Keywords: averaging time, fluctuations, plumes, sonic anemometer, stability, turbulence
Effects of averaging time on predicted gas concentrations
The potential consequences of a particular gaseous emission usually relate to a specific averaging time. However, the averaging time associated with gas monitoring data in the region of a discharge may differ from the averaging time implicit in a model employed to predict the concentration resulting from that emission. Tables of factors exist for taking account of such differences and recent models include expressions that convert predicted values to the appropriate averaging time. This paper presents the results of a study of the factors used in these regulatory tables, and makes comparisons with the equivalent factors deduced from runs with a gas dispersion model and sonic anemometer observations.