The Pioneer 10 radio occultation measurements of the ionosphere of Jupiter

Data from the Pioneer 10 radio occultation measurements are utilized to study the vertical electron number density distribution in the Jovian ionosphere. The immersion measurements were made at 26 North latitude in the late afternoon local time. The solar zenith angle in this region was 81 deg. Emersion measurements were made at 58 North latitude near the morning terminator where the solar zenith angle was 95 deg. The detectable portion of the Jovian ionosphere consists of a number of layers distributed over an altitude range of more than 3000 km. The maximum density appears to be on the order of 30,000 electrons per cu cm. Assuming that H(+) is the principal ion in the upper portion of the ionosphere yields a topside plasma temperature of 900 plus or minus 400 K.