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

Abstract

A new University of Illinois at Urbana‐Champaign 24‐layer troposphere‐stratosphere general circulation model with interactive photochemistry is presented. We document here the results of a 15‐year‐long control run of the model and an evaluation of its performance. The ability of the model to simulate the Northern Hemisphere polar vortex has been improved because of the modification of the gravity wave drag parameterization. The extension and update of the chemical routine improved the simulated species distributions. As a result, the agreement of the simulated fields with observations is within 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 Antarctica. However, in some particular points the model results are unrealistic. These are (1) a cold bias (∼25 K) in the Southern Hemisphere lower stratosphere during austral summer, (2) a warm bias (∼20 K) in the middle stratosphere during austral winter, (3) a warm bias (∼10 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 wave interaction in the stratosphere. Despite these few shortcomings, the model is now ready to be applied to several climate‐chemistry issues such as future ozone layer changes due to increasing greenhouse gas concentrations, the atmospheric influence of volcanic eruptions, and sun‐climate relations.