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JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 110,
E08001,
doi:10.1029/2005JE002411,
2005
Photochemistry and diffusion in Jupiter's stratosphere: Constraints from ISO observations and comparisons with other giant
planets
J. I. Moses
Lunar and Planetary Institute, Houston, Texas, USA
T. Fouchet
LESIA, Observatoire de Paris, Meudon, France Université Paris 6, Paris, France
B. Bézard
LESIA, Observatoire de Paris, Meudon, France
G. R. Gladstone
Space Sciences Department, Southwest Research Institute, San Antonio, Texas, USA
E. Lellouch
LESIA, Observatoire de Paris, Meudon, France
H. Feuchtgruber
Max-Planck-Institut für Extraterrestrische Physik, Garching, Germany
Abstract
We have developed a one-dimensional, diurnally averaged, photochemical model for Jupiter's stratosphere that couples photodissociation,
chemical kinetics, vertical diffusion, and radiative transport. The predictions regarding the abundances and vertical profiles
of hydrocarbon compounds are compared with observations from the Infrared Space Observatory (ISO) to better constrain the
atmospheric composition, to better define the eddy diffusion coefficient profile, and to better understand the chemical reaction
schemes that produce and destroy the observed constituents. From model-data comparisons we determine that the C2H6 mole fraction on Jupiter is (4.0 ± 1.0) × 10−6 at 3.5 mbar and (2.7 ± 0.7) × 10−6 at 7 mbar, and the C2H2 mole fraction is (1.4 ± 0.8) × 10−6 at 0.25 mbar and (1.5 ± 0.4) × 10−7 at 2 mbar. The column densities of CH3C2H and C6H6 are (1.5 ± 0.4) × 1015 cm−2 and (8.0 ± 2) × 1014 cm−2, respectively, above 30 mbar. Using identical reaction lists, we also have developed photochemical models for Saturn, Uranus,
and Neptune. Although the models provide good first-order predictions of hydrocarbon abundances on the giant planets, our
current chemical reaction schemes do not reproduce the relative abundances of C2H
x
hydrocarbons. Unsaturated hydrocarbons like C2H4 and C2H2 appear to be converted to saturated hydrocarbons like C2H6 more effectively on Jupiter than on the other giant planets, more effectively than is predicted by the models. Further progress
in our understanding of photochemistry at low temperatures and low pressures in hydrogen-dominated atmospheres hinges on the
acquisition of high-quality kinetics data.
Received 1
February
2005;
accepted 18
May
2005;
published 4
August
2005.
Keywords: diffusion;
Jupiter;
photochemistry.
Index Terms: 5709 Planetary Sciences: Fluid Planets: Composition (1060); 5704 Planetary Sciences: Fluid Planets: Atmospheres (0343, 1060); 6220 Planetary Sciences: Solar System Objects: Jupiter; 6275 Planetary Sciences: Solar System Objects: Saturn; 6255 Planetary Sciences: Solar System Objects: Neptune.
Read Full Article (file size: 2616179 bytes) Cited by
Citation: Moses, J. I., T. Fouchet, B. Bézard, G. R. Gladstone, E. Lellouch, and H. Feuchtgruber
(2005),
Photochemistry and diffusion in Jupiter's stratosphere: Constraints from ISO observations and comparisons with other giant
planets,
J. Geophys. Res.,
110,
E08001,
doi:10.1029/2005JE002411.
Copyright 2005 by the American Geophysical Union.
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