HR: 0800h
AN: P41A-0209    [Abstracts]
TI: Modeling Hydrocarbons in the Atmosphere of Neptune and Comparison with Spitzer Observations
AU: * Zhang, X
EM: xiz@gps.caltech.edu
AF: Division of Geological and Planetary Sciences, California Institute of Technology, MS 150- 21 1200E California Blvd., Pasadena, CA 91125, United States
AU: Yung, Y L
EM: yly@gps.caltech.edu
AF: Division of Geological and Planetary Sciences, California Institute of Technology, MS 150- 21 1200E California Blvd., Pasadena, CA 91125, United States
AU: Liang, M
EM: mcl@gps.caltech.edu
AF: Division of Geological and Planetary Sciences, California Institute of Technology, MS 150- 21 1200E California Blvd., Pasadena, CA 91125, United States
AU: Liang, M
EM: mcl@gps.caltech.edu
AF: Research Center for Environmental Changes, Academia Sinica, 128 Sec. 2, Academia Rd., Nankang, Taipei, 115, Taiwan
AU: Moses, J
EM: moses@lpi3.jsc.nasa.gov
AF: Lunar and Planetary Institute, 3600 Bay Area Blvd., Houston, TX 77058-1113, United States
AU: Meadows, V
EM: vsm@astro.washington.edu
AF: Department of Astronomy University of Washington, Box 351580, Seattle, WA 98195, United States
AU: Orton, G
EM: Glenn.S.Orton@jpl.nasa.gov
AF: Jet Propulsion Laboratory, M/S 169-237 4800 Oak Grove Drive, Pasadena, CA 91109, United States
AB: Recent observations made by the IRS instrument onboard Spitzer provide new constraints on the abundances of hydrocarbons in the atmosphere of Neptune. A one-dimensional, diurnally averaged photochemical model has been used to simulate the Spitzer results. We show that the molar fractions of complex hydrocarbons, such as benzene (C6H6), are extremely sensitive to the prescribed eddy diffusion profile, but simple hydrocarbons like ethane (C2H6) and acetylene (C2H2) are less sensitive to the eddy diffusivity. For example, reducing the eddy coefficients by a factor of 5 would enhance hydrocarbon abundances such as C4H2, CH3C2H, and C6H6 by more than an order of magnitude. In order to give the best fit to the methane data from Spitzer, we must enhance the concentration of methane at lower boundary over that given by Moses et al (2005). A sensitivity study with respect to the changes of eddy mixing, selected chemical reactions and CH4 concentration at the lower boundary will be presented.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0317 Chemical kinetic and photochemical properties
DE: 5405 Atmospheres (0343, 1060)
DE: 5704 Atmospheres (0343, 1060)
DE: 5709 Composition (1060)
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting