ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-11-7817-2011 Radon activity in the lower troposphere and its impact on ionization rate: a global estimate using different radon emissions Zhang K. 1 10 Feichter J. 1 Kazil J. 2 9 Wan H. 1 Zhuo W. 3 Griffiths A. D. 4 Sartorius H. 5 Zahorowski W. 4 Ramonet M. 6 Schmidt M. 6 Yver C. 6 Neubert R. E. M. 7 Brunke E.-G. 8 Max Planck Institute for Meteorology, Hamburg, Germany Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, Colorado, USA Institute of Radiation Medicine, Fudan University, Shanghai, China Australian Nuclear Science and Technology Organisation, Lucas Heights NSW 2234, Australia Federal Office for Radiation Protection (BfS), Salzgitter, Germany Laboratoire des Sciences du Climat et de l'Environnement, IPSL, CEA, UVSQ, CNRS, Gif-sur-Yvette, France Centre for Isotope Research, University of Groningen, Groningen, The Netherlands South African Weather Service, Stellenbosch, South Africa NOAA Earth System Research Laboratory (ESRL), Boulder, Colorado, USA now at: Pacific Northwest National Laboratory, Richland, Washington, USA 03 08 2011 11 15 7817 7838 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/11/7817/2011/acp-11-7817-2011.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/11/7817/2011/acp-11-7817-2011.pdf

The radioactive decay of radon and its progeny can lead to ionization of air molecules and consequently influence aerosol size distribution. In order to provide a global estimate of the radon-related ionization rate, we use the global atmospheric model ECHAM5 to simulate transport and decay processes of the radioactive tracers. A global radon emission map is put together using regional fluxes reported recently in the literature. Near-surface radon concentrations simulated with this new map compare well with measurements. <br><br> Radon-related ionization rate is calculated and compared to that caused by cosmic rays. The contribution of radon and its progeny clearly exceeds that of the cosmic rays in the mid- and low-latitude land areas in the surface layer. During cold seasons, at locations where high concentration of sulfuric acid gas and low temperature provide potentially favorable conditions for nucleation, the coexistence of high ionization rate may help enhance the particle formation processes. This suggests that it is probably worth investigating the impact of radon-induced ionization on aerosol-climate interaction in global models.

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