ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-11-10071-2011 TransCom continuous experiment: comparison of <sup>222</sup>Rn transport at hourly time scales at three stations in Germany Taguchi S. 1 Law R. M. 2 Rödenbeck C. 3 Patra P. K. 4 Maksyutov S. 5 Zahorowski W. 6 Sartorius H. 7 Levin I. 8 National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan Centre for Australian Weather and Climate Research, CSIRO Marine and Atmospheric Research, Aspendale, Victoria, Australia Max-Planck-Institute for Biogeochemistry, Jena, Germany Frontier Research Center for Global Change/JAMSTEC, Yokohama, Japan National Institute of Environmental Studies, Tsukuba, Japan Australian Nuclear Science and Technology Organization, Menai, New South Wales, Australia Federal Office for Radiation Protection, Freiburg, Germany Institut für Umweltphysik, University of Heidelberg, Germany 06 10 2011 11 19 10071 10084 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.net/11/10071/2011/acp-11-10071-2011.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/11/10071/2011/acp-11-10071-2011.pdf

Fourteen global atmospheric transport models were evaluated by comparing the simulation of <sup>222</sup>Rn against measurements at three continental stations in Germany: Heidelberg, Freiburg and Schauinsland. Hourly concentrations simulated by the models using a common <sup>222</sup>Rn-flux without temporal variations were investigated for 2002 and 2003. We found that the mean simulated concentrations in Heidelberg are related to the diurnal amplitude of boundary layer height in each model. Summer mean concentrations simulated by individual models were negatively correlated with the seasonal mean of diurnal amplitude of boundary layer height, while in winter the correlation was positive. We also found that the correlations between simulated and measured concentrations at Schauinsland were higher when the simulated concentrations were interpolated to the station altitude in most models. Temporal variations of the mismatch between simulated and measured concentrations suggest that there are significant interannual variations in the <sup>222</sup>Rn exhalation rate in this region. We found that the local inversion layer during daytime in summer in Freiburg has a significant effect on <sup>222</sup>Rn concentrations. We recommend Freiburg concentrations for validation of models that resolve local stable layers and those at Heidelberg for models without this capability.

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