ACPD Atmospheric Chemistry and Physics Discussions ACPD 1680-7375 Copernicus GmbH Göttingen, Germany 10.5194/acpd-2-825-2002 Modelling transport and deposition of caesium and iodine from the Chernobyl accident using the DREAM model Brandt J. 1 Christensen J. H. 1 Frohn L. M. 1 National Environmental Research Institute, Department of Atmospheric Environment, Frederiksborgvej 399, P.O. Box 358, DK-4000 Roskilde, Denmark 24 06 2002 2 3 825 874 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys-discuss.net/2/825/2002/acpd-2-825-2002.html The full text article is available as a PDF file from http://www.atmos-chem-phys-discuss.net/2/825/2002/acpd-2-825-2002.pdf

A tracer model, DREAM (the Danish Rimpuff and Eulerian Accidental release Model), has been developed for modelling transport, dispersion and deposition (wet and dry) of radioactive material from accidental releases, as the Chernobyl accident. The model is a combination of a Lagrangian model, that includes the near source dispersion, and an Eulerian model describing the long-range transport. The performance of the transport model has previously been tested within the European Tracer Experiment, ETEX, which included transport and dispersion of an inert, non-depositing tracer from a controlled release. The focus of this paper is the model performance with respect to the deposition of <sup>137</sup>Cs, <sup>134</sup>Cs and <sup>131</sup>I from the Chernobyl accident, using different relatively simple and comprehensive parameterizations. The performance, compared to measurements, of different combinations of parameterizations of wet and dry deposition schemes has been evaluated, using different statistical tests.