Possible influence of the 11-year solar cycle on length-of-day change

Earth's variable rotation with its complex state of motion and excitation mechanism that indicates complex overall geodynamical process of the Earth system, reflects interactions among the solid Earth, atmosphere and oceans, etc. Solar activity has been found to be strongly correlated with some geophysical processes in the Earth system. In order to investigate the affects of solar activity on Earth's rotation using the wavelet transform technique, the yearly Earth's length-of-day (LOD) time series spanning hundreds of years is used to investigate the presence of the 11-year periodic component. The results show obvious fluctuation in the LOD variations. We suggest that the solar activity plays an important role in the oscillation of the Earth's rotation, and that there is a possible relationship between solar activity and Earth's rotation on decadal time scale.