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| Titel |
Finland HF and Esrange MST radar observations of polar mesosphere summer echoes |
| VerfasserIn |
T. Ogawa, N. F. Arnold, S. Kirkwood  , N. Nishitani, Mark Lester |
| 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 ; 21, no. 4 ; Nr. 21, no. 4, S.1047-1055 |
| Datensatznummer |
250014616
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| Publikation (Nr.) |
 copernicus.org/angeo-21-1047-2003.pdf |
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| Zusammenfassung |
Peculiar near range
echoes observed in summer with the SuperDARN HF radar in Finland are presented.
The echoes were detected at four frequencies of 9, 11, 13 and 15 MHz at slant
ranges of 105–250 km for about 100 min. Interferometer measurements indicate
that the echoes are returned from 80–100 km altitudes with elevation angles
of 20°–60°. Echo power (< 16 dB), Doppler
velocity (between –30 and + 30 ms-1) and spectral width (<
60 ms-1) fluctuate with periods of several to 20 min, perhaps due to
short–period atmospheric gravity waves. When the HF radar detected the
echoes, a vertical incidence MST radar, located at Esrange in Sweden (650 km
north of the HF radar site), observed polar mesosphere summer echoes (PMSE) at
altitudes of 80–90 km. This fact suggests that the near range HF echoes are
PMSE at HF band, although both radars did not probe a common volume. With
increasing radar frequency, HF echo ranges are closer to the radar site and
echo power becomes weaker. Possible mechanisms to explain these features are
discussed.
Key words. Meteorology and
atmospheric dynamics (middle atmosphere dynamics; thermospheric dynamics; waves
and tides; instruments and techniques) |
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