Estimating European emissions of ozonedepleting and greenhouse gases using observations and a modeling back-attribution technique

The Numerical Atmospheric Dispersion Modeling Environment (NAME) dispersion model driven by three‐dimensional (3‐D) synoptic meteorology from the Unified Model has been used to determine the fraction of air arriving at Mace Head, Ireland, from different European regions over a 6‐year period. These data, along with observations of pollutants at Mace Head and a best fit algorithm, have been used to derive emission estimates over Western Europe. The algorithm starts from randomly generated emission maps and iterates toward the best solution. Using an idealized case study, it has been shown to be effective at distinguishing between distinct source regions. The technique has been applied to two ozone‐depleting gases, CFC‐11 and CFC‐12, and two greenhouse gases, methane and nitrous oxide. The emissions derived compare favorably with existing inventories. The technique is able to provide information regarding the emission distribution across Europe and to estimate area and country contributions; information that for some species is not readily available by other means. It is a different methodology to those currently used and so is a useful tool in verifying existing inventories.