 |
| Titel |
The wintertime two-day wave in the polar stratosphere, mesosphere and lower thermosphere |
| VerfasserIn |
D. J. Sandford, M. J. Schwartz, N. J. Mitchell |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 8, no. 3 ; Nr. 8, no. 3 (2008-02-13), S.749-755 |
| Datensatznummer |
250005558
|
| Publikation (Nr.) |
 copernicus.org/acp-8-749-2008.pdf |
|
|
|
|
|
| Zusammenfassung |
| Recent observations of the polar mesosphere have revealed that waves with
periods near two days reach significant amplitudes in both summer and
winter. This is in striking contrast to mid-latitude observations where
two-day waves maximise in summer only. Here, we use data from a meteor radar
at Esrange (68° N, 21° E) in the Arctic and data from the MLS
instrument aboard the EOS Aura satellite to investigate the wintertime polar
two-day wave in the stratosphere, mesosphere and lower thermosphere. The
radar data reveal that mesospheric two-day wave activity measured by
horizontal-wind variance has a semi-annual cycle with maxima in winter and
summer and equinoctial minima. The MLS data reveal that the summertime wave
in the mesosphere is dominated by a westward-travelling zonal wavenumber
three wave with significant westward wavenumber four present. It reaches
largest amplitudes at mid-latitudes in the southern hemisphere. In the
winter polar mesosphere, however, the wave appears to be an
eastward-travelling zonal wavenumber two, which is not seen during the
summer. At the latitude of Esrange, the eastward-two wave reaches maximum
amplitudes near the stratopause and appears related to similar waves
previously observed in the polar stratosphere. We conclude that the
wintertime polar two-day wave is the mesospheric manifestation of an
eastward-propagating, zonal-wavenumber-two wave originating in the
stratosphere, maximising at the stratopause and likely to be generated by
instabilities in the polar night jet. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|