1Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR7583, CNRS/INSU – Université Paris Est Créteil (UPEC) et Université Paris Diderot (UPD), France
2Laboratoire d'Aérologie, UMR5560, CNRS and Université de Toulouse, Toulouse, France
3Institute of Atmospheric Sciences and Climate, CNR, Bologna, Italy
4Rhenish Institute for Environmental Research at the University of Cologne, Köln, Germany
5European Centre for Medium range Weather Forecasting, Reading, UK
6INERIS, Institut National de l'Environnement Industriel et des Risques, Parc techn. ALATA, Verneuil-en Halatte, France
7Laboratoire de Météorologie Dynamique, IPSL, Ecole Polytechnique, Palaiseau, France
8Météo-France, Centre National de Recherche Météorologique, Toulouse, France
9Laboratory of Atmospheric Physics, Aristotle University of Thessaloniki, Greece
10FZ Jülich, Institute for chemistry and dynamics of the Geoshere-2: Troposphere, Jülich, Germany
11Norwegian Meteorological Institute, Oslo, Norway
12Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Bologna, Italy
Received: 10 Aug 2011 – Discussion started: 26 Oct 2011
Abstract. A detailed 3-D evaluation of an ensemble of five regional Chemistry Transport Models (RCTM) and one global CTM with focus on free tropospheric ozone over Europe is presented. It is performed over a summer period (June to August 2008) in the context of the GEMS-RAQ project. A data set of about 400 vertical ozone profiles from balloon soundings and commercial aircraft at 11 different locations is used for model evaluation, in addition to satellite measurements with the infrared nadir sounder (IASI) showing largest sensitivity to free tropospheric ozone. In the middle troposphere, the four regional models using the same top and boundary conditions from IFS-MOZART exhibit a systematic negative bias with respect to observed profiles of about −20%. Root Mean Square Error (RMSE) values are constantly growing with altitude, from 22% to 32% to 53%, respectively for 0–2 km, 2–8 km and 8–10 km height ranges. Lowest correlation is found in the middle troposphere, with minimum coefficients (R) between 0.2 to 0.45 near 8 km, as compared to 0.7 near the surface and similar values around 10 km. A sensitivity test made with the CHIMERE mode also shows that using hourly instead of monthly chemical boundary conditions generally improves the model skill (i.e. improve RMSE and correlation). Lower tropospheric 0–6 km partial ozone columns derived from IASI show a clear North-South gradient over Europe, which is qualitatively reproduced by the models. Also the temporal variability showing decreasing ozone concentrations in the lower troposphere (0–6 km columns) during summer is well reproduced by models even if systematic bias remains (the value of the bias being also controlled by the type of used boundary conditions). A multi-day case study of a trough with low tropopause was conducted and showed that both IASI and models were able to resolve strong horizontal gradients of middle and upper tropospheric ozone occurring in the vicinity of an upper tropospheric frontal zone.
Revised: 20 Mar 2012 – Accepted: 23 Mar 2012 – Published: 03 Apr 2012
Zyryanov, D., Foret, G., Eremenko, M., Beekmann, M., Cammas, J.-P., D'Isidoro, M., Elbern, H., Flemming, J., Friese, E., Kioutsioutkis, I., Maurizi, A., Melas, D., Meleux, F., Menut, L., Moinat, P., Peuch, V.-H., Poupkou, A., Razinger, M., Schultz, M., Stein, O., Suttie, A. M., Valdebenito, A., Zerefos, C., Dufour, G., Bergametti, G., and Flaud, J.-M.: 3-D evaluation of tropospheric ozone simulations by an ensemble of regional Chemistry Transport Model, Atmos. Chem. Phys., 12, 3219-3240, doi:10.5194/acp-12-3219-2012, 2012.