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| Titel |
Simultaneous observations at different altitudes of ionospheric backscatter in the eastward electrojet |
| VerfasserIn |
S. E. Milan, 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 ; 16, no. 1 ; Nr. 16, no. 1, S.55-68 |
| Datensatznummer |
250013102
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| Publikation (Nr.) |
 copernicus.org/angeo-16-55-1998.pdf |
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| Zusammenfassung |
A common feature of evening near-range
ionospheric backscatter in the CUTLASS Iceland radar field of view is two
parallel, approximately L-shell-aligned regions of westward flow which
are attributed to irregularities in the auroral eastward electrojet region of
the ionosphere. These backscatter channels are separated by approximately
100–200 km in range. The orientation of the CUTLASS Iceland radar beams and the
zonally aligned nature of the flow allows an approximate determination of flow
angle to be made without the necessity of bistatic measurements. The two flow
channels have different azimuthal variations in flow velocity and spectral
width. The nearer of the two regions has two distinct spectral signatures. The
eastern beams detect spectra with velocities which saturate at or near the
ion-acoustic speed, and have low spectral widths (less than 100 m s–1),
while the western beams detect lower velocities and higher spectral widths
(above 200 m s–1). The more distant of the two channels has only one
spectral signature with velocities above the ion-acoustic speed and high
spectral widths. The spectral characteristics of the backscatter are consistent
with E-region scatter in the nearer channel and upper-E-region or F-region
scatter in the further channel. Temporal variations in the characteristics of
both channels support current theories of E-region turbulent heating and
previous observations of velocity-dependent backscatter cross-section. In
future, observations of this nature will provide a powerful tool for the
investigation of simultaneous E- and F-region irregularity generation under
similar (nearly co-located or magnetically conjugate) electric field conditions.
Key words. Auroral ionosphere · Ionospheric
irregularities · Plasma convection |
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