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| Titel |
On the spectrum of vertically propagating gravity waves generated by a transient heat source |
| VerfasserIn |
M. J. Alexander, J. R. Holton |
| 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 ; 4, no. 4 ; Nr. 4, no. 4 (2004-06-23), S.923-932 |
| Datensatznummer |
250001829
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| Publikation (Nr.) |
 copernicus.org/acp-4-923-2004.pdf |
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| Zusammenfassung |
| It is commonly believed that cumulus convection preferentially
generates gravity waves with tropospheric vertical wavelengths
approximately twice the depth of the convective heating. Individual
cumulonimbus, however, act as short term transient heat sources
(duration 10 to 30min). Gravity waves generated by such sources
have broad frequency spectra and a wide range of vertical scales. The
high-frequency components tend to have vertical wavelengths much
greater than twice the depth of the heating. Such waves have large
vertical group velocities, and are only observed for a short duration
and at short horizontal distances from the convective source. At
longer times and longer distances from the source the dominant wave
components have short vertical wavelengths and much slower group
velocities, and thus are more likely to be observed even though their
contribution to the momentum flux in the upper stratosphere and
mesosphere may be less than that of the high frequency waves. These
properties of convectively generated waves are illustrated by a linear
numerical model for the wave response to a specified transient heat
source. The wave characteristics are documented through Fourier and
Wavelet analysis, and implications for observing systems are
discussed. |
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