FARADAY-EFFECT IN THE JOVIAN DECAMETRIC RADIATION OBSERVED WITH A NEWRADIOSPECTROGRAPH AT WAKKANAI

Dynamic spectrum observations of the Jovian decametric radiation (JDR) have been carried out since 1993 at the Wakkanai Radio Observatory us ing a new radiospectrograph system, which covers with a frequency rang e from 20 to 40 MHz. The Faraday effect in JDR spectra is analyzed for two kinds of JDR events; emissions from Io-related (Io-A) source and those from non Io-related source. A significant excess of the Faraday rotation to the terrestrial contribution is disclosed by the compariso n with satellite beacon measurements taken simultaneously at Wakkanai. This result suggests that the Faraday effect by the Jovian plasma can not be neglected for both Io-A and non Io-A emissions.