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Dispersion Modeling of Ground-level Area Sources of Particulate

B.K. Fritz, G.W. Zwicke, B.W. Shaw and C.B. Parnell


The modeling of air pollution dispersion is becoming increasingly more important to the regulatory process. With the passage of a new more stringent set of National Ambient Air Quality Standards, sources are going to be more heavily regulated. In addition, regulation of fugitive sources will be more emphasized than they have been historically. Dispersion models that provide accurate estimations of downwind concentrations of pollutant from fugitive sources are needed to insure reliable and fair regulation of these sources. Presently accepted Gaussian based models inaccurately apply time averages to calculated concentrations, and use dispersion profiles that do not accurately describe dispersion of pollutants from ground-level sources. These models apply a one-hour time period to a concentration that is referenced in literature as and is commonly accepted as a ten minute concentration. This results in a one-hour concentration that is excessively high. This "one-hour" concentration, in effect, assumes that a single wind speed and wind direction exist for the entire time period. This is inappropriate. A new model is being developed that accounts for the meteorological variation over smaller time increments, which results in predicted concentrations that are appropriate for the modeled time period. The new model also applies a dispersion profile that more accurately reflects dispersion from ground-level releases. The result is a model that more accurately predicts concentrations downwind of ground-level sources.

Reprinted from Proceedings of the 1998 Beltwide Cotton Conferences pp. 1658 - 1663
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998