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| Titel |
Latitudinal and seasonal variations of lower atmospheric inertial gravity wave energy revealed by US radiosonde data |
| VerfasserIn |
S. D. Zhang, F. Yi, C. M. Huang, Q. Zhou |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 28, no. 5 ; Nr. 28, no. 5 (2010-05-06), S.1065-1074 |
| Datensatznummer |
250016827
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| Publikation (Nr.) |
 copernicus.org/angeo-28-1065-2010.pdf |
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| Zusammenfassung |
| The latitudinal and seasonal variations of gravity wave
(GW) potential energy density (EP), kinetic energy density (EK), and
total energy density (ET), i.e, the sum of potential and kinetic energy
densities in the tropospheric (typically 2–10 km) and lower stratospheric
(typically 18–25 km) segments have been derived from 10 years (1998–2007) of
radiosonde observations over 92 United States stations in the Northern
Hemisphere. The latitudinal variation of EP in the lower stratosphere is
in good agreement with satellite observations. However, EK and ET in
the lower stratosphere are different from satellite observations and the
difference is believed to be linked with the latitudinal dependence of GW
sources. Our analysis reveals that GW energy properties exhibit distinctive
latitudinal and seasonal variations. The upward-propagating GW energy in the
troposphere is larger than that in the lower stratosphere at low latitudes
but the opposite holds true at high latitudes. The transition latitude,
where the upward- propagating energies in the two altitude regions are the
same, occurs at 35° N throughout the year. So striking differences
between GW activity in the troposphere and lower stratosphere are not likely
explained only by the background wind Doppler shifting due to strong
tropospheric jets. Our analysis indicates that the region around tropopause,
roughly from 10 km to 18 km, is an important source region, especially at
latitudes below 35° N. Our studies strongly suggest that in order to
fully understand the global GW activity in the lower atmosphere, the GW
kinetic energy and its geographical and seasonal variations should be
included, and more attention should be given to GWs in the troposphere and
GW sources within the intermediate region, especially the upper troposphere. |
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