@comment{{This file has been generated by bib2bib 1.94}}
@comment{{Command line: /usr/bin/bib2bib --quiet -c 'not journal:"Discussions"' -c year=2019 -c $type="ARTICLE" -oc pub2019.txt -ob pub2019.bib}}
  author = {{Vals}, M. and {Spiga}, A. and {Forget}, F. and {Millour}, E. and 
	{Montabone}, L. and {Lott}, F.},
  title = {{Study of gravity waves distribution and propagation in the thermosphere of Mars based on MGS, ODY, MRO and MAVEN density measurements}},
  journal = {\planss},
  archiveprefix = {arXiv},
  eprint = {1901.04338},
  primaryclass = {astro-ph.EP},
  year = 2019,
  volume = 178,
  eid = {104708},
  pages = {104708},
  abstract = {{By measuring the regular oscillations of the density of CO$_{2}$
in the upper atmosphere (between 120 and 190 km), the mass spectrometer
MAVEN/NGIMS (Atmosphere and Volatile EvolutioN/Neutral Gas Ion Mass
Spectrometer) reveals the local impact of gravity waves. This yields
precious information on the activity of gravity waves and the
atmospheric conditions in which they propagate and break. The intensity
of gravity waves measured by MAVEN in the upper atmosphere has been
shown to be dictated by saturation processes in isothermal conditions.
As a result, gravity waves activity is correlated to the evolution of
the inverse of the background temperature. Previous data gathered at
lower altitudes ({\sim} 95- {\sim} 150 km) during aerobraking by the
accelerometers on board MGS (Mars Global Surveyor), ODY (Mars Odyssey)
and MRO (Mars Reconnaissance Orbiter) are analyzed in the light of those
recent findings with MAVEN. The anti-correlation between GW-induced
density perturbations and background temperature is plausibly found in
the ODY data acquired in the polar regions, but not in the MGS and MRO
data. MRO data in polar regions exhibit a correlation between the
density perturbations and the Brunt-V{\"a}is{\"a}l{\"a} frequency
(or, equivalently, static stability), obtained from Global Climate
Modeling compiled in the Mars Climate Database. At lower altitude levels
(between 100 and 120 km), although wave saturation might still be
dominant, isothermal conditions are no longer verified. In this case,
theory predicts that the intensity of gravity waves is no more
correlated to background temperature, but to static stability. At other
latitudes in the three aerobraking datasets, the GW-induced relative
density perturbations are correlated with neither inverse temperature
nor static stability; in this particular case, this means that the
observed activity of gravity waves is not only controlled by saturation,
but also by the effects of gravity-wave sources and wind filtering
through critical levels. This result highlights the exceptional nature
of MAVEN/NGIMS observations which combine both isothermal and saturated
conditions contrary to aerobraking measurements.
  doi = {10.1016/j.pss.2019.104708},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{P{\'a}l}, B. and {Kereszturi}, {\'A}. and {Forget}, F. and 
	{Smith}, M.~D.},
  title = {{Global seasonal variations of the near-surface relative humidity levels on present-day Mars}},
  journal = {\icarus},
  archiveprefix = {arXiv},
  eprint = {1902.07772},
  primaryclass = {astro-ph.EP},
  keywords = {Mars, Liquid water, Relative humidity, Habitability, Atmospheric modelling},
  year = 2019,
  volume = 333,
  pages = {481-495},
  abstract = {{We investigate the global seasonal variations of near-surface relative
humidity and relevant attributes, like temperature and water vapor
volume mixing ratio on Mars using calculations from modelled and
measurement data. We focus on 2 AM local time snapshots to eliminate
daily effects related to differences in insolation, and to be able to
compare calculations based on modelling data from the Laboratoire de
Météorologie Dynamique Mars General Circulation Model with
the observations of Mars Global Surveyor Thermal Emission Spectrometer.
We study the seasonal effects by examining four specific dates in the
Martian year, the northern spring equinox, summer solstice, autumn
equinox, and winter solstice. We identify three specific zones, where
the near-surface relative humidity levels are systematically higher than
in their vicinity regardless of season. We find that these areas
coincide with low thermal inertia features, which control surface
temperatures on the planet, and are most likely covered with
unconsolidated fine dust with grain sizes smaller than {\sim} 40 {$\mu$}m.
By comparing the data of relative humidity, temperature and water vapor
volume mixing ratio at three different heights (near-surface, {\sim} 4 m
and {\sim} 23 m above the surface), we demonstrate that the thermal
inertia could play an important role in determining near-surface
humidity levels. We also notice that during the night the water vapor
levels drop at {\sim} 4 m above the surface. This, together with the
temperature and thermal inertia values, shows that water vapor likely
condenses in the near-surface atmosphere and on the ground during the
night at the three aforementioned regions. This condensation may be in
the form of brines, wettening of the fine grains by adsorption or
deliquescence. This study specifies areas of interest on the surface of
present day Mars for the proposed condensation, which may be examined by
in-situ measurements in the future.
  doi = {10.1016/j.icarus.2019.07.007},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Lora}, J.~M. and {Tokano}, T. and {Vatant d'Ollone}, J. and 
	{Lebonnois}, S. and {Lorenz}, R.~D.},
  title = {{A model intercomparison of Titan's climate and low-latitude environment}},
  journal = {\icarus},
  keywords = {Titan, Climate, Atmospheres, Meteorology},
  year = 2019,
  volume = 333,
  pages = {113-126},
  abstract = {{Cassini-Huygens provided a wealth of data with which to constrain
numerical models of Titan. Such models have been employed over the last
decade to investigate various aspects of Titan's atmosphere and climate,
and several three-dimensional general circulation models (GCMs) now
exist that simulate Titan with a high degree of fidelity. However,
substantial uncertainties persist, and at the same time no dedicated
intercomparisons have assessed the degree to which these models agree
with each other or the observations. To address this gap, and motivated
by the proposed Dragonfly Titan lander mission, we directly compare
three Titan GCMs to each other and to in situ observations, and also
provide multi-model expectations for the low-latitude environment during
the early northern winter season. Globally, the models qualitatively
agree in their representation of the atmospheric structure and
circulation, though one model severely underestimates meridional
temperature gradients and zonal winds. We find that, at low latitudes,
simulated and observed atmospheric temperatures closely agree in all
cases, while the measured winds above the boundary layer are only
quantitatively matched by one model. Nevertheless, the models simulate
similar near-surface winds, and all indicate these are weak. Likewise,
temperatures and methane content at low latitudes are similar between
models, with some differences that are largely attributable to modeling
assumptions. All models predict environments that closely resemble that
encountered by the Huygens probe, including little or no precipitation
at low latitudes during northern winter. The most significant
differences concern the methane cycle, though the models are least
comparable in this area and substantial uncertainties remain. We suggest
that, while the overall low-latitude environment on Titan at this season
is now fairly well constrained, future in situ measurements and
monitoring will transform our understanding of regional and temporal
variability, atmosphere-surface coupling, Titan's methane cycle, and
modeling thereof.
  doi = {10.1016/j.icarus.2019.05.031},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Wolff}, M.~J. and {Clancy}, R.~T. and {Kahre}, M.~A. and {Haberle}, R.~M. and 
	{Forget}, F. and {Cantor}, B.~A. and {Malin}, M.~C.},
  title = {{Mapping water ice clouds on Mars with MRO/MARCI}},
  journal = {\icarus},
  keywords = {Mars, Atmosphere, Ultraviolet observations, Radiative transfer},
  year = 2019,
  volume = 332,
  pages = {24-49},
  abstract = {{Observations by the Mars Color Imager (MARCI) onboard the Mars
Reconnaissance Orbiter (MRO) in the ultraviolet (UV, Band 7; 320 nm) are
used to characterize the spatial and temporal behavior of atmospheric
water ice over a period of 6 Mars Years. Exploiting the contrast of the
bright ice clouds to the low albedo surface, a radiative transfer-based
retrieval algorithm is developed to derive the column-integrated optical
depth of the ice ({$\tau$}$_{ice}$). Several relatively unique input
products are created as part of the retrieval development process,
including a zonal dust climatology based on emission phase function
(EPFs) sequences from the Compact Reconnaissance Imaging Spectrometer
for Mars (CRISM), a spatially variable UV-reflectance model for Band 7
(as well as for Band 6, 260 nm), and a water ice scattering phase
function based on a droxtal ice habit. Taking into account a radiometric
precision of 7\%, an error analysis estimates the uncertainty in
{$\tau$}$_{ice}$ to be {\sim}0.03 (excluding particle size effects,
which are discussed separately). Zonal trends are analyzed over the full
temporal extent of the observations, looking at both diurnal and
interannual variability. The main (zonal) features are the aphelion
cloud belt (ACB) and the polar hoods. For the ACB, there can be an
appreciable diurnal change in {$\tau$}$_{ice}$ between the periods of
14h30-15h00 and 15h00-15h30 Local True Solar Time (LTST). The amplitude
of this effect shows relatively large interannual variability,
associated mainly with changes in the earlier time block. When averaged
over the interval 14h00-16h00 LTST, the interannual differences in the
ACB structure are appreciably smaller. When the MARCI
{$\tau$}$_{ice}$ are compared to those from the Thermal Emission
Spectrometer (TES), there is a good correlation of features, with the
most significant difference being the seasonal (L$_{S}$) evolution
of the ACB. For TES, the ACB zonal profile is relative symmetric about
L$_{S}$ = 90{\deg}. In the MARCI data, this profile is noticeably
asymmetric, with the centroid shifted to later in the northern summer
season (L$_{S}$ = 120{\deg}). The MARCI behavior is consistent with
that observed by several other instruments. The correspondence of MARCI
{$\tau$}$_{ice}$ zonal and meridional behaviors with that predicted
by two Global Circulation Models (GCM) is good. Each model captures the
general behavior seen by MARCI in the ACB, the polar hoods, and the
major orographic/topographic cloud features (including Valles Mariners).
However, the mismatches between GCM results and MARCI reinforce the
challenging nature of water ice clouds for dynamical models. The
released {$\tau$}$_{ice}$ are being archived at Malin Space Science
Systems at\_marci\_iceclouds/.
  doi = {10.1016/j.icarus.2019.05.041},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Cavalié}, T. and {Hue}, V. and {Hartogh}, P. and {Moreno}, R. and 
	{Lellouch}, E. and {Feuchtgruber}, H. and {Jarchow}, C. and 
	{Cassidy}, T. and {Fletcher}, L.~N. and {Billebaud}, F. and 
	{Dobrijevic}, M. and {Rezac}, L. and {Orton}, G.~S. and {Rengel}, M. and 
	{Fouchet}, T. and {Guerlet}, S.},
  title = {{Herschel map of Saturn's stratospheric water, delivered by the plumes of Enceladus}},
  journal = {\aap},
  archiveprefix = {arXiv},
  eprint = {1908.07399},
  primaryclass = {astro-ph.EP},
  keywords = {planets and satellites: individual: Saturn, planets and satellites: individual: Enceladus, planets and satellites: atmospheres},
  year = 2019,
  volume = 630,
  eid = {A87},
  pages = {A87},
  abstract = {{Context. The origin of water in the stratospheres of giant planets has
been an outstanding question ever since its first detection by the
Infrared Space Observatory some 20 years ago. Water can originate from
interplanetary dust particles, icy rings and satellites, and large comet
impacts. Analyses of Herschel Space Observatory observations have proven
that the bulk of Jupiter's stratospheric water was delivered by the
Shoemaker-Levy 9 impacts in 1994. In 2006, the Cassini mission detected
water plumes at the South Pole of Enceladus, which made the moon a
serious candidate for Saturn's stratospheric water. Further evidence was
found in 2011 when Herschel demonstrated the presence of a water torus
at the orbital distance of Enceladus that was fed by the moon's plumes.
Finally, water falling from the rings onto Saturn's uppermost
atmospheric layers at low latitudes was detected during the final orbits
of Cassini's end-of-mission plunge into the atmosphere. 
Aims: In this paper, we use Herschel mapping observations of water in Saturn's stratosphere to identify its source.
Methods: We tested several empirical models against the Herschel-HIFI and -PACS observations, which were collected on December 30, 2010, and January 2, 2011, respectively.
Results: We demonstrate that Saturn's stratospheric water is not uniformly mixed as a function of latitude, but peaks at the equator and decreases poleward with a Gaussian distribution. We obtain our best fit with an equatorial mole fraction 1.1 ppb and a half width at half maximum of 25{\deg}, when accounting for a temperature increase in the two warm stratospheric vortices produced by Saturn's Great Storm of 2010-2011.
Conclusions: This work demonstrates that Enceladus is the main source of Saturn's stratospheric water. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. }}, doi = {10.1051/0004-6361/201935954}, adsurl = {}, adsnote = {Provided by the SAO/NASA Astrophysics Data System} }
  author = {{Cruikshank}, D.~P. and {Umurhan}, O.~M. and {Beyer}, R.~A. and 
	{Schmitt}, B. and {Keane}, J.~T. and {Runyon}, K.~D. and {Atri}, D. and 
	{White}, O.~L. and {Matsuyama}, I. and {Moore}, J.~M. and {McKinnon}, W.~B. and 
	{Sandford}, S.~A. and {Singer}, K.~N. and {Grundy}, W.~M. and 
	{Dalle Ore}, C.~M. and {Cook}, J.~C. and {Bertrand}, T. and 
	{Stern}, S.~A. and {Olkin}, C.~B. and {Weaver}, H.~A. and {Young}, L.~A. and 
	{Spencer}, J.~R. and {Lisse}, C.~M. and {Binzel}, R.~P. and 
	{Earle}, A.~M. and {Robbins}, S.~J. and {Gladstone}, G.~R. and 
	{Cartwright}, R.~J. and {Ennico}, K.},
  title = {{Recent cryovolcanism in Virgil Fossae on Pluto}},
  journal = {\icarus},
  keywords = {Pluto, Surface, Ices, IR spectroscopy, Interiors, Organic chemistry, Volcanism},
  year = 2019,
  volume = 330,
  pages = {155-168},
  abstract = {{The Virgil Fossae region on Pluto exhibits three spatially coincident
properties that are suggestive of recent cryovolcanic activity over an
area approximately 300 by 200 km. Situated in the fossae troughs or
channels and in the surrounding terrain are exposures of H$_{2}$O
ice in which there is entrained opaque red-colored matter of unknown
composition. The H$_{2}$O ice is also seen to carry spectral
signatures at 1.65 and 2.2 {$\mu$}m of NH$_{3}$ in some form,
possibly as a hydrate, an ammoniated salt, or some other compound. Model
calculations of NH$_{3}$ destruction in H$_{2}$O ice by
galactic cosmic rays suggest that the maximum lifetime of NH$_{3}$
in the uppermost meter of the exposed surface is  10$^{9}$ years,
while considerations of Lyman-{$\alpha$} ultraviolet and solar wind charged
particles suggest shorter timescales by a factor of 10 or 10000. Thus,
10$^{9}$ y is taken as an upper limit to the age of the
emplacement event, and it could be substantially younger.

The red colorant in the ammoniated H$_{2}$O in Virgil Fossae and
surroundings may be a macromolecular organic material (tholin) thought
to give color to much of Pluto's surface, but probably different in
composition and age. Owing to the limited spectral range of the New
Horizons imaging spectrometer and the signal precision of the data,
apart from the H$_{2}$O and NH$_{3}$ signatures there are no
direct spectroscopic clues to the chemistry of the strongly colored
deposit on Pluto. We suggest that the colored material was a component
of the fluid reservoir from which the material now on the surface in
this region was erupted. Although other compositions are possible, if it
is indeed a complex organic material it may incorporate organics
inherited from the solar nebula, further processed in a warm aqueous
environment inside Pluto.

A planet-scale stress pattern in Pluto's lithosphere induced by true
polar wander, freezing of a putative interior ocean, and surface loading
has caused fracturing in a broad arc west of Sputnik Planitia,
consistent with the structure of Virgil Fossae and similar extensional
features. This faulting may have facilitated the ascent of fluid in
subsurface reservoirs to reach the surface as flows and as fountains of
cryoclastic materials, consistent with the appearance of colored,
ammoniated H$_{2}$O ice deposits in and around Virgil Fossae.
Models of a cryoflow emerging from sources in Virgil Fossae indicate
that the lateral extent of the flow can be several km (Umurhan et al.,
2019). The deposit over the full length ($\gt$200 km) of the main trough
in the Virgil Fossae complex and extending through the north rim of
Elliot crater and varying in elevation over a range of  2.5 km, suggests
that it debouched from multiple sources, probably along the length of
the strike direction of the normal faults defining the graben. The
source or sources of the ammoniated H$_{2}$O are one or more
subsurface reservoirs that may or may not connect to the global ocean
postulated for Pluto's interior. Alternatives to cryovolcanism in
producing the observed characteristics of the region around Virgil
Fossae are explored in the discussion section of the paper.
  doi = {10.1016/j.icarus.2019.04.023},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Bertrand}, T. and {Forget}, F. and {Umurhan}, O.~M. and {Moore}, J.~M. and 
	{Young}, L.~A. and {Protopapa}, S. and {Grundy}, W.~M. and {Schmitt}, B. and 
	{Dhingra}, R.~D. and {Binzel}, R.~P. and {Earle}, A.~M. and 
	{Cruikshank}, D.~P. and {Stern}, S.~A. and {Weaver}, H.~A. and 
	{Ennico}, K. and {Olkin}, C.~B. and {New Horizons Science Team}
  title = {{The CH$_{4}$ cycles on Pluto over seasonal and astronomical timescales}},
  journal = {\icarus},
  archiveprefix = {arXiv},
  eprint = {1903.02096},
  primaryclass = {astro-ph.EP},
  keywords = {Pluto, CH$_{4}$, Paleoclimate, Modeling, GCM, Glacier, Volatile transport},
  year = 2019,
  volume = 329,
  pages = {148-165},
  abstract = {{Pluto's surface is covered in numerous CH$_{4}$ ice deposits, that
vary in texture and brightness, as revealed by the New Horizons
spacecraft as it flew by Pluto in July 2015. These observations suggest
that CH$_{4}$ on Pluto has a complex history, involving reservoirs
of different composition, thickness and stability controlled by volatile
processes occurring on different timescales. In order to interpret these
observations, we use a Pluto volatile transport model able to simulate
the cycles of N$_{2}$ and CH$_{4}$ ices over millions of
years. By assuming fixed solid mixing ratios, we explore how changes in
surface albedos, emissivities and thermal inertias impact volatile
transport. This work is therefore a direct and natural continuation of
the work by Bertrand et al. (2018), which only explored the
N$_{2}$ cycles. Results show that bright CH$_{4}$ deposits
can create cold traps for N$_{2}$ ice outside Sputnik Planitia,
leading to a strong coupling between the N$_{2}$ and
CH$_{4}$ cycles. Depending on the assumed albedo for
CH$_{4}$ ice, the model predicts CH$_{4}$ ice accumulation
(1) at the same equatorial latitudes where the Bladed Terrain Deposits
are observed, supporting the idea that these CH$_{4}$-rich
deposits are massive and perennial, or (2) at mid-latitudes (25{\deg}-
70{\deg}), forming a thick mantle which is consistent with New Horizons
observations. In our simulations, both CH$_{4}$ ice reservoirs are
not in an equilibrium state and either one can dominate the other over
long timescales, depending on the assumptions made for the
CH$_{4}$ albedo. This suggests that long-term volatile transport
exists between the observed reservoirs. The model also reproduces the
formation of N$_{2}$ deposits at mid-latitudes and in the
equatorial depressions surrounding the Bladed Terrain Deposits, as
observed by New Horizons. At the poles, only seasonal CH$_{4}$ and
N$_{2}$ deposits are obtained in Pluto's current orbital
configuration. Finally, we show that Pluto's atmosphere always
contained, over the last astronomical cycles, enough gaseous
CH$_{4}$ to absorb most of the incoming Lyman-{$\alpha$} flux.
  doi = {10.1016/j.icarus.2019.02.007},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Scarica}, P. and {Garate-Lopez}, I. and {Lebonnois}, S. and 
	{Piccioni}, G. and {Grassi}, D. and {Migliorini}, A. and {Tellmann}, S.
  title = {{Validation of the IPSL Venus GCM Thermal Structure with Venus Express Data}},
  journal = {Atmosphere},
  year = 2019,
  volume = 10,
  pages = {584},
  doi = {10.3390/atmos10100584},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Lee}, Y.~J. and {Jessup}, K.-L. and {Perez-Hoyos}, S. and {Titov}, D.~V. and 
	{Lebonnois}, S. and {Peralta}, J. and {Horinouchi}, T. and {Imamura}, T. and 
	{Limaye}, S. and {Marcq}, E. and {Takagi}, M. and {Yamazaki}, A. and 
	{Yamada}, M. and {Watanabe}, S. and {Murakami}, S.-y. and {Ogohara}, K. and 
	{McClintock}, W.~M. and {Holsclaw}, G. and {Roman}, A.},
  title = {{Long-term Variations of Venus{\rsquo}s 365 nm Albedo Observed by Venus Express, Akatsuki, MESSENGER, and the Hubble Space Telescope}},
  journal = {\aj},
  archiveprefix = {arXiv},
  eprint = {1907.09683},
  primaryclass = {astro-ph.EP},
  keywords = {planets and satellites: atmospheres, planets and satellites: individual: Venus, planets and satellites: terrestrial planets },
  year = 2019,
  volume = 158,
  eid = {126},
  pages = {126},
  abstract = {{An unknown absorber near the cloud-top level of Venus generates a broad
absorption feature from the ultraviolet (UV) to visible, peaking around
360 nm, and therefore plays a critical role in the solar energy
absorption. We present a quantitative study of the variability of the
cloud albedo at 365 nm and its impact on Venus{\rsquo}s solar heating
rates based on an analysis of Venus Express and Akatsuki UV images and
Hubble Space Telescope and MESSENGER UV spectral data; in this analysis,
the calibration correction factor of the UV images of Venus Express
(Venus Monitoring Camera) is updated relative to the Hubble and
MESSENGER albedo measurements. Our results indicate that the 365 nm
albedo varied by a factor of 2 from 2006 to 2017 over the entire planet,
producing a 25\%{\ndash}40\% change in the low-latitude solar heating rate
according to our radiative transfer calculations. Thus, the cloud-top
level atmosphere should have experienced considerable solar heating
variations over this period. Our global circulation model calculations
show that this variable solar heating rate may explain the observed
variations of zonal wind from 2006 to 2017. Overlaps in the timescale of
the long-term UV albedo and the solar activity variations make it
plausible that solar extreme UV intensity and cosmic-ray variations
influenced the observed albedo trends. The albedo variations might also
be linked with temporal variations of the upper cloud SO$_{2}$ gas
abundance, which affects the
H$_{2}$SO$_{4}${\ndash}H$_{2}$O aerosol formation.
  doi = {10.3847/1538-3881/ab3120},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Cordier}, D. and {Bonhommeau}, D.~A. and {Port}, S. and {Chevrier}, V. and 
	{Lebonnois}, S. and {Garc{\'{\i}}a-S{\'a}nchez}, F.},
  title = {{The Physical Origin of the Venus Low Atmosphere Chemical Gradient}},
  journal = {\apj},
  archiveprefix = {arXiv},
  eprint = {1908.07781},
  primaryclass = {astro-ph.EP},
  keywords = {planets and satellites: atmospheres, planets and satellites: individual: Venus, planets and satellites: surfaces, planets and satellites: tectonics },
  year = 2019,
  volume = 880,
  eid = {82},
  pages = {82},
  abstract = {{Venus shares many similarities with the Earth, but concomitantly, some
of its features are extremely original. This is especially true for its
atmosphere, where high pressures and temperatures are found at the
ground level. In these conditions, carbon dioxide, the main component of
Venus{\rsquo} atmosphere, is a supercritical fluid. The analysis of
VeGa-2 probe data has revealed the high instability of the region
located in the last few kilometers above the ground level. Recent works
have suggested an explanation based on the existence of a vertical
gradient of molecular nitrogen abundances, around 5 ppm per meter. Our
goal was then to identify which physical processes could lead to the
establishment of this intriguing nitrogen gradient, in the deep
atmosphere of Venus. Using an appropriate equation of state for the
binary mixture CO$_{2}${\ndash}N$_{2}$ under supercritical
conditions, and also molecular dynamics simulations, we have
investigated the separation processes of N$_{2}$ and
CO$_{2}$ in the Venusian context. Our results show that molecular
diffusion is strongly inefficient, and potential phase separation is an
unlikely mechanism. We have compared the quantity of CO$_{2}$
required to form the proposed gradient with what could be released by a
diffuse degassing from a low volcanic activity. The needed fluxes of
CO$_{2}$ are not so different from what can be measured over some
terrestrial volcanic systems, suggesting a similar effect at work on
  doi = {10.3847/1538-4357/ab27bd},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Turbet}, M. and {Ehrenreich}, D. and {Lovis}, C. and {Bolmont}, E. and 
	{Fauchez}, T.},
  title = {{The runaway greenhouse radius inflation effect. An observational diagnostic to probe water on Earth-sized planets and test the habitable zone concept}},
  journal = {\aap},
  archiveprefix = {arXiv},
  eprint = {1906.03527},
  primaryclass = {astro-ph.EP},
  keywords = {planets and satellites: atmospheres, planets and satellites: terrestrial planets, methods: numerical, telescopes, planets and satellites: physical evolution, atmospheric effects},
  year = 2019,
  volume = 628,
  eid = {A12},
  pages = {A12},
  abstract = {{Planets similar to Earth but slightly more irradiated are expected to
enter into a runaway greenhouse state, where all surface water rapidly
evaporates, forming an optically thick H$_{2}$O-dominated
atmosphere. For Earth, this extreme climate transition is thought to
occur for an increase of only  6\% in solar luminosity, though the exact
limit at which the transition would occur is still a highly debated
topic. In general, the runaway greenhouse is believed to be a
fundamental process in the evolution of Earth-sized, temperate planets.
Using 1D radiative-convective climate calculations accounting for thick,
hot water vapor-dominated atmospheres, we evaluate the transit
atmospheric thickness of a post-runaway greenhouse atmosphere, and find
that it could possibly reach over a thousand kilometers (i.e., a few
tens of percent of the Earth's radius). This abrupt radius inflation
resulting from the runaway-greenhouse-induced transition could be
detected statistically by ongoing and upcoming space missions. These
include satellites such as TESS, CHEOPS, and PLATO combined with precise
radial velocity mass measurements using ground-based spectrographs such
as ESPRESSO, CARMENES, or SPIRou. This radius inflation could also be
detected in multiplanetary systems such as TRAPPIST-1 once masses and
radii are known with good enough precision. This result provides the
community with an observational test of two points. The first point is
the concept of runaway greenhouse, which defines the inner edge of the
traditional habitable zone, and the exact limit of the runaway
greenhouse transition. In particular, this could provide an empirical
measurement of the irradiation at which Earth analogs transition from a
temperate to a runaway greenhouse climate state. This astronomical
measurement would make it possible to statistically estimate how close
Earth is from the runaway greenhouse. Second, it could be used as a test
for the presence (and statistical abundance) of water in temperate,
Earth-sized exoplanets.
  doi = {10.1051/0004-6361/201935585},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Encrenaz}, T. and {Greathouse}, T.~K. and {Aoki}, S. and {Daerden}, F. and 
	{Giuranna}, M. and {Forget}, F. and {Lefèvre}, F. and {Montmessin}, F. and 
	{Fouchet}, T. and {Bézard}, B. and {Atreya}, S.~K. and {DeWitt}, C. and 
	{Richter}, M.~J. and {Neary}, L. and {Viscardy}, S.},
  title = {{Ground-based infrared mapping of H$_{2}$O$_{2}$ on Mars near opposition}},
  journal = {\aap},
  keywords = {planets and satellites: composition, planets and satellites: terrestrial planets, infrared: planetary systems, infrared: general},
  year = 2019,
  volume = 627,
  eid = {A60},
  pages = {A60},
  abstract = {{We pursued our ground-based seasonal monitoring of hydrogen peroxide on
Mars using thermal imaging spectroscopy, with two observations of the
planet near opposition, in May 2016 (solar longitude Ls = 148.5{\deg},
diameter = 17 arcsec) and July 2018 (Ls = 209{\deg}, diameter = 23
arcsec). Data were recorded in the 1232-1242 cm$^{-1}$ range (8.1
{$\mu$}m) with the Texas Echelon Cross Echelle Spectrograph (TEXES) mounted
at the 3 m Infrared Telescope Facility (IRTF) at the Mauna Kea
Observatories. As in the case of our previous analyses, maps of
H$_{2}$O$_{2}$ were obtained using line depth ratios of weak
transitions of H$_{2}$O$_{2}$ divided by a weak
CO$_{2}$ line. The H$_{2}$O$_{2}$ map of April 2016
shows a strong dichotomy between the northern and southern hemispheres,
with a mean volume mixing ratio of 45 ppbv on the north side and less
than 10 ppbv on the south side; this dichotomy was expected by the
photochemical models developed in the LMD Mars Global Climate Model
(LMD-MGCM) and with the recently developed Global Environmental
Multiscale (GEM) model. The second measurement (July 2018) was taken in
the middle of the MY 34 global dust storm. H$_{2}$O$_{2}$
was not detected with a disk-integrated 2{$\sigma$} upper limit of 10 ppbv,
while both the LMD-MGCM and the LEM models predicted a value above 20
ppbv (also observed by TEXES in 2003) in the absence of dust storm. This
depletion is probably the result of the high dust content in the
atmosphere at the time of our observations, which led to a decrease in
the water vapor column density, as observed by the PFS during the global
dust storm. GCM simulations using the GEM model show that the
H$_{2}$O depletion leads to a drop in H$_{2}$O$_{2}$,
due to the lack of HO$_{2}$ radicals. Our result brings a new
constraint on the photochemistry of H$_{2}$O$_{2}$ in the
presence of a high dust content. In parallel, we reprocessed the whole
TEXES dataset of H$_{2}$O$_{2}$ measurements using the
latest version of the GEISA database (GEISA 2015). We recently found
that there is a significant difference in the H$_{2}$O$_{2}$
line strengths between the 2003 and 2015 versions of GEISA. Therefore,
all H$_{2}$O$_{2}$ volume mixing ratios up to 2014 from
TEXES measurements must be reduced by a factor of 1.75. As a
consequence, in four cases (Ls around 80{\deg}, 100{\deg}, 150{\deg}, and
209{\deg}) the H$_{2}$O$_{2}$ abundances show contradictory
values between different Martian years. At Ls = 209{\deg} the cause seems
to be the increased dust content associated with the global dust storm.
The inter-annual variability in the three other cases remains
unexplained at this time.
  doi = {10.1051/0004-6361/201935300},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Tran}, H. and {Turbet}, M. and {Hanoufa}, S. and {Landsheere}, X. and 
	{Chelin}, P. and {Ma}, Q. and {Hartmann}, J.-M.},
  title = {{The CO$_{2}$-broadened H$_{2}$O continuum in the 100-1500 cm$^{-1}$ region: Measurements, predictions and empirical model}},
  journal = {Journal of Quantitative Spectroscopy and Radiative Transfer},
  archiveprefix = {arXiv},
  eprint = {1903.08972},
  primaryclass = {astro-ph.EP},
  keywords = {CO$_{2}$-broadened H$_{2}$O continuum, CO$_{2}$, Line wings, CO$_{2}$-rich atmospheres, Line-shape correction factors},
  year = 2019,
  volume = 230,
  pages = {75-80},
  abstract = {{Transmission spectra of H$_{2}$O+CO$_{2}$ mixtures have been
recorded, at 296, 325 and 366 K, for various pressures and mixture
compositions using two experimental setups. Their analysis enables to
retrieve values of the ``continuum'' absorption by the
CO$_{2}$-broadened H$_{2}$O line wings between 100 and 1500
cm$^{-1}$. The results are in good agreement with those, around
1300 cm$^{-1}$, of the single previous experimental study
available. Comparisons are also made with direct predictions based on
line-shape correction factors {$\chi$} calculated, almost thirty years ago,
using a quasistatic approach and an input H$_{2}$Osbnd
CO$_{2}$ intermolecular potential. They show that this model quite
nicely predicts, with slightly overestimated values, the continuum over
a spectral range where it varies by more than three orders of magnitude.
An empirical correction is proposed, based on the experimental data,
which should be useful for radiative transfer and climate studies in
CO$_{2}$ rich planetary atmospheres.
  doi = {10.1016/j.jqsrt.2019.03.016},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Lillis}, R.~J. and {Fillingim}, M.~O. and {Ma}, Y. and {Gonzalez-Galindo}, F. and 
	{Forget}, F. and {Johnson}, C.~L. and {Mittelholz}, A. and {Russell}, C.~T. and 
	{Andersson}, L. and {Fowler}, C.~M.},
  title = {{Modeling Wind-Driven Ionospheric Dynamo Currents at Mars: Expectations for InSight Magnetic Field Measurements}},
  journal = {\grl},
  keywords = {Mars, ionosphere, dynamo, current, Insight, Magnetic},
  year = 2019,
  volume = 46,
  pages = {5083-5091},
  abstract = {{We model expected dynamo currents above, and resulting magnetic field
profiles at, InSight's landing site on Mars, including for the first
time the effect of electron-ion collisions. We calculate their diurnal
and seasonal variability using inputs from global models of the Martian
thermosphere, ionosphere, and magnetosphere. Modeled currents primarily
depend on plasma densities and the strength of the neutral wind
component perpendicular to the combined crustal and draped magnetic
fields that thread the ionosphere. Negligible at night, currents are the
strongest in the late morning and near solstices due to stronger winds
and near perihelion due to both stronger winds and higher plasma
densities from solar EUV photoionization. Resulting surface magnetic
fields of tens of nanotesla and occasionally $\gt$100 nT may be expected
at the InSight landing site. We expect currents and surface fields to
vary significantly with changes in the draped magnetic field caused by
Mars' dynamic solar wind environment.
  doi = {10.1029/2019GL082536},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Meza}, E. and {Sicardy}, B. and {Assafin}, M. and {Ortiz}, J.~L. and 
	{Bertrand}, T. and {Lellouch}, E. and {Desmars}, J. and {Forget}, F. and 
	{Bérard}, D. and {Doressoundiram}, A. and {Lecacheux}, J. and 
	{Marques Oliveira}, J. and {Roques}, F. and {Widemann}, T. and 
	{Colas}, F. and {Vachier}, F. and {Renner}, S. and {Leiva}, R. and 
	{Braga-Ribas}, F. and {Benedetti-Rossi}, G. and {Camargo}, J.~I.~B. and 
	{Dias-Oliveira}, A. and {Morgado}, B. and {Gomes-J{\'u}nior}, A.~R. and 
	{Vieira-Martins}, R. and {Behrend}, R. and {Tirado}, A.~C. and 
	{Duffard}, R. and {Morales}, N. and {Santos-Sanz}, P. and {Jel{\'{\i}}nek}, M. and 
	{Cunniffe}, R. and {Querel}, R. and {Harnisch}, M. and {Jansen}, R. and 
	{Pennell}, A. and {Todd}, S. and {Ivanov}, V.~D. and {Opitom}, C. and 
	{Gillon}, M. and {Jehin}, E. and {Manfroid}, J. and {Pollock}, J. and 
	{Reichart}, D.~E. and {Haislip}, J.~B. and {Ivarsen}, K.~M. and 
	{LaCluyze}, A.~P. and {Maury}, A. and {Gil-Hutton}, R. and {Dhillon}, V. and 
	{Littlefair}, S. and {Marsh}, T. and {Veillet}, C. and {Bath}, K.-L. and 
	{Beisker}, W. and {Bode}, H.-J. and {Kretlow}, M. and {Herald}, D. and 
	{Gault}, D. and {Kerr}, S. and {Pavlov}, H. and {Farag{\'o}}, O. and 
	{Kl{\"o}s}, O. and {Frappa}, E. and {Lavayssière}, M. and 
	{Cole}, A.~A. and {Giles}, A.~B. and {Greenhill}, J.~G. and 
	{Hill}, K.~M. and {Buie}, M.~W. and {Olkin}, C.~B. and {Young}, E.~F. and 
	{Young}, L.~A. and {Wasserman}, L.~H. and {Devogèle}, M. and 
	{French}, R.~G. and {Bianco}, F.~B. and {Marchis}, F. and {Brosch}, N. and 
	{Kaspi}, S. and {Polishook}, D. and {Manulis}, I. and {Ait Moulay Larbi}, M. and 
	{Benkhaldoun}, Z. and {Daassou}, A. and {El Azhari}, Y. and 
	{Moulane}, Y. and {Broughton}, J. and {Milner}, J. and {Dobosz}, T. and 
	{Bolt}, G. and {Lade}, B. and {Gilmore}, A. and {Kilmartin}, P. and 
	{Allen}, W.~H. and {Graham}, P.~B. and {Loader}, B. and {McKay}, G. and 
	{Talbot}, J. and {Parker}, S. and {Abe}, L. and {Bendjoya}, P. and 
	{Rivet}, J.-P. and {Vernet}, D. and {Di Fabrizio}, L. and {Lorenzi}, V. and 
	{Magazz{\'u}}, A. and {Molinari}, E. and {Gazeas}, K. and {Tzouganatos}, L. and 
	{Carbognani}, A. and {Bonnoli}, G. and {Marchini}, A. and {Leto}, G. and 
	{Sanchez}, R.~Z. and {Mancini}, L. and {Kattentidt}, B. and 
	{Dohrmann}, M. and {Guhl}, K. and {Rothe}, W. and {Walzel}, K. and 
	{Wortmann}, G. and {Eberle}, A. and {Hampf}, D. and {Ohlert}, J. and 
	{Krannich}, G. and {Murawsky}, G. and {G{\"a}hrken}, B. and 
	{Gloistein}, D. and {Alonso}, S. and {Rom{\'a}n}, A. and {Communal}, J.-E. and 
	{Jabet}, F. and {deVisscher}, S. and {Sérot}, J. and {Janik}, T. and 
	{Moravec}, Z. and {Machado}, P. and {Selva}, A. and {Perell{\'o}}, C. and 
	{Rovira}, J. and {Conti}, M. and {Papini}, R. and {Salvaggio}, F. and 
	{Noschese}, A. and {Tsamis}, V. and {Tigani}, K. and {Barroy}, P. and 
	{Irzyk}, M. and {Neel}, D. and {Godard}, J.~P. and {Lanoiselée}, D. and 
	{Sogorb}, P. and {Vérilhac}, D. and {Bretton}, M. and {Signoret}, F. and 
	{Ciabattari}, F. and {Naves}, R. and {Boutet}, M. and {De Queiroz}, J. and 
	{Lindner}, P. and {Lindner}, K. and {Enskonatus}, P. and {Dangl}, G. and 
	{Tordai}, T. and {Eichler}, H. and {Hattenbach}, J. and {Peterson}, C. and 
	{Molnar}, L.~A. and {Howell}, R.~R.},
  title = {{Lower atmosphere and pressure evolution on Pluto from ground-based stellar occultations, 1988-2016}},
  journal = {\aap},
  archiveprefix = {arXiv},
  eprint = {1903.02315},
  primaryclass = {astro-ph.EP},
  keywords = {methods: observational, methods: data analysis, planets and satellites: atmospheres, techniques: photometric, planets and satellites: physical evolution, planets and satellites: terrestrial planets},
  year = 2019,
  volume = 625,
  eid = {A42},
  pages = {A42},
  abstract = {{Context. The tenuous nitrogen (N$_{2}$) atmosphere on Pluto
undergoes strong seasonal effects due to high obliquity and orbital
eccentricity, and has recently (July 2015) been observed by the New
Horizons spacecraft. 
Aims: The main goals of this study are (i) to construct a well calibrated record of the seasonal evolution of surface pressure on Pluto and (ii) to constrain the structure of the lower atmosphere using a central flash observed in 2015.
Methods: Eleven stellar occultations by Pluto observed between 2002 and 2016 are used to retrieve atmospheric profiles (density, pressure, temperature) between altitude levels of 5 and 380 km (i.e. pressures from 10 {$\mu$}bar to 10 nbar).
Results: (i) Pressure has suffered a monotonic increase from 1988 to 2016, that is compared to a seasonal volatile transport model, from which tight constraints on a combination of albedo and emissivity of N$_{2}$ ice are derived. (ii) A central flash observed on 2015 June 29 is consistent with New Horizons REX profiles, provided that (a) large diurnal temperature variations (not expected by current models) occur over Sputnik Planitia; and/or (b) hazes with tangential optical depth of 0.3 are present at 4-7 km altitude levels; and/or (c) the nominal REX density values are overestimated by an implausibly large factor of 20\%; and/or (d) higher terrains block part of the flash in the Charon facing hemisphere. }}, doi = {10.1051/0004-6361/201834281}, adsurl = {}, adsnote = {Provided by the SAO/NASA Astrophysics Data System} }
  author = {{Vandaele}, A.~C. and {Korablev}, O. and {Daerden}, F. and {Aoki}, S. and 
	{Thomas}, I.~R. and {Altieri}, F. and {L{\'o}pez-Valverde}, M. and 
	{Villanueva}, G. and {Liuzzi}, G. and {Smith}, M.~D. and {Erwin}, J.~T. and 
	{Trompet}, L. and {Fedorova}, A.~A. and {Montmessin}, F. and 
	{Trokhimovskiy}, A. and {Belyaev}, D.~A. and {Ignatiev}, N.~I. and 
	{Luginin}, M. and {Olsen}, K.~S. and {Baggio}, L. and {Alday}, J. and 
	{Bertaux}, J.-L. and {Betsis}, D. and {Bolsée}, D. and {Clancy}, R.~T. and 
	{Cloutis}, E. and {Depiesse}, C. and {Funke}, B. and {Garcia-Comas}, M. and 
	{Gérard}, J.-C. and {Giuranna}, M. and {Gonzalez-Galindo}, F. and 
	{Grigoriev}, A.~V. and {Ivanov}, Y.~S. and {Kaminski}, J. and 
	{Karatekin}, O. and {Lefèvre}, F. and {Lewis}, S. and {L{\'o}pez-Puertas}, M. and 
	{Mahieux}, A. and {Maslov}, I. and {Mason}, J. and {Mumma}, M.~J. and 
	{Neary}, L. and {Neefs}, E. and {Patrakeev}, A. and {Patsaev}, D. and 
	{Ristic}, B. and {Robert}, S. and {Schmidt}, F. and {Shakun}, A. and 
	{Teanby}, N.~A. and {Viscardy}, S. and {Willame}, Y. and {Whiteway}, J. and 
	{Wilquet}, V. and {Wolff}, M.~J. and {Bellucci}, G. and {Patel}, M.~R. and 
	{L{\'o}pez-Moreno}, J.-J. and {Forget}, F. and {Wilson}, C.~F. and 
	{Svedhem}, H. and {Vago}, J.~L. and {Rodionov}, D. and {NOMAD Science Team} and 
	{Vandaele}, A.~C. and {L{\'o}pez-Moreno}, J.-J. and {Bellucci}, G. and 
	{Patel}, M.~R. and {Alonso-Rodrigo}, G. and {Aoki}, S. and {Altieri}, F. and 
	{Bauduin}, S. and {Bolsée}, D. and {Carrozzo}, G. and {Clancy}, R.~T. and 
	{Cloutis}, E. and {Crismani}, M. and {Daerden}, F. and {da Pieve}, F. and 
	{D'Aversa}, E. and {Depiesse}, C. and {Erwin}, J.~T. and {Etiope}, G. and 
	{Fedorova}, A.~A. and {Funke}, B. and {Fussen}, D. and {Garcia-Comas}, M. and 
	{Geminale}, A. and {Gérard}, J.-C. and {Giuranna}, M. and 
	{Gkouvelis}, L. and {Gonzalez-Galindo}, F. and {Holmes}, J. and 
	{Hubert}, B. and {Ignatiev}, N.~I. and {Kaminski}, J. and {Karatekin}, O. and 
	{Kasaba}, Y. and {Kass}, D. and {Kleinb{\"o}hl}, A. and {Lanciano}, O. and 
	{Lefèvre}, F. and {Lewis}, S. and {Liuzzi}, G. and {L{\'o}pez-Puertas}, M. and 
	{L{\'o}pez-Valverde}, M. and {Mahieux}, A. and {Mason}, J. and 
	{Mumma}, M.~J. and {Nakagawa}, H. and {Neary}, L. and {Neefs}, E. and 
	{Novak}, R.~E. and {Oliva}, F. and {Piccialli}, A. and {Renotte}, E. and 
	{Ritter}, B. and {Robert}, S. and {Schmidt}, F. and {Schneider}, N. and 
	{Sindoni}, G. and {Smith}, M.~D. and {Teanby}, N.~A. and {Thiemann}, E. and 
	{Thomas}, I.~R. and {Trokhimovskiy}, A. and {Trompet}, L. and 
	{Vander Auwera}, J. and {Villanueva}, G. and {Viscardy}, S. and 
	{Whiteway}, J. and {Wilquet}, V. and {Willame}, Y. and {Wolff}, M.~J. and 
	{Wolkenberg}, P. and {Yelle}, R. and {ACS Science Team} and 
	{Alday}, J. and {Altieri}, F. and {Anufreychik}, K. and {Arnold}, G. and 
	{Baggio}, L. and {Belyaev}, D.~A. and {Bertaux}, J.-L. and {Duxbury}, N. and 
	{Fedorova}, A.~A. and {Forget}, F. and {Fouchet}, T. and {Grassi}, D. and 
	{Grigoriev}, A.~V. and {Guerlet}, S. and {Hartogh}, P. and {Ignatiev}, N.~I. and 
	{Kasaba}, Y. and {Khatuntsev}, I. and {Kokonkov}, N. and {Korablev}, O. and 
	{Krasnopolsky}, V. and {Kuzmin}, R. and {Lacombe}, G. and {Lefèvre}, F. and 
	{Lellouch}, E. and {L{\'o}pez-Valverde}, M. and {Maslov}, I. and 
	{Luginin}, M. and {M{\"a}{\"a}tt{\"a}nen}, A. and {Marcq}, E. and 
	{Martin-Torres}, J. and {Medvedev}, A. and {Millour}, E. and 
	{Montmessin}, F. and {Moshkin}, B. and {Olsen}, K.~S. and {Patel}, M.~R. and 
	{Patrakeev}, A. and {Patsaev}, D. and {Quantin-Nataf}, C. and 
	{Rodionov}, D. and {Rodin}, A. and {Shakun}, A. and {Shematovich}, V. and 
	{Thomas}, I.~R. and {Thomas}, N. and {Trokhimovsky}, A. and 
	{Vazquez}, L. and {Vincendon}, M. and {Wilquet}, V. and {Wilson}, C.~F. and 
	{Young}, R. and {Zasova}, L. and {Zelenyi}, L. and {Zorzano}, M.~P.
  title = {{Martian dust storm impact on atmospheric H$_{2}$O and D/H observed by ExoMars Trace Gas Orbiter}},
  journal = {\nat},
  year = 2019,
  volume = 568,
  pages = {521-525},
  abstract = {{Global dust storms on Mars are rare$^{1,2}$ but can affect the
atmospheric dynamics and inflation of the atmosphere$^{3}$,
primarily owing to solar heating of the dust$^{3}$. In turn,
changes in atmospheric dynamics can affect the distribution of
atmospheric water vapour, with potential implications for the
atmospheric photochemistry and climate on Mars$^{4}$. Recent
observations of the water vapour abundance in the Martian atmosphere
during dust storm conditions revealed a high-altitude increase in
atmospheric water vapour that was more pronounced at high northern
latitudes$^{5,6}$, as well as a decrease in the water column at
low latitudes$^{7,8}$. Here we present concurrent, high-resolution
measurements of dust, water and semiheavy water (HDO) at the onset of a
global dust storm, obtained by the NOMAD and ACS instruments onboard the
ExoMars Trace Gas Orbiter. We report the vertical distribution of the
HDO/H$_{2}$O ratio (D/H) from the planetary boundary layer up to
an altitude of 80 kilometres. Our findings suggest that before the onset
of the dust storm, HDO abundances were reduced to levels below
detectability at altitudes above 40 kilometres. This decrease in HDO
coincided with the presence of water-ice clouds. During the storm, an
increase in the abundance of H$_{2}$O and HDO was observed at
altitudes between 40 and 80 kilometres. We propose that these increased
abundances may be the result of warmer temperatures during the dust
storm causing stronger atmospheric circulation and preventing ice cloud
formation, which may confine water vapour to lower altitudes through
gravitational fall and subsequent sublimation of ice
crystals$^{3}$. The observed changes in H$_{2}$O and HDO
abundance occurred within a few days during the development of the dust
storm, suggesting a fast impact of dust storms on the Martian
  doi = {10.1038/s41586-019-1097-3},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Korablev}, O. and {Avandaele}, A.~C. and {Montmessin}, F. and 
	{Fedorova}, A.~A. and {Trokhimovskiy}, A. and {Forget}, F. and 
	{Lefèvre}, F. and {Daerden}, F. and {Thomas}, I.~R. and 
	{Trompet}, L. and {Erwin}, J.~T. and {Aoki}, S. and {Robert}, S. and 
	{Neary}, L. and {Viscardy}, S. and {Grigoriev}, A.~V. and {Ignatiev}, N.~I. and 
	{Shakun}, A. and {Patrakeev}, A. and {Belyaev}, D.~A. and {Bertaux}, J.-L. and 
	{Olsen}, K.~S. and {Baggio}, L. and {Alday}, J. and {Ivanov}, Y.~S. and 
	{Ristic}, B. and {Mason}, J. and {Willame}, Y. and {Depiesse}, C. and 
	{Hetey}, L. and {Berkenbosch}, S. and {Clairquin}, R. and {Queirolo}, C. and 
	{Beeckman}, B. and {Neefs}, E. and {Patel}, M.~R. and {Bellucci}, G. and 
	{L{\'o}pez-Moreno}, J.-J. and {Wilson}, C.~F. and {Etiope}, G. and 
	{Zelenyi}, L. and {Svedhem}, H. and {Vago}, J.~L. and {ACS Science Team} and 
	{NOMAD Science Team} and {Alonso-Rodrigo}, G. and {Altieri}, F. and 
	{Anufreychik}, K. and {Arnold}, G. and {Bauduin}, S. and {Bolsée}, D. and 
	{Carrozzo}, G. and {Clancy}, R.~T. and {Cloutis}, E. and {Crismani}, M. and 
	{da Pieve}, F. and {D'Aversa}, E. and {Duxbury}, N. and {Encrenaz}, T. and 
	{Fouchet}, T. and {Funke}, B. and {Fussen}, D. and {Garcia-Comas}, M. and 
	{Gérard}, J.-C. and {Giuranna}, M. and {Gkouvelis}, L. and 
	{Gonzalez-Galindo}, F. and {Grassi}, D. and {Guerlet}, S. and 
	{Hartogh}, P. and {Holmes}, J. and {Hubert}, B. and {Kaminski}, J. and 
	{Karatekin}, O. and {Kasaba}, Y. and {Kass}, D. and {Khatuntsev}, I. and 
	{Kleinb{\"o}hl}, A. and {Kokonkov}, N. and {Krasnopolsky}, V. and 
	{Kuzmin}, R. and {Lacombe}, G. and {Lanciano}, O. and {Lellouch}, E. and 
	{Lewis}, S. and {Luginin}, M. and {Liuzzi}, G. and {L{\'o}pez-Puertas}, M. and 
	{L{\'o}pez-Valverde}, M. and {M{\"a}{\"a}tt{\"a}nen}, A. and 
	{Mahieux}, A. and {Marcq}, E. and {Martin-Torres}, J. and {Maslov}, I. and 
	{Medvedev}, A. and {Millour}, E. and {Moshkin}, B. and {Mumma}, M.~J. and 
	{Nakagawa}, H. and {Novak}, R.~E. and {Oliva}, F. and {Patsaev}, D. and 
	{Piccialli}, A. and {Quantin-Nataf}, C. and {Renotte}, E. and 
	{Ritter}, B. and {Rodin}, A. and {Schmidt}, F. and {Schneider}, N. and 
	{Shematovich}, V. and {Smith}, M.~D. and {Teanby}, N.~A. and 
	{Thiemann}, E. and {Thomas}, N. and {Vander Auwera}, J. and 
	{Vazquez}, L. and {Villanueva}, G. and {Vincendon}, M. and {Whiteway}, J. and 
	{Wilquet}, V. and {Wolff}, M.~J. and {Wolkenberg}, P. and {Yelle}, R. and 
	{Young}, R. and {Zasova}, L. and {Zorzano}, M.~P.},
  title = {{No detection of methane on Mars from early ExoMars Trace Gas Orbiter observations}},
  journal = {\nat},
  year = 2019,
  volume = 568,
  pages = {517-520},
  abstract = {{The detection of methane on Mars has been interpreted as indicating that
geochemical or biotic activities could persist on Mars
today$^{1}$. A number of different measurements of methane show
evidence of transient, locally elevated methane concentrations and
seasonal variations in background methane concentrations$^{2-5}$.
These measurements, however, are difficult to reconcile with our current
understanding of the chemistry and physics of the Martian
atmosphere$^{6,7}$, which{\mdash}given methane's lifetime of
several centuries{\mdash}predicts an even, well mixed distribution of
methane$^{1,6,8}$. Here we report highly sensitive measurements of
the atmosphere of Mars in an attempt to detect methane, using the ACS
and NOMAD instruments onboard the ESA-Roscosmos ExoMars Trace Gas
Orbiter from April to August 2018. We did not detect any methane over a
range of latitudes in both hemispheres, obtaining an upper limit for
methane of about 0.05 parts per billion by volume, which is 10 to 100
times lower than previously reported positive detections$^{2,4}$.
We suggest that reconciliation between the present findings and the
background methane concentrations found in the Gale crater$^{4}$
would require an unknown process that can rapidly remove or sequester
methane from the lower atmosphere before it spreads globally.
  doi = {10.1038/s41586-019-1096-4},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Yang}, J. and {Leconte}, J. and {Wolf}, E.~T. and {Merlis}, T. and 
	{Koll}, D.~D.~B. and {Forget}, F. and {Abbot}, D.~S.},
  title = {{Simulations of Water Vapor and Clouds on Rapidly Rotating and Tidally Locked Planets: A 3D Model Intercomparison}},
  journal = {\apj},
  keywords = {astrobiology, methods: numerical, planets and satellites: atmospheres, planets and satellites: general, radiative transfer },
  year = 2019,
  volume = 875,
  eid = {46},
  pages = {46},
  abstract = {{Robustly modeling the inner edge of the habitable zone is essential for
determining the most promising potentially habitable exoplanets for
atmospheric characterization. Global climate models (GCMs) have become
the standard tool for calculating this boundary, but divergent results
have emerged among the various GCMs. In this study, we perform an
intercomparison of standard GCMs used in the field on a rapidly rotating
planet receiving a G-star spectral energy distribution and on a tidally
locked planet receiving an M-star spectral energy distribution.
Experiments both with and without clouds are examined. We find
relatively small difference (within 8 K) in global-mean surface
temperature simulation among the models in the G-star case with clouds.
In contrast, the global-mean surface temperature simulation in the
M-star case is highly divergent (20{\ndash}30 K). Moreover, even
differences in the simulated surface temperature when clouds are turned
off are significant. These differences are caused by differences in
cloud simulation and/or radiative transfer, as well as complex
interactions between atmospheric dynamics and these two processes. For
example we find that an increase in atmospheric absorption of shortwave
radiation can lead to higher relative humidity at high altitudes
globally and, therefore, a significant decrease in planetary radiation
emitted to space. This study emphasizes the importance of basing
conclusions about planetary climate on simulations from a variety of
GCMs and motivates the eventual comparison of GCM results with
terrestrial exoplanet observations to improve their performance.
  doi = {10.3847/1538-4357/ab09f1},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Turbet}, M. and {Tran}, H. and {Pirali}, O. and {Forget}, F. and 
	{Boulet}, C. and {Hartmann}, J.-M.},
  title = {{Far infrared measurements of absorptions by CH$_{4}$ + CO$_{2}$ and H$_{2}$ + CO$_{2}$ mixtures and implications for greenhouse warming on early Mars}},
  journal = {\icarus},
  archiveprefix = {arXiv},
  eprint = {1805.02595},
  primaryclass = {astro-ph.EP},
  keywords = {Mars, Spectroscopy, Measurement, Methane, Hydrogen, Collision induced absorptions, Climate},
  year = 2019,
  volume = 321,
  pages = {189-199},
  abstract = {{We present an experimental study of the absorption, between 40 and 640
cm$^{-1}$, by CO$_{2}$, CH$_{4}$ and H$_{2}$
gases as well as by H$_{2}$ + CO$_{2}$ and CH$_{4}$ +
CO$_{2}$ mixtures at room temperature. A Fourier transform
spectrometer associated to a multi-pass cell, whose optics were adjusted
to obtain a 152 m path length, were used to record transmission spectra
at total pressures up to about 0.98 bar. These measurements provide
information concerning the collision-induced absorption (CIA) bands as
well as about the wing of the CO$_{2}$ 15 {$\mu$}m band. Our results
for the CIAs of pure gases are, within uncertainties, in agreement with
previous determinations, validating our experimental and data analysis
procedures. We then consider the CIAs by H$_{2}$ + CO$_{2}$
and CH$_{4}$ + CO$_{2}$ and the low frequency wing of the
pure CO$_{2}$ 15 {$\mu$}m band, for which there are, to our
knowledge, no previous measurements. We confirm experimentally the
theoretical prediction of Wordsworth et al. (2017) that the
H$_{2}$ + CO$_{2}$ and CH$_{4}$ + CO$_{2}$ CIAs
are significantly stronger in the 50-550 cm$^{-1}$ region than
those of H$_{2}$ + N$_{2}$ and CH$_{4}$ +
N$_{2}$, respectively. However, we find that the shape and the
strength of these recorded CIAs differ from the aforementioned
predictions. For the pure CO$_{2}$ line-wings, we show that both
the {$\chi$}-factor deduced from measurements near 4 {$\mu$}m and a
line-mixing model very well describe the observed strongly
sub-Lorentzian behavior in the 500-600 cm$^{-1}$ region. These
experimental results open renewed perspectives for studies of the past
climate of Mars and extrasolar analogues.
  doi = {10.1016/j.icarus.2018.11.021},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Encrenaz}, T. and {Greathouse}, T.~K. and {Marcq}, E. and {Sagawa}, H. and 
	{Widemann}, T. and {Bézard}, B. and {Fouchet}, T. and {Lefèvre}, F. and 
	{Lebonnois}, S. and {Atreya}, S.~K. and {Lee}, Y.~J. and {Giles}, R. and 
	{Watanabe}, S.},
  title = {{HDO and SO$_{2}$ thermal mapping on Venus. IV. Statistical analysis of the SO$_{2}$ plumes}},
  journal = {\aap},
  keywords = {planets and satellites: atmospheres, planets and satellites: terrestrial planets, infrared: planetary systems},
  year = 2019,
  volume = 623,
  eid = {A70},
  pages = {A70},
  abstract = {{Since January 2012 we have been monitoring the behavior of sulfur
dioxide and water on Venus, using the Texas Echelon Cross-Echelle
Spectrograph (TEXES) imaging spectrometer at the NASA InfraRed Telescope
Facility (IRTF, Mauna Kea Observatory). We present here the observations
obtained between January 2016 and September 2018. As in the case of our
previous runs, data were recorded around 1345 cm$^{-1}$ (7.4
{$\mu$}m). The molecules SO$_{2}$, CO$_{2}$, and HDO (used as a
proxy for H$_{2}$O) were observed, and the cloudtop of Venus was
probed at an altitude of about 64 km. The volume mixing ratio of
SO$_{2}$ was estimated using the SO$_{2}$/CO$_{2}$
line depth ratios of weak transitions; the H$_{2}$O volume mixing
ratio was derived from the HDO/CO$_{2}$ line depth ratio, assuming
a D/H ratio of 200 times the Vienna Standard Mean Ocean Water (VSMOW).
As reported in our previous analyses, the SO$_{2}$ mixing ratio
shows strong variations with time and also over the disk, showing
evidence of the formation of SO$_{2}$ plumes with a lifetime of a
few hours; in contrast, the H$_{2}$O abundance is remarkably
uniform over the disk and shows moderate variations as a function of
time. We performed a statistical analysis of the behavior of the
SO$_{2}$ plumes, using all TEXES data between 2012 and 2018. They
appear mostly located around the equator. Their distribution as a
function of local time seems to show a depletion around noon; we do not
have enough data to confirm this feature definitely. The distribution of
SO$_{2}$ plumes as a function of longitude shows no clear feature,
apart from a possible depletion around 100E-150E and around 300E-360E.
There seems to be a tendency for the H$_{2}$O volume mixing ratio
to decrease after 2016, and for the SO$_{2}$ mixing ratio to
increase after 2014. However, we see no clear anti-correlation between
the SO$_{2}$ and H$_{2}$O abundances at the cloudtop,
neither on the individual maps nor over the long term. Finally, there is
a good agreement between the TEXES results and those obtained in the UV
range (SPICAV/Venus Express and UVI/Akatsuki) at a slightly higher
altitude. This agreement shows that SO$_{2}$ observations obtained
in the thermal infrared can be used to extend the local time coverage of
the SO$_{2}$ measurements obtained in the UV range.
  doi = {10.1051/0004-6361/201833511},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Nishikawa}, Y. and {Lognonné}, P. and {Kawamura}, T. and 
	{Spiga}, A. and {Stutzmann}, E. and {Schimmel}, M. and {Bertrand}, T. and 
	{Forget}, F. and {Kurita}, K.},
  title = {{Mars' Background Free Oscillations}},
  journal = {\ssr},
  keywords = {Mars, Planetary free oscillation, GCM, Seismometer, Normal mode, InSight},
  year = 2019,
  volume = 215,
  eid = {13},
  pages = {13},
  abstract = {{Observations and inversion of the eigenfrequencies of free oscillations
constitute powerful tools to investigate the internal structure of a
planet. On Mars, such free oscillations can be excited by atmospheric
pressure and wind stresses from the Martian atmosphere, analogous to
what occurs on Earth. Over long periods and on a global scale, this
phenomenon may continuously excite Mars' background free oscillations
(MBFs), which constitute the so-called Martian hum. However, the source
exciting MBFs is related both to the global-scale atmospheric
circulation on Mars and to the variations in pressure and wind at the
planetary boundary layer, for which no data are available.

To overcome this drawback, we focus herein on a global-scale source and
use results of simulations based on General Circular Models (GCMs). GCMs
can predict and reproduce long-term, global-scale Martian pressure and
wind variations and suggest that, contrary to what happens on Earth,
daily correlations in the Martian hum might be generated by the
solar-driven GCM. After recalling the excitation terms, we calculate
MBFs by using GCM computations and estimate the contribution to the hum
made by the global atmospheric circulation. Although we work at the
lower limit of MBF signals, the results indicate that the signal is
likely to be periodic, which would allow us to use more efficient
stacking theories than can be applied to Earth's hum. We conclude by
discussing the perspectives for the InSight SEIS instrument to detect
the Martian hum. The amplitude of the MBF signal is on the order of
nanogals and is therefore hidden by instrumental and thermal noise,
which implies that, provided the predicted daily coherence in hum
excitation is present, the InSight SEIS seismometer should be capable of
  doi = {10.1007/s11214-019-0579-9},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Ferri}, F. and {Karatekin}, {\"O}. and {Lewis}, S.~R. and {Forget}, F. and 
	{Aboudan}, A. and {Colombatti}, G. and {Bettanini}, C. and {Debei}, S. and 
	{Van Hove}, B. and {Dehant}, V. and {Harri}, A.-M. and {Leese}, M. and 
	{M{\"a}kinen}, T. and {Millour}, E. and {Muller-Wodarg}, I. and 
	{Ori}, G.~G. and {Pacifici}, A. and {Paris}, S. and {Patel}, M. and 
	{Schoenenberger}, M. and {Herath}, J. and {Siili}, T. and {Spiga}, A. and 
	{Tokano}, T. and {Towner}, M. and {Withers}, P. and {Asmar}, S. and 
	{Plettemeier}, D.},
  title = {{ExoMars Atmospheric Mars Entry and Landing Investigations and Analysis (AMELIA)}},
  journal = {\ssr},
  keywords = {Mars, Entry Descent and Landing (EDL), Dynamical models, Trajectory, Attitude, Atmospheric investigations},
  year = 2019,
  volume = 215,
  eid = {8},
  pages = {8},
  abstract = {{The entry, descent and landing of Schiaparelli, the ExoMars Entry,
descent and landing Demonstrator Module (EDM), offered a rare
(once-per-mission) opportunity for in situ investigations of the martian
environment over a wide altitude range. The aim of the ExoMars AMELIA
experiment was to exploit the Entry, Descent and Landing System (EDLS)
engineering measurements for scientific investigations of Mars'
atmosphere and surface. Here we present the simulations, modelling and
the planned investigations prior to the Entry, Descent and Landing (EDL)
event that took place on 19th October 2016. Despite the unfortunate
conclusion of the Schiaparelli mission, flight data recorded during the
entry and the descent until the loss of signal, have been recovered.
These flight data, although limited and affected by transmission
interruptions and malfunctions, are essential for investigating the
anomaly and validating the EDL operation, but can also contribute
towards the partial achievement of AMELIA science objectives.
  doi = {10.1007/s11214-019-0578-x},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{White}, O.~L. and {Moore}, J.~M. and {Howard}, A.~D. and {McKinnon}, W.~B. and 
	{Keane}, J.~T. and {Singer}, K.~N. and {Bertrand}, T. and {Robbins}, S.~J. and 
	{Schenk}, P.~M. and {Schmitt}, B. and {Buratti}, B.~J. and {Stern}, S.~A. and 
	{Ennico}, K. and {Olkin}, C.~B. and {Weaver}, H.~A. and {Young}, L.~A. and 
	{New Horizons Geology}, G. and {Imaging Theme Team}},
  title = {{Washboard and fluted terrains on Pluto as evidence for ancient glaciation}},
  journal = {Nature Astronomy},
  year = 2019,
  volume = 3,
  pages = {62-68},
  abstract = {{Distinctive landscapes termed `washboard' and `fluted'
terrains$^{1,2}$, which border the N$_{2}$ ice plains of
Sputnik Planitia along its northwest margin, are among the most
enigmatic landforms yet seen on Pluto. These terrains consist of
parallel to sub-parallel ridges that display a remarkably consistent
east-northeast-west-southwest orientation{\mdash}a configuration that
does not readily point to a simple analogous terrestrial or planetary
process or landform. Here, we report on mapping and analysis of their
morphometry and distribution as a means to determine their origin. Based
on their occurrence in generally low-elevation, low-relief settings
adjacent to Sputnik Planitia that coincide with a major tectonic system,
and through comparison with fields of sublimation pits seen in southern
Sputnik Planitia, we conclude that washboard and fluted terrains
represent crustal debris that were buoyant in pitted glacial
N$_{2}$ ice that formerly covered this area, and which were
deposited after the N$_{2}$ ice receded via sublimation. Crater
surface age estimates indicate that this N$_{2}$ ice glaciation
formed and disappeared early in Pluto's history, soon after formation of
the Sputnik Planitia basin. These terrains constitute an entirely new
category of glacial landform.
  doi = {10.1038/s41550-018-0592-z},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Ordonez-Etxeberria}, I. and {Hueso}, R. and {S{\'a}nchez-Lavega}, A. and 
	{Millour}, E. and {Forget}, F.},
  title = {{Meteorological pressure at Gale crater from a comparison of REMS/MSL data and MCD modelling: Effect of dust storms}},
  journal = {\icarus},
  keywords = {Mars, atmosphere, Mars, climate, Atmospheres, dynamics, Dust storms},
  year = 2019,
  volume = 317,
  pages = {591-609},
  abstract = {{We examine the record of atmospheric pressure in Gale crater measured
in-situ by the Rover Environmental Monitoring Station (REMS) instrument
(G{\'o}mez-Elvira et al., 2012) on the Mars Science Laboratory (MSL)
rover over two Martian years. We compare the data with pressure
predictions from the Mars Climate Database (MCD) (Forget et al., 1999;
Millour et al., 2015) version 5.2, which is a climatological database
derived from numerical simulations of the Martian atmosphere produced by
a General Circulation Model run over several Martian years. Seasonal and
daily trends in pressure data from REMS are well reproduced by the
standard climatology of the MCD using its high resolution mode. This
high-resolution mode extrapolates pressure values from the nominal model
into the altitude of each location using a high-resolution topography
model and a fine tuning of the vertical scale height that was chosen to
mimic effects of slope winds not directly accounted for in the General
Circulation Model on which the MCD is based. Differences between the
synthetic MCD pressure data and the REMS measurements are produced by
meteorological features that are identified on particular groups of sols
and quantified in intensity. We show that regional dust storms outside
Gale crater and dust abundance at the crater are important factors in
the behaviour of the pressure exciting larger amplitudes on the daily
pressure variations and causing most of the largest REMS-MCD
differences. We compare the pressure signals with published data of the
dust optical depth obtained by the REMS ultraviolet photodiodes and the
Mastcam instrument on MSL, and with orbital images of the planet
acquired by the MARCI instrument on the Mars Reconnaissance Orbiter
(MRO). We show that in some cases regional dust storms induce a
characteristic signature in the surface pressure measured by REMS
several sols before the dust arrives to Gale crater. We explore the
capability of daily pressure measurements to serve as a fast detector of
the development of dust storms in the context of the MSL, Insight and
Mars 2020 missions.
  doi = {10.1016/j.icarus.2018.09.003},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Pluriel}, W. and {Marcq}, E. and {Turbet}, M.},
  title = {{Modeling the albedo of Earth-like magma ocean planets with H$_{2}$O-CO$_{2}$ atmospheres}},
  journal = {\icarus},
  archiveprefix = {arXiv},
  eprint = {1809.02036},
  primaryclass = {astro-ph.EP},
  keywords = {Atmospheres, Albedo, Spectroscopy, Radiative transfer, Modeling},
  year = 2019,
  volume = 317,
  pages = {583-590},
  abstract = {{During accretion, the young rocky planets are so hot that they become
endowed with a magma ocean. From that moment, the mantle convective
thermal flux control the cooling of the planet and an atmosphere is
created by outgassing. This atmosphere will then play a key role during
this cooling phase. Studying this cooling phase in details is a
necessary step to explain the great diversity of the observed telluric
planets and especially to assess the presence of surface liquid water.
We used here a radiative-convective 1D atmospheric model
(H$_{2}$O, CO$_{2}$) to study the impact of the Bond albedo
on the evolution of magma ocean planets. We derived from this model the
thermal emission spectrum and the spectral reflectance of these planets,
from which we calculated their Bond albedos. Compared to Marcq et al.
(2017), the model now includes a new module to compute the Rayleigh
scattering, and state of the art CO$_{2}$ and H$_{2}$O
gaseous opacities data in the visible and infrared spectral ranges. We
show that the Bond albedo of these planets depends on their surface
temperature and results from a competition between Rayleigh scattering
from the gases and Mie scattering from the clouds. The colder the
surface temperature is, the thicker the clouds are, and the higher the
Bond albedo is. We also evidence that the relative abundances of
CO$_{2}$ and H$_{2}$O in the atmosphere strongly impact the
Bond albedo. The Bond albedo is higher for atmospheres dominated by the
CO$_{2}$, better Rayleigh scatterer than H$_{2}$O. Finally,
we provide the community with an empirical formula for the Bond albedo
that could be useful for future studies of magma ocean planets.
  doi = {10.1016/j.icarus.2018.08.023},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}