Estimating the Q of the Chandler Wobble in the Absence of Excitation

Abstract:

The quality factor Q of the Chandler wobble is a function of various dissipation processes acting in the Earth. Better estimates of the Q of the Chandler wobble can therefore be used to better understand these processes. Because of them, and in the absence of any excitation process, the amplitude of the Chandler wobble will freely decay with a time constant proportional to its Q. If a period of time can be found during which the Chandler wobble is not being excited but is instead freely decaying, then estimating the time constant associated with this free decay yields an estimate of the Q of the Chandler wobble. Observations of the Chandler wobble indicate that it was apparently freely decaying during the early 1960s. The Q associated with this apparent free decay is 32.5, somewhat lower than estimates of the Chandler wobble’s Q that have been obtained recently by modeling its excitation by atmospheric and oceanic processes. This may indicate that the Chandler wobble was, in fact, not in free decay during the early 1960s or, alternatively, that recent estimates of its Q based on modeling its excitation are biased high.