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| Titel |
Reference quality upper-air measurements: GRUAN data processing for the Vaisala RS92 radiosonde |
| VerfasserIn |
R. J. Dirksen, M. Sommer, F. J. Immler, D. F. Hurst, R. Kivi, H. Vömel |
| 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 ; 7, no. 12 ; Nr. 7, no. 12 (2014-12-18), S.4463-4490 |
| Datensatznummer |
250115997
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| Publikation (Nr.) |
 copernicus.org/amt-7-4463-2014.pdf |
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| Zusammenfassung |
| The GCOS (Global Climate Observing System) Reference Upper-Air Network (GRUAN) data processing for the
Vaisala RS92 radiosonde was developed to meet the criteria for
reference measurements. These criteria stipulate the collection of
metadata, the use of well-documented correction algorithms, and
estimates of the measurement uncertainty. An important and novel
aspect of the GRUAN processing is that the uncertainty estimates are
vertically resolved. This paper describes the algorithms that are
applied in version 2 of the GRUAN processing to correct for
systematic errors in radiosonde measurements of pressure,
temperature, humidity, and wind, as well as how the uncertainties
related to these error sources are derived.
Currently, the RS92 is launched on a regular basis at 13 out of 15 GRUAN sites.
An additional GRUAN
requirement for performing reference measurements with the RS92 is
that the manufacturer-prescribed procedure for the radiosonde's
preparation, i.e. heated reconditioning of the sensors and
recalibration during ground check, is followed. In the GRUAN
processing however, the recalibration of the humidity sensors that
is applied during ground check is removed. For the dominant error
source, solar radiation, laboratory experiments were performed to
investigate and model its effect on the RS92's temperature and
humidity measurements.
GRUAN uncertainty estimates are 0.15 K for night-time temperature measurements
and approximately 0.6 K at 25 km during daytime.
The other uncertainty estimates are up to 6% relative humidity for humidity, 10–50 m
for geopotential height, 0.6 hPa for pressure, 0.4–1 m s−1
for wind speed, and 1° for wind direction.
Daytime temperature profiles for GRUAN and
Vaisala processing are comparable and consistent within the
estimated uncertainty. GRUAN daytime humidity profiles are up to
15% moister than Vaisala processed profiles, of which
two-thirds is due to the radiation dry bias correction and
one-third is due to an additional calibration correction.
Redundant measurements with frost point hygrometers (CFH
and NOAA FPH) show that GRUAN-processed RS92 humidity profiles
and frost point data agree within 15% in the troposphere.
No systematic biases occur, apart from a 5% dry bias for GRUAN data
around −40 °C at night. |
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