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| Titel |
First middle-atmospheric zonal wind profile measurements with a new ground-based microwave Doppler-spectro-radiometer |
| VerfasserIn |
R. Rüfenacht, N. Kämpfer, A. Murk |
| 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. 11 ; Nr. 5, no. 11 (2012-11-07), S.2647-2659 |
| Datensatznummer |
250003165
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| Publikation (Nr.) |
 copernicus.org/amt-5-2647-2012.pdf |
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| Zusammenfassung |
We report on the wind radiometer WIRA, a new ground-based microwave Doppler-spectro-radiometer
specifically designed for the measurement of middle-atmospheric horizontal wind by observing ozone
emission spectra at 142.17504 GHz. Currently, wind speeds in five levels between 30 and
79 km can be retrieved which makes WIRA the first instrument able to continuously measure
horizontal wind in this altitude range. For an integration time of one day the measurement error
on each level lies at around 25 m s−1. With a planned upgrade this value is expected
to be reduced by a factor of 2 in the near future. On the altitude levels where our measurement
can be compared to wind data from the European Centre for Medium-Range Weather Forecasts (ECMWF)
very good agreement in the long-term statistics as well as in short time structures with
a duration of a few days has been found.
WIRA uses a passive double sideband heterodyne receiver together with a digital Fourier transform
spectrometer for the data acquisition. A big advantage of the radiometric approach is that such
instruments can also operate under adverse weather conditions and thus provide a continuous time
series for the given location. The optics enables the instrument to scan a wide range of azimuth
angles including the directions east, west, north, and south for zonal and meridional wind
measurements. The design of the radiometer is fairly compact and its calibration does not rely on
liquid nitrogen which makes it transportable and suitable for campaign use. WIRA is conceived in
a way that it can be operated remotely and does hardly require any maintenance.
In the present paper, a description of the instrument is given, and the techniques used for the
wind retrieval based on the determination of the Doppler shift of the measured atmospheric ozone
emission spectra are outlined. Their reliability was tested using Monte Carlo
simulations. Finally, a time series of 11 months of zonal wind measurements over Bern
(46°57′ N, 7°26′ E) is presented and compared to ECMWF wind data. |
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