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| Titel |
Analysis of gravity waves in the tropical middle atmosphere over La Reunion Island (21°S, 55°E) with lidar using wavelet techniques |
| VerfasserIn |
F. Chane-Ming, F. Molinaro, J. Leveau, P. Keckhut, A. Hauchecorne |
| 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 ; 18, no. 4 ; Nr. 18, no. 4, S.485-498 |
| Datensatznummer |
250013959
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| Publikation (Nr.) |
 copernicus.org/angeo-18-485-2000.pdf |
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| Zusammenfassung |
The capabilities of the continuous wavelet
transform (CWT) and the multiresolution analysis (MRA) are presented in this
work to measure vertical gravity wave characteristics. Wave properties are
extracted from the first data set of Rayleigh lidar obtained between heights of
30 km and 60 km over La Reunion Island (21°S, 55°E) during the Austral winter
in 1994 under subtropical conditions. The altitude-wavelength representations
deduced from these methods provide information on the time and spatial evolution
of the wave parameters of the observed dominant modes in vertical profiles such
as the vertical wavelengths, the vertical phase speeds, the amplitudes of
temperature perturbations and the distribution of wave energy. The spectra
derived from measurements show the presence of localized quasi-monochromatic
structures with vertical wavelengths <10 km. Three methods based on the
wavelet techniques show evidence of a downward phase progression. A first
climatology of the dominant modes observed during the Austral winter period
reveals a dominant night activity of 2 or 3 quasi-monochromatic structures with
vertical wavelengths between 1-2 km from the stratopause, 3-4 km and 6-10 km
observed between heights of 30 km and 60 km. In addition, it reveals a dominant
activity of modes with a vertical phase speed of -0.3 m/s and observed periods
peaking at 3-4 h and 9 h. The characteristics of averaged vertical wavelengths
appear to be similar to those observed during winter in the southern equatorial
region and in the Northern Hemisphere at mid-latitudes.
Key words: Meteorology and atmospheric dynamics (climatology;
middle atmosphere dynamics; waves and tides) |
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