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| Titel |
Climate intercomparison of GPS radio occultation, RS90/92 radiosondes and GRUAN from 2002 to 2013 |
| VerfasserIn |
F. Ladstädter, A. K. Steiner, M. Schwarz, 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 ; 8, no. 4 ; Nr. 8, no. 4 (2015-04-23), S.1819-1834 |
| Datensatznummer |
250116302
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| Publikation (Nr.) |
 copernicus.org/amt-8-1819-2015.pdf |
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| Zusammenfassung |
| Observations from the GPS radio occultation (GPSRO) satellite technique
and from the newly established GCOS Reference Upper Air Network (GRUAN)
are both candidates to serve as reference observations in the Global
Climate Observing System (GCOS). Such reference observations are key to
decrease existing uncertainties in upper-air climate research. There are
now more than 12 years of data available from GPSRO, with the
recognized properties high accuracy, global coverage, high vertical
resolution, and long-term stability. These properties make GPSRO
a suitable choice for comparison studies with other upper-air
observational systems. The GRUAN network consists of reference radiosonde
ground stations (16 at present), which adhere to the GCOS climate
monitoring principles. In this study, we intercompare GPSRO temperature
and humidity profiles and Vaisala RS90/92 data from the "standard"
global radiosonde network over the whole 2002 to 2013 time
frame. Additionally, we include the first years of GRUAN data (using
Vaisala RS92), available since 2009. GPSRO profiles which occur within
3 h and 300 km of radiosonde launches are used. Overall
very good agreement is found between all three data sets with temperature
differences usually less than 0.2 K. In the stratosphere above
30 hPa, temperature differences are larger but still within
0.5 K. Day/night comparisons with GRUAN data reveal small
deviations likely related to a warm bias of the radiosonde data at high
altitudes, but also residual errors from the GPSRO retrieval process
might play a role. Vaisala RS90/92 specific humidity exhibits a dry bias
of up to 40% in the upper troposphere, with a smaller bias at
lower altitudes within 15%. GRUAN shows a marked improvement in
the bias characteristics, with less than 5% difference to GPSRO,
up to 300 hPa. GPSRO dry temperature and physical temperature are
validated using radiosonde data as reference. We find that GPSRO provides
valuable long-term stable reference observations with well-defined error
characteristics for climate applications and for anchoring other
upper-air measurements. |
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