Variations in the period of the sunspot cycle

Abstract

Using a wavelet analysis approach, subtle variations in the solar cycle period were extracted from the yearly means of the sunspot numbers. For the nominal eleven‐year solar cycle, the resulting estimates of the cycle's period are in good agreement with those given by Friis‐Christensen and Lassen. Longer period structures in the solar‐cycle, including the Gleissberg cycle, are also delineated by the wavelet analysis.