Simulated magnetograms from Rempel & Cheung (2014) and their distributions. The left-hand column shows an example during the emergence phase, the middle panel shows the same at maximum flux, and the right panel shows this during the decay phase at the end of the simulation run. The red line shows the distribution of the positive field (the leading polarity), and the blue line shows the negative field (following). The best-fit lines between 20 and 1000 Gauss are shown as dashed lines, and their slopes are given in the legend.