AERMOD Tech Guide
6.5 Plume Rise Calculations in AERMOD
For the direct source, hd is taken from (Briggs, 1984) as:
It should be noted that uP is the wind speed used for calculating plume rise. In the CBL uP is set equal to u{hs}. While in the SBL uP is initially set equal to u{hs} but its final value is determined by iterating.
The indirect source, which we include to treat the no flux condition at z = zi , uses a modified reflection approach in which the reflected vertical velocity is adjusted by the addition of a plume rise term h , designed to keep the plume aloft (Weil et al., 1997), such that
The height that the penetrated source achieves above zi is calculated as the equilibrium plume rise in a stratified environment and is determined by the source buoyancy flux, the stable stratification above zi , and the mean wind speed. In line with Weil et al. (1997), we assume that the plume I height h is the centroid of the plume material above the inversion and take hep = hs+ heq for fP = 0 or complete penetration. However, for partial penetration ( fP > 0), hep is chosen as the average of the heights of the upper plume edge hs + 1.5heq and zi , or
where heq is defined in eq. (68).