Forecasting air quality in the Greater Athens area for the year 2004: an intercomparison of the results of four different dispersion models

Forecasts for the NO,concentration levels in the Greater Athens area in 200 4 are compared to the corresponding figures for 1990. Simulations are perfo rmed for two meteorological cases using four different dispersion models. T wo different emission inventories are employed in the simulations. The firs t is based on the conditions for the year 1990, while the second is the ref erence scenario for the year 2004, taking into account all major public wor ks under construction. In order to ensure the validity of the individual mo dels, simulation results are compared with available measurements for the y ear 1990. All models show an overprediction of the maximum NO,concentration s, but in general the simulation results show satisfactory agreement with t he observations. Excellent agreement is found between the results of all mo dels with regard to the distribution of the 50 maximum hourly NOx concentra tions. Reductions of the peak NOx levels of order of 35% are forecast by al l models between 1990 and the reference scenario for 2004.