  Results of analysis of long time variations of solar activities based on
monthly Wolf number series (1749-2011 years) are represented. Shown the
presence of stable oscillations in autocorrelation function for the Wolf
numbers series with a period near 42.5 years. The statistical model of
variations of autocorrelation function based on assumption of nonstationarity
process are constructed. The question of using the model to predict the solar
activity is discussed.
