Linking emissions of fossil fuel CO2 and other anthropogenic trace gases using atmospheric 14CO2

Atmospheric CO2 gradients are usually dominated by the signal from net terrestrial biological fluxes, despite the fact that fossil fuel combustion fluxes are larger in the annual mean. Here, we use a six year long series of 14CO2 and CO2 measurements obtained from vertical profiles at two northeast...

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Bibliographic Details
Published in:Journal of Geophysical Research: Atmospheres 2012-04, Vol.117 (D8), p.n/a
Main Authors: Miller, John B., Lehman, Scott J., Montzka, Stephen A., Sweeney, Colm, Miller, Benjamin R., Karion, Anna, Wolak, Chad, Dlugokencky, Ed J., Southon, John, Turnbull, Jocelyn C., Tans, Pieter P.
Format: Article
Language:English
Subjects:
carbon dioxide
Earth sciences
Earth, ocean, space
emissions
Exact sciences and technology
fossil fuel
HCFCs
HFCs
radiocarbon
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Summary:Atmospheric CO2 gradients are usually dominated by the signal from net terrestrial biological fluxes, despite the fact that fossil fuel combustion fluxes are larger in the annual mean. Here, we use a six year long series of 14CO2 and CO2 measurements obtained from vertical profiles at two northeast U.S. aircraft sampling sites to partition lower troposphere CO2 enhancements (and depletions) into terrestrial biological and fossil fuel components (Cbio and Cff). Mean Cff is 1.5 ppm, and 2.4 ppm when we consider only planetary boundary layer samples. However, we find that the contribution of Cbio to CO2 enhancements is large throughout the year, and averages 60% in winter. Paired observations of Cff and the lower troposphere enhancements (Δgas) of 22 other anthropogenic gases (CH4, CO, halo‐ and hydrocarbons and others) measured in the same samples are used to determine apparent emission ratios for each gas. We then scale these ratios by the well known U.S. fossil fuel CO2 emissions to provide observationally based estimates of national emissions for each gas and compare these to “bottom up” estimates from inventories. Correlations of Δgas with Cff for almost all gases are statistically significant with median r2for winter, summer and the entire year of 0.59, 0.45, and 0.42, respectively. Many gases exhibit statistically significant winter:summer differences in ratios that indicate seasonality of emissions or chemical destruction. The variability of ratios in a given season is not readily attributable to meteorological or geographic variables and instead most likely reflects real, short‐term spatiotemporal variability of emissions. Key Points 14CO2 partitions PBL CO2 into fossil‐fuel and biospheric fractions Even in winter, biospheric CO2 comprises >50% of PBL CO2 enhancement Ratios of gases to 14CO2 lead to 'absolute' emissions of those gases
ISSN:0148-0227
2156-2202
DOI:10.1029/2011JD017048