Solar Influence on Chandler Period

The Chandler wobble (CW) is a free rotational mode of the Earth associated with its dynamical ellipticity.In the absence of external force, the CW would have a period of about 433 days.The Chandler wobble is excited by a combination of atmospheric and oceanic processes, with the dominant excitation mechanism being ocean-bottom pressure fluctuations, caused by ocean circulation and variations in temperature, salinity, and winds.The most important energy sources of all atmospheric and oceanic processes are the solar activity cycles, so the solar cycles affect climatic system and angular momentum of atmosphere and ocean, followed by polar motion and Chandler period variations.The Chandler period variations are determined from the coordinates of polar motion for 1860-now from the solution C01 of the IERS.The centennial, decadal and interannual harmonics of solar activity are determined by the Method of Partial Fourier Approximation of time series of the Total Solar Irradiance (TSI), Sunspot Numbers (SSN) and North-South Solar Asymmetry (N-S SA).The long-term variations of CW period are compared with corresponding cycles of N-S SA.The decadal and interannual oscillations with periods above 6yr of CW have good agreement with the TSI cycles in several frequency bands.The short-term CW oscillations have good agreement with SSN cycles in two bands of periodicity between 3 and 4 years.It is remarkable that the CW grand minimum around 1930 is strongly connected with all solar harmonics with dominating influence of long term N-S SA variations (periodicity 78-156yr, CW period decrease -6d) and TSI variations (periodicity 39-52yr, CW period decrease -10d).The TSI influence on CW period variations is non-linear and frequency dependent.The value of CW period increase during the warming cycles of solar activity and decrease during some solar minima.