1Laboratoire d'Aérologie, UMR5560, CNRS and Université de Toulouse, Toulouse, France
2Met Office, Atmospheric Dispersion Group, Exeter, UK
3FZ Jülich, Institute for Chemistry and Dynamics of the Geosphere – 2: Troposphere, Jülich, Germany
4Max Planck Institute for Meteorology, Hamburg, Germany
5Royal Netherlands Meteorological Institute (KNMI), De Bilt, The Netherlands
6European Centre for Medium-Range Weather Forecasts (ECMWF), Reading, UK
7Deutscher Wetterdienst (DWD), Observatorium Hohenpeißenberg, Germany
8Laboratory of Atmospheric Physics, Aristotle University of Thessaloniki, Thessaloniki, Greece
9Météo-France, Centre National de Recherches Météorologiques, Toulouse, France
10TNO Built Environment and Geosciences, Department of Air Quality and Climate, Utrecht, The Netherlands
11Laboratory of Climatology and Atmospheric Environment, Faculty of Geology and Geoenvironment, University of Athens, Greece
12Atmospheric Environment Division, Biomedical Research Foundation of the Academy of Athens, Greece
Received: 14 Jul 2009 – Discussion started: 07 Aug 2009
Abstract. Three global Chemistry Transport Models – MOZART, MOCAGE, and TM5 – as well as MOZART coupled to the IFS meteorological model including assimilation of ozone (O3) and carbon monoxide (CO) satellite column retrievals, have been compared to surface measurements and MOZAIC vertical profiles in the troposphere over Western/Central Europe for summer 2003. The models reproduce the meteorological features and enhancement of pollution during the period 2–14 August, but not fully the ozone and CO mixing ratios measured during that episode. Modified normalised mean biases are around −25% (except ~5% for MOCAGE) in the case of ozone and from −80% to −30% for CO in the boundary layer above Frankfurt. The coupling and assimilation of CO columns from MOPITT overcomes some of the deficiencies in the treatment of transport, chemistry and emissions in MOZART, reducing the negative biases to around 20%. The high reactivity and small dry deposition velocities in MOCAGE seem to be responsible for the overestimation of O3 in this model. Results from sensitivity simulations indicate that an increase of the horizontal resolution to around 1°×1° and potential uncertainties in European anthropogenic emissions or in long-range transport of pollution cannot completely account for the underestimation of CO and O3 found for most models. A process-oriented TM5 sensitivity simulation where soil wetness was reduced results in a decrease in dry deposition fluxes and a subsequent ozone increase larger than the ozone changes due to the previous sensitivity runs. However this latest simulation still underestimates ozone during the heat wave and overestimates it outside that period. Most probably, a combination of the mentioned factors together with underrepresented biogenic emissions in the models, uncertainties in the modelling of vertical/horizontal transport processes in the proximity of the boundary layer as well as limitations of the chemistry schemes are responsible for the underestimation of ozone (overestimation in the case of MOCAGE) and CO found in the models during this extreme pollution event.
Revised: 04 Jan 2010 – Accepted: 06 Jan 2010 – Published: 26 Jan 2010
Ordóñez, C., Elguindi, N., Stein, O., Huijnen, V., Flemming, J., Inness, A., Flentje, H., Katragkou, E., Moinat, P., Peuch, V.-H., Segers, A., Thouret, V., Athier, G., van Weele, M., Zerefos, C. S., Cammas, J.-P., and Schultz, M. G.: Global model simulations of air pollution during the 2003 European heat wave, Atmos. Chem. Phys., 10, 789-815, doi:10.5194/acp-10-789-2010, 2010.