Quantifying methane emissions from the global scale down to point sources using satellite observations of atmospheric methane
Daniel Jacob, Daniel J. Varon, Daniel Cusworth, Philip E. Dennison, Christian Frankenberg, Ritesh Gautam, Luis Guanter, J. L. Kelley, Jason McKeever, Lesley Ott, Benjamin Poulter, Zhen Qu, Andrew K. Thorpe, John R. Worden, Riley Duren
Abstract
Abstract. We review the capability of current and scheduled satellite observations of atmospheric methane in the shortwave infrared (SWIR) to quantify methane emissions from the global scale down to point sources. We cover retrieval methods, precision and accuracy requirements, inverse and mass balance methods to infer emissions, source detection thresholds, and observing system completeness. We classify satellite instruments as area flux mappers and point source imagers, with complementary attributes. Area flux mappers are high-precision (< 1 %) instruments with 0.1–10 km pixel size designed to quantify total methane emissions on regional to global scales. Point source imagers are fine-pixel (< 60 m) instruments designed to quantify individual point sources by imaging of the plumes. Current area flux mappers include GOSAT (2009–present), which provides a high-quality record for interpretation of long-term methane trends, and TROPOMI (2018–present) which provides global continuous daily mapping to quantify emissions on regional scales. Current point source imagers include the GHGSat constellation and several hyperspectral and multispectral land imaging sensors (PRISMA, Sentinel-2, Landsat-8/9, WorldView-3), with detection thresholds in the 100–10000 kg h-1 range. Future area flux mappers including MethaneSAT, GOSAT-GW, MicroCarb, GeoCarb, and CO2M will increase the capability to quantify emissions from source regions, and the MERLIN lidar will improve observation of the Arctic. The future constellation of Carbon Mapper point source imagers will achieve high observing system completeness for point sources through high spatial coverage and frequent return times.