Resonance in Forced Flux Transport Dynamos

Abstract

We show that simple 2 and 3-layer flux-transport dynamos, when forced at the top by a poloidal source term, can produce a widely varying amplitude of toroidal field at the bottom, depending on how close the meridional flow speed of the bottom layer is to the propagation speed of the forcing applied above the top layer, and how close the amplitude of the $\alpha$-effect is to two values that give rise to a resonant response. This effect should be present in this class of dynamo model no matter how many layers are included. This result could have implications for the prediction of future solar cycles from the surface magnetic fields of prior cycles. It could be looked for in flux-transport dynamos that are more realistic for the Sun, done in spherical geometry with differential rotation, meridional flow and $\alpha$-effect that vary with latitude and time as well as radius. Because of these variations, if resonance occurs, it should be more localized in time, latitude and radius.

Accepted in ApJ

References in corpus (3)

• Solar Meridional Circulation from Doppler Shifts of the Fe I line at lambda 5250 Angstroms as Measured by the 150-foot Solar Tower Telescope at the Mt. Wilson Observatory
• Observation and Modeling of the Solar-Cycle Variation of the Meridional Flow
• Coexisting stochastic and coherence resonance in a mean-field dynamo model for Earth's magnetic field reversals

Cited by in corpus (4)

• Variations of the solar cycle profile in a solar dynamo with fluctuating dynamo governing parameters
• Parity fluctuations in stellar dynamos
• Resonances for activity waves in spherical mean field dynamos
• Parametric Modulation of Dynamo Waves