HR: 0800h
AN: P51B-1437    [Abstracts]
TI: Clouds of Neptune and Uranus: Implications for Entry Probes
AU: * Wong, A
EM: aswong@umich.edu
AF: Atmospheric, Oceanic and Space Sciences University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109-2143 United States
AU: Atreya, S K
EM: atreya@umich.edu
AF: Atmospheric, Oceanic and Space Sciences University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109-2143 United States
AB: Abundances of heavy elements below cloud levels provide critical constraints to the models of formation of giant planets and the origin of their atmospheres. In this study we present the results of an equilibrium cloud condensation model which calculates the bases and concentrations of methane ice, ammonia ice, ammonium hydrosulfide-solid, water ice, and aqueous-ammonia solution (``droplet'') clouds. Due to their similar p-T structures, the Neptune and Uranus results are similar. Based on the measured CH$_4$ mixing ratio, the C/H at Neptune is 30-50$\times$ solar, and 20-30$\times$ solar at Uranus. Assuming similar enhancement for the other condensibles, as expected from formation models, we find that the base of the droplet cloud is at the 370 bars for 30$\times$ solar, and at 500 bar for 50$\times$ solar cases. On the other hand, noble gases and H$_2$S can be accessed at much shallower levels, and still permit the retrieval of information critical to the formation of these planets and their atmospheres.
DE: 5707 Atmospheres--structure and dynamics
DE: 6207 Comparative planetology
DE: 6255 Neptune
DE: 6293 Uranus
DE: 0320 Cloud physics and chemistry
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting