On the mode of dynamo action in a global large-eddy simulation of solar convection

Its antisymmetric component, describing general turbulent pumping, is also extracted. The α-tensor so calculated reproduces a number of features already identified in local, Cartesian simulations of magnetohydrodynamical rotating convection, including an αΦΦ component positive in the northern solar hemisphere, peaking at high latitudes, and reversing sign near the bottom of the convection zone; downward turbulent pumping throughout the convecting layer; and significant equatorward turbulent pumping at mid latitudes, and poleward at high latitudes in subsurface layers.

We also find that the EMF contributes significantly to the regeneration of the large-scale toroidal magnetic component, which from the point of view of mean-field dynamo models would imply that the simulation operates as an α²Ω dynamo. We find little significant evidence of α-quenching by the large-scale magnetic field. The amplitude of the magnetic cycle appears instead to be regulated primarily by a magnetically driven reduction of the differential rotation.