Earth Pole Motion Due to Nonstacionary Perturbations
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rth Pole Motion Due to Nonstacionary Perturbations L. D. Akulenko1 and A. A. Perepelkin2* 1
Ishlinsky Institute for Problems in Mechanics, Russian Academy of Sciences, pr. Vernadskogo 101, str. 1, Moscow, 119526 Russia 2 Moscow Aviation Institute (National Research University), Volokolamskoe sh. 4, Moscow, 125993 Russia Received March 20, 2019; revised March 25, 2019; accepted April 2, 2019
Abstract—A numerical analytical refined model of a short term forecast of the Earth’s pole motion is proposed. The model allows to increase the accuracy of predicting the coordinates of the pole with observed irregular effects in its motion. A numerical simulation of the oscillatory motion of the Earth’s pole is carried out in comparison with the data of observations and measurements of the International Earth Rotation Service, and the accuracy characteristics of the model are investigated. DOI:
Keywords: Earth’s pole oscillations, Earth’s rotation, gravitational tidal disturbance, forecast of Earth’s rotation parameters.
INTRODUCTION Along with the construction of an autonomous model for calculating the motion of the Earth’s pole, of interest is the development of adaptive models taking into account the correction of quasiconstant model coefficients (amplitudes of the main harmonics), which are subject to changes due to the unsteadiness of disturbing factors affecting the motion of the Earth’s pole [1–5]. Such models are not completely autonomous (they can be considered autonomous in the time interval specified by the requirements of the problem), but they have significantly greater forecasting accuracy. In practice, the choice of a forecasting model is the result of a compromise between the accuracy of the forecast, the duration of the forecast interval (autonomy) and the number of determining parameters, i.e. computational complexity of the model. In [3–5], the accuracy characteristics of low-parameter numerical analytical models of the oscillatory motion of the Earth’s pole are studied in a first approximation. The Earth pole motion model considered in [6] is a natural refinement of the previously developed main (two-frequency) model of its oscillations and takes into account variations in the amplitudes of the Chandler and annual components caused by lunar disturbance. In this article, on the basis of a numerical analytical approach, a model of the Earth’s pole oscillations is proposed, which allows one to improve the accuracy of predicting its trajectory during the irregular effects previously noted by the authors [4, 5], caused by the variability of the amplitudes of the fundamental harmonics of the oscillatory process. When changing the ratio of the amplitudes of the main components of the oscillations of the Earth’s pole, considered, for example, in [6], its motion differs significantly from the motion “with average parameters”. This leads to the need to modify the forecast model of its movement for the corresponding time intervals. 1. VARIATIONS OF THE INERTIA TENSOR OF THE FREE MOVEMENT OF THE DEFORMABL
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