Jovian thermal structure inferred from the energy degradation of auroral electrons

A one--dimensional model has been developed to investigate the links between auroral heat input and the atmospheric temperature and composition structure of Jupiter. Different energy distributions are used to evaluate the importance of the energy spectrum of the incident electrons for the thermal balance of Jupiter's auroral thermosphere. Radiative cooling by H_3(+) and hydrocarbon (CH_4, C_2H_2) and downward conduction are calculated to solve the heat conduction equation. The values of observable quantities such as the altitude of the H_2 emission peak, infrared (IR) and ultraviolet (UV) emissions and temperatures associated with H_2 and H_3(+) optical signatures are used to constrain the parameters of the auroral electron energy distributions. From these simulations, it appears that the precipitated auroral energy is not able to directly provide the necessary heat to balance the hydrocarbon cooling below the homopause. It is suggested however that the auroral upper stratosphere is warmer than the equatorial upper stratosphere measured by Galileo. A Maxwellian energy distribution with a total flux of 20 ergs cm(-2) s(-1) and a characteristic energy of 22 keV added to a soft Maxwellian component of 1 erg cm(-2) s(-1) and 350 eV produces results in good agreement with thermospheric observations.