1205.4835 (V. V. Pipin)

The helicity-vorticity turbulent pumping of magnetic fields in solar convection zone    [PDF]

V. V. Pipin

We study the effect of the turbulent drift of the large-scale magnetic field that is resulted from interaction of the helical convective motions and the differential rotation in the solar convection zone. The principal direction of the drift corresponds to direction of the large-scale vorticity vector. Thus, the effect produce the latitudinal transport of the large-scale magnetic field in the convective zone regions wherever the angular velocity has the strong radial gradient. The direction of the drift depends on the sign of helicity. Thus, the given pumping effect works in the same direction as the propagation of the dynamo wave that is govern by the Parker-Yoshimura rule. The analytic calculations are done within the mean-field magnetohydrodynamic framework using the minimal $\tau$-approximation. We estimate the magnitude of the drift velocity and found that it can be several m/s near the base of the solar convection zone. The implications of the given effect to the solar dynamo are illustrated on the base of the mean-field axisymmetric dynamo model with subsurface shear layer. We found that the helicity-vorticity pumping effect can influence on the features of the sunspot time-latitude diagram, producing the fast drift of the sunspot activity maximum at the rise phase of the cycle and the slow drift at the decay phase of the cycle.

View original: http://arxiv.org/abs/1205.4835