We present the first sector-specific analysis of methane (CH4) emissions from the San Francisco Bay Area (SFBA) using CH4 and volatile organic compound (VOC) measurements from six sites during September – December 2015. We apply a hierarchical Bayesian inversion to separate the biological from fossil-fuel (natural gas and petroleum) sources using the measurements of CH4 and selected VOCs, a source-specific 1 km CH4 emission model, and an atmospheric transport model. We estimate that SFBA CH4 emissions are 166–289 Gg CH4/yr (at 95% confidence), 1.3–2.3 times higher than a recent inventory with much of the underestimation from landfill. Including the VOCs, 82 ± 27% of total posterior median CH4 emissions are biological and 17 ± 3% fossil fuel, where landfill and natural gas dominate the biological and fossil-fuel CH4 of prior emissions, respectively.
Seongeun Jeong, Xinguang Cui, Donald Blake, Ben Miller, Stephen Montzka, Arlyn Andrews, Abhinav Guha, Philip Martien, Ray Bambha, Brian LaFranchi, Hope Michelsen, Craig Clements, Pierre Glaize, and Marc Fischer. "Estimating methane emissions from biological and fossil-fuel sources in the San Francisco Bay Area" Geophysical Research Letters (2017): 486-495. doi:10.1002/2016GL071794