A method for improved SCIAMACHY CO 2 retrieval in the presence of optically thin clouds

By M. Reuter, Michael Buchwitz, Oliver Schneising, J. Heymann, Heinrich Bovensmann, John P. Burrows. 2009

158 citations recorded by the source corpus.

Abstract. An optimal estimation based retrieval scheme for satellite based retrievals of XCO2 (the dry air column averaged mixing ratio of atmospheric CO2) is presented enabling accurate retrievals also in the presence of thin clouds. The proposed method is designed to analyze near-infrared nadir measurements of the SCIAMACHY instrument in the CO2 absorption band at 1580 nm and in the O2-A absorption band at around 760 nm. The algorithm accounts for scattering in an optically thin cirrus cloud layer and at aerosols of a default profile. The scattering information is mainly obtained from the O2-A band and a merged fit windows approach enables the transfer of information between the O2-A and the CO2 band. Via the optimal estimation technique, the algorithm is able to account for a priori information to further constrain the inversion. Test scenarios of simulated SCIAMACHY sun-normalized radiance measurements are analyzed in order to specify the quality of the proposed method. In contrast to existing algorithms for SCIAMACHY retrievals, the systematic errors due to cirrus clouds with optical thicknesses up to 1.0 are reduced to values below 4 ppm for most of the analyzed scenarios. This shows that the proposed method has the potential to reduce uncertainties of SCIAMACHY retrieved XCO2 making this data product potentially useful for surface flux inverse modeling.

Subfields: Atmospheric Science, Global and Planetary Change

View Paper: https://www.semanticscholar.org/paper/43ff60db1be76be59439a1e8e8012ff57eb6cb42

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Citations in the corpus

Retrieval of atmospheric CO2 with enhanced accuracy and precision from SCIAMACHY: validation with FTS measurements and comparison with model results (2011, methodology): “[50] 1. CWP, CTH and APS are “effective” values and a quantitative one‐to‐one agreement with corresponding GEMS or CALIPSO values cannot be expected [ Reuter et al., 2010 ].”
The ACOS CO 2 retrieval algorithm – Part 1: Description and validation against synthetic observations (2011, methodology): “Many approaches have been devised to account for scattering affects in the retrieval of carbon dioxide (e.g., Kuang et al., 2002; Bösch et al., 2006; Connor et al., 2008; Oshchepkov et al., 2008, 2009; Yoshida et al., 2011; Reuter et al., 2010).”
Disentangling chlorophyll fluorescence from atmospheric scattering effects in O2 A‐band spectra of reflected sun‐light (2011, background): “…the atmosphere and thereby minimize the impact of aerosols and thin clouds on the retrieval of CO2, which is performed in additional channels covering CO2 absorption bands at 1.61 and 2.06 mm [Bösch et al., 2006; Connor et al., 2008; Oshchepkov et al., 2008; Butz et al., 2009; Reuter et al., 2010].”