TRANSMISSION CHARACTERISTICS OF VLF ELF RADIO-WAVES THROUGH THE JOVIAN IONOSPHERE

The propagation characteristics of whistler-mode waves through the plausible profiles of the Jovian ionosphere have been investigated by means of full-wave numerical computations. There were three different profiles examined in detail: an irregular profile based on Pioneer measurements, a more-idealized smoother profile, and a smooth profile with a low-altitude ledge. The whistler transmission losses for the Pioneer profiles with several ledges are found to be extremely large in a wide frequency range from 1 to 10 kHz at both day and night, even at a high magnetic latitude. The latitudinal dependence of the transmission loss for the smooth electron density profiles corresponding approximately to the lower edge of the Pioneer profiles, is estimated such that the loss at magnetic latitude greater than 50-degrees is less than 10 dB at night and day. But the transmission loss exhibits a dramatic increase with the decrease in latitude from 30-degrees approximately 40-degrees, especially at higher frequency and at day. The presence of a possible ledge in the bottom ionosphere is found to result in an oscillatory behaviour of transmission loss due to the development of a standing wave pattern between relative density maxima. The possible utilization of these theoretical characteristics is suggested to study the coupling of lightning energy to whistlers in the Jovian magnetosphere and also lightning properties from the whistler observations by future deep spacecrafts.