Grid

For this model we lay out a grid over the Salt Lake valley with squares $a = 500$ m on a side. On each square we build a box $h$ meters high. The height is variable over a range of a few hundred meters to a kilometer and corresponds to a boundary layer imposed by a temperature inversion. We assume that this height is constant over the entire valley.

In each $x,y$ box we represent the mass of pollutant in $kg$ by $m(x,y,t)$. The concentration in mass per unit volume ($kg/m^3$) is then

$$C(x,y,t) = m(x,y,t)/(a^2h)$$ (1)