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| Titel |
Observation and simulation of wave breaking in the southern hemispheric stratosphere during VORCORE |
| VerfasserIn |
M. Moustaoui, H. Teitelbaum, A. Mahalov |
| 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 ; 31, no. 4 ; Nr. 31, no. 4 (2013-04-16), S.675-687 |
| Datensatznummer |
250019024
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| Publikation (Nr.) |
 copernicus.org/angeo-31-675-2013.pdf |
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| Zusammenfassung |
| An interesting occurrence of a Rossby wave breaking event observed during the
VORCORE experiment is presented and explained. Twenty-seven balloons were
launched inside the Antarctic polar vortex. Almost all of these balloons
evolved in the stratosphere around 500K within the vortex, except the one
launched on 28 October 2005. In this case, the balloon was caught within a
tongue of high potential vorticity (PV), and was ejected from the polar
vortex. The evolution of this event is studied for the period between 19 and
25 November 2005. It is found that at the beginning of this period, the polar
vortex experienced distortions due to the presence of Rossby waves. Then,
these waves break and a tongue of high PV develops. On 25 November, the
tongue became separated from the vortex and the balloon was ejected into the
surf zone. Lagrangian simulations demonstrate that the air masses surrounding
the balloon after its ejection were originating from the vortex edge. The
wave breaking and the development of the tongue are confined within a region
where a planetary Quasi-Stationary Wave 1 (QSW1) induces wind speeds with
weaker values. The QSW1 causes asymmetry in the wind speed and the horizontal
PV gradient along the edge of the polar vortex, resulting in a localized jet.
Rossby waves with smaller scales propagating on top of this jet amplify as
they enter the jet exit region and then break. The role of the QSW1 on the
formation of the weak flow conditions that caused the non-linear wave
breaking observed near the vortex edge is confirmed by three-dimensional
numerical simulations using forcing with and without the contribution of the
QSW1. |
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