The use of CFD and mesoscale air quality modelling systemsfor urban applications: Madrid case study

摘要

The air quality in urban areas is of great concern due to the increasingnumber of vehicles in modern cities and also because the city pop-ulation is constantly increasing. The need of having reliable, robustand efficient tools to evaluate the impact of different traffic policies inair quality concentrations has attracted the attention of the scientificcommunity in the last decade. In this contribution we show the resultsof different scenarios produced by different models which constitute acomplete urban air quality management tool. We have used a cellularautomata model CAMO (UPM, Spain) to produce traffic flow withhigh spatial and temporal resolution. The model has been applied overa 1 km x 1 km spatial grid cell in Madrid (Spain) city. CAMO modelproduces traffic flow which is used to generate emission data as inputfor a CFD model, MIMO (Ehrhard et al., 2000). MIMO also receivesboundary and initial conditions from the MM5 mesoscale meteoro-logical model (NCAR/PSU, USA) and the CMAQ air quality mod-elling system (EPA, USA). The CAMO-MIMO-MM5 modelis validated by comparing the results with the values measured in anin-site air quality monitoring station. We have carried out severalexperiments with different scenarios based on the CORINE mobileemission factors and the different mobile subclasses. The systemallows to identify 'hot spots' in the urban canopy with a very highspatial and temporal resolution. We run the model with 5 m spatialresolution and 10 vertical layers up to 50 m. The model simulates thenonlinear effects on street level air quality concentrations which helpsair quality city authorities to take actions according to the expectedresults. Reduction in 30% of the total cars and increase of up to 15%in the public buses (EURO–IV) show important improvements in airquality concentrations.