%0 Journal Article
%A Heather Graven
%A Marc L Fischer
%A T Lueker
%A Seongeun Jeong
%A Tom Guilderson
%A Ralph Keeling
%A Ray P Bambha
%A Kieran Brophy
%A W Callahan
%A Xinguang Cui
%A C Frankenberg
%A Kevin R Gurney
%A Brian W LaFranchi
%A Scott J Lehman
%A Hope A Michelsen
%A John B Miller
%A Sally Newman
%A W Paplawsky
%A Nicholas Parazoo
%A Christopher D Sloop
%A S.J Walker
%B Environmental Research Letters
%D 2018
%G eng
%N 6
%P 065007
%R 10.1088/1748-9326/aabd43
%T Assessing fossil fuel CO <sub>2</sub> emissions in California using atmospheric observations and models
%V 13
%8 01/2018
%! Environ. Res. Lett.
%X <p>Analysis systems incorporating atmospheric observations could provide a powerful tool for validating fossil fuel CO<sub>2</sub> (ffCO<sub>2</sub>) emissions reported for individual regions, provided that fossil fuel sources can be separated from other CO<sub>2</sub> sources or sinks and atmospheric transport can be accurately accounted for. We quantified ffCO<sub>2</sub> by measuring radiocarbon (<sup>14</sup>C) in CO<sub>2</sub>, an accurate fossil-carbon tracer, at nine observation sites in California for three months in 2014–15. There is strong agreement between the measurements and ffCO<sub>2</sub> simulated using a high-resolution atmospheric model and a spatiotemporally-resolved fossil fuel flux estimate. Inverse estimates of total in-state ffCO<sub>2</sub> emissions are consistent with the California Air Resources Board's reported ffCO<sub>2</sub> emissions, providing tentative validation of California's reported ffCO<sub>2</sub> emissions in 2014–15. Continuing this prototype analysis system could provide critical independent evaluation of reported ffCO<sub>2</sub> emissions and emissions reductions in California, and the system could be expanded to other, more data-poor regions.</p>