Toroidal Magnetic Flux Budget in Mean-Field Dynamo Model of Solar Cycles 23 and 24

Abstract: We study the toroidal magnetic flux budget of the axisymmetric part of a 3D mean-field dynamo model of Solar Cycles 23 and 24. The model simulates the global solar dynamo that includes effects of the formation and evolution of bipolar magnetic regions emerging on the solar surface. Our analysis shows that the hemispheric magnitude of the net axisymmetric toroidal magnetic field in the bulk of the convection zone is partly defined by the surface parameters of the differential rotation and the axisymmetric radial magnetic field. The contribution of the rotational radial shear to the net axisymmetric toroidal field production has the same magnitude and it goes nearly sin-phase with the effect of the latitudinal differential rotation. For our model, the effect of the radial shear to the net axisymmetric toroidal magnetic field is determined mostly by the near equatorial regions that are slightly above and below the bottom of the convection zone. Also, we find that the toroidal field generation rate depends strongly on the latitudinal profile of the axisymmetric radial magnetic field near the poles. We find that the magnitude of the axisymmetric toroidal flux generation rate in the 3D dynamo model is by about 10 percent higher than in the axisymmetric 2D mean-field dynamo model, due to the bipolar active regions.