A Study of Trajectory Uncentering in Semi-Lagrangian Models

Abstract

Application of trajectory uncentering is an effective remedy for ensuring noise-free solutions in semi-implicit semi-Lagrangian (SISL) models. In this study we have employed a one-dimensional SISL linear shallow-water model to investigate the impact of second-order trajectory uncentering on the meteorologically significant Rossby wave solutions. This study is an extension of the results reported in Semazzi and Dekker (1994) where first-order semi-Lagrangian trajectory uncentering was investigated. We show that for typical resolutions, in this case Δx=O(100 km) and Δt<1 hr, application of first-order uncentering results in large truncation errors for planetary-scale waves of the atmosphere. Our main result is that application of second-order uncentering drastically reduces these truncation errors.