Variation of Highest Cutoff Frequency of the Io-controlled Jovian Decametric Radiation

Abstract

RECENTLY E. E. Baart, J. G. Greener and A. Wulff have made an investigation into the maximum cutoff frequency of the decametric radiation as related to Io λ III (1967)1/2 coordinates. They showed (unpublished work) that the highest cutoff frequency (∼ 40 MHz) is observed only when Io is above 230° Jovian longitude. (We use longitude system III as defined by Donivan and Carr1.) Most theories developed recently concerning the Jovian decametric radiation deal entirely with the effect of Io on the decametric radiation. To investigate this important aspect of maximum cutoff frequency variation, it was found necessary to make a distinction between Io-controlled radiation and that radiation over which Io has no control. Only with this distinction will a comparison between theoretical predictions and observations be relevant.