High-latitude filtering in global grid-point models.

Abstract

Latitude-longitude grid-point models with explicit time schemes require filtering of unstable short waves at high latitudes to avoid the use of prohibitive short time steps. Using a shallow water model and a Rossby-Haurwitz wave as an initial condition, an examination of the effect of several filtering procedures on the numerical solution is performed. It is found that ad hoc filtering techniques can cause spurious energy and momentum transfers to occur which ultimately affect the solution at all latitudes.-from Authors