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Titel |
Surface pressure retrieval from SCIAMACHY measurements in the O2 A Band: validation of the measurements and sensitivity on aerosols |
VerfasserIn |
B. Diedenhoven, O. P. Hasekamp, I. Aben |
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. 8 ; Nr. 5, no. 8 (2005-08-11), S.2109-2120 |
Datensatznummer |
250003029
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Publikation (Nr.) |
copernicus.org/acp-5-2109-2005.pdf |
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Zusammenfassung |
We perform surface pressure retrievals from cloud-free Oxygen A band
measurements of SCIAMACHY. These retrievals can be well validated
because surface pressure is a quantity that is, in general, accurately
known from meteorological models. Therefore, surface pressure
retrievals and their validation provide important insight into the
quality of the instrument calibration. Furthermore, they can provide
insight into retrievals which are affected by similar radiation
transport processes, for example the retrieval of total columns of
H2O, CO, CO2 and CH4. In our retrieval aerosols are
neglected. Using synthetic measurements, it is shown that for low to
moderate surface albedos this leads to an underestimation of the
retrieved surface pressures. For high surface albedos this generally
leads to an overestimation of the retrieved surface pressures. The
surface pressures retrieved from the SCIAMACHY measurements indeed
show this dependence on surface albedo, when compared to the
corresponding pressures from a meteorological database. However, an
offset of about 20 hPa was found, which can not be caused by
neglecting aerosols in the retrieval. The same offset was found when
comparing the retrieved surface pressures to those retrieved from
co-located GOME Oxygen A band measurements. This implies a calibration
error in the SCIAMACHY measurements. By adding an offset of 0.86% of
the continuum reflectance at 756 nm to the SCIAMACHY reflectance
measurements, this systematic bias vanishes. |
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