Abstract
The smoothed monthly sunspot numbers of the previous 22 complete sunspot cycles are normalized in time domain, and then an eigen mode analysis is carried out to draw the principle factors (or components) in the cycles. The results show that the main characteristics of the solar cycles can be described fairly well by the first 5 eigen modes. The obtained eigen modes are used to predict the declining phase of cycle 23 on the basis of the data prior to its maximum. The prediction indicates that cycle 23 will last for 127 months to December 2006, with the minimum of 6.2.
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Xu, W. Normalization of sunspot cycles and eigen mode analysis. Sci. China Ser. A-Math. 45 (Suppl 1), 4–11 (2002). https://doi.org/10.1007/BF02889677
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DOI: https://doi.org/10.1007/BF02889677