A Further Test of a Scale-Dependent Filter for Use in Finite-Difference Modeling

Abstract

A primitive equation channel model is used to integrate an initial state consisting of a zonally independent unstable jet on which is superimposed a small-amplitude perturbation. The jet possesses both horizontal and vertical shear. The horizontal grid spacing is scaled to 100 km, allowing the amplifying disturbance to form fairly sharp surface frontal zones. Two integrations are made, with and without a scale-dependent filter designed to remove small-scale components. The filter removes the subfrontal-scale ?noise? without changing significantly the larger scale motion.