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Volume 15, issue 9 | Copyright

Special issue: Changing Permafrost in the Arctic and its Global Effects in...

Biogeosciences, 15, 2691-2722, 2018
https://doi.org/10.5194/bg-15-2691-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 04 May 2018

Research article | 04 May 2018

Year-round simulated methane emissions from a permafrost ecosystem in Northeast Siberia

Karel Castro-Morales1, Thomas Kleinen2, Sonja Kaiser1, Sönke Zaehle1, Fanny Kittler1, Min Jung Kwon1,a, Christian Beer3,4, and Mathias Göckede1 Karel Castro-Morales et al.
  • 1Max Planck Institute for Biogeochemistry, Jena, Germany
  • 2Max Planck Institute for Meteorology, Hamburg, Germany
  • 3Department of Environmental Science and Analytical Chemistry, Stockholm University, Stockholm, Sweden
  • 4Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
  • apresent address: Korea Polar Research Institute, Incheon, Republic of Korea

Abstract. Wetlands of northern high latitudes are ecosystems highly vulnerable to climate change. Some degradation effects include soil hydrologic changes due to permafrost thaw, formation of deeper active layers, and rising topsoil temperatures that accelerate the degradation of permafrost carbon and increase in CO2 and CH4 emissions. In this work we present 2 years of modeled year-round CH4 emissions into the atmosphere from a Northeast Siberian region in the Russian Far East. We use a revisited version of the process-based JSBACH-methane model that includes four CH4 transport pathways: plant-mediated transport, ebullition and molecular diffusion in the presence or absence of snow. The gas is emitted through wetlands represented by grid cell inundated areas simulated with a TOPMODEL approach. The magnitude of the summertime modeled CH4 emissions is comparable to ground-based CH4 fluxes measured with the eddy covariance technique and flux chambers in the same area of study, whereas wintertime modeled values are underestimated by 1 order of magnitude. In an annual balance, the most important mechanism for transport of methane into the atmosphere is through plants (61%). This is followed by ebullition ( ∼ 35%), while summertime molecular diffusion is negligible (0.02%) compared to the diffusion through the snow during winter ( ∼ 4%). We investigate the relationship between temporal changes in the CH4 fluxes, soil temperature, and soil moisture content. Our results highlight the heterogeneity in CH4 emissions at landscape scale and suggest that further improvements to the representation of large-scale hydrological conditions in the model will facilitate a more process-oriented land surface scheme and better simulate CH4 emissions under climate change. This is especially necessary at regional scales in Arctic ecosystems influenced by permafrost thaw.

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We present year-round methane emissions from wetlands in Northeast Siberia that were simulated with a land surface model. Ground-based flux measurements from the same area were used for evaluation of the model results, finding a best agreement with the observations in the summertime emissions that take place in this region predominantly through plants. During winter, methane emissions through the snow contribute 4 % of the total annual methane budget, but these are still underestimated.
We present year-round methane emissions from wetlands in Northeast Siberia that were simulated...
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