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| Titel |
GPS radio occultation with CHAMP and SAC-C: global monitoring of thermal tropopause parameters |
| VerfasserIn |
T. Schmidt, S. Heise, J. Wickert, G. Beyerle, C. Reigber |
| 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. 6 ; Nr. 5, no. 6 (2005-06-15), S.1473-1488 |
| Datensatznummer |
250002899
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| Publikation (Nr.) |
 copernicus.org/acp-5-1473-2005.pdf |
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| Zusammenfassung |
| In this study the global lapse-rate tropopause (LRT) pressure,
temperature, potential temperature, and sharpness are discussed
based on Global Positioning System (GPS) radio occultations (RO)
from the German CHAMP (CHAllenging Minisatellite Payload) and the
U.S.-Argentinian SAC-C (Satelite de Aplicaciones Cientificas-C)
satellite missions. Results with respect to seasonal variations
are compared with operational radiosonde data and ECMWF (European
Centre for Medium-Range Weather Forecast) operational analyses.
Results on the tropical quasi-biennial oscillation (QBO) are
updated from an earlier study. CHAMP RO data are available
continuously since May 2001 with on average 150 high resolution
temperature profiles per day. SAC-C data are available for several
periods in 2001 and 2002. In this study temperature data from
CHAMP for the period May 2001-December 2004 and SAC-C data from
August 2001-October 2001 and March 2002-November 2002 were used,
respectively. The bias between GPS RO temperature profiles and
radiosonde data was found to be less than 1.5K between 300 and
10hPa with a standard deviation of 2-3K. Between 200-20hPa the
bias is even less than 0.5K (2K standard deviation). The mean
deviations based on 167699 comparisons between CHAMP/SAC-C and
ECMWF LRT parameters are (-2.1±37.1)hPa for pressure and
(0.1±4.2)K for temperature. Comparisons of LRT pressure and
temperature between CHAMP and nearby radiosondes (13230) resulted
in (5.8±19.8)hPa and (-0.1±3.3)K, respectively. The
comparisons between CHAMP/SAC-C and ECMWF show on average the
largest differences in the vicinity of the jet streams with up to
700m in LRT altitude and 3K in LRT temperature, respectively.
The CHAMP mission generates the first long-term RO data set. Other
satellite missions will follow (GRACE, COSMIC, MetOp, TerraSAR-X,
EQUARS) generating together some thousand temperature profiles
daily. |
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