A Numerical Study on Estimation of the Trees’ Effects on the Distributions of Fine Particles (PM2.5) in an Urban area

In this study, we investigated the effects of trees planted in an urban area on PM_2.5 reduction using a computational fluid dynamics (CFD) model. For realistic numerical simulations, the Local Data Assimilation and Prediction System (LDAPS) operated by the Korea Meteorological Administration was used to provide the initial and boundary conditions to the CFD model. The CFD model was validated against the PM_2.5 concentrations measured by the sensor networks in the area. We conducted the numerical simulations for three configurations of the trees: 1) no tree (NT) case, 2) a case considering only trees’ drag effect (TD), and 3) a case considering trees’ drag and dry deposition effects (DD). Comparison of the average concentrations showed that the trees in the area reduced the PM_2.5 concentrations during the simulation period. The results showed that trees’ dry deposition can offset the concentration increase caused by trees’ drag effect and, resultantly reduce the PM_2.5 concentrations in the tree-plated area.