Study of the dynamics of changes in the parameters of the Chandler pole oscillation in the interval 1975.0—2011.0

Zalivadny, NM, Khalyavina, LY
Kinemat. fiz. nebesnyh tel (Online) 2024, 40(5):3-22
Language: Ukrainian
Abstract: 

A structural analysis of the time series of pole coordinate changes (version C01 IERS) was carried out for the period 1975.0—2011.0 based on the nonlinear least squares method. Average estimates of the parameters of the main components of the pole movement — Chandler, annual, and semiannual waves — were obtained for this interval. The obtained values of periods T and amplitudes A of the main components are as follows: Chandler — T = 433.49 ± 0.22 days, A = 160 ± 3 mas; annual — T = 365.19 ± 0.37 days, A = 93 ± 5 mas; semiannual — T = 183.03 ± 0.34 days. A = 4 ± 2 mas. In the time series changes in pole coordinates were examined, focusing on the manifestation of the Chandler wobble. This study delved into the dynamic alterations of oscillation parameters (including amplitude, period, phase, quality factor). Changes in the parameters of the Chandler oscillation show their interdependence. The correlation coefficient between phase and period variations is +0.94, and a similar relationship is observed between phase and amplitude variations with a correlation coefficient of +0.88. It is shown that the phase change precedes the amplitude and period changes. This behavior of the parameters of the Chandler oscillation suggests that changes in the period and amplitude should be considered as a consequence of changes in the phase. It was observed that an increase in the Chandler wobbles amplitude correlates with a decrease in the attenuation decrement, showing a correlation coefficient of –0.98. These findings align with the statistical regularities articulated by Melchior, indicating: a) non-constancy of the Chandler wobble period over time; and b) proportional changes between period and amplitude. Thus, for the studied interval, preference should be given to the one-component complicated model of the Chandler pole movement with a variable period.

Keywords: Chandler wobble, Melchior’s laws, polar motion, quality factor