Probability Modeling of Concentration Fluctuation behind Building

Identifying geographic areas from which air pollutants enter the atmosphere is one of the most important information needed to develop effective pollution control strategies. Probability density function (PDF) modeling is a possible approach that can be used for estimating concentration fluctuation in pollutant plume dispersion in a stratified atmospheric boundary layer. Only few studies have been devoted to evaluate applications of PDF modeling to pollutant dispersion in an urban environment. This study was designed to investigate the diffusion fields in the boundary layer using obstacle model such as an isolated building model. We measured concentration fluctuations reported along the mean plume centerline at various downwind distances from the source at different heights with the frequency of 1KHz. Probabilistic analysis was performed on the concentration fluctuation, and the PDF of mean concentration, fluctuation intensity and crosswind mean-plume dispersion were developed. The PDF of the concentration fluctuation data have shown a significant non-Gaussian behavior. The lognormal distribution appeared to be the best fit to the shape of concentration measured in the boundary layer. We observed that the plume dispersion PDF near the source was shorter than the plume dispersion far from the source. Our findings suggest that the use of PDF technique in complex building environment can be a powerful tool to help understand the distribution and location of air pollutants.