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Paper: Fighting the Taylor-Proudman Constraint - How to Get Differential Rotation Solar-like?
Volume: 346, Large-scale Structures and their Role in Solar Activity
Page: 75
Authors: Rempel, M.
Abstract: We present a model for the solar differential rotation and meridional circulation based on a mean-field parametrization of the Reynolds-stresses that drive the differential rotation. We include the subadiabatic part of the tachocline and show that this, in conjunction with turbulent heat conductivity within the convection zone and upper overshoot region, provides the key physics to break the Taylor-Proudman constraint, which dictates normally differential rotation with contour lines parallel to the axis of rotation. We show that solar-like differential rotation with contour lines almost aligned with the radial direction is a very robust result of the model, which does not depend on the details of the Reynolds-stress and the assumed viscosity, as long as the Reynolds-stress transports angular momentum towards the equator. The meridional flow is more sensitive to the details of the assumed Reynolds-stress, but a one-cell flow, equatorward at the base of the convection zone and poleward in the upper half of the convection zone, is the preferred flow pattern for a variety of different assumptions concerning the Reynolds-stress. Incorporating the feedback of a toroidal magnetic field through Lorentz force into this model allows us to estimate up to which field strength meridional flow can transport toroidal magnetic field at the base of the convection zone equatorward. We find an upper limit of 2 to 3 T (20 to 30 kG) in our investigation.
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