The dominant effects in the mean magnetic field evolution. Top row, from left to right: Ω effect , toroidal α effect , toroidal turbulent diffusion , mean radial and latitudinal field , . White: Field lines of mean poloidal field . Middle row: radial and latitudinal α effect , radial and latitudinal turbulent diffusion , mean toroidal field . Bottom row: components of rsinθ∇Ω. We note that the effects are computed with at the halfway point of a typical activity cycle with positive (cf. Fig. 13, top), but with the time-averaged transport coefficients (see Sect. 4.2).