The Effect of Orographically Excited Gravity Wave Drag on the General Circulation of the Lower Stratosphere and Troposphere

Abstract The influence of large-scale momentum sinks, due to breaking of orographically excited gravity waves, on the Northern Hemisphere wintertime circulation of the troposphere and lower stratosphere is examined by introducing a simple wave drag parameterization into the Canadian Climate Centre general circulation model (GCM). Results from GCM climate simulations are presented to show that the large-scale momentum sinks resulting from breaking gravity waves play an important role in determining the structure of the large-scale flow in the troposphere and lower stratosphere. It is argued that these results provide convincing evidence of the importance which must be attached to representing such wave drag effects in models designed for numerical weather prediction and general circulation studies.