37th DPS Meeting, 4-9 September 2005
Session 30 Outer Planets
Poster, Tuesday, September 6, 2005, 6:00-7:15pm, Music Lecture Room 5

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[30.16] Time Variation of Hydrocarbon Abundances on Uranus and Neptune: Predictions From a 1-D Model

J. I. Moses (LPI), R. D. Naphas (Embry-Riddle), T. K. Greathouse (LPI)

To evaluate the necessity of including meridional transport in photochemical models of Uranus and Neptune, we have developed a realistic one-dimensional model of stratospheric photochemistry that accounts for variations in ultraviolet flux due to orbital position, solar-cycle variations, and seasons. Uranus, with its very high obliquity and weak vertical mixing (believed to be due to its weak internal heat source), responds differently to seasonal variations than Neptune. However, hydrocarbon chemistry on both planets changes measurably with latitude and season. We will discuss the differences in photochemistry on the two planets, and compare the results with various observations. Predictions regarding the latitude and time dependence of hydrocarbon abundances and infrared spectra will be presented to aid in the analysis of present and near-future infrared observations from ground-based telescopes and the Spitzer Space Telescope. Implications for atmospheric transport (meridional and vertical) as well as possible variations in the vertical eddy diffusion coefficient with time on Uranus will be discussed.

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