Shushi Peng, Clément Giron, Gang Liu, Alexandre d'Aspremont, Antoine Benoit, Thomas Lauvaux , Xin Lin , Hugo De Almeidar Rodrigues, Marielle Saunois, Philippe Ciais

Accurate assessment of coal mine methane (CMM) emissions is a prerequisite for defining baselines and assessing the effectiveness of mitigation measures. Such an endeavor is jeopardized however by large uncertainties in current CMM estimates. Here, we assimilated images of methane column atmospheric mixing ratios observed by the TROPOMI space borne instrument in a high-resolution regional inversion to estimate CMM emissions in Shanxi, a province representing 15% of the global coal production. The emissions are estimated to be 8.5±0.6 and 8.6±0.6 Tg CH4 yr-1 in 2019 and 2020 respectively, close to upper bound of current bottom-up estimates. The monthly variations of emissions are well reproduced, including the drop and rebound in response to COVID-19 regulation. Data from more than a thousand of individual mines indicate that our estimated emission factors increase significantly with coal mining depth at prefecture level, that is the CH4 emission per volume of extracted coal. This result suggests that ongoing deeper mining will increase CMM emission intensity in the future, pressing needs for mitigation. Our results show robustness of estimating CMM emissions utilizing TROPOMI images, and highlight potential of monitoring methane leakages and emissions from satellites.