Heating of Jupiter's Thermosphere by Dissipation of Gravity Waves Due to Molecular Viscosity and Heat Conduction

Abstract

Heating Jupiter's thermosphere by viscous dissipation of upward propagating gravity waves is evaluated with correct formulations of total energy conservation and the total wave induced vertical energy flux. In contrast to the results of L. A. Young et al. (1997, Science276, 108–111), our calculations, with their wave amplitudes and parameters, yield a maximum thermospheric temperature of T=380 K at 552 km above the 1-bar level in comparison to the Galileo probe inferred temperature of T=900 K and therefore gravity waves may not be solely responsible for the observed steep temperature gradient just above the homopause. The large sensible heat flux associated with dissipating gravity waves generates net heating of the lower regions and net cooling of the upper regions of wave dissipation due to energy redistribution. The transition from net heating to net cooling occurs at the level of constant wave amplitude. In regions of substantial wave dissipation the local cooling rate due to sensible heat flux divergence can exceed the local heating due to convergence of the Eliassen–Palm flux to produce (1) net cooling of and (2) a distinct temperature decrease (≈65 K) in the topside thermosphere. To simulate Jupiter's thermospheric temperature profile inferred from the Galileo probe data with (1) gravity wave heating only, (2) 100% conversion of wave energy to internal energy, and (3) radiative cooling by H+3 near-IR emission ∼0.1 erg cm−2 s−1, gravity waves must deposit their energy high in the thermosphere with peak heating occurring near ∼500 and ∼1000 km with near saturation amplitudes at very high altitudes (>1100 km).