Inferring High-Resolution Global Methane Emissions and OH Concentrations using Blended TROPOMI+GOSAT Observations from 2019 to Present

Methane is a highly potent greenhouse gas, and a better understanding of its global sources and sinks is needed to guide climate policy. The methane concentration has been increasing rapidly over the past decade but the cause is unclear. Here we apply an analytical inversion of blended TROPOMI+GOSAT satellite observations of atmospheric methane with the Integrated Methane Inversion (IMI) tool to infer monthly methane emissions at 2°x2.5° resolution together with hemispheric OH concentrations from 2019 to present. The inversion uses best prior emission estimates from bottom-up inventories including the Global Fuel Emission Inventory (GFEI) version 3, the new Global Rice Paddy Inventory (GRPI), and the new global inventory for hydroelectric reservoirs (ResMe). Averaging kernel sensitivities demonstrate the capability of the inversion to optimize the OH sink of methane independently of emissions. Varying inversion parameters produces an ensemble of solutions to estimate uncertainties. We interpret the results in terms of the relative contributions of sources and sinks in driving the global methane increase, and the contributions of emissions from different regions and sectors. We explore the sensitivity of results to a large ensemble of wetland inventories used as prior estimates. The IMI-based system enables continuous low-latency global monitoring of monthly methane emissions.