@comment{{This file has been generated by bib2bib 1.94}}
@comment{{Command line: /usr/bin/bib2bib --quiet -c 'not journal:"Discussions"' -c year=2010 -c $type="ARTICLE" -oc pub2010.txt -ob pub2010.bib}}
  author = {{Gonz{\'a}lez-Galindo}, F. and {Bougher}, S.~W. and {L{\'o}pez-Valverde}, M.~A. and 
	{Forget}, F. and {Murphy}, J.},
  title = {{Thermal and wind structure of the Martian thermosphere as given by two General Circulation Models}},
  journal = {\planss},
  year = 2010,
  volume = 58,
  pages = {1832-1849},
  abstract = {{We have used two different General Circulation Models to study the
thermal and wind structure of the Martian upper atmosphere (mesosphere
and thermosphere). Both models take into account the effects of waves
propagating from the lower atmosphere, although they use different
methods for this purpose. We present the results of three simulations
that allow us to take into account the seasonal variability of the
Martian atmosphere. Simplified dust scenarios and a common set of input
parameters are used. The temperatures and winds predicted by both models
show an overall good agreement. However, some differences have been
identified, generally of a local nature. The magnitude of these
differences tends to increase with the amount of dust in the lower
atmosphere. The different heating terms of the upper atmosphere
predicted by both models are in good agreement, which suggests that the
differences between the models have their origin in the propagation of
waves from the lower atmosphere. This study has allowed us to confirm
the important role of the redistribution of the energy by the winds in
producing the longitude-latitude structure of the temperatures. Both
models predict also a thermospheric polar warming during the Southern
summer solstice, although its intensity seems to be model-dependent and
connected to lower atmosphere dust loading.
  doi = {10.1016/j.pss.2010.08.013},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Wordsworth}, R. and {Forget}, F. and {Eymet}, V.},
  title = {{Infrared collision-induced and far-line absorption in dense CO $_{2}$ atmospheres}},
  journal = {\icarus},
  year = 2010,
  volume = 210,
  pages = {992-997},
  abstract = {{Collision-induced absorption is of great importance to the overall
radiative budget in dense CO $_{2}$-rich atmospheres, but its
representation in climate models remains uncertain, mainly due to a lack
of accurate experimental and theoretical data. Here we compare several
parameterisations of the effect, including a new one that makes use of
previously unused measurements in the 1200-1800 cm $^{-1}$
spectral range. We find that a widely used parameterisation strongly
overestimates absorption in pure CO $_{2}$ atmospheres compared to
later results, and propose a new approach that we believe is the most
accurate possible given currently available data.
  doi = {10.1016/j.icarus.2010.06.010},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Wordsworth}, R.~D. and {Forget}, F. and {Selsis}, F. and {Madeleine}, J.-B. and 
	{Millour}, E. and {Eymet}, V.},
  title = {{Is Gliese 581d habitable? Some constraints from radiative-convective climate modeling}},
  journal = {\aap},
  archiveprefix = {arXiv},
  eprint = {1005.5098},
  primaryclass = {astro-ph.EP},
  keywords = {planets and satellites: atmospheres, planets and satellites: surfaces, planetary systems, planet-star interactions, convection, radiative transfer},
  year = 2010,
  volume = 522,
  eid = {A22},
  pages = {A22},
  abstract = {{The recently discovered exoplanet Gl 581d is extremely close to the
outer edge of its system's habitable zone, which has led to much
speculation on its possible climate. We have performed a range of
simulations to assess whether, given simple combinations of chemically
stable greenhouse gases, the planet could sustain liquid water on its
surface. For best estimates of the surface gravity, surface albedo and
cloud coverage, we find that less than 10 bars of CO$_{2}$ is
sufficient to maintain a global mean temperature above the melting point
of water. Furthermore, even with the most conservative choices of these
parameters, we calculate temperatures above the water melting point for
CO$_{2}$ partial pressures greater than about 40 bar. However, we
note that as Gl 581d is probably in a tidally resonant orbit, further
simulations in 3D are required to test whether such atmospheric
conditions are stable against the collapse of CO$_{2}$ on the
  doi = {10.1051/0004-6361/201015053},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Spiga}, A. and {Forget}, F. and {Lewis}, S.~R. and {Hinson}, D.~P.
  title = {{Correction to: `Structure and dynamics of the convective boundary layer on Mars as inferred from large-eddy simulations and remote-sensing measurements'}},
  journal = {Quarterly Journal of the Royal Meteorological Society},
  year = 2010,
  volume = 136,
  pages = {2205-2206},
  doi = {10.1002/qj.725},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Vincendon}, M. and {Forget}, F. and {Mustard}, J.},
  title = {{Water ice at low to midlatitudes on Mars}},
  journal = {Journal of Geophysical Research (Planets)},
  archiveprefix = {arXiv},
  eprint = {1103.0225},
  primaryclass = {astro-ph.EP},
  keywords = {Planetary Sciences: Solid Surface Planets: Ices, Planetary Sciences: Solid Surface Planets: Meteorology (3346), Planetary Sciences: Solid Surface Planets: Atmospheres (0343, 1060), Planetary Sciences: Solid Surface Planets: Remote sensing},
  year = 2010,
  volume = 115,
  number = e14,
  eid = {E10001},
  pages = {E10001},
  abstract = {{In this paper, we analyze water ice occurrences at the surface of Mars
using near-infrared observations, and we study their distribution with a
climate model. Latitudes between 45{\deg}S and 50{\deg}N are considered.
Data from the Observatoire pour la Minéralogie, l'Eau, les Glaces
et l'Actitité and the Compact Reconnaissance Imaging Spectrometer
for Mars are used to assess the presence of surface water ice as a
function of location and season. A modeling approach combining the 1-D
and 3-D versions of the General Circulation Model of the Laboratoire de
Météorologie Dynamique de Jussieu is developed and
successfully compared to observations. Ice deposits 2-200 {$\mu$}m thick
are observed during the day on pole facing slopes in local fall, winter,
and early spring. Ice extends down to 13{\deg} latitude in the Southern
Hemisphere but is restricted to latitudes higher than 32{\deg} in the
north. On a given slope, the pattern of ice observations at the surface
is mainly controlled by the global variability of atmospheric water
(precipitation and vapor), with local ground properties playing a lower
role. Only seasonal surface ice is observed: no exposed patches of
perennial ground ice have been detected. Surface seasonal ice is however
sensitive to subsurface properties: the results presented in this study
are consistent with the recent discovery of low-latitude subsurface ice
obtained through the analysis of CO$_{2}$ frost.
  doi = {10.1029/2010JE003584},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Pathare}, A.~V. and {Balme}, M.~R. and {Metzger}, S.~M. and 
	{Spiga}, A. and {Towner}, M.~C. and {Renno}, N.~O. and {Saca}, F.
  title = {{Assessing the power law hypothesis for the size-frequency distribution of terrestrial and martian dust devils}},
  journal = {\icarus},
  year = 2010,
  volume = 209,
  pages = {851-853},
  abstract = {{Competing hypotheses for the diameter dependence of terrestrial and
martian dust devil frequency are assessed using new field observations
from two sites in the southwestern United States. We show that at
diameters less than 12 m, our observed dust devil size-frequency
distributions are better fit by an exponential function than by a power
law formulation, and discuss the implications for larger dust devils on
Earth and Mars.
  doi = {10.1016/j.icarus.2010.06.027},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Guerlet}, S. and {Fouchet}, T. and {Bézard}, B. and {Moses}, J.~I. and 
	{Fletcher}, L.~N. and {Simon-Miller}, A.~A. and {Michael Flasar}, F.
  title = {{Meridional distribution of CH$_{3}$C$_{2}$H and C$_{4}$H$_{2}$ in Saturn{\rsquo}s stratosphere from CIRS/Cassini limb and nadir observations}},
  journal = {\icarus},
  year = 2010,
  volume = 209,
  pages = {682-695},
  abstract = {{Limb and nadir spectra acquired by Cassini/CIRS (Composite InfraRed
Spectrometer) are analyzed in order to derive, for the first time, the
meridional variations of diacetylene (C $_{4}$H $_{2}$) and
methylacetylene (CH $_{3}$C $_{2}$H) mixing ratios in
Saturn's stratosphere, from 5 hPa up to 0.05 hPa and 80{\deg}S to
45{\deg}N. We find that the C $_{4}$H $_{2}$ and CH
$_{3}$C $_{2}$H meridional distributions mimic that of
acetylene (C $_{2}$H $_{2}$), exhibiting small-scale
variations that are not present in photochemical model predictions. The
most striking feature of the meridional distribution of both molecules
is an asymmetry between mid-southern and mid-northern latitudes. The
mid-southern latitudes are found depleted in hydrocarbons relative to
their northern counterparts. In contrast, photochemical models predict
similar abundances at north and south mid-latitudes. We favor a
dynamical explanation for this asymmetry, with upwelling in the south
and downwelling in the north, the latter coinciding with the region
undergoing ring shadowing. The depletion in hydrocarbons at mid-southern
latitudes could also result from chemical reactions with oxygen-bearing
molecules. Poleward of 60{\deg}S, at 0.1 and 0.05 hPa, we find that the
CH $_{3}$C $_{2}$H and C $_{4}$H $_{2}$
abundances increase dramatically. This behavior is in sharp
contradiction with photochemical model predictions, which exhibit a
strong decrease towards the south pole. Several processes could explain
our observations, such as subsidence, a large vertical eddy diffusion
coefficient at high altitudes, auroral chemistry that enhances CH
$_{3}$C $_{2}$H and C $_{4}$H $_{2}$ production,
or shielding from photolysis by aerosols or molecules produced from
auroral chemistry. However, problems remain with all these hypotheses,
including the lack of similar behavior at lower altitudes. Our derived
mean mixing ratios at 0.5 hPa of (2.4 {\plusmn} 0.3) {\times} 10
$^{-10}$ for C $_{4}$H $_{2}$ and of (1.1 {\plusmn}
0.3) {\times} 10 $^{-9}$ for CH $_{3}$C $_{2}$H are
compatible with the analysis of global-average ISO observations
performed by Moses et al. (Moses, J.I., Bézard, B., Lellouch, E.,
Gladstone, G.R., Feuchtgruber, H., Allen, M. [2000a]. Icarus 143,
244-298). Finally, we provide values for the ratios [CH $_{3}$C
$_{2}$H]/[C $_{2}$H $_{2}$] and [C $_{4}$H
$_{2}$]/[C $_{2}$H $_{2}$] that can constrain the
coupled chemistry of these hydrocarbons.
  doi = {10.1016/j.icarus.2010.03.033},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{M{\"a}{\"a}tt{\"a}nen}, A. and {Montmessin}, F. and {Gondet}, B. and 
	{Scholten}, F. and {Hoffmann}, H. and {Gonz{\'a}lez-Galindo}, F. and 
	{Spiga}, A. and {Forget}, F. and {Hauber}, E. and {Neukum}, G. and 
	{Bibring}, J.-P. and {Bertaux}, J.-L.},
  title = {{Mapping the mesospheric CO $_{2}$ clouds on Mars: MEx/OMEGA and MEx/HRSC observations and challenges for atmospheric models}},
  journal = {\icarus},
  year = 2010,
  volume = 209,
  pages = {452-469},
  abstract = {{This study presents the latest results on the mesospheric CO
$_{2}$ clouds in the martian atmosphere based on observations by
OMEGA and HRSC onboard Mars Express. We have mapped the mesospheric CO
$_{2}$ clouds during nearly three martian years of OMEGA data
yielding a cloud dataset of {\tilde}60 occurrences. The global mapping
shows that the equatorial clouds are mainly observed in a distinct
longitudinal corridor, at seasons L$_{s}$ = 0-60{\deg} and again at
and after L$_{s}$ = 90{\deg}. A recent observation shows that the
equatorial CO $_{2}$ cloud season may start as early as at
L$_{s}$ = 330{\deg}. Three cases of mesospheric midlatitude autumn
clouds have been observed. Two cloud shadow observations enabled the
mapping of the cloud optical depth ( {$\tau$} = 0.01-0.6 with median values
of 0.13-0.2 at {$\lambda$} = 1 {$\mu$}m) and the effective radii (mainly 1-3
{$\mu$}m with median values of 2.0-2.3 {$\mu$}m) of the cloud crystals. The
HRSC dataset of 28 high-altitude cloud observations shows that the
observed clouds reside mainly in the altitude range {\tilde}60-85 km and
their east-west speeds range from 15 to 107 m/s. Two clouds at southern
midlatitudes were observed at an altitude range of 53-62 km. The speed
of one of these southern midlatitude clouds was measured, and it
exhibited west-east oriented speeds between 5 and 42 m/s. The seasonal
and geographical distribution as well as the observed altitudes are
mostly in line with previous work. The LMD Mars Global Climate Model
shows that at the cloud altitude range (65-85 km) the temperatures
exhibit significant daily variability (caused by the thermal tides) with
the coldest temperatures towards the end of the afternoon. The GCM
predicts the coldest temperatures of this altitude range and the season
L$_{s}$ = 0-30{\deg} in the longitudinal corridor where most of the
cloud observations have been made. However, the model does not predict
supersaturation, but the GCM-predicted winds are in fair agreement with
the HRSC-measured cloud speeds. The clouds exhibit variable
morphologies, but mainly cirrus-type, filamented clouds are observed
(nearly all HRSC observations and most of OMEGA observations). In
{\tilde}15\% of OMEGA observations, clumpy, round cloud structures are
observed, but very few clouds in the HRSC dataset show similar
morphology. These observations of clumpy, cumuliform-type clouds raise
questions on the possibility of mesospheric convection on Mars, and we
discuss this hypothesis based on Convective Available Potential Energy
  doi = {10.1016/j.icarus.2010.05.017},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Cordier}, D. and {Mousis}, O. and {Lunine}, J.~I. and {Lebonnois}, S. and 
	{Lavvas}, P. and {Lobo}, L.~Q. and {Ferreira}, A.~G.~M.},
  title = {{About the Possible Role of Hydrocarbon Lakes in the Origin of Titan's Noble Gas Atmospheric Depletion}},
  journal = {\apjl},
  archiveprefix = {arXiv},
  eprint = {1008.3712},
  primaryclass = {astro-ph.EP},
  keywords = {planets and satellites: atmospheres, planets and satellites: individual: Titan, planets and satellites: general},
  year = 2010,
  volume = 721,
  pages = {L117-L120},
  abstract = {{An unexpected feature of Titan's atmosphere is the strong depletion in
primordial noble gases revealed by the Gas Chromatograph Mass
Spectrometer aboard the Huygens probe during its descent on 2005 January
14. Although several plausible explanations have already been
formulated, no definitive response to this issue has yet been found.
Here, we investigate the possible sequestration of these noble gases in
the liquid contained in lakes and wet terrains on Titan and the
consequences for their atmospheric abundances. Considering the
atmosphere and the liquid existing on the soil as a whole system, we
compute the abundance of each noble gas relative to nitrogen. To do so,
we make the assumption of thermodynamic equilibrium between the liquid
and the atmosphere, the abundances of the different constituents being
determined via regular solution theory. We find that xenon's atmospheric
depletion can be explained by its dissolution at ambient temperature in
the liquid presumably present on Titan's soil. In the cases of argon and
krypton, we find that the fractions incorporated in the liquid are
negligible, implying that an alternative mechanism must be invoked to
explain their atmospheric depletion.
  doi = {10.1088/2041-8205/721/2/L117},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Grassi}, D. and {Migliorini}, A. and {Montabone}, L. and {Lebonnois}, S. and 
	{Cardes{\`i}n-Moinelo}, A. and {Piccioni}, G. and {Drossart}, P. and 
	{Zasova}, L.~V.},
  title = {{Thermal structure of Venusian nighttime mesosphere as observed by VIRTIS-Venus Express}},
  journal = {Journal of Geophysical Research (Planets)},
  keywords = {Atmospheric Composition and Structure: Planetary atmospheres (5210, 5405, 5704), Planetary Sciences: Solid Surface Planets: Atmospheres (0343, 1060), Planetary Sciences: Solid Surface Planets: Remote sensing, Planetary Sciences: Solar System Objects: Venus},
  year = 2010,
  volume = 115,
  eid = {E09007},
  pages = {E09007},
  abstract = {{The mapping IR channel of the Visual and Infrared Thermal Imaging
Spectrometer (VIRTIS-M) on board the Venus Express spacecraft observes
the CO$_{2}$ band at 4.3 {$\mu$}m at a spectral resolution adequate
to retrieve the atmospheric temperature profiles in the 65-96 km
altitude range. Observations acquired in the period June 2006 to July
2008 were used to derive average temperature fields as a function of
latitude, subsolar longitude (i.e., local time, LT), and pressure.
Coverage presented here is limited to the nighttime because of the
adverse effects of daytime non-LTE emission on the retrieval procedure
and to southernmost latitudes because of the orientation of the
Venus-Express orbit. Maps of air temperature variability are also
presented as the standard deviation of the population included in each
averaging bin. At the 100 mbar level (about 65 km above the reference
surface), temperatures tend to decrease from the evening to the morning
side despite a local maximum observed around 20-21LT. The cold collar is
evident around 65S, with a minimum temperature at 3LT. Moving to higher
altitudes, local time trends become less evident at 12.6 mbar (about 75
km) where the temperature monotonically increases from middle latitudes
to the southern pole. Nonetheless, at this pressure level, two weaker
local time temperature minima are observed at 23LT and 2LT equatorward
of 60S. Local time trends in temperature reverse about 85 km, where the
morning side is the warmer. The variability at the 100 mbar level is
maximum around 80S and stronger toward the morning side. Moving to
higher altitudes, the morning side always shows the stronger
variability. Southward of 60S, standard deviation presents minimum
values around 12.6 mbar for all the local times.
  doi = {10.1029/2009JE003553},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Encrenaz}, T. and {Greathouse}, T.~K. and {Bézard}, B. and 
	{Fouchet}, T. and {Lefèvre}, F. and {Montmessin}, F. and 
	{Bitner}, M. and {Kruger}, A. and {Richter}, M.~J. and {Lacy}, J.~H. and 
	{Forget}, F. and {Atreya}, S.~K.},
  title = {{Water vapor map of Mars near summer solstice using ground-based infrared spectroscopy}},
  journal = {\aap},
  keywords = {planets and satellites: atmospheres, techniques: spectroscopic, planets and satellites: individual: Mars, planets and satellites: surfaces},
  year = 2010,
  volume = 520,
  eid = {A33},
  pages = {A33},
  abstract = {{Ground-based spatial mapping of Mars provides a unique way to retrieve
the global distribution of minor atmospheric species and to study
transient phenomena or possible variations with the local hour. We have
obtained an instantaneous map of water vapor on Mars near summer
solstice (Ls = 80{\deg}) using the Texas Echelon Cross Echelle
Spectrograph (TEXES) at the NASA Infrared Telescope Facility (IRTF) at
Mauna Kea Observatory. Data have been obtained in the 1230-1245
cm$^{-1}$ range ({$\lambda$} = 8.1 {$\mu$}m), with a spatial resolution
of 1.1 arcsec (after convolution) and a spectral resolution of 0.012
cm$^{-1}$ (R = 10$^{5}$). The map has been retrieved from
the line depth of a weak HDO transition, compared with the line depth of
a weak CO$_{2}$ nearby transition. The TEXES map exhibits a strong
maximum around the northern pole, as expected from previous observations
and from climate model predictions. More interestingly, it shows
longitudinal variations, both at high northern latitudes and at
mid-latitudes, in close agreement with the predictions of the Global
Climate Model developed at the Laboratoire de Meteorologie Dynamique
(LMD GCM). The inferred water vapor mixing ratio is also in good
agreement with the model predictions. The longitudinal variations at mid
latitudes show a general enhancement toward the east. They do not seem
to be due to the effect of local hour, but can be explained by dynamical
effects generated by the topography. The map of surface temperatures,
inferred from the continuum flux, is surprisingly different from the map
expected from the climate models; the source of this discrepancy is
still unclear.
  doi = {10.1051/0004-6361/200913905},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Schmidt}, F. and {Schmitt}, B. and {Douté}, S. and {Forget}, F. and 
	{Jian}, J.-J. and {Martin}, P. and {Langevin}, Y. and {Bibring}, J.-P. and 
	{OMEGA Team}},
  title = {{Sublimation of the Martian CO $_{2}$ Seasonal South Polar Cap}},
  journal = {\planss},
  archiveprefix = {arXiv},
  eprint = {1003.4453},
  primaryclass = {astro-ph.EP},
  year = 2010,
  volume = 58,
  pages = {1129-1138},
  abstract = {{The polar condensation/sublimation of CO $_{2}$, that involve
about one fourth of the atmosphere mass, is the major Martian climatic
cycle. Early observations in visible and thermal infrared have shown
that the sublimation of the Seasonal South Polar Cap (SSPC) is not
symmetric around the geographic South Pole. Here we use observations by
OMEGA/Mars Express in the near-infrared to detect unambiguously the
presence of CO $_{2}$ at the surface, and to estimate albedo.
Second, we estimate the sublimation of CO $_{2}$ released in the
atmosphere and show that there is a two-step process. From Ls=180{\deg}
to 220{\deg}, the sublimation is nearly symmetric with a slight advantage
for the cryptic region. After Ls=220{\deg} the anti-cryptic region
sublimation is stronger. Those two phases are not balanced such that
there is 22\% {\plusmn} 9 more mass the anti-cryptic region, arguing for
more snow precipitation. We compare those results with the MOLA height
measurements. Finally we discuss implications for the Martian atmosphere
about general circulation and gas tracers, e.g. Ar.
  doi = {10.1016/j.pss.2010.03.018},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Morgan}, G.~A. and {Head}, J.~W. and {Forget}, F. and {Madeleine}, J.-B. and 
	{Spiga}, A.},
  title = {{Gully formation on Mars: Two recent phases of formation suggested by links between morphology, slope orientation and insolation history}},
  journal = {\icarus},
  year = 2010,
  volume = 208,
  pages = {658-666},
  abstract = {{The unusual 80 km diameter Noachian-aged Asimov crater in Noachis Terra
(46{\deg}S, 5{\deg}E) is characterized by extensive Noachian-Hesperian
crater fill and a younger superposed annulus of valleys encircling the
margins of the crater floor. These valleys provide an opportunity to
study the relationships of gully geomorphology as a function of changing
slope orientation relative to solar insolation. We found that the level
of development of gullies was highly correlated with slope orientation
and solar insolation. The largest and most complex gully systems, with
the most well-developed fluvial landforms, are restricted to pole-facing
slopes. In contrast, gullies on equator-facing slopes are smaller, more
poorly developed and integrated, more highly degraded, and contain more
impact craters. We used a 1D version of the Laboratoire de
Météorologie Dynamique GCM, and slope geometries
(orientation and angle), driven by predicted spin-axis/orbital parameter
history, to assess the distribution and history of surface temperatures
in these valleys during recent geological history. Surface temperatures
on pole-facing slopes preferential for water ice accumulation and
subsequent melting are predicted to occur as recently as 0.5-2.1 Ma,
which is consistent with age estimates of gully activity elsewhere on
Mars. In contrast, the 1D model predicts that water ice cannot
accumulate on equator-facing slopes until obliquities exceed 45{\deg},
suggesting they are unlikely to have been active over the last 5 Ma. The
correlation of the temperature predictions and the geological evidence
for age differences suggests that there were two phases of gully
formation in the last few million years: an older phase in which
top-down melting occurred on equator-facing slopes and a younger more
robust phase on pole-facing slopes. The similarities of small-scale
fluvial erosion features seen in the gullies on Mars and those observed
in gullies cut by seasonal and perennial snowmelt in the Antarctic Dry
Valleys supports a top-down melting origin for these gullies on Mars.
  doi = {10.1016/j.icarus.2010.02.019},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Lillis}, R.~J. and {Bougher}, S.~W. and {Gonz{\'a}lez-Galindo}, F. and 
	{Forget}, F. and {Smith}, M.~D. and {Chamberlin}, P.~C.},
  title = {{Four Martian years of nightside upper thermospheric mass densities derived from electron reflectometry: Method extension and comparison with GCM simulations}},
  journal = {Journal of Geophysical Research (Planets)},
  keywords = {Planetary Sciences: Solid Surface Planets: Atmospheres (0343, 1060), Planetary Sciences: Solar System Objects: Mars, Atmospheric Composition and Structure: Planetary atmospheres (5210, 5405, 5704), Atmospheric Composition and Structure: Thermosphere: energy deposition (3369), Atmospheric Composition and Structure: Exosphere},
  year = 2010,
  volume = 115,
  eid = {E07014},
  pages = {E07014},
  abstract = {{The long-term dynamics of the Martian upper thermosphere near the
exobase ({\tilde}160-200 km) are still relatively poorly constrained by
data. Electron reflectometry (ER) provides a way to derive, from
electron loss cones, neutral mass densities at these altitudes in the
night hemisphere. Because the Mars Global Surveyor Electron
Reflectometer was not designed for this purpose, uncertainties in
individual measurements are large and thus upper thermospheric
variability can be characterized only on time scales of weeks or longer.
Density measurements are presented at 2 A.M. local time and 185 km
altitude, from April 1999 until November 2006, spanning {\tilde}4 Martian
years. We observe a weaker correlation with lower atmospheric dust
activity than is seen in the lower thermosphere and a weaker correlation
with solar EUV flux than is observed in the dayside exosphere.
Seasonally repeating features are (1) overall expansion/contraction of
the nighttime thermosphere with heliocentric distance, (2) much lower
densities at the aphelion winter pole compared to the perihelion winter
pole, and (3) a short-lived local density maximum at aphelion in the
southern hemisphere. Interannual differences are also observed; in
particular, the interval of low densities in the southern winter occurs
progressively later as solar EUV flux decreases from solar maximum to
solar minimum. Results are compared with predictions from the Mars
Thermosphere General Circulation Model and LMD Mars Global Circulation
atmospheric model frameworks for Ls = 90{\deg}-180{\deg}, which generally
underestimate and overestimate neutral densities, respectively. This
disagreement reflects the difficulty in simulating nightside dynamical
and cooling processes.
  doi = {10.1029/2009JE003529},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Fletcher}, L.~N. and {Achterberg}, R.~K. and {Greathouse}, T.~K. and 
	{Orton}, G.~S. and {Conrath}, B.~J. and {Simon-Miller}, A.~A. and 
	{Teanby}, N. and {Guerlet}, S. and {Irwin}, P.~G.~J. and {Flasar}, F.~M.
  title = {{Seasonal change on Saturn from Cassini/CIRS observations, 2004-2009}},
  journal = {\icarus},
  year = 2010,
  volume = 208,
  pages = {337-352},
  abstract = {{Five years of thermal infrared spectra from the Cassini Composite
Infrared Spectrometer (CIRS) are analyzed to determine the response of
Saturn's atmosphere to seasonal changes in insolation. Hemispheric
mapping sequences at 15.0 cm $^{-1}$ spectral resolution are used
to retrieve the variation in the zonal mean temperatures in the
stratosphere (0.5-5.0 mbar) and upper troposphere (75-800 mbar) between
October 2004 (shortly after the summer solstice in the southern
hemisphere) and July 2009 (shortly before the autumnal equinox).
Saturn's northern mid-latitudes show signs of dramatic warming in the
stratosphere (by 6-10 K) as they emerge from ring-shadow into springtime
conditions, whereas southern mid-latitudes show evidence for cooling
(4-6 K). The 40-K asymmetry in stratospheric temperatures between
northern and southern hemispheres (at 1 mbar) slowly decreased during
the timespan of the observations. Tropospheric temperatures also show
temporal variations but with a smaller range, consistent with the
increasing radiative time constant of the atmospheric response with
increasing pressure. The tropospheric response to the insolation changes
shows the largest magnitude at the locations of the broad retrograde
jets. Saturn's warm south-polar stratospheric hood has cooled over the
course of the mission, but remains present. Stratospheric temperatures
are compared to a radiative climate model which accounts for the spatial
distribution of the stratospheric coolants. The model successfully
predicts the magnitude and morphology of the observed changes at most
latitudes. However, the model fails at locations where strong dynamical
perturbations dominate the temporal changes in the thermal field, such
as the hot polar vortices and the equatorial semi-annual oscillation
(Orton, G., and 27 colleagues [2008]. Nature 453, 196-198). Furthermore,
observed temperatures in Saturn's ring-shadowed regions are larger than
predicted by all radiative-climate models to date due to the incomplete
characterization of the dynamical response to the shadow. Finally,
far-infrared CIRS spectra are used to demonstrate variability of the
para-hydrogen distribution over the 5-year span of the dataset, which
may be related to observed changes in Saturn's tropospheric haze in the
spring hemisphere.
  doi = {10.1016/j.icarus.2010.01.022},
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  author = {{Lebonnois}, S. and {Hourdin}, F. and {Eymet}, V. and {Crespin}, A. and 
	{Fournier}, R. and {Forget}, F.},
  title = {{Superrotation of Venus' atmosphere analyzed with a full general circulation model}},
  journal = {Journal of Geophysical Research (Planets)},
  keywords = {Planetary Sciences: Solid Surface Planets: Meteorology (3346), Atmospheric Processes: Planetary meteorology (5445, 5739), Atmospheric Composition and Structure: Planetary atmospheres (5210, 5405, 5704), Atmospheric Processes: General circulation (1223)},
  year = 2010,
  volume = 115,
  eid = {E06006},
  pages = {E06006},
  abstract = {{A general circulation model (GCM) has been developed for the Venus
atmosphere, from the surface up to 100 km altitude, based on the GCM
developed for Earth at our laboratory. Key features of this new GCM
include topography, diurnal cycle, dependence of the specific heat on
temperature, and a consistent radiative transfer module based on net
exchange rate matrices. This allows a consistent computation of the
temperature field, in contrast to previous GCMs of Venus atmosphere that
used simplified temperature forcing. The circulation is analyzed after
350 Venus days (111 Earth years). Superrotation is obtained above
roughly 40 km altitude. Below, the zonal wind remains very small
compared to observed values, which is a major pending question. The
meridional circulation consists of equator-to-pole cells, the dominant
one being located within the cloud layers. The modeled temperature
structure is globally consistent with observations, though discrepancies
persist in the stability of the lowest layers and equator-pole
temperature contrast within the clouds (10 K in the model compared to
the observed 40 K). In agreement with observational data, a convective
layer is found between the base of the clouds (around 47 km) and the
middle of the clouds (55-60 km altitude). The transport of angular
momentum is analyzed, and comparison between the reference simulation
and a simulation without diurnal cycle illustrates the role played by
thermal tides in the equatorial region. Without diurnal cycle, the
Gierasch-Rossow-Williams mechanism controls angular momentum transport.
The diurnal tides add a significant downward transport of momentum in
the equatorial region, causing low latitude momentum accumulation.
  doi = {10.1029/2009JE003458},
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  author = {{McDunn}, T.~L. and {Bougher}, S.~W. and {Murphy}, J. and {Smith}, M.~D. and 
	{Forget}, F. and {Bertaux}, J.-L. and {Montmessin}, F.},
  title = {{Simulating the density and thermal structure of the middle atmosphere ({\tilde}80-130 km) of Mars using the MGCM-MTGCM: A comparison with MEX/SPICAM observations}},
  journal = {\icarus},
  year = 2010,
  volume = 206,
  pages = {5-17},
  abstract = {{The objective of this work is to advance the understanding of the
structure and dynamics of the middle altitude region of the martian
atmosphere. While numerous advancements have been made in the level of
scientific understanding of Mars's upper and lower atmospheres over the
past several decades, insight into the mechanisms of the middle
atmosphere has come at a significantly slower pace due to the small
number of datasets available for this region. Over the past decade this
has begun to change, with renewed interest by NASA and ESA to send
spacecraft to Mars. The result of these recent efforts is a growing
database for Mars's middle atmosphere, enabling long-awaited and
necessary studies characterizing the middle altitude region. Various
numerical models of the martian atmosphere can now be validated and
constrained using this database. We utilize the Mars
Express/Spectroscopy for the Investigation of the Characteristics of the
Atmosphere of Mars (MEX/SPICAM) density and temperature datasets to
characterize the middle atmosphere as well as validate and constrain the
coupled multi-dimensional Mars General Circulation Model-Mars
Thermosphere General Circulation Model (MGCM-MTGCM) at middle altitudes
in order to explore the underlying physics controlling the structure and
dynamics at these levels. The results of this study stress the
importance of proper dust prescription within the MGCM-MTGCM for
accurately reproducing the density and thermal structure of the middle
and upper atmosphere regions on Mars. Simulations conducted with
horizontal dust opacities that are consistent with the SPICAM
observation period (i.e. Mars Odyssey/THEMIS opacities) yield modeled
densities and temperatures that are closer to the observed values than
simulations conducted with ``typical'' dust conditions (i.e. Mars Global
Surveyor/TES opacities). We show that the MGCM-MTGCM closely reproduces
the observed densities during low-dust and high-dust scenarios but
displays difficulty during the pre-dust-season ``ramp-up'' period ( L
$_{s}$ {\tilde} 120-200{\deg}) during MY27. In addition, we show
that the MGCM-MTGCM accurately reproduces the temperature profiles below
the mesopause, but, the mesopause altitude is too low and its
temperature warmer (5-10 K) than observations. This may be related to
nightside dynamical heating processes that require further refinement.
In addition, CO $_{2}$ 15-{$\mu$}m cooling rates may be too small,
which would be consistent with underestimated atomic O abundances.
  doi = {10.1016/j.icarus.2009.06.034},
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  author = {{Spiga}, A. and {Forget}, F. and {Lewis}, S.~R. and {Hinson}, D.~P.
  title = {{Structure and dynamics of the convective boundary layer on Mars as inferred from large-eddy simulations and remote-sensing measurements}},
  journal = {Quarterly Journal of the Royal Meteorological Society},
  year = 2010,
  volume = 136,
  pages = {414-428},
  abstract = {{The structure of the Martian convective boundary layer (BL) is decribed
by means of a novel approach involving both modelling and data analysis.
Mars Express radio-occultation (RO) temperature profiles are compared to
large-eddy simulations (LESs) performed with the Martian mesoscale
model. The model combines the Martian radiative transfer, soil and
surface layer schemes designed at Laboratoire de
M{\~A}{\copy}t{\~A}{\copy}orologie Dynamique (LMD) with the most
recent version of the Weather Research and Forecast (WRF) fully
compressible non-hydrostatic dynamical core. The key roles of the
vertical resolution and, to lesser extent, of the domain horizontal
extent have been investigated to ensure the robustness of the LES
results. The dramatic regional variations of the BL depth are
quantitatively reproduced by the Martian LES. Intense BL dynamics are
found to underlie the measured depths (up to 9 km): vertical speed up to
20 m s-1, heat flux up to 2.7 K m s-1 and turbulent kinetic energy up to 26 
m2 s-2. Under specific conditions, both the model and the
measurements show a distinctive positive correlation between surface
topography and BL depth. Our interpretation is that, in the tenuous CO2
Martian near-surface environment, the daytime BL is to first order
controlled by the infrared radiative heating, fairly independent of
elevation, which implies a simple correlation between the BL potential
temperature and the inverse pressure (``pressure effect''). No prominent 
``pressure effect'' is in action on Earth where sensible heat flux
dominates the BL energy budget. Both RO observations and numerical
simulations confirm the terrain-following behaviour of near-surface
temperature on Mars induced by the dominant radiative influence. The
contribution of the Martian sensible heat flux is not negligible and
results in a given isotherm in the BL being comparatively closer to the
ground at higher surface elevation. The strong radiative control of the
Martian convective BL implies a generalised formulation for the BL
dimensionless quantities. Based on this formulation and the variety of
simulated BL depths by the LES, new similarity relationships for the
Martian convective BL in quasi-steady midday conditions are derived.
Rigorous comparisons between the Martian and terrestrial BL and fast
computations of the mean Martian BL turbulent statistics are now made
possible by such similarity laws.
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  author = {{Vincendon}, M. and {Mustard}, J. and {Forget}, F. and {Kreslavsky}, M. and 
	{Spiga}, A. and {Murchie}, S. and {Bibring}, J.-P.},
  title = {{Near-tropical subsurface ice on Mars}},
  journal = {\grl},
  archiveprefix = {arXiv},
  eprint = {1103.0379},
  primaryclass = {astro-ph.EP},
  keywords = {Planetary Sciences: Solid Surface Planets: Atmospheres (0343, 1060), Planetary Sciences: Solid Surface Planets: Ices, Planetary Sciences: Solid Surface Planets: Meteorology (3346), Planetary Sciences: Solid Surface Planets: Remote sensing},
  year = 2010,
  volume = 37,
  eid = {L01202},
  pages = {L01202},
  abstract = {{Near-surface perennial water ice on Mars has been previously inferred
down to latitudes of about 45{\deg} and could result from either water
vapor diffusion through the regolith under current conditions or
previous ice ages precipitations. In this paper we show that at
latitudes as low as 25{\deg} in the southern hemisphere buried water ice
in the shallow ($\lt$1 m) subsurface is required to explain the observed
surface distribution of seasonal CO$_{2}$ frost on pole facing
slopes. This result shows that possible remnants of the last ice age, as
well as water that will be needed for the future exploration of Mars,
are accessible significantly closer to the equator than previously
thought, where mild conditions for both robotic and human exploration
  doi = {10.1029/2009GL041426},
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  author = {{Spiga}, A. and {Lewis}, S.~R.},
  title = {{Martian mesoscale and microscale wind variability of relevance for dust lifting}},
  journal = {International Journal of Mars Science and Exploration},
  year = 2010,
  volume = 5,
  pages = {146-158},
  abstract = {{Background: Mars is both a windy and dusty environment. Ariborne dust is
a crucial climate component on Mars. It impacts atmospheric circulations
at large-, meso- and micro-scales, which in turn control dust lifting
from the surface and transport in the atmosphere. Dust lifting processes
and feedbacks on atmospheric circulations are currently not well
understood. Method: Our purpose is to show how mesoscale models and
large-eddy simulations help to explore small-scale circulation patterns
which are potentially important for lifting dust into the atmosphere but
which are unresolved by global climate models. We focus on variations of
friction velocity, u*, relevant for dust lifting, in particular
investigating maximum values and the spatial and temporal variability of
u*. Conclusion: Meteorological scales between 100 km and 10 km can be
studied by high-resolution global circulation and limited-area mesoscale
models, which both show strong topographic control of the daytime and
nighttime near-surface winds. Scales below 10 km and 1 km are dominated
by turbulent gusts and dust devils, two distinct convective boundary
layer processes likely to lift dust from the surface. In low-latitude
regions, boundary layer depth and friction velocity u* are correlated
with surface altimetry. Further studies will be carried out to
parameterize lifting by boundary layer processes and dust radiative
effects once transported in the atmosphere.
  doi = {10.1555/mars.2010.0006},
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