Short-Term Period Variation of Relative Sunspot Numbers

Abstract

We use wavelet transform to analyze the daily relative sunspot number series over solar cycles 10–23. The characteristics of some of the periods shorter than ~600-day are discussed. The results exhibit not only the variation of some short periods in the 14 solar cycles but also the characteristics and differences around solar peaks and valley years. The short periodic components with larger amplitude such as ~27, ~150 and ~360-day are obvious in some solar cycles, all of them are time-variable, also their lengths and amplitudes are variable and intermittent in time. The variable characteristics of the periods are rather different in different solar cycles.