HR: 15:10h
AN: P23D-07 INVITED     [Abstracts]
TI: New Views of Saturn's Dynamic Atmosphere from Cassini ISS and VIMS
AU: * Vasavada, A R
EM: ashwin.r.vasavada@jpl.nasa.gov
AF: Jet Propulsion Laboratory, California Institute of Technology 4800 Oak Grove Drive, Pasadena, CA 91109
AU: Porco, C C
EM: carolyn@ciclops.org
AF: Cassini Imaging Central Laboratory for Operations, Space Science Institute 4750 Walnut Street, Suite 205, Boulder, CO 80301
AU: Baines, K H
EM: kevin.h.baines@jpl.nasa.gov
AF: Jet Propulsion Laboratory, California Institute of Technology 4800 Oak Grove Drive, Pasadena, CA 91109
AU: Del Genio, A D
EM: delgenio@giss.nasa.gov
AF: NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025
AU: Ingersoll, A P
EM: api@gps.caltech.edu
AF: Division of Geological and Planetary Sciences, California Institute of Technology 150-21, Pasadena, CA 91125
AU: West, R A
EM: robert.a.west@jpl.nasa.gov
AF: Jet Propulsion Laboratory, California Institute of Technology 4800 Oak Grove Drive, Pasadena, CA 91109
AU: Horst, S M
EM: horst@alumni.caltech.edu
AF: Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721
AB: Cassini's Imaging Science Subsystem (ISS) and Visual and Infrared Mapping Spectrometer (VIMS) have fundamentally improved our understanding of Saturn's atmospheric dynamics since the spacecraft approached Saturn in early 2004. Imaging by the ISS at visible and near-infrared wavelengths allows simultaneous studies of winds and vertically distinct clouds and hazes. Feature tracking on deeper-sounding (near-infrared continuum) images results in zonal wind speeds that differ only slightly from those measured by Voyager. Tracking on methane absorption-band images, which emphasize higher-altitude features, reveals vertical wind shear in the equatorial region. The eddy momentum flux has been measured and will be compared with recent ISS results from Jupiter. The morphology, location, behavior, and life cycle of atmospheric vortices have been documented on 8 months of regularly acquired images. Convective storms are observed to occur near 35S and are correlated with Saturn Electrostatic Discharge events. VIMS has produced the first measurements of zonal winds at the two-bar level, using 5.1-micron images, where upwelling thermal radiation dominates over reflected sunlight. Overlying clouds attenuate this radiation, allowing the clouds to be mapped on both the day and night sides. Tracking these backlit clouds enables the determination of winds at a relatively deep level in the atmosphere near the two-bar level near where relatively large particles (>~5 micron radius) reside within a major cloud layer, possibly composed of ammonium hydrosulfide. Comparison of these winds with those determined by tracking sunlit cloud features enables the estimation of vertical wind shears.
DE: 4490 Turbulence (3379, 4568, 7863)
DE: 5704 Atmospheres (0343, 1060)
DE: 6275 Saturn
SC: Planetary Sciences [P]
MN: Fall Meeting 2005