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| Titel |
A method for improved SCIAMACHY CO2 retrieval in the presence of optically thin clouds |
| VerfasserIn |
M. Reuter, M. Buchwitz, O. Schneising, J. Heymann, H. Bovensmann, J. P. Burrows |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 3, no. 1 ; Nr. 3, no. 1 (2010-02-12), S.209-232 |
| Datensatznummer |
250000824
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| Publikation (Nr.) |
 copernicus.org/amt-3-209-2010.pdf |
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| Zusammenfassung |
| 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. |
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