Improving the accuracy of emission rate estimates under convective conditions with a dispersion-model-based method

Abstract

Turbulent diffusion from ground-level releases in the convective boundary layer is strongly influenced by both the non-Gaussianity of the vertical turbulent velocity and the correlations among components of turbulent velocities. However, currently, no models exist that account for both factors simultaneously. In this work, we demonstrate that non-Gaussianity plays a more significant role under strongly unstable stratification; therefore, it is preferable to use Lagrangian stochastic models that account for its effects. A new model for non-Gaussian turbulence is derived, following the method used by Luhar and Britter (1989)and Luhar and Sawford (1995), and is applied to calculate emission rates from ground-level releases. Modeling results indicate that estimates of ground-level emissions can be significantly improved using the model for non-Gaussian turbulence when the stratification is strongly unstable.