HR: 0800h
AN: SM21A-0457    [Abstracts]
TI: Estimating magnetospheric densities using observations of the Alfven continuum
AU: Kabin, K
EM: kabin@phys.ualberta.ca
AF: University of Alberta, Department of Physics , Edmonton, AB T6G2J1 Canada
AU: * Rankin, R
EM: rankin@phys.ualberta.ca
AF: University of Alberta, Department of Physics , Edmonton, AB T6G2J1 Canada
AU: Mann, I R
EM: imann@space.ualberta.ca
AF: University of Alberta, Department of Physics , Edmonton, AB T6G2J1 Canada
AU: Dent, Z C
EM: zdent@phys.ualberta.ca
AF: University of Alberta, Department of Physics , Edmonton, AB T6G2J1 Canada
AB: Modern data analysis techniques allow the frequencies of standing shear Alfven waves (Alfven continuum) in the magnetosphere to be estimated almost routinely. These frequencies are primarily determined by two factors: the magnetic field intensity and density distribution along the length of geomagnetic magnetic field lines. We solve an eigenvalue problem to obtain the frequency of shear waves based on a general magnetic topology provided by the Tsyganenko magnetic field model and the global MHD model BATS- R-US. Together with the measured Alfven continuum frequencies, this technique is used to infer the magnetospheric plasma density over a range of local time. Our estimates are based on observations made under "typical" solar wind conditions when the empirical Tsyganenko model likely provides a good approximation for the magnetic field, as well as for extreme solar wind conditions (May 12, 1999, "the day Solar Wind disappeared") when global models may be expected to provide a more accurate representation of the magnetic field.
DE: 2730 Magnetosphere--inner
DE: 2731 Magnetosphere--outer
DE: 2753 Numerical modeling
DE: 2768 Plasmasphere
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting