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| Titel |
Coherent gravity wave occurrence rates in paired satellite observations |
| VerfasserIn |
A. J. McDonald |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250064735
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| Zusammenfassung |
| Previous studies have deduced the horizontal wavelength and absolute momentum flux of
gravity waves from two or more adjacent satellite profiles by assuming that these profiles
belong to the same sinusoidal wave. However, the assumption that both profiles relate to the
same sinusoidal wave is obviously sometimes violated in regions where multiple waves exist
or where no waves exist. This presentation describes a statistical methodology to identify
pairs of profiles from satellite observations which contain the same gravity wave. This
methodology relies on comparing the magnitude of the cross S-transform derived from
normalized profile pairs with Monte Carlo simulations to identify coherent wave structures in
both profiles.
This technique also allows the percentage of paired observations which contain the
same wave packet to be derived at a given significance level. Application of this
technique to COSMIC/FORMOSAT3 data shows that the occurrence of coherent
waves varies strongly as a function of latitude and season. The latitudinal pattern is
shown to potentially be linked to the larger horizontal wavelengths of gravity waves
observed at the equator and the likely corresponding change in the size of wave
packets which increases the likelihood of two equally-spaced profiles observing the
same wave. Other possibilities include greater intermittency in the gravity wave
sources at mid-latitudes and differences in the observed wave field due to critical
level filtering beneath the observation range. Using the dense sampling geometry
provided by the COSMIC/FORMOSAT3 constellation we also examine how horizontal
separations between profiles impacts the occurrence of coherent waves in profile pairs. |
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