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| Titel |
Operational profiling of temperature using ground-based microwave radiometry at Payerne: prospects and challenges |
| VerfasserIn |
U. Löhnert, O. Maier |
| 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 ; 5, no. 5 ; Nr. 5, no. 5 (2012-05-21), S.1121-1134 |
| Datensatznummer |
250002868
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| Publikation (Nr.) |
 copernicus.org/amt-5-1121-2012.pdf |
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| Zusammenfassung |
The motivation of this study is to verify theoretical expectations placed on
ground-based microwave radiometer (MWR) techniques and to confirm whether
they are suitable for supporting key missions of national weather services,
such as timely and accurate weather advisories and warnings. We evaluate
reliability and accuracy of atmospheric temperature profiles retrieved
continuously by the microwave profiler system HATPRO (Humidity And
Temperature PROfiler) operated at the aerological station of Payerne
(MeteoSwiss) in the time period August 2006–December 2009. Assessment is
performed by comparing temperatures from the radiometer against temperature
measurements from a radiosonde accounting for a total of 2107
quality-controlled all-season cases.
In the evaluated time period, the MWR delivered reliable temperature
profiles in 86% of all-weather conditions on a temporal resolution of
12–13 min. Random differences between MWR and radiosonde are down to 0.5 K
in the lower boundary layer and increase to 1.7 K at 4 km height. The
differences observed between MWR and radiosonde in the lower boundary layer
are similar to the differences observed between the radiosonde and another
in-situ sensor located on a close-by 30 m tower. Temperature retrievals from
above 4 km contain less than 5% of the total information content of the
measurements, which makes clear that this technique is mainly suited for
continuous observations in the boundary layer. Systematic temperature
differences are also observed throughout the retrieved profile and can
account for up to ±0.5 K. These errors are due to offsets in the
measurements of the microwave radiances that have been corrected for in data
post-processing and lead to nearly bias-free overall temperature retrievals.
Different reasons for the radiance offsets are discussed, but cannot be
unambiguously determined retrospectively. Monitoring and, if necessary,
corrections for radiance offsets as well as a real-time rigorous automated
data quality control are mandatory for microwave profiler systems that are
designated for operational temperature profiling. In the analysis of a
subset of different atmospheric situations, it is shown that lifted
inversions and data quality during precipitation present the largest
challenges for operational MWR temperature profiling. |
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