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| Titel |
Rocket and radar investigation of background electrodynamics and bottom-type scattering layers at the onset of equatorial spread F |
| VerfasserIn |
D. L. Hysell, M. F. Larsen, C. M. Swenson, A. Barjatya, T. F. Wheeler, T. W. Bullett, M. F. Sarango, R. F. Woodman, J. L. Chau, D. Sponseller |
| 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 ; 24, no. 5 ; Nr. 24, no. 5 (2006-07-03), S.1387-1400 |
| Datensatznummer |
250015555
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| Publikation (Nr.) |
 copernicus.org/angeo-24-1387-2006.pdf |
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| Zusammenfassung |
| Sounding rocket experiments were conducted during the NASA EQUIS II
campaign on Kwajalein Atoll designed to elucidate the electrodynamics
and layer structure of the postsunset equatorial F region
ionosphere prior to the onset of equatorial spread F
(ESF). Experiments took place on 7 and 15 August 2004, each comprised
of the launch of an instrumented and two chemical release sounding
rockets. The instrumented rockets measured plasma number density,
vector electric fields, and other parameters to an apogee of about
450 km. The chemical release rockets deployed trails of trimethyl aluminum
(TMA) which yielded wind profile measurements. The Altair radar was
used to monitor coherent and incoherent scatter in UHF and VHF bands.
Electron density profiles were also measured with rocket beacons and
an ionosonde. Strong plasma shear flow was evident in both
experiments. Bottom-type scattering layers were observed mainly in the
valley region, below the shear nodes, in westward-drifting plasma
strata. The layers were likely produced by wind-driven interchange
instabilities as proposed by
Kudeki and Bhattacharyya (1999). In both experiments, the layers were patchy and
distributed periodically in space. Their horizontal structure was
similar to that of the large-scale plasma depletions that formed later
at higher altitude during ESF conditions. We argue that the
bottom-type layers were modulated by the same large-scale waves that
seeded the ESF. A scenario where the large-scale waves were themselves
produced by collisional shear instabilities is described. |
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