HR: 13:55h
AN: P23C-02    [Abstracts]
TI: The Structure of Saturn's South Polar Vortex Determined by Cassini VIMS: Constraints on Winds and Horizontal and Vertical Cloud Distributions
AU: * Baines, K H
EM: blueskies4321@yahoo.com
AF: Jet Propulsion Laboratory/California Institute of Technology, M/S 183-601, 4800 Oak Grove Drive, Pasadena, CA 91109, United States
AU: Momary, T W
EM: momary@mail1.jpl.nasa.gov
AF: Jet Propulsion Laboratory/California Institute of Technology, M/S 183-601, 4800 Oak Grove Drive, Pasadena, CA 91109, United States
AU: Temma, T
EM: ttemma@scn1.jpl.nasa.gov
AF: Jet Propulsion Laboratory/California Institute of Technology, M/S 183-601, 4800 Oak Grove Drive, Pasadena, CA 91109, United States
AU: Roos-Serote, M
EM: planet.film@mac.com
AF: Observatorio Astronomico de Lisboa, Tapada Da Ajuda, Lisboa, 1349-018, Portugal
AU: Showman, A P
EM: showman@lpl.arizona.edu
AF: University of Arizona, 1629 E. Univ. Blvd, Tucson, AZ 85721, United States
AU: Atreya, S K
EM: atreya@umich.edu
AF: University of Michigan, 2455 Hayward Street, Ann Arbor, MI 4809, United States
AU: Brown, R H
AF: University of Arizona, 1629 E. Univ. Blvd, Tucson, AZ 85721, United States
AU: Buratti, B J
EM: bonnie.j.buratti@jpl.nasa.gov
AF: Jet Propulsion Laboratory/California Institute of Technology, M/S 183-601, 4800 Oak Grove Drive, Pasadena, CA 91109, United States
AU: Clark, R N
EM: rclark@usgs.gov
AF: US Geological Survey, Box 25046 Federal Center, Denver, CO 80225, United States
AU: Nicholson, P D
EM: nicholso@astro.cornell.edu
AF: Cornell University, Space Sciences Building, Ithaca, NY 14853, United States
AU: ScienceTeam, T C
AB: We present new imagery and quantitative results for wind and cloud structures in the south polar region of Saturn, obtained by Cassini/VIMS. A hurricane-like vortex feature is well observed in images obtained on October 11, 2006 and May 11, 2007, with a deep "eye" of cloud-free skies extending about 1 bar deeper than the surrounding ring of clouds. Winds measured in both reflected sunlight and in thermal radiation show comparable speeds throughout the region, suggesting little vertical wind shear over the 0.5-3-bar altitude range. Discrete clouds at 88 degrees S. planetographic latitude observed near the 0.5-2-bar level whip around the pole at speeds approaching 200 m/s. At greater latitudes, near the "eye" of the system, winds are much slower: about 45 m/s at 89.5 degrees S. latitude. From 88 degrees to 76 degrees S. latitude, the zonal wind structure as a function of radius/latitude is close to that expected for flows which maintain constant angular momentum. The picture that emerges is that this system is a giant polar vortex, spanning more than 15,000 km in diameter and at least 40 km in depth. Two distinct types of reflective, discrete clouds are observed interspersed throughout the region: bright clouds at continuum wavelengths from 0.6 to 2.7 microns characterized in our preliminary modeling as having imaginary indices of refraction near 0.002 at 0.7 micron, and spectrally dark clouds with twice that value. This suggests that two types of discrete clouds, colored by two distinct chemical compositions, reside in the south polar region. This is perhaps indicative of upwellings of materials from two distinct altitude regions in the depths of the south pole.
DE: 5700 PLANETARY SCIENCES: FLUID PLANETS
DE: 5704 Atmospheres (0343, 1060)
DE: 5739 Meteorology (3346)
DE: 5754 Polar regions
DE: 6275 Saturn
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting