Gaussian plume equation dispersion parameters

Pasquill s dispersion parameters were restated in terms of a-y and Cj by Gifford (14, 15) to allow their use in the Gaussian plume equations. The... 

As an example of the use of the Gaussian plume equations using the Pasquill-Gifford dispersion parameters, assume that a source releases 0.37 g s of a pollutant at an effective height of 40 m into the atmosphere with the wind blowing at 2 m s . What is the approximate distance of the maximum concentration, and what is the concentration at this point if the atmosphere is appropriately represented by Pasquill stability class B ... 

The basic Gaussian plume dispersion parameters are ay and a. The essential theoretical result concerning the dependence of these parameters on travel time is for stationary, homogeneous turbulence (Taylor, 1921). Consider marked particles that are released from the origin in a stationary, homogeneous turbulent flow with a mean flow in the x direction. The y component, y, of the position of a fluid particle satisfies the equation... 

This equation represents a Gaussian distribution, where C (Bq.m 3) represents the radionuclide concentration, Q (Bq.s1) the source strength, and H (m) the corrected source released height. Dispersion parameters, ay (m) and az (m), are the standard deviations of the plume concentration in the horizontal and vertical directions respectively. The atmospheric transport is done at wind-speed (height-independent), u (m.s1), to a sampling position located at surface elevation, z (m), and transverse horizontal distance, y (m), from the plume centre. 

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