Modelling Dispersion Parameters in a Planetary Boundary Layer Dominated by Convection

Abstract

The Gaussian plume model concept is still important for estimating ground-level concentrations due to tall stack emissions and is usually suitable for regulatory use in air quality models. Improved dispersion algorithms in updated Gaussian models calculate the dispersion parameters σ_y and σ_z in terms of distinct scaling parameters for turbulence. In this work, we use the convective similarity theory and Taylor’s statistical diffusion theory to derive a general expression for the dispersion parameters in a planetary boundary layer dominated by convection. The novelty is use Taylor’s theory to construct a relation for the dispersion parameters that is described only in terms of the universal characteristics of the turbulent field in a convective boundary layer (CBL), eliminating in this manner, the necessity of dispersion parameters fitting from diffusion experiments.