SATURNS IONOSPHERE - INFERRED ELECTRON-DENSITIES

During the two Voyager encounters with Saturn, radio bursts were detected that appear to have originated from atmospheric lightning storms. Although these bursts generally extended over frequencies from as low as 100 kHz to the upper detection limit of the instrument, 40 MHz, they often exhibited a sharp but variable low-frequency cutoff below which bursts were not detected. The variable low-frequency extent of these bursts is interpreted to be due to the refraction and reflection of the radio waves as they propagate through an ionosphere that varies with local time. Estimates of electron densities at a variety of latitude and local time locations are obtained. These compare well with the dawn and dusk densities measured by the Pioneer 11 and Voyager radio science investigations and with model predictions for dayside densities.