Effectiveness analysis of ACOS-Xco2 bias correction method with GEOS-Chem model results

Satellite observations and model simulations are of two important data sources to study atmospheric carbon dioxide concentration. For analyzing and evaluating the bias correction method of ACOS dry-air column averaged CO 2 (Xco 2 ) product, the GEOS-Chem Xco 2 simulations are selected according to observing time and locations of the ACOS product. The GEOS-Chem simulations of CO 2 profiles are transformed to Xco 2 data by convolving with satellite averaging kernels and pressure weighting functions. The GEOS-Chem Xco 2 data are then compared with both bias uncorrected and bias corrected satellite retrievals of ACOS. The comparisons show that the bias uncorrected ACOS retrievals are on average 1.12ppm higher than the model Xco 2 data, while the corrected ACOS retrievals are only on average 0.06ppm lower than the model Xco 2 data. By assuming consistency between model Xco 2 simulations and true atmospheric Xco 2 , this study indicates that the bias can be obvious decreased through the bias correction method, and the correction is effective and necessary for satellite Xco 2 retrievals.