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| Titel |
Evidence of systematic errors in SCIAMACHY-observed CO2 due to aerosols |
| VerfasserIn |
S. Houweling, W. Hartmann, I. Aben, H. Schrijver, J. Skidmore, G.-J. Roelofs, F.-M. Bréon |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 5, no. 11 ; Nr. 5, no. 11 (2005-11-08), S.3003-3013 |
| Datensatznummer |
250003145
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| Publikation (Nr.) |
 copernicus.org/acp-5-3003-2005.pdf |
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| Zusammenfassung |
| SCIAMACHY CO2 measurements show a large variability in total column CO2
over the Sahara desert of up to 10%, which is not anticipated from in situ
measurements and cannot be explained by results of atmospheric models.
Comparisons with colocated aerosol measurements by TOMS and MISR over the
Sahara indicate that the seasonal variation of SCIAMACHY-observed CO2
strongly resembles seasonal variations of windblown dust. Correlation
coefficients of monthly datasets of colocated MISR aerosol optical depth and
SCIAMACHY CO2 vary between 0.6 and 0.8, indicating that about half of the
CO2 variance is explained by aerosol optical depth. Radiative transfer
model calculations confirm the role of dust and can explain the size of the
errors. Sensitivity tests suggest that the remaining variance may largely be
explained by variations in the vertical distribution of dust. Further
calculations for a few typical aerosol classes and a broad range of
atmospheric conditions show that the impact of aerosols on SCIAMACHY
retrieved CO2 is by far the largest over the Sahara, but may also reach
significant levels elsewhere. Over the continents, aerosols lead mostly to
overestimated CO2 columns with the exception of biomass burning plumes and
dark coniferous forests. Inverse modelling calculations confirm that aerosol
correction of SCIAMACHY CO2 measurements is needed to derive meaningful
source and sink estimates. Methods for correcting aerosol-induced errors
exist, but so far mainly on the basis of theoretical considerations. As
demonstrated by this study, SCIAMACHY may contribute to a verification of
such methods using real data. |
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