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Top-down estimate of methane emissions in California using a mesoscale inverse modeling technique [electronic resource] : The South Coast Air Basin

Published:
Washington, D.C. : United States. National Nuclear Security Administration, 2015.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
Physical Description:
pages 6,698-6,711 : digital, PDF file
Additional Creators:
Sandia National Laboratories, United States. National Nuclear Security Administration, and United States. Department of Energy. Office of Scientific and Technical Information
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Summary:
Methane (CH4) is the primary component of natural gas and has a larger global warming potential than CO2. Some recent top-down studies based on observations showed CH4 emissions in California's South Coast Air Basin (SoCAB) were greater than those expected from population-apportioned bottom-up state inventories. In this study, we quantify CH4 emissions with an advanced mesoscale inverse modeling system at a resolution of 8 km × 8 km, using aircraft measurements in the SoCAB during the 2010 Nexus of Air Quality and Climate Change campaign to constrain the inversion. To simulate atmospheric transport, we use the FLEXible PARTicle-Weather Research and Forecasting (FLEXPART-WRF) Lagrangian particle dispersion model driven by three configurations of the Weather Research and Forecasting (WRF) mesoscale model. We determine surface fluxes of CH4 using a Bayesian least squares method in a four-dimensional inversion. Simulated CH4 concentrations with the posterior emission inventory achieve much better correlations with the measurements (R2 = 0.7) than using the prior inventory (U.S. Environmental Protection Agency's National Emission Inventory 2005, R2 = 0.5). The emission estimates for CH4 in the posterior, 46.3 ± 9.2 Mg CH4/h, are consistent with published observation-based estimates. Changes in the spatial distribution of CH4 emissions in the SoCAB between the prior and posterior inventories are discussed. Missing or underestimated emissions from dairies, the oil/gas system, and landfills in the SoCAB seem to explain the differences between the prior and posterior inventories. Furthermore, we estimate that dairies contributed 5.9 ± 1.7 Mg CH4/h and the two sectors of oil and gas industries (production and downstream) and landfills together contributed 39.6 ± 8.1 Mg CH4/h in the SoCAB.
Report Numbers:
E 1.99:sand--2015-4909j
sand--2015-4909j
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Note:
Published through SciTech Connect.
07/28/2015.
"sand--2015-4909j"
"594363"
Journal of Geophysical Research: Atmospheres (Online) 120 13 ISSN 2169-8996 AM
Yu Yan Cui; Jerome Brioude; Stuart A. McKeen; Wayne M. Angevine; Si -Wan Kim; Gregory J. Frost; Ravan Ahmadov; Jeff Peischl; Nicolas Bousserez; Zhen Liu; Thomas B. Ryerson; Steve C. Wofsy; Gregory W. Santoni; Eric A. Kort; Marc L. Fischer; Michael Trainer.
Funding Information:
AC04-94AL85000
View MARC record | catkey: 23776556