Variations in the cyclic characteristics of solar magnetic activity on long time scales

Abstract

Prolonged variations in the duration of the Schwabe-Wolf (~11 years) and Suess (~200 years) cycles have been analyzed using different experimental data. It was shown that the duration of the Schwabe-Wolf cycle on a 2000 year time scale varied monotonically (on average, increasing) and cyclically (with a period of several hundred years); periods of 10.4, 11.0, and 11.4 years predominate on the occurrence fre quency histogram. The Suess cycle duration was 200-290 years during the Holocene and tended to increase in the past. This was accompanied by cyclic variations with a period of 2300-2500 years corresponding to the Hallstatt cycle. Arguments for the assumption that the Suess cycle duration decreased by a factor of more than 1.5 over the past half billion years are presented. This may indicate that the solar rotation characteristics and convection zone parameters varied on long time scales during the Sun's evolution on the main sequence.