Understanding air pollutant dispersion in a Dutch neighborhood using DALES

Abstract

This study investigates pollutant dispersion from residential wood burning in a neighborhood in Utrecht, Netherlands, employing the Dutch Atmospheric Large-Eddy Simulation (DALES) model under various atmospheric conditions.
Residential wood combustion is a major source of urban air pollution, especially during winter months. This research aims to quantify the distribution and distance traveled by pollutants from their release source. By using DALES, detailed analyses of atmospheric variables and pollutant concentration fields are conducted, providing valuable insights into how atmospheric stability influences pollutant spread.
The results show that atmospheric stability significantly affects pollutant dispersion. Higher pollutant concentrations were generally observed near the surface under stable and very stable conditions as compared to neutral conditions, due to restricted vertical motions that limit the vertical dispersion of pollutants. Additionally, under stable conditions, pollutant concentrations remained elevated farther from the source, affecting residents who do not live close to the emission source. The study also compared the performance of DALES with commonly used Gaussian plume models (GPMs) to evaluate their performance in urban environments and under different atmospheric conditions. Three schemes that provide the dispersion parameters for the GPMs are tested to determine their accuracy in representing the DALES results. The comparison reveals that, while GPMs offer a general overview of pollutant distribution, they often fail to accurately capture concentration decay rates or the spatial extent of the plume.
The study concludes that further research should investigate the impact of atmospheric stability on air pollutant dispersion in urban environments. It also highlights the limitations of Gaussian Plume Models (GPMs), which often simplify processes occurring in the boundary layer. In urban settings, where the urban geometry plays a significant role in pollutant dispersion, DALES proves to be more effective than GPMs, which cannot accurately capture the effects of buildings on the plume.