Service Communautaire d'Information sur la Recherche et le Développement - CORDIS

FP5

COCO Résumé de rapport

Project ID: EVG1-CT-2001-00056
Financé au titre de: FP5-EESD
Pays: France

Error analysis of the differential absorption method

A detailed error analysis of the differential absorption method has been performed (Dufour and Bréon, 2003), which forms the principle of SCIAMACHY instrument as well as the forthcoming OCO instrument (Crisp et al., 2004). This study showed that the knowledge of the spectroscopic parameters and the impact of scattering by aerosols and undetected clouds constitute the two most limiting factors affecting the accuracy of the retrievals.

Indeed, first retrievals from the SCIAMACHY instrument also show encouraging CO2 column concentration patterns, which, however, indicate that indeed aerosols may induce a serious bias of up to 3ppm. In order to be useful for inversions, the retrievals must be corrected for this bias (Houweling et al., 2005).

An application of the differential absorption method using ground based solar spectra from the Kitt Peak astronomical observatory shows the potential of the method: column retrievals using the 1.6µm wave band indicate an error on the order of 1.5 ppm (RMS) compared to a forward model simulation (Dufour et al., 2004).

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CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE
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