37th DPS Meeting, 4-9 September 2005
Session 51 Titan II
Oral, Thursday, September 8, 2005, 2:00-3:50pm, Music Concert Hall

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[51.06] The Evolution of Titan's Mid-latitude Clouds

C. A. Griffith, P. Penteado (University of Arizona), K. Baines (JPL), P. Drossart (Observatoire de Paris), J. Barnes (University of Arizona), Cassini VIMS Team

Only two kinds of clouds have been seen on Titan: large storms in the south pole and long clouds at temperate southern latitudes. The latter clouds are mysterious because of their preponderance at the particular latitude of -40o and preference for 0o longitude, and their extended longitude coverage of as much as a thousand kilometers. Here we analyze measurements from the Cassini Visual Infrared Mapping Spectrometer (VIMS) and determine for the first time the evolution in height and thickness of clouds on Titan. Our analysis indicates that the temperate clouds possess vigorous centers that grow from the middle troposphere (~23 km) to the upper tropopause (44 km) with updraft speeds of several to ten of meters per second. The cloud tops generally dissipate or fall 10 km within the next half hour. These characteristics indicate that the clouds evolve convectively, dissipate through rain, and, over the next day, waft downwind to achieve their great longitude extents. While predominately at -40o latitude, we detect similar clouds at other latitudes. The characteristics of the mid-latitude clouds, we argue, suggest that they originate from circulation induced convergence in addition to a forcing at the surface that may be associated with the Saturn's tides, geology or surface composition.

This work is supported by NASA's Planetary Astronomy Program and the Cassini Mission

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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.