The quasi-geostrophic advective wave in a baroclinic zonal current

✍ Scribed by R. C. Sutcliffe

• Book ID: 104570812
• Publisher: John Wiley and Sons
• Year: 1951
• Tongue: English
• Weight: 446 KB
• Volume: 77
• Category: Article
• ISSN: 0035-9009
• DOI: 10.1002/qj.49707733207

✦ Synopsis

Abstract

An idealised advective wave is studied on the assumption of geostrophic advection of temperature. There is a genuine instability of zonal motion due to this factor and the wave form is similar to thermally asymmetrical depressions and anticyclones. The speed of the unstable waves is Ū − U~c~/2 rather than the Ū − U~c~ of barotropic theory (Ū the mean zonal wind, U~c~ the Rossby westward component due to variation of Coriolis parameter).

Waves become stable when (approximately) the root‐mean‐square zonal thermal wind becomes equal to U~c~. This is near the stationary wave length. There are two types of stable waves, the thermally in‐phase and the thermally antiphase waves. The antiphase waves move eastward relative to the surface zonal flow, the in‐phase waves are retrograde.

The wave characteristics depend on the thermal‐wind conditions, the surface zonal wind is simply additive to the wave speed.

The results support the author's development theory. They do not encourage much optimism in the direct application of barotropic concepts to the baroclinic atmosphere.