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Title: Observationally derived rise in methane surface forcing mediated by water vapour trends

Abstract

Atmospheric methane (CH 4) mixing ratios exhibited a plateau between 1995 and 2006 and have subsequently been increasing. While there are a number of competing explanations for the temporal evolution of this greenhouse gas, these prominent features in the temporal trajectory of atmospheric CH 4 are expected to perturb the surface energy balance through radiative forcing, largely due to the infrared radiative absorption features of CH 4. However, to date this has been determined strictly through radiative transfer calculations. Here, we present a quantified observation of the time series of clear-sky radiative forcing by CH 4 at the surface from 2002 to 2012 at a single site derived from spectroscopic measurements along with line-by-line calculations using ancillary data. There was no significant trend in CH 4 forcing between 2002 and 2006, but since then, the trend in forcing was 0.026 ± 0.006 (99.7% CI)W m 2yr -1. The seasonal-cycle amplitude and secular trends in observed forcing are influenced by a corresponding seasonal cycle and trend in atmospheric CH 4. However, we find that we must account for the overlapping absorption effects of atmospheric water vapour (H 2O) and CH 4 to explain the observations fully. Thus, the determination of CHmore » 4 radiative forcing requires accurate observations of both the spatiotemporal distribution of CH 4 and the vertically resolved trends in H 2O.« less

Authors:
ORCiD logo [1]; ORCiD logo [2];  [1];  [1]; ORCiD logo [3];  [4];  [1];  [5];  [6];  [7];  [8];  [2]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
  3. National Oceanic and Atmospheric Administration (NOAA), Boulder, CO (United States)
  4. Univ. of Wisconsin, Madison, WI (United States)
  5. Univ. of Colorado, Boulder, CO (United States)
  6. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  7. Atmospheric and Envrionmental Research, Lexington, KY (United States)
  8. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1532308
Alternate Identifier(s):
OSTI ID: 1458639; OSTI ID: 1490275
Report Number(s):
LLNL-JRNL-741331
Journal ID: ISSN 1752-0894; 895796
Grant/Contract Number:  
AC52-07NA27344; AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
Nature Geoscience
Additional Journal Information:
Journal Volume: 11; Journal Issue: 4; Journal ID: ISSN 1752-0894
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

Feldman, D. R., Collins, W. D., Biraud, S. C., Risser, M. D., Turner, D. D., Gero, P. J., Tadic, J., Helmig, D., Xie, S., Mlawer, E. J., Shippert, T. R., and Torn, M. S. Observationally derived rise in methane surface forcing mediated by water vapour trends. United States: N. p., 2018. Web. doi:10.1038/s41561-018-0085-9.
Feldman, D. R., Collins, W. D., Biraud, S. C., Risser, M. D., Turner, D. D., Gero, P. J., Tadic, J., Helmig, D., Xie, S., Mlawer, E. J., Shippert, T. R., & Torn, M. S. Observationally derived rise in methane surface forcing mediated by water vapour trends. United States. doi:10.1038/s41561-018-0085-9.
Feldman, D. R., Collins, W. D., Biraud, S. C., Risser, M. D., Turner, D. D., Gero, P. J., Tadic, J., Helmig, D., Xie, S., Mlawer, E. J., Shippert, T. R., and Torn, M. S. Mon . "Observationally derived rise in methane surface forcing mediated by water vapour trends". United States. doi:10.1038/s41561-018-0085-9. https://www.osti.gov/servlets/purl/1532308.
@article{osti_1532308,
title = {Observationally derived rise in methane surface forcing mediated by water vapour trends},
author = {Feldman, D. R. and Collins, W. D. and Biraud, S. C. and Risser, M. D. and Turner, D. D. and Gero, P. J. and Tadic, J. and Helmig, D. and Xie, S. and Mlawer, E. J. and Shippert, T. R. and Torn, M. S.},
abstractNote = {Atmospheric methane (CH4) mixing ratios exhibited a plateau between 1995 and 2006 and have subsequently been increasing. While there are a number of competing explanations for the temporal evolution of this greenhouse gas, these prominent features in the temporal trajectory of atmospheric CH4 are expected to perturb the surface energy balance through radiative forcing, largely due to the infrared radiative absorption features of CH4. However, to date this has been determined strictly through radiative transfer calculations. Here, we present a quantified observation of the time series of clear-sky radiative forcing by CH4 at the surface from 2002 to 2012 at a single site derived from spectroscopic measurements along with line-by-line calculations using ancillary data. There was no significant trend in CH4 forcing between 2002 and 2006, but since then, the trend in forcing was 0.026 ± 0.006 (99.7% CI)W m2yr-1. The seasonal-cycle amplitude and secular trends in observed forcing are influenced by a corresponding seasonal cycle and trend in atmospheric CH4. However, we find that we must account for the overlapping absorption effects of atmospheric water vapour (H2O) and CH4 to explain the observations fully. Thus, the determination of CH4 radiative forcing requires accurate observations of both the spatiotemporal distribution of CH4 and the vertically resolved trends in H2O.},
doi = {10.1038/s41561-018-0085-9},
journal = {Nature Geoscience},
number = 4,
volume = 11,
place = {United States},
year = {2018},
month = {4}
}

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Works referenced in this record:

The HITRAN 2008 molecular spectroscopic database
journal, June 2009

  • Rothman, L. S.; Gordon, I. E.; Barbe, A.
  • Journal of Quantitative Spectroscopy and Radiative Transfer, Vol. 110, Issue 9-10, p. 533-572
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The HITRAN2012 molecular spectroscopic database
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  • Rothman, L. S.; Gordon, I. E.; Babikov, Y.
  • Journal of Quantitative Spectroscopy and Radiative Transfer, Vol. 130, p. 4-50
  • DOI: 10.1016/j.jqsrt.2013.07.002