ISCST3 Tech Guide

Gaussian Plume Air Dispersion Model

6.5.8 The Plume Attenuation Correction Factor

Deflection of the plume by complex terrain features during stable conditions is simulated by applying an attenuation correction factor to the concentration with height in the sector of concern. This is represented by the variable CORR in Equation (1-93). The attenuation correction factor has a value of unity for receptors located at and below the elevation of the plume centerline in free air prior to encountering terrain effects, and decreases linearly with increasing height of the receptor above plume level to a value of zero for receptors located at least 400 m above the undisturded plume centerline height. This relationship is shown in the following equation:

Formula

Where:

CORR = attenuation correction factor, which is between 0 and 1

)Hr= height of receptor above undisturbed plume height, including height of receptor above local ground (i.e., flagpole height)