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@comment{{This file has been generated by bib2bib 1.95}}
@comment{{Command line: /usr/bin/bib2bib --quiet -c 'not journal:"Discussions"' -c 'not journal:"Polymer Science"' -c '  author:"Hourdin"  ' -c year=1998 -c $type="ARTICLE" -oc lmd_Hourdin1998.txt -ob lmd_Hourdin1998.bib /home/WWW/LMD/public/}}
  author = {{Billebaud}, F. and {Rosenqvist}, J. and {Lellouch}, E. and 
	{Maillard}, J.-P. and {Encrenaz}, T. and {Hourdin}, F.},
  title = {{Observations of CO in the atmosphere of Mars in the (2-0) vibrational band at 2.35 microns}},
  journal = {\aap},
  year = 1998,
  month = may,
  volume = 333,
  pages = {1092-1099},
  abstract = {{Following our high-resolution infrared observations of CO in the
atmosphere of Mars in 1988 and 1989 at 4.7mu m (Billebaud et al., 1992),
we recorded new spectra of CO: one covering the whole disk of the planet
in 1990 and 4 spectra corresponding to 4 different locations on the
planet in 1991. All these spectra were recorded in the (2-0) vibrational
band at 2.35mu m. These data allow us to measure the CO abundance and to
search for possible middle-scale spatial variations of this abundance in
the case of the 1991 spectra. The CO mixing ratio derived from the 1990
data is in good agreement with the values we obtained in 1988 and 1989
(Billebaud et al., 1992), showing a great stability over a period of 3
years, with a value of the CO mixing ratio remaining in the range of
4.2-8.5 x 10(-4) . The results we obtained with the 1991 data also seem
to comfort the stability of the CO mixing ratio, although the possible
range is somewhat larger (5.5-11.5 x 10(-4) ). This common CO mixing
ratio range for the four locations on the planet then tends to exclude
the presence of any significant horizontal variations of the CO mixing
ratio, even if, from our data, we cannot firmly rule them out.
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Forget}, F. and {Hourdin}, F. and {Talagrand}, O.},
  title = {{CO $_{2}$Snowfall on Mars: Simulation with a General Circulation Model}},
  journal = {\icarus},
  year = 1998,
  month = feb,
  volume = 131,
  pages = {302-316},
  abstract = {{Although CO$_{2}$snowfall has never been directly observed on
Mars, it has been suggested that such precipitation may explain the
puzzling infrared measurements obtained by Mariner 9 and Viking during
the polar night in each hemisphere. The radiative effect of the snow
would strongly alter the radiative balance of the condensing polar caps
and thus the CO$_{2}$cycle and the global climate. We have
simulated this phenomenon with a general circulation model (GCM). For
that purpose, a new parameterization of CO$_{2}$condensation in
the atmosphere and on the ground has been developed, paying particular
attention to mass and energy conservation and allowing for the possible
sublimation of sedimenting CO$_{2}$ice particles. Atmospheric
condensation may result from radiative cooling on the one hand
(especially when the atmosphere is dust laden) and from adiabatic
cooling in upward motions on the other hand. This latter process can be
very efficient locally. On this basis, we have modeled the effect of the
CO$_{2}$snowfall on the infrared emission by decreasing the local
emissivities when atmospheric condensation was predicted by the model.
This parameterization is based on physical considerations (radiative
transfer through the CO$_{2}$ice particles, snow metamorphism on
the ground). Without tuning the model parameters, we have been able to
accurately reproduce the general behavior of the features observed by
Viking in the thermal infrared. These modeling results support the
CO$_{2}$snowfall scenario suggested from the observations.
Overall, this new parameterization, used in combination with the digital
terrain model topography and with allowance for a varying atmospheric
dust content, allows the GCM to simulate the
CO$_{2}$condensation-sublimation cycle realistically. In
particular, the seasonal variations of the surface pressure recorded by
the Viking Landers can now be reproduced without artificially decreasing
the condensation rate as was done in previous studies.
  doi = {10.1006/icar.1997.5874},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
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