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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 109, A11301, doi:10.1029/2004JA010636, 2004

Collisional shear instability in the equatorial F region ionosphere

D. L. Hysell

Department of Earth and Atmospheric Science, Cornell University, Ithaca, New York, USA


E. Kudeki

Department of Electrical and Computer Engineering, University of Illinois, Urbana, Illinois, USA


Abstract

A collisional shear instability in a magnetized plasma is described and evaluated. The instability is related to electrostatic Kelvin Helmholtz but operates in inhomogeneous plasmas in the collisional regime. Boundary value analysis predicts that the linear growth rate for the instability could be comparable to that of the collisional interchange instability in the equatorial F region ionosphere under ideal conditions. An initial value simulation of a nonlinear model of the instability run under realistic conditions produces growing waves with a relatively long growth time (50 min) and with an initial wavelength of about 30 km. The simulation results are consistent with recent radar observations showing large-scale plasma waves in the bottomside equatorial ionosphere at sunset prior to the onset of spread F conditions. The role of shear instability in preconditioning the F region for interchange instabilities to occur after sunset is discussed.

Received 17 June 2004; accepted 27 August 2004; published 3 November 2004.

Keywords: coherent scatter radar; ionospheric irregularities; shear; equatorial spread F; plasma instability; equatorial ionosphere.

Index Terms: 2471 Ionosphere: Plasma waves and instabilities; 2415 Ionosphere: Equatorial ionosphere; 2439 Ionosphere: Ionospheric irregularities; 6929 Radio Science: Ionospheric physics (2409).

Subscriber Access to Full Article (Nonsubscribers may purchase for $9.00, Includes print PDF, file size: 3647457 bytes)

Citation: Hysell, D. L., and E. Kudeki (2004), Collisional shear instability in the equatorial F region ionosphere, J. Geophys. Res., 109, A11301, doi:10.1029/2004JA010636.