Realistic quasi-biennial oscillations in a simulation of the global climate



The tropical quasi-biennial oscillation is one of the most spectacular examples of low frequency variability observed in the Earth's atmosphere, yet the oscillation is noted for its absence from numerical simulations of the global climate. Recent studies suggest that much of the required wave forcing for the oscillation is likely to come from buoyancy (gravity) waves [Sato and Dunkerton, 1997; Dunkerton, 1997] that are not well resolved in the numerical models currently used for climate prediction and global weather forecasting. Here we show that when the effects of these missing waves are parametrized in a comprehensive numerical model of the atmosphere, the simulation of the climate is improved by the generation of a realistic quasi-biennial oscillation in the stratosphere.