Alleviating α quenching by solar wind and meridional flows

Abstract

Aims. We study the ability of magnetic helicity expulsion to alleviate catastrophic α-ωquenching in mean field dynamos in two-dimensional spherical wedge domains. Methods. Motivated by the physical state of the outer regions of the Sun, we consider α2\Ω$ mean field models with a dynamical α quenching. We include two mechanisms which have the potential to facilitate helicity expulsion, namely advection by a mean flow ("solar wind") and meridional circulation. Results. We find that a wind alone can prevent catastrophic quenching, with the field saturating at finite amplitude. In certain parameter ranges, the presence of a large-scale meridional circulation can reinforce this alleviation. However, the saturated field strengths are typically below the equipartition field strength. We discuss possible mechanisms that might increase the saturated field. © 2011 ESO.