Electron Densities in Jupiter's Magnetosphere Determined from Voyager and Galileo Plasma Wave Spectra

An electron plasma density data set for Jupiter's outer magnetosphere has been created through the interpretation of wideband measurements of low-frequency radio and plasma waves obtained by Voyagers 1 and 2 during their 1979 flybys. The spectra exhibit wave phenomena including continuum radiation, Z mode emissions, and whistler mode waves. Using cold plasma theory, electron densities were calculated from the identification of the cutoffs and resonances of these wave phenomena, including the electron plasma frequency, R = 0 cutoff, L = 0 cutoff, and upper hybrid resonance frequency. Densities were calculated for regions in the outer magnetosphere which were inside (outside) the plasma sheet where the plasma frequency is above (below) the electron cyclotron frequency. We now include observations from the Galileo orbital tour. These observations provide more comprehensive coverage of the magnetosphere, although there are times in the lobe when an unambiguous determination of the cutoff is not possible. In addition to using similar techniques as described above to determine outer magnetospheric densities, the Galileo wave measurements also include measurements of the upper hybrid resonance band in the inner magnetosphere.