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D. L. Hysell; E. Kudeki; J. L. Chau (2005)
Publisher: Copernicus Publications
Journal: Annales Geophysicae
Languages: English
Types: Article
Subjects: Geophysics. Cosmic physics, Q, [ SDU.STU ] Sciences of the Universe [physics]/Earth Sciences, [ SDU.OCEAN ] Sciences of the Universe [physics]/Ocean, Atmosphere, Science, Physics, QC1-999, QC801-809

Classified by OpenAIRE into

arxiv: Physics::Space Physics, Physics::Geophysics
International audience; 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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