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Interpreting the seasonality of atmospheric methane
  • +12
  • James D. East,
  • Daniel J. Jacob,
  • Nicholas Balasus,
  • A. Anthony Bloom,
  • Lori P. Bruhwiler,
  • Zichong Chen,
  • Jed O. Kaplan,
  • Loretta J Mickley,
  • Todd A. Mooring,
  • Elise Penn,
  • Benjamin Poulter,
  • Melissa Payer Sulprizio,
  • Robert M. Yantosca,
  • John R. Worden,
  • Zhen Zhang
James D. East
Harvard John A. Paulson School of Engineering and Applied Sciences

Corresponding Author:[email protected]

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Daniel J. Jacob
Harvard John A. Paulson School of Engineering and Applied Sciences
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Nicholas Balasus
Harvard John A. Paulson School of Engineering and Applied Sciences
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A. Anthony Bloom
Jet Propulsion Laboratory, California Institute of Technology
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Lori P. Bruhwiler
National Oceanic and Atmospheric Administration (NOAA)
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Zichong Chen
Harvard John A. Paulson School of Engineering and Applied Sciences
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Jed O. Kaplan
Department of Earth, Energy, and Environment, University of Calgary
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Loretta J Mickley
Harvard John A. Paulson School of Engineering and Applied Sciences
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Todd A. Mooring
Department of Earth and Planetary Sciences, Harvard University
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Elise Penn
Department of Earth and Planetary Sciences, Harvard University
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Benjamin Poulter
NASA GSFC, Biospheric Sciences Lab
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Melissa Payer Sulprizio
Harvard John A. Paulson School of Engineering and Applied Sciences
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Robert M. Yantosca
Harvard John A. Paulson School of Engineering and Applied Sciences
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John R. Worden
Jet Propulsion Laboratory, California Institute of Technology
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Zhen Zhang
State Key Laboratory of Tibetan Plateau Earth System, Environment and Resources (TPESER), Institute of Tibetan Plateau Research, Chinese Academy of Sciences
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Abstract

Surface and satellite observations of atmospheric methane show smooth seasonal behavior in the Southern Hemisphere driven by loss from the hydroxyl (OH) radical. However, observations in the Northern Hemisphere show a sharp mid-summer increase that is asymmetric with the Southern Hemisphere and not captured by the default configuration of the GEOS-Chem chemical transport model. Using an ensemble of 22 OH model estimates and 24 wetland emission inventories in GEOS-Chem, we show that the magnitude, latitudinal distribution, and seasonality of Northern Hemisphere wetland emissions are critical for reproducing the observed seasonality of methane in that hemisphere, with the interhemispheric OH ratio playing a lesser role. Reproducing the observed seasonality requires a wetland emission inventory with ~80 Tg a-1 poleward of 10°N including significant emissions in South Asia, and an August peak in boreal emissions persisting into autumn. In our 24-member wetland emission ensemble, only the LPJ-wsl MERRA-2 inventory has these attributes.
31 Jan 2024Submitted to ESS Open Archive
02 Feb 2024Published in ESS Open Archive
28 May 2024Published in Geophysical Research Letters volume 51 issue 10. 10.1029/2024GL108494