Description of a recent Nordic mesoscale dispersion experiment over a land-water-land area (the Oeresund experiment)

The experimental set-up is described together with some results from a project that was carried out to investigate the nature of the turbulence and atmospheric dispersion over a mesoscale region with warm land and cold water surface. The measuring campaign was carried out as a joint effort of 15 institutions located in the Nordic countries (Denmark, Finland, Norway and Sweden), in Belgium, Germany and in the Netherlands. The experiment took place in the Oresund region from May 15 to June 15, 1984. Use was made of a large proportion of the available meso- and micro-meteorological instrumentation in the Nordic countries including six three-component doppler sodars. The atmospheric dispersion process in the area was investigated by carrying out tracer experiments as well as by tetroon-flights. The tracer was released from about 100 meters height. The release took place over a period of several hours for each experiment. When released the tracer was advected over the Oresund water surface for about 20 km. When the tracer plume reached th opposite coast it was sampled at ground level by sampling units positioned in an arc close to the water front as well as inland. Measurements of instantaneous tracer concentrations were carried out from a van, from a boat, and from an airplane. The project performs a thorough mapping in time and space of the meteorological parameters that control the atmospheric dispersion process. These measurements, in addition to the results from the tracer experiments, will be available for general scientific use. (author)