Detection of the mutual periodical changes in the Earth rate of rotation and the solar activity by singular spectrum analysis

During the examination of regular and irregular changes in the Earth's rate of rotation and solar activity we noticed that there are a lot of repeating matches of the extreme values of these two phenomena in the sense that minimums in one quantity match maximums in the other quantity and vice versa. We used Singular Spectrum Analysis as a modern tool in spectral analysis to detect some harmonics in both phenomena that have very similar periods. The results indicate that there are some periodical changes in these two phenomena that could be connected and some of these periods which are quite long are already identified by some researches of the solar activity.