Towards constraints on fossil fuel emissions from total column carbon dioxide 1California Institute of Technology, Pasadena, CA, USA
26 Apr 2013
2University of California, Irvine, CA, USA
3Colorado State University, Fort Collins, CO, USA
Received: 01 Nov 2012 – Published in Atmos. Chem. Phys. Discuss.: 21 Nov 2012Abstract. We assess the large-scale, top-down constraints on regional fossil fuel
emissions provided by observations of atmospheric total column CO2,
XCO2. Using an atmospheric general
circulation model (GCM) with underlying fossil
emissions, we determine the influence of regional fossil fuel emissions on
global XCO2 fields. We quantify the regional contrasts between
source and upwind regions and probe the sensitivity of atmospheric
XCO2 to changes in fossil fuel emissions. Regional fossil fuel
XCO2 contrasts can exceed 0.7 ppm based on 2007 emission
estimates, but have large seasonal variations due to biospheric fluxes.
Contamination by clouds reduces the discernible fossil signatures.
Nevertheless, our simulations show that atmospheric fossil
XCO2 can be tied to its source region and that changes in the
regional XCO2 contrasts scale linearly with emissions. We test
the GCM results against XCO2 data from the GOSAT satellite.
Regional XCO2 contrasts in GOSAT data generally scale with the
predictions from the GCM, but the comparison is limited by the moderate
precision of and relatively few observations from the satellite. We discuss
how this approach may be useful as a policy tool to verify national fossil
emissions, as it provides an independent, observational constraint.
Revised: 26 Feb 2013 – Accepted: 22 Mar 2013 – Published: 26 Apr 2013
Citation: Keppel-Aleks, G., Wennberg, P. O., O'Dell, C. W., and Wunch, D.: Towards constraints on fossil fuel emissions from total column carbon dioxide, Atmos. Chem. Phys., 13, 4349-4357, doi:10.5194/acp-13-4349-2013, 2013.