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| Titel |
A perspective on the fundamental quality of GPS radio occultation data |
| VerfasserIn |
T.-K. Wee, Y.-H. Kuo |
| 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 ; 8, no. 10 ; Nr. 8, no. 10 (2015-10-14), S.4281-4294 |
| Datensatznummer |
250116638
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| Publikation (Nr.) |
 copernicus.org/amt-8-4281-2015.pdf |
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| Zusammenfassung |
| Radio occultation (RO) is a promising source of observation for weather and
climate applications. However, the uncertainties arising from imperfect
retrieval algorithms may weaken the overall confidence in the data and
discourage their use. As an alternative approach of assessing the quality of
RO data while avoiding the nuisance of retrieval errors, this study proposes
to use minimally processed data (measurement) instead of derived RO data.
This study compares measured phase paths with their model counterparts,
simulated with an effective ray tracer for which the refractive indices
along the complete ray path linking the transmitter and the receiver are
realistically specified. The comparison of phase measurements with the
European Centre for Medium-Range Weather Forecasts (ECMWF) data made in the
observation space shows that the RO measurements are of sufficient accuracy
to uncover regional-scale systematic errors in ECMWF's operational analysis
and the 45-year reanalysis (ERA40), and to clearly depict the error growth
of short-term ERA40 forecasts. In the southern hemispheric stratosphere, in
particular, the RO measurements served as a robust reference against which
both of the two analyses were significantly biased in opposite directions
even though they were produced by the same center using virtually the same
set of data. The measurement and ECMWF analyses showed a close agreement in
the standard deviation except for the regions and heights that the quality
of the ECMWF data is controversial. This confirms the high precision of RO
measurements and also indicates that the main problem of the ECMWF analyses
lies in their systematic error. |
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