Left panel: histograms of the vertical magnetic field component, B_Z, in the stationary dynamo phase of the run B20. The histograms in red colors refer to heights below the solar surface from −420 to 0 km; the histograms in blue colors refer to heights above the solar surface from 0 to 420 km. The black curve corresponds to the histogram of B_Z at the solar surface τ₅ = 1. Right panel: same, for run R20.