24.11

Wave Heating in Jupiter's Thermosphere

Leslie A. Young, Roger V. Yelle (Boston University), Richard Young (NASA Ames Research Center), Alvin Seiff (San Jose State University Foundation), Donn B. Kirk (University of Oregon)

The Atmosphere Structure Instrument (ASI) on the Galileo probe detected wave-like temperature fluctuations superimposed on a 700 Kelvin temperature increase in Jupiter's thermosphere. These waves are simple in structure, are convectively stable, and are damped by molecular, not eddy, viscosity. This is in contrast with stratospheric fluctuations, also seen in the ASI profile, and first detected in ground-based stellar occultations; stratospheric fluctuations have a complex spectral distribution, and are probably caused by breaking gravity waves that are critically damped by eddy viscosity. The thermospheric waves are consistent with gravity waves that reach their maximum amplitudes at 430-710 km above the 1-bar level. This is where they deposit their energy, and the heating by these waves can explain the temperature increase measured by the probe.