Magnetic Fields and the Rotation of the Solar Convection Zone

Arguments are presented in favour of the conjecture that magnetic fields in the convection zone are concentrated, highly fragmented and passive to velocity fields (convection, rotation) with the only exception of the uppermost layers, where buoyancy becomes dominant. A firmer basis is given to the concept of an "anchor" or "coupling depth". It is concluded that large active regions have their origin in a region of dominating differential rotation at the lower boundary layer of the convetion zone from where they are injected into the convection zone proper. It is shown that this view is consistent with observations of the evolution of active regions and favours the cluster model of sunspots.