DPS 35th Meeting, 1-6 September 2003
Session 40. Outer Planets/Gas Giants IV
Poster, Highlighted on, Friday, September 5, 2003, 3:30-6:00pm, Sierra Ballroom I-II

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[40.17] Ionospheric Effects at Saturn Caused by Ring-Shadowing of Sunlight

L. Moore, M. Mendillo (Boston University), I. Mueller-Wodarg (Imperial College)

A time-dependent photochemical model of Saturnís ionosphere has been developed as an intermediate step towards a fully coupled Saturn-Thermosphere-Ionosphere-Model (STIM). A global circulation model (GCM) of the thermosphere provides the latitude and local time dependent neutral atmosphere. Voyager UVS occultation data are adapted to model the UV optical depth radial profile of the rings. Shadowing from the rings leads to attenuation of solar flux, the magnitude and latitudinal structure of which depends on season. During solstice, the season for Cassiniís encounter with Saturn, attenuation has a maximum of two orders of magnitude, causing a reduction in modeled electron densities over mid-latitude locations by as much as a factor of five.

This research is supported by the NASA Planetary Atmospheres Program.

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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.