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CarbonTracker
 
Statistical Comparison with Independent Vertical Profiles (CT2007B)
Here were present a statistical summary of comparisons of the optimized CO2 mole fraction distribution produced by CarbonTracker and a set of ~19,000 independent (not used in CarbonTracker) CO2 observations from air samples collected in the free troposphere as part of the NOAA ESRL Aircraft Program between 2001 and 2006. Figure 1 below shows the distribution of the residuals (model minus observations) for all aircraft samples by month. The mean and standard deviation of the distribution is 0.20 ± 2.15 ppm.


Figure 1
For comparison, figure 2 shows a similar bias when comparing optimized CO2 mole fractions and the observed surface observations that were used in the assimilation (-0.01 ± 2.33 ppm). This suggests that part to of the difference is in the phase and amplitude of the seasonally varying fluxes and not in the vertical transport.


Figure 2