The solar-cycle period-amplitude relation as evidence of hysteresis of the solar-cycle nonlinear magnetic oscillation and the long-term (55 year) cyclic modulation.
Abstract
A new dynamical model of the solar cycle has predicted that the cycle should have a hysteretic nature: the behavior of each 11 year cycle should depend on previous cycles. In the light of this new understanding of the dynamical mechanism of the solar cycle, Waldmeier's (hypothetical) law was examined as a yet unexplained characteristic of the cycle by studying the observed sunspot frequency curve. Contrary to this hypothetical law, however, it was found that sunspot cycle curves did not form a single-parameter family characterized by the maximum amplitude of the cycle. The evolutionary trajectories in period-amplitude phase space verified the hysteretic nature of the observed cycle and revealed long-term (55 year instead of the previously claimed 80 year) periodic modulations, called here 55 year grand cycles. Each 55 year grand cycle forms a loop in the phase space, and the characteristics of each 11 year cycle depend on its position in the ascending or descending phase of the grand cycle. This new law was analyzed by the nonlinear multiple-period dynamo oscillation model which has predicted the hysteretic nature. The era from cycle 11 to cycle 13 turned out to be an anomalous one characterized by alternating amplitudes for odd and even cycles. Cycles 1620 seem to constitute one grand cycle. If this is true, cycle 21 would be the beginning of another grand maximum and the model predicts that its duration would be short. Subject headings: hydrodynamics - hydromagnetics - Sun: activity - Sun: sunspots
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 1979
- DOI:
- 10.1086/156812
- Bibcode:
- 1979ApJ...227.1047Y
- Keywords:
-
- Long Term Effects;
- Magnetic Variations;
- Solar Magnetic Field;
- Sunspot Cycle;
- Amplitudes;
- Dynamic Models;
- Dynamo Theory;
- Hysteresis;
- Oscillations;
- Solar Physics;
- Solar Activity Cycles:Sunspots