HR: 0800h
AN: SM41B-1186    [Abstracts]
TI: Multi-Spacecraft Observations of Chorus Dispersion and Source Location
AU: * Breneman, A W
EM: awbrenem@hotmail.com
AF: The University of Iowa, 203 Van Allen Hall, Iowa City, IA 52246 United States
AU: Kletzing, C A
EM: craig-kletzing@uiowa.edu
AF: The University of Iowa, 203 Van Allen Hall, Iowa City, IA 52246 United States
AU: Santolik, O
EM: os@matfyz.cz
AF: Charles University, Institute of Atmospheric Physics / CAS, Bocni II/1401, CZ-14131 Praha 4, Prague, 14131 Czech Republic
AU: Chum, J
EM: jch@ufa.cas.cz
AF: Charles University, Institute of Atmospheric Physics / CAS, Bocni II/1401, CZ-14131 Praha 4, Prague, 14131 Czech Republic
AB: Measurements from the Polar spacecraft have put an upper limit of a few thousand kilometers to the size of the magnetospheric chorus generation region along the magnetic field line in agreement with earlier theoretical estimates. Multipoint observations from the four Cluster spacecraft reveal that a single chorus wave packet can appear differently between spacecraft. One spacecraft observes a chorus element which is frequency shifted and time delayed relative to another. Since the dispersion relation for chorus waves is known, these differences provide a new opportunity to refine the parallel dimension of these source regions. A cross-correlation analysis is used to identify common chorus events between the Cluster spacecraft and to quantify their timing delays. The timing arrival differences and frequency accessibility are then simulated with a ray-tracing technique. Locations in the magnetosphere where the simulated frequency shift and time delay match the observed frequency shift and time delay for a single chorus event are determined as possible source regions. The ray-tracing technique and its limitations are shown through the simulation of a correlated event close to the generation region and an event further from the generation region. By studying several chorus events using these techniques a statistical analysis will be used to identify chorus source regions and determine the size of these source regions, thereby providing new insights into this wave mechanism.
DE: 2700 MAGNETOSPHERIC PHYSICS (6939)
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005