A SOLAR-CYCLE TIMING PREDICTOR - THE LATITUDE OF ACTIVE REGIONS

The Schatten and Sofia (1987) 'dynamo theory' prediction for the amplitude of smoothed annual sunspot number in the present solar cycle, No. 22, of 170 ± 25 was predicted to peak in 1990 ± 1 year. This peak was earlier and larger than most other estimates made in early 1987. New observational evidence shows sunspot values rising very rapidly, generally supporting the 'exceptionally large' cycle predicted, however, solar cycle 22 appears even more exceptional than expected, in that the early cycle rise has exceeded all previous cycle increases. We use a 'Spörer butterfly' method to examine solar cycle 22. We show from the latitude of active regions, that the cycle can now be expected to peak near November 1989 ±8 months, basically near the latter half of 1989. © 1990 Kluwer Academic Publishers.