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| Titel |
Excitation thresholds of field-aligned irregularities and associated ionospheric hysteresis at very high latitudes observed using SPEAR-induced HF radar backscatter |
| VerfasserIn |
D. M. Wright, R. S. Dhillon, T. K. Yeoman, T. R. Robinson, E. C. Thomas, L. J. Baddeley, S. Imber |
| 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 ; 27, no. 7 ; Nr. 27, no. 7 (2009-07-01), S.2623-2631 |
| Datensatznummer |
250016575
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| Publikation (Nr.) |
 copernicus.org/angeo-27-2623-2009.pdf |
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| Zusammenfassung |
| On 10 October 2006 the SPEAR high power radar facility was operated in a
power-stepping mode where both CUTLASS radars were detecting backscatter
from the SPEAR-induced field-aligned irregularities (FAIs). The effective
radiated power of SPEAR was varied from 1–10 MW. The aim of the experiment
was to investigate the power thresholds for excitation (Pt) and
collapse (Pc) of artificially-induced FAIs in the ionosphere over
Svalbard. It was demonstrated that FAI could be excited by a SPEAR ERP of
only 1 MW, representing only 1/30th of SPEAR's total capability, and that
once created the irregularities could be maintained for even lower powers.
The experiment also demonstrated that the very high latitude ionosphere
exhibits hysteresis, where the down-going part of the power cycle provided a
higher density of irregularities than for the equivalent part of the
up-going cycle. Although this second result is similar to that observed
previously by CUTLASS in conjunction with the Tromsø heater, the same is
not true for the equivalent incoherent scatter measurements. The EISCAT
Svalbard Radar (ESR) failed to detect any hysteresis in the plasma
parameters over Svalbard in stark contract with the measurements made using
the Tromsø UHF. |
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