 |
| Titel |
The southern stratospheric gravity wave hot spot: individual waves and their momentum fluxes measured by COSMIC GPS-RO |
| VerfasserIn |
N. P. Hindley, C. J. Wright, N. D. Smith, N. J. Mitchell |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 14 ; Nr. 15, no. 14 (2015-07-16), S.7797-7818 |
| Datensatznummer |
250119902
|
| Publikation (Nr.) |
 copernicus.org/acp-15-7797-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
| Nearly all general circulation models significantly fail to reproduce the
observed behaviour of the southern wintertime polar vortex. It has been
suggested that these biases result from an underestimation of gravity wave
drag on the atmosphere at latitudes near 60° S, especially around the
"hot spot" of intense gravity wave fluxes above the mountainous Southern
Andes and Antarctic peninsula. Here, we use Global Positioning System
radio occultation (GPS-RO) data from the COSMIC satellite constellation to
determine the properties of gravity waves in the hot spot and beyond. We show
considerable southward propagation to latitudes near 60° S of waves
apparently generated over the southern Andes. We propose that this
propagation may account for much of the wave drag missing from the models.
Furthermore, there is a long leeward region of increased gravity wave energy
that sweeps eastwards from the mountains over the Southern Ocean. Despite its
striking nature, the source of this region has historically proved difficult
to determine. Our observations suggest that this region includes both waves
generated locally and orographic waves advected downwind from the hot spot.
We describe and use a new wavelet-based analysis technique for the
quantitative identification of individual waves from COSMIC temperature
profiles. This analysis reveals different geographical regimes of wave
amplitude and short-timescale variability in the wave field over the Southern
Ocean. Finally, we use the increased numbers of closely spaced pairs of
profiles from the deployment phase of the COSMIC constellation in 2006 to
make estimates of gravity wave horizontal wavelengths. We show that, given
sufficient observations, GPS-RO can produce physically reasonable estimates
of stratospheric gravity wave momentum flux in the hot spot that are
consistent with measurements made by other techniques. We discuss our results
in the context of previous satellite and modelling studies and explain how
they advance our understanding of the nature and origins of waves in the
southern stratosphere. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|