Chandler period estimated from frequency domain expression solving the Liouville equation for polar motion

Abstract

SUMMARY Accurate determination of the Chandler wobble (CW) period (TCW) and quality factor (QCW) is of great significance to our understanding of the Earth's dynamic figure parameters, elasticity, rheology and energy dissipation. TCW and QCW were typically determined in the time domain using the digital filter designed by Wilson; however, we developed an alternative method to estimate TCW in the frequency domain. We adopted the frequency domain expression solving the Liouville equation for polar motion (eq. 3 in the following) rather than the time domain to separate the free-damping CW and excited parts. Next, we substituted various excitation functions derived from the outputs of several general circulation models and selected monthly gravity models into the above frequency domain expression; hence we estimate TCW. The preferred TCW value using this method and the least difference combination mgm90 model is 430.4 ± 2.0 mean solar days. Comparing with previous studies within the error range, our results provide an independent way of estimating TCW.