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| Titel |
Short vertical-wavelength inertia-gravity waves generated by a jet–front system at Arctic latitudes – VHF radar, radiosondes and numerical modelling |
| VerfasserIn |
A. Réchou, S. Kirkwood  , J. Arnault, P. Dalin |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 13 ; Nr. 14, no. 13 (2014-07-03), S.6785-6799 |
| Datensatznummer |
250118863
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| Publikation (Nr.) |
 copernicus.org/acp-14-6785-2014.pdf |
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| Zusammenfassung |
| Inertia-gravity waves with very short vertical wavelength (λz≤1000 m)
are a very common feature of the lowermost stratosphere as
observed by the 52 MHz radar ESRAD (Esrange MST radar) in northern Scandinavia (67.88° N,
21.10° E). The waves are seen most clearly in
radar-derived profiles of buoyancy frequency (N). Here, we present a case
study of typical waves from 21 February to 22 February 2007. Good
agreement between N2 derived from radiosondes and by radar shows the
validity of the radar determination of N2. Large-amplitude wave
signatures in N2 are clearly observed by the radar and the radiosondes in
the lowermost stratosphere, from 9 km to 14–16 km height. Vertical profiles
of horizontal wind components and potential temperature from the radiosondes
show the same waves. Mesoscale simulations with the Weather Research and
Forecasting (WRF) model are carried out to complement the analysis of the
waves. Good agreement between the radar and radiosonde measurements and the
model (except for the wave amplitude) shows that the model gives realistic
results and that the waves are closely associated to the upper-level front
in an upper-troposphere jet–front system. Hodographs of the wind
fluctuations from the radiosondes and model data show that the waves
propagate upward in the lower stratosphere confirming that the origin of the
waves is in the troposphere. The observations and modelling all indicate
vertical wavelengths of 700 ± 200 m. The radiosonde hodograms indicate
horizontal wavelengths between 40 and 110 km and intrinsic periods between 6
and 9 h. The wave amplitudes indicated by the model are however an order of
magnitude less than in the observations. Finally, we show that the profiles
of N2 measured by the radar can be used to estimate wave amplitudes,
horizontal wavelengths, intrinsic periods and momentum fluxes which are
consistent with the estimates from the radiosondes. |
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