Open AccessContribution of the Orbiting Carbon Observatory to the estimation of CO 2 sources and sinks: Theoretical study in a variational data assimilation framework
Author(s) -
Chevallier Frédéric,
Bréon FrançoisMarie,
Rayner Peter J.
Publication year - 2007
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2006jd007375
Subject(s) - observatory , satellite , environmental science , standard deviation , data assimilation , northern hemisphere , meteorology , atmospheric sciences , carbon cycle , remote sensing , physics , statistics , mathematics , geology , astrophysics , ecology , astronomy , ecosystem , biology
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 column‐averaged 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.