Differential rotation and meridional flow in the solar convection zone and beneath

Abstract

The influence of the basic rotation on anisotropic and inhomogeneous turbulence is discussed in the context of differential rotation theory. An improved representation for the original turbulence leads to a $\Lam$-effect which complies with the results of 3D numerical simulations. The resulting rotation law and meridional flow agree well with both the surface observations ($\partial\Om/\partial r<0$ and meridional flow towards the poles) and with the findings of helioseismology. The computed equatorward flow at the bottom of convection zone has an amplitude of about 10 m/s and may be significant for the solar dynamo. The depth of the meridional flow penetration into the radiative zone is proportional to $\nu^{0.5}_\mathrm{core}$, where $\nu_\mathrm{core}$ is the viscosity beneath the convection zone. The penetration is very small if the tachocline is laminar.