Mean of j² as a function of height at the end of the T1 (solid red), T2 (solid green) and T3 (solid blue) simulations. We also show the mean of the perturbed magnetic field strength for the T1 (dashed red), T2 (dashed green) and T3 (dashed blue) simulations. The solid black line shows the mean of the initial magnetic field strength as a function of height. For all variables we have normalised by their respective maxima and taken logarithms.