Latitude–time distributions of longitude-averaged radial magnetic field (a,b) alongside longitude integrated total helicity flux (c,d), and helicity flux associated individually with differential rotation (e,f), meridional velocity (g, h) and supergranular diffusion (i,j) for W18 and J11 respectively. We stress that these latitudinal distributions are not in themselves physically meaningful, since there is typically significant cancellation between different latitudes. The same colour scales are used for W18 and J11. Units are G for (a,b) and Mx² day⁻¹ for (c–j).