Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
doi:10.5194/acp-2017-72
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
21 Feb 2017
Review status
This discussion paper is under review for the journal Atmospheric Chemistry and Physics (ACP).
Estimating regional scale methane flux and budgets using CARVE aircraft measurements over Alaska
Sean Hartery1, Róisín Commane2, Jakob Lindaas2, Colm Sweeney3,4, John Henderson5, Marikate Mountain5, Nicholas Steiner6, Kyle McDonald6, Steven J. Dinardo7, Charles E. Miller7, Steven C. Wofsy2, and Rachel Y.-W. Chang1,2 1Department of Physics and Atmospheric Science, Dalhousie University, Halifax NS
2School of Engineering and Applied Sciences, Harvard University, Cambridge MA
3Global Monitoring Division, National Oceanic and Atmospheric Administration Earth System Research Laboratory, Boulder CO
4Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder CO
5Atmospheric and Environmental Research, Inc., Lexington, MA
6Department of Earth and Atmospheric Science, City College University of New York, New York NY
7Jet Propulsion Laboratory, California Institute of Technology, Pasadena CA
Abstract. Methane (CH4) is the second most important greenhouse gas but its emissions from northern regions is still poorly constrained. In this study, we analyze a subset of in situ CH4 aircraft observations made over Alaska during the growing seasons of 2012–2014 as part of the Carbon in Arctic Reservoir Vulnerability Experiment (CARVE). Surface CH4 fluxes are estimated using an atmospheric particle transport model which quantitatively links surface emissions from Alaska and the western Yukon with observations of enhanced CH4 in the boundary layer. We estimate that between May and September, 2.1 ± 0.5 Tg, 1.7 ± 0.4 Tg and 2.0 ± 0.3 Tg of CH4 were emitted from the region of interest for 2012–2014, respectively. The predominant sources of the CH4 budget were two broadly classed eco-regions within our domain, with CH4 from the tundra region accounting for over half of the overall budget, despite only representing 18 % of the total surface area. Boreal regions, which cover a large part of the study region, accounted for the remainder of the emissions. Simple multiple linear regression analysis revealed that overall, CH4 flux were largely driven by soil temperature and elevation. In regions specifically dominated by wetlands, soil temperature and moisture at 10 cm depth were important explanatory variables while in regions that were not wetlands, soil temperature and moisture at 40 cm depth were more important, reflecting the depth at which methanogenesis occurs. Although similar variables have been found in the past to control CH4 emissions at local scales, this study shows that they can be used to generate a statistical model to estimate the regional scale CH4 budget.

Citation: Hartery, S., Commane, R., Lindaas, J., Sweeney, C., Henderson, J., Mountain, M., Steiner, N., McDonald, K., Dinardo, S. J., Miller, C. E., Wofsy, S. C., and Chang, R. Y.-W.: Estimating regional scale methane flux and budgets using CARVE aircraft measurements over Alaska, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-72, in review, 2017.
Sean Hartery et al.
Sean Hartery et al.
Sean Hartery et al.

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Short summary
Methane is the 2nd most important greenhouse gas but its emissions from northern regions is still poorly constrained. This study uses aircraft measurements of methane from Alaska to estimate surface emissions. We found that methane emission rates depend on the soil temperature at depths where its production was taking place, and that total emissions were similar between tundra and boreal regions. These results provide a simple way to predict methane emissions in this region.
Methane is the 2nd most important greenhouse gas but its emissions from northern regions is...
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