Stochastic subgrid modelling for atmospheric large eddy simulations

Abstract

Dynamical subgrid scale parameterizations of stochastic backscatter and eddy dissipation have been calculated for typical atmospheric turbulent flows on the sphere. A methodology based on a stochastic model representation of the subgrid scale eddies in direct numerical simulations, and with wide applicability to fluid flows, has been employed. Large eddy simulations incorporating these subgrid scale parameterizations are found to have energy spectra that compare closely with the results of higher resolution direct numerical simulations for both barotropic and baroclinic turbulent flows. References O'Kane, T.J. and J.S. Frederiksen, Statistical dynamical subgrid-scale parameterizations for geophysical flows, Physica Scripta , 78 , 2008, in press. Frederiksen, J.S., Subgrid-scale parameterizations of eddy-topographic force, eddy viscosity, and stochastic backscatter for flow over topography, J. Atmos. Sci. 56 , 1999, 1481--1494. 2.0.CO;2>doi:10.1175/1520-0469(1999)056 2.0.CO;2 Frederiksen, J.S., and A.G. Davies, Eddy viscosity and stochastic backscatter parameterizations on the sphere for atmospheric circulation models, J. Atmos. Sci. , 54 , 1997, 2475--2492. 2.0.CO;2>doi:10.1175/1520-0469(1997)054 2.0.CO;2 Frederiksen, J.S. and S.M. Kepert, Dynamical subgrid-scale parameterizations from direct numerical simulations, J. Atmos. Sci. , 63 , 2006, 3006--3019. doi:10.1175/JAS3795.1 Frederiksen, J.S. and M.R. Dix and A.G. Davies, The effects of closure-based eddy diffusion on the climate and spectra of a GCM, Tellus A , 55 , 2003, 31--44. doi:10.1034/j.1600-0870.2003.201329.x