Abstract
Vertical shear in th 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 tell-tale 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.
Original language | English (US) |
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Pages (from-to) | 2647-2655 |
Number of pages | 9 |
Journal | Annales Geophysicae |
Volume | 23 |
Issue number | 7 |
DOIs | |
State | Published - 2005 |
Keywords
- Ionosphere (Equatorial ionosphere; ionospheric irregularities)
- Space plasma physics (Waves and instabilities)
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Geology
- Atmospheric Science
- Earth and Planetary Sciences (miscellaneous)
- Space and Planetary Science