PROPAGATION CHARACTERISTICS OF WHISTLER WAVES IN THE JOVIAN IONOSPHERE AND MAGNETOSPHERE

The purpose of this paper is to carry out extensive reexamination of the propagation characteristics of unducted whistlers in the Jovian magnetosphere, In addition to the previous work on the dispersion of whistlers, our emphasis is placed on the detailed study of their amplitude variations in order to investigate the plasma structure of the magnetosphere and characteristics of causative lightlling discharges, The two-dimensional ray-tracing computations are used as before to investigate magnetospheric whistler propagation paths, but with the first attempt of estimating the whole attenuation factors (polarization effect, focusing/defocusing and interactive damping (Landau and cyclotron)). The total attenuation due to three effects is estimated, which is compared with the amplitude of whistlers observed by the Voyager spacecraft, The following conclusions are reached. (1) Some bias in magnetospheric plasma density is required to explain the high-frequency cutoff of whistlers: (2) the magnetospheric temperature is about 20 eV for the interpretation of low-frequency cutoff of whistlers, and (3) estimated total radiated power per flash is about 4.5 x 10(6) W(0 similar to 20 kHz) on the assumption of unducted propagation and nearly the same even in the case of ducted propagation.