@comment{{This file has been generated by bib2bib 1.97}}
@comment{{Command line: bib2bib --quiet -c year=2003 -c $type="ARTICLE" -oc pub2003.txt -ob pub2003.bib}}
  author = {{Luz}, D. and {Hourdin}, F. and {Rannou}, P. and {Lebonnois}, S.
  title = {{Latitudinal transport by barotropic waves in Titan's stratosphere.. II. Results from a coupled dynamics-microphysics-photochemistry GCM}},
  journal = {\icarus},
  year = 2003,
  volume = 166,
  pages = {343-358},
  abstract = {{We present a 2D general circulation model of Titan's atmosphere,
coupling axisymmetric dynamics with haze microphysics, a simplified
photochemistry and eddy mixing. We develop a parameterization of
latitudinal eddy mixing by barotropic waves based on a shallow-water,
longitude-latitude model. The parameterization acts locally and in real
time both on passive tracers and momentum. The mixing coefficient varies
exponentially with a measure of the barotropic instability of the mean
zonal flow. The coupled GCM approximately reproduces the Voyager
temperature measurements and the latitudinal contrasts in the
distributions of HCN and C $_{2}$H $_{2}$, as well as the
main features of the zonal wind retrieved from the 1989 stellar
occultation. Wind velocities are consistent with the observed reversal
time of the North-South albedo asymmetry of 5 terrestrial years. Model
results support the hypothesis of a non-uniform distribution of infrared
opacity as the cause of the Voyager temperature asymmetry. Transport by
the mean meridional circulation, combined with polar vortex isolation
may be at the origin of the latitudinal contrasts of trace species, with
eddy mixing remaining restricted to low latitudes most of the Titan
year. We interpret the contrasts as a signature of non-axisymmetric
  doi = {10.1016/j.icarus.2003.08.014},
  adsurl = {},
  localpdf = {REF/2003Icar..166..343L.pdf},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Lebonnois}, S. and {Hourdin}, F. and {Rannou}, P. and {Luz}, D. and 
	{Toublanc}, D.},
  title = {{Impact of the seasonal variations of composition on the temperature field of Titan's stratosphere}},
  journal = {\icarus},
  year = 2003,
  volume = 163,
  pages = {164-174},
  abstract = {{We investigate the role of seasonal variations of Titan's stratospheric
composition on the temperature. We use a general circulation model
coupled with idealized chemical tracers that reproduce variations of
ethane (C $_{2}$H $_{6}$), acetylene (C $_{2}$H
$_{2}$), and hydrogen cyanide (HCN). Enhancement of the mole
fractions of these compounds, at high latitudes in the winter hemisphere
relative to their equatorial values, induces a relative decrease in
temperature above approximately 0.2 mbar, with a peak amplitude around
-20 K, and a relative increase in temperature below, around 1 mbar, with
a peak amplitude around +7 K. These thermal effects are mainly due to
the variations of the cooling to space induced by the varying
distributions. The ethane, acetylene, and hydrogen cyanide variations
affect the cooling rates in a similar way, with the dominant effect
being due to ethane, though its latitudinal variations are small.
  doi = {10.1016/S0019-1035(03)00074-5},
  adsurl = {},
  localpdf = {REF/2003Icar..163..164L.pdf},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Lebonnois}, S. and {Bakes}, E.~L.~O. and {McKay}, C.~P.
  title = {{Atomic and molecular hydrogen budget in Titan's atmosphere}},
  journal = {\icarus},
  year = 2003,
  volume = 161,
  pages = {474-485},
  abstract = {{Using a one-dimensional model, we investigate the hydrogen budget and
escape to space in Titan's atmosphere. Our goal is to study in detail
the distributions and fluxes of atomic and molecular hydrogen in the
model, while identifying sources of qualitative and quantitative
uncertainties. Our study confirms that the escape of atomic and
molecular hydrogen to space is limited by the diffusion through the
homopause level. The H distribution and flux inside the atmosphere are
very sensitive to the eddy diffusion coefficient used above altitude 600
km. We chose a high value of this coefficient 1 {\times} 10 $^{8}$
cm $^{2}$ s $^{-1}$ and a homopause level around altitude
900 km. We find that H flows down significantly from the production
region above 500 km to the region [300-500] km, where it recombines into
H $_{2}$. Production of both H and H $_{2}$ also occurs in
the stratosphere, mostly from photodissociation of acetylene. The only
available observational data to be compared are the escape rate of H
deduced from Pioneer 11 and IUE observations of the H torus 1-3 {\times}
10 $^{9}$ cm $^{-2}$ s $^{-1}$ and the latest
retrieved value of the H $_{2}$ mole fraction in the stratosphere:
(1.1 {\plusmn} 0.1) {\times} 10 $^{-3}$. Our results for both of
these values are at least 50-100\% higher, though the uncertainties
within the chemical schemes and other aspects of the model are large.
The chemical conversion from H to H $_{2}$ is essentially done
through catalytic cycles using acetylene and diacetylene. We have
studied the role of this diacetylene cycle, for which the associated
reaction rates are poorly known. We find that it mostly affects C
$_{4}$ species and benzene in the lower atmosphere, rather than
the H profile and the hydrogen budget. We have introduced the
heterogenous recombination of hydrogen on the surface of aerosol
particles in the stratosphere, and this appears to be a significant
process, comparable to the chemical processes. It has a major influence
on the H distribution, and consequently on several other species,
especially C $_{3}$H $_{4}$, C $_{4}$H $_{2}$
and C $_{6}$H $_{6}$. Therefore, this heterogenous process
should be taken into account when trying to understand the stratospheric
distribution of these hydrocarbons.
  doi = {10.1016/S0019-1035(02)00039-8},
  adsurl = {},
  localpdf = {REF/2003Icar..161..474L.pdf},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Bakes}, E.~L.~O. and {Lebonnois}, S. and {Bauschlicher}, C.~W. and 
	{McKay}, C.~P.},
  title = {{The role of submicrometer aerosols and macromolecules in H $_{2}$ formation in the titan haze}},
  journal = {\icarus},
  year = 2003,
  volume = 161,
  pages = {468-473},
  abstract = {{Previous studies of the photochemistry of small molecules in Titan's
atmosphere found it difficult to have hydrogen atoms removed at a rate
sufficient to explain the observed abundance of unsaturated
hydrocarbons. One qualitative explanation of the discrepancy nominated
catalytic aerosol surface chemistry as an efficient sink of hydrogen
atoms, although no quantitative study of this mechanism was attempted.
In this paper, we quantify how haze aerosols and macromolecules may
efficiently catalyze the formation of hydrogen atoms into H
$_{2}$. We describe the prompt reaction model for the formation of
H $_{2}$ on aerosol surfaces and compare this with the catalytic
formation of H $_{2}$ using negatively charged hydrogenated
aromatic macromolecules. We conclude that the PRM is an efficient
mechanism for the removal of hydrogen atoms from the atmosphere to form
H $_{2}$ with a peak formation rate of {\tilde} 70 cm $^{-3}$
s $^{-1}$ at 420 km. We also conclude that catalytic H
$_{2}$ formation via hydrogenated anionic macromolecules is viable
but much less productive (a maximum of {\tilde} 0.1 cm $^{-3}$ s
$^{-1}$ at 210 km) than microphysical aerosols.
  doi = {10.1016/S0019-1035(02)00040-4},
  adsurl = {},
  localpdf = {REF/2003Icar..161..468B.pdf},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}