High color ratio and high temperature in Jupiter's auroral atmosphere

A high FUV color ratio usually implies that most of the energy of the impinging auroral particles is deposited below the methane homopause. In this region, the resulting auroral heating is efficiently balanced by the strong hydrocarbon cooling. Therefore, this auroral process cannot sustain the high temperature observed in the Jovian auroral atmosphere. This work is an attempt to remove the ambiguity between the high color ratios and high temperatures deduced from the HST data. In order to study this apparent contradiction, the two-stream energy deposition model described by Grodent et al. (2001) has been upgraded with a Joule heating module and an adiabatic cooling approximation. The most recent hydrocarbon auroral density profiles have been included. A new EUV-FUV spectral generator has been developed and allows one to consider new observational constrains, such as the very high H2 scale heights deduced from the Cassini-Jupiter flyby HST observations.