Eddy covariance observations of surface leakage during shallow subsurface CO2 releases

dc.contributor.authorLewicki, Jennifer L.
dc.contributor.authorHilley, George E.
dc.contributor.authorFischer, Marc L.
dc.contributor.authorPan, Lehua
dc.contributor.authorOldenburg, Curtis M.
dc.contributor.authorDobeck, Laura M.
dc.contributor.authorSpangler, Lee H.
dc.description.abstractWe tested the ability of eddy covariance (EC) to detect, locate, and quantify surface CO2 flux leakage signals within a background ecosystem. For 10 days starting on 9 July 2007, and for 7 days starting on 3 August 2007, 0.1 (Release 1) and 0.3 (Release 2) t CO2 d−1, respectively, were released from a horizontal well ∼100 m in length and ∼2.5 m in depth located in an agricultural field in Bozeman, Montana. An EC station measured net CO2 flux (Fc) from 8 June 2006 to 4 September 2006 (mean and standard deviation = −12.4 and 28.1 g m−2 d−1, respectively) and from 28 May 2007 to 4 September 2007 (mean and standard deviation = −12.0 and 28.1 g m−2 d−1, respectively). The Release 2 leakage signal was visible in the Fc time series, whereas the Release 1 signal was difficult to detect within variability of ecosystem fluxes. To improve detection ability, we calculated residual fluxes (Fcr) by subtracting fluxes corresponding to a model for net ecosystem exchange from Fc. Fcr had reduced variability and lacked the negative bias seen in corresponding Fc distributions. Plotting the upper 90th percentile Fcr versus time enhanced the Release 2 leakage signal. However, values measured during Release 1 fell within the variability assumed to be related to unmodeled natural processes. Fcr measurements and corresponding footprint functions were inverted using a least squares approach to infer the spatial distribution of surface CO2 fluxes during Release 2. When combined with flux source area evaluation, inversion results roughly located the CO2 leak, while resolution was insufficient to quantify leakage rate.en_US
dc.description.sponsorshipU.S. Department of Energy ZERT Project contract DE‐AC02‐05CH11231en_US
dc.identifier.citationLewicki, Jennifer L., George E. Hilley, Marc L. Fischer, Lehua Pan, Curtis M. Oldenburg, Laura M. Dobeck, and Lee H. Spangler. “Eddy Covariance Observations of Surface Leakage During Shallow Subsurface CO2 releases.” Journal of Geophysical Research 114, no. D12 (June 18, 2009). doi:10.1029/2008jd011297.en_US
dc.rightsThis Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).en_US
dc.titleEddy covariance observations of surface leakage during shallow subsurface CO2 releasesen_US
mus.citation.journaltitleJournal of Geophysical Research - Atmospheresen_US
mus.contributor.orcidSpangler, Lee H.|0000-0002-3870-6696en_US
mus.identifier.categoryLife Sciences & Earth Sciencesen_US
mus.relation.collegeCollege of Letters & Scienceen_US
mus.relation.departmentChemistry & Biochemistry.en_US
mus.relation.researchgroupZero Emissions Research and Technology (ZERT).en_US
mus.relation.universityMontana State University - Bozemanen_US


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