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| Titel |
Gravity wave reflection and its influence on the consistency of temperature- and wind-based momentum fluxes simulated above Typhoon Ewiniar |
| VerfasserIn |
Y.-H. Kim, H.-Y. Chun, P. Preusse, M. Ern, S.-Y. Kim |
| 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 ; 12, no. 22 ; Nr. 12, no. 22 (2012-11-16), S.10787-10795 |
| Datensatznummer |
250011598
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| Publikation (Nr.) |
 copernicus.org/acp-12-10787-2012.pdf |
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| Zusammenfassung |
| For a case study of Typhoon Ewiniar performed with a mesoscale model, we
compare stratospheric gravity wave (GW) momentum flux determined from
temperature variances by applying GW polarization relations and by assuming
upward propagating waves, with GW momentum flux calculated from model winds
which is considered as a reference. The temperature-based momentum-flux
profile exhibits positive biases relative to the reference, which fluctuate
significantly with altitude. The vertically-averaged magnitude of the
positive biases is about 14% of the reference momentum flux. We found
that this deviation from the reference stems from the interference between
upward and downward propagating waves. The downward propagating GWs are due
mainly to partial reflections of upward propagating waves at altitudes where
the background wind and stability change with height. When the upward and
downward propagating waves are decomposed and their momentum fluxes are
calculated separately from temperature perturbations, the fraction of the
momentum flux arising from the downward propagating waves is about
4.5–8.2% of that from the upward propagating waves. The net momentum
flux of upward and downward propagating GWs agrees well with the reference
from the model wind perturbations. The implications of this study for the GW
momentum-flux observations from satellites are discussed. |
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