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| Titel |
The dynamical background of polar mesosphere winter echoes from simultaneous EISCAT and ESRAD observations |
| VerfasserIn |
E. Belova, S. Kirkwood  , J. Ekeberg, A. Osepian, I. Häggström, H. Nilsson, M. Rietveld |
| 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. 4 ; Nr. 23, no. 4 (2005-06-03), S.1239-1247 |
| Datensatznummer |
250015219
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| Publikation (Nr.) |
 copernicus.org/angeo-23-1239-2005.pdf |
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| Zusammenfassung |
| On 30 October 2004 during a strong solar proton event, layers of enhanced
backscatter from altitudes between 55 and 75km have been observed by both
ESRAD (52MHz) and the EISCAT VHF (224MHz) radars. These echoes have
earlier been termed Polar Mesosphere Winter Echoes, PMWE. After considering
the morphology of the layers and their relation to observed atmospheric
waves, we conclude that the radars have likely seen the same phenomenon even
though the radars' scattering volumes are located about 220km apart and
that the most long-lasting layer is likely associated with wind-shear in an
inertio-gravity wave. An ion-chemistry model is used to determine parameters
necessary to relate wind-shear induced turbulent energy dissipation rates to
radar backscatter. The model is verified by comparison with electron density
profiles measured by the EISCAT VHF radar. Observed radar signal strengths
are found to be 2-3 orders of magnitude stronger than the maximum which can
be expected from neutral turbulence alone, assuming that previously
published results relating radar signal scatter to turbulence parameters,
and turbulence parameters to wind shear, are correct. The possibility
remains that some additional or alternative mechanism may be involved in
producing PMWE, such as layers of charged dust/smoke particles or large
cluster ions. |
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