Sunspot Count Periodicities in Different Zurich Sunspot Group Classes since 1986

Abstract

In this study, we used two methods to investigate the periodic behavior of sunspot counts in four categories for the time period January 1986-October 2013. These categories include the counts from simple (A and B), medium (C), large (D, E, and F), and final (H) sunspot groups. We used: i) the Multi-taper Method with red noise approximation, and ii) the Morlet wavelet transform for periodicity analysis. Our main findings are: (1) the solar rotation periodicity of about 25 to 37 days, which is of obvious significance, is found in all groups with at least a 95% significance level; (2) the periodic behavior of a cycle is strongly related to its amplitude and group distribution during the cycle; (3) the appearance of periods follow the amplitude of the investigated solar cycles, (4) meaningful periods do not appear during the minimum phases of the investigated cycles. We would like to underline that the cyclic behavior of all categories is not completely the same; there are some differences between these groups. This result can provide a clue for the better understanding of solar cycles.

Accepted Solar Physics, 2014

Cited by in corpus (4)

• Solar-Cycle Characteristics in Kodaikanal Sunspot Area: North--South Asymmetry, Phase Distribution and Gnevyshev Gap
• Short-Term Variations in the Equatorial Rotation Rate of Sunspot Groups
• Temporal evolutions and quasi-periodic variations present in the sunspot number and group sunspot area data measured at Kodaikanal Observatory for solar cycles 14 to 24
• Equivalence relations between the Cortie and Zurich sunspot group morphological classifications