Articles | Volume 15, issue 12
Atmos. Chem. Phys., 15, 7049–7069, 2015
Atmos. Chem. Phys., 15, 7049–7069, 2015

Research article 30 Jun 2015

Research article | 30 Jun 2015

Estimating global and North American methane emissions with high spatial resolution using GOSAT satellite data

A. J. Turner1, D. J. Jacob1,2, K. J. Wecht2, J. D. Maasakkers1, E. Lundgren1, A. E. Andrews3, S. C. Biraud4, H. Boesch5,6, K. W. Bowman7, N. M. Deutscher8,9, M. K. Dubey10, D. W. T. Griffith8, F. Hase11, A. Kuze12, J. Notholt9, H. Ohyama12,13, R. Parker5,6, V. H. Payne7, R. Sussmann14, C. Sweeney3,15, V. A. Velazco8, T. Warneke9, P. O. Wennberg16, and D. Wunch16 A. J. Turner et al.
  • 1School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA
  • 2Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts, USA
  • 3NOAA Earth System Research Laboratory, Boulder, Colorado, USA
  • 4Lawrence Berkeley National Laboratory, Berkeley, California, USA
  • 5Earth Observation Science Group, Department of Physics and Astronomy, University of Leicester, Leicester, UK
  • 6National Centre for Earth Observation, University of Leicester, Leicester, UK
  • 7Jet Propulsion Laboratory/California Institute of Technology, Pasadena, California, USA
  • 8Centre for Atmospheric Chemistry, University of Wollongong, NSW, Australia
  • 9Institute of Environmental Physics, University of Bremen, Bremen, Germany
  • 10Los Alamos National Laboratory, Los Alamos, New Mexico, USA
  • 11Karlsruhe Institute of Technology, IMK-ASF, Karlsruhe, Germany
  • 12Japan Aerospace Exploration Agency, Tsukuba, Ibaraki, Japan
  • 13Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Aichi, Japan
  • 14Karlsruhe Institute of Technology, IMK-IFU, Garmisch-Partenkirchen, Germany
  • 15Cooperative Institute for Research in Environmental Sciences, University of Colorado at Boulder, Boulder, Colorado, USA
  • 16California Institute of Technology, Pasadena, California, USA

Abstract. We use 2009–2011 space-borne methane observations from the Greenhouse Gases Observing SATellite (GOSAT) to estimate global and North American methane emissions with 4° × 5° and up to 50 km × 50 km spatial resolution, respectively. GEOS-Chem and GOSAT data are first evaluated with atmospheric methane observations from surface and tower networks (NOAA/ESRL, TCCON) and aircraft (NOAA/ESRL, HIPPO), using the GEOS-Chem chemical transport model as a platform to facilitate comparison of GOSAT with in situ data. This identifies a high-latitude bias between the GOSAT data and GEOS-Chem that we correct via quadratic regression. Our global adjoint-based inversion yields a total methane source of 539 Tg a−1 with some important regional corrections to the EDGARv4.2 inventory used as a prior. Results serve as dynamic boundary conditions for an analytical inversion of North American methane emissions using radial basis functions to achieve high resolution of large sources and provide error characterization. We infer a US anthropogenic methane source of 40.2–42.7 Tg a−1, as compared to 24.9–27.0 Tg a−1 in the EDGAR and EPA bottom-up inventories, and 30.0–44.5 Tg a−1 in recent inverse studies. Our estimate is supported by independent surface and aircraft data and by previous inverse studies for California. We find that the emissions are highest in the southern–central US, the Central Valley of California, and Florida wetlands; large isolated point sources such as the US Four Corners also contribute. Using prior information on source locations, we attribute 29–44 % of US anthropogenic methane emissions to livestock, 22–31 % to oil/gas, 20 % to landfills/wastewater, and 11–15 % to coal. Wetlands contribute an additional 9.0–10.1 Tg a−1.

Final-revised paper