Keywords: averaging time, atmospheric dispersion, buildings, field measurement variability, obstacle array, peak-to-mean concentration ratio, mean wake concentrations, air pollution, air quality
Effect of averaging time on mean concentrations in building influenced dispersion
Tracer gas was released upwind of a cubical model building in the field, under neutral atmospheric conditions, in order to investigate the dependence of mean wake concentrations on averaging time. Two different experimental settings were examined, with the obstacle isolated or embedded within an array of similar obstacles. The averaging periods examined ranged between 10 s and 15 min. A power law function described well the dependence of mean concentrations on averaging time. The absolute values of the power law exponent observed in the near-wake region were lower than those observed in open terrain dispersion, for both experimental settings.