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G. P. Smith, D. L. Huestis, D. Nash (SRI International)
A direct box model sensitivity analysis technique was applied to locations in a one-dimensional photochemical model of Jupiter's atmosphere to determine quantitatively the specific kinetic and photolysis steps that control various species concentrations. This procedure links measurements to the relevant chemistry, identifies rate parameters needing improved precision, suggests observations providing the most sensitive tests of the mechanism, and furnishes estimates for kinetic modeling errors. Results for all species, reactions, and locations are generated, and any chemical feedbacks or effects on precursors are automatically included.
More observations of diacetylene are identified, for example, as a good test of the photochemical mechanism from its many large output sensitivities. Altitude plots of H atom sensitivities illustrate the various photochemical regions. We also compare how the addition of rapid C atom reactions alters its sensitivities. Our results also point out sets of competitive reactions or reaction product ratios that are important in determining certain species concentrations. Many hydrogen atom addition reactions in hydrocarbons systems for example have addition, abstraction, and scission product channels to smaller fragments. The necessity of incorporating the proper pressure dependence of these rates is illustrated, including various recommendations derived from theoretical constructs.
Support provided by NSF Planetary Astronomy and NASA Planetary Atmospheres Programs. D. Nash participated in an NSF Research Experiences for Undergraduates Program at SRI. Thanks to Dr. Julianne Moses for providing the outputs and mechanism from her recent simulation of the Jovian atmosphere.
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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.