(A) Time series of magnetic energy (blue) and the toroidal magnetic field at mid-latitude and at R = 0.7 R_⊙ (red). (B) Time series of smoothed full-cycle amplitude A_k (see text for definition). The gray shading corresponds to the time span plotted in (A). The red and green dots represent cycles higher and lower (respectively) than the A_k-threshold chosen to delineate epochs of strong and normal mode of dynamo operation. The choice of threshold value is based on a break in the slope of the |A_k| histogram, plotted in (C). Panels D and E show histograms of strong mode durations and inter-event waiting times, equivalent to the duration distribution for normal dynamo operation.