Possible ionospheric preconditioning by shear flow leading to equatorial spread F

• Autores: Hysell, D. L., Kudeki, E., Chau Chong Shing, Jorge Luis
• Formato: artículo
• Fecha de Publicación: 2005
• Institución: Instituto Geofísico del Perú
• Repositorio: IGP-Institucional
• Lenguaje: inglés
• OAI Identifier: oai:repositorio.igp.gob.pe:20.500.12816/1876
• Enlace del recurso: http://hdl.handle.net/20.500.12816/1876; https://doi.org/10.5194/angeo-23-2647-2005
• Nivel de acceso: acceso abierto
• Materia: Ionosphere; Equatorial ionosphere; Ionospheric irregularities; Plasma waves; http://purl.org/pe-repo/ocde/ford#1.05.01

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.