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| Titel |
Letter to the EditiorTesting the hypothesis of the influence of neutral turbulence on the deduction of ambipolar diffusivities from meteor trail expansion |
| VerfasserIn |
C. M. Hall, T. Aso, M. Tsutsumi, S. Nozawa, A. H. Manson, C. E. Meek |
| 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 ; 23, no. 3 ; Nr. 23, no. 3 (2005-03-30), S.1071-1073 |
| Datensatznummer |
250015202
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| Publikation (Nr.) |
 copernicus.org/angeo-23-1071-2005.pdf |
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| Zusammenfassung |
| Fading times of radar echoes from underdense meteor trails
in the upper mesosphere/lower thermosphere are commonly used to determine
ambipolar diffusivities and hence ambient temperature. Diffusivities are
generally expected to increase exponentially with height through the region
from which the meteor trail echoes are obtained, viz., typically 70-110km
altitude for a ~30-MHz radar. In practice, however, this is more the
exception: unexpectedly large diffusivities are obtained in the lower part
of the regime, and unexpectedly low values are obtained in the upper part; only
in the few kilometres on either side of the maximum in echo occurrence (viz.,
90km for a 30-MHz radar) does the diffusivity profile behave as expected.
Hall (2002) hypothesised that neutral turbulence might be enhancing expansion of
the meteor trail in the lower part of the regime. In this communication, due
to results only available since the publication of Hall's suggestion, we are
able to refute the hypothesis. |
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