A hybrid mesoscale-gaussian plume approach to air pollution analysis in heterogeneous regions

Two Gaussian Plume Models (GPM) such as CALINE4 and HIWAY2 models have been extensively used in assessing the impacts of existing and proposed sources of air pollution on local and urban air quality, particularly for regulatory applications for non-reactive pollutants. These models require the input of the basic meteorological data: wind speed, wind direction, mixing height and stability class besides the geometry of the line sources and the receptors and the emission data.

However, these models are limited by assuming homogeneity. Various climatic zones display significant heterogeneity particularly along the coasts and urban regions. To introduce these mesoscale effects a hybrid mesoscale Gaussian Plume approach is presented. Accordingly, a mesoscale model is used to simulate thermodynamic and wind fields for the GPM. For this purpose, ARPS (Advanced Regional Prediction Systems), a non-hydrostatic, compressible model designed for storm and mesoscale atmospheric simulation and real-time numerical weather prediction is applied. The model helps in providing surrogate data which is difficult to obtain in the temporal and spatial scales that the diffusion model requires. Effect of land-use change and local circulation such as sea breezes are also better represented.

Results are compared to simulated outputs from Hysplit (Hybrid Single-Particle Lagrangian Integrated Trajectory) model. The trajectory and dispersion as well as relative concentration estimation of air pollutants will be presented for heterogeneous climatic zones.