A model for the dispersion of puffs into the planetary boundary-layer

A model for the dispersion of Gaussian puffs into the planetary boundary-la yer is presented. The model relies on the relative diffusion theory in whic h the rate of expansion of the puff is expressed in terms of the spectral p roperties of turbulence. A new spectral formulation for the turbulent veloc ities is used, which is valid for different stability conditions ranging fr om stable to convective. As a preliminary model evaluation, a continuous pl ume from the experimental campaign of Copenhagen is reproduced as a superpo sition of discrete emitted puffs. Comparison between predicted and measured ground-level concentration data shows a good agreement both for crosswind integrated concentrations and arcwise maxima.