European greenhouse gas emissions estimated from continuous atmospheric measurements and radon 222 at Mace Head, Ireland

Flux estimates of CO2, CH4 N2O, and CFCs over western Europe have been infe rred from continuous atmospheric records of these species at the atmospheri c research 771 station of Mace Head, Ireland. We use radon ( Rn) which has a fairly uniform source over continents as a reference compound to estimate unknown sources of other species. The Rn-222 is calculated for a suite of synoptic events that correlation between each species and have been selecte d in the Mace Head record over the period 1996/97. In the following, we des cribe the method and its uncertainties, and we establish data selection cri teria that minimize the influence of local sources over Ireland, in the vic inity of the station, in order to select synoptic events originating from w estern Europe. We estimate western European flux densities of 45-30 10(3) k g C km(-2) month(-1) during wintertime for CO2, of 4.8-3.5 10(3) kg CH4 km( -2) yr(-1), 475-330 kg N2O km(-2) yr(-1) 2.5-1.8 kg CFC-11 km(-2) yr(-1) fo r CFC-11 and 4.2-2.9 kg CFC-12 km(-2) yr(-1) for CFC-12. Our estimates are independent, although in good agreement with those produced by inventories, except for CFC-11 where our estimate is much lower than the inventory.