Wavelet analysis of the variable Chandler wobble

We develop a new wavelet analysis technique, namely wavelet amplitude‐period spectrum (WAPS) to study the variations of the Chandler wobble (CW). The variable period and amplitude of the CW during 1900–1990 are quantified by using the WAPS technique. We show that the double‐frequency spectrum of the CW is related to the large variation in its period with respect to time. We find that amplitude and period of the CW clearly fit exponential laws during 1912–1928 and 1936–1948, corresponding to the strong damping and the strong excitation respectively. Our study suggests that the excitation and damping of the CW might well be in an equilibrium status during 1962–1990.