The effects of Rossby wave mixing are parameterized by externally specified coefficients, K yy , which are used consistently in the zonal mean momentum equation and the diffusion term of the tracer transport equation. Rossby wave mixing is reduced in the tropics. Transport between the tropics and midlatitudes is controlled by advection in the model. In the annual mean, the flow of air is directed from the tropics towards midlatitudes. However, advection between tropics and midlatitudes takes place in both directions at stratospheric altitudes at any given time.
Calculated temperatures show some discrepancies with observations in the polar regions.
Tropical and mid latitude profiles calculated by the model are in reasonable agreement with observations.