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

Flux estimates of CO 2 , CH 4 , N 2 O, and CFCs over western Europe have been inferred from continuous atmospheric records of these species at the atmospheric research station of Mace Head, Ireland. We use radon ( 222 Rn) which has a fairly uniform source over continents as a reference compound to estimate unknown sources of other species. The correlation between each species and 222 Rn is calculated for a suite of synoptic events that have been selected in the Mace Head record over the period 1996/97. In the following, we describe the method and its uncertainties, and we establish data selection criteria that minimize the influence of local sources over Ireland, in the vicinity of the station, in order to select synoptic events originating from western Europe. We estimate western European flux densities of 45–30 10 3 kg C km −2 month −1 during wintertime for CO 2 , of 4.8–3.5 10 3 kg CH 4 km −2 yr −1 , 475–330 kg N 2 O km −2 yr −1 , 2.5–1.8 kg CFC‐11 km −2 yr −1 for 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.