Abstract

The solar convection zone has provided many challenges for the theoretical modeling of dynamics within our nearest star. The tachocline, a region of strong shear near the base of the convection zone, has received much attention due to its likely role in the generation of the global-scale magnetic... Show moreThe solar convection zone has provided many challenges for the theoretical modeling of dynamics within our nearest star. The tachocline, a region of strong shear near the base of the convection zone, has received much attention due to its likely role in the generation of the global-scale magnetic fields. The establishment and maintenance of the solar tachocline has been variously attributed to angular momentum transport via gravity waves, magnetic torques and anisotropic mixing processes. Self consistently capturing the turbulent dynamics of the convection zone and underlying radiative zone through 3-D numerical modeling is difficult due to the wide range of scales involved. Prior simulations using the 3-D anelastic spherical harmonic (ASH) code of convection in a full spherical shell admitting penetration into a stable region below have yielded differential rotation profiles whose latitudinal contrast is considerably smaller than in simulations without penetration. We believe that the relatively soft stabilizing entropy gradients in the overshooting regions may have resulted in unusually strong circulations that worked against the Reynolds stresses, thus diminishing the differential rotation. Here we turn to ASH simulations with more realistic stiffer entropy gradients and reduced diffusivities in the radiative zone. We report on the balances achieved within the region of penetration that allows the convection zone to return to differential rotation profiles in closer accord with helioseismic deductions, including possessing a tachocline of shear. Show less