Stijn Naus, Joannes D. Maasakkers, Ritesh Gautam, Mark Omara , Roelof Stikker, Allard Veenstra, Brian Nathan, Itziar Irakulis-Loitxate , Luis Guanter, Sudhanshu Pandey, Marianne Girard, Alba Lorente, Tobias Borsdorff, Ilse Aben 

Methane emissions from oil and gas production provide an important and partly mitigable contribution to anthropogenic global warming. Here, we investigate 2020 emissions from the largest gas field in Algeria, Hassi R'Mel, and the oil production dominated area of Hassi Messaoud. We first use methane data from the high-resolution (20 m) Sentinel-2 instrument to identify eleven point source super-emitters (1 in Hassi R'Mel and 10 in Hassi Messaoud), ten of which correspond to unlit flares likely related to oil production. For each point source we construct emission timeseries based on methane enhancements as observed with Sentinel-2. We integrate this information in a transport model inversion that uses methane data from the coarser (7.5 x 5km2) but higher-precision TROPOMI instrument to estimate emissions from both diffuse area sources and the 11 super-emitting point sources (> 1 t/hr individually). Compared to the bottom-up inventory of Scarpelli et al. (2022) for 2019 that is aligned with UNFCCC-reported emissions, we find that 2020 emissions in Hassi R'Mel (0.16 [0.11-0.22] Tg/yr) are lower by 53 [24-73]%, and emissions in Hassi Messaoud (0.22 [0.13-0.28] Tg/yr) are higher by 79 [4-188]%. Both the Sentinel-2 analysis and the TROPOMI-based emissions indicate that a much larger fraction of Algeria's methane emissions come from oil production than national reporting suggests. Additionally, we find that although in both regions diffuse area sources constitute the majority of emissions, relatively few space-detected super-emitters also provide a large contribution to the total area emissions (24 [12-40]% in Hassi R'Mel; 49 [27-71]% in Hassi Messaoud). The importance of both super-emitters and diffuse area sources indicates that mitigation efforts should address both the largest super-emitters, as well as include a wider portfolio of mitigation measures to improve oil and gas infrastructure in general. Our analysis shows that synergistic use of Sentinel-2 and TROPOMI, both with frequent global coverage, can produce a unique and detailed emission characterization of oil and gas production areas. Producing comparable emission characterizations for other areas is an important next step, as the contribution from super-emitters to total area emissions will differ between regions.