Using a combination of two models in tracer simulations

The use of a combination of two models, a Lagrangian meso-scale model and a long-range transport Eulerian model, in a model for studying the air pollution caused by a single but strong emission source is discussed. It is explained why it is worthwhile to apply a combination of two models in such a situation. The rules that can be used in the coupling procedure are described. The reliability of the combined model is tested both by using the well-known rotation test and by applying it to study both the Chernobyl accident and the two ETEX-releases. The results obtained by the combined model are visualized by using modern graphic tools. The distribution of the radioactivity from the Chernobyl accident and the concentrations from the ETEX-releases have been animating by producing a short movie. Some plans for the future research are briefly discussed.