Nonkinematic solar dynamo models with double-cell meridional circulation

TL;DR

This paper develops a comprehensive nonlinear solar dynamo model incorporating detailed physical effects and double-cell meridional circulation, revealing how magnetic feedback influences the solar magnetic cycle and its long-term variability.

Contribution

It introduces a dynamically consistent nonlinear dynamo model with detailed physics and investigates the impact of magnetic feedback on solar cycle properties and variability.

Findings

Magnetic cycle period decreases with increasing cycle magnitude.

Long-term magnetic variations are excited by hemispheric magnetic helicity exchange.

Magnetic feedback alters differential rotation and meridional circulation patterns.

Abstract

Employing the standard solar interior model as input we construct a dynamically-consistent nonlinear dynamo model that takes into account the detailed description of the \Lambda- effect, turbulent pumping, magnetic helicity balance, and magnetic feedback on the differential rotation and meridional circulation. The background mean-field hydrodynamic model of the solar convection zone accounts the solar-like angular velocity profile and the double-cell meridional circulation. We investigate an impact of the nonlinear magnetic field generation effects on the long-term variability and properties of the magnetic cycle. The nonlinear dynamo solutions are studied in the wide interval of the \alpha effect parameter from a slightly subcritical to supercritical values. It is found that the magnetic cycle period decreases with the increasing cycle's magnitude. The periodic long-term variations of the magnetic cycle are excited in case of the overcritical \alpha effect. These variations result from the hemispheric magnetic helicity exchange. It depends on the magnetic diffusivity parameter and the magnetic helicity production rate. The large-scale magnetic activity modifies the distribution of the differential rotation and meridional circulation inside convection zone. It is found that the magnetic feedback on the global flow affects the properties of the long-term magnetic cycles. We confront our findings with solar and stellar magnetic activity observations.