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| Titel |
The decay of radar echoes from meteors with particular reference to their use in the determination of temperature fluctuations near the mesopause |
| VerfasserIn |
W. Jones |
| 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 ; 13, no. 10 ; Nr. 13, no. 10, S.1104-1106 |
| Datensatznummer |
250012012
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| Publikation (Nr.) |
 copernicus.org/angeo-13-1104-1995.pdf |
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| Zusammenfassung |
| The rate of decay of a radar echo from an
ionised meteor train will be governed by the diffusion coefficient of the plasma
and this in turn will depend on the temperature. Very recently the temperature
fluctuations near the mesopause have been monitored by this means, by the
recording of the decay times of underdense trains. The usual derivation of the
precise expression relating the underdense echo decay time to the temperature
contains two important assumptions, (i) that the train is created with a
Gaussian ionisation profile, and (ii) that kinetic theory may be applied to
calculate the diffusion coefficient. We investigate the effect of these
assumptions, showing that the first assumption is unnecessary, an underdense
backscatter echo decaying exponentially with a decay time equal to
λ2/(32π2D), where
λ is the wavelength and D the diffusion coefficient, independently
of the initial distribution. However, the second assumption is shown to be
incorrect, and whereas according to kinetic theory D∝T1/2/ρ,
where T and ρ are the atmospheric temperature and density, the
correct result is D∝Tρ. This leads to an
appreciable correction to the results for the temperature fluctuations. |
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