HR: 0800h
AN: SM51A-0338    [Abstracts]
TI: Plasma instabilities in auroral ionospheric density gradients from 120-200 km altitude
AU: * Dyrud, L P
EM: ldyrud@bu.edu
AF: Center for Space Physics Boston University, 725 Commonwealth Ave., Boston, MA 02215 United States
AU: Semeter, J
EM: jls@bu.edu
AF: Center for Space Physics Boston University, 725 Commonwealth Ave., Boston, MA 02215 United States
AU: Oppenheim, M
EM: meerso@bu.edu
AF: Center for Space Physics Boston University, 725 Commonwealth Ave., Boston, MA 02215 United States
AB: Recent observations by the Sonderstrom incoherent scatter radar show narrow field aligned filaments of enhanced plasma density extending from ~100 to 400 km in altitude, with widths of order 1 km transverse to B, and with peak density of ~5e11/m3. These features typically appear at the footprint of nightside reconnection where strong, sheared, ionospheric flows exist. We examine the stability of such structures when immersed within plasma convection using a 2-D (plane perpendicular to the magnetic field) hybrid plasma simulation. Initial results indicated the relatively rapid development (order seconds) of gradient drift type instability waves; for parameters near 200 km altitude, and convection velocity of 600 m/s, such plasma columns are found to be unstable to waves with a wavelength of ~10 to 20 m. These results have implications for the interpretation of HF backscatter measurements in such ionospheric regions.
DE: 6929 Ionospheric physics (2409)
DE: 2159 Plasma waves and turbulence
DE: 2407 Auroral ionosphere (2704)
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting