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| Titel |
Seasonal and interannual variability in wetland methane emissions simulated by CLM4Me' and CAM-chem and comparisons to observations of concentrations |
| VerfasserIn |
L. Meng, R. Paudel, P. G. M. Hess, N. M. Mahowald |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 13 ; Nr. 12, no. 13 (2015-07-03), S.4029-4049 |
| Datensatznummer |
250118011
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| Publikation (Nr.) |
 copernicus.org/bg-12-4029-2015.pdf |
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| Zusammenfassung |
| Understanding the temporal and spatial variation of wetland methane emissions
is essential to the estimation of the global methane budget. Our goal for
this study is three-fold: (i) to evaluate the wetland methane fluxes
simulated in two versions of the Community Land Model, the Carbon-Nitrogen
(CN; i.e., CLM4.0) and the Biogeochemistry (BGC; i.e., CLM4.5) versions using
the methane emission model CLM4Me' so as to determine the
sensitivity of the emissions to the underlying carbon model; (ii) to compare
the simulated atmospheric methane concentrations to observations, including
latitudinal gradients and interannual variability so as to determine the
extent to which the atmospheric observations constrain the emissions; (iii)
to understand the drivers of seasonal and interannual variability in
atmospheric methane concentrations. Simulations of the transport and removal
of methane use the Community Atmosphere Model with chemistry (CAM-chem) model in conjunction
with CLM4Me' methane emissions from both CN and BGC simulations and
other methane emission sources from literature. In each case we compare model-simulated atmospheric methane concentration with observations. In addition,
we simulate the atmospheric concentrations based on the TransCom wetland and
rice paddy emissions derived from a different terrestrial ecosystem model,
Vegetation Integrative Simulator for Trace gases (VISIT). Our analysis indicates CN wetland methane emissions are higher in the
tropics and lower at high latitudes than emissions from BGC. In CN, methane
emissions decrease from 1993 to 2004 while this trend does not appear in the
BGC version. In the CN version, methane emission variations follow
satellite-derived inundation wetlands closely. However, they are dissimilar
in BGC due to its different carbon cycle. CAM-chem simulations with
CLM4Me' methane emissions suggest that both prescribed anthropogenic
and predicted wetlands methane emissions contribute substantially to seasonal
and interannual variability in atmospheric methane concentration. Simulated
atmospheric CH4 concentrations in CAM-chem are highly correlated with
observations at most of the 14 measurement stations evaluated with an average
correlation between 0.71 and 0.80 depending on the simulation (for the period
of 1993–2004 for most stations based on data availability). Our results
suggest that different spatial patterns of wetland emissions can have
significant impacts on Northern and Southern hemisphere (N–S) atmospheric CH4 concentration gradients and
growth rates. This study suggests that both anthropogenic and wetland
emissions have significant contributions to seasonal and interannual
variations in atmospheric CH4 concentrations. However, our analysis also
indicates the existence of large uncertainties in terms of spatial patterns
and magnitude of global wetland methane budgets, and that substantial
uncertainty comes from the carbon model underlying the methane flux modules. |
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