AERMOD Tech Guide

Gaussian Plume Air Dispersion Model

8.3.5 Measured Turbulence

All measured turbulence values are passed to AERMOD if the hour is non-missing. This is true even for those levels where the wind speed is below uTH .

Based on measurements with research grade instruments, reasonable minimum turbulence levels in non-calm conditions for vertical turbulence (w ) and lateral turbulence (v ) w v values are set by AERMOD to 0.02 m/s and 0.2 m/s, respectively.

Although these lower limits are applied to the measured values of the turbulence the calculated profile values of w &v are not subjected to any lower limits. We do not w v restrict these estimated profiles because it would bias the calculation of the effective values of turbulence, which are averages through the layer between the receptor and the plume height, in determining the dispersion of the plume.