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| Titel |
An assessment of differences in lower stratospheric temperature records from (A)MSU, radiosondes, and GPS radio occultation |
| VerfasserIn |
F. Ladstädter, A. K. Steiner, U. Foelsche, L. Haimberger, C. Tavolato, G. Kirchengast |
| 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 ; 4, no. 9 ; Nr. 4, no. 9 (2011-09-21), S.1965-1977 |
| Datensatznummer |
250002101
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| Publikation (Nr.) |
 copernicus.org/amt-4-1965-2011.pdf |
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| Zusammenfassung |
| Uncertainties for upper-air trend patterns are still substantial.
Observations from the radio occultation (RO) technique offer new
opportunities to assess the existing observational records
there. Long-term time series are available from radiosondes and from the
(Advanced) Microwave Sounding Unit (A)MSU. None of them were originally
intended to deliver data for climate applications. Demanding
intercalibration and homogenization procedures are required to account
for changes in instrumentation and observation techniques. In this
comparative study three (A)MSU anomaly time series and two homogenized
radiosonde records are compared to RO data from the CHAMP, SAC-C, GRACE-A
and F3C missions for September 2001 to December 2010. Differences of
monthly anomalies are examined to assess the differences in the datasets
due to structural uncertainties. The difference of anomalies of the
(A)MSU datasets relative to RO shows a statistically significant trend
within about (−0.2±0.1) K/10 yr (95% confidence
interval) at all latitudes. This signals a systematic deviation of the
two datasets over time. The radiosonde network has known deficiencies in
its global coverage, with sparse representation of most of the southern
hemisphere, the tropics and the oceans. In this study the error that
results from sparse sampling is estimated and accounted for by
subtracting it from radiosonde and RO datasets. Surprisingly the sampling
error correction is also important in the Northern Hemisphere (NH), where
the radiosonde network is dense over the continents but does not capture
large atmospheric variations in NH winter. Considering the sampling
error, the consistency of radiosonde and RO anomalies is improving
substantially; the trend in the anomaly differences is generally very
small. Regarding (A)MSU, its poor vertical resolution poses another
problem by missing important features of the vertical atmospheric
structure. This points to the advantage of homogeneously distributed
measurements with high vertical resolution. |
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