Saturn Does the Wave in Upper Atmosphere

http://www.jpl.nasa.gov/news/features.cfm?feature=1686

Saturn Does the Wave in Upper Atmosphere
Jet Propulsion Laboratory
May 07, 2008

Two decades of scrutinizing Saturn are finally paying off, as
scientists
have discovered a wave pattern, or oscillation, in Saturn's atmosphere
only visible from Earth every 15 years.

The discovery of the wave pattern is the result of a 22-year campaign
observing Saturn from Earth (the longest study of temperature outside
Earth ever recorded), and the Cassini spacecraft's observations of
temperature changes in the giant planet's atmosphere over time.

The Cassini infrared results, which appear in the same issue of Nature
as the data from the 22-year ground-based observing campaign, indicate
that Saturn's wave pattern is similar to a pattern found in Earth's
upper atmosphere. The earthly oscillation takes about two years. A
similar pattern on Jupiter takes more than four Earth years. The new
Saturn findings add a common link to the three planets.

Just as scientists have been studying climate changes in Earth's
atmosphere for long periods of time, NASA scientists have been
studying
changes in Saturn's atmosphere. Glenn Orton of NASA's Jet Propulsion
Laboratory in Pasadena, Calif., says patience is the key to studying
changes over the course of a Saturnian year, the equivalent of about
30
Earth years.

"You could only make this discovery by observing Saturn over a long
period of time," said Orton, lead author of the ground-based study.
"It's like putting together 22 years worth of puzzle pieces, collected
by a hugely rewarding collaboration of students and scientists from
around the world on various telescopes."

The wave pattern is called an atmospheric oscillation. It ripples back
and forth within Saturn's upper atmosphere. In this region,
temperatures
switch from one altitude to the next in a candy cane-like, striped,
hot-cold pattern. These varying temperatures force the wind in the
region to keep changing direction from east to west, jumping back and
forth. As a result, the entire region oscillates like a wave.

A "snapshot" of the hot-cold temperature patterns in Saturn's
atmosphere
was captured by the Cassini Composite Infrared Spectrometer. Along
with
Earth-based data, the "snapshot" also uncovered other interesting
phenomena. Among them: the temperature at Saturn's equator switches
from
hot to cold, and temperatures on either side of the equator switch
from
cold to hot every Saturn half-year.

Mike Flasar, co-author of the Cassini paper, and principal
investigator
for Cassini's Composite Infrared Spectrometer at NASA's Goddard Space
Flight Center, Greenbelt, Md., said that Cassini helped define this
oscillation in combination with the ground observation campaign.

"It's this great synergy of using ground-based data over time, and
then
getting up close and personal with the oscillation in Saturn's
atmosphere through Cassini," said Flasar. "Without Cassini, we might
never have seen the structure of the oscillation in detail."

Cassini scientists hope to find out why this phenomenon on Saturn
changes with the seasons, and why the temperature switchover happens
when the sun is directly over Saturn's equator.

More information on the Cassini-Huygens mission can be found at:
http://saturn.jpl.nasa.gov, and http://www.nasa.gov/cassini.

The Cassini-Huygens mission is a cooperative project of NASA, the
European Space Agency and the Italian Space Agency. JPL, a division of
the California Institute of Technology in Pasadena, manages the
Cassini
mission for NASA's Science Mission Directorate, Washington, D.C. The
Cassini orbiter was designed, developed and assembled at JPL. The
Composite Infrared Spectrometer team is based at NASA's Goddard Space
Flight Center, Greenbelt, Md.

------------------------------------------------------------------------

Written by Diya Chacko
Media Contact:
Diya Chacko/ Carolina Martinez
818-393-5464/354-9382

.

Relevant Pages