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| Titel |
Seasonal and local time variability of ripples from airglow imager observations in US and Japan |
| VerfasserIn |
J. Yue, T. Nakamura, C.-Y. She, M. Weber, W. Lyons, T. Li |
| 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 ; 28, no. 7 ; Nr. 28, no. 7 (2010-07-02), S.1401-1408 |
| Datensatznummer |
250016855
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| Publikation (Nr.) |
 copernicus.org/angeo-28-1401-2010.pdf |
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| Zusammenfassung |
| Ripples as seen in airglow imagers are small wavy structures with short
horizontal wavelengths (<15 km). Ripples are thought to form as the result
of local instabilities, which are believed to occur when the amplitude of
gravity waves becomes large enough. We have investigated ripple formation
based on years of airglow imager observations located at Fort Collins,
Colorado (41° N, 105° W) and Misato Observatory, Japan (34° N,
135° E)/Shigaraki MU Observatory (35° N, 136° E). Na
temperature-wind lidar observations are employed to detect convective and
dynamic instabilities in the mesosphere and lower thermosphere (MLT) region
over Fort Collins, Colorado. Seasonal variation of the ripple occurrence in
Colorado is compared to that of the lidar-measured instability. The
occurrence frequency of ripples varies semiannually, with maxima occurring
during solstices and minima during equinoxes in both Colorado and Japan.
However, the probability of convective and dynamic instabilities varies
annually with a peak in Colorado winter. The seasonal variation of the
occurrence frequency of ripples correlates with that of the gravity wave
variances in the MLT. Ripple occurrence over Colorado also shows strong local
time dependence, but it bears little resemblance to the local time dependence
of instability probability. |
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