Evaluation of the RIO-IFDM-street canyon model chain

Integration of all relevant spatial scales in concentration modeling is important for assessing the European limit values for NO2. The local NO2-concentrations are influenced by the regional background, the local emissions and the street canyon effects. Therefore, it is important to consistently combine all these contributions in the model setup which is used for such an assessment. In this paper, we present the results of an integrated model chain, consisting of an advanced measurement interpolation model, a bi-Gaussian plume model and a canyon model to simulate the street-level concentrations over the city of Antwerp, Belgium. The results of this model chain are evaluated against independent weekly averaged NO2 measurements at 49 locations in the city of Antwerp, during both a late autumn and a late spring week. It is shown that the model performed well, explaining between 62% and 87% of the spatial variance, with a RMSE between 5 and 6 μg m−1 and small biases. In addition to this overall validation, the performance of different components in the model chain is shown, in order to provide information on the importance of the different constituents.