Cyclic and secular variations sunspot groups with various scales

Abstract

Data from the Greenwich Catalog and its NOAA-USEF extension are used to analyze the spot-formation activity on the Sun separately for small (S 500 msh) sunspot groups. The relationship between the numbers of groups with various areas changes with time. This is determined primarily by numerous small-area groups. Over nearly 150 years, periods have been observed when the relative number of large groups has increased (Cycles 18 and 19), as well as extensive periodswhen the number of small groups has grown. As a rule, the latter correspond to low activity cycles. The observed relations indicate the possible interaction of two independent mechanisms in the spot-formation activity of the Sun. A deep dynamo controls the variations of the number of small spots, while the formation of large spots is determined by processes in sub-surface layers.