||Estimating Plume Dispersion, A Recommended Generalized Scheme.
Irwin, John S. ;
||Environmental Sciences Research Lab., Research Triangle Park, NC.
Air pollution ;
Mathematical models ;
Turbulent flow ;
Wind velocity ;
Atmospheric dispersion ;
Gaussian plume models
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A generalized scheme is presented for estimating the vertical and horizontal Gaussian dispersion parameters for point sources whose release heights are greater than 10 meters. The scheme requires either estimates of or measurements of the standard deviation of the horizontal and vertical wind direction fluctuations at the effective height of release. During unstable conditions, the depth of the convectively mixed layer and the convective velocity scale are required as input to the scheme. During neutral/stable conditions, the scheme requires specification of the depth of surface based neutral/stable layer. Provisions are made for incorporating the induced dispersion resulting from buoyant plume rise and from horizontal wind direction shear in the vertical. No provisions are made for dispersion induced due to terrain interaction with the transport of the plume. The scheme incorporates the recommendations of the AMS workshop on stability classification schemes and sigma curves and is suggested for use in the interim while more field data is collected upon which a more complete scheme can be based.