Understanding solar cycle variability
arXiv:1705.10746 · doi:10.3847/1538-4357/aa767a
Abstract
The level of solar magnetic activity, as exemplified by the number of sunspots and by energetic events in the corona, varies on a wide range of time scales. Most prominent is the 11-year solar cycle, which is significantly modulated on longer time scales. Drawing from dynamo theory together with empirical results of past solar activity and of similar phenomena on solar-like stars, we show that the variability of the solar cycle can be essentially understood in terms of a weakly nonlinear limit cycle affected by random noise. In contrast to ad-hoc `toy models' for the solar cycle, this leads to a generic normal-form model, whose parameters are all constrained by observations. The model reproduces the characteristics of the variable solar activity on time scales between decades and millennia, including the occurrence and statistics of extended periods of very low activity (grand minima). Comparison with results obtained with a Babcock-Leighton-type dynamo model confirms the validity of the normal-mode approach.
ApJ, accepted
References in corpus (7)
- Generalized investigation of the rotation-activity relation: Favouring rotation period instead of Rossby number
- The crucial role of surface magnetic fields for the solar dynamo
- Solar Cycle Propagation, Memory, and Prediction: Insights from a Century of Magnetic Proxies
- Effects of the scatter in sunspot group tilt angles on the large-scale magnetic field at the solar surface
- Level and length of cyclic solar activity during the Maunder minimum as deduced from the active day statistics
- An update of Leighton's solar dynamo model
- Oscillator models of the solar cycle: Towards the development of inversion methods