Earth’s modern polar motion analysis theoretical aspects

The article focuses on exploring the theoretical aspects of the phenomenon that characterizes the modern movements of the Earth’s poles. As scientific progress advances at an ever-increasing pace, technologies and interpretations of various phenomena evolve. This also applies to the phenomenon defining the movement of the Earth’s poles. In the past century, this phenomenon was primarily associated with the motion of the Earth’s rotation axis within its body. However, improvements in measurement accuracy and, consequently, advancements in precession and nutation models have led to the exclusion of short-period nutation components from the celestial pole motion model. Thus, the modern interpretation of the pole movement phenomenon has come to include these short-period nutation components as well. To establish a clear understanding of what exactly is meant by the phenomenon of pole movement, the article provides a detailed characterization of its modern definition. Existing datasets characterizing the current motion of the poles are analyzed, and parameters are identified that can be used for numerical analysis of data representing the time series of Earth’s pole motion. Typically, when studying pole motion, efforts are made to determine the recurrence period of certain cycles, such as the well-known Chandler period (1.2 years) and the annual period (1 year). However, this article focuses more on identifying additional numerical parameters characterizing the rotation of the axis. These parameters include indicators such as the average angular velocity of rotation, the average rotation period, and the direction of the averaged pole’s movement. The purpose of the article is to identify polar motion parameters that enable quantitative and qualitative analysis of this motion. The article considers the classical approach to interpreting Earth’s polar motion and highlights aspects of its modern interpretation. Additionally, available data sources containing information on polar motion over recent decades are described. Keywords: Earth’s polar motion, precession, nutation, time series.