Correlations for and Based on Pasquill Stability Classes

The correlations for ay and az in the previous subsection require knowledge of atmospheric variables that may not be available. In that case, one needs correlations for a, and jz based on readily available ambient data. The Pasquill stability categories A through F introduced in Chapter 16 provide a basis for such correlations. 

FIGURE 18.4 Correlations for crv based on the Pasquill stability classes A to F (Gifford 1961). These are the so-called Pasquill-Gifford curves. 

For use in dispersion formulas it is convenient to have analytical expressions for ctv and ct- as functions of x. Many of the empirically determined forms can be represented by the power-law expressions 

TABLE 18.3 Coefficients in Gaussian Plume Dispersion Parameter Correlations  

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