[PPS01-P07] Ion Scale Height Variability in Hisaki Io Torus Observations
Keywords:Jupiter, Io, plasma torus, magnetosphere , hisaki, ultraviolet
The Hisaki dataset presents the possibility of an unparalleled opportunity to study long-term and short-term variations in ion temperatures. The instrument is not designed to take images of specific emissions, but its large entrance slit accepts the full height and width of the torus. In the ideal case, each spectral emission feature would appear as an image of the torus at its appropriate position in the spectrum, creating an “overlapogram” (as did the Cassini UVIS instrument). In reality, the emissions are blurred due to instrumental resolution and aberrations, and multiple spectral feature overlap. Furthermore, the changing opening angle of the rotating torus adds a spurious apparent scale height variation which must be removed, with special attention to asymmetries introduced by Jupiter's changing tilt. With allowances for all these effects, we will report on our search for ion temperature variations during the first two years of Hisaki observations, and compare our results to a previous independent study by M. Shishido (M.S. thesis, U. Tohoku).