HIMMELI v1.0: HelsinkI Model of MEthane buiLd-up and emIssion
Maarit Raivonen1, Sampo Smolander1,2, Leif Backman3, Jouni Susiluoto3, Tuula Aalto3, Tiina Markkanen3, Jarmo Mäkelä3, Janne Rinne4, Olli Peltola1, Mika Aurela3, Marin Tomasic1, Xuefei Li1, Tuula Larmola5, Sari Juutinen6, Eeva-Stiina Tuittila7, Martin Heimann1,8, Sanna Sevanto9, Thomas Kleinen10, Victor Brovkin10, and Timo Vesala1,111Division of Atmospheric Sciences, Department of Physics, University of Helsinki, P.O. Box 68, 00014 Helsinki, Finland 2Princeton Environmental Institute, Guyot Hall, Princeton University, Princeton, NJ 08544, USA 3Climate research, Finnish Meteorological Institute, P.O. Box 503, 00101 Helsinki, Finland 4Department of Physical Geography and Ecosystem Science, Lund University, Sölvegatan 12, 22362 Lund, Sweden 5Natural Resources Institute Finland (Luke), Latokartanonkaari 9, 00790 Helsinki, Finland 6Department of Environmental Sciences, University of Helsinki, Viikinkaari 1, 00790 Helsinki, Finland 7School of Forest Sciences, University of Eastern Finland, P.O. Box 111, 80770 Joensuu, Finland 8Max Planck Institute for Biogeochemistry, 07745 Jena, Germany 9Earth and Environmental Sciences Division, Los Alamos National Laboratory, Bikini Atoll Rd. MS J535, Los Alamos, NM 87545, USA 10Max Planck Institute for Meteorology, Bundesstr, 53, 20146, Hamburg, Germany 11Department of Forest Sciences, University of Helsinki, P.O. Box 27, 00014 Helsinki, Finland
Received: 02 Mar 2017 – Accepted for review: 22 Mar 2017 – Discussion started: 27 Mar 2017
Abstract. Wetlands are one of the most significant natural sources of methane (CH4) to the atmosphere. They emit CH4 because decomposition of soil organic matter in waterlogged anoxic conditions produces CH4, in addition to carbon dioxide (CO2). Production of CH4 and how much of it escapes to the atmosphere depend on a multitude of environmental drivers. Models simulating the processes leading to CH4 emissions are thus needed for upscaling observations to estimate present CH4 emissions and for producing scenarios of future atmospheric CH4 concentrations. Aiming at a CH4 model that can be added to models describing peatland carbon cycling, we developed a model called HIMMELI that describes CH4 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 CH4, CO2 and oxygen (O2) in a layered one-dimensional peat column. Here, we present the HIMMELI model structure, results of tests on the model sensitivity to the input data and to the description of the peat column (peat depth and layer thickness), and an intercomparison of the modelled and measured CH4 fluxes at Siikaneva, a peatland flux measurement site in Southern Finland. As HIMMELI describes only the CH4-related processes, not the full carbon cycle, our analysis revealed mechanisms and dependencies that may remain hidden when testing CH4 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 CH4 emissions largely depend on the prescribed rate of anoxic respiration; 3) the sensitivity of the total CH4 emission to other input variables, LAI and WTD, is mainly mediated via the O2 concentrations that affect the CH4 production and oxidation rates; 4) with given input respiration, the peat column description does not affect significantly the simulated CH4 emissions.
Raivonen, M., Smolander, S., Backman, L., Susiluoto, J., Aalto, T., Markkanen, T., Mäkelä, J., Rinne, J., Peltola, O., Aurela, M., Tomasic, M., Li, X., Larmola, T., Juutinen, S., Tuittila, E.-S., Heimann, M., Sevanto, S., Kleinen, T., Brovkin, V., and Vesala, T.: HIMMELI v1.0: HelsinkI Model of MEthane buiLd-up and emIssion
for peatlands, Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-52, in review, 2017.