ISCST3 Tech Guide

Gaussian Plume Air Dispersion Model

7.1.8 The Smoothing Function

As shown by Equation (2-1), the rectangular concentration distribution within a given angular sector is modified by the function S{2} which smooths discontinuities in the concentration at the boundaries of adjacent sectors. The centerline concentration in each sector is unaffected by contribution from adjacent sectors. At points off the sector centerline, the concentration is a weighted function of the concentration at the centerline and the concentration at the centerline of the nearest adjoining sector. The smoothing function is given by:

Formula

Where:

2j´ = the angle measured in radians from north to the centerline of the jth wind-direction sector

2´= the angle measured in radians from north to the receptor point (R, 2) where R, defined above for equation 2-1, is measured from the lateral virtual source