Non-Local Transport in Turbulent MHD Convection

The nonlocal, non-diiusive transport of passive scalars in turbulent MHD convection is investigated using tran-silient matrices, which describe the "probability" that a tracer particle beginning at one position in a ow will be advected to another position after some time. We present a new method for calculating these matrices from simulation data which involves following the trajectories of passive tracer particles and calculating their transport statistics. The method is applied to study transport in several simulations of turbulent, rotating, three dimensional, compressible, penetrative MHD convection. Transport coeecients and other useful diagnostics such as moments of the transilient matrix are used to quantify the transport, which is found to resemble advection more closely than diiusion. Some of the results also have direct relevance for other physical problems, such as light element depletion in solar-type stars. In particular the large kurtosis found for downward moving particles at the base of the convection zone implies a relatively large number of extreme events-particles traveling deep into the radiative interior where light elements would be ee-ciently burned.