Solar turbulent dynamo near convective overshoot layer and radiative tachocline

Abstract

In order to extend the abilities of the αΩ-dynamo model to explain the observed regularities and anomalies of the solar magnetic activity, the magnetic quenching of the α-effect were included in the model, and newest helioseismically determined inner rotation of the Sun has been used. Allowance for the radial inhomogeneity of turbulent velocity in derivations of the helicity parameter resulted in a change of sign of the α-effect from positive to negative in the northern hemisphere near the bottom of the solar convection zone (SCZ). The change of sign is very important for direction of Parker’s dynamo-waves propagation and for parity of excited magnetic fields. The period of the dynamo-wave calculated with taking into account the magnetic α-quenching is about seven years, that agrees by order of magnitude with the observed mean duration of the sunspot cycles. Using the modern helioseismology data to define dynamo-parameters, we conclude that north–south asymmetry should exist in the meridional field. The calculated configuration of the net meridional field is likely to explain the magnetic anomaly of polar fields (the apparent magnetic “monopole”) observed near the maxima of solar cycles.