Irwin scheme giving an estimate somewhere in the middle. Observations are higher
than all predictions but closer to empirical methods (Briggs and P&G).
As shown in Figure 7 in case of stability C the Irwin method shows the
highest and the Draxler method the lowest y predictions with the remaining
schemes somewhere between the two. Observations are also closer to or higher
than Draxler/Taylor schemes.
In case of stability D (Figure 8), generally, the Draxler/Irwin schemes showestimates
on the higher side while Briggs and P&G are on the lower side. Observations
are higher than all schemes, but closer to Irwin/Draxler.
In the case of stable conditions (Figures 9 and 10), predictions from all the
schemes have less variation with one another in comparison to the one shown in
case of convective-neutral conditions and follow similar patterns. The observed
values in these cases are very high and mostly beyond the scale of the predictions
shown and therefore limited values are presented in the figures. It has also been
shown in the data set that the observed values do not showany set pattern (increasing
or decreasing).Many times the pattern also shows random variations.
Thus, fromthe above we may infer that dispersion coefficients follow an expected
trend during highly unstable conditions (A&B) which could also be represented