Dispersion from a continuous ground‐level source investigated by a K model

A crosswind‐integrated K model with wind profiles and K profiles described by Monin‐Obukhov similarity relations is solved numerically for the case of the release of a passive substance from a point source at ground level. An extensive analysis is undertaken to compare the numerical model results with experimental results from the Prairie Grass dispersion experiments. Simulations of these experiments are carried out with and without deposition. It is shown that the numerical solution of the diffusion equation yields a good approximation to both the vertical concentration profile and the crosswind‐integrated ground‐level concentrations when consideration is given to the effect of deposition of the tracer. Despite considerable scatter, the measurements are seen to support the use of the eddy diffusivity of heat rather than the modified expression of that of momentum. For comparison Dyer's (1974) expressions for the eddy diffusivity of heat and momentum are also used; only minor differences are found in the performance of the two sets of expressions.