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| Titel |
50 MHz continuous wave interferometer observations of the unstable mid-latitude E-region ionosphere |
| VerfasserIn |
C. Haldoupis, A. Bourdillon, A. Kamburelis, G. C. Hussey, J. A. Koehler |
| 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. 7 ; Nr. 21, no. 7, S.1589-1600 |
| Datensatznummer |
250014665
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| Publikation (Nr.) |
 copernicus.org/angeo-21-1589-2003.pdf |
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| Zusammenfassung |
In this paper we describe
the conversion of SESCAT (Sporadic-E SCATter experiment), a bistatic 50 MHz
continuous wave (CW) Doppler radar located on the island of Crete, Greece, to a
single (east-west) baseline interferometer. The first results show that SESCAT,
which provides high quality Doppler spectra and excellent temporal resolution,
has its measurement capabilities enhanced significantly when operated as an
interferometer, as it can also study short-term dynamics of localized
scattering regions within mid-latitude sporadic E-layers. The interferometric
observations reveal that the aspect sensitive area viewed by the radar often
contains a few zonally located backscatter regions, presumably blobs or patches
of unstable metallic ion plasma, which drift across the radar field-of-view
with the neutral wind. On average, these active regions of backscatter have
mean zonal scales ranging from a few kilometers to several tens of kilometers
and drift with westward speeds from ~ 20 m/s to 100 m/s, and occasionally up to
150 m/s. The cross-spectral analysis shows that mid-latitude type 1 echoes
occur much more frequently than has been previously assumed and they originate
in single and rather localized areas of elevated electric fields. On the other
hand, typical bursts of type 2 echoes are often found to result from two
adjacent regions in azimuth undergoing the same bulk motion westwards but
producing scatter of opposite Doppler polarity, a fact that contradicts the
notion of isotropic turbulence to which type 2 echoes are attributed. Finally,
quasi-periodic (QP) echoes are observed simply to be due to sequential unstable
plasma patches or blobs which traverse across the radar field-of-view,
sometimes in a wave-like fashion.
Key words. Ionosphere (ionospheric
irregularities; mid-latitude ionosphere; plasma waves and instabilities) |
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