Pixel-by-pixel comparison of subsurface toroidal flux density from model b, and observed surface toroidal field B_ϕ, for cycles 22, 23 and 24. We excluded cycle 21 from this analysis as it is heavily affected by the initial condition b = 0. Upper panel: results for the butterfly wings where flux emergence includes active region emergences. Middle panel: results for the quiet-Sun where the emergences are in the form of ephemeral regions. Bottom panel: both types of regions. The first two panels also show the error bars on the observed surface toroidal field obtained from the fitting procedure, in different colours to make them easier to distinguish. In the bottom panel we also show fits for both the quiet-Sun and butterfly wing data.