Prediction of the sunspot maximum of solar cycle 23 by extrapolation of spectral components

A simple method MEM-MRA, where spectral peaks are located by MEM (Maximum E ntropy Method) and about a dozen most prominent ones are used in MRA (Multi ple Regression Analysis) to estimate their amplitudes and phases, was appli ed to the sunspot number (Rz) series of 1748-1996. Spectral characteristics were different in the successive 3 intervals of 83 years each. Hence, for predictions, only data for the recent 83 years were considered relevant. Fr om the spectra for 1914-1996, the most significant peaks at 5.3, 8.3, 10.5, 12.2, 47 years were used for reconstruction. The match between observed an d reconstructed values was good (correlation +0.90). When extrapolated, the reconstructed values indicate a sunspot number maximum for the present sol ar cycle 23 as 140 +/- 9, to occur in year 2000 and for the next solar cycl e 24 as 105 +/- 9, to occur in year 2010-2011.