Turbulent diffusion-typing schemes: a review

Recent environmental concerns have greatly increased the need for turbulent typing schemes in atmospheric diffusion calculations. The standard methods by Brookhaven National Laboratory, Pasquill, the Tennessee Valley Authority, and others are reviewed, and differences, inconsistencies, and modifications to the basic schemes are discussed. Various exceptional flows occur to which existing turbulence typing schemes should not be applied directly: diffusion in near-calm, very stable conditions; diffusion over cities, water bodies, and irregular terrain; and diffusion in building wakes and near highways. Possible modifications to typing schemes in these cases are discussed. In all such exceptional cases, many more observational data are needed before reliable diffusion estimates can be made