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| Titel |
Possible ionospheric preconditioning by shear flow leading to equatorial spread F |
| VerfasserIn |
D. L. Hysell, E. Kudeki, J. L. Chau |
| 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 ; 23, no. 7 ; Nr. 23, no. 7 (2005-10-14), S.2647-2655 |
| Datensatznummer |
250015337
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| Publikation (Nr.) |
 copernicus.org/angeo-23-2647-2005.pdf |
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| Zusammenfassung |
Vertical shear in the zonal plasma drift speed is apparent in
incoherent and coherent scatter radar observations of the bottomside
F region ionosphere made at Jicamarca from about 1600–2200
LT. The relative importance of the factors controlling the shear,
which include competition between the E and F region
dynamos as well as vertical currents driven in the E and F
regions at the dip equator, is presently unknown. Bottom-type
scattering layers arise in strata where the neutral and plasma drifts
differ widely, and periodic structuring of irregularities within the
layers is telltale of intermediate-scale waves in the
bottomside. These precursor waves appear to be able to seed
ionospheric interchange instabilities and initiate full-blown
equatorial spread F. The seed or precursor waves may be
generated by a collisional shear instability. However, assessing the
viability of shear instability requires measurements of the same
parameters needed to understand shear flow quantitatively -
thermospheric neutral wind and off-equatorial conductivity
profiles.
Keywords. Ionosphere (Equatorial ionosphere; ionospheric
irregularities) – Space plasma physics (Waves and instabilities) |
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