The University of Illinois, Urbana-Champaign three-dimensional stratosphere-troposphere general circulation model with interactive ozone photochemistry: Fifteen-year control run climatology

A new University of Illinois at Urbana-Champaign 24-layer troposphere-strat osphere general circulation model with interactive photochemistry is presen ted. We document here the results of a 15-year-long control run of the mode l and an evaluation of its performance. The ability of the model to simulat e the Northern Hemisphere polar vortex has been improved because of the mod ification of the gravity wave drag parameterization. The extension and upda te of the chemical routine improved the simulated species distributions. As a result, the agreement of the simulated fields with observations is withi n 20% for total ozone and other species, 5 K for temperature, and 10 m s(-1 ) for zonal wind over most of the atmosphere. The model simulates well the appearance of polar stratospheric clouds and the "ozone hole" over Antarcti ca. However, in some particular points the model results are unrealistic. T hese are (1) a cold bias (similar to 25 K) in the Southern Hemisphere lower stratosphere during austral summer, (2) a warm bias (similar to 20 K) in t he middle stratosphere during austral winter, (3) a warm bias (similar to 1 0 K) near the stratopause in the tropics, and (4) a persistent cold bias of up to 8 K in the lowermost stratosphere almost everywhere over the globe. These problems may be due to the lack of a nonorographic gravity wave drag parameterization in the model, the influence of the top boundary conditions , and/or some problems with model treatment of the zonal wind-planetary wav e interaction in the stratosphere. Despite these few shortcomings, the mode l is now ready to be applied to several climate-chemistry issues such as fu ture ozone layer changes due to increasing greenhouse gas concentrations, t he atmospheric influence of volcanic eruptions, and sun-climate relations.