Contribution of the Orbiting Carbon Observatory to the estimation of CO_{2} sources and sinks: Theoretical study in a variational data assimilation framework
Abstract
NASA's Orbiting Carbon Observatory will monitor the atmospheric concentrations of carbon dioxide (CO_{2}) along the satellite subtrack over the sunlit hemisphere of the Earth for more than 2 years, starting in late 2008. This paper demonstrates the application of a variational Bayesian formalism to retrieve fluxes at high spatial and temporal resolution from the satellite retrievals. We use a randomization approach to estimate the posterior error statistics of the calculated fluxes. Given our prior information about the fluxes (with error standard deviations about 0.4 g C m^{2} d^{1} over ocean and 4 g C m^{2} d^{1} over vegetated areas) and our observation characteristics (with error standard deviations about 2 ppm), we show error reductions of up to about 40% at weekly scale for a grid point of the transport model. We simulate the impact of undetected biases by perturbing the observations and show that regional biases of a few tenths of a part per million in columnaveraged CO_{2} can bias the inverted yearly subcontinental fluxes by a few tenths of a gigaton of carbon, which is larger than the uncertainty on the anthropogenic carbon fluxes but smaller than that of natural fluxes over most vegetated areas.
 Publication:

Journal of Geophysical Research (Atmospheres)
 Pub Date:
 May 2007
 DOI:
 10.1029/2006JD007375
 Bibcode:
 2007JGRD..112.9307C
 Keywords:

 Biogeosciences: Biogeochemical cycles;
 processes;
 and modeling (0412;
 0793;
 1615;
 4805;
 4912);
 Biogeosciences: Biosphere/atmosphere interactions (0315);
 Mathematical Geophysics: Inverse theory;
 Biogeosciences: Computational methods and data processing;
 Biogeosciences: Carbon cycling (4806);
 CO<SUB>2</SUB> fluxes;
 inversion;
 satellite