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Title: HIMMELI v1.0: HelsinkI Model of MEthane buiLd-up and emIssion for peatlands

Wetlands are one of the most significant natural sources of methane (CH 4) to the atmosphere. They emit CH 4 because decomposition of soil organic matter in waterlogged anoxic conditions produces CH 4, in addition to carbon dioxide (CO 2). Production of CH 4 and how much of it escapes to the atmosphere depend on a multitude of environmental drivers. Models simulating the processes leading to CH 4 emissions are thus needed for upscaling observations to estimate present CH 4 emissions and for producing scenarios of future atmospheric CH 4 concentrations. Aiming at a CH 4 model that can be added to models describing peatland carbon cycling, we composed a model called HIMMELI that describes CH 4 build-up in and emissions from peatland soils. It is not a full peatland carbon cycle model but it requires the rate of anoxic soil respiration as input. Driven by soil temperature, leaf area index (LAI) of aerenchymatous peatland vegetation, and water table depth (WTD), it simulates the concentrations and transport of CH 4, CO 2, and oxygen (O 2) in a layered one-dimensional peat column. Here, we present the HIMMELI model structure and results of tests on the model sensitivity to the inputmore » data and to the description of the peat column (peat depth and layer thickness), and demonstrate that HIMMELI outputs realistic fluxes by comparing modeled and measured fluxes at two peatland sites. As HIMMELI describes only the CH 4-related processes, not the full carbon cycle, our analysis revealed mechanisms and dependencies that may remain hidden when testing CH 4 models connected to complete peatland carbon models, which is usually the case. Our results indicated that (1) the model is flexible and robust and thus suitable for different environments; (2) the simulated CH 4 emissions largely depend on the prescribed rate of anoxic respiration; (3) the sensitivity of the total CH 4 emission to other input variables is mainly mediated via the concentrations of dissolved gases, in particular, the O 2 concentrations that affect the CH 4 production and oxidation rates; (4) with given input respiration, the peat column description does not significantly affect the simulated CH 4 emissions in this model version.« less
Authors:
 [1] ; ORCiD logo [2] ;  [3] ;  [4] ; ORCiD logo [3] ;  [3] ; ORCiD logo [3] ; ORCiD logo [5] ; ORCiD logo [1] ;  [3] ; ORCiD logo [3] ;  [1] ;  [1] ;  [6] ;  [1] ;  [7] ;  [8] ;  [9] ;  [10] ;  [10] more »;  [1] « less
  1. Univ. of Helsinki (Finland)
  2. Univ. of Helsinki (Finland); Princeton Univ., NJ (United States)
  3. Finnish Meteorological Inst. (FMI), Helsinki (Finland)
  4. Finnish Meteorological Inst. (FMI), Helsinki (Finland); Lappeenranta Univ. of Technology (Finland)
  5. Lund Univ. (Sweden)
  6. Natural Resources Inst. Finland, Helsinki (Finland)
  7. Univ. of Eastern Finland, Kuopio (Finland)
  8. Univ. of Helsinki (Finland); Max Planck Society, Jena (Germany). Max Planck Inst. for Biogeochemistry
  9. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  10. Max Planck Inst. for Meteorology, Hamburg (Germany)
Publication Date:
Report Number(s):
LA-UR-17-22271
Journal ID: ISSN 1991-9603
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Geoscientific Model Development (Online)
Additional Journal Information:
Journal Name: Geoscientific Model Development (Online); Journal Volume: 10; Journal Issue: 12; Journal ID: ISSN 1991-9603
Publisher:
European Geosciences Union
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Earth Sciences; Methane emission, peatland, dynamic vegetation
OSTI Identifier:
1417159