Flux-transport solar dynamo

A flux-transport solar dynamo couples toroidal and poloidal field generation through meridional advection, turbulent magnetic diffusion and possibly turbulent pumping. A common model uses the surface Babcock-Leighton mechanism, differential rotation near the tachocline, poleward surface circulation and an equatorward deep return flow. If advection dominates, circulation strongly influences the cycle period and migration; if diffusion dominates, diffusive coupling is important instead. Agreement with a butterfly pattern depends on the assumed transport geometry and coefficients, not merely on including a circulation term.