Integrating MethaneAIR aircraft and TROPOMI satellite observations in the Integrated Methane Inversion (IMI) to optimize methane emissions

Abstract. The MethaneAIR aircraft remote sensing instrument observes methane dry air column mixing ratios (X_CH4) over ~100×100 km² scenes with sub-km resolution, from which methane emissions can be inferred by inverse analysis with an atmospheric transport model. It emulates the MethaneSAT satellite instrument launched in March 2024 to quantify emissions from oil/gas production regions. We show here how the single day MethaneAIR observations can be integrated with the global continuous but relatively coarse and sparse observations from the TROPOMI satellite instrument into a common Integrated Methane Inversion (IMI) platform for optimizing methane emissions. The IMI, originally designed for TROPOMI, is used here with 12×12 km² spatial resolution and lognormal error probability density functions (PDFs) for prior estimates. Application to two scenes in oil/gas production basins of the western US shows remarkable consistency between independent MethaneAIR (single day) and TROPOMI (monthly) inversions including for emission hotspots, with some differences that may reflect temporal variability of emissions. The IMI is able to optimize emissions even when starting from a very poor prior estimate. Using TROPOMI inversion results as prior estimate improves the MethaneAIR inversions by correcting emissions upwind of the MethaneAIR observation scenes and by adding information to the original prior estimate.