Realistic Quasi-Biennial Oscillations in a simulation of the global climate

The tropical quasi-biennial oscillation is one of the most spectacular exam ples of low frequency variability observed in the Earth's atmosphere, yet t he oscillation is noted for its absence from numerical simulations of the g lobal climate. Recent studies suggest that much of the required wave forcin g for the oscillation is likely to come from buoyancy (gravity) waves [Sato and Dunkerton, 1997; Dunkerton, 1997] that are not well resolved in the nu merical models currently used for climate prediction and global weather for ecasting. Here we show that when the effects of these missing waves are par ametrized in a comprehensive numerical model of the atmosphere, the simulat ion of the climate is improved by the generation of a realistic quasibienni al oscillation in the stratosphere.