ISCST3 Tech Guide

Gaussian Plume Air Dispersion Model

6.1.3 Wind Speed Profile

The wind power law is used to adjust the observed wind speed, uref, from a reference measurement height, zref, to the stack or release height, hs. The stack height wind speed, us, is used in the Gaussian plume equation (Equation 1-1), and in the plume rise formulas described in Section 1.1.4. The power law equation is of the form:

Formula

where p is the wind profile exponent. Values of p may be provided by the user as a function of stability category and wind speed class. Default values are as follows:

Stability Category
Rural Exponent
Urban Exponent
A
0.07
0.15
B
0.07
0.15
C
0.10
0.20
D
0.15
0.25
E
0.35
0.30
F
0.55
0.30

The stack height wind speed, us, is not allowed to be less than 1.0 m/s.