An analytical inversion method for determining regional and global emissions of greenhouse gases: sensitivity studies and application to halocarbons

A new analytical inversion method has been developed to determine the regional and global emissions of long-lived atmospheric trace gases. It exploits in situ measurement data from three global networks and builds on backward simulations with a Lagrangian particle dispersion model. The emission information is extracted from the observed concentration increases over a baseline that is itself objectively determined by the inversion algorithm. The method was applied to two hydrofluorocarbons (HFC-134a, HFC-152a) and a hydrochlorofluorocarbon (HCFC-22) for the period January 2005 until March 2007. It was found that the global a posteriori emissions of the three species all increased from 2005 to 2006. Large increases were found for China, whereas the emission changes in North America and Europe were less systematic. For Europe, the a posteriori emissions of HFC-134a and HFC-152a were slightly higher than the a priori emissions reported to the UNFCCC. For HCFC-22, the a posteriori emissions for Europe were substantially higher than the a priori emissions used, which were based on HCFC consumption data reported to the UNEP. Combined with the reported strongly decreasing HCFC consumption in Europe, this suggests a substantial time lag between the reported time of the HCFC- 22 consumption and the actual time of the HCFC-22 emission. Conversely, in China where HCFC consumption is increasing rapidly according to the UNEP data, the a posteriori emissions are only about 40% of the a priori emissions. This reveals a substantial storage of HCFC-22 and potential for future emissions in China. This paper, published in one of the most important journals in the field of atmospheric sciences, shows how the research activity carried out by M. Maione is relevant in ascertaining the compliance of the various countries to important international agreements such the Montreal and the Kyoto Protocols dealing with global change phenomena like the stratospheric ozone depletion and the global warming, respectively. Moreover, it testifies the collaboration with international and multidisciplinary research groups.