HR: 1340h
AN: SA33A-1127    [Abstracts]
TI: Collisional shear instability and equatorial spread {\em F}
AU: * Hysell, D L
EM: dlh37@cornell.edu
AF: Earth and Atmospheric Science, Cornell University, Ithaca, NY 14853 United States
AU: Kudeki, E
EM: erhan@uiuc.edu
AF: Electrical and Computer Engineering, University of Illinois, Urbana, IL 61801 United States
AB: This paper analyzes the possible role of shear flow in initiating equatorial spread {\em F} events. A new 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 waves with wavelengths close to 4$\pi$ times the shear scale length could become comparable to that of the collisional interchange instability in the equatorial {\em F} region ionosphere under ideal conditions. An initial value simulation of a nonlinear model of the instability run under realistic conditions meanwhile produces growing waves with an initial wavelength of about 30 km. The simulation results are consistent with recent Jicamarca and Altair radar observations indicating large-scale plasma waves in the bottomside equatorial ionosphere at sunset prior to the onset of spread {\em F} conditions.
DE: 2415 Equatorial ionosphere
DE: 2439 Ionospheric irregularities
DE: 2471 Plasma waves and instabilities
SC: SPA-Aeronomy [SA]
MN: 2004 AGU Fall Meeting