Central Campus Air Quality Model (CCAQM) Instructions
Point Sources
Point source
models are a way to represent a steady stream of pollutants being
ejected from a smokestack. The point source model used in this
tutorial is a Gaussian distribution, which is a statistical
representation of the dispersion of emissions from the stack in a
given space.
Model Inputs
The Gaussian
distribution of a point source is given by the following equation
Where:

C(x,y) =
concentration at ground level at point (x,y) in units mg/m^{3}

x = distance
directly downwind, km

y =
horizontal distance from the plume centerline, m

Q = emission
rate of pollutants, mg/s

u_{H}
= average windspeed at effective stack height, m/s

H = effective
stack height, m

σ_{y}^{
}
=
horizontal dispersion coefficient, a standard deviation, m

σ_{z}
= vertical dispersion coefficient, m
Similarly
to the line source model, horizontal and vertical dispersion
coefficients are calculated in the following way:
σ_{y}(x)
= ax^{0.894}
σ_{z}(x)
= cx^{d} + f
Note: x is distanced described in km,
however, the solutions to σ_{z}(x)
& σ_{y}(x) solve in terms of meters so no conversion
needs to take place to input into the Gaussian equation above.
Parameters for calculating dispersion coefficients
