Carbon Dioxide Columns from SCIAMACHY (FSI-WFM-DOAS)

Retrieval of Carbon Dioxide columns from SCIAMACHY using FSI WFM-DOAS (U Leicester)

Total columns of atmospheric CO₂ are derived from SCIAMACHY NIR spectral measurements, using the Full Spectral Initiation (FSI) WFM-DOAS algorithm (Barkley et al., ACP, 2006a). The FSI algorithm is a development of the WFM-DOAS retrieval technique (Buchwitz et al., JGR, 2000), whereby the trace gas total column can be derived through a linear least squares fit of a model reference spectrum and its derivatives, or 'weighting functions', to the observe sun-normalised radiance. The low natural variability of atmospheric CO₂ requires satellite measurements to be made accurately and at high precision. The FSI algorithm keeps potential error sources to a minimum through the inclusion of a-priori data into the retrieval.

Validation against ground-based FTIR observations and model data (Barkley et al., ACP, 2006b), indicate that the precision of monthly gridded SCIAMACHY/FSI CO₂ is approaching the 1% with a negative bias of about 4%. Furthermore, comparisons of SCIAMACHY/FSI CO₂ to CO₂ distributions derived from the AIRS instrument over North America during 2003 show good qualitative agreement (Barkley et al, GRL, 2006).

Sample results

SCIAMACHY/FSI CO2 - Jun 2003	SCIAMACHY/FSI CO2 - Oct 2003

Archives

Documentation

Background information

• Barkley, M., Paul S. Monks, and Richard J. Engelen, Comparison of SCIAMACHY and AIRS CO₂ measurements over North America during the summer and autumn of 2003, Geophys. Res. Lett., 33, L20805, doi:10.1029/2006GL026807, 2006.
• Barkley, M. P., U. Frieß, and P. S. Monks, Measuring atmospheric CO₂ from space using Full Spectral Initialisation (FSI) WFM-DOAS, Atmos. Chem. Phys., 6, 3517, 2006.
• Barkley, M. P., P. S. Monks, U. Frieß, R. L. Mittermeier, H. Fast, S. Körner, and M. Heimann, Comparisions between SCIAMACHY atmospheric CO2 retrieved using (FSI) WFM-DOAS to ground based FTIR data and the TM3 chemistry transport model, Atmos. Chem. Phys., 6, 4483-4498, 2006.

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Last modified: July 2009