Chandler wobble: two more large phase jumps revealed

TL;DR

This study analyzes 163 years of Earth rotation data to identify significant phase jumps in the Chandler wobble, revealing two previously unreported large phase shifts in addition to the well-known 1920s event.

Contribution

It introduces a comprehensive analysis of long-term Chandler wobble phase variations using advanced digital filtering and transforms, uncovering new large phase jumps.

Findings

Identified two new large phase jumps in the 1850s and 2000s.

Confirmed the 1920s phase jump and its association with amplitude decrease.

Demonstrated the effectiveness of wavelet and Hilbert transforms in analyzing Earth's rotation anomalies.

Abstract

Investigations of the anomalies in the Earth rotation, in particular, the polar motion components, play an important role in our understanding of the processes that drive changes in the Earth's surface, interior, atmosphere, and ocean. This paper is primarily aimed at investigation of the Chandler wobble (CW) at the whole available 163-year interval to search for the major CW amplitude and phase variations. First, the CW signal was extracted from the IERS (International Earth Rotation and Reference Systems Service) Pole coordinates time series using two digital filters: the singular spectrum analysis and Fourier transform. The CW amplitude and phase variations were examined by means of the wavelet transform and Hilbert transform. Results of our analysis have shown that, besides the well-known CW phase jump in the 1920s, two other large phase jumps have been found in the 1850s and 2000s. As in the 1920s, these phase jumps occurred contemporarily with a sharp decrease in the CW amplitude.