Halogenated greenhouse gas emissions over Central Europe inferred from ambient air measurements and 222-Rn activity

To check for compliance with the reduction targets defined under the Kyoto Protocol, each participating country has to report its greenhouse gas emissions to the UNFCCC (United Nations Framework Convention on Climate Change). These emissions are calculated using a bottom-up approach, by combining categories of compound use and specific activity (release) functions. The uncertainties of these estimates are not well defined, thereby making an independent validation of the reported emissions highly desirable. Top-down estimates based on atmospheric concentration measurements and using a reference species as a priori information are a promising method for independent emission estimates. For this purpose, atmospheric Radon (222-Rn) is very well suited due to its exactly known radioactive decay lifetime of 5.5 days and its homogeneous release over soil with comparatively small spatial and temporal variability.