On the compatibility of a flux transport dynamo with a fast tachocline scenario

Karak Bidya Binay, bidya_karak@physics.iisc.ernet.in, Department of Physics, Indian Institute of Science, Bangalore 560012, India
Petrovay Kristof, K.Petrovay@astro.elte.hu, Budapest, Hungary

Abstract
We employ a flux transport dynamo model based on the Surya code coupled with a simple feedback formula relating the thickness of the tachocline to the amplitude of the Maxwell stresses of the dynamo generated magnetic field. The dynamo model is found to be robust against the nonlinearity introduced by this simplified fast tachocline mechanism. Solar-like butterfly diagrams are found to persist and the overall thickness of the tachocline is well within the range admitted by helioseismic constraints. The thickness of the tachocline is found to vary with latitude and time. The latitudinal variation of the tachocline thickness is somewhat in agreement with seismic results. However the cycle related variations are of order ±25%, apparently just slightly outside the bounds admitted by helioseismology. Introducing a further parameter into our feedback formula readily allows further fine tuning of the thickness variations.