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| Titel |
Quantifying gravity waves and turbulence in the stratosphere using satellite measurements of stellar scintillation |
| VerfasserIn |
V. F. Sofieva, A. S. Gurvich, F. Dalaudier |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250029832
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| Zusammenfassung |
| Stellar scintillations observed through the Earth atmosphere are caused by air density
irregularities generated mainly by internal gravity waves (GW) and turbulence. The strength
of scintillation measurements is that they cover the transition between the saturated part of
the gravity wave spectrum and isotropic turbulence. This allows visualization of
gravity wave breaking and of resulting turbulence. We analyzed the scintillation
measurements by GOMOS fast photometers on board the Envisat satellite in order to
quantify GW and turbulence activity in the stratosphere. The analysis is based on
reconstruction of GW and turbulence spectra parameters by fitting the modeled
scintillation spectra to the measured ones. We use a two-component spectral model
of air density irregularities: the first component corresponds to the gravity wave
spectrum, while the second one describes locally isotropic turbulence resulting from
GW breaking and other instabilities. The retrieval of GW and turbulence spectra
parameters - structure characteristics, inner and outer scales of the GW component - is
based on the maximum likelihood method. In this presentation, we show global
distributions, seasonal and interannual variations of the GW and turbulence spectra
parameters retrieved from GOMOS data in 2002-2005, for altitudes 30-50 km. In
addition, we show global distributions of GW potential energy per unit mass and of
turbulent structure characteristic CT2. In our presentation, we pay special attention to
gravity wave breaking. Since other measurements at such small scales are very
scarce in this altitude range, the obtained global distributions provide unique and
complementary information about small-scale air density irregularities in the stratosphere. |
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