Effects of Gravity Wave Drag in the Berlin Troposphere-Stratosphere-Mesosphere GCM
The effects of including various, generally quite simple, representations of gravity wave drag on the evolution of the circulation of the middle atmosphere of the troposphere- stratosphere-mesosphere general circulation model developed at the Free University of Berlin is investigated. Specifically, the importance of gravity wave drag for the development of stratospheric sudden warmings in the model simulations are discussed. It is shown that changing the form of the drag in the mesosphere of the model is unimportant for the development of the circulation below the upper stratosphere over periods of about 20 days. This is despite the important effects of the mesospheric drag on the climatological state of the model. Topographic gravity wave drag acting in the lower stratosphere can significantly affect the development of sudden warmings via direct effects on the local flow and the planetary wave stuctures in the stratosphere and troposphere.
KeywordsGeneral Circulation Model Planetary Wave Lower Stratosphere Numerical Weather Prediction Model Stratospheric Warming
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