The anisotropy of local turbulence in the Earth's core

The anisotropy of local turbulence in the Earth's core is examined. It is r ecognized that small-scale motions in the core are strongly influenced by t he Earth's rotation and its magnetic field. A small region of the core is s imulated (the computational box), across which the prevailing large-scale ( toroidal) magnetic field is supposed to be uniform and in which the tempera ture or compositional gradient providing the buoyancy that powers the turbu lence is parallel to the (uniform) gravitational field. The simulations are used to estimate the turbulent fluxes of mean fields and their dependence on the latitude at which the computational box is situated. It is found tha t the effect of local turbulence on the diffusion of large-scale fields is significant, and that turbulent transport is anisotropic. It is believed th at the results of the present study will prove useful in determining geophy sically realistic diffusivities for use in future global geodynamo simulati ons.