Amplitude and phase variations of Earth's Chandler wobble under continual excitation

We demonstrate a simple physical explanation for the cause of the well-known but so-far baffling behavior of the Chandler wobble during ∼1925 when it reached a near-zero amplitude and underwent a concurrent large phase jump. We do so by numerical Monte-Carlo simulations, designed based on simple physical reasoning, of the statistical behavior of the Earth's Chandler wobble under continual excitation. Rather than subscribing to the view that something extraordinary or anomalous had occurred to the Earth system sometime during the later half of the 1920s, we assert the scenario that the Chandler wobble excitation during that time happened to oppose and cancel the Chandler motion momentarily before starting anew the motion that became unrelated to its immediate past, hence manifesting as an apparent phase jump in the time series. The seemingly peculiar event was simply fortuitous by chance.

► We demonstrate a physical explanation for the baffling behavior of CW during ∼1925. ► In pendulum analogy, a phase jump would occur when a near-zero amplitude is reached. ► We do so by simulating the statistical behavior of the Earth's CW by Monte Carlo. ► The peculiar event was fortuitous and not something extraordinary that had occurred.