Magnetic power spectra for Run M7. Panel a: spectra of the mean radial magnetic field B̄_r (solid) and the mean azimuthal magnetic field B̄_φ (dashed) near the surface (r = 0.98; black), in the middle of the convection zone (r = 0.72; blue). Panel b: spectra of near the surface (r = 0.85; red) and averaged over radius (black). All spectra are obtained for each latitude and then averaged. The peaks in a correspond to magnetic cycle periods and in b to activity cycles periods. The solid vertical lines indicate the cycle periods determined from the weighted average of the spectra in a (P_cycl), the dashed lines indicate the cycle periods determined from the weighted average of the spectra in b ( P̃_cycl).