Dynamics of the solar tachocline II: the stratified case

Abstract

We present a detailed numerical study of the Gough & McIntyre model for the solar tachocline. This model explains the uniformity of the rotation profile observed in the bulk of the radiative zone by the presence of a large-scale primordial magnetic field confined below the tachocline by flows originating from within the convection zone. We attribute the failure of previous numerical attempts at reproducing even qualitatively Gough & McIntyre's idea to the use of boundary conditions which inappropriately model the radiative--convective interface. We emphasize the key role of flows downwelling from the convection zone in confining the assumed internal field. We carefully select the range of parameters used in the simulations to guarantee a faithful representation of the hierarchy of expected lengthscales. We then present, for the first time, a fully nonlinear and self-consistent numerical solution of the Gough & McIntyre model which qualitatively satisfies the following set of observational constraints: (i) the quenching of the large-scale differential rotation below the tachocline - including in the polar regions - as seen by helioseismology (ii) the confinement of the large-scale meridional flows to the uppermost layers of the radiative zone as required by observed light element abundances and suggested by helioseismic sound-speed data.

21 pages, 15 figures, submitted to MNRAS

References in corpus (5)

• Global-Scale Turbulent Convection and Magnetic Dynamo Action in the Solar Envelope
• Solar differential rotation and meridional flow: The role of a subadiabatic tachocline for the Taylor-Proudman balance
• Magnetic confinement of the solar tachocline
• On the penetration of meridional circulation below the solar convection zone
• Magnetic field confinement by meridional flow and the solar tachocline

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• Bridging the Rossby number gap in rapidly rotating thermal convection
• Detectability of axisymmetric magnetic fields from the core to the surface of oscillating post-main sequence stars
• On obliquely magnetized and differentially rotating stars