Study of tree-atmosphere interaction and assessment of air quality in real city neighbourhoods

This paper is devoted to the study of the aerodynamic effects of trees on airflow and pollutant dispersion in urban street canyons. The dispersion of traffic-released pollutants in street canyons lined with trees is analysed by means of both wind tunnel experiments and Computational Fluid Dynamics simulations. Different tree planting and street canyon configurations are considered with a focus on the variation in the tree stand density and their implications on pollutant concentrations for several wind directions and aspect ratios. The concepts discussed in the paper can also be applied in practice. For example, we employ a similar methodology to investigate a complex urban site in Bari (Italy) where situations with and without trees are examined and numerical results are compared to field monitored data. The analysis of the results shows the crucial role of trees in dispersion modelling of urban areas.