How a European network may help with estimating methane emissions on the French national scale

摘要: Abstract. Methane emissions on the national scale in France 2012 are inferred by assimilating continuous atmospheric mixing ratio measurements from nine stations of European network ICOS located and surrounding countries. To assess robustness fluxes deduced our inversion system based an objectified quantification uncertainties, two complementary set-ups computed analysed: (i) a regional run correcting for spatial distribution (ii) a sectorial activity sectors scale. In addition, results compared with produced framework inter-comparison exercise InGOS project. The seasonal variability is consistent between different set-ups, maximum summer, likely due to agricultural activity. However, very high monthly posterior uncertainties (up ≈ 65 to 74 % May June) make it difficult attribute a specific sector. On yearly scales, inversions range 3835 4050 Gg CH4 3570 4190 Gg CH4 runs, respectively, consistently products. These estimates 25 to 55 % higher than total bottom-up approaches (biogeochemical models natural emissions, plus inventories anthropogenic ones), pointing at missing or underestimated sources and/or sources. More specifically, set-up, as 66% larger reported UNFCCC. Uncertainties annual budget 108 and 312 Gg CH4, i.e, 3 to 8 %, runs smaller available products, proving added value top-down inversions. Therefore, even though surface used in 2012 does not allow us fully constrain all regions accurately, set-up makes possible provide French methane uncertainty less 10 % timescale. Additional sites deployed since 2012 would help finer temporal scales attributing sectors.