The Impact of the Prairie Grass and the St. Louis Dispersion Experiments on Dispersion Modeling Practice
The St. Louis study, conducted over the period 1963-1965, consisted of a series of 26 daytime and 16 evening experiments in which fluorescent zinc cadmium sulfide particles were released near ground level at two different locations in downtown St. Louis. Each release, which was typically 1 hour long, was sampled on arcs at 800 m to 16 km from the release point. A meteorological network of three stations on the outer area of the sampling area and an instrumented television tower tracked wind, temperature, and relative humidity. McElroy and Pooler (1968, Volume II) grouped the measured plume spreads using meteorological indices of dispersion, such as Richardson number and Pasquill stability class. Briggs (1974) fitted analytical curves to the data presented by McElroy-Pooler to formulate the urban dispersion curves used in EPA models such as ISC. The dispersion curves have also been used to interpret data collected in a recent field study conducted in Salt Lake City (Hanna et al., 2003).
This paper provides details of the design and implementation of these two classic dispersion experiments, the Prairie Grass and St. Louis experiments. It then describes the analysis of the observed data (Venkatram, 2005), and discusses the major impact of these field studies on the development of dispersion models that are currently used.
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