Facility-level CH4 emission rate summary at all facilities included in method comparisons. Study on-site estimates (SOE) are the sum of on-site direct measurements plus engineering estimates for unmeasured sources (stacked columns, black error bars). Tracer (left mark, blue error bars) and aircraft (right mark, red error bars) are overlaid at facilities where these measurements were compared to SOEs. Marker shape and fill indicate same/different day and the presence/absence of on-site observers, which influence the comparability of measurements. Bottom panel illustrates the fraction of the SOE contributed by each component; combustion slip contributes more than half of emissions at 16 of 17 facilities and accounts for three quarters of cumulative SOE emissions for these 17 facilities. Conversely, on-site direct measurements (ODMs) contribute less than one fourth of emissions at 15 of 17 facilities and accounts for 15% of the cumulative SOE for these 17 facilities. DOI: https://doi.org/10.1525/elementa.257.f1
