The Cassini data presented in this view appear to confirm a region of warm
atmospheric descent into the eye of a hurricane-like storm locked to
Saturn's south pole. The view shows temperature data from the Cassini
spacecraft composite infrared spectrometer overlaid onto an image from the
imaging science subsystem wide-angle camera.
The composite infrared spectrometer data refer to a depth in Saturn's
upper stratosphere where the pressure is 0.5 millibars (324 kilometers
above the 1-bar level), a region higher than that imaged by the imaging
camera and visual and infrared spectrometer during the same observation
period. The composite infrared spectrometer data show a very small hot
spot over the pole, similar in size to the "eye" of the storm seen in the
imaging science subsystem images. See also PIA08332 and PIA08333 for related images.
The color scale at the bottom indicates the temperature in Kelvin
corresponding to the colors of the temperature map. Numbers on the grid
correspond to lines of latitude and longitude on the planet.
Infrared images taken through the Keck I telescope by ground-based
observers had previously shown the south polar spot to be warm. Cassini's
composite infrared spectrometer has confirmed this with higher resolution
temperature maps of the area (like the map displayed here) and sees a
temperature increase of about 2 Kelvin (4 degrees Fahrenheit) at the pole.
The temperatures are in the stratosphere and higher up than the clouds
seen by the Cassini imaging and visual and infrared mapping spectrometer
instruments, but they suggest that the atmosphere sinks over the south
pole. Because the pressure increases with depth, the descending atmosphere
compresses and heats up. The warmer temperatures over the south pole also
indicate that the vortex winds are decaying with height in the
stratosphere.
The descent implied by the temperatures nicely supports the lower cloud
altitudes observed by the imaging camera and visual and infrared
spectrometer instruments at the pole.
The image and atmospheric data were acquired on Oct. 11, 2006, when
Cassini was approximately 340,000 kilometers (210,000 miles) from Saturn.
The wide-angle camera image was taken using a spectral filter sensitive to
wavelengths of infrared light centered at 752 nanometers. The image has
been contrast enhanced using digital image processing techniques. The
unprocessed image shows an oblique view toward the pole, and was
reprojected to show the planet from a perspective directly over the south
pole. Scale in the original image was about 17 kilometers (11 miles) per
pixel.
The Cassini-Huygens mission is a cooperative project of NASA, the European
Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory,
a division of the California Institute of Technology in Pasadena, manages
the mission for NASA's Science Mission Directorate, Washington, D.C. The
Cassini orbiter and its two onboard cameras were designed, developed and
assembled at JPL. The imaging operations center is based at the Space
Science Institute in Boulder, Colo. The composite infrared spectrometer
team is based at NASA's Goddard Space Flight Center, Greenbelt, Md.
For more information about the Cassini-Huygens mission visit
http://saturn.jpl.nasa.gov/. The Cassini imaging team homepage
is at http://ciclops.org. The composite infrared spectrometer team
homepage is http://cirs.gsfc.nasa.gov/.