Atmos. Chem. Phys. Discuss., 9, 16853-16911, 2009
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Global model simulations of air pollution during the 2003 European heat wave
C. Ordóñez1,2, N. Elguindi1, O. Stein3,4, V. Huijnen5, J. Flemming6, A. Inness6, H. Flentje7, E. Katragkou8, P. Moinat9, V.-H. Peuch9, A. Segers5,10, V. Thouret1, G. Athier1, M. van Weele5, C. S. Zerefos11, J.-P. Cammas1, and M. G. Schultz3
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, Faculty of Geology, University of Athens, Athens, Greece

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 Europe for summer 2003. The models reproduce the meteorological features and enhancement of pollution in the troposphere over Central and Western Europe 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% in the case of 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%. Results from sensitivity simulations indicate that an increase of the coarse resolution of the global models 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 global 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 those of other sensitivity runs where the horizontal resolution or European emissions are increased. 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 and CO found in most of the models during this extreme pollution event.

Citation: 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. Discuss., 9, 16853-16911, doi:10.5194/acpd-9-16853-2009, 2009.
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