Models of the Jovian upper atmosphere

Journal Article · Tue May 01 04:00:00 EDT 1979 · Rev. Geophys. Space Phys.; (United States)

DOI:https://doi.org/10.1029/RG017i003p00388· OSTI ID:6216146

Atreya, S K; Donahue, T M

Recent developments in photochemical models of the upper atmosphere of Jupiter and Titan are reviewed. Measurements of the Jovian Lyman alpha airglow favor a homopause value of approximately 10/sup 7/ cm/sup 2/ s/sup 1/ for the eddy diffusion coeflicient. A relatively hot exosphere as implied by the electron density measurements results in an extended atmosphere of hydrogen. Larger than solar C/H and N/H ratios are obtained on reinterpretation of the sunlight reflected from Jupiter: and substantially lower ultraviolet photoabsorption cross sections measured for methane and ethane influence the distribution of CH/sub 4/, NH/sub 3/, and their photochemical products. Possible coupling between PH/sub 3/ and NH/sub 3/ may inhibit ultraviolet destruction of NH/sub 3/ on Jupiter. The red color of the Great Red Spot and other minor spots may be due to the presence of red phosphorus crystals formed after photolysis of PH/sub 3/. The detection of such gases as PH/sub 3/, GeH/sub 4/ and CO in the stratosphere of Jupiter gives an indication of the presence of thermochemical nonequilibrium processes, and a strong vertical mixing may be required to explain their large observed upper atmospheric abundances. This argument is further strengthened by a laboratory finding that C/sub 2/H/sub 2/ can efficiently scavenge photolysis products of PH/sub 3/. Other alternate mechanisms to account for the presence of CO in the stratosphere are the oxygen atom transfer from the Galilean satellites to Jupiter either by radial diffusion, or along magnetic flux tubes, or on ablation of meteoroidal material. Subsequent reactions of the thermal oxygen atoms with photolysis products of methane lead to the production of CO. Finally, the discussion of reducing atmospheres is extended to include Titan.

• Research Organization: Department of Atmospheric and Oceanic Science, Space Physics Research Laboratory, University of Michigan, Ann Arbor, Michigan 48109
• OSTI ID: 6216146
• Journal Information: Rev. Geophys. Space Phys.; (United States), Journal Name: Rev. Geophys. Space Phys.; (United States) Vol. 17:2; ISSN RGPSB
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics & Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALKANES
AMMONIA
ATMOSPHERES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMISTRY
CRYOGENIC FLUIDS
EARTH ATMOSPHERE
ELECTRON DENSITY
ELEMENTS
ETHANE
EXOSPHERE
FLUIDS
HYDRIDES
HYDROCARBONS
HYDROGEN
HYDROGEN COMPOUNDS
JUPITER PLANET
KINETICS
MAGNETIC FLUX
METHANE
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NONMETALS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOSPHINES
PHOSPHORUS
PHOSPHORUS COMPOUNDS
PHOTOCHEMISTRY
PLANETARY ATMOSPHERES
PLANETS
REACTION KINETICS
SATELLITES