Fig. 4

Evaluation of XCO₂, XCH₄ and XCO from the CHE nature run (NR). The nature run is compared to total column FTIR observation^35,60 at the TCCON stations^{67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90} (OBS). The crosses indicate that the bias is statistically significant (p-value < 0.01).