Preprints
https://doi.org/10.5194/egusphere-2022-948
https://doi.org/10.5194/egusphere-2022-948
 
30 Sep 2022
30 Sep 2022

A high-resolution satellite-based map of global methane emissions reveals missing wetland, fossil fuel and monsoon sources

Xueying Yu1,2, Dylan B. Millet1, Daven K. Henze3, Alexander J. Turner4, Alba Lorente Delgado5, A. Anthony Bloom6, and Jianxiong Sheng7 Xueying Yu et al.
  • 1Department of Soil, Water, and Climate, University of Minnesota, Saint Paul, Minnesota 55108, United States
  • 2Department of Earth System Science, Stanford University, Palo Alto, California 94305, United States
  • 3Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, United States
  • 4Department of Atmospheric Sciences, University of Washington, Seattle, Washington 98195, United States
  • 5Earth Science Group, SRON Netherlands Institute for Space Research, Leiden, the Netherlands
  • 6Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, United States
  • 7Center for Global Change Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States

Abstract. We interpret space-borne observations from the TROPOspheric Monitoring Instrument (TROPOMI) in a multi-inversion framework to characterize the 2018–2019 global methane budget. Evaluation of the inverse solutions indicates that methane sources and sinks cannot be separately resolved by methane observations alone—even with the dense TROPOMI sampling coverage. Employing remote carbon monoxide (CO) and hydroxyl radical (OH) observations as additional constraints, we infer from TROPOMI a global methane source of 587 Tg/y and sink of 571 Tg/y for our analysis period. We apply a new downscaling method to map these emissions to 0.1°×0.1° resolution, using the results to uncover key gaps in the prior methane budget. The TROPOMI data point to an underestimate of tropical wetland emissions (+13 %; 20 Tg/y), with adjustments following regional hydrology. Some simple wetland parameterizations represent these patterns as accurately as more sophisticated process-based models. Fossil fuel emissions are strongly underestimated over the Middle East (+5 Tg/y), where they have been increasing rapidly over the past decade, and over Venezuela. The TROPOMI observations reveal many fossil fuel emission hotspots missing from the prior inventory, including over Mexico, Oman, Yemen, Turkmenistan, Iran, Iraq, Libya, and Algeria. Agricultural methane sources are underestimated in India, Brazil, the California Central Valley, and Asia. More than 45 % of the global upward anthropogenic source adjustment occurs over India and southeast Asia during the summer monsoon (+8.5 Tg in Jul–Oct), likely due to rainfall-enhanced emissions from rice, manure, and landfills/sewers, which increase during this season along with the natural wetland source.

Xueying Yu et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-948', John Worden, 25 Oct 2022
  • CC1: 'Comment on egusphere-2022-948', Alba Mols, 14 Nov 2022
  • RC2: 'Comment on egusphere-2022-948', Anonymous Referee #2, 15 Nov 2022

Xueying Yu et al.

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Short summary
We combine satellite measurements with a novel downscaling method to map global methane emissions at 0.1°×0.1° resolution. These fine-scale emission estimates reveal unreported emission hotspots and shed light on the roles of agriculture, wetlands, and fossil fuels for regional methane budgets. The satellite-derived emissions point in particular to missing fossil fuel emissions in the Middle East and to a large emission underestimate in South Asia that appears to be tied to monsoon rainfall.