Atmospheric Chemistry and Physics www.atmos-chem-phys.net 1680-7316 1680-7324 5 1 2005 10.5194/acp-5-169-2005 http://www.atmos-chem-phys.net/5/169/2005/ http://www.atmos-chem-phys.net/5/169/2005/acp-5-169-2005.html http://www.atmos-chem-phys.net/5/169/2005/acp-5-169-2005.pdf 169 190 2005-01-24 Comparison and evaluation of modelled and GOME measurement derived tropospheric NO₂ columns over Western and Eastern Europe I. B. Konovalov M. Beekmann R. Vautard J. P. Burrows A. Richter H. Nüß N. Elansky Institute of Applied Physics, Russian Academy of Sciences, Nizhniy Novgorod, Russia Service d’Aéronomie, Institut Pierre Simon Laplace, Paris, France Laboratoire de Météorologie Dynamique, Institut Pierre Simon Laplace, Paris, France Institute of Environmental Physics and Remote Sensing, IUP/IFE, University of Bremen, Bremen, Germany Institute of Atmospheric Physics, Russian Academy of Sciences, Moscow, Russia We present the results of a first comparison of the tropospheric NO₂ column amounts derived from the measurements of the Global Ozone Monitoring Experiment (GOME) with the simulated data from a European scale chemistry transport model (CTM) which is distinct from existing global scale CTMs in higher horizontal resolution and more detailed description of the boundary layer processes and emissions. We employ, on the one hand, the newly developed extended version of the CHIMERE CTM, which covers both Western and Eastern Europe, and, on the other hand, the most recent version (Version 2) of GOME measurement based data-products, developed at the University of Bremen. We evaluate our model with the data from ground based monitoring of ozone and verify that it has a sufficiently high level of performance, which is expected for a state-of-the-art continental scale CTM. The major focus of the study is on a systematic statistical analysis and a comparison of spatial variability of the tropospheric NO₂ columns simulated with CHIMERE and derived from GOME measurements. The analysis is performed separately for Western and Eastern Europe using the data for summer months of 1997 and 2001. In this way, we obtain useful information on the nature and magnitudes of uncertainties of spatial distributions of the considered data. Specifically, for Western Europe, it is found that the uncertainties of NO₂ columns from GOME and CHIMERE are predominantly of the multiplicative character, and that the mean relative random (multiplicative) errors of the GOME measurement derived and simulated data averaged over the summer seasons considered do not exceed 23% and 32%, respectively. The mean absolute (additive) errors of both kinds of the data are estimated to be less than 3x10¹⁴mol/cm². In Eastern Europe, the uncertainties have more complex character, and the separation between their multiplicative and additive parts is not sufficiently unambiguous. It is found, however, that the total random errors of NO₂ columns from both GOME and CHIMERE over Eastern Europe are not, on the average, larger than the errors of the NO₂ columns with similar magnitudes over Western Europe.