Validation of the dispersion model CAR-FMI against measurements near a major road

A field measurement campaign was conducted near a major road in southern Finland from 15 September to 30 October 1995. The concentrations of NO, NO2 and O-3 were measured simultaneously at three locations, at three heights (3.5, 6 and 10 m) on both sides of the road. The relevant meteorological parameters and traffic densities were also measured on site. We have compared measured concentration data with the predictions from the road network dispersion model CAR-FMI, used in combination with a meteorological preprocessing model. According to statistical analyses used, the overall agreement of the model predictions and measured data was reasonably good. For all data (N = 587), the modelling system overpredicts NOx concentrations with a fractional bias FB = +0.13 and O-3 concentrations with FB = +0.08, while for NO2 concentrations FB = -0.02. The experimental dataset is available for the evaluation of other roadside dispersion models.