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| Titel |
Coordinated radar observations of plasma wave characteristics in the auroral F region |
| VerfasserIn |
R. A. Makarevich, W. A. Bristow |
| 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 ; 32, no. 7 ; Nr. 32, no. 7 (2014-07-29), S.875-888 |
| Datensatznummer |
250121087
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| Publikation (Nr.) |
 copernicus.org/angeo-32-875-2014.pdf |
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| Zusammenfassung |
| Properties of decameter-scale plasma waves in the auroral F region are
investigated using coordinated observations of plasma wave characteristics
with the Kodiak HF coherent radar (KOD) and Poker Flat Incoherent Scatter
Radar (PFISR) systems in the Alaskan sector. We analyze one event on
14 November 2012 that occurred during the first PFISR Ion-Neutral
Observations in the Thermosphere (PINOT) campaign when exceptionally good
F region backscatter data at 1 s resolution were collected by KOD over the
wide range of locations also monitored by PFISR. In particular, both radar
systems were observing continuously along the same magnetic meridian, which
allowed for a detailed comparison between the line-of-sight (l-o-s) velocity
data sets. It is shown that l-o-s velocity correlation for data points
strictly matched in time (within 1 s) depends strongly on the number of
ionospheric echoes detected by KOD in a given post-integration interval or,
equivalently, on the KOD echo occurrence in that interval. The l-o-s velocity
correlations reach 0.7–0.9 for echo occurrences exceeding 70%, while also
showing considerable correlations of 0.5–0.6 for occurrences as low as
10%. Using the same approach of strictly matching the KOD and PFISR data
points, factors controlling coherent echo power are investigated, focusing on
the electric field and electron density dependencies. It is demonstrated that
the signal-to-noise ratio (SNR) of F region echoes increases nearly monotonically
with an increasing electric field strength as well as with an increasing
electron density, except at large density values, where SNR drops
significantly. The electric field control can be understood in terms of the
growth rate of the gradient-drift waves being proportional to the convection
drift speed under conditions of fast-changing convection flows, while the
density effect may involve over-refraction at large density values and radar
backscatter power proportionality to the perturbation density. |
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