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| Titel |
Simulations of the gravity wave field in the lower stratosphere during VORCORE |
| VerfasserIn |
Riwal Plougonven, Antonin Arsac, Albert Hertzog, Lionel Guez, François Vial |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250041137
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| Zusammenfassung |
| The Vorcore experiment (Sept. 2005-Feb. 2006, Hertzog et al, J. Atmos. Ocean. Techno.,
2007) consisted of 27 flights of superpressure balloons in the lower stratosphere, in
the Southern Polar vortex. The quasi-Lagrangian measurements have provided a
unique database for the study of the gravity wave field due to the wide domain
covered, the duration of the experiment and the quasi-Lagrangian nature of the
measurements (giving direct accesss to intrinsic frequencies). In complement to this
observational campaign, high-resolution (dx = 20Â km) simulations using the Weather
Research and Forecast model have been carried out which describe the flow in
a wide domain (10,000 km à 10,000 km) above Antarctica and the Southern
Ocean.
At the altitudes of the balloon flights (around 16 and 19 km), the simulations are
compared to the observations in two ways: comparison of the averaged characteristics of the
gravity wave field (momentum fluxes, intermittency) on one hand, and case studies of
particularly intense wave packets on the other. This comparison shows that the simulations
reproduce a fair portion of the gravity wave motions, though generally underestimating the
amplitudes of the waves. The simulations are then used to explore further and at
different heights the characteristics of the gravity wave field (spatial distribution,
large scale wakes of topographies, intensities and associated fluxes, intermittency).
Particular attention is paid to the differing characteristics of the gravity wave field above
topographies (more intense but more intermittent) and above the oceans or flat
terrain. |
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