AERMOD Tech Guide

Gaussian Plume Air Dispersion Model

3.2.2 Sensible Heat Flux(H) in the SBL

Having computed u* and * , AERMET calculates the surface heat flux from the definition for * found in eq. (17)

Equation (25)

AERMET limits the amount of heat that can be lost by the underlying surface to approximately 60Wm-2 . This value is based on a restriction that Hanna et al., (1986) placed on the product of * and u . That is, for typical conditions.

Equation (26)

When the heat flux, calculated from eq. (25), is such that * u*. > 0.05ms-1 K, AERMET recalculates u* . by substituting 0.05/u* into eq. (22) for * (u0 in eq. (22) is a function of *) and solving for u*. Using the recalculated value for u *., * is then calculated from eq. (26).