Atmospheric dispersion experiments are carried out in Copenhagen under neutral and unstable conditions in order to study the atmospheric dispersion process in a built-up area. The tracer sulphurhexafluoride is released without buoyancy from a meterological instrumented tower at a height of 115 m, and then collected at ground-level positions in up to three crosswind series of tracer-sampling units, positioned 2–6 km from the point of release. In addition to standard meteorological profile measurements along the tower, the three-dimensional wind fluctuations at the height of release are measured. Characteristic dispersion parameters are estimated from the measured tracer concentrations (averaging time 1 hour), and compared to the dispersion parameters that can be calculated from the atmospheric parameters by various methods. Some of these methods (based on a stability-index) have been in common use for a long time, other (based on wind-fluctuation measurements) reflect recent research. The wind-fluctuation based methods turned out to compare most favourably with the results from the experiments. Based on these experiments a half-empirical model is devised for the prediction of the lateral and vertical dispersion parameters, σy and σZ, for elevated point sources in an urban area under neutral to unstable conditions.
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- Results from Elevated-Source Urban Area Dispersion Experiments Compared to Model Calculations
- Springer US
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