Characterizing Performance of Freshwater Wetland Methane Models Across Time Scales at FLUXNET-CH₄ Sites Using Wavelet Analyses

Abstract

Process-based land surface models are important tools for estimating global wetland methane (CH₄) emissions and projecting their behavior across space and time. So far there are no performance assessments of model responses to drivers at multiple time scales. In this study, we apply wavelet analysis to identify the dominant time scales contributing to model uncertainty in the frequency domain. We evaluate seven wetland models at 23 eddy covariance tower sites. Our study first characterizes site-level patterns of freshwater wetland CH₄ fluxes (FCH₄) at different time scales. A Monte Carlo approach was developed to incorporate flux observation error to avoid misidentification of the time scales that dominate model error. Our results suggest that (a) significant model-observation disagreements are mainly at multi-day time scales (<15 days); (b) most of the models can capture the CH₄ variability at monthly and seasonal time scales (>32 days) for the boreal and Arctic tundra wetland sites but have significant bias in variability at seasonal time scales for temperate and tropical/subtropical sites; (c) model errors exhibit increasing power spectrum as time scale increases, indicating that biases at time scales <5 days could contribute to persistent systematic biases on longer time scales; and (d) differences in error pattern are related to model structure (e.g., proxy of CH₄ production). Our evaluation suggests the need to accurately replicate FCH₄ variability, especially at short time scales, in future wetland CH₄ model developments.

• author: Zhang, Zhen ; Bansal, Sheel ; Chang, Kuang Yu ; Fluet-Chouinard, Etienne ; Delwiche, Kyle ; Goeckede, Mathias ; Gustafson, Adrian ; Knox, Sara ; Leppänen, Antti ; Liu, Licheng ; Liu, Jinxun ; Malhotra, Avni ; Markkanen, Tiina ; McNicol, Gavin ; Melton, Joe R. ; Miller, Paul A. ; Peng, Changhui ; Raivonen, Maarit ; Riley, William J. ; Sonnentag, Oliver ; Aalto, Tuula ; Vargas, Rodrigo ; Zhang, Wenxin ; Zhu, Qing ; Zhu, Qiuan ; Zhuang, Qianlai ; Windham-Myers, Lisamarie ; Jackson, Robert B. and Poulter, Benjamin
• organization: Dept of Physical Geography and Ecosystem Science; LU Profile Area: Nature-based future solutions; LTH Profile Area: Aerosols; eSSENCE: The e-Science Collaboration; Centre for Environmental and Climate Science (CEC); BECC: Biodiversity and Ecosystem services in a Changing Climate; MERGE: ModElling the Regional and Global Earth system
• publishing date: 2023-11
• type: Contribution to journal
• publication status: published
• subject: Environmental Sciences; Climate Research; Natural Sciences
• keywords: Methane, Biogeochemical models, wavelet analysis, LPJ-GUESS
• in: Journal of Geophysical Research: Biogeosciences
• volume: 128
• issue: 11
• article number: e2022JG007259
• publisher: Wiley
• external identifiers: scopus:85176099332
• ISSN: 2169-8953
• DOI: 10.1029/2022JG007259
• language: English
• LU publication?: yes
• additional info: Funding Information: We acknowledge primary support from the Gordon and Betty Moore Foundation (Grant GBMF5439) and from the John Wesley Powell Center for Analysis and Synthesis of the U.S. Geological Survey (“Wetland FLUXNET Synthesis for Methane”). W.J.R., Q.Z, and K.Y.C were supported by the Reducing Uncertainties in Biogeochemical Interactions through Synthesis and Computation (RUBISCO) Scientific Focus Area which is sponsored by the Earth and Environmental Systems Modeling (EESM) Program under the Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science to Lawrence Berkeley National Laboratory (LBNL) under Contract DEAC02-05CH11231. O.S. acknowledges funding by the Canada Research Chairs, Canada Foundation for Innovation Leaders Opportunity Fund, and Natural Sciences and Engineering Research Council Discovery Grant Programs. SB was funded by the U.S. Geological Survey, Ecosystem Mission Area, Land Change Science Climate R&D Program and U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research, Grant DE-SC0023084. W.Z. acknowledged the support by the Swedish Research Council (Vetenskapsrådet) start Grant (2020-05338). Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Funding Information: We acknowledge primary support from the Gordon and Betty Moore Foundation (Grant GBMF5439) and from the John Wesley Powell Center for Analysis and Synthesis of the U.S. Geological Survey (“Wetland FLUXNET Synthesis for Methane”). W.J.R., Q.Z, and K.Y.C were supported by the Reducing Uncertainties in Biogeochemical Interactions through Synthesis and Computation (RUBISCO) Scientific Focus Area which is sponsored by the Earth and Environmental Systems Modeling (EESM) Program under the Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science to Lawrence Berkeley National Laboratory (LBNL) under Contract DEAC02‐05CH11231. O.S. acknowledges funding by the Canada Research Chairs, Canada Foundation for Innovation Leaders Opportunity Fund, and Natural Sciences and Engineering Research Council Discovery Grant Programs. SB was funded by the U.S. Geological Survey, Ecosystem Mission Area, Land Change Science Climate R&D Program and U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research, Grant DE‐SC0023084. W.Z. acknowledged the support by the Swedish Research Council (Vetenskapsrådet) start Grant (2020‐05338). Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Publisher Copyright: © 2023. The Authors.
• id: e080e147-a8d8-49b8-987b-2276f4ddf7f1
• date added to LUP: 2023-11-17 09:19:22
• date last changed: 2024-02-06 23:10:59