Testing and forecasting the time series of the solar activity by   singular spectrum analysis
  To study and forecast the solar activity data a quite perspective method of singular spectrum analysis (SSA) is proposed. As known, data of the solar activity are usually presented via the Wolf numbers associated with the effective amount of the sunspots. The advantages and disadvantages of SSA are described by its application to the series of the Wolf numbers. It is shown that the SSA method provides a sufficiently high reliability in the description of the 11-year solar cycle. Moreover, this method is appropriate for revealing more long cycles and forecasting the further solar activity during one and a half of 11-year cycle. 
A. Loskutov, I. A. Istomin, K. M. Kuzanyan and O. L. Kotlyarov