Coordinated satellite, aircraft, and ground-based observations of a large transient methane release

Tai-Long He, Daniel J. Varon , Shobha Kondragunta, Xinrong Ren, Mark Cohen, Brian J. Carroll, Nathan Malarich, Jeffrey Peischl, Tobias A. de Jong , Jelmar Gerritsen, Joannes D. Maasakkers, Daniel H Cusworth, Riley Duren, Steven Brown, Carsten Warneke, Colm Sweeney, Phillip Stratton, Alan Brewer, Sunil Baidar, Ezra Levin

We present the results of a Very Large Methane Release (VLMR) experiment evaluating methane retrievals from the Geostationary Operational Environmental Satellites (GOES) Advanced Baseline Imagers (ABIs) and multiple low-Earth-orbit satellite instruments with high point-source detection thresholds. The experiment coordinated observations of a U.S. gas pipeline blowdown with nine satellites, an aircraft, and a truck-based mobile laboratory. We used the GOES-16, -18, and -19 ABIs with revisits every 10 min to 7 s to quantify release magnitude and associated uncertainty. Best methane retrieval precision of 7% was achieved in the 30-s mesoscale scan modes averaged to 5 min, yielding an estimated methane plume detection threshold of 15–30 t h^-1 per m s^-1 of wind. GOES detected total emissions of 370±30 t over 44–65 min from two release points. Source rate and mass estimates are broadly consistent across measurement platforms, but the total detected release mass is ~25% lower than that reported by the operator based on pipeline volume and pressure. This discrepancy may reflect late-stage emissions below satellite detection thresholds and indicates a potential low bias in satellite estimates of total emissions from large transient releases. Coordinated field experiments such as VLMR can complement existing controlled-release satellite evaluation programs by providing a framework to validate observations of very large methane point sources.