Analysis of Polar Motion Variations from 170-year Observation Series

TL;DR

This study extends the analysis of polar motion over 170 years using innovative methods, revealing new phase jumps and an 80-year cycle, enhancing understanding of Earth's rotational variations.

Contribution

It introduces a novel approach using latitude series from a single observatory to extend polar motion data back to 1840, uncovering new features in long-term variations.

Findings

Detection of two new large phase jumps in 1840s and 2000s

Identification of an 80-year period in polar motion variations

Confirmation of low-frequency oscillations using multiple methods

Abstract

This work is devoted to investigation of low frequency variations in Polar motion (PM). It has been shown that the main PM features can be effectively investigated using not only time series of the Pole coordinates, but also using series of latitude variations obtained from observations at one observatory. Such an approach allows us to increase the length of observation series available for analysis. In our study, we extended the IERS PM series back to 1840. We investigate trends and (quasi) harmonic oscilla-tions with periods from one year to decades. The main results were obtained making use of the Singular Spectrum Analysis. Other methods were also used for specific analysis and independent check. The most interesting results are detection of two new large phase jumps in the 1840s and 2000s, and revealing of 80-year period in the PM variations.