A multitower measurement network estimate of California's methane emissions

Journal Article · Fri Sep 20 00:00:00 EDT 2013 · Journal of Geophysical Research: Atmospheres

DOI:https://doi.org/10.1002/jgrd.50854· OSTI ID:1127146

Jeong, Seongeun ^[1]; Hsu, Ying-Kuang ^[2]; Andrews, Arlyn E. ^[3]; Bianco, Laura ^[4]; Vaca, Patrick ^[2]; Wilczak, James M. ^[3]; Fischer, Marc L. ^[5]

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1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Environmental Energy Technologies Division
2. California Air Resources Board, Sacramento, CA (United States)
3. National Oceanic and Atmospheric Administration (NOAA), Boulder, CO (United States). Earth System Research Lab.
4. National Oceanic and Atmospheric Administration (NOAA), Boulder, CO (United States). Earth System Research Lab.; Univ. of Colorado, Boulder, CO (United States). Cooperative Inst. for Research in Environmental Sciences
5. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Environmental Energy Technologies Division; California State Univ. (CalState East Bay), Hayward, CA (United States). Dept. of Anthropology, Geography and Environmental Studies

In this paper, we present an analysis of methane (CH₄) emissions using atmospheric observations from five sites in California's Central Valley across different seasons (September 2010 to June 2011). CH₄ emissions for spatial regions and source sectors are estimated by comparing measured CH₄ mixing ratios with transport model (Weather Research and Forecasting and Stochastic Time-Inverted Lagrangian Transport) predictions based on two 0.1° CH₄ (seasonally varying “California-specific” (California Greenhouse Gas Emission Measurements, CALGEM) and a static global (Emission Database for Global Atmospheric Research, release version 42, EDGAR42)) prior emission models. Region-specific Bayesian analyses indicate that for California's Central Valley, the CALGEM- and EDGAR42-based inversions provide consistent annual total CH₄ emissions (32.87 ± 2.09 versus 31.60 ± 2.17 Tg CO₂eq yr^-1; 68% confidence interval (CI), assuming uncorrelated errors between regions). Summing across all regions of California, optimized CH₄ emissions are only marginally consistent between CALGEM- and EDGAR42-based inversions (48.35 ± 6.47 versus 64.97 ± 11.85 Tg CO₂eq), because emissions from coastal urban regions (where landfill and natural gas emissions are much higher in EDGAR than CALGEM) are not strongly constrained by the measurements. Combining our results with those from a recent study of the South Coast Air Basin narrows the range of estimates to 43–57 Tg CO2eq yr^-1 (1.3–1.8 times higher than the current state inventory). Finally, these results suggest that the combination of rural and urban measurements will be necessary to verify future changes in California's total CH₄ emissions.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE; National Oceanic and Atmospheric Administration (NOAA) (United States); California Air Resources Board (CARB) (United States)
• Contributing Organization: California Air Resources Board, Sacramento, CA (United States); National Oceanic and Atmospheric Administration (NOAA), Boulder, CO (United States)
• DOE Contract Number: AC02-05CH11231; 09-348
• OSTI ID: 1127146
• Report Number(s): LBNL-6561E
• Journal Information: Journal of Geophysical Research: Atmospheres, Vol. 118, Issue 19; ISSN 2169-897X
• Publisher: American Geophysical Union
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
methane
greenhouse gas
emission inventory
atmospheric transport
inverse model