A model for the critical hourly concentration, receptor distance, and meteorological conditions for point sources with momentum-dominated plume rise

Abstract

A point source pollutant dispersion model is developed, allowing fast evaluation of the maximum one-hour-average ground concentrations, along with the corresponding critical receptor distance and meteorological conditions (wind speed and stability class) for urban and rural areas, with or without plume spread during plume rise. Site-specific meteorological data are not required, as the computed concentrations are maximized against all valid combinations of wind speed, stability class, and mixing heights. The model combines, under a constrained numerical extremization algorithm, the minimum mixing height model of Benkley and Schulman as adapted for urban areas by Economopoulos, with the dispersion relations of Briggs and Pasquill-Gifford for urban or rural settings respectively, the plume spread during plume rise correlation of Pasquill, and the momentum plume rise relations of Briggs. The model is particularly suited for air pollution management studies, as it allows fast screening of selected point sources in study areas and evaluation of the ways to have their impact reduced. Also, for regulatory purposes, as it allows accurate setting of minimum stack height requirements as a function of the exit gas volume and velocity, the pollutant emission rates, and their hourly concentration standards.