Interpretation of the zebra pattern in the Jovian kilometric radiation
The origin of a fine structure as quasi-harmonic parallel drifting stripes of enhanced brightness (zebra pattern) in the dynamic spectrum of Jovian kilometric radiation is discussed. A possible interpretation of the observed structure based on the effect of double plasma resonance (DPR) in the Jupiter magnetosphere is analyzed. It is shown that the observed features of the zebra pattern cannot be attributed to the DPR effect at electron cyclotron harmonics. The proposed scheme consists of excitation of ion cyclotron waves at the low hybrid frequency in the ion DPR regions and succeeding coalescence of these waves with a longitudinal wave at the upper hybrid frequency. The source parameters necessary for matching the expected and observed properties of the Jupiter zebra pattern are discussed.