Short-Range Diffusion Experiments in Unstable Conditions over Inhomogeneous Terrain

Equipment to measure the dispersion of a release of the tracer sulphurhexafluoride (SF6) was developed and nine experiments were then performed at the Riso National Laboratory in the period April to July 1976. The tracer was released at 60 m from the Riso meteorological tower, situated on a peninsula in the Roskilde Fjord, Denmark, and was sampled at ground-level positions distributed over a crosswind line about 1 km downwind. During the experiments, the turbulent wind velocity components were measured at the height of release with a three-dimensional ultrasonic anemometer. The experiments were performed in westerly winds, hence inhomogeneity in surface roughness between the fjord and the site