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| Titel |
Auroral ion acoustic wave enhancement observed with a radar interferometer system |
| VerfasserIn |
N. M. Schlatter, V. Belyey, B. Gustavsson, N. Ivchenko, D. Whiter, H. Dahlgren, S. Tuttle, T. Grydeland |
| 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 ; 33, no. 7 ; Nr. 33, no. 7 (2015-07-20), S.837-844 |
| Datensatznummer |
250121219
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| Publikation (Nr.) |
 copernicus.org/angeo-33-837-2015.pdf |
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| Zusammenfassung |
| Measurements of naturally enhanced ion acoustic line (NEIAL) echoes obtained
with a five-antenna interferometric imaging radar system are presented. The
observations were conducted with the European Incoherent SCATter (EISCAT)
radar on Svalbard and the EISCAT Aperture Synthesis Imaging receivers (EASI)
installed at the radar site. Four baselines of the interferometer are used in
the analysis. Based on the coherence estimates derived from the measurements,
we show that the enhanced backscattering region is of limited extent in the
plane perpendicular to the geomagnetic field. Previously it has been argued
that the enhanced backscatter region is limited in size; however, here the
first unambiguous observations are presented. The size of the enhanced
backscatter region is determined to be less than 900 × 500 m,
and at times less than 160 m in the direction of the longest antenna
separation, assuming the scattering region to have a Gaussian scattering
cross section in the plane perpendicular to the geomagnetic field. Using
aperture synthesis imaging methods volumetric images of the NEIAL echo are
obtained showing the enhanced backscattering region to be aligned with the
geomagnetic field. Although optical auroral emissions are observed outside
the radar look direction, our observations are consistent with the NEIAL echo
occurring on field lines with particle precipitation. |
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