抄録
A three dimensional (3-D) ray tracing technique for whistler mode signals in the earth magnetosphere using a non-dipolar geomagnetic field model is investigated. A difficulty arising from the adoption of a general field model in ray tracing is that field line tracing is additionally required at every step of the calculation. This is because the plasma density profile such as the diffusive equilibrium model are defined along a geomagnetic field line which cannot be analytically determined in the general field model. To substantially reduce the computer time a minimum number of field line tracing are made in advance, and in the course of ray tracing some interpolation is utilized. The error arising from such interpolations is checked and is found to be insignificant. Some examples of ray tracing are shown. The ray path of 5kHz signals starting from the bottom of the ionosphere of the Siple (64.9°S, 7.5°W in geomagnetic coordinates) meridian is found to deviate eastward by about 15° at the apex.
