Simulating net ecosystem exchange under seasonal snow cover at an Arctic tundra site

Dutch, Victoria R. ORCID:, Rutter, Nick, Wake, Leanne, Sonnentag, Oliver, Hould Gosselin, Gabriel, Sandells, Melody, Derksen, Chris, Walker, Branden, Meyer, Gesa, Essery, Richard, Kelly, Richard, Marsh, Phillip, Boike, Julia and Detto, Matteo (2024) Simulating net ecosystem exchange under seasonal snow cover at an Arctic tundra site. Biogeosciences, 21 (3). pp. 825-841. ISSN 1726-4189

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Estimates of winter (snow-covered non-growing season) CO2 fluxes across the Arctic region vary by a factor of 3.5, with considerable variation between measured and simulated fluxes. Measurements of snow properties, soil temperatures, and net ecosystem exchange (NEE) at Trail Valley Creek, NWT, Canada, allowed for the evaluation of simulated winter NEE in a tundra environment with the Community Land Model (CLM5.0). Default CLM5.0 parameterisations did not adequately simulate winter NEE in this tundra environment, with near-zero NEE (< 0.01 ) simulated between November and mid-May. In contrast, measured NEE was broadly positive (indicating net CO2 release) from snow-cover onset until late April. Changes to the parameterisation of snow thermal conductivity, required to correct for a cold soil temperature bias, reduced the duration for which no NEE was simulated. Parameter sensitivity analysis revealed the critical role of the minimum soil moisture threshold of decomposition (Ψmin) in regulating winter soil respiration. The default value of this parameter (Ψmin) was too high, preventing simulation of soil respiration for the vast majority of the snow-covered season. In addition, the default rate of change of soil respiration with temperature (Q10) was too low, further contributing to poor model performance during winter. As Ψmin and Q10 had opposing effects on the magnitude of simulated winter soil respiration, larger negative values of Ψmin and larger positive values of Q10 are required to simulate wintertime NEE more adequately.

Item Type: Article
Additional Information: Funding Information: This research has been supported by the Natural Environment Research Council (Carbon Emissions under Arctic Snow – grant no. NE/W003686/1). Funding Information: Victoria R. Dutch was funded by an RDF Studentship from Northumbria University and the Northern Water Futures project. The eddy covariance and supporting measurements at Trail Valley Creek were funded through the Canada Foundation for Innovation, the Canada Research Chairs Program, and a Natural Sciences and Engineering Research Council of Canada Discovery Grant awarded to Oliver Sonnentag and Phillip Marsh. Publisher Copyright: © 2024 Copernicus Publications. All rights reserved.
Uncontrolled Keywords: earth-surface processes,ecology, evolution, behavior and systematics,sdg 15 - life on land ,/dk/atira/pure/subjectarea/asjc/1900/1904
Faculty \ School: Faculty of Science > School of Environmental Sciences
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Depositing User: LivePure Connector
Date Deposited: 04 Mar 2024 18:33
Last Modified: 12 Mar 2024 09:37
DOI: 10.5194/bg-21-825-2024


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