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| Titel |
EISCAT and ESRAD radars observations of polar mesosphere winter echoes during solar proton events on 11-12 November 2004 |
| VerfasserIn |
E. Belova, S. Kirkwood  , T. Sergienko |
| 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 ; 31, no. 7 ; Nr. 31, no. 7 (2013-07-03), S.1177-1190 |
| Datensatznummer |
250019061
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| Publikation (Nr.) |
 copernicus.org/angeo-31-1177-2013.pdf |
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| Zusammenfassung |
| Polar mesosphere winter echoes (PMWE) were detected by two radars, ESRAD at
52 MHz located near Kiruna, Sweden, and EISCAT at 224 MHz located near
Tromsø, Norway, during the strong solar proton event on 11–12 November
2004. PMWE maximum volume reflectivity was estimated to be 3 ×
10−15 m−1 for ESRAD and 2 × 10−18 m−1 for
EISCAT. It was found that the shape of the echo power spectrum is close to
Gaussian inside the PMWE layers, and outside of them it is close to
Lorentzian, as for the standard ion line of incoherent scatter (IS). The EISCAT
PMWE spectral width is about 5–7 m s−1 at 64–67 km and 7–10 m s−1 at 68–70 km.
At the lower altitudes the PMWE spectral widths are close to those for the
IS ion line derived from the EISCAT data outside the layers. At the higher
altitudes the PMWE spectra are broader by 2–4 m s−1 than those for the ion
line. The ESRAD PMWE spectral widths at 67–72 km altitude are 3–5 m s−1, that
is, 2–4 m s−1 larger than ion line spectral widths modelled for the ESRAD
radar. The PMWE spectral widths for both EISCAT and ESRAD showed no
dependence on the echo strength. It was found that all these facts cannot be
explained by turbulent origin of the echoes. We suggested that evanescent
perturbations in the electron gas generated by the incident infrasound waves
may explain the observed PMWE spectral widths. However, a complete theory of
radar scatter from this kind of disturbance needs to be developed before a
full conclusion can be made. |
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