A new computer model indicates Jupiter's massive winds are generated from deep within the giant planet's interior, a UCLA scientist and international colleagues report in the journal Nature.
Jupiter's powerful winds are very different from those on Earth. They continually circle the planet, and have changed very little in the 300 years that scientists have studied them. Massive east-west winds in Jupiter's equatorial region reach approximately 340 miles per hour -- twice as rapid as winds generated by strong hurricanes on Earth. At higher latitudes, the wind pattern switches to alternating jets that race around the planet.
No one has been able to explain why the winds are so constant or what generates them -- but that may change.
"Our model suggests convection driven by deep internal heat sources power Jupiter's surface winds," said Jonathan Aurnou, UCLA assistant professor of planetary physics. "The model provides a possible answer to why the winds are so stable for centuries. Jupiter's surface is the tail; the dog is the hot interior of the planet.
"On Earth," Aurnou said, "we get strong changes in wind patterns every season. On Jupiter, there is almost no variation. There are changing cloud structures, but the large-scale winds remain essentially constant."
The researchers identified key ingredients that explain Jupiter's "super winds" and factored those into their model. Aurnou's colleagues are Moritz Heimpel, assistant professor of physics at the University of Alberta in Edmonton, and Johannes Wicht at the Max Planck Institute for Solar System Research in Germany.
Aurnou, Heimpel and Wicht created the first three-dimensional computer model that generates both a large eastward equatorial jet and smaller alternating jets at higher latitudes. In a rapidly rotating shell of fluid, they modeled thermally driven convection, which is what drives motion in a boiling pot.
"Three critical ingredients are the correct geometry, turbulent convection and rapid rotation, and our model contains all three elements," said Aurnou, a faculty member in UCLA's Department of Earth and Space Sciences. "When you include all those, that gives us the right recipe. In the future, we'll refine our model by adding even more ingredients."
Jupiter's radius is more than 11 times the radius of Earth. A tremendous amount of heat comes from the interior.
"The heat from Jupiter's interior is comparable to the heat the planet receives from the sun," Aurnou said.
The model suggests three-dimensional convection in Jupiter's deep atmosphere is likely driving the zonal flows, Aurnou said.
Jupiter's interior is made primarily of compressed hydrogen and helium, and a giant plasma.
Aurnou will continue to study Jupiter's strong winds, as well as those on Saturn, Uranus and Neptune.
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