A numerical model with an averaging volume sufficiently small that the eddies contained entirely within it (i.e., the unresolved eddies) are of inertial-range scales and smaller. The larger energy-containing eddies are resolved explicitly away from the boundaries. In the boundary layer the energy-containing eddies are not resolved near the surface and near the inversion at the top. In these regions a subgrid-scale parameterization is needed.