HR: 17:15h
AN: SA22C-06    [PDF]
TI: Instability of the {\sl E-F} Coupled Nighttime Midlatitude Ionosphere
AU: * Cosgrove, R B
EM: russell.cosgrove@sri.com
AF: SRI International, 333 Ravenswood Ave (G276), Menlo Park, CA 94025 United States
AU: Tsunoda, R T
EM: roland.tsunoda@sri.com
AF: SRI International, 333 Ravenswood Ave (G276), Menlo Park, CA 94025 United States
AB: The {\sl F} layer is unstable at night as described by {\sl Perkins} [1973]. Sporadic {\sl E} ($E_{s}$) layers are unstable at night as described by {\sl Cosgrove and Tsunoda} [2002a, 2003]. Both instabilities involve the growth of plane-wave altitude modulations of their respective layers, and have growth rates that maximize for a tilted orientation of the plane wave phase fronts. Using the assumption that electric fields map between the {\sl E} and {\sl F} regions along magnetic field lines, we find that under certain conditions the two instabilities reinforce one another, thus giving rise to a coupled instability of the nighttime midlatitude ionosphere. The result is a verification of the coupled process postulated in {\sl Tsunoda and Cosgrove} [2001]. The involvement of the wind-shear-driven $E_{s}$ layer polarization mechanism [{\sl Cosgrove and Tsunoda,} 2002a] significantly enhances the growth rate for {\sl F} region structure, as compared with the Perkins instability.
DE: 2437 Ionospheric dynamics
DE: 2439 Ionospheric irregularities
DE: 2443 Midlatitude ionosphere
DE: 2471 Plasma waves and instabilities
SC: SPA - Aeronomy [SA]
MN: 2003 Fall Meeting