Skip to content


  • Article
  • Open Access

Sunspot variability and an attempt to predict solar cycle 23 by adaptive filtering

Earth, Planets and Space201450:BF03352090

Received: 7 July 1997

Accepted: 5 January 1998

Published: 6 June 2014


The series of annual mean relative sunspot numbers (Rz) for 1749–1996 is subjected to the recently developed methodology of Singular Spectrum Analysis (SSA). This technique also enables data-adaptive filtering of the individual spectral components. Low order autoregressive modelling of the components are combined to provide a basis for predicting the solar cycle 23.

The Rz series is largely dominated by a doublet with periods 11.13 and 10.35 yr. close to the nominal solar cycle periodicity, a longer period variation (~110 yr.) which is the envelope of the amplitude maxima and two clusters of periodicities centred around 8 yr. and 5.5 yr. The solar magnetic cycle has no detectable component. The predicted maximum for cycle 23 will have a magnitude of ~130 and the epoch of maximum is expected between late 2000 A.D. and early 2001 A.D.


Solar ActivitySolar CycleSunspot NumberMaximum Entropy MethodSolar Physic