Daniel Cusworth , Andrew Thorpe, Alana Ayasse, David Stepp, Joseph Heckler, Gregory Asner, Charles E. Miller, John Chapman, Michael Eastwood, Robert Green, Ben Hmiel, David Lyon, Riley Duren

Understanding, prioritizing, and mitigating methane (CH4) emissions requires quantifying methane budgets from facility scales to regional scales with the ability to differentiate between source sectors. We deployed a tiered observing system for multiple basins in the United States (San Joaquin Valley, Uintah, Denver-Julesberg, Permian, Marcellus). We quantify strong point source emissions (>10 kg CH4 h-1) using airborne high spatial resolution imaging spectrometers, then attribute them to sectors, and assess their intermittency with multiple revisits. We contextualize these point source emissions by comparing to total basin CH4 fluxes derived from inversion of Sentinel-5p satellite observations. We find that across basins point source make up on average 40% of the regional flux. We sampled some basins several times across multiple months and years and find a distinct bimodal structure to emission lifetimes: the total point source budget is split nearly in half by short- and long-lived emission events. With the increasing airborne and satellite observing capability planned for the near future, tiered observing systems can more fully account and attribute emission sources, which is needed to effectively and efficiently reduce methane emissions.