Gravity wave heating and cooling in Jupiter's thermosphere

A numerical model to explore the possibility that the dissipation of two up ward propagating internal gravity waves, identified in the temperature meas urements of the Galileo Probe, provide the energy to maintain Jupiter's hig h thermospheric temperatures similar to 900 K is used. The propagation and dissipation of the gravity waves are simulated by a full-wave model that is used to calculate the thermal mean-state forcing. The observed temperature is the result of this forcing and other energy sources. The equation of he at transfer, including the effects of eddy and molecular thermal diffusion, is solved to provide the gravity wave contribution to the steady-state tem perature distribution. For the smallest values of eddy diffusion considered , the waves can heat the entire thermosphere, while for the largest values of eddy diffusion, the waves can cool the entire thermosphere. However, in all cases considered the net heating and cooling effects are not large, bei ng typically similar to 15-20 K or less. To the extent that the Galileo dat a characterize gravity waves in Jupiter's atmosphere, gravity wave dissipat ion is unlikely to be the source of energy maintaining Jupiter's high therm ospheric temperatures. Other waves not identified in the Galileo data or ot her energy sources must be responsible for heating the jovian thermosphere. We demonstrate that the viscous heating can only be calculated using the v iscous stress tensor, and that the use of the wave mechanical energy flux d ivergence for this purpose in previous studies is invalid. (C) 2000 Academi c Press.