Europa and the Decametric Radiation from Jupiter

Abstract

DECAMETRIC radiation from Jupiter is known to be under the control of the satellite Io. Recently, Wilson, Warwick and Libby (preceding communication) studied a fifth source not controlled by Io which emits more than 50 per cent of the total decametric radiation¹. They used a two-parameter differential spectral analysis which produced contour maps of the probability of emission with respect to Jupiter's central meridian longitude (LCM) and the departure from superior geocentric conjunction (SGC) of each of the four inner satellites: Amalthea, Io, Europa and Ganymede. Plots in the Io–LCM domain show typical Io-related enhancements of the probability of emission and also an Io-independent emission component, denoted in the preceding communication by “fifth source”. Similar plots in the Europa–LCM domain show localized areas of enhancement which indicate the existence of Europa control of decametric emission. Several authors have tentatively confirmed a Europa effect^2–4. On the other hand, others find no evidence for the effect^5,6.