Large-scale energetic particle layers in the high latitude Jovian magnetosphere

This study presents an analysis of long lasting (∼2–3 h) energetic (≳60 keV) ion and (≳40 keV) electron events observed by the HISCALE instrumentation on board Ulysses in the high latitude Jovian magnetosphere. The high latitude events in the prenoon dayside (d 36–38, 1992) and the south duskside (d 40–43, 1992) magnetosphere are different from the magnetodisk plasma sheet events; they are characterized by: (a) a rigidity dependent flux dispersion, (b) softening of the spectrum of energetic ions and electrons at flux minima (and of low energy ions at flux maxima) and (c) proximity of the spacecraft to the high latitude magnetopause. The spectral index peaks which correspond to the high latitude particle events show a ∼10 h (or ∼5 h) periodicity and a phase shift of ∼7 h between the inbound and the outbound measurements. The HISCALE data are consistent with the existence of large scale layers of energetic ions and electrons in the high latitude Jovian magnetosphere. The proposed concept of the high latitude magnetospheric large scale energetic particle layers provide us with the possibility of a new synthesis of a variety of Jovian observations.