Persistent 22-year cycle in sunspot activity: Evidence for a relic solar magnetic field

We use the recently presented group sunspot number series to show that a pe rsistent 22-year cyclicity exists in sunspot activity throughout the entire period of about 400 years of direct sunspot observations. The amplitude of this cyclicity is about 10% of the present sunspot activity level. A 22-ye ar cyclicity in sunspot activity is naturally produced by the 22-year magne tic polarity cycle in the presence of a relic dipole magnetic field. Accord ingly, a persistent 22-year cyclicity in sunspot activity gives an evidence for the existence of such a relic magnetic field in the Sun. The stable ph ase and the roughly constant amplitude of this cyclicity during times of ve ry different sunspot activity level strongly support this interpretation.