For each simulation run, the peak of the mean unsigned magnetic flux density over the polar caps at the end of solar cycle n vs the maximum total surface coverage by sunspots over cycle n + 1, where n ranges from 15 to 21. We excluded solar cycle 14 as the end of this cycle occurred at the start of the simulation, and is therefore sensitive to the arbitrary initial condition. The crosses and lines denote the individual cycle values and the corresponding linear fit. The Pearson’s correlation coefficient, R, is indicated (see Sect. 3.2.3 for details).