Detection and quantification of methane plumes with the MethaneAIR airborne spectrometer

Abstract. The MethaneAIR imaging spectrometer was originally developed as an airborne demonstrator of the MethaneSAT satellite mission. MethaneAIR enables accurate methane concentration retrievals from high-spectral-resolution measurements in the 1650 nm methane absorption feature at a nominal spatial sampling of 5 × 25 m. In this work, we present a computationally efficient data processing chain optimized for the detection and quantification of methane plumes with MethaneAIR. It involves the retrieval of methane concentration enhancements (ΔXCH4) with the high-precision matched-filter retrieval, which is applied to 1650 nm retrievals for the first time. Methane plumes are detected via visual inspection of the resulting ΔXCH4 maps. We evaluated the performance of this processing scheme with simulated plumes, intercomparison with other methods, and controlled methane releases. We applied this processing chain to MethaneAIR data mosaics acquired over the Permian Basin during flights in 2021 and 2023, which resulted in the detection of hundreds of point sources above 100–200 kg h−1, with a conservative detection limit of around 120 kg h−1. Our results show the consistency of MethaneAIR's ΔXCH4 matched-filter retrievals as well as their potential for the detection and quantification of methane point sources across large areas.