HR: 1340h
AN: SM13A-0321    [Abstracts]
TI: Non-Parametric Approarch for Global Plasmaspheric Electron Density Tomography using the Characteristics of Whistler Waves
AU: * Goto, Y
EM: ygotou@is.t.kanazawa-u.ac.jp
AF: Kanazawa Univ., Kakuma, Kanazawa, 920-1192 Japan
AU: Kasahara, Y
EM: kasahara@is.t.kanazawa-u.ac.jp
AF: Kanazawa Univ., Kakuma, Kanazawa, 920-1192 Japan
AU: Sato, T
EM: tsato@kuee.kyoto-u.ac.jp
AF: Kyoto Univ., Yoshida, Sakyo-ku, Kyoto, 606-8501 Japan
AB: The Earth's plasmasphere is investigated not only for scientific interests but also for engineering applications since the plasmaspheric plasma cannot be ignored for high-precision navigation and positioning from artificial satellites. The electron density in the plasmasphere is generally observed from spacecraft because the ionosphere disturbs us from direct observations from the ground. In the present study, we introduce an estimation method of the plasmaspheric electron density profile using whistler waves which are one of the most familiar VLF waves observed from satellites in the plasmasphere. While the propagation characteristics of ducted whistlers were used to acquire the signature of the plasmasphere, those of non-ducted ones were rarely used because of their complexity. The propagation characteristics of non-ducted whistlers cannot be calculated analytically but numerically. Recent advancement of computer technology made it possible to trace a few million of ray paths in a short time, and the initial ray parameters at wave sources are easily translated into those at observation points, which are a simple mapping. The estimation method is based on a model fitting in which an non-parametric model is used to represent the electron density profile like computer tomography in order not to deform the information of observed wave data. The wave normal directions and the spectrums of whistlers can be theoretically calculated for a given electron density profile by ray tracing. Comparing these theoretical values with observed ones, an electron density profile which is consistent to a given wave parameter set is obtained.
DE: 2768 Plasmasphere
DE: 6939 Magnetospheric physics (2700)
DE: 6969 Remote sensing
DE: 6982 Tomography and imaging (7270, 8180)
DE: 6984 Waves in plasma (7867)
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005