The Winds of Jupiter
Most air travelers have experienced at least one uncomfortable episode of "clear-air turbulence". Meteorologists describe these gusty high-altitude "air pockets" as regions of low "Richardson number", a measure of the stability of the local atmosphere which depends on the competing effects of thermal layering and wind shear. Now three GISS researchers — Michael Allison, Anthony Del Genio, and Wei Zhou — have assembled evidence for a weakly stable, low Richardson number region in the vicinity of Jupiter's cloud deck. Their inference is based on the revealing shape of the stronger-poleward contours of Jupiter's equatorial jet stream, consistent with a zone of turbulent, well-mixed wind-swirls. Jupiter's atmosphere is convectively heated and mixed by the deep hot stove of its formative and continuing gravitational contraction. The well-mixed zone of weakly-stable winds may be a major conduit of the Jupiter heat engine, stretching across thousands of miles of cloudy atmosphere. On December 7, 1995, NASA's Galileo probe entered Jupiter's equatorial atmosphere, measuring winds, temperatures, sunlight, and cloud properties as it descended. According to Allison and his colleagues, the probe should have experienced considerable turbulence, swinging beneath its parachute. Careful study of the data (to be relayed to Earth in early 1996) should lend deeper insights into the windy meteorology of Jupiter.
Allison, M., A.D. Del Genio, and W. Zhou 1995. Richardson number constraints for the Jupiter and outer planet wind regime. Geophys. Res. Lett. 21, 2957-2960.
Please address all inquiries about this research to Dr. Michael Allison.