@comment{{This file has been generated by bib2bib 1.94}}
@comment{{Command line: /usr/bin/bib2bib --quiet -c 'not journal:"Discussions"' -c year=2011 -c $type="ARTICLE" -oc pub2011.txt -ob pub2011.bib}}
  author = {{Madeleine}, J.-B. and {Forget}, F. and {Millour}, E. and {Montabone}, L. and 
	{Wolff}, M.~J.},
  title = {{Revisiting the radiative impact of dust on Mars using the LMD Global Climate Model}},
  journal = {Journal of Geophysical Research (Planets)},
  keywords = {Hydrology: Model calibration (3333), Atmospheric Processes: Clouds and aerosols, Atmospheric Processes: Global climate models (1626, 4928), Atmospheric Processes: Radiative processes, Planetary Sciences: Solar System Objects: Mars},
  year = 2011,
  volume = 116,
  number = e15,
  eid = {E11010},
  pages = {E11010},
  abstract = {{Airborne dust is the main driver of Martian atmospheric temperature, and
accurately accounting for its radiative effect in Global Climate Models
(GCMs) is essential. This requires the modeling of the dust distribution
and radiative properties, and when trying to simulate the true climate
variability, the use of the observed dust column opacity to guide the
model. A recurrent problem has been the inability of Mars GCMs to
predict realistic temperatures while using both the observed dust
radiative properties and column opacity. One would have to drive the
model with a tuned opacity to reach an agreement with the observations,
thereby losing its self-consistency. In this paper, we show that using
the most recently derived dust radiative properties in the LMD
(Laboratoire de Météorologie Dynamique) GCM solves this
problem, which was mainly due to the underestimation of the dust single
scattering albedo in the solar domain. However, an overall warm
temperature bias remains above the 1 hPa pressure level. We therefore
refine the model by implementing a {\ldquo}semi-interactive{\rdquo} dust
transport scheme which is coupled to the radiative transfer
calculations. This scheme allows a better representation of the dust
layer depth in the model and thereby removes the remaining warm bias.
The LMD/GCM is now able to predict accurate temperatures without any
tuning of the dust opacity used to guide the model. Remaining
discrepancies are discussed, and seem to be primarily due to the neglect
of the radiative effect of water-ice clouds, and secondarily to
persisting uncertainties in the dust spatial distribution.
  doi = {10.1029/2011JE003855},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Kerber}, L. and {Head}, J.~W. and {Madeleine}, J.-B. and {Forget}, F. and 
	{Wilson}, L.},
  title = {{The dispersal of pyroclasts from Apollinaris Patera, Mars: Implications for the origin of the Medusae Fossae Formation}},
  journal = {\icarus},
  year = 2011,
  volume = 216,
  pages = {212-220},
  abstract = {{The Medusae Fossae Formation (MFF) has long been thought to be of
Amazonian age, but recent studies propose that a significant part of its
emplacement occurred in the Hesperian and that many of the Amazonian
ages represent modification (erosional and redepositional) ages. On the
basis of the new formational age, we assess the hypothesis that
explosive eruptions from Apollinaris Patera might have been the source
of the Medusae Fossae Formation. In order to assess the likelihood of
this hypothesis, we examine stratigraphic relationships between
Apollinaris Patera and the MFF and analyze the relief of the MFF using
topographic data. We predict the areal distribution of tephra erupted
from Apollinaris Patera using a Mars Global Circulation Model (GCM)
combined with a semi-analytical explosive eruption model for Mars, and
compare this with the distribution of the MFF. We conclude that
Apollinaris Patera could have been responsible for the emplacement of
the Medusae Fossae Formation.
  doi = {10.1016/j.icarus.2011.07.035},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Fastook}, J.~L. and {Head}, J.~W. and {Forget}, F. and {Madeleine}, J.-B. and 
	{Marchant}, D.~R.},
  title = {{Evidence for Amazonian northern mid-latitude regional glacial landsystems on Mars: Glacial flow models using GCM-driven climate results and comparisons to geological observations}},
  journal = {\icarus},
  year = 2011,
  volume = 216,
  pages = {23-39},
  abstract = {{A fretted valley system on Mars located at the northern mid-latitude
dichotomy boundary contains lineated valley fill (LVF) with extensive
flow-like features interpreted to be glacial in origin. We have modeled
this deposit using glacial flow models linked to atmospheric general
circulation models (GCM) for conditions consistent with the deposition
of snow and ice in amounts sufficient to explain the interpreted
glaciation. In the first glacial flow model simulation, sources were
modeled in the alcoves only and were found to be consistent with the
alpine valley glaciation interpretation for various environments of flow
in the system. These results supported the interpretation of the
observed LVF deposits as resulting from initial ice accumulation in the
alcoves, accompanied by debris cover that led to advancing alpine
glacial landsystems to the extent observed today, with preservation of
their flow texture and the underlying ice during downwasting in the
waning stages of glaciation. In the second glacial flow model
simulation, the regional accumulation patterns predicted by a GCM linked
to simulation of a glacial period were used. This glacial flow model
simulation produced a much wider region of thick ice accumulation, and
significant glaciation on the plateaus and in the regional plains
surrounding the dichotomy boundary. Deglaciation produced decreasing ice
thicknesses, with flow centered on the fretted valleys. As plateaus lost
ice, scarps and cliffs of the valley and dichotomy boundary walls were
exposed, providing considerable potential for the production of a rock
debris cover that could preserve the underlying ice and the surface flow
patterns seen today. In this model, the lineated valley fill and lobate
debris aprons were the product of final retreat and downwasting of a
much larger, regional glacial landsystem, rather than representing the
maximum extent of an alpine valley glacial landsystem. These results
favor the interpretation that periods of mid-latitude glaciation were
characterized by extensive plateau and plains ice cover, rather than
being restricted to alcoves and adjacent valleys, and that the observed
lineated valley fill and lobate debris aprons represent debris-covered
residual remnants of a once more extensive glaciation.
  doi = {10.1016/j.icarus.2011.07.018},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Gonz{\'a}lez-Galindo}, F. and {M{\"a}{\"a}tt{\"a}nen}, A. and 
	{Forget}, F. and {Spiga}, A.},
  title = {{The martian mesosphere as revealed by CO $_{2}$ cloud observations and General Circulation Modeling}},
  journal = {\icarus},
  year = 2011,
  volume = 216,
  pages = {10-22},
  abstract = {{Different missions have observed mesospheric clouds on Mars in the last
years. The presence of these clouds implies, among other conditions,
mesospheric temperatures below CO $_{2}$ condensation temperature.
We use a General Circulation Model to study the mesospheric temperatures
and compare the observed distribution of the mesospheric clouds and the
predicted climatology of mesospheric temperatures. Although the model
does not usually predict temperatures below condensation for daytime
conditions, in some regions the predicted temperatures are close enough
to condensation that perturbations caused by small scale processes could
produce local excursions below condensation. The location and time of
the lowest temperatures predicted by the GCM correspond to a first order
with the two observed populations of mesospheric clouds: equatorial
clouds observed before and after the Northern summer solstice, and
mid-latitude clouds observed around the Northern winter solstice. For
the equatorial clouds season, the model predicts temperatures close to
condensation at the longitude, latitude, altitude and local time where
they have been observed. We find that the diurnal migrating thermal tide
and non-migrating tides are at the root of the spatial confinement of
the equatorial clouds. For the mid-latitude clouds season, the
temperatures predicted by the model at the location of the observed
clouds is too high. Stereo observations by two different instruments
allow for the determination of the zonal speed of these clouds producing
a rare dataset of mesospheric winds. We compare the mesospheric zonal
winds predicted by the model with these observations, finding a good
agreement, although in some cases the observed variability exceeds that
predicted by the model.
  doi = {10.1016/j.icarus.2011.08.006},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Chaufray}, J.-Y. and {Retherford}, K.~D. and {Horvath}, D.~G. and 
	{Bertaux}, J.-L. and {Forget}, F. and {Leblanc}, F.},
  title = {{The density of the upper martian atmosphere measured by Lyman-{$\alpha$} absorption with Mars Express SPICAM}},
  journal = {\icarus},
  year = 2011,
  volume = 215,
  pages = {522-525},
  abstract = {{Absorption of interplanetary Lyman-{$\alpha$} emission by Mars' nightside
lower thermosphere was observed by Mars Express Spectrometer for
Investigation of Characteristics of the Atmosphere of Mars (SPICAM), and
is analyzed to derive the CO $_{2}$ density at 110 km during a
martian year. The observed density seasonal variability is consistent
with recent observations obtained by stellar occultations, proving that
this method, though not as accurate as stellar occultations could be
used complementary to them to characterize large variations of
thermospheric density on Mars and provide a better spatial coverage by
Lyman-{$\alpha$} imagery.
  doi = {10.1016/j.icarus.2011.07.025},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Maltagliati}, L. and {Montmessin}, F. and {Fedorova}, A. and 
	{Korablev}, O. and {Forget}, F. and {Bertaux}, J.-L.},
  title = {{Evidence of Water Vapor in Excess of Saturation in the Atmosphere of Mars}},
  journal = {Science},
  year = 2011,
  volume = 333,
  pages = {1868},
  abstract = {{The vertical distribution of water vapor is key to the study of
Mars{\rsquo} hydrological cycle. To date, it has been explored mainly
through global climate models because of a lack of direct measurements.
However, these models assume the absence of supersaturation in the
atmosphere of Mars. Here, we report observations made using the SPICAM
(Spectroscopy for the Investigation of the Characteristics of the
Atmosphere of Mars) instrument onboard Mars Express that provide
evidence of the frequent presence of water vapor in excess of
saturation, by an amount far surpassing that encountered in
Earth{\rsquo}s atmosphere. This result contradicts the widespread
assumption that atmospheric water on Mars cannot exist in a
supersaturated state, directly affecting our long-term representation of
water transport, accumulation, escape, and chemistry on a global scale.
  doi = {10.1126/science.1207957},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Petrosyan}, A. and {Galperin}, B. and {Larsen}, S.~E. and {Lewis}, S.~R. and 
	{M{\"a}{\"a}tt{\"a}nen}, A. and {Read}, P.~L. and {Renno}, N. and 
	{Rogberg}, L.~P.~H.~T. and {Savij{\"a}rvi}, H. and {Siili}, T. and 
	{Spiga}, A. and {Toigo}, A. and {V{\'a}zquez}, L.},
  title = {{The Martian Atmospheric Boundary Layer}},
  journal = {Reviews of Geophysics},
  keywords = {Atmospheric Composition and Structure: Planetary atmospheres (5210, 5405, 5704), Atmospheric Processes: Boundary layer processes, Atmospheric Processes: Land/atmosphere interactions (1218, 1631, 1843, 4301), Atmospheric Processes: Mesoscale meteorology, Planetary Sciences: Solid Surface Planets: Atmospheres (0343, 1060)},
  year = 2011,
  volume = 49,
  eid = {RG3005},
  pages = {RG3005},
  abstract = {{The planetary boundary layer (PBL) represents the part of the atmosphere
that is strongly influenced by the presence of the underlying surface
and mediates the key interactions between the atmosphere and the
surface. On Mars, this represents the lowest 10 km of the atmosphere
during the daytime. This portion of the atmosphere is extremely
important, both scientifically and operationally, because it is the
region within which surface lander spacecraft must operate and also
determines exchanges of heat, momentum, dust, water, and other tracers
between surface and subsurface reservoirs and the free atmosphere. To
date, this region of the atmosphere has been studied directly, by
instrumented lander spacecraft, and from orbital remote sensing, though
not to the extent that is necessary to fully constrain its character and
behavior. Current data strongly suggest that as for the Earth's PBL,
classical Monin-Obukhov similarity theory applies reasonably well to the
Martian PBL under most conditions, though with some intriguing
differences relating to the lower atmospheric density at the Martian
surface and the likely greater role of direct radiative heating of the
atmosphere within the PBL itself. Most of the modeling techniques used
for the PBL on Earth are also being applied to the Martian PBL,
including novel uses of very high resolution large eddy simulation
methods. We conclude with those aspects of the PBL that require new
measurements in order to constrain models and discuss the extent to
which anticipated missions to Mars in the near future will fulfill these
  doi = {10.1029/2010RG000351},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Spiga}, A.},
  title = {{Elements of comparison between Martian and terrestrial mesoscale meteorological phenomena: Katabatic winds and boundary layer convection}},
  journal = {\planss},
  year = 2011,
  volume = 59,
  pages = {915-922},
  abstract = {{Terrestrial and Martian atmospheres are both characterised by a large
variety of mesoscale meteorological events, occurring at horizontal
scales of hundreds of kilometres and below. Available measurements from
space exploration and recently developed high-resolution numerical tools
have given insights into Martian mesoscale phenomena, as well as
similarities and differences with their terrestrial counterparts. The
remarkable intensity of Martian mesoscale events compared to terrestrial
phenomena mainly results from low density and strong radiative control.
This is exemplified in the present paper by discussing two mesoscale
phenomena encountered in the lowest atmospheric levels of both planets
with notable differences: nighttime katabatic winds (drainage flow down
sloping terrains) and daytime boundary layer convection (vertical growth
of mixed layer over heated surfaces). While observations of katabatic
events are difficult on Earth, except over vast ice sheets, intense
clear-cut downslope circulations are expected to be widespread on Mars.
Convective motions in the daytime Martian boundary layer are primarily
driven by radiative contributions, usually negligible on Earth where
sensible heat flux dominates, and exhibit turbulent variances one order
of magnitude larger. Martian maximum heat fluxes are not attained close
to the surface as on Earth but a few hundreds of metres above, which
implies generalised definitions for mixing layer scales such as vertical
velocity w$_{*}$. Measurements on Mars of winds in uneven
topographical areas and of heat fluxes over flat terrains could be
useful to assess general principles of mesoscale meteorology applicable
to both terrestrial and Martian environments.
  doi = {10.1016/j.pss.2010.04.025},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Selsis}, F. and {Wordsworth}, R.~D. and {Forget}, F.},
  title = {{Thermal phase curves of nontransiting terrestrial exoplanets. I. Characterizing atmospheres}},
  journal = {\aap},
  archiveprefix = {arXiv},
  eprint = {1104.4763},
  primaryclass = {astro-ph.EP},
  keywords = {planets and satellites: atmospheres, planetary systems, standards},
  year = 2011,
  volume = 532,
  eid = {A1},
  pages = {A1},
  abstract = {{Context. Although transit spectroscopy is a very powerful method for
studying the composition, thermal properties, and dynamics of exoplanet
atmospheres, only a few transiting terrestrial exoplanets will be close
enough to allow significant transit spectroscopy with the current and
forthcoming generations of instruments. Thermal phase curves (variations
in the apparent infrared emission of the planet with its orbital phase)
have been observed for hot Jupiters in both transiting and nontransiting
configurations, and have been used to put constraints on the temperature
distribution and atmospheric circulation. This method could be applied
to hot terrestrial exoplanets. 
Aims: We study the wavelength and phase changes of the thermal emission of a tidally-locked terrestrial planet as atmospheric pressure increases. We address the observability of these multiband phase curves and the ability to use them to detect atmospheric constituents.
Methods: We used a 3D climate model (GCM) to simulate the CO$_{2}$ atmosphere of a terrestrial planet on an 8-day orbit around an M 3 dwarf and its apparent infrared emission as a function of its orbital phase. We estimated the signal to photon-noise ratio in narrow bands between 2.5 and 20 {$\mu$}m for a 10 pc target observed with a 6 m and a 1.5 m telescope (respectively the sizes of JWST and EChO).
Results: Atmospheric absorption bands produce associated signatures in what we call the variation spectrum. Atmospheric windows probing the near surface atmospheric layers are needed to produce large, observable phase-curve amplitudes. The number and transparency of these windows, hence the observability of the phase curves and the molecular signatures, decreases with increasing pressure. Planets with no atmosphere produce large variations and can be easily distinguished from dense absorbing atmospheres.
Conclusions: Photon-noise limited spectro-photometry of nearby systems could allow us to detect and characterize the atmosphere of nontransiting terrestrial planets known from radial velocity surveys. Two obvious impediments to these types of observations are the required photometric sensitivity (10$^{-5}$) over the duration of at least one orbit (8-days in the studied case) and the intrinsic stellar variability. However, overcoming these obstacles would give access to one order of magnitude more targets than does transit spectroscopy. }}, doi = {10.1051/0004-6361/201116654}, adsurl = {}, adsnote = {Provided by the SAO/NASA Astrophysics Data System} }
  author = {{Butz}, A. and {Guerlet}, S. and {Hasekamp}, O. and {Schepers}, D. and 
	{Galli}, A. and {Aben}, I. and {Frankenberg}, C. and {Hartmann}, J.-M. and 
	{Tran}, H. and {Kuze}, A. and {Keppel-Aleks}, G. and {Toon}, G. and 
	{Wunch}, D. and {Wennberg}, P. and {Deutscher}, N. and {Griffith}, D. and 
	{Macatangay}, R. and {Messerschmidt}, J. and {Notholt}, J. and 
	{Warneke}, T.},
  title = {{Toward accurate CO$_{2}$ and CH$_{4}$ observations from GOSAT}},
  journal = {\grl},
  keywords = {Atmospheric Composition and Structure: Biosphere/atmosphere interactions (0426, 1610), Atmospheric Composition and Structure: Constituent sources and sinks, Atmospheric Composition and Structure: Radiation: transmission and scattering, Atmospheric Composition and Structure: Troposphere: composition and chemistry, Global Change: Remote sensing (1855, 4337)},
  year = 2011,
  volume = 38,
  eid = {L14812},
  pages = {L14812},
  abstract = {{The column-average dry air mole fractions of atmospheric carbon dioxide
and methane (X$_{CO2}$ and X$_{CH4}$)
are inferred from observations of backscattered sunlight conducted by
the Greenhouse gases Observing SATellite (GOSAT). Comparing the first
year of GOSAT retrievals over land with colocated ground-based
observations of the Total Carbon Column Observing Network (TCCON), we
find an average difference (bias) of -0.05\% and -0.30\% for
X$_{CO2}$ and X$_{CH4}$ with a
station-to-station variability (standard deviation of the bias) of 0.37\%
and 0.26\% among the 6 considered TCCON sites. The root-mean square
deviation of the bias-corrected satellite retrievals from colocated
TCCON observations amounts to 2.8 ppm for X$_{CO2}$ and
0.015 ppm for X$_{CH4}$. Without any data averaging,
the GOSAT records reproduce general source/sink patterns such as the
seasonal cycle of X$_{CO2}$ suggesting the use of the
satellite retrievals for constraining surface fluxes.
  doi = {10.1029/2011GL047888},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Cottereau}, L. and {Rambaux}, N. and {Lebonnois}, S. and {Souchay}, J.
  title = {{The various contributions in Venus rotation rate and LOD}},
  journal = {\aap},
  archiveprefix = {arXiv},
  eprint = {1104.4009},
  primaryclass = {astro-ph.EP},
  keywords = {celestial mechanics, planets and satellites: individual: Venus},
  year = 2011,
  volume = 531,
  eid = {A45},
  pages = {A45},
  abstract = {{Context. Thanks to the Venus Express Mission, new data on the properties
of Venus could be obtained, in particular concerning its rotation. 
Aims: In view of these upcoming results, the purpose of this paper is to determine and compare the major physical processes influencing the rotation of Venus and, more particularly, the angular rotation rate.
Methods: Applying models already used for Earth, the effect of the triaxiality of a rigid Venus on its period of rotation are computed. Then the variations of Venus rotation caused by the elasticity, the atmosphere, and the core of the planet are evaluated.
Results: Although the largest irregularities in the rotation rate of the Earth on short time scales are caused by its atmosphere and elastic deformations, we show that the irregularities for Venus are dominated by the tidal torque exerted by the Sun on its solid body. Indeed, as Venus has a slow rotation, these effects have a large amplitude of two minutes of time (mn). These variations in the rotation rate are greater than the one induced by atmospheric wind variations that can reach 25-50 s of time (s), depending on the simulation used. The variations due to the core effects that vary with its size between 3 and 20 s are smaller. Compared to these effects, the influence of the elastic deformation caused by the zonal tidal potential is negligible.
Conclusions: As the variations in the rotation of Venus reported here are close to 3 mn peak to peak, they should influence past, present, and future observations, thereby providing further constraints on the planet's internal structure and atmosphere. }}, doi = {10.1051/0004-6361/201116606}, adsurl = {}, adsnote = {Provided by the SAO/NASA Astrophysics Data System} }
  author = {{Toyota}, T. and {Kurita}, K. and {Spiga}, A.},
  title = {{Distribution and time-variation of spire streaks at Pavonis Mons on Mars}},
  journal = {\planss},
  year = 2011,
  volume = 59,
  pages = {672-682},
  abstract = {{We documented the distribution and the time-variation of the specific
dark wind streaks at Pavonis Mons. We focused on the streaks we named
{\ldquo}Spire Streaks{\rdquo}, which are overlapping spindle shaped dark
streaks at the upper boundary of the coalesced dark streaks on Tharsis
volcanoes. We investigated both visible and infrared images obtained by
Viking orbiter camera, Mars Orbiter Camera (MOC), THEMIS, CTX and HiRISE
of the spire streaks at Pavonis Mons. We also used topographic data
obtained by Mars Orbiter Laser Altimeter (MOLA) to see the relationship
between the topography and the distribution of the spire streaks. The
spire streaks at Pavonis Mons provide us high-resolution information
about the direction of the nighttime slope wind, and could be indirect
clues for the time-variation of the nighttime environment. We conclude
that the spire streaks are erosional features. However, some features of
the spire streaks reported in this paper are outside the scope of
previous modeling for erosional process, and we need a new category of
model for the formation.
  doi = {10.1016/j.pss.2011.01.015},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Maltagliati}, L. and {Titov}, D.~V. and {Encrenaz}, T. and 
	{Melchiorri}, R. and {Forget}, F. and {Keller}, H.~U. and {Bibring}, J.-P.
  title = {{Annual survey of water vapor behavior from the OMEGA mapping spectrometer onboard Mars Express}},
  journal = {\icarus},
  year = 2011,
  volume = 213,
  pages = {480-495},
  abstract = {{We present here the annual behavior of atmospheric water vapor on Mars,
as observed by the OMEGA spectrometer on board Mars Express during its
first martian year. We consider all the different features of the cycle
of water vapor: temporal evolution, both at a seasonal and at a diurnal
scale; longitudinal distribution; and the vertical profile, through the
variations in the saturation height. We put our results into the context
of the current knowledge on the water cycle through a systematic
comparison with the already published datasets. The seasonal behavior is
in very good agreement with past and simultaneous retrievals both
qualitatively and quantitatively, within the uncertainties. The average
water vapor abundance during the year is {\tilde}10 pr. {$\mu$}m, with an
imbalance between northern and southern hemisphere, in favor of the
first. The maximum of activity, up to 60 pr. {$\mu$}m, occurs at high
northern latitudes during local summer and shows the dominance of the
northern polar cap within the driving processes of the water cycle. A
corresponding maximum at southern polar latitudes during the local
summer is present, but less structured and intense. It reaches {\tilde}25
pr. {$\mu$}m at its peak. Global circulation has some influence in shaping
the water cycle, but it is less prominent than the results from previous
instruments suggest. No significant correlation between water vapor
column density and local hour is detected. We can constrain the amount
of water vapor exchanged between the surface and the atmosphere to few
pr. {$\mu$}m. This is consistent with recent results by OMEGA and PFS-LW.
The action of the regolith layer on the global water cycle seems to be
minor, but it cannot be precisely constrained. The distribution of water
vapor on the planet, after removing the topography, shows the already
known two-maxima system, over Tharsis and Arabia Terra. However, the
Arabia Terra increase is quite fragmented compared with previous
observations. A deep zone of minimum separates the two regions. The
saturation height of water vapor is mainly governed by the variations of
insolation during the year. It is confined within 5-15 km from the
surface at aphelion, while in the perihelion season it stretches up to
55 km of altitude.
  doi = {10.1016/j.icarus.2011.03.030},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Wordsworth}, R.~D. and {Forget}, F. and {Selsis}, F. and {Millour}, E. and 
	{Charnay}, B. and {Madeleine}, J.-B.},
  title = {{Gliese 581d is the First Discovered Terrestrial-mass Exoplanet in the Habitable Zone}},
  journal = {\apjl},
  archiveprefix = {arXiv},
  eprint = {1105.1031},
  primaryclass = {astro-ph.EP},
  keywords = {astrobiology, planets and satellites: atmospheres, planet-star interactions, techniques: spectroscopic},
  year = 2011,
  volume = 733,
  eid = {L48},
  pages = {L48},
  abstract = {{It has been suggested that the recently discovered exoplanet GJ581d
might be able to support liquid water due to its relatively low mass and
orbital distance. However, GJ581d receives 35\% less stellar energy than
Mars and is probably locked in tidal resonance, with extremely low
insolation at the poles and possibly a permanent night side. Under such
conditions, it is unknown whether any habitable climate on the planet
would be able to withstand global glaciation and/or atmospheric
collapse. Here we present three-dimensional climate simulations which
demonstrate that GJ581d will have a stable atmosphere and surface liquid
water for a wide range of plausible cases, making it the first confirmed
super-Earth (exoplanet of 2-10 Earth masses) in the habitable zone. We
find that atmospheres with over 10 bar CO$_{2}$ and varying
amounts of background gas (e.g., N$_{2}$) yield global mean
temperatures above 0{\deg}C for both land and ocean-covered surfaces.
Based on the emitted IR radiation calculated by the model, we propose
observational tests that will allow these cases to be distinguished from
other possible scenarios in the future.
  doi = {10.1088/2041-8205/733/2/L48},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Encrenaz}, T. and {Greathouse}, T.~K. and {Richter}, M.~J. and 
	{Lacy}, J.~H. and {Fouchet}, T. and {Bézard}, B. and {Lefèvre}, F. and 
	{Forget}, F. and {Atreya}, S.~K.},
  title = {{A stringent upper limit to SO$_{2}$ in the Martian atmosphere}},
  journal = {\aap},
  keywords = {planets and satellites: atmospheres, infrared: planetary systems, planets and satellites: individual: Mars},
  year = 2011,
  volume = 530,
  eid = {A37},
  pages = {A37},
  abstract = {{Surfur-bearing molecules have been found at the surface of Mars by the
Viking lander, the Spirit and Opportunity rovers, and the OMEGA infrared
spectrometer aboard Mars Express. However, no gaseous sulfur-bearing
species have ever been detected in the Martian atmosphere. We search for
SO$_{2}$ signatures in the thermal spectrum of Mars at 7.4 {$\mu$}m
using the Texas Echelon Cross Echelle Spectrograph (TEXES) at the NASA
Infrared Telescope Facility (IRTF). Data were obtained on Oct. 12, 2009
(Ls = 353{\deg}), in the 1350-1360 cm$^{-1}$ range, with a spatial
resolution of 1 arcsec (after convolution over three pixels along the
N-S axis and two steps along the E-W axis) and a resolving power of 80
000. To improve the signal-to-noise ratio (S/N), we co-added the Martian
spectrum around the positions of nine selected SO$_{2}$
transitions with a high S/N and no telluric contamination. From a mean
spectrum, averaged over 35 pixels in the region of maximum continuum, we
infer a 2{$\sigma$} upper limit of 0.3 ppb to the SO$_{2}$ mixing
ratio, assuming that our instrumental errors are combined according to
Gaussian statistics. Our upper limit is three times lower than the upper
limit derived by Krasnopolsky (2005, Icarus, 178, 487), who used the
same technique on previous TEXES data. In addition, we derive an upper
limit of 2 ppb at each spatial pixel of the region observed by TEXES,
which covers the longitude ranges 50 E-170 E for latitudes above 30 N,
100 E-170 E for latitudes between 0 and 30 N, and 110 E-170 E for
latitudes between 15 S and 0. The non-detection of localized
SO$_{2}$ sources in the observed area is consistent with a
homogeneous distribution being expected around equinox for
non-condensible species with a lifetime longer than the global mixing
time. In view of the typically large SO$_{2}$/CH$_{4}$ ratio
observed in terrestrial volcanoes, and assuming a comparable volcanic
composition for Mars and the Earth, our result reaffirms that a volcanic
origin is unlikely for any methane in the Martian atmosphere.
  doi = {10.1051/0004-6361/201116820},
  adsurl = {},
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  author = {{Appéré}, T. and {Schmitt}, B. and {Langevin}, Y. and 
	{Douté}, S. and {Pommerol}, A. and {Forget}, F. and {Spiga}, A. and 
	{Gondet}, B. and {Bibring}, J.-P.},
  title = {{Winter and spring evolution of northern seasonal deposits on Mars from OMEGA on Mars Express}},
  journal = {Journal of Geophysical Research (Planets)},
  keywords = {Planetary Sciences: Solid Surface Planets: Ices, Planetary Sciences: Solar System Objects: Mars, Planetary Sciences: Solid Surface Planets: Polar regions, Planetary Sciences: Solid Surface Planets: Remote sensing},
  year = 2011,
  volume = 116,
  eid = {E05001},
  pages = {E05001},
  abstract = {{The OMEGA visible/near-infrared imaging spectrometer on Mars Express has
observed the retreat of the northern seasonal deposits during Martian
year 27-28 from the period of maximum extension, close to the northern
winter solstice, to the end of the retreat at L$_{s}$ 95{\deg}. We
present the temporal and spatial distributions of both CO$_{2}$
and H$_{2}$O ices and propose a scenario that describes the winter
and spring evolution of the northern seasonal deposits. During winter,
the CO$_{2}$-rich condensates are initially transparent and could
be in slab form. A water ice annulus surrounds the sublimating
CO$_{2}$ ice, extending over 6{\deg} of latitude at L$_{s}$
320{\deg}, decreasing to 2{\deg} at L$_{s}$ 350{\deg}, and gradually
increasing to 4.5{\deg} at L$_{s}$ 50{\deg}. This annulus first
consists of thin frost as observed by the Viking Lander 2 and is then
overlaid by H$_{2}$O grains trapped in the CO$_{2}$-rich ice
layer and released during CO$_{2}$ sublimation. By L$_{s}$
50{\deg}, H$_{2}$O ice spectrally dominates most of the deposits.
In order to hide the still several tens of centimeters thick
CO$_{2}$ ice layer in central areas of the cap we propose the
buildup of an optically thick top layer of H$_{2}$O ice from ice
grains previously embedded in the CO$_{2}$ ice and by cold
trapping of water vapor from the sublimating water ice annulus. The
CO$_{2}$ ice signature locally reappears between L$_{s}$
50{\deg} and 70{\deg}. What emerges from our observations is a very active
surface-atmosphere water cycle. These data provide additional
constraints to the general circulation models simulating the Martian
  doi = {10.1029/2010JE003762},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Pilorget}, C. and {Forget}, F. and {Millour}, E. and {Vincendon}, M. and 
	{Madeleine}, J.~B.},
  title = {{Dark spots and cold jets in the polar regions of Mars: New clues from a thermal model of surface CO $_{2}$ ice}},
  journal = {\icarus},
  year = 2011,
  volume = 213,
  pages = {131-149},
  abstract = {{Observations of the martian CO $_{2}$ ice cap in late winter and
spring have revealed exotic phenomena. Unusual dark spots, fans and
blotches form as the south-polar seasonal CO $_{2}$ ice cap
retreats. The formation mechanisms of these features are not clearly
understood. Theoretical models suggest that photons could penetrate deep
into the CO $_{2}$ ice down to the regolith, leading to basal
sublimation and gas and dust ejection. We have developed a detailed
thermal model able to simulate the temporal evolution of the regolith-CO
$_{2}$ ice layer-atmosphere column. It takes into account heat
conduction, radiative transfer within the ice and the atmosphere, and
latent heat exchange when there is a phase transition. We found that a
specific algorithm, fully coupling these three components, was needed to
properly predict ice sublimation below the surface. Our model allows us
to determine under what conditions basal sublimation is possible and
thus when and where it can occur on Mars. Our results show that basal
sublimation is possible if we consider large pathlengths and very little
dust content within the ice. Moreover, the model can explain how dark
spots can appear very early after the end of the polar night at high
latitudes. We also evaluate the importance of the different parameters
in our simulations. Contrary to what was suggested by theoretical
models, the role of seasonal thermal waves is found to be limited. Solar
radiation alone can initiate basal sublimation, which therefore only
depends on the CO $_{2}$ ice properties. Three main modes were
identified: one where condensation/sublimation only occurs at the
surface (in the case of small grains and/or high dust content), one
where basal sublimation is possible (large pathlengths and very little
dust content) and an intermediate mode where sublimation within the ice
may occur. We suggest that these different modes could be keys to
understanding many processes that occur at the surface of Mars, like the
anticryptic area behavior or the recent reported activity in gullies.
  doi = {10.1016/j.icarus.2011.01.031},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Guerlet}, S. and {Fouchet}, T. and {Bézard}, B. and {Flasar}, F.~M. and 
	{Simon-Miller}, A.~A.},
  title = {{Evolution of the equatorial oscillation in Saturn's stratosphere between 2005 and 2010 from Cassini/CIRS limb data analysis}},
  journal = {\grl},
  keywords = {Atmospheric Composition and Structure: Planetary atmospheres (5210, 5405, 5704), Planetary Sciences: Fluid Planets: Atmospheres (0343, 1060), Atmospheric Processes: Middle atmosphere dynamics (0341, 0342), Atmospheric Processes: Remote sensing (4337), Planetary Sciences: Solar System Objects: Saturn},
  year = 2011,
  volume = 38,
  eid = {L09201},
  pages = {L09201},
  abstract = {{We present an analysis of thermal infrared spectra acquired in limb
viewing geometry by Cassini/CIRS in February 2010. We retrieve vertical
profiles of Saturn's stratospheric temperature from 20 hPa to
10$^{-2}$ hPa, at 9 latitudes between 20{\deg}N and 20{\deg}S. Using
the gradient thermal wind equation, we derive a map of the zonal wind
field. Both the temperature and the zonal wind vertical profiles exhibit
an oscillation in the equatorial region. These results are compared to
the temperature and zonal wind maps obtained from 2005-2006 CIRS limb
data, when this oscillation was first reported. In both epochs, strong
temperature anomalies at the equator (up to 20K) are consistent with
adiabatic heating (cooling) due to a sinking (rising) motion at a speed
of 0.1-0.2 mm/s. Finally, we show that the altitude of the maximum
eastward wind has moved downwards by 1.3 scale heights in 4.2 years,
hence with a {\lsquo}phase{\rsquo} speed of {\tilde}0.5 mm/s. This rate is
consistent with the estimated period of 14.7 years for the equatorial
oscillation, and requires a local zonal acceleration of 1.1 {\times}
10$^{-6}$ m.s$^{-2}$ at the 2.5 hPa pressure level. This
downward propagation of the oscillation is consistent with it being
driven by absorption of upwardly propagating waves.
  doi = {10.1029/2011GL047192},
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  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Spiga}, A. and {Forget}, F. and {Madeleine}, J.-B. and {Montabone}, L. and 
	{Lewis}, S.~R. and {Millour}, E.},
  title = {{The impact of martian mesoscale winds on surface temperature and on the determination of thermal inertia}},
  journal = {\icarus},
  year = 2011,
  volume = 212,
  pages = {504-519},
  abstract = {{Radiative control of surface temperature is a key characteristic of the
martian environment and its low-density atmosphere. Here we show through
meteorological modeling that surface temperature can be far from
radiative equilibrium over numerous sloping terrains on Mars, where
nighttime mesoscale katabatic winds impact the surface energy budget.
Katabatic circulations induce both adiabatic atmospheric heating and
enhancement of downward sensible heat flux, which then becomes
comparable to radiative flux and acts to warm the ground. Through this
mechanism, surface temperature can increase up to 20 K. One consequence
is that warm signatures of surface temperature over slopes, observed
through infrared spectrometry, cannot be systematically associated with
contrasts of intrinsic soil thermal inertia. Apparent thermal inertia
maps retrieved thus far possibly contain wind-induced structures.
Another consequence is that surface temperature observations close to
sloping terrains could allow the validation of model predictions for
martian katabatic winds, provided contrasts in intrinsic thermal inertia
can be ruled out. The thermal impact of winds is mostly discussed in
this paper in the particular cases of Olympus Mons/Lycus Sulci and Terra
Meridiani but is generally significant over any sloped terrains in low
thermal inertia areas. It is even general enough to apply under daytime
conditions, thereby providing a possible explanation for observed
afternoon surface cooling, and to ice-covered terrains, thereby
providing new insights on how winds could have shaped the present
surface of Mars.
  doi = {10.1016/j.icarus.2011.02.001},
  adsurl = {},
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  author = {{Parish}, H.~F. and {Schubert}, G. and {Covey}, C. and {Walterscheid}, R.~L. and 
	{Grossman}, A. and {Lebonnois}, S.},
  title = {{Decadal variations in a Venus general circulation model}},
  journal = {\icarus},
  year = 2011,
  volume = 212,
  pages = {42-65},
  abstract = {{The Community Atmosphere Model (CAM), a 3-dimensional Earth-based
climate model, has been modified to simulate the dynamics of the Venus
atmosphere. The most current finite volume version of CAM is used with
Earth-related processes removed, parameters appropriate for Venus
introduced, and some basic physics approximations adopted. A simplified
Newtonian cooling approximation has been used for the radiation scheme.
We use a high resolution (1{\deg} by 1{\deg} in latitude and longitude) to
take account of small-scale dynamical processes that might be important
on Venus. A Rayleigh friction approach is used at the lower boundary to
represent surface drag, and a similar approach is implemented in the
uppermost few model levels providing a {\lsquo}sponge layer{\rsquo} to
prevent wave reflection from the upper boundary. The simulations
generate superrotation with wind velocities comparable to those measured
in the Venus atmosphere by probes and around 50-60\% of those measured by
cloud tracking. At cloud heights and above the atmosphere is always
superrotating with mid-latitude zonal jets that wax and wane on an
approximate 10 year cycle. However, below the clouds, the zonal winds
vary periodically on a decadal timescale between superrotation and
subrotation. Both subrotating and superrotating mid-latitude jets are
found in the approximate 40-60 km altitude range. The growth and decay
of the sub-cloud level jets also occur on the decadal timescale. Though
subrotating zonal winds are found below the clouds, the total angular
momentum of the atmosphere is always in the sense of superrotation. The
global relative angular momentum of the atmosphere oscillates with an
amplitude of about 5\% on the approximate 10 year timescale. Symmetric
instability in the near surface equatorial atmosphere might be the
source of the decadal oscillation in the atmospheric state. Analyses of
angular momentum transport show that all the jets are built up by
poleward transport by a meridional circulation while angular momentum is
redistributed to lower latitudes primarily by transient eddies. Possible
changes in the structure of Venus{\rsquo} cloud level mid-latitude jets
measured by Mariner 10, Pioneer Venus, and Venus Express suggest that a
cyclic variation similar to that found in the model might occur in the
real Venus atmosphere, although no subrotating winds below the cloud
level have been observed to date. Venus{\rsquo} atmosphere must be
observed over multi-year timescales and below the clouds if we are to
understand its dynamics.
  doi = {10.1016/j.icarus.2010.11.015},
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  author = {{Meslin}, P.-Y. and {Gough}, R. and {Lefèvre}, F. and {Forget}, F.
  title = {{Little variability of methane on Mars induced by adsorption in the regolith}},
  journal = {\planss},
  year = 2011,
  volume = 59,
  pages = {247-258},
  abstract = {{The mechanisms that can induce short term variations of methane in the
Martian atmosphere, and thus explain the observations currently
available, are yet to be discovered. Seasonal exchange with the
regolith, caused by reversible adsorption, is expected to induce both
spatial and time variabilities without the need for additional sources
and sinks, thus avoiding difficulties raised by other scenarios.
However, a comprehensive view of the role of reversible exchanges with
the subsurface was still lacking. We have investigated the efficiency of
such a process by implementing a coupled subsurface-atmosphere transport
module in a Global Climate Model, taking into account both the
thermodynamics and the kinetics of the adsorption process. It is based
on recent experimental data on the adsorption of methane. We show that
even with an optimistic set of parameters, and although the regolith can
potentially take up a large fraction of the atmospheric reservoir, the
seasonal variability induced by an exchange with the subsurface is very
limited. If a local plume is detected, however, the apparent decay rate
of methane in the atmosphere can be affected by the regolith uptake.
This study could be extended to any trace gas reacting with the
regolith, to help interpret future in situ or orbital measurements.
  doi = {10.1016/j.pss.2010.09.022},
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  author = {{Atreya}, S.~K. and {Witasse}, O. and {Chevrier}, V.~F. and 
	{Forget}, F. and {Mahaffy}, P.~R. and {Buford Price}, P. and 
	{Webster}, C.~R. and {Zurek}, R.~W.},
  title = {{Methane on Mars: Current observations, interpretation, and future plans}},
  journal = {\planss},
  year = 2011,
  volume = 59,
  pages = {133-136},
  doi = {10.1016/j.pss.2010.10.008},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}