Table of Contents
ISRN Meteorology
Volume 2012, Article ID 860234, 22 pages
Research Article

Evaluating the Performance of a Regional-Scale Photochemical Modelling System: Part I—Ozone Predictions

Department of Astronomy and Meteorology, Faculty of Physics, University of Barcelona, Avinguda Diagonal 647, 08028 Barcelona, Spain

Received 17 September 2012; Accepted 8 October 2012

Academic Editors: D. Contini, A. Saha, and C. Zerefos

Copyright © 2012 R. Arasa et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We present a detailed evaluation of the seasonal performance of the Community Multiscale Air Quality (CMAQ) modelling system and the PSU/NCAR meteorological model coupled to a new Numerical Emission Model for Air Quality (MNEQA). The combined system simulates air quality at a fine resolution (3 km as horizontal resolution and 1 h as temporal resolution) in north-eastern Spain, where problems of ozone pollution are frequent. An extensive database compiled over two periods, from May to September 2009 and 2010, is used to evaluate meteorological simulations and chemical outputs. Our results indicate that the model accurately reproduces hourly and 1-h and 8-h maximum ozone surface concentrations measured at the air quality stations, as statistical values fall within the EPA and EU recommendations. However, to further improve forecast accuracy, three simple bias-adjustment techniques—mean subtraction (MS), ratio adjustment (RA), and hybrid forecast (HF)—based on 10 days of available comparisons are applied. The results show that the MS technique performed better than RA or HF, although all the bias-adjustment techniques significantly reduce the systematic errors in ozone forecasts.