Solar Physics Division Meeting 2000, June 19-22 Session 2. The stability of the identified cycles is examined by testing different fractions from the time interval covered by the series. The interpretation of the long-term solar variability is far from simple. On the other hand, between 296 AD and 1000 AD stable and statistically reliable cycles are not identified and the variations are irregular rather than cyclic.
Weak periodicities are present but well bellow the noise level.
This modulation in the features of the solar variability indicated in the Schove series might be connected with the influence of a much longer periodicity than than those discussed here, in particular the possible 2400-year cycle.