Intermittency and Phase Persistence in a Babcock-Leighton Model of the Solar Cycle

Abstract

We present and discuss a numerical simulation of the solar cycle based on the Babcock-Leighton mechanism of poloidal field regeneration by the surface decay of sunspots. The simulation includes low-amplitude stochastic noise and exhibits intermittency, i.e., quiescent episodes of strongly reduced amplitude irregularly interspersed between epochs of "normal" cyclic behavior. We show that the phase of the cycle can persist across these quiescent episodes, a feature normally not expected from intermittency. We ascribe this behavior to the regulatory influence of meridional circulation in the solar convective envelope, which is known to be the primary determinant of cycle period in this class of dynamo models. We also discuss similarities and differences between these results and the behavior of the sunspot cycle during the Maunder minimum of solar activity.