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| Titel |
High spatial and temporal resolution observations of an impulse-driven field line resonance in radar backscatter artificially generated with the Tromsø heater |
| VerfasserIn |
T. K. Yeoman, D. M. Wright, T. R. Robinson, J. A. Davies, M. Rietveld |
| 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 ; 15, no. 6 ; Nr. 15, no. 6, S.634-644 |
| Datensatznummer |
250012823
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| Publikation (Nr.) |
 copernicus.org/angeo-15-634-1997.pdf |
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| Zusammenfassung |
| The CUTLASS Finland HF radar has been
operated in conjunction with the EISCAT Tromsø RF ionospheric heater facility
to examine a ULF wave characteristic of the development of a field line
resonance (FLR) driven by a cavity mode caused by a magnetospheric impulse. When
the heater is on, striating the ionosphere with field-aligned ionospheric
electron density irregularities, a large enough radar target is generated to
allow post-integration over only 1 second. When combined with 15 km range gates,
this gives radar measurements of a naturally occurring ULF wave at a far better
temporal and spatial resolution than has been achieved previously. The
time-dependent signature of the ULF wave has been examined as it evolves from a
large-scale cavity resonance, through a transient where the wave period was
latitude-dependent and the oscillation had the characteristics of freely ringing
field lines, and finally to a very narrow, small-scale local field line
resonance. The resonance width of the FLR is only 60 km and this is compared
with previous observations and theory. The FLR wave signature is strongly
attenuated in the ground magnetometer data. The characterisation of the impulse
driven FLR was only achieved very crudely with the ground magnetometer data and,
in fact, an accurate determination of the properties of the cavity and field
line resonant systems challenges the currently available limitations of
ionospheric radar techniques. The combination of the latest ionospheric radars
and facilities such as the Tromsø ionospheric heater can result in a powerful
new tool for geophysical research. |
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