Hysell, D. L.Kudeki, E.Chau Chong Shing, Jorge Luis2018-07-162018-07-162005-10-14Hysell, D. L., Kudeki, E., & Chau, J. L. (2005). Possible ionospheric preconditioning by shear flow leading to equatorial spread F.==$Annales Geophysicae, 23$==(7), 2647-2655. https://doi.org/10.5194/angeo-23-2647-2005index-oti2018http://hdl.handle.net/20.500.12816/1876Vertical 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.application/pdfenginfo:eu-repo/semantics/openAccessIonosphereEquatorial ionosphereIonospheric irregularitiesPlasma wavesinfo:eu-repo/semantics/articlehttp://purl.org/pe-repo/ocde/ford#1.05.01Annales Geophysicaehttps://doi.org/10.5194/angeo-23-2647-2005