Gaussian Plume Model and Dispersion Coefficients
Author: John M. Cimbala, Penn State University
Latest revision: 13 February 2014
Procedure to calculate the dispersion coefficients y and z :
1. Determine the Stability Classification of the atmosphere, A, B, … using Table 20.1.
2. Determine constants a, b, …, f using Table 20.2.
3. Calculate y and z :  y  ax b and  z  cx d  f , with x in units of km and y and z in units of m.
Gaussian plume model to estimate mass concentration of air pollutant at location (x, y, z):
2 
   2 
m j , s
z  H   
 1 y
exp     
With ground absorption, c j 
  , H  hs   h = effective stack height.
 
2 U  y z
 2   y    z   

 
y
 1

exp  
With ground reflection, c j 


2 U  y z
2 
  y

2
2
 
  z  H   
y
 1


 exp  
   z   

2 
  
 
  y
m j , s
2
2
  z  H   
 

   z    .
  
 

Notice: Use Class D for overcast conditions.
Tables scanned from Cooper, C. D. and Alley, F. C. Air Pollution Control: A Design Approach, Edition 4, Waveland Press, Inc.,
Long Grove, IL, 2011, pp. 662-663.