Horizontal Reynolds Stress and Radial Rotation Law of the Sun

Abstract

Experiments with the design of the mean-field models for the differential solar rotation are reported, in which the rotational influence on the turbulence/convection is parametrizised in the sense of a series expansion of the Coriolis parameter Ω*. The possibility of using only the one well-known free turbulence parameter is excluded by both observational and theoretical reasons. In particular, the observation of a positive horizontal Reynolds stress, <u′ _θ u′ _Φ > cosθ≥0, requires the introduction of additional terms, the number of which, in the next order, is four. While the parameters can be completely specified with the surface-dominated observations, the computational result is the inner rotation law. The models prove to have difficulties with the angular velocity along the rotation axis if, indeed, the horizontal Reynolds stress is adopted to be positive. In this case those smooth radial laws which are in accordance with the recent helioseismological results are not easy to produce.