@comment{{This file has been generated by bib2bib 1.94}}
@comment{{Command line: /usr/bin/bib2bib --quiet -c 'not journal:"Discussions"' -c year=2012 -c $type="ARTICLE" -oc pub2012.txt -ob pub2012.bib}}
  author = {{Lebonnois}, S. and {Covey}, C. and {Grossman}, A. and {Parish}, H. and 
	{Schubert}, G. and {Walterscheid}, R. and {Lauritzen}, P. and 
	{Jablonowski}, C.},
  title = {{Angular momentum budget in General Circulation Models of superrotating atmospheres: A critical diagnostic}},
  journal = {Journal of Geophysical Research (Planets)},
  keywords = {Atmospheric Composition and Structure: Planetary atmospheres (5210, 5405, 5704), Atmospheric Processes: General circulation (1223), Planetary Sciences: Solid Surface Planets: Atmospheres (0343, 1060), Planetary Sciences: Solar System Objects: Venus},
  year = 2012,
  volume = 117,
  number = e16,
  eid = {E12004},
  pages = {E12004},
  abstract = {{To help understand the large disparity in the results of circulation
modeling for the atmospheres of Titan and Venus, where the whole
atmosphere rotates faster than the surface (superrotation), the
atmospheric angular momentum budget is detailed for two General
Circulation Models (GCMs). The LMD GCM is tested for both Venus (with
simplified and with more realistic physical forcings) and Titan
(realistic physical forcings). The Community Atmosphere Model is tested
for both Earth and Venus with simplified physical forcings. These
analyses demonstrate that errors related to atmospheric angular momentum
conservation are significant, especially for Venus when the physical
forcings are simplified. Unphysical residuals that have to be balanced
by surface friction and mountain torques therefore affect the overall
circulation. The presence of topography increases exchanges of angular
momentum between surface and atmosphere, reducing the impact of these
numerical errors. The behavior of GCM dynamical cores with regard to
angular momentum conservation under Venus conditions provides an
explanation of why recent GCMs predict dissimilar results despite
identical thermal forcing. The present study illustrates the need for
careful and detailed analysis of the angular momentum budget for any GCM
used to simulate superrotating atmospheres.
  doi = {10.1029/2012JE004223},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Madeleine}, J.-B. and {Forget}, F. and {Millour}, E. and {Navarro}, T. and 
	{Spiga}, A.},
  title = {{The influence of radiatively active water ice clouds on the Martian climate}},
  journal = {\grl},
  keywords = {Atmospheric Composition and Structure: Cloud/radiation interaction, Atmospheric Composition and Structure: Planetary atmospheres (5210, 5405, 5704), Atmospheric Processes: Clouds and cloud feedbacks, Planetary Sciences: Solid Surface Planets: Atmospheres (0343, 1060), Planetary Sciences: Solar System Objects: Mars},
  year = 2012,
  volume = 39,
  eid = {L23202},
  pages = {L23202},
  abstract = {{Radiatively active water ice clouds (RAC) play a key role in shaping the
thermal structure of the Martian atmosphere. In this paper, RAC are
implemented in the LMD Mars Global Climate Model (GCM) and the simulated
temperatures are compared to Thermal Emission Spectrometer observations
over a full year. RAC change the temperature gradients and global
dynamics of the atmosphere and this change in dynamics in turn implies
large-scale adiabatic temperature changes. Therefore, clouds have both a
direct and indirect effect on atmospheric temperatures. RAC successfully
reduce major GCM temperature biases, especially in the regions of
formation of the aphelion cloud belt where a cold bias of more than 10 K
is corrected. Departures from the observations are however seen in the
polar regions, and highlight the need for better modeling of cloud
formation and evolution.
  doi = {10.1029/2012GL053564},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Balme}, M.~R. and {Pathare}, A. and {Metzger}, S.~M. and {Towner}, M.~C. and 
	{Lewis}, S.~R. and {Spiga}, A. and {Fenton}, L.~K. and {Renno}, N.~O. and 
	{Elliott}, H.~M. and {Saca}, F.~A. and {Michaels}, T.~I. and 
	{Russell}, P. and {Verdasca}, J.},
  title = {{Field measurements of horizontal forward motion velocities of terrestrial dust devils: Towards a proxy for ambient winds on Mars and Earth}},
  journal = {\icarus},
  year = 2012,
  volume = 221,
  pages = {632-645},
  abstract = {{Dust devils - convective vortices made visible by the dust and debris
they entrain - are common in arid environments and have been observed on
Earth and Mars. Martian dust devils have been identified both in images
taken at the surface and in remote sensing observations from orbiting
spacecraft. Observations from landing craft and orbiting instruments
have allowed the dust devil translational forward motion (ground
velocity) to be calculated, but it is unclear how these velocities
relate to the local ambient wind conditions, for (i) only model wind
speeds are generally available for Mars, and (ii) on Earth only
anecdotal evidence exists that compares dust devil ground velocity with
ambient wind velocity. If dust devil ground velocity can be reliably
correlated to the ambient wind regime, observations of dust devils could
provide a proxy for wind speed and direction measurements on Mars.
Hence, dust devil ground velocities could be used to probe the
circulation of the martian boundary layer and help constrain climate
models or assess the safety of future landing sites.

We present results from a field study of terrestrial dust devils
performed in the southwest USA in which we measured dust devil
horizontal velocity as a function of ambient wind velocity. We acquired
stereo images of more than a 100 active dust devils and recorded
multiple size and position measurements for each dust devil. We used
these data to calculate dust devil translational velocity. The dust
devils were within a study area bounded by 10 m high meteorology towers
such that dust devil speed and direction could be correlated with the
local ambient wind speed and direction measurements.

Daily (10:00-16:00 local time) and 2-h averaged dust devil ground speeds
correlate well with ambient wind speeds averaged over the same period.
Unsurprisingly, individual measurements of dust devil ground speed match
instantaneous measurements of ambient wind speed more poorly; a 20-min
smoothing window applied to the ambient wind speed data improves the
correlation. In general, dust devils travel 10-20\% faster than ambient
wind speed measured at 10 m height, suggesting that their ground speeds
are representative of the boundary layer winds a few tens of meters
above ground level. Dust devil ground motion direction closely matches
the measured ambient wind direction.

The link between ambient winds and dust devil ground velocity
demonstrated here suggests that a similar one should apply on Mars.
Determining the details of the martian relationship between dust devil
ground velocity and ambient wind velocity might require new in situ or
modelling studies but, if completed successfully, would provide a
quantitative means of measuring wind velocities on Mars that would
otherwise be impossible to obtain.
  doi = {10.1016/j.icarus.2012.08.021},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Spiga}, A.},
  title = {{Comment on ''Observing desert dust devils with a pressure logger`` by Lorenz (2012) - insights on measured pressure fluctuations from large-eddy simulations}},
  journal = {Geoscientific Instrumentation, Methods and Data Systems},
  year = 2012,
  volume = 1,
  pages = {151-154},
  abstract = {{Lorenz et al. (2012) proposes to use pressure loggers for long-term
field measurements in terrestrial deserts. The dataset obtained through
this method features both pressure drops (reminiscent of dust devils)
and periodic convective signatures. Here we use large-eddy simulations
to provide an explanation for those periodic convective signatures and
to argue that pressure measurements in deserts have broader applications
than monitoring dust devils.
  doi = {10.5194/gi-1-151-2012},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Tinetti}, G. and {Beaulieu}, J.~P. and {Henning}, T. and {Meyer}, M. and 
	{Micela}, G. and {Ribas}, I. and {Stam}, D. and {Swain}, M. and 
	{Krause}, O. and {Ollivier}, M. and {Pace}, E. and {Swinyard}, B. and 
	{Aylward}, A. and {van Boekel}, R. and {Coradini}, A. and {Encrenaz}, T. and 
	{Snellen}, I. and {Zapatero-Osorio}, M.~R. and {Bouwman}, J. and 
	{Cho}, J.~Y.-K. and {Coudé de Foresto}, V. and {Guillot}, T. and 
	{Lopez-Morales}, M. and {Mueller-Wodarg}, I. and {Palle}, E. and 
	{Selsis}, F. and {Sozzetti}, A. and {Ade}, P.~A.~R. and {Achilleos}, N. and 
	{Adriani}, A. and {Agnor}, C.~B. and {Afonso}, C. and {Allende Prieto}, C. and 
	{Bakos}, G. and {Barber}, R.~J. and {Barlow}, M. and {Batista}, V. and 
	{Bernath}, P. and {Bézard}, B. and {Bordé}, P. and {Brown}, L.~R. and 
	{Cassan}, A. and {Cavarroc}, C. and {Ciaravella}, A. and {Cockell}, C. and 
	{Coustenis}, A. and {Danielski}, C. and {Decin}, L. and {De Kok}, R. and 
	{Demangeon}, O. and {Deroo}, P. and {Doel}, P. and {Drossart}, P. and 
	{Fletcher}, L.~N. and {Focardi}, M. and {Forget}, F. and {Fossey}, S. and 
	{Fouqué}, P. and {Frith}, J. and {Galand}, M. and {Gaulme}, P. and 
	{Gonz{\'a}lez Hern{\'a}ndez}, J.~I. and {Grasset}, O. and {Grassi}, D. and 
	{Grenfell}, J.~L. and {Griffin}, M.~J. and {Griffith}, C.~A. and 
	{Gr{\"o}zinger}, U. and {Guedel}, M. and {Guio}, P. and {Hainaut}, O. and 
	{Hargreaves}, R. and {Hauschildt}, P.~H. and {Heng}, K. and 
	{Heyrovsky}, D. and {Hueso}, R. and {Irwin}, P. and {Kaltenegger}, L. and 
	{Kervella}, P. and {Kipping}, D. and {Koskinen}, T.~T. and {Kov{\'a}cs}, G. and 
	{La Barbera}, A. and {Lammer}, H. and {Lellouch}, E. and {Leto}, G. and 
	{Lopez Morales}, M. and {Lopez Valverde}, M.~A. and {Lopez-Puertas}, M. and 
	{Lovis}, C. and {Maggio}, A. and {Maillard}, J.~P. and {Maldonado Prado}, J. and 
	{Marquette}, J.~B. and {Martin-Torres}, F.~J. and {Maxted}, P. and 
	{Miller}, S. and {Molinari}, S. and {Montes}, D. and {Moro-Martin}, A. and 
	{Moses}, J.~I. and {Mousis}, O. and {Nguyen Tuong}, N. and {Nelson}, R. and 
	{Orton}, G.~S. and {Pantin}, E. and {Pascale}, E. and {Pezzuto}, S. and 
	{Pinfield}, D. and {Poretti}, E. and {Prinja}, R. and {Prisinzano}, L. and 
	{Rees}, J.~M. and {Reiners}, A. and {Samuel}, B. and {S{\'a}nchez-Lavega}, A. and 
	{Forcada}, J.~S. and {Sasselov}, D. and {Savini}, G. and {Sicardy}, B. and 
	{Smith}, A. and {Stixrude}, L. and {Strazzulla}, G. and {Tennyson}, J. and 
	{Tessenyi}, M. and {Vasisht}, G. and {Vinatier}, S. and {Viti}, S. and 
	{Waldmann}, I. and {White}, G.~J. and {Widemann}, T. and {Wordsworth}, R. and 
	{Yelle}, R. and {Yung}, Y. and {Yurchenko}, S.~N.},
  title = {{EChO. Exoplanet characterisation observatory}},
  journal = {Experimental Astronomy},
  archiveprefix = {arXiv},
  eprint = {1112.2728},
  primaryclass = {astro-ph.EP},
  keywords = {Exoplanets, Planetary atmospheres, Space mission},
  year = 2012,
  volume = 34,
  pages = {311-353},
  abstract = {{A dedicated mission to investigate exoplanetary atmospheres represents a
major milestone in our quest to understand our place in the universe by
placing our Solar System in context and by addressing the suitability of
planets for the presence of life. EChO{\mdash}the Exoplanet
Characterisation Observatory{\mdash}is a mission concept specifically
geared for this purpose. EChO will provide simultaneous,
multi-wavelength spectroscopic observations on a stable platform that
will allow very long exposures. The use of passive cooling, few moving
parts and well established technology gives a low-risk and potentially
long-lived mission. EChO will build on observations by Hubble, Spitzer
and ground-based telescopes, which discovered the first molecules and
atoms in exoplanetary atmospheres. However, EChO's configuration and
specifications are designed to study a number of systems in a consistent
manner that will eliminate the ambiguities affecting prior observations.
EChO will simultaneously observe a broad enough spectral
region{\mdash}from the visible to the mid-infrared{\mdash}to constrain
from one single spectrum the temperature structure of the atmosphere,
the abundances of the major carbon and oxygen bearing species, the
expected photochemically-produced species and magnetospheric signatures.
The spectral range and resolution are tailored to separate bands
belonging to up to 30 molecules and retrieve the composition and
temperature structure of planetary atmospheres. The target list for EChO
includes planets ranging from Jupiter-sized with equilibrium
temperatures T $_{eq}$ up to 2,000 K, to those of a few Earth
masses, with T $_{eq}$ u223c 300 K. The list will include planets
with no Solar System analog, such as the recently discovered planets
GJ1214b, whose density lies between that of terrestrial and gaseous
planets, or the rocky-iron planet 55 Cnc e, with day-side temperature
close to 3,000 K. As the number of detected exoplanets is growing
rapidly each year, and the mass and radius of those detected steadily
decreases, the target list will be constantly adjusted to include the
most interesting systems. We have baselined a dispersive spectrograph
design covering continuously the 0.4-16 {$\mu$}m spectral range in 6
channels (1 in the visible, 5 in the InfraRed), which allows the
spectral resolution to be adapted from several tens to several hundreds,
depending on the target brightness. The instrument will be mounted
behind a 1.5 m class telescope, passively cooled to 50 K, with the
instrument structure and optics passively cooled to u223c45 K. EChO will
be placed in a grand halo orbit around L2. This orbit, in combination
with an optimised thermal shield design, provides a highly stable
thermal environment and a high degree of visibility of the sky to
observe repeatedly several tens of targets over the year. Both the
baseline and alternative designs have been evaluated and no critical
items with Technology Readiness Level (TRL) less than 4-5 have been
identified. We have also undertaken a first-order cost and development
plan analysis and find that EChO is easily compatible with the ESA
M-class mission framework.
  doi = {10.1007/s10686-012-9303-4},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Lorenz}, R.~D. and {Newman}, C.~E. and {Tokano}, T. and {Mitchell}, J.~L. and 
	{Charnay}, B. and {Lebonnois}, S. and {Achterberg}, R.~K.},
  title = {{Formulation of a wind specification for Titan late polar summer exploration}},
  journal = {\planss},
  year = 2012,
  volume = 70,
  pages = {73-83},
  abstract = {{Titan's polar regions, and its hydrocarbon lakes in particular, are of
interest for future exploration. The polar conditions have considerable
seasonal variation and are distinct from the equatorial environment
experienced by Huygens. Thus specific environmental models are required
for these regions. This paper, informed by Cassini and groundbased
observations and four independent Global Circulation Models (GCMs),
summarizes northern summer polar conditions (specifically, regions north
of 65{\deg}N, during the 2023-2024 period, or solar longitude
L$_{s}${\tilde}150$^{o}$-170{\deg}) and presents a simple
analytical formulation of expected, minimum and maximum winds as a
function of altitude to aid spacecraft and instrument design for future
exploration, with particular reference to the descent dispersions of the
Titan Mare Explorer (TiME) mission concept presently under development.
We also consider winds on the surface, noting that these (of relevance
for impact conditions, for waves, and for wind-driven drift of a
floating capsule) are weaker than those in the lowest cell in most GCMs:
some previously-reported estimates of 'surface' wind speeds (actually at
90-500 m altitude) should be reduced by 20-35\% to refer to the standard
10 m 'anemometer height' applicable for surface phenomena. A Weibull
distribution with scale speed C=0.4 m/s and shape parameter k=2.0
embraces the GCM-predicted surface wind speeds.
  doi = {10.1016/j.pss.2012.05.015},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Dehant}, V. and {Banerdt}, B. and {Lognonné}, P. and {Grott}, M. and 
	{Asmar}, S. and {Biele}, J. and {Breuer}, D. and {Forget}, F. and 
	{Jaumann}, R. and {Johnson}, C. and {Knapmeyer}, M. and {Langlais}, B. and 
	{Le Feuvre}, M. and {Mimoun}, D. and {Mocquet}, A. and {Read}, P. and 
	{Rivoldini}, A. and {Romberg}, O. and {Schubert}, G. and {Smrekar}, S. and 
	{Spohn}, T. and {Tortora}, P. and {Ulamec}, S. and {Vennerstr{\o}m}, S.
  title = {{Future Mars geophysical observatories for understanding its internal structure, rotation, and evolution}},
  journal = {\planss},
  year = 2012,
  volume = 68,
  pages = {123-145},
  abstract = {{Our fundamental understanding of the interior of the Earth comes from
seismology, geodesy, geochemistry, geomagnetism, geothermal studies, and
petrology. For the Earth, measurements in those disciplines of
geophysics have revealed the basic internal layering of the Earth, its
dynamical regime, its thermal structure, its gross compositional
stratification, as well as significant lateral variations in these
quantities. Planetary interiors not only record evidence of conditions
of planetary accretion and differentiation, they exert significant
control on surface environments. We present recent advances in possible
in-situ investigations of the interior of Mars, experiments and
strategies that can provide unique and critical information about the
fundamental processes of terrestrial planet formation and evolution.
Such investigations applied on Mars have been ranked as a high priority
in virtually every set of European, US and international high-level
planetary science recommendations for the past 30 years. New
seismological methods and approaches based on the cross-correlation of
seismic noise by two seismic stations/landers on the surface of Mars and
on joint seismic/orbiter detection of meteorite impacts, as well as the
improvement of the performance of Very Broad-Band (VBB) seismometers
have made it possible to secure a rich scientific return with only two
simultaneously recording stations. In parallel, use of interferometric
methods based on two Earth-Mars radio links simultaneously from landers
tracked from Earth has increased the precision of radio science
experiments by one order of magnitude. Magnetometer and heat flow
measurements will complement seismic and geodetic data in order to
obtain the best information on the interior of Mars. In addition to
studying the present structure and dynamics of Mars, these measurements
will provide important constraints for the astrobiology of Mars by
helping to understand why Mars failed to sustain a magnetic field, by
helping to understand the planet's climate evolution, and by providing a
limit for the energy available to the chemoautotrophic biosphere through
a measurement of the surface heat flow. The landers of the mission will
also provide meteorological stations to monitor the climate and obtain
new measurements in the atmospheric boundary layer.
  doi = {10.1016/j.pss.2011.10.016},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Clancy}, R.~T. and {Sandor}, B.~J. and {Wolff}, M.~J. and {Smith}, M.~D. and 
	{Lefèvre}, F. and {Madeleine}, J.-B. and {Forget}, F. and 
	{Murchie}, S.~L. and {Seelos}, F.~P. and {Seelos}, K.~D. and 
	{Nair}, H.~A. and {Toigo}, A.~D. and {Humm}, D. and {Kass}, D.~M. and 
	{Kleinb{\"o}hl}, A. and {Heavens}, N.},
  title = {{Extensive MRO CRISM observations of 1.27 {$\mu$}m O$_{2}$ airglow in Mars polar night and their comparison to MRO MCS temperature profiles and LMD GCM simulations}},
  journal = {Journal of Geophysical Research (Planets)},
  keywords = {Planetary Sciences: Solid Surface Planets: Atmospheres (0343, 1060), Planetary Sciences: Solid Surface Planets: Aurorae and airglow, Planetary Sciences: Solid Surface Planets: Polar regions, Planetary Sciences: Solid Surface Planets: Remote sensing, Planetary Sciences: Solar System Objects: Mars},
  year = 2012,
  volume = 117,
  eid = {E00J10},
  pages = {E00J10},
  abstract = {{The Martian polar night distribution of 1.27 {$\mu$}m (0-0) band
emission from O$_{2}$ singlet delta
[O$_{2}$($^{1}${$\Delta$}$_{g}$)] is determined from an
extensive set of Mars Reconnaissance Orbiter (MRO) Compact
Reconnaissance Imaging Spectral Mapping (CRISM) limb scans observed over
a wide range of Mars seasons, high latitudes, local times, and
longitudes between 2009 and 2011. This polar nightglow reflects
meridional transport and winter polar descent of atomic oxygen produced
from CO$_{2}$ photodissociation. A distinct peak in 1.27 {$\mu$}m
nightglow appears prominently over 70-90NS latitudes at
40-60 km altitudes, as retrieved for over 100 vertical profiles of
O$_{2}$($^{1}${$\Delta$}$_{g}$) 1.27 {$\mu$}m volume
emission rates (VER). We also present the first detection of much
({\times}80 {\plusmn} 20) weaker 1.58 {$\mu$}m (0-1) band emission from
Mars O$_{2}$($^{1}${$\Delta$}$_{g}$). Co-located polar
night CRISM O$_{2}$($^{1}${$\Delta$}$_{g}$) and Mars
Climate Sounder (MCS) (McCleese et al., 2008) temperature profiles are
compared to the same profiles as simulated by the Laboratoire de
Météorologie Dynamique (LMD) general
circulation/photochemical model (e.g., Lefèvre et al., 2004).
Both standard and interactive aerosol LMD simulations (Madeleine et al.,
2011a) underproduce CRISM O$_{2}$($^{1}${$\Delta$}$_{g}$)
total emission rates by 40\%, due to inadequate transport of atomic
oxygen to the winter polar emission regions. Incorporation of
interactive cloud radiative forcing on the global circulation leads to
distinct but insufficient improvements in modeled polar
O$_{2}$($^{1}${$\Delta$}$_{g}$) and temperatures. The
observed and modeled anti-correlations between temperatures and 1.27
{$\mu$}m band VER reflect the temperature dependence of the rate
coefficient for O$_{2}$($^{1}${$\Delta$}$_{g}$)
formation, as provided in Roble (1995).
  doi = {10.1029/2011JE004018},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Schorghofer}, N. and {Forget}, F.},
  title = {{History and anatomy of subsurface ice on Mars}},
  journal = {\icarus},
  year = 2012,
  volume = 220,
  pages = {1112-1120},
  abstract = {{Ice buried beneath a thin layer of soil has been revealed by neutron
spectroscopy and explored by the Phoenix Mars Lander. It has also been
exposed by recent impacts. This subsurface ice is thought to lose and
gain volume in response to orbital variations (Milankovitch cycles). We
use a powerful numerical model to follow the growth and retreat of
near-surface ice as a result of regolith-atmosphere exchange
continuously over millions of years. If a thick layer of almost pure ice
has been deposited recently, it has not yet reached equilibrium with the
atmospheric water vapor and may still remain as far equatorward as
43{\deg}N, where ice has been revealed by recent impacts. A potentially
observable consequence is present-day humidity output from the still
retreating ice. We also demonstrate that in a sublimation environment,
subsurface pore ice can accumulate in two ways. The first mode, widely
known, is the progressive filling of pores by ice over a range of
depths. The second mode occurs on top of an already impermeable ice
layer; subsequent ice accumulates in the form of pasted on horizontal
layers such that beneath the ice table, the pores are completely full
with ice. Most or all of the pore ice on Mars today may be of the second
type. At the Phoenix landing site, where such a layer is also expected
to exist above an underlying ice sheet, it may be extremely thin, due to
exceptionally small variations in ice stability over time.
  doi = {10.1016/j.icarus.2012.07.003},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Altieri}, F. and {Spiga}, A. and {Zasova}, L. and {Bellucci}, G. and 
	{Bibring}, J.-P.},
  title = {{Gravity waves mapped by the OMEGA/MEX instrument through O$_{2}$ dayglow at 1.27 {$\mu$}m: Data analysis and atmospheric modeling}},
  journal = {Journal of Geophysical Research (Planets)},
  keywords = {Atmospheric Composition and Structure: Airglow and aurora, Atmospheric Composition and Structure: Planetary atmospheres (5210, 5405, 5704), Atmospheric Processes: Mesoscale meteorology, Planetary Sciences: Solid Surface Planets: Remote sensing, Planetary Sciences: Solar System Objects: Mars},
  year = 2012,
  volume = 117,
  eid = {E00J08},
  pages = {E00J08},
  abstract = {{We present the occurrence of waves patterns on the southern polar region
of Mars as traced by the O$_{2}$ dayglow emission at {$\lambda$} =
1.27 {$\mu$}m during late winter/early spring of MY 28. The observations
were carried out by the OMEGA (Observatoire pour la Minéralogie,
l'Eau, les Glaces et l'Activité) imaging spectrometer on board
Mars Express (MEX). Waves are found preferentially at high incidence
angles and latitudes between 55{\deg} and 75{\deg}S. The dayglow intensity
fluctuations are of the order of {\plusmn}3\% at incidence angle
$\lt$88.5{\deg} and they can be explained by the propagation of gravity
waves in the Martian atmosphere. Mesoscale meteorological modeling
predicts gravity wave activity in the same range of latitude as the
observed O$_{2}$(a$^{1}${$\Delta$}$_{g}$) wave patterns
with temperature oscillations consistent with existing measurements.
Moreover, gravity waves simulated through mesoscale modeling can induce
dayglow fluctuations of the same order-of-magnitude as observed in the
OMEGA maps. This study confirms that airglow imagery is a powerful
method to detect and study the bi-dimensional propagation of gravity
waves, as foreseen in previous studies coupling photochemical and
dynamical models.
  doi = {10.1029/2012JE004065},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Oshchepkov}, S. and {Bril}, A. and {Yokota}, T. and {Morino}, I. and 
	{Yoshida}, Y. and {Matsunaga}, T. and {Belikov}, D. and {Wunch}, D. and 
	{Wennberg}, P. and {Toon}, G. and {O'Dell}, C. and {Butz}, A. and 
	{Guerlet}, S. and {Cogan}, A. and {Boesch}, H. and {Eguchi}, N. and 
	{Deutscher}, N. and {Griffith}, D. and {Macatangay}, R. and 
	{Notholt}, J. and {Sussmann}, R. and {Rettinger}, M. and {Sherlock}, V. and 
	{Robinson}, J. and {Kyr{\"o}}, E. and {Heikkinen}, P. and {Feist}, D.~G. and 
	{Nagahama}, T. and {Kadygrov}, N. and {Maksyutov}, S. and {Uchino}, O. and 
	{Watanabe}, H.},
  title = {{Effects of atmospheric light scattering on spectroscopic observations of greenhouse gases from space: Validation of PPDF-based CO$_{2}$ retrievals from GOSAT}},
  journal = {Journal of Geophysical Research (Atmospheres)},
  keywords = {GOSAT, Atmospheric Composition and Structure: Cloud/radiation interaction, Atmospheric Composition and Structure: Troposphere: composition and chemistry, Biogeosciences: Remote sensing, Computational Geophysics: Instruments and techniques},
  year = 2012,
  volume = 117,
  number = d16,
  eid = {D12305},
  pages = {D12305},
  abstract = {{This report describes a validation study of Greenhouse gases Observing
Satellite (GOSAT) data processing using ground-based measurements of the
Total Carbon Column Observing Network (TCCON) as reference data for
column-averaged dry air mole fractions of atmospheric carbon dioxide
(X$_{CO2}$). We applied the photon path length probability density
function method to validate X$_{CO2}$retrievals from GOSAT data
direct evaluation of optical path modifications due to atmospheric light
scattering that would have a negligible impact on ground-based TCCON
measurements but could significantly affect gas retrievals when
observing reflected sunlight from space. Our results reveal effects of
optical path lengthening over Northern Hemispheric stations, essentially
from May-September of each year, and of optical path shortening for
sun-glint observations in tropical regions. These effects are supported
by seasonal trends in aerosol optical depth derived from an offline
three-dimensional aerosol transport model and by cirrus optical depth
derived from space-based measurements of the Cloud-Aerosol Lidar with
Orthogonal Polarization (CALIOP) instrument. Removal of observations
that were highly contaminated by aerosol and cloud from the GOSAT data
set resulted in acceptable agreement in the seasonal variability of
X$_{CO2}$ over each station as compared with TCCON measurements.
Statistical comparisons between GOSAT and TCCON coincident measurements
of CO$_{2}$column abundance show a correlation coefficient of
0.85, standard deviation of 1.80 ppm, and a sub-ppm negative bias of
retrieved X$_{CO2}$ with a spatial resolution of 2.5{\deg} latitude
{\times} 2.5{\deg} longitude show agreement within {\tilde}2.5 ppm with
those predicted by the atmospheric tracer transport model.
  doi = {10.1029/2012JD017505},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Reuter}, M. and {Buchwitz}, M. and {Schneising}, O. and {Hase}, F. and 
	{Heymann}, J. and {Guerlet}, S. and {Cogan}, A.~J. and {Bovensmann}, H. and 
	{Burrows}, J.~P.},
  title = {{A simple empirical model estimating atmospheric CO$_{2}$ background concentrations}},
  journal = {Atmospheric Measurement Techniques},
  year = 2012,
  volume = 5,
  pages = {1349-1357},
  abstract = {{A simple empirical CO$_{2}$ model (SECM) is presented to estimate
column-average dry-air mole fractions of atmospheric CO$_{2}$
(XCO$_{2}$) as well as mixing ratio profiles. SECM is based on a
simple equation depending on 17 empirical parameters, latitude, and
date. The empirical parameters have been determined by least squares
fitting to NOAA's (National Oceanic and Atmospheric Administration)
assimilation system CarbonTracker version 2010 (CT2010). Comparisons
with TCCON (total carbon column observing network) FTS (Fourier
transform spectrometer) measurements show that SECM XCO$_{2}$
agrees quite well with reality. The synthetic XCO$_{2}$ values
have a standard error of 1.39 ppm and systematic station-to-station
biases of 0.46 ppm. Typical column averaging kernels of the TCCON FTS, a
SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric
CHartographY), and two GOSAT (Greenhouse gases Observing SATellite)
XCO$_{2}$ retrieval algorithms have been used to assess the
smoothing error introduced by using SECM profiles instead of CT2010
profiles as a priori. The additional smoothing error amounts to 0.17 ppm
for a typical SCIAMACHY averaging kernel and is most times much smaller
for the other instruments (e.g. 0.05 ppm for a typical TCCON FTS
averaging kernel). Therefore, SECM is well suited to provide a priori
information for state-of-the-art ground-based (FTS) and satellite-based
(GOSAT, SCIAMACHY) XCO$_{2}$ retrievals. Other potential
applications are: (i) near real-time processing systems (that cannot
make use of models like CT2010 operated in delayed mode), (ii)
``CO$_{2}$ proxy'' methods for XCH$_{4}$ retrievals (as
correction for the XCO$_{2}$ background), and (iii) observing
system simulation experiments especially for future satellite missions.
  doi = {10.5194/amt-5-1349-2012},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Madeleine}, J.-B. and {Forget}, F. and {Spiga}, A. and {Wolff}, M.~J. and 
	{Montmessin}, F. and {Vincendon}, M. and {Jouglet}, D. and {Gondet}, B. and 
	{Bibring}, J.-P. and {Langevin}, Y. and {Schmitt}, B.},
  title = {{Aphelion water-ice cloud mapping and property retrieval using the OMEGA imaging spectrometer onboard Mars Express}},
  journal = {Journal of Geophysical Research (Planets)},
  keywords = {Atmospheric Composition and Structure: Planetary atmospheres (5210, 5405, 5704), Biogeosciences: Remote sensing, Mathematical Geophysics: Spectral analysis (3205, 3280, 4319), Atmospheric Processes: Clouds and aerosols, Planetary Sciences: Solar System Objects: Mars},
  year = 2012,
  volume = 117,
  eid = {E00J07},
  pages = {E00J07},
  abstract = {{Mapping of the aphelion clouds over the Tharsis plateau and retrieval of
their particle size and visible opacity are made possible by the OMEGA
imaging spectrometer aboard Mars Express. Observations cover the period
from MY26 L$_{s}$ = 330{\deg} to MY29 L$_{s}$ = 180{\deg} and
are acquired at various local times, ranging from 8 AM to 6 PM. Cloud
maps of the Tharsis region constructed using the 3.1 {$\mu$}m ice
absorption band reveal the seasonal and diurnal evolution of aphelion
clouds. Four distinct types of clouds are identified: morning hazes,
topographically controlled hazes, cumulus clouds and thick hazes. The
location and time of occurrence of these clouds are analyzed and their
respective formation process is discussed. An inverse method for
retrieving cloud particle size and opacity is then developed and can
only be applied to thick hazes. The relative error of these measurements
is less than 30\% for cloud particle size and 20\% for opacity. Two groups
of particles can be distinguished. The first group is found over flat
plains and is composed of relatively small particles, ranging in size
from 2 to 3.5 {$\mu$}m. The second group is characterized by particle sizes
of {\tilde}5 {$\mu$}m which appear to be quite constant over L$_{s}$
and local time. It is found west of Ascraeus and Pavonis Mons, and near
Lunae Planum. These regions are preferentially exposed to anabatic
winds, which may control the formation of these particles and explain
their distinct properties. The water ice column is equal to 2.9 pr.{$\mu$}m
on average, and can reach 5.2 pr.{$\mu$}m in the thickest clouds of
  doi = {10.1029/2011JE003940},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Schepers}, D. and {Guerlet}, S. and {Butz}, A. and {Landgraf}, J. and 
	{Frankenberg}, C. and {Hasekamp}, O. and {Blavier}, J.-F. and 
	{Deutscher}, N.~M. and {Griffith}, D.~W.~T. and {Hase}, F. and 
	{Kyro}, E. and {Morino}, I. and {Sherlock}, V. and {Sussmann}, R. and 
	{Aben}, I.},
  title = {{Methane retrievals from Greenhouse Gases Observing Satellite (GOSAT) shortwave infrared measurements: Performance comparison of proxy and physics retrieval algorithms}},
  journal = {Journal of Geophysical Research (Atmospheres)},
  keywords = {GOSAT, methane, retrieval, Atmospheric Composition and Structure: Radiation: transmission and scattering, Atmospheric Composition and Structure: Instruments and techniques},
  year = 2012,
  volume = 117,
  number = d16,
  eid = {D10307},
  pages = {D10307},
  abstract = {{We compare two conceptually different methods for determining methane
column-averaged mixing ratios ? from Greenhouse Gases Observing
Satellite (GOSAT) shortwave infrared (SWIR) measurements. These methods
account differently for light scattering by aerosol and cirrus. The
proxy method retrieves a CO$_{2}$ column which, in conjunction
with prior knowledge on CO$_{2}$acts as a proxy for scattering
effects. The physics-based method accounts for scattering by retrieving
three effective parameters of a scattering layer. Both retrievals are
the Total Carbon Column Observing Network (TCCON), showing comparable
performance: for the proxy retrieval we find station-dependent retrieval
biases from -0.312\% to 0.421\% of ? a standard deviation of 0.22\% and a
typical precision of 17 ppb. The physics method shows biases between
-0.836\% and -0.081\% with a standard deviation of 0.24\% and a precision
similar to the proxy method. Complementing this validation we compared
both retrievals with simulated methane fields from a global
chemistry-transport model. This identified shortcomings of both
retrievals causing biases of up to 1ings and provide a satisfying
validation of any methane retrieval from space-borne SWIR measurements,
in our opinion it is essential to further expand the network of TCCON
  doi = {10.1029/2012JD017549},
  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 ancient explosive volcanoes on Mars: Implications for the friable layered deposits}},
  journal = {\icarus},
  year = 2012,
  volume = 219,
  pages = {358-381},
  abstract = {{A number of voluminous, fine-grained, friable deposits have been mapped
on Mars. The modes of origin for these deposits are debated. The
feasibility for an origin by volcanic airfall for the friable deposits
is tested using a global circulation model to simulate the dispersal of
pyroclasts from candidate source volcanoes near each deposit. It is
concluded that the Medusae Fossae Formation and Electris deposits are
easily formed through volcanic processes, and that the Hellas deposits
and south polar pitted deposits could have some contribution from
volcanic sources in specific atmospheric regimes. The Arabia and Argyre
deposits are not well replicated by modeled pyroclast dispersal,
suggesting that these deposits were most likely emplaced by other means.
  doi = {10.1016/j.icarus.2012.03.016},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Fastook}, J.~L. and {Head}, J.~W. and {Marchant}, D.~R. and 
	{Forget}, F. and {Madeleine}, J.-B.},
  title = {{Early Mars climate near the Noachian-Hesperian boundary: Independent evidence for cold conditions from basal melting of the south polar ice sheet (Dorsa Argentea Formation) and implications for valley network formation}},
  journal = {\icarus},
  year = 2012,
  volume = 219,
  pages = {25-40},
  abstract = {{Currently, and throughout much of the Amazonian, the mean annual surface
temperatures of Mars are so cold that basal melting does not occur in
ice sheets and glaciers and they are cold-based. The documented evidence
for extensive and well-developed eskers (sediment-filled former
sub-glacial meltwater channels) in the south circumpolar Dorsa Argentea
Formation is an indication that basal melting and wet-based glaciation
occurred at the South Pole near the Noachian-Hesperian boundary. We
employ glacial accumulation and ice-flow models to distinguish between
basal melting from bottom-up heat sources (elevated geothermal fluxes)
and top-down induced basal melting (elevated atmospheric temperatures
warming the ice). We show that under mean annual south polar atmospheric
temperatures (-100 {\deg}C) simulated in typical Amazonian climate
experiments and typical Noachian-Hesperian geothermal heat fluxes (45-65
mW/m$^{2}$), south polar ice accumulations remain cold-based. In
order to produce significant basal melting with these typical geothermal
heat fluxes, the mean annual south polar atmospheric temperatures must
be raised from today's temperature at the surface (-100 {\deg}C) to the
range of -50 to -75 {\deg}C. This mean annual polar surface atmospheric
temperature range implies lower latitude mean annual temperatures that
are likely to be below the melting point of water, and thus does not
favor a ``warm and wet'' early Mars. Seasonal temperatures at lower
latitudes, however, could range above the melting point of water,
perhaps explaining the concurrent development of valley networks and
open basin lakes in these areas. This treatment provides an independent
estimate of the polar (and non-polar) surface temperatures near the
Noachian-Hesperian boundary of Mars history and implies a cold and
relatively dry Mars climate, similar to the Antarctic Dry Valleys, where
seasonal melting forms transient streams and permanent ice-covered lakes
in an otherwise hyperarid, hypothermal climate.
  doi = {10.1016/j.icarus.2012.02.013},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Hébrard}, E. and {Listowski}, C. and {Coll}, P. and {Marticorena}, B. and 
	{Bergametti}, G. and {M{\"a}{\"a}tt{\"a}nen}, A. and {Montmessin}, F. and 
	{Forget}, F.},
  title = {{An aerodynamic roughness length map derived from extended Martian rock abundance data}},
  journal = {Journal of Geophysical Research (Planets)},
  keywords = {Atmospheric Processes: Boundary layer processes, Atmospheric Processes: Global climate models (1626, 4928), Planetary Sciences: Solid Surface Planets: Atmospheres (0343, 1060), Planetary Sciences: Solid Surface Planets: Surface materials and properties, Planetary Sciences: Solar System Objects: Mars},
  year = 2012,
  volume = 117,
  eid = {E04008},
  pages = {E04008},
  abstract = {{Many boundary layer processes simulated within a Mars General
Circulation Model (MGCM), including the description of the processes
controlling dust rising from the Martian surface, are highly sensitive
to the aerodynamic roughness length z$_{0}$. On the basis of
rock-size frequency distributions inferred from different Martian
landing sites and Earth analog sites, we have first established that
lognormal-modeled rock-size frequency distributions are able to
reproduce correctly the observed Martian rock populations. We have
validated the hypothesis that the rock abundance {$\zeta$} of a given area
could be estimated at a first order from its thermophysical properties,
namely its thermal inertia I and its albedo {$\alpha$}. We have
demonstrated the possibility of using rock abundance {$\zeta$} to estimate
the roughness density {$\lambda$} on Mars and to retrieve subsequently the
aerodynamic roughness length by using semi-empirical relationships based
on terrestrial wind-tunnel and field measurements. By combining our
methodology with remote sensing measurements of the Thermal Emission
Spectrometer aboard Mars Global Surveyor, we have derived a global map
of the aeolian aerodynamic roughness length with a 1/8{\deg} {\times}
1/8{\deg} resolution over the entire Martian surface. Contrary to what is
often assumed, the Martian aeolian aerodynamic roughness length is
spatially highly heterogeneous. At the fullest resolution, the Martian
aerodynamic roughness length varies from 10$^{-3}$ cm to 2.33 cm.
About 84\% of the Martian surface seems to be characterized by an aeolian
aerodynamic roughness length value lower than 1 cm, the spatially
uniform value that most of the MGCMs simulations have assumed recently.
Since the aerodynamic roughness length z$_{0}$ is a key parameter
in deriving the erosion threshold wind velocities, we anticipate a
significant impact of our findings on the efficiencies for lifting dust
in future MGCMs.
  doi = {10.1029/2011JE003942},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Sprague}, A.~L. and {Boynton}, W.~V. and {Forget}, F. and {Lian}, Y. and 
	{Richardson}, M. and {Starr}, R. and {Metzger}, A.~E. and {Hamara}, D. and 
	{Economou}, T.},
  title = {{Interannual similarity and variation in seasonal circulation of Mars' atmospheric Ar as seen by the Gamma Ray Spectrometer on Mars Odyssey}},
  journal = {Journal of Geophysical Research (Planets)},
  keywords = {Atmospheric Composition and Structure: Constituent sources and sinks, Atmospheric Composition and Structure: Middle atmosphere: constituent transport and chemistry (3334), Atmospheric Composition and Structure: Planetary atmospheres (5210, 5405, 5704), Biogeosciences: Climate dynamics (1620), Atmospheric Processes: General circulation (1223)},
  year = 2012,
  volume = 117,
  eid = {E04005},
  pages = {E04005},
  abstract = {{More than 3 Mars' years (MY) of atmospheric argon (Ar) measurements are
used to study annual and seasonal variations in atmospheric transport
and mixing. Data are obtained over the period 20 May 2002 to 4 May 2008
by the Gamma Subsystem (GS) of the Gamma Ray Spectrometer (GRS) on the
Mars Odyssey spacecraft in orbit around Mars. Here we augment previous
studies of Mars' Ar in which strong seasonal variations were observed
and horizontal meridional mixing coefficients for the southern
hemisphere were computed. Comparison of year-to-year seasonal abundance
shows strong similarity but also some short-period
({\tilde}15{\deg}-30{\deg} L$_{s}$) and interannual variations.
Evidence for short periods of strong eddy transport is exhibited during
autumn and winter. The seasonal change in Ar concentration for southern
latitudes is relatively gradual and well defined, but seasonal changes
at high northern latitudes are chaotic and indicate that atmospheric
disturbance is ubiquitous. Major topographic landforms (Elysium,
Tharsis, Noachis Terra, Hellas) apparently have little control over
seasonal Ar concentration at the spatial resolution of the GRS data set.
Some indication of local enhanced Ar concentration is present from
30{\deg}N to 60{\deg}N for the Hellas and Tharsis sectors in late winter
and early spring. The data show some significant (3{$\sigma$}) differences
between MY 26 and MY 27 in geographical sectors that are likely produced
by local weather. The GS data do not show seasonal variation of Ar at
equatorial and low-latitude zones, in contrast to those from the Alpha
Particle X-ray Spectrometer (APXS) measurements from the Mars
Exploration Rovers.
  doi = {10.1029/2011JE003873},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Wilson}, C.~F. and {Chassefière}, E. and {Hinglais}, E. and 
	{Baines}, K.~H. and {Balint}, T.~S. and {Berthelier}, J.-J. and 
	{Blamont}, J. and {Durry}, G. and {Ferencz}, C.~S. and {Grimm}, R.~E. and 
	{Imamura}, T. and {Josset}, J.-L. and {Leblanc}, F. and {Lebonnois}, S. and 
	{Leitner}, J.~J. and {Limaye}, S.~S. and {Marty}, B. and {Palomba}, E. and 
	{Pogrebenko}, S.~V. and {Rafkin}, S.~C.~R. and {Talboys}, D.~L. and 
	{Wieler}, R. and {Zasova}, L.~V. and {Szopa}, C.},
  title = {{The 2010 European Venus Explorer (EVE) mission proposal}},
  journal = {Experimental Astronomy},
  keywords = {Venus, Planetary mission, Cosmic vision, Superpressure balloon, Geochemistry, Dynamics},
  year = 2012,
  volume = 33,
  pages = {305-335},
  abstract = {{The European Venus Explorer (EVE) mission described in this paper was
proposed in December 2010 to ESA as an `M-class' mission under the
Cosmic Vision programme. It consists of a single balloon platform
floating in the middle of the main convective cloud layer of Venus at an
altitude of 55 km, where temperatures and pressures are benign
({\tilde}25{\deg}C and {\tilde}0.5 bar). The balloon float lifetime would
be at least 10 Earth days, long enough to guarantee at least one full
circumnavigation of the planet. This offers an ideal platform for the
two main science goals of the mission: study of the current climate
through detailed characterization of cloud-level atmosphere, and
investigation of the formation and evolution of Venus, through careful
measurement of noble gas isotopic abundances. These investigations would
provide key data for comparative planetology of terrestrial planets in
our solar system and beyond.
  doi = {10.1007/s10686-011-9259-9},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Lebonnois}, S. and {Burgalat}, J. and {Rannou}, P. and {Charnay}, B.
  title = {{Titan global climate model: A new 3-dimensional version of the IPSL Titan GCM}},
  journal = {\icarus},
  year = 2012,
  volume = 218,
  pages = {707-722},
  abstract = {{We have developed a new 3-dimensional climate model for Titan{\rsquo}s
atmosphere, using the physics of the IPSL Titan 2-dimensional climate
model with the current version of the LMDZ General Circulation Model
dynamical core. Microphysics and photochemistry are still computed as
zonal averages. This GCM covers altitudes from surface to 500 km
altitude, with barotropic waves now being resolved and the diurnal cycle
included. The boundary layer scheme has been changed, yielding a strong
improvement in the tropospheric zonal wind profile modeled at Huygens
descent position and season. The potential temperature profile is fairly
consistent with Huygens observations in the lowest 10 km. The
latitudinal profile of the near-surface temperature is close to observed
values. The minimum of zonal wind observed by the Huygens probe just
above the tropopause is also present in these simulations, and its
origin is discussed by comparing solar heating and dynamical transport
of energy. The stratospheric temperature and wind fields are consistent
with our previous works. Compared to observations, the zonal wind peak
is too weak (around 120 m/s) and too low (around 200 km). The
temperature structures appear to be compressed in altitude, and depart
strongly from observations in the upper stratosphere. These
discrepancies are correlated, and most probably related to the altitude
of the haze production. The model produces a detached haze layer located
more than 150 km lower than observed by the Cassini instruments. This
low production altitude is due to the current position of the GCM upper
boundary. However, the temporal behaviour of the detached haze layer in
the model may explain the seasonal differences observed between Cassini
and Voyager 1. The waves present in the GCM are analyzed, together with
their respective roles in the angular momentum budget. Though the role
of the mean meridional circulation in momentum transport is similar to
previous work, and the transport by barotropic waves is clearly seen in
the stratosphere, a significant part of the transport at high latitudes
is done all year long through low-frequency tropospheric waves that may
be baroclinic waves.
  doi = {10.1016/j.icarus.2011.11.032},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Cordier}, D. and {Mousis}, O. and {Lunine}, J.~I. and {Lebonnois}, S. and 
	{Rannou}, P. and {Lavvas}, P. and {Lobo}, L.~Q. and {Ferreira}, A.~G.~M.
  title = {{Titan's lakes chemical composition: Sources of uncertainties and variability}},
  journal = {\planss},
  archiveprefix = {arXiv},
  eprint = {1104.2131},
  primaryclass = {astro-ph.EP},
  year = 2012,
  volume = 61,
  pages = {99-107},
  abstract = {{Between 2004 and 2007 the instruments of the Cassini spacecraft,
orbiting within the Saturn system, discovered dark patches in the polar
regions of Titan. These features are interpreted as hydrocarbon lakes
and seas with ethane and methane identified as the main compounds. In
this context, we have developed a lake-atmosphere equilibrium model
allowing the determination of the chemical composition of these liquid
areas present on Titan. The model is based on uncertain thermodynamic
data and precipitation rates of organic species predicted to be present
in the lakes and seas that are subject to spatial and temporal
variations. Here we explore and discuss the influence of these
uncertainties and variations. The errors and uncertainties relevant to
thermodynamic data are simulated via Monte Carlo simulations. Global
circulation models (GCM) are also employed in order to investigate the
possibility of chemical asymmetry between the south and the north poles,
due to differences in precipitation rates. We find that mole fractions
of compounds in the liquid phase have a high sensitivity to
thermodynamic data used as inputs, in particular molar volumes and
enthalpies of vaporization. When we combine all considered
uncertainties, the ranges of obtained mole fractions are rather large
(up to {\sim}8500\%) but the distributions of values are narrow. The
relative standard deviations remain between 10\% and {\sim}300\% depending
on the compound considered. Compared to other sources of uncertainties
and variability, deviation caused by surface pressure variations are
clearly negligible, remaining of the order of a few percent up to
{\sim}20\%. Moreover, no significant difference is found between the
composition of lakes located in north and south poles. Because the
theory of regular solutions employed here is sensitive to thermodynamic
data and is not suitable for polar molecules such as HCN and
CH$_{3}$CN, our work strongly underlines the need for experimental
simulations and the improvement of Titan's atmospheric models.
  doi = {10.1016/j.pss.2011.05.009},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Charnay}, B. and {Lebonnois}, S.},
  title = {{Two boundary layers in Titan's lower troposphere inferred from a climate model}},
  journal = {Nature Geoscience},
  year = 2012,
  volume = 5,
  pages = {106-109},
  abstract = {{Saturn's moon Titan has a dense atmosphere, but its thermal structure is
poorly known. Conflicting information has been gathered on the nature,
extent and evolution of Titan's planetary boundary layer--the layer of
the atmosphere that is influenced by the surface--from radio-occultation
observations by the Voyager 1 spacecraft and the Cassini orbiter,
measurements by the Huygens probe and by dune-spacing analyses.
Specifically, initial analyses of the Huygens data suggested a boundary
layer of 300m depth with no diurnal evolution, incompatible with
alternative estimates of 2-3km (refs , , ). Here we use a
three-dimensional general circulation model, albeit not explicitly
simulating the methane cycle, to analyse the dynamics leading to the
thermal profile of Titan's lowermost atmosphere. In our simulations, a
convective boundary layer develops in the course of the day, rising to
an altitude of 800m. In addition, a seasonal boundary of 2km depth is
produced by the reversal of the Hadley cell at the equinox, with a
dramatic impact on atmospheric circulation. We interpret fog that had
been discovered at Titan's south pole earlier as boundary layer clouds.
We conclude that Titan's troposphere is well structured, featuring two
boundary layers that control wind patterns, dune spacing and cloud
formation at low altitudes.
  doi = {10.1038/ngeo1374},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Migliorini}, A. and {Grassi}, D. and {Montabone}, L. and {Lebonnois}, S. and 
	{Drossart}, P. and {Piccioni}, G.},
  title = {{Investigation of air temperature on the nightside of Venus derived from VIRTIS-H on board Venus-Express}},
  journal = {\icarus},
  year = 2012,
  volume = 217,
  pages = {640-647},
  abstract = {{We present the spatial distribution of air temperature on Venus' night
side, as observed by the high spectral resolution channel of VIRTIS
(Visible and Infrared Thermal Imaging Spectrometer), or VIRTIS-H, on
board the ESA mission Venus Express. The present work extends the
investigation of the average thermal fields in the northern hemisphere
of Venus, by including the VIRTIS-H data. We show results in the
pressure range of 100-4 mbar, which corresponds to the altitude range of
65-80 km. With these new retrievals, we are able to compare the thermal
structure of the Venus' mesosphere in both hemispheres. The major
thermal features reported in previous investigations, i.e. the cold
collar at about 65-70{\deg}S latitude, 100 mbar pressure level, and the
asymmetry between the evening and morning sides, are confirmed here. By
comparing the temperatures retrieved by the VIRTIS spectrometer in the
North and South we find that similarities exist between the two
hemispheres. Solar thermal tides are clearly visible in the average
temperature fields. To interpret the thermal tide signals (otherwise
impossible without day site observations), we apply model simulations
using the Venus global circulation model Venus GCM (Lebonnois, S.,
Hourdin, F., Forget, F., Eymet, V., Fournier, R. [2010b]. International
Venus Conference, Aussois, 20-26 June 2010) of the Laboratoire de
Météorologie Dynamique (LMD). We suggest that the signal
detected at about 60-70{\deg} latitude and pressure of 100 mbar is a
diurnal component, while those located at equatorial latitudes are
semi-diurnal. Other tide-related features are clearly identified in the
upper levels of the atmosphere.
  doi = {10.1016/j.icarus.2011.07.013},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Massé}, M. and {Bourgeois}, O. and {Le Mouélic}, S. and 
	{Verpoorter}, C. and {Spiga}, A. and {Le Deit}, L.},
  title = {{Wide distribution and glacial origin of polar gypsum on Mars}},
  journal = {Earth and Planetary Science Letters},
  year = 2012,
  volume = 317,
  pages = {44-55},
  abstract = {{The North Polar Cap of Mars is associated with different kinds of
superficial sediments, including the Circumpolar Dune Field, interior
dune fields and sedimentary veneers scattered over the ice cap. In order
to resolve the mineralogical composition and the regional distribution
of these sediments, we processed OMEGA and CRISM hyperspectral data with
an original method based on spectral derivation. We find that gypsum is
present in all areas where undefined hydrated minerals had been
previously detected, including superficial sedimentary veneers covering
the North Polar Cap, interior dune fields and the whole Circumpolar Dune
Field. Morphological and structural analyses reveal that these gypsum
crystals derive directly from the interior of the ice cap. The source of
superficial sedimentary veneers is the dust that was previously
contained in the upper part of the ice cap, the ice-rich North Polar
Layered Deposits (NPLD). This gypsum-bearing dust was released, on
south-facing slopes of spiral troughs and arcuate scarps, by ice
ablation controlled by katabatic winds. By the analysis of all
associations of erosional scarps and dune fields over the North Polar
Cap, we also demonstrate that the polar dunes are composed of sand-sized
particles that were previously contained in the sediment-rich Basal Unit
(BU), corresponding to the lower part of the ice cap. These particles
contain gypsum and were released from the BU, by regressive ablation of
ice at marginal scarps that border the North Polar Cap and by vertical
ablation of ice on Olympia Planum. From a reconstruction of wind
streamlines over and around the ice cap, we infer that katabatic winds
descending from the polar high and rotating around the North Polar Cap
control the release of these gypsum-bearing particles by ice ablation
and the redistribution of these particles in the Circumpolar Dune Field.
  doi = {10.1016/j.epsl.2011.11.035},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Spiga}, A. and {Gonz{\'a}lez-Galindo}, F. and {L{\'o}pez-Valverde}, M.-{\'A}. and 
	{Forget}, F.},
  title = {{Gravity waves, cold pockets and CO$_{2}$ clouds in the Martian mesosphere}},
  journal = {\grl},
  keywords = {Atmospheric Composition and Structure: Planetary atmospheres (5210, 5405, 5704), Atmospheric Processes: Clouds and aerosols, Atmospheric Processes: Mesoscale meteorology, Atmospheric Processes: Acoustic-gravity waves, Planetary Sciences: Solar System Objects: Mars},
  year = 2012,
  volume = 39,
  eid = {L02201},
  pages = {L02201},
  abstract = {{Many independent measurements have shown that extremely cold
temperatures are found in the Martian mesosphere. These mesospheric
{\ldquo}cold pockets{\rdquo} may result from the propagation of
atmospheric waves. Recent observational achievements also hint at such
cold pockets by revealing mesospheric clouds formed through the
condensation of CO$_{2}$, the major component of the Martian
atmosphere. Thus far, modeling studies addressing the presence of cold
pockets in the Martian mesosphere have explored the influence of
large-scale circulations. Mesoscale phenomena, such as gravity waves,
have received less attention. Here we show through multiscale
meteorological modeling that mesoscale gravity waves could play a key
role in the formation of mesospheric cold pockets propitious to
CO$_{2}$ condensation.
  doi = {10.1029/2011GL050343},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}