High-resolution inversion of methane emissions over Europe using the Community Inversion Framework and FLEXPART

Abstract. Constraining methane (CH4) emissions at high spatial and temporal resolution is critical for accurate European greenhouse gas budgets and mitigation policy. We use the Community Inversion Framework to estimate monthly CH4 fluxes across Europe (2017–2022) at 0.2°×0.2°, coupling FLEXPART and assimilating observations from 46 in situ stations, including Integrated Carbon Observation System (ICOS) and non-ICOS sites. Prior emissions combine anthropogenic inventories, biomass burning estimates, wetland models, and climatological natural sources. The inversion substantially improves agreement with atmospheric observations (r2=0.87, RMSE=24.4 ppb, mean bias=-2.1 ppb), performing best at northern European stations. For the European Union countries, together with the UK, Norway, and Switzerland, we estimate total methane emissions of 23.3±2.3 Tg CH4 yr−1, which is 6.6 % higher than the prior. For these countries, we found an average anthropogenic emissions of 17.6 Tg CH4 yr−1, with a decreasing trend of 0.3 Tg yr−1. This estimate exceeds the prior by 11 %, EDGARv8 by 4 %, and UNFCCC NGHGI (2023) by 3 %, while remaining consistent with recent studies. Country-level differences are notable, with higher emissions estimated for the Netherlands and Germany, and lower for Romania and Italy. Sectoral changes mainly reflect agricultural increases, alongside reductions in northern wetlands and southern geological sources. Sensitivity tests highlight the influence of spatial spread of emissions distribution assumptions and the importance of dense observational networks for refining regional CH4 budgets.