HR: 0800h
AN: SM41B-1189    [Abstracts]
TI: Striated AKR: A Remote Tracer of Solitary Ion Structures in the Magnetosphere
AU: * Mutel, R
EM: robert-mutel@uiowa.edu
AF: University of Iowa, Dept. Physics and Astronomy Van Allen Hall, Iowa City, IA 52242 United States
AU: Menietti, D
EM: douglas-menietti@uiowa.edu
AF: University of Iowa, Dept. Physics and Astronomy Van Allen Hall, Iowa City, IA 52242 United States
AU: Christopher, I
EM: ivar-christopher@uiowa.edu
AF: University of Iowa, Dept. Physics and Astronomy Van Allen Hall, Iowa City, IA 52242 United States
AB: The Cluster Wideband Data (WBD) instrument has been used to study the characteristics of a very narrowband, striated AKR burst emission with negative drifting structure on frequency-time plots. SAKR bursts, previosuly repoted by Menietti et al (2000), are a relatively rare form of AKR (<1% duty cycle at 125 kHz). We find that drift rates are almost always negatively sloped between 3 - 12 KHz, and that the instantaneous bandwidth is much narrower than commonly observed AKR, typically 25 - 40 Hz. By comparing burst intensities received simultaneously from widely separated spacecraft, we determine the characteristic angular size of the individual bursts: The mean angular size is statistically well determined, with a Gaussian equivalent width of 4.2° ± 0.5°. Combining this result with the measured flux density of the bursts, the mean power in `elementary radiation events' is 10 -100 W, much lower than predicted in current models of AKR emission. We suggest that SAKR emission is triggered by solitary ion structures which a moving upward at speeds 50 - 250 km/s. Both the derived speeds, directions, and implied small scales sizes are consistent with the observed properties of ion solitary structures.
DE: 2704 Auroral phenomena (2407)
DE: 2730 Magnetosphere: inner
DE: 2772 Plasma waves and instabilities (2471)
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005