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A New Process-Based Soil Methane Scheme : Evaluation Over Arctic Field Sites With the ISBA Land Surface Model

Morel, X.; Decharme, B.; Delire, C.; Krinner, G.; Lund, M. LU ; Hansen, B. U. LU and Mastepanov, M. LU (2019) In Journal of Advances in Modeling Earth Systems 11(1). p.293-326
Abstract

Permafrost soils and arctic wetlands methane emissions represent an important challenge for modeling the future climate. Here we present a process-based model designed to correctly represent the main thermal, hydrological, and biogeochemical processes related to these emissions for general land surface modeling. We propose a new multilayer soil carbon and gas module within the Interaction Soil-Biosphere-Atmosphere (ISBA) land-surface model (LSM). This module represents carbon pools, vertical carbon dynamics, and both oxic and anoxic organic matter decomposition. It also represents the soil gas processes for CH4, CO2, and O2 through the soil column. We base CH4 production and oxydation on an... (More)

Permafrost soils and arctic wetlands methane emissions represent an important challenge for modeling the future climate. Here we present a process-based model designed to correctly represent the main thermal, hydrological, and biogeochemical processes related to these emissions for general land surface modeling. We propose a new multilayer soil carbon and gas module within the Interaction Soil-Biosphere-Atmosphere (ISBA) land-surface model (LSM). This module represents carbon pools, vertical carbon dynamics, and both oxic and anoxic organic matter decomposition. It also represents the soil gas processes for CH4, CO2, and O2 through the soil column. We base CH4 production and oxydation on an O2 control instead of the classical water table level strata approach used in state-of-the-art soil CH4 models. We propose a new parametrization of CH4 oxydation using recent field experiments and use an explicit O2 limitation for soil carbon decomposition. Soil gas transport is computed explicitly, using a revisited formulation of plant-mediated transport, a new representation of gas bulk diffusivity in porous media closer to experimental observations, and an innovative advection term for ebullition. We evaluate this advanced model on three climatically distinct sites : two in Greenland (Nuuk and Zackenberg) and one in Siberia (Chokurdakh). The model realistically reproduces methane and carbon dioxide emissions from both permafrosted and nonpermafrosted sites. The evolution and vertical characteristics of the underground processes leading to these fluxes are consistent with current knowledge. Results also show that physics is the main driver of methane fluxes, and the main source of variability appears to be the water table depth.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
arctic ecosystem, carbon cycling, methane emission, modeling
in
Journal of Advances in Modeling Earth Systems
volume
11
issue
1
pages
293 - 326
publisher
Wiley-Blackwell
external identifiers
  • scopus:85060677750
DOI
10.1029/2018MS001329
language
English
LU publication?
yes
id
8b389f28-59e7-4eac-a886-f430af155601
date added to LUP
2019-02-07 08:31:37
date last changed
2019-05-27 15:21:40
@article{8b389f28-59e7-4eac-a886-f430af155601,
  abstract     = {<p>Permafrost soils and arctic wetlands methane emissions represent an important challenge for modeling the future climate. Here we present a process-based model designed to correctly represent the main thermal, hydrological, and biogeochemical processes related to these emissions for general land surface modeling. We propose a new multilayer soil carbon and gas module within the Interaction Soil-Biosphere-Atmosphere (ISBA) land-surface model (LSM). This module represents carbon pools, vertical carbon dynamics, and both oxic and anoxic organic matter decomposition. It also represents the soil gas processes for CH<sub>4</sub>, CO<sub>2</sub>, and O<sub>2</sub> through the soil column. We base CH<sub>4</sub> production and oxydation on an O<sub>2</sub> control instead of the classical water table level strata approach used in state-of-the-art soil CH<sub>4</sub> models. We propose a new parametrization of CH<sub>4</sub> oxydation using recent field experiments and use an explicit O<sub>2</sub> limitation for soil carbon decomposition. Soil gas transport is computed explicitly, using a revisited formulation of plant-mediated transport, a new representation of gas bulk diffusivity in porous media closer to experimental observations, and an innovative advection term for ebullition. We evaluate this advanced model on three climatically distinct sites : two in Greenland (Nuuk and Zackenberg) and one in Siberia (Chokurdakh). The model realistically reproduces methane and carbon dioxide emissions from both permafrosted and nonpermafrosted sites. The evolution and vertical characteristics of the underground processes leading to these fluxes are consistent with current knowledge. Results also show that physics is the main driver of methane fluxes, and the main source of variability appears to be the water table depth.</p>},
  author       = {Morel, X. and Decharme, B. and Delire, C. and Krinner, G. and Lund, M. and Hansen, B. U. and Mastepanov, M.},
  keyword      = {arctic ecosystem,carbon cycling,methane emission,modeling},
  language     = {eng},
  number       = {1},
  pages        = {293--326},
  publisher    = {Wiley-Blackwell},
  series       = {Journal of Advances in Modeling Earth Systems},
  title        = {A New Process-Based Soil Methane Scheme : Evaluation Over Arctic Field Sites With the ISBA Land Surface Model},
  url          = {http://dx.doi.org/10.1029/2018MS001329},
  volume       = {11},
  year         = {2019},
}