Tracer Transport by Planetary Waves: A Comparison of Explicit and Parameterized Models

Abstract

A two-dimensional stratospheric tracer transport parameterization is developed using the theory of small amplitude generalized lagrangian means. The parameterization is tested with a severely truncated three-dimensional model for a tracer with a constant tropospheric source and a height dependent stratospheric sink. Results from an explicit three-dimensional calculation of the tracer transport are compared to the results from a two-dimensional version of the model in which eddy fluxes are parameterized using data from the full three-dimensional model. The relative tracer transport by the eulerian, residual and lagrangian velocities is also examined. Two experiments are run: the first experiment has a steady planetary wave superimposed on a climatological zonal mean wind, while the second simulates the large wave-mean flow interaction processes associated with a sudden stratospheric warming. The semilagrangian tracer transport parameterization is valid for steady state conditions and some transient conditions. The parameterization breaks down during a simulated sudden stratospheric warming. Once the parameterization breaks down, the parameterized transport remains unrelated to the actual transport at all subsequent times.