Jupiter's Massive Winds Likely Generated From Deep Inside ItsInterior, Scientists Report (Forwarded)

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November 10, 2005

Jupiter's Massive Winds Likely Generated From Deep Inside Its Interior,
Scientists Report

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 today 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.

IMAGE CAPTION:
[http://www.newsroom.ucla.edu/NewsRel...ages/6624a.jpg
(88KB)]
This image shows results from a computer simulation of Jupiter's winds.
The color contours show wind speed with red representing eastward flows
and blue representing westward flows. Credit: Dr. Moritz Heimpel,
University of Alberta, Department of Physics