HR: 08:55h
AN: SM21A-04    [PDF]
TI: 3-Hz Alfv\'en Wave and Electron Bursts in the Upper Ionosphere During a Substorm Intensification
AU: Burchill, J K
EM: burchill@phys.ucalgary.ca
AF: University of Calgary, Dept of Physics and Astronomy, 2500 University Drive NW, Calgary, AB T2N 1N4 Canada
AU: * Knudsen, D J
EM: knudsen@phys.ucalgary.ca
AF: University of Calgary, Dept of Physics and Astronomy, 2500 University Drive NW, Calgary, AB T2N 1N4 Canada
AU: Clemmons, J H
EM: James.H.Clemmons@aero.org
AF: The Aerospace Corporation, MS M2/254, 270 Coral Circle, El Segundo, CA 90245 United States
AU: Pfaff, R F
EM: rob.pfaff@gsfc.nasa.gov
AF: NASA GSFC, Code 696, Bldg. 2, Room 213, Greenbelt, MD 20771 United States
AU: Wallis, D D
EM: dwallis@eisa.com
AF: Magnemetrics, 2340 Briar Hill Drive, Ottawa, ON K1H 7A9 Canada
AU: Rankin, R
EM: rankin@space.ualberta.ca
AF: University of Alberta, Department of Physics,, Edmonton, AB T6G 2J1 Canada
AU: Watt, C E
EM: cwatt@space.ualberta.ca
AF: University of Alberta, Department of Physics,, Edmonton, AB T6G 2J1 Canada
AB: The GEODESIC auroral sounding rocket encountered two short-lived (several second) bursts of intense Alfv\'en waves between 800-900 km during a substorm intensification on February 26, 2000. The waves were detected with both vector electric field double probes and a vector flux gate magnetometer and carry a peak Poynting flux of ~1 mW/m$^2$, and are downward-propagating. They have a frequency near 3 Hz and appear to be very coherent, existing within a very narrow bandwidth. They show no sign of reflection from the ionosphere below, and also no sign of direct coupling (density perturbations or particle heating) with the local plasma. The observations are consistent with a horizontal wavelength of order 1 km. The waves were associated with electron acceleration several thousand km above the ionosphere, resulting in velocity-dispersed bursts with energies exceeding 1 keV at times. The higher energies and the detailed shape of the dispersion curves challenge simple, two-fluid models of wave propagation and electron acceleration, and indicate the need for additional physical mechanisms to explain their characteristics. We discuss possible improvements to the models.
DE: 2407 Auroral ionosphere (2704)
DE: 2736 Magnetosphere/ionosphere interactions
DE: 2772 Plasma waves and instabilities
DE: 2788 Storms and substorms
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting