1Centre for Research in Earth and Space Science, Atmospheric Modelling and Data Assimilation Laboratory, York University, Toronto, Canada
2Institute of Environmental Engineering Systems, Warsaw University of Technology, Warsaw, Poland
3Science and Technology Branch, Environment Canada, Toronto, Canada
4Science and Technology Branch, Environment Canada, Montréal, Canada
5Smithsonian Astrophysical Observatory, Cambridge, MA, USA
6Institute of Environmental Physics, University of Bremen, Germany
*now at: Goddard Earth Sciences and Technology, University of Maryland Baltimore County, Baltimore, MD, USA
Abstract. Tropospheric chemistry and air quality processes were implemented on-line in the Global Environmental Multiscale model. The integrated model, GEM-AQ, has been developed as a platform to investigate chemical weather at scales from global to urban. The model was exercised for five years (2001–2005) to evaluate its ability to simulate seasonal variations and regional distributions of trace gases such as ozone, nitrogen dioxide and carbon monoxide on the global scale. The model results presented are compared with observations from satellites, aircraft measurement campaigns and balloon sondes.