Evaluation of a Year-Long Ozone Hindcast for 2006 as Part of a DEFRA Model Intercomparison

A variant of the operational forecast configuration of the Met Office's newly developed Eulerian Air Quality Forecast Model was used to generate an air quality hindcast for 2006 as part of a DEFRA model intercomparison. Verification of predicted ozone concentrations was carried out by comparing against hourly observations from 15 rural and urban background sites spread over the UK. Models were primarily assessed statistically using standard metrics including bias, mean error, correlation, and fraction of predictions within a factor of 2 of observations for (a) all observations, and (b) periods of elevated ozone (>100 mu g/m(3)). We will present results showing that the Met Office model is competitive with other models for hourly ozone, but is best in class at modelling episodes of elevated ozone. The results indicate that the availability of high qualitymet data and interactive treatment of chemistry and meteorology are both important in modelling ozone episodes.