1Department of Physics, University of Toronto, 60 St. George Street, Toronto, Ontario, M5S 1A7, Canada
2Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena CA, 91109, USA
3Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6290, USA
4Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, UK
5Department of Geography, University of Toronto, 45 St. George Street, Toronto, Ontario, M5S 2E5, Canada
6Max-Planck-Institut für Chemie, Air Chemistry Division, Mainz, Germany
7Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO, 80305-3337, USA
8Climate Research Division, Environment Canada, 4905 Dufferin St., Toronto, Ontario, M3H 5T4, Canada
*now at: Climate Research Division, Environment Canada, 4905 Dufferin St., Toronto, Ontario, M3H 5T4, Canada
Received: 19 Dec 2010 – Discussion started: 07 Feb 2011
Abstract. We infer CO2 surface fluxes using satellite observations of mid-tropospheric CO2 from the Tropospheric Emission Spectrometer (TES) and measurements of CO2 from surface flasks in a time-independent inversion analysis based on the GEOS-Chem model. Using TES CO2 observations over oceans, spanning 40° S–40° N, we find that the horizontal and vertical coverage of the TES and flask data are complementary. This complementarity is demonstrated by combining the datasets in a joint inversion, which provides better constraints than from either dataset alone, when a posteriori CO2 distributions are evaluated against independent ship and aircraft CO2 data. In particular, the joint inversion offers improved constraints in the tropics where surface measurements are sparse, such as the tropical forests of South America. Aggregating the annual surface-to-atmosphere fluxes from the joint inversion for the year 2006 yields −1.13±0.21 Pg C for the global ocean, −2.77±0.20 Pg C for the global land biosphere and −3.90±0.29 Pg C for the total global natural flux (defined as the sum of all biospheric, oceanic, and biomass burning contributions but excluding CO2 emissions from fossil fuel combustion). These global ocean and global land fluxes are shown to be near the median of the broad range of values from other inversion results for 2006. To achieve these results, a bias in TES CO2 in the Southern Hemisphere was assessed and corrected using aircraft flask data, and we demonstrate that our results have low sensitivity to variations in the bias correction approach. Overall, this analysis suggests that future carbon data assimilation systems can benefit by integrating in situ and satellite observations of CO2 and that the vertical information provided by satellite observations of mid-tropospheric CO2 combined with measurements of surface CO2, provides an important additional constraint for flux inversions.
Revised: 15 Jun 2011 – Accepted: 15 Jun 2011 – Published: 24 Jun 2011
Nassar, R., Jones, D. B. A., Kulawik, S. S., Worden, J. R., Bowman, K. W., Andres, R. J., Suntharalingam, P., Chen, J. M., Brenninkmeijer, C. A. M., Schuck, T. J., Conway, T. J., and Worthy, D. E.: Inverse modeling of CO2 sources and sinks using satellite observations of CO2 from TES and surface flask measurements, Atmos. Chem. Phys., 11, 6029-6047, doi:10.5194/acp-11-6029-2011, 2011.