanic and rigidbody tides and other factors). Due to increasing demands on the accuracy of the coordinatetime maintenance of navigation systems, investigations related to the refinement of the gravita� tional field and the shape of the Earth have developed intensively (2). Note that the modeling of tidal deformations on a rotating geoid can be used to reach high characteristics of atomic clock synchronization (the stability of atomic frequency is 10 -14 ) for objects that are located on different continents of the globe. Differential equations of the Earth's rotaryoscilla� tory motions with allowance for the harmonic struc� ture of the tidal coefficients were derived from the dynamic Euler-Liouville equations in the problem considering "a deformable Earth-Moon" system in the solar gravitational field (4):