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| Titel |
Simultaneous observations of equatorial F-region plasma depletions over Brazil during the Spread-F Experiment (SpreadFEx) |
| VerfasserIn |
P.-D. Pautet, M. J. Taylor, N. P. Chapagain, H. Takahashi, A. F. Medeiros, F. T. São Sabbas, D. C. Fritts |
| 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. 6 ; Nr. 27, no. 6 (2009-06-08), S.2371-2381 |
| Datensatznummer |
250016551
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| Publikation (Nr.) |
 copernicus.org/angeo-27-2371-2009.pdf |
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| Zusammenfassung |
From September to November 2005, the NASA Living with a Star program
supported the Spread-F Experiment campaign (SpreadFEx) in Brazil to study
the effects of convectively generated gravity waves on the ionosphere and
their role in seeding Rayleigh-Taylor instabilities, and associated
equatorial plasma bubbles. Several US and Brazilian institutes deployed a
broad range of instruments (all-sky imagers, digisondes, photometers,
meteor/VHF radars, GPS receivers) covering a large area of Brazil. The
campaign was divided in two observational phases centered on the September
and October new moon periods. During these periods, an Utah State University
(USU) all-sky CCD imager operated at São João d'Aliança (14.8° S,
47.6° W), near Brasilia, and a Brazilian all-sky CCD imager located
at Cariri (7.4° S, 36° W), observed simultaneously the evolution of
the ionospheric bubbles in the OI (630 nm) emission and the mesospheric
gravity wave field. The two sites had approximately the same magnetic
latitude (9–10° S) but were separated in longitude by ~1500 km.
Plasma bubbles were observed on every clear night (17 from Brasilia and 19
from Cariri, with 8 coincident nights). These joint datasets provided
important information for characterizing the ionospheric depletions during
the campaign and to perform a novel longitudinal investigation of their
variability. Measurements of the drift velocities at both sites are in good
agreement with previous studies, however, the overlapping fields of view
revealed significant differences in the occurrence and structure of the
plasma bubbles, providing new evidence for localized generation. This paper
summarizes the observed bubble characteristics important for related
investigations of their seeding mechanisms associated with gravity wave
activity. |
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