Advantages of Spatial Averaging in Semi-implicit Semi-Lagrangian Schemes
Open Access
- 1 January 1992
- journal article
- Published by American Meteorological Society in Monthly Weather Review
- Vol. 120 (1) , 113-123
- https://doi.org/10.1175/1520-0493(1992)120<0113:aosais>2.0.co;2
Abstract
A modified semi-Lagrangian scheme is proposed in the context of semi-implicit forecast models to reduce the important distortion of topographically forced waves that is produced when the Courant–Friedrichs–Lewy (CFL) number is greater than 1. The improved semi-Lagrangian scheme combines the original semi-implicit formulation and the spatial averaging of all nonlinear terms. The impact of the spatial averaging is assessed in two baroclinic forecast models: a global spectral model and a regional gridpoint model. The modified semi-implicit semi-Lagrangian scheme is shown to improve short- and medium-range forecasts, and to increase the efficiency of the models by reducing the number of interpolations by 20%–40%.Keywords
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