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| Titel |
Precise pointing knowledge for SCIAMACHY solar occultation measurements |
| VerfasserIn |
K. Bramstedt, S. Noël, H. Bovensmann, M. Gottwald, 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 ; 5, no. 11 ; Nr. 5, no. 11 (2012-11-27), S.2867-2880 |
| Datensatznummer |
250003180
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| Publikation (Nr.) |
 copernicus.org/amt-5-2867-2012.pdf |
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| Zusammenfassung |
| We present a method to precisely determine the viewing direction for solar
occultation instruments from scans over the solar disk. Basic idea is the fit
of the maximum intensity during the scan, which corresponds to the center of
the solar disk in the scanning direction. We apply this method to the solar
occultation measurements of the satellite instrument SCIAMACHY, which scans
the Sun in elevation direction. The achieved mean precision is 0.46 mdeg,
which corresponds to an tangent height error of about 26 m for individual
occultation sequences. The deviation of the derived elevation angle from the
geolocation information given along with the product has a seasonal cycle
with an amplitude of 2.26 mdeg, which is in tangent height an amplitude of
about 127 m. The mean elevation angle offset is −4.41 mdeg (249 m).
SCIAMACHY's sun follower device controls the azimuth viewing direction during
the occultation measurements. The derived mean azimuth direction has an
standard error of 0.65 mdeg, which is about 36 m in horizontal direction
at the tangent point. We observe also a seasonal cycle of the azimuth
mispointing with an amplitude of 2.3 mdeg, which is slightly increasing
with time. The almost constant mean offset is 88 mdeg, which is about
5.0 km horizontal offset at the tangent point. |
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