A comparison of spectral and finite-difference simulations of a growing baroclinic wave

✍ Scribed by A. J. Simmons; B. J. Hoskins

• Publisher: John Wiley and Sons
• Year: 1975
• Tongue: English
• Weight: 916 KB
• Volume: 101
• Category: Article
• ISSN: 0035-9009
• DOI: 10.1002/qj.49710142912

✦ Synopsis

Abstract

A comparison is made of integrations of the primitive equations on the sphere using a second‐order finite‐difference model, and spectral models with both triangular and rhomboidal truncation. The initial conditions comprise a baroclinically unstable mid‐latitude jet, and a perturbation of small amplitude. Increasing the resolution in each model gives a good estimate of the exact solution, and thus of the errors involved in each integration.

No one method has a superiority in all respects. Spectral integrations with truncations at zonal wave‐number 16 give a more accurate description of amplitudes and phases in the growing wave than does a finite‐difference integration using a 5° × 3° grid, but a much poorer description of the fronts that form as the disturbance approaches maturity. Large‐scale changes to the zonal‐mean state are predicted to greater accuracy using the spectral models, but smaller‐scale changes are resolved better by the finite‐difference model. The spectral models require less computing time, and less storage. For these experiments, rhomboidal truncation is favoured.