HR: 1340h
AN: SM33A-1101    [Abstracts]
TI: Mass Density at Geosynchronous Orbit Inferred From Toroidal Alfven Frequencies
AU: * Denton, R E
EM: rdagu@rdenton.fastem.com
AF: Dartmouth College, Physics and Astronomy Department; 6127 Wilder Lab, Hanover, NH 03755, United States
AU: Takahashi, K
EM: kazue.takahashi@jhuapl.edu
AF: Applied Physics Laboratory, Johns Hopkins University; 11100 John Hopkins Road, Laurel, MD 20723-6099, United States
AB: Frequencies of the toroidal Alfven field line resonance mode can be used to infer magnetospheric mass density, a technique sometimes referred to as magnetoseismology. Geosynchronous orbit is an ideal location for this technique since a geosynchronous spacecraft approximately corotates with the plasma leading to a relatively stationary wave signal for Fourier analysis. Here we present results from magnetoseismology, with special emphasis on results at geosynchronous orbit. These include a solar cycle dependence with mass density higher at solar maximum, increased mass density with geomagnetic activity, a local time dependence with density higher in the afternoon local time sector, and a field line dependence which is relatively flat along the field line at morning local time, but peaked at the magnetic equator at afternoon local time, especially during geomagnetically active times.
DE: 2730 Magnetosphere: inner
DE: 2752 MHD waves and instabilities (2149, 6050, 7836)
DE: 2768 Plasmasphere
DE: 2794 Instruments and techniques
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting