Skip to Main Content
Error characterization of methane fluxes and budgets derived from a long-term comparison of open- and closed-path eddy covariance systemsAuthor(s): M. Julian Deventer; Timothy J. Griffis; D. Tyler Roman; Randall K. Kolka; Jeffrey D. Wood; Matt Erickson; John M. Baker; Dylan B. Millet
Source: Agricultural and Forest Meteorology
Publication Series: Scientific Journal (JRNL)
Station: Northern Research Station
Download Publication (5.0 MB)
DescriptionWetlands represent the dominant natural source of methane (CH4) to the atmosphere. Thus, substantial effort has been spent examining the CH4 budgets of global wetlands via continuous ecosystem-scale measurements using the eddy covariance (EC) technique. Robust error characterization for such measurements, however, remains a major challenge. Here, we quantify systematic, random and gap-filling errors and the resulting uncertainty in CH4 fluxes using a 3.5 year time series of simultaneous open- and closed path CH4 flux measurements over a sub-boreal wetland. After correcting for high- and low frequency flux attenuation, the magnitude of systematic frequency response errors were negligible relative to other uncertainties. Based on three different random flux error estimations, we found that errors of the CH4 flux measurement systems were smaller in magnitude than errors associated with the turbulent transport and flux footprint heterogeneity. Errors on individual half-hourly CH4 fluxes were typically 6%–41%, but not normally distributed (leptokurtic), and thus need to be appropriately characterized when fluxes are compared to chamber-derived or modeled CH4 fluxes. Integrated annual fluxes were only moderately sensitive to gap-filling, based on an evaluation of 4 different methods. Calculated budgets agreed on average to within 7% (≤1.5 g−CH4m−2 yr−1). Marginal distribution sampling using open source code was among the best-performing of all the evaluated gap-filling approaches and it is therefore recommended given its transparency and reproducibility. Overall, estimates of annual CH4 emissions for both EC systems were in excellent agreement (within 0.6 g−CH4m−2 yr−1) and averaged 18 g−CH4m−2 yr−1. Total uncertainties on the annual fluxes were larger than the uncertainty of the flux measurement systems and estimated between 7–17%. Identifying trends and differences among sites or site years requires that the observed variability exceeds these uncertainties.
- Check the Northern Research Station web site to request a printed copy of this publication.
- Our on-line publications are scanned and captured using Adobe Acrobat.
- During the capture process some typographical errors may occur.
- Please contact Sharon Hobrla, email@example.com if you notice any errors which make this publication unusable.
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
CitationDeventer, M. Julian; Griffis, Timothy J.; Roman, D. Tyler; Kolka, Randall K.; Wood, Jeffrey D.; Erickson, Matt; Baker, John M.; Millet, Dylan B. 2019. Error characterization of methane fluxes and budgets derived from a long-term comparison of open- and closed-path eddy covariance systems. Agricultural and Forest Meteorology. 278: 107638. 15 p. https://doi.org/10.1016/j.agrformet.2019.107638.
KeywordsEddy covariance, Methane, Uncertainty, Error, Budget
- FLUXNET-CH4 Synthesis Activity: Objectives, Observations, and Future Directions
- Biases in open-path carbon dioxide flux measurements: Roles of instrument surface heat exchange and analyzer temperature sensitivity
- Source partitioning of methane emissions and its seasonality in the U.S. Midwest
XML: View XML