@comment{{This file has been generated by bib2bib 1.94}}
@comment{{Command line: /usr/bin/bib2bib --quiet -c 'not journal:"Discussions"' -c 'title:"Venus" or title:"venusian"' -c $type="ARTICLE" -oc pubvenus0.txt -ob pubvenus0.bib}}
  author = {{Lebonnois}, S. and {Schubert}, G. and {Forget}, F. and {Spiga}, A.
  title = {{Planetary boundary layer and slope winds on Venus}},
  journal = {\icarus},
  keywords = {Venus, Atmosphere, Planetary boundary layer, Slope winds},
  year = 2018,
  volume = 314,
  pages = {149-158},
  abstract = {{Few constraints are available to characterize the deep atmosphere of
Venus, though this region is crucial to understand the interactions
between surface and atmosphere on Venus. Based on simulations performed
with the IPSL Venus Global Climate Model, the possible structure and
characteristics of Venus' planetary boundary layer (PBL) are
investigated. The vertical profile of the potential temperature in the
deepest 10 km above the surface and its diurnal variations are
controlled by radiative and dynamical processes. The model predicts a
diurnal cycle for the PBL activity, with a stable nocturnal PBL while
convective activity develops during daytime. The diurnal convective PBL
is strongly correlated with surface solar flux and is maximum around
noon and in low latitude regions. It typically reaches less than 2 km
above the surface, but its vertical extension is much higher over high
elevations, and more precisely over the western flanks of elevated
terrains. This correlation is explained by the impact of surface winds,
which undergo a diurnal cycle with downward katabatic winds at night and
upward anabatic winds during the day along the slopes of high-elevation
terrains. The convergence of these daytime anabatic winds induces upward
vertical winds, that are responsible for the correlation between height
of the convective boundary layer and topography.
  doi = {10.1016/j.icarus.2018.06.006},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Garate-Lopez}, I. and {Lebonnois}, S.},
  title = {{Latitudinal variation of clouds' structure responsible for Venus' cold collar}},
  journal = {\icarus},
  keywords = {Venus atmosphere, Cold collar, Modelling},
  year = 2018,
  volume = 314,
  pages = {1-11},
  abstract = {{Global Climate Models (GCM) are very useful tools to study theoretically
the general dynamics and specific phenomena in planetary atmospheres. In
the case of Venus, several GCMs succeeded in reproducing the
atmosphere's superrotation and the global temperature field. However,
the highly variable polar temperature and the permanent cold collar
present at 60$^{o}$ -80$^{o}$ latitude have not been
reproduced satisfactorily yet.

Here we improve the radiative transfer scheme of the Institut Pierre
Simon Laplace Venus GCM in order to numerically simulate the polar
thermal features in Venus atmosphere. The main difference with the
previous model is that we now take into account the latitudinal
variation of the cloud structure. Both solar heating rates and infrared
cooling rates have been modified to consider the cloud top's altitude
decrease toward the poles and the variation in latitude of the different
particle modes' abundances.

A new structure that closely resembles the observed cold collar appears
in the average temperature field at 2 {\times}10$^{4}$ - 4
{\times}10$^{3}$  Pa ({\sim} 62 - 66  km) altitude range and
60$^{o}$ -90$^{o}$ latitude band. It is not isolated
from the pole as in the observation-based maps, but the obtained
temperature values (220 K) are in good agreement with observed values.
Temperature polar maps across this region show an inner warm region
where the polar vortex is observed, but the obtained 230 K average value
is colder than the observed mean value and the simulated horizontal
structure does not show the fine-scale features present within the

The comparison with a simulation that does not take into account the
latitudinal variation of the cloud structure in the infrared cooling
computation, shows that the cloud structure is essential in the cold
collar formation. Although our analysis focuses on the improvement of
the radiative forcing and the variations it causes in the thermal
structure, polar dynamics is definitely affected by this modified
environment and a noteworthy upwelling motion is found in the cold
collar area.
  doi = {10.1016/j.icarus.2018.05.011},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Navarro}, T. and {Schubert}, G. and {Lebonnois}, S.},
  title = {{Atmospheric mountain wave generation on Venus and its influence on the solid planet's rotation rate}},
  journal = {Nature Geoscience},
  year = 2018,
  volume = 11,
  pages = {487-491},
  abstract = {{The Akatsuki spacecraft observed a 10,000-km-long meridional structure
at the top of the cloud deck of Venus that appeared stationary with
respect to the surface and was interpreted as a gravity wave.
Additionally, over four Venus solar days of observations, other such
waves were observed to appear in the afternoon over equatorial highland
regions. This indicates a direct influence of the solid planet on the
whole Venusian atmosphere despite dissimilar rotation rates of 243 and 4
days, respectively. How such gravity waves might be generated on Venus
is not understood. Here, we use general circulation model simulations of
the Venusian atmosphere to show that the observations are consistent
with stationary gravity waves over topographic highs{\mdash}or mountain
waves{\mdash}that are generated in the afternoon in equatorial regions by
the diurnal cycle of near-surface atmospheric stability. We find that
these mountain waves substantially contribute to the total atmospheric
torque that acts on the planet's surface. We estimate that mountain
waves, along with the thermal tide and baroclinic waves, can produce a
change in the rotation rate of the solid body of about 2 minutes per
solar day. This interplay between the solid planet and atmosphere may
explain some of the difference in rotation rates (equivalent to a change
in the length of day of about 7 minutes) measured by spacecraft over the
past 40 years.
  doi = {10.1038/s41561-018-0157-x},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Read}, P.~L. and {Lebonnois}, S.},
  title = {{Superrotation on Venus, on Titan, and Elsewhere}},
  journal = {Annual Review of Earth and Planetary Sciences},
  year = 2018,
  volume = 46,
  pages = {175-202},
  abstract = {{The superrotation of the atmospheres of Venus and Titan has puzzled
dynamicists for many years and seems to put these planets in a very
different dynamical regime from most other planets. In this review, we
consider how to define superrotation objectively and explore the
constraints that determine its occurrence. Atmospheric superrotation
also occurs elsewhere in the Solar System and beyond, and we compare
Venus and Titan with Earth and other planets for which wind estimates
are available. The extreme superrotation on Venus and Titan poses some
difficult challenges for numerical models of atmospheric circulation,
much more difficult than for more rapidly rotating planets such as Earth
or Mars. We consider mechanisms for generating and maintaining a
superrotating state, all of which involve a global meridional
overturning circulation. The role of nonaxisymmetric eddies is crucial,
however, but the detailed mechanisms may differ between Venus, Titan,
and other planets.
  doi = {10.1146/annurev-earth-082517-010137},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{S{\'a}nchez-Lavega}, A. and {Lebonnois}, S. and {Imamura}, T. and 
	{Read}, P. and {Luz}, D.},
  title = {{The Atmospheric Dynamics of Venus}},
  journal = {\ssr},
  keywords = {Venus, Atmospheric dynamics},
  year = 2017,
  volume = 212,
  pages = {1541-1616},
  abstract = {{We review our current knowledge of the atmospheric dynamics of Venus
prior to the Akatsuki mission, in the altitude range from the surface to
approximately the cloud tops located at about 100 km altitude. The
three-dimensional structure of the wind field in this region has been
determined with a variety of techniques over a broad range of spatial
and temporal scales (from the mesoscale to planetary, from days to
years, in daytime and nighttime), spanning a period of about 50 years
(from the 1960s to the present). The global panorama is that the mean
atmospheric motions are essentially zonal, dominated by the so-called
super-rotation (an atmospheric rotation that is 60 to 80 times faster
than that of the planetary body). The zonal winds blow westward (in the
same direction as the planet rotation) with a nearly constant speed of
{\tilde} 100 m s\^{}$\{$-1$\}$ at the cloud tops (65-70 km altitude) from latitude
50{\deg}N to 50{\deg}S, then decreasing their speeds monotonically from
these latitudes toward the poles. Vertically, the zonal winds decrease
with decreasing altitude towards velocities {\tilde} 1-3 m s\^{}$\{$-1$\}$ in a
layer of thickness {\tilde} 10 km close to the surface. Meridional
motions with peak speeds of {\tilde} 15 m s\^{}$\{$-1$\}$ occur within the upper
cloud at 65 km altitude and are related to a Hadley cell circulation and
to the solar thermal tide. Vertical motions with speeds {\tilde}1-3 m
s\^{}$\{$-1$\}$ occur in the statically unstable layer between altitudes of
{\tilde} 50 - 55 km. All these motions are permanent with speed
variations of the order of {\tilde}10\%. Various types of wave, from
mesoscale gravity waves to Rossby-Kelvin planetary scale waves, have
been detected at and above cloud heights, and are considered to be
candidates as agents for carrying momentum that drives the
super-rotation, although numerical models do not fully reproduce all the
observed features. Momentum transport by atmospheric waves and the solar
tide is thought to be an indispensable component of the general
circulation of the Venus atmosphere. Another conspicuous feature of the
atmospheric circulation is the presence of polar vortices. These are
present in both hemispheres and are regions of warmer and lower clouds,
seen prominently at infrared wavelengths, showing a highly variable
morphology and motions. The vortices spin with a period of 2-3 days. The
South polar vortex rotates around a geographical point which is itself
displaced from the true pole of rotation by {\tilde} 3 degrees. The polar
vortex is surrounded and constrained by the cold collar, an
infrared-dark region of lower temperatures. We still lack detailed
models of the mechanisms underlying the dynamics of these features and
how they couple (or not) to the super-rotation. The nature of the
super-rotation relates to the angular momentum stored in the atmosphere
and how it is transported between the tropics and higher latitudes, and
between the deep atmosphere and upper levels. The role of eddy processes
is crucial, but likely involves the complex interaction of a variety of
different types of eddy, either forced directly by radiative heating and
mechanical interactions with the surface or through various forms of
instability. Numerical models have achieved some significant recent
success in capturing some aspects of the observed super-rotation,
consistent with the scenario discussed by Gierasch (J. Atmos. Sci.
32:1038-1044, 1975) and Rossow and Williams (J. Atmos. Sci. 36:377-389,
1979), but many uncertainties remain, especially in the deep atmosphere.
The theoretical framework developed to explain the circulation in
Venus's atmosphere is reviewed, as well as the numerical models that
have been built to elucidate the super-rotation mechanism. These tools
are used to analyze the respective roles of the different waves in the
processes driving the observed motions. Their limitations and suggested
directions for improvements are discussed.
  doi = {10.1007/s11214-017-0389-x},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Limaye}, S.~S. and {Lebonnois}, S. and {Mahieux}, A. and {P{\"a}tzold}, M. and 
	{Bougher}, S. and {Bruinsma}, S. and {Chamberlain}, S. and {Clancy}, R.~T. and 
	{Gérard}, J.-C. and {Gilli}, G. and {Grassi}, D. and {Haus}, R. and 
	{Herrmann}, M. and {Imamura}, T. and {Kohler}, E. and {Krause}, P. and 
	{Migliorini}, A. and {Montmessin}, F. and {Pere}, C. and {Persson}, M. and 
	{Piccialli}, A. and {Rengel}, M. and {Rodin}, A. and {Sandor}, B. and 
	{Sornig}, M. and {Svedhem}, H. and {Tellmann}, S. and {Tanga}, P. and 
	{Vandaele}, A.~C. and {Widemann}, T. and {Wilson}, C.~F. and 
	{M{\"u}ller-Wodarg}, I. and {Zasova}, L.},
  title = {{The thermal structure of the Venus atmosphere: Intercomparison of Venus Express and ground based observations of vertical temperature and density profiles$^{✰}$}},
  journal = {\icarus},
  year = 2017,
  volume = 294,
  pages = {124-155},
  abstract = {{The Venus International Reference Atmosphere (VIRA) model contains
tabulated values of temperature and number densities obtained by the
experiments on the Venera entry probes, Pioneer Venus Orbiter and
multi-probe missions in the 1980s. The instruments on the recent Venus
Express orbiter mission generated a significant amount of new
observational data on the vertical and horizontal structure of the Venus
atmosphere from 40 km to about 180 km altitude from April 2006 to
November 2014. Many ground based experiments have provided data on the
upper atmosphere (90-130 km) temperature structure since the publication
of VIRA in 1985. The ``Thermal Structure of the Venus Atmosphere'' Team
was supported by the International Space Studies Institute (ISSI), Bern,
Switzerland, from 2013 to 2015 in order to combine and compare the
ground-based observations and the VEx observations of the thermal
structure as a first step towards generating an updated VIRA model.
Results of this comparison are presented in five latitude bins and three
local time bins by assuming hemispheric symmetry. The intercomparison of
the ground-based and VEx results provides for the first time a
consistent picture of the temperature and density structure in the 40
km-180 km altitude range. The Venus Express observations have
considerably increased our knowledge of the Venus atmospheric thermal
structure above {\sim}40 km and provided new information above 100 km.
There are, however, still observational gaps in latitude and local time
above certain regions. Considerable variability in the temperatures and
densities is seen above 100 km but certain features appear to be
systematically present, such as a succession of warm and cool layers.
Preliminary modeling studies support the existence of such layers in
agreement with a global scale circulation. The intercomparison focuses
on average profiles but some VEx experiments provide sufficient global
coverage to identify solar thermal tidal components.
  doi = {10.1016/j.icarus.2017.04.020},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Lebonnois}, S. and {Schubert}, G.},
  title = {{The deep atmosphere of Venus and the possible role of density-driven separation of CO$_{2}$ and N$_{2}$}},
  journal = {Nature Geoscience},
  year = 2017,
  volume = 10,
  pages = {473-477},
  abstract = {{With temperatures around 700 K and pressures of around 75 bar, the
deepest 12 km of the atmosphere of Venus are so hot and dense that the
atmosphere behaves like a supercritical fluid. The Soviet VeGa-2 probe
descended through the atmosphere in 1985 and obtained the only reliable
temperature profile for the deep Venusian atmosphere thus far. In this
temperature profile, the atmosphere appears to be highly unstable at
altitudes below 7 km, contrary to expectations. We argue that the VeGa-2
temperature profile could be explained by a change in the atmospheric
gas composition, and thus molecular mass, with depth. We propose that
the deep atmosphere consists of a non-homogeneous layer in which the
abundance of N$_{2}$--the second most abundant constituent of the
Venusian atmosphere after CO$_{2}$--gradually decreases to
near-zero at the surface. It is difficult to explain a decline in
N$_{2}$ towards the surface with known nitrogen sources and sinks
for Venus. Instead we suggest, partly based on experiments on
supercritical fluids, that density-driven separation of N$_{2}$
from CO$_{2}$ can occur under the high pressures of Venus's deep
atmosphere, possibly by molecular diffusion, or by natural
density-driven convection. If so, the amount of nitrogen in the
atmosphere of Venus is 15\% lower than commonly assumed. We suggest that
similar density-driven separation could occur in other massive planetary
  doi = {10.1038/ngeo2971},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Lefèvre}, M. and {Spiga}, A. and {Lebonnois}, S.},
  title = {{Three-dimensional turbulence-resolving modeling of the Venusian cloud layer and induced gravity waves}},
  journal = {Journal of Geophysical Research (Planets)},
  keywords = {3-D mesoscale modeling, Venus, convective cloud layer, gravity waves},
  year = 2017,
  volume = 122,
  pages = {134-149},
  abstract = {{The impact of the cloud convective layer of the atmosphere of Venus on
the global circulation remains unclear. The recent observations of
gravity waves at the top of the cloud by the Venus Express mission
provided some answers. These waves are not resolved at the scale of
global circulation models (GCM); therefore, we developed an
unprecedented 3-D turbulence-resolving large-eddy simulations (LES)
Venusian model using the Weather Research and Forecast terrestrial
model. The forcing consists of three different heating rates: two
radiative ones for solar and infrared and one associated with the
adiabatic cooling/warming of the global circulation. The rates are
extracted from the Laboratoire de Météorlogie Dynamique
Venus GCM using two different cloud models. Thus, we are able to
characterize the convection and associated gravity waves in function of
latitude and local time. To assess the impact of the global circulation
on the convective layer, we used rates from a 1-D radiative-convective
model. The resolved layer, taking place between 1.0 {\times}
10$^{5}$ and 3.8 {\times} 10$^{4}$ Pa (48-53 km), is
organized as polygonal closed cells of about 10 km wide with vertical
wind of several meters per second. The convection emits gravity waves
both above and below the convective layer leading to temperature
perturbations of several tenths of kelvin with vertical wavelength
between 1 and 3 km and horizontal wavelength from 1 to 10 km. The
thickness of the convective layer and the amplitudes of waves are
consistent with observations, though slightly underestimated. The global
dynamics heating greatly modify the convective layer.
  doi = {10.1002/2016JE005146},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Gilli}, G. and {Lebonnois}, S. and {Gonz{\'a}lez-Galindo}, F. and 
	{L{\'o}pez-Valverde}, M.~A. and {Stolzenbach}, A. and {Lefèvre}, F. and 
	{Chaufray}, J.~Y. and {Lott}, F.},
  title = {{Thermal structure of the upper atmosphere of Venus simulated by a ground-to-thermosphere GCM}},
  journal = {\icarus},
  year = 2017,
  volume = 281,
  pages = {55-72},
  abstract = {{We present here the thermal structure of the upper atmosphere of Venus
predicted by a full self-consistent Venus General Circulation Model
(VGCM) developed at Laboratoire de Météorologie Dynamique
(LMD) and extended up to the thermosphere of the planet. Physical and
photochemical processes relevant at those altitudes, plus a
non-orographic GW parameterisation, have been added. All those
improvements make the LMD-VGCM the only existing ground-to-thermosphere
3D model for Venus: a unique tool to investigate the atmosphere of Venus
and to support the exploration of the planet by remote sounding. The aim
of this paper is to present the model reference results, to describe the
role of radiative, photochemical and dynamical effects in the observed
thermal structure in the upper mesosphere/lower thermosphere of the
planet. The predicted thermal structure shows a succession of warm and
cold layers, as recently observed. A cooling trend with increasing
latitudes is found during daytime at all altitudes, while at nighttime
the trend is inverse above about 110  km, with an atmosphere up to 15 K
warmer towards the pole. The latitudinal variation is even smaller at
the terminator, in agreement with observations. Below about 110  km, a
nighttime warm layer whose intensity decreases with increasing latitudes
is predicted by our GCM. A comparison of model results with a selection
of recent measurements shows an overall good agreement in terms of
trends and order of magnitude. Significant data-model discrepancies may
be also discerned. Among them, thermospheric temperatures are about
40-50 K colder and up to 30 K warmer than measured at terminator and at
nighttime, respectively. The altitude layer of the predicted mesospheric
local maximum (between 100 and 120  km) is also higher than observed.
Possible interpretations are discussed and several sensitivity tests
performed to understand the data-model discrepancies and to propose
future model improvements.
  doi = {10.1016/j.icarus.2016.09.016},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Lebonnois}, S. and {Sugimoto}, N. and {Gilli}, G.},
  title = {{Wave analysis in the atmosphere of Venus below 100-km altitude, simulated by the LMD Venus GCM}},
  journal = {\icarus},
  keywords = {Venus, atmosphere, Atmospheres, dynamics, Numerical modeling},
  year = 2016,
  volume = 278,
  pages = {38-51},
  abstract = {{A new simulation of Venus atmospheric circulation obtained with the LMD
Venus GCM is described and the simulated wave activity is analyzed.
Agreement with observed features of the temperature structure, static
stability and zonal wind field is good, such as the presence of a cold
polar collar, diurnal and semi-diurnal tides. At the resolution used (96
longitudes {\times} 96 latitudes), a fully developed superrotation is
obtained both when the simulation is initialized from rest and from an
atmosphere already in superrotation, though winds are still weak below
the clouds (roughly half the observed values). The atmospheric waves
play a crucial role in the angular momentum budget of the Venus's
atmospheric circulation. In the upper cloud, the vertical angular
momentum is transported by the diurnal and semi-diurnal tides. Above the
cloud base (approximately 1 bar), equatorward transport of angular
momentum is done by polar barotropic and mid- to high-latitude
baroclinic waves present in the cloud region, with frequencies between 5
and 20 cycles per Venus day (periods between 6 and 23 Earth days). In
the middle cloud, just above the convective layer, a Kelvin type wave
(period around 7.3 Ed) is present at the equator, as well as a
low-latitude Rossby-gravity type wave (period around 16 Ed). Below the
clouds, large-scale mid- to high-latitude gravity waves develop and play
a significant role in the angular momentum balance.
  doi = {10.1016/j.icarus.2016.06.004},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Bertaux}, J.-L. and {Khatuntsev}, I.~V. and {Hauchecorne}, A. and 
	{Markiewicz}, W.~J. and {Marcq}, E. and {Lebonnois}, S. and 
	{Patsaeva}, M. and {Turin}, A. and {Fedorova}, A.},
  title = {{Influence of Venus topography on the zonal wind and UV albedo at cloud top level: The role of stationary gravity waves}},
  journal = {Journal of Geophysical Research (Planets)},
  keywords = {Venus, zonal wind, gravity waves, Venus Express, VMC, superrotation},
  year = 2016,
  volume = 121,
  pages = {1087-1101},
  abstract = {{Based on the analysis of UV images (at 365 nm) of Venus cloud top
(altitude 67 {\plusmn} 2 km) collected with Venus Monitoring Camera on
board Venus Express (VEX), it is found that the zonal wind speed south
of the equator (from 5{\deg}S to 15{\deg}S) shows a conspicuous variation
(from -101 to -83 m/s) with geographic longitude of Venus, correlated
with the underlying relief of Aphrodite Terra. We interpret this pattern
as the result of stationary gravity waves produced at ground level by
the uplift of air when the horizontal wind encounters a mountain slope.
These waves can propagate up to the cloud top level, break there, and
transfer their momentum to the zonal flow. Such upward propagation of
gravity waves and influence on the wind speed vertical profile was shown
to play an important role in the middle atmosphere of the Earth by
Lindzen (1981) but is not reproduced in the current GCM of Venus
atmosphere from LMD. (Laboratoire de Météorologie
Dynamique) In the equatorial regions, the UV albedo at 365 nm varies
also with longitude. We argue that this variation may be simply
explained by the divergence of the horizontal wind field. In the
longitude region (from 60{\deg} to -10{\deg}) where the horizontal wind
speed is increasing in magnitude (stretch), it triggers air upwelling
which brings the UV absorber at cloud top level and decreases the albedo
and vice versa when the wind is decreasing in magnitude (compression).
This picture is fully consistent with the classical view of Venus
meridional circulation, with upwelling at equator revealed by horizontal
air motions away from equator: the longitude effect is only an
additional but important modulation of this effect. This interpretation
is comforted by a recent map of cloud top H$_{2}$O, showing that
near the equator the lower UV albedo longitude region is correlated with
increased H$_{2}$O. We argue that H$_{2}$O enhancement is
the sign of upwelling, suggesting that the UV absorber is also brought
to cloud top by upwelling.
  doi = {10.1002/2015JE004958},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Lebonnois}, S. and {Eymet}, V. and {Lee}, C. and {Vatant d'Ollone}, J.
  title = {{Analysis of the radiative budget of the Venusian atmosphere based on infrared Net Exchange Rate formalism}},
  journal = {Journal of Geophysical Research (Planets)},
  keywords = {Venus atmosphere, radiative transfer, Net Exchange Rate analysis},
  year = 2015,
  volume = 120,
  pages = {1186-1200},
  abstract = {{A detailed one-dimensional analysis of the energy balance in Venus
atmosphere is proposed in this work, based on the Net Exchange Rate
formalism that allows the identification in each altitude region of the
dominant energy exchanges controlling the temperature. Well-known
parameters that control the temperature profile are the solar flux
deposition and the cloud particle distribution. Balance between solar
heating and infrared energy exchanges is analyzed for each region: upper
atmosphere (from cloud top to 100 km), upper cloud, middle cloud, cloud
base, and deep atmosphere (cloud base to surface). The energy
accumulated below the clouds is transferred to the cloud base through
infrared windows, mostly at 3-4 {$\mu$}m and 5-7 {$\mu$}m. The continuum
opacity in these spectral regions is not well known for the hot
temperatures and large pressures of Venus's deep atmosphere but strongly
affects the temperature profile from cloud base to surface. From cloud
base, upward transport of energy goes through convection and short-range
radiative exchanges up to the middle cloud where the atmosphere is thin
enough in the 20-30 {$\mu$}m window to cool directly to space. Total
opacity in this spectral window between the 15 {$\mu$}m CO$_{2}$ band
and the CO$_{2}$ collision-induced absorption has a strong impact
on the temperature in the cloud convective layer. Improving our
knowledge of the gas opacities in these different windows through new
laboratory measurements or ab initio computations, as well as improving
the constraints on cloud opacities would help to separate gas and cloud
contributions and secure a better understanding of Venus's atmosphere
energy balance.
  doi = {10.1002/2015JE004794},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Grassi}, D. and {Politi}, R. and {Ignatiev}, N.~I. and {Plainaki}, C. and 
	{Lebonnois}, S. and {Wolkenberg}, P. and {Montabone}, L. and 
	{Migliorini}, A. and {Piccioni}, G. and {Drossart}, P.},
  title = {{The Venus nighttime atmosphere as observed by the VIRTIS-M instrument. Average fields from the complete infrared data set}},
  journal = {Journal of Geophysical Research (Planets)},
  keywords = {Venus, Planetary atmospheres},
  year = 2014,
  volume = 119,
  pages = {837-849},
  abstract = {{We present and discuss here the average fields of the Venus atmosphere
derived from the nighttime observations in the 1960-2350 cm$^{-1}$
spectral range by the VIRTIS-M instrument on board the Venus Express
satellite. These fields include: (a) the air temperatures in the 1-100
mbar pressure range (\~{}85-65 km above the surface), (b) the altitude of
the clouds top, and (c) the average CO mixing ratio. A new retrieval
code based on the Bayesian formalism has been developed and validated on
simulated observations, to statistically assess the retrieval
capabilities of the scheme once applied to the VIRTIS data. The same
code has then been used to process the entire VIRTIS-M data set.
Resulting individual retrievals have been binned on the basis of local
time and latitude, to create average fields. Air temperature fields
confirm the general trends previously reported in Grassi et al. (2010),
using a simplified retrieval scheme and a more limited data set. At the
lowest altitudes probed by VIRTIS (\~{}65 km), air temperatures are
strongly asymmetric around midnight, with a pronounced minima at 3LT,
70{\deg}S. Moving to higher levels, the air temperatures first become
more uniform in local time (\~{}75 km), then display a colder region on the
evening side at the upper boundary of VIRTIS sensitivity range (\~{}80 km).
As already shown by Ignatiev et al. (2008) for the dayside, the cloud
effective altitude increases monotonically from the south pole to the
equator. However, the variations observed in night data are consistent
with an overall variation of just 1 km, much smaller than the 4 km
reported for the dayside. The cloud altitudes appear slightly higher on
the evening side. Both observations are consistent with a less vigorous
meridional circulation on the nightside of the planet. Carbon monoxide
is not strongly constrained by the VIRTIS-M data. However, average
fields present a clear maximum of 80 ppm around 60{\deg}S, well above the
retrieval uncertainty. Once the intrinsic low sensitivity of VIRTIS data
in the region of cold collar is kept in mind, this datum is consistent
with a [CO] enrichment toward the poles driven by meridional
  doi = {10.1002/2013JE004586},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Marcq}, E. and {Lebonnois}, S.},
  title = {{Simulations of the latitudinal variability of CO-like and OCS-like passive tracers below the clouds of Venus using the Laboratoire de Météorologie Dynamique GCM}},
  journal = {Journal of Geophysical Research (Planets)},
  keywords = {Venus, atmosphere, general circulation model, passive tracers, carbon monoxide, carbonyl sulfide},
  year = 2013,
  volume = 118,
  pages = {1983-1990},
  abstract = {{The lower atmosphere of Venus below the clouds is a transitional region
between the relatively calm lowermost scale height and the superrotating
atmosphere in the cloud region and above. Any observational constraint
is then welcome to help in the development of general circulation models
of Venus, a difficult task considering the thickness of its atmosphere.
Starting from a state-of-the-art 3-D Venus General Circulation Model
(GCM), we have included passive tracers in order to investigate the
latitudinal variability of two minor gaseous species, carbonyl sulfide
(OCS) and carbon monoxide (CO), whose vertical profiles and mixing
ratios are known to vary with latitude between 30 and 40km. The
relaxation to chemical equilibrium is crudely parametrized through a
vertically uniform time scale {$\tau$}. A satisfactory agreement with
available observations is obtained with
10$^{8}$s{\lsim}{$\tau$}$_{CO}${\lsim}5{\middot}10$^{8}$ s
and 10$^{7}$s{\lsim}{$\tau$}$_{OCS}${\lsim}10$^{8}$ s.
These results, in addition to validating the general circulation below
the clouds, are also helpful in characterizing the chemical kinetics of
Venus' atmosphere. This complements the much more sophisticated chemical
models which focus more on thermodynamical equilibrium.
  doi = {10.1002/jgre.20146},
  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 = {{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 = {{Cottereau}, L. and {Rambaux}, N. and {Lebonnois}, S. and {Souchay}, J.
  title = {{The various contributions in Venus rotation rate and LOD}},
  journal = {\aap},
  archiveprefix = {arXiv},
  eprint = {1104.4009},
  primaryclass = {astro-ph.EP},
  keywords = {celestial mechanics, planets and satellites: individual: Venus},
  year = 2011,
  volume = 531,
  eid = {A45},
  pages = {A45},
  abstract = {{Context. Thanks to the Venus Express Mission, new data on the properties
of Venus could be obtained, in particular concerning its rotation. 
Aims: In view of these upcoming results, the purpose of this paper is to determine and compare the major physical processes influencing the rotation of Venus and, more particularly, the angular rotation rate.
Methods: Applying models already used for Earth, the effect of the triaxiality of a rigid Venus on its period of rotation are computed. Then the variations of Venus rotation caused by the elasticity, the atmosphere, and the core of the planet are evaluated.
Results: Although the largest irregularities in the rotation rate of the Earth on short time scales are caused by its atmosphere and elastic deformations, we show that the irregularities for Venus are dominated by the tidal torque exerted by the Sun on its solid body. Indeed, as Venus has a slow rotation, these effects have a large amplitude of two minutes of time (mn). These variations in the rotation rate are greater than the one induced by atmospheric wind variations that can reach 25-50 s of time (s), depending on the simulation used. The variations due to the core effects that vary with its size between 3 and 20 s are smaller. Compared to these effects, the influence of the elastic deformation caused by the zonal tidal potential is negligible.
Conclusions: As the variations in the rotation of Venus reported here are close to 3 mn peak to peak, they should influence past, present, and future observations, thereby providing further constraints on the planet's internal structure and atmosphere. }}, doi = {10.1051/0004-6361/201116606}, adsurl = {}, adsnote = {Provided by the SAO/NASA Astrophysics Data System} }
  author = {{Parish}, H.~F. and {Schubert}, G. and {Covey}, C. and {Walterscheid}, R.~L. and 
	{Grossman}, A. and {Lebonnois}, S.},
  title = {{Decadal variations in a Venus general circulation model}},
  journal = {\icarus},
  year = 2011,
  volume = 212,
  pages = {42-65},
  abstract = {{The Community Atmosphere Model (CAM), a 3-dimensional Earth-based
climate model, has been modified to simulate the dynamics of the Venus
atmosphere. The most current finite volume version of CAM is used with
Earth-related processes removed, parameters appropriate for Venus
introduced, and some basic physics approximations adopted. A simplified
Newtonian cooling approximation has been used for the radiation scheme.
We use a high resolution (1{\deg} by 1{\deg} in latitude and longitude) to
take account of small-scale dynamical processes that might be important
on Venus. A Rayleigh friction approach is used at the lower boundary to
represent surface drag, and a similar approach is implemented in the
uppermost few model levels providing a {\lsquo}sponge layer{\rsquo} to
prevent wave reflection from the upper boundary. The simulations
generate superrotation with wind velocities comparable to those measured
in the Venus atmosphere by probes and around 50-60\% of those measured by
cloud tracking. At cloud heights and above the atmosphere is always
superrotating with mid-latitude zonal jets that wax and wane on an
approximate 10 year cycle. However, below the clouds, the zonal winds
vary periodically on a decadal timescale between superrotation and
subrotation. Both subrotating and superrotating mid-latitude jets are
found in the approximate 40-60 km altitude range. The growth and decay
of the sub-cloud level jets also occur on the decadal timescale. Though
subrotating zonal winds are found below the clouds, the total angular
momentum of the atmosphere is always in the sense of superrotation. The
global relative angular momentum of the atmosphere oscillates with an
amplitude of about 5\% on the approximate 10 year timescale. Symmetric
instability in the near surface equatorial atmosphere might be the
source of the decadal oscillation in the atmospheric state. Analyses of
angular momentum transport show that all the jets are built up by
poleward transport by a meridional circulation while angular momentum is
redistributed to lower latitudes primarily by transient eddies. Possible
changes in the structure of Venus{\rsquo} cloud level mid-latitude jets
measured by Mariner 10, Pioneer Venus, and Venus Express suggest that a
cyclic variation similar to that found in the model might occur in the
real Venus atmosphere, although no subrotating winds below the cloud
level have been observed to date. Venus{\rsquo} atmosphere must be
observed over multi-year timescales and below the clouds if we are to
understand its dynamics.
  doi = {10.1016/j.icarus.2010.11.015},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Grassi}, D. and {Migliorini}, A. and {Montabone}, L. and {Lebonnois}, S. and 
	{Cardes{\`i}n-Moinelo}, A. and {Piccioni}, G. and {Drossart}, P. and 
	{Zasova}, L.~V.},
  title = {{Thermal structure of Venusian nighttime mesosphere as observed by VIRTIS-Venus Express}},
  journal = {Journal of Geophysical Research (Planets)},
  keywords = {Atmospheric Composition and Structure: Planetary atmospheres (5210, 5405, 5704), Planetary Sciences: Solid Surface Planets: Atmospheres (0343, 1060), Planetary Sciences: Solid Surface Planets: Remote sensing, Planetary Sciences: Solar System Objects: Venus},
  year = 2010,
  volume = 115,
  eid = {E09007},
  pages = {E09007},
  abstract = {{The mapping IR channel of the Visual and Infrared Thermal Imaging
Spectrometer (VIRTIS-M) on board the Venus Express spacecraft observes
the CO$_{2}$ band at 4.3 {$\mu$}m at a spectral resolution adequate
to retrieve the atmospheric temperature profiles in the 65-96 km
altitude range. Observations acquired in the period June 2006 to July
2008 were used to derive average temperature fields as a function of
latitude, subsolar longitude (i.e., local time, LT), and pressure.
Coverage presented here is limited to the nighttime because of the
adverse effects of daytime non-LTE emission on the retrieval procedure
and to southernmost latitudes because of the orientation of the
Venus-Express orbit. Maps of air temperature variability are also
presented as the standard deviation of the population included in each
averaging bin. At the 100 mbar level (about 65 km above the reference
surface), temperatures tend to decrease from the evening to the morning
side despite a local maximum observed around 20-21LT. The cold collar is
evident around 65S, with a minimum temperature at 3LT. Moving to higher
altitudes, local time trends become less evident at 12.6 mbar (about 75
km) where the temperature monotonically increases from middle latitudes
to the southern pole. Nonetheless, at this pressure level, two weaker
local time temperature minima are observed at 23LT and 2LT equatorward
of 60S. Local time trends in temperature reverse about 85 km, where the
morning side is the warmer. The variability at the 100 mbar level is
maximum around 80S and stronger toward the morning side. Moving to
higher altitudes, the morning side always shows the stronger
variability. Southward of 60S, standard deviation presents minimum
values around 12.6 mbar for all the local times.
  doi = {10.1029/2009JE003553},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Lebonnois}, S. and {Hourdin}, F. and {Eymet}, V. and {Crespin}, A. and 
	{Fournier}, R. and {Forget}, F.},
  title = {{Superrotation of Venus' atmosphere analyzed with a full general circulation model}},
  journal = {Journal of Geophysical Research (Planets)},
  keywords = {Planetary Sciences: Solid Surface Planets: Meteorology (3346), Atmospheric Processes: Planetary meteorology (5445, 5739), Atmospheric Composition and Structure: Planetary atmospheres (5210, 5405, 5704), Atmospheric Processes: General circulation (1223)},
  year = 2010,
  volume = 115,
  eid = {E06006},
  pages = {E06006},
  abstract = {{A general circulation model (GCM) has been developed for the Venus
atmosphere, from the surface up to 100 km altitude, based on the GCM
developed for Earth at our laboratory. Key features of this new GCM
include topography, diurnal cycle, dependence of the specific heat on
temperature, and a consistent radiative transfer module based on net
exchange rate matrices. This allows a consistent computation of the
temperature field, in contrast to previous GCMs of Venus atmosphere that
used simplified temperature forcing. The circulation is analyzed after
350 Venus days (111 Earth years). Superrotation is obtained above
roughly 40 km altitude. Below, the zonal wind remains very small
compared to observed values, which is a major pending question. The
meridional circulation consists of equator-to-pole cells, the dominant
one being located within the cloud layers. The modeled temperature
structure is globally consistent with observations, though discrepancies
persist in the stability of the lowest layers and equator-pole
temperature contrast within the clouds (10 K in the model compared to
the observed 40 K). In agreement with observational data, a convective
layer is found between the base of the clouds (around 47 km) and the
middle of the clouds (55-60 km altitude). The transport of angular
momentum is analyzed, and comparison between the reference simulation
and a simulation without diurnal cycle illustrates the role played by
thermal tides in the equatorial region. Without diurnal cycle, the
Gierasch-Rossow-Williams mechanism controls angular momentum transport.
The diurnal tides add a significant downward transport of momentum in
the equatorial region, causing low latitude momentum accumulation.
  doi = {10.1029/2009JE003458},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Eymet}, V. and {Fournier}, R. and {Dufresne}, J.-L. and {Lebonnois}, S. and 
	{Hourdin}, F. and {Bullock}, M.~A.},
  title = {{Net exchange parameterization of thermal infrared radiative transfer in Venus' atmosphere}},
  journal = {Journal of Geophysical Research (Planets)},
  keywords = {Atmospheric Processes: Radiative processes, Atmospheric Composition and Structure: Radiation: transmission and scattering, Global Change: Global climate models (3337, 4928), Atmospheric Composition and Structure: Cloud/radiation interaction, Mineral Physics: Optical, infrared, and Raman spectroscopy},
  year = 2009,
  volume = 114,
  number = e13,
  eid = {E11008},
  pages = {E11008},
  abstract = {{Thermal radiation within Venus atmosphere is analyzed in close details.
Prominent features are identified, which are then used to design a
parameterization (a highly simplified and yet accurate enough model) to
be used in General Circulation Models. The analysis is based on a net
exchange formulation, using a set of gaseous and cloud optical data
chosen among available referenced data. The accuracy of the proposed
parameterization methodology is controlled against Monte Carlo
simulations, assuming that the optical data are exact. Then, the
accuracy level corresponding to our present optical data choice is
discussed by comparison with available observations, concentrating on
the most unknown aspects of Venus thermal radiation, namely the deep
atmosphere opacity and the cloud composition and structure.
  doi = {10.1029/2008JE003276},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Wilson}, C.~F. and {Guerlet}, S. and {Irwin}, P.~G.~J. and 
	{Tsang}, C.~C.~C. and {Taylor}, F.~W. and {Carlson}, R.~W. and 
	{Drossart}, P. and {Piccioni}, G.},
  title = {{Evidence for anomalous cloud particles at the poles of Venus}},
  journal = {Journal of Geophysical Research (Planets)},
  keywords = {Planetary Sciences: Solar System Objects: Venus, Planetary Sciences: Comets and Small Bodies: Atmospheres (1060), Planetary Sciences: Comets and Small Bodies: Radiation and chemistry, Atmospheric Composition and Structure: Planetary atmospheres (5210, 5405, 5704), Atmospheric Composition and Structure: Aerosols and particles (0345, 4801, 4906)},
  year = 2008,
  volume = 113,
  eid = {E00B13},
  pages = {E00B13},
  abstract = {{An analysis of near-infrared emissions on the nightside of Venus
observed by the Visible and Infrared Thermal Imaging Spectrometer
(VIRTIS) instrument on board Venus Express reveals anomalous cloud
particles in the polar regions of Venus. These anomalous particles are
found within the centers of polar vortices at both poles and are either
larger or different in composition from those elsewhere in the planet.
We find no persistent latitudinal variation in cloud properties at low
to midlatitudes, nor do we find asymmetry between the southern and
northern hemispheres. These findings arise from analysis of the relative
brightness of 1.74 and 2.30 {$\mu$}m infrared radiation thermally emitted
from the deep atmosphere of Venus. Larger cloud particles cause
relatively more attenuation at 2.30 {$\mu$}m than at 1.74 {$\mu$}m, so we use
a ``size parameter,'' m = (I $_{1.74mum}$)/(I
$_{2.30mum}$)$^{0.53}$, as a proxy for particle size. This
methodology follows that of Carlson et al. (1993), supported by new
radiative transfer modeling.
  doi = {10.1029/2008JE003108},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{S{\'a}nchez-Lavega}, A. and {Hueso}, R. and {Piccioni}, G. and 
	{Drossart}, P. and {Peralta}, J. and {Pérez-Hoyos}, S. and 
	{Wilson}, C.~F. and {Taylor}, F.~W. and {Baines}, K.~H. and 
	{Luz}, D. and {Erard}, S. and {Lebonnois}, S.},
  title = {{Variable winds on Venus mapped in three dimensions}},
  journal = {\grl},
  keywords = {Atmospheric Composition and Structure: Planetary atmospheres (5210, 5405, 5704), Planetary Sciences: Solar System Objects: Venus, Atmospheric Processes: General circulation (1223), Atmospheric Processes: Planetary meteorology (5445, 5739)},
  year = 2008,
  volume = 35,
  eid = {L13204},
  pages = {L13204},
  abstract = {{We present zonal and meridional wind measurements at three altitude
levels within the cloud layers of Venus from cloud tracking using images
taken with the VIRTIS instrument on board Venus Express. At low
latitudes, zonal winds in the Southern hemisphere are nearly constant
with latitude with westward velocities of 105 ms$^{-1}$ at
cloud-tops (altitude \~{} 66 km) and 60-70 ms$^{-1}$ at the
cloud-base (altitude \~{} 47 km). At high latitudes, zonal wind speeds
decrease linearly with latitude with no detectable vertical wind shear
(values lower than 15 ms$^{-1}$), indicating the possibility of a
vertically coherent vortex structure. Meridional winds at the cloud-tops
are poleward with peak speed of 10 ms$^{-1}$ at 55{\deg} S but
below the cloud tops and averaged over the South hemisphere are found to
be smaller than 5 ms$^{-1}$. We also report the detection at
subpolar latitudes of wind variability due to the solar tide.
  doi = {10.1029/2008GL033817},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Lebonnois}, S.},
  title = {{The atmospheres of Mars, Venus and Titan: observed and modelled structures}},
  journal = {Acoustical Society of America Journal},
  year = 2008,
  volume = 123,
  pages = {3400},
  doi = {10.1121/1.2934094},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Bertaux}, J.-L. and {Vandaele}, A.-C. and {Korablev}, O. and 
	{Villard}, E. and {Fedorova}, A. and {Fussen}, D. and {Quémerais}, E. and 
	{Belyaev}, D. and {Mahieux}, A. and {Montmessin}, F. and {Muller}, C. and 
	{Neefs}, E. and {Nevejans}, D. and {Wilquet}, V. and {Dubois}, J.~P. and 
	{Hauchecorne}, A. and {Stepanov}, A. and {Vinogradov}, I. and 
	{Rodin}, A. and {Bertaux}, J.-L. and {Nevejans}, D. and {Korablev}, O. and 
	{Montmessin}, F. and {Vandaele}, A.-C. and {Fedorova}, A. and 
	{Cabane}, M. and {Chassefière}, E. and {Chaufray}, J.~Y. and 
	{Dimarellis}, E. and {Dubois}, J.~P. and {Hauchecorne}, A. and 
	{Leblanc}, F. and {Lefèvre}, F. and {Rannou}, P. and {Quémerais}, E. and 
	{Villard}, E. and {Fussen}, D. and {Muller}, C. and {Neefs}, E. and 
	{van Ransbeeck}, E. and {Wilquet}, V. and {Rodin}, A. and {Stepanov}, A. and 
	{Vinogradov}, I. and {Zasova}, L. and {Forget}, F. and {Lebonnois}, S. and 
	{Titov}, D. and {Rafkin}, S. and {Durry}, G. and {Gérard}, J.~C. and 
	{Sandel}, B.},
  title = {{A warm layer in Venus' cryosphere and high-altitude measurements of HF, HCl, H$_{2}$O and HDO}},
  journal = {\nat},
  year = 2007,
  volume = 450,
  pages = {646-649},
  abstract = {{Venus has thick clouds of H$_{2}$SO$_{4}$ aerosol particles
extending from altitudes of 40 to 60km. The 60-100km region (the
mesosphere) is a transition region between the 4day retrograde
superrotation at the top of the thick clouds and the solar-antisolar
circulation in the thermosphere (above 100km), which has upwelling over
the subsolar point and transport to the nightside. The mesosphere has a
light haze of variable optical thickness, with CO, SO$_{2}$, HCl,
HF, H$_{2}$O and HDO as the most important minor gaseous
constituents, but the vertical distribution of the haze and molecules is
poorly known because previous descent probes began their measurements at
or below 60km. Here we report the detection of an extensive layer of
warm air at altitudes 90-120km on the night side that we interpret as
the result of adiabatic heating during air subsidence. Such a strong
temperature inversion was not expected, because the night side of Venus
was otherwise so cold that it was named the `cryosphere' above 100km. We
also measured the mesospheric distributions of HF, HCl, H$_{2}$O
and HDO. HCl is less abundant than reported 40years ago.
HDO/H$_{2}$O is enhanced by a factor of \~{}2.5 with respect to the
lower atmosphere, and there is a general depletion of H$_{2}$O
around 80-90km for which we have no explanation.
  doi = {10.1038/nature05974},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Drossart}, P. and {Piccioni}, G. and {Gérard}, J.~C. and 
	{Lopez-Valverde}, M.~A. and {Sanchez-Lavega}, A. and {Zasova}, L. and 
	{Hueso}, R. and {Taylor}, F.~W. and {Bézard}, B. and {Adriani}, A. and 
	{Angrilli}, F. and {Arnold}, G. and {Baines}, K.~H. and {Bellucci}, G. and 
	{Benkhoff}, J. and {Bibring}, J.~P. and {Blanco}, A. and {Blecka}, M.~I. and 
	{Carlson}, R.~W. and {Coradini}, A. and {di Lellis}, A. and 
	{Encrenaz}, T. and {Erard}, S. and {Fonti}, S. and {Formisano}, V. and 
	{Fouchet}, T. and {Garcia}, R. and {Haus}, R. and {Helbert}, J. and 
	{Ignatiev}, N.~I. and {Irwin}, P. and {Langevin}, Y. and {Lebonnois}, S. and 
	{Luz}, D. and {Marinangeli}, L. and {Orofino}, V. and {Rodin}, A.~V. and 
	{Roos-Serote}, M.~C. and {Saggin}, B. and {Stam}, D.~M. and 
	{Titov}, D. and {Visconti}, G. and {Zambelli}, M. and {Tsang}, C. and 
	{Ammannito}, E. and {Barbis}, A. and {Berlin}, R. and {Bettanini}, C. and 
	{Boccaccini}, A. and {Bonnello}, G. and {Bouyé}, M. and 
	{Capaccioni}, F. and {Cardesin}, A. and {Carraro}, F. and {Cherubini}, G. and 
	{Cosi}, M. and {Dami}, M. and {de Nino}, M. and {Del Vento}, D. and 
	{di Giampietro}, M. and {Donati}, A. and {Dupuis}, O. and {Espinasse}, S. and 
	{Fabbri}, A. and {Fave}, A. and {Ficai Veltroni}, I. and {Filacchione}, G. and 
	{Garceran}, K. and {Ghomchi}, Y. and {Giustizi}, M. and {Gondet}, B. and 
	{Hello}, Y. and {Henry}, F. and {Hofer}, S. and {Huntzinger}, G. and 
	{Kachlicki}, J. and {Knoll}, R. and {Kouach}, D. and {Mazzoni}, A. and 
	{Melchiorri}, R. and {Mondello}, G. and {Monti}, F. and {Neumann}, C. and 
	{Nuccilli}, F. and {Parisot}, J. and {Pasqui}, C. and {Perferi}, S. and 
	{Peter}, G. and {Piacentino}, A. and {Pompei}, C. and {Réess}, J.-M. and 
	{Rivet}, J.-P. and {Romano}, A. and {Russ}, N. and {Santoni}, M. and 
	{Scarpelli}, A. and {Sémery}, A. and {Soufflot}, A. and 
	{Stefanovitch}, D. and {Suetta}, E. and {Tarchi}, F. and {Tonetti}, N. and 
	{Tosi}, F. and {Ulmer}, B.},
  title = {{A dynamic upper atmosphere of Venus as revealed by VIRTIS on Venus Express}},
  journal = {\nat},
  year = 2007,
  volume = 450,
  pages = {641-645},
  abstract = {{The upper atmosphere of a planet is a transition region in which energy
is transferred between the deeper atmosphere and outer space. Molecular
emissions from the upper atmosphere (90-120km altitude) of Venus can be
used to investigate the energetics and to trace the circulation of this
hitherto little-studied region. Previous spacecraft and ground-based
observations of infrared emission from CO$_{2}$, O$_{2}$ and
NO have established that photochemical and dynamic activity controls the
structure of the upper atmosphere of Venus. These data, however, have
left unresolved the precise altitude of the emission owing to a lack of
data and of an adequate observing geometry. Here we report measurements
of day-side CO$_{2}$ non-local thermodynamic equilibrium emission
at 4.3{\micro}m, extending from 90 to 120km altitude, and of night-side
O$_{2}$ emission extending from 95 to 100km. The CO$_{2}$
emission peak occurs at \~{}115km and varies with solar zenith angle over a
range of \~{}10km. This confirms previous modelling, and permits the
beginning of a systematic study of the variability of the emission. The
O$_{2}$ peak emission happens at 96km+/-1km, which is consistent
with three-body recombination of oxygen atoms transported from the day
side by a global thermospheric sub-solar to anti-solar circulation, as
previously predicted.
  doi = {10.1038/nature06140},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Piccioni}, G. and {Drossart}, P. and {Sanchez-Lavega}, A. and 
	{Hueso}, R. and {Taylor}, F.~W. and {Wilson}, C.~F. and {Grassi}, D. and 
	{Zasova}, L. and {Moriconi}, M. and {Adriani}, A. and {Lebonnois}, S. and 
	{Coradini}, A. and {Bézard}, B. and {Angrilli}, F. and {Arnold}, G. and 
	{Baines}, K.~H. and {Bellucci}, G. and {Benkhoff}, J. and {Bibring}, J.~P. and 
	{Blanco}, A. and {Blecka}, M.~I. and {Carlson}, R.~W. and {di Lellis}, A. and 
	{Encrenaz}, T. and {Erard}, S. and {Fonti}, S. and {Formisano}, V. and 
	{Fouchet}, T. and {Garcia}, R. and {Haus}, R. and {Helbert}, J. and 
	{Ignatiev}, N.~I. and {Irwin}, P.~G.~J. and {Langevin}, Y. and 
	{Lopez-Valverde}, M.~A. and {Luz}, D. and {Marinangeli}, L. and 
	{Orofino}, V. and {Rodin}, A.~V. and {Roos-Serote}, M.~C. and 
	{Saggin}, B. and {Stam}, D.~M. and {Titov}, D. and {Visconti}, G. and 
	{Zambelli}, M. and {Ammannito}, E. and {Barbis}, A. and {Berlin}, R. and 
	{Bettanini}, C. and {Boccaccini}, A. and {Bonnello}, G. and 
	{Bouye}, M. and {Capaccioni}, F. and {Cardesin Moinelo}, A. and 
	{Carraro}, F. and {Cherubini}, G. and {Cosi}, M. and {Dami}, M. and 
	{de Nino}, M. and {Del Vento}, D. and {di Giampietro}, M. and 
	{Donati}, A. and {Dupuis}, O. and {Espinasse}, S. and {Fabbri}, A. and 
	{Fave}, A. and {Veltroni}, I.~F. and {Filacchione}, G. and {Garceran}, K. and 
	{Ghomchi}, Y. and {Giustini}, M. and {Gondet}, B. and {Hello}, Y. and 
	{Henry}, F. and {Hofer}, S. and {Huntzinger}, G. and {Kachlicki}, J. and 
	{Knoll}, R. and {Driss}, K. and {Mazzoni}, A. and {Melchiorri}, R. and 
	{Mondello}, G. and {Monti}, F. and {Neumann}, C. and {Nuccilli}, F. and 
	{Parisot}, J. and {Pasqui}, C. and {Perferi}, S. and {Peter}, G. and 
	{Piacentino}, A. and {Pompei}, C. and {Reess}, J.-M. and {Rivet}, J.-P. and 
	{Romano}, A. and {Russ}, N. and {Santoni}, M. and {Scarpelli}, A. and 
	{Semery}, A. and {Soufflot}, A. and {Stefanovitch}, D. and {Suetta}, E. and 
	{Tarchi}, F. and {Tonetti}, N. and {Tosi}, F. and {Ulmer}, B.
  title = {{South-polar features on Venus similar to those near the north pole}},
  journal = {\nat},
  year = 2007,
  volume = 450,
  pages = {637-640},
  abstract = {{Venus has no seasons, slow rotation and a very massive atmosphere, which
is mainly carbon dioxide with clouds primarily of sulphuric acid
droplets. Infrared observations by previous missions to Venus revealed a
bright `dipole' feature surrounded by a cold `collar' at its north pole.
The polar dipole is a `double-eye' feature at the centre of a vast
vortex that rotates around the pole, and is possibly associated with
rapid downwelling. The polar cold collar is a wide, shallow river of
cold air that circulates around the polar vortex. One outstanding
question has been whether the global circulation was symmetric, such
that a dipole feature existed at the south pole. Here we report
observations of Venus' south-polar region, where we have seen clouds
with morphology much like those around the north pole, but rotating
somewhat faster than the northern dipole. The vortex may extend down to
the lower cloud layers that lie at about 50km height and perhaps deeper.
The spectroscopic properties of the clouds around the south pole are
compatible with a sulphuric acid composition.
  doi = {10.1038/nature06209},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Bertaux}, J.-L. and {Nevejans}, D. and {Korablev}, O. and {Villard}, E. and 
	{Quémerais}, E. and {Neefs}, E. and {Montmessin}, F. and 
	{Leblanc}, F. and {Dubois}, J.~P. and {Dimarellis}, E. and {Hauchecorne}, A. and 
	{Lefèvre}, F. and {Rannou}, P. and {Chaufray}, J.~Y. and 
	{Cabane}, M. and {Cernogora}, G. and {Souchon}, G. and {Semelin}, F. and 
	{Reberac}, A. and {Van Ransbeek}, E. and {Berkenbosch}, S. and 
	{Clairquin}, R. and {Muller}, C. and {Forget}, F. and {Hourdin}, F. and 
	{Talagrand}, O. and {Rodin}, A. and {Fedorova}, A. and {Stepanov}, A. and 
	{Vinogradov}, I. and {Kiselev}, A. and {Kalinnikov}, Y. and 
	{Durry}, G. and {Sandel}, B. and {Stern}, A. and {Gérard}, J.~C.
  title = {{SPICAV on Venus Express: Three spectrometers to study the global structure and composition of the Venus atmosphere}},
  journal = {\planss},
  year = 2007,
  volume = 55,
  pages = {1673-1700},
  abstract = {{Spectroscopy for the investigation of the characteristics of the
atmosphere of Venus (SPICAV) is a suite of three spectrometers in the UV
and IR range with a total mass of 13.9 kg flying on the Venus Express
(VEX) orbiter, dedicated to the study of the atmosphere of Venus from
ground level to the outermost hydrogen corona at more than 40,000 km. It
is derived from the SPICAM instrument already flying on board Mars
Express (MEX) with great success, with the addition of a new IR
high-resolution spectrometer, solar occultation IR (SOIR), working in
the solar occultation mode. The instrument consists of three
spectrometers and a simple data processing unit providing the interface
of these channels with the spacecraft. A UV spectrometer (118-320 nm,
resolution 1.5 nm) is identical to the MEX version. It is dedicated to
nadir viewing, limb viewing and vertical profiling by stellar and solar
occultation. In nadir orientation, SPICAV UV will analyse the albedo
spectrum (solar light scattered back from the clouds) to retrieve SO
$_{2}$, and the distribution of the UV-blue absorber (of still
unknown origin) on the dayside with implications for cloud structure and
atmospheric dynamics. On the nightside, {$\gamma$} and {$\delta$} bands of NO
will be studied, as well as emissions produced by electron
precipitations. In the stellar occultation mode the UV sensor will
measure the vertical profiles of CO $_{2}$, temperature, SO
$_{2}$, SO, clouds and aerosols. The density/temperature profiles
obtained with SPICAV will constrain and aid in the development of
dynamical atmospheric models, from cloud top ({\tilde}60 km) to 160 km in
the atmosphere. This is essential for future missions that would rely on
aerocapture and aerobraking. UV observations of the upper atmosphere
will allow studies of the ionosphere through the emissions of CO, CO
$^{+}$, and CO $_{2}$$^{+}$, and its direct
interaction with the solar wind. It will study the H corona, with its
two different scale heights, and it will allow a better understanding of
escape mechanisms and estimates of their magnitude, crucial for insight
into the long-term evolution of the atmosphere. The SPICAV VIS-IR sensor
(0.7-1.7 {$\mu$}m, resolution 0.5-1.2 nm) employs a pioneering technology:
an acousto-optical tunable filter (AOTF). On the nightside, it will
study the thermal emission peeping through the clouds, complementing the
observations of both VIRTIS and Planetary Fourier Spectrometer (PFS) on
VEX. In solar occultation mode this channel will study the vertical
structure of H $_{2}$O, CO $_{2}$, and aerosols. The SOIR
spectrometer is a new solar occultation IR spectrometer in the range
{$\lambda$}=2.2-4.3 {$\mu$}m, with a spectral resolution {$\lambda$}/{$\Delta$}
{$\lambda$}$\gt$15,000, the highest on board VEX. This new concept includes
a combination of an echelle grating and an AOTF crystal to sort out one
order at a time. The main objective is to measure HDO and H
$_{2}$O in solar occultation, in order to characterize the escape
of D atoms from the upper atmosphere and give more insight about the
evolution of water on Venus. It will also study isotopes of CO
$_{2}$ and minor species, and provides a sensitive search for new
species in the upper atmosphere of Venus. It will attempt to measure
also the nightside emission, which would allow a sensitive measurement
of HDO in the lower atmosphere, to be compared to the ratio in the upper
atmosphere, and possibly discover new minor atmospheric constituents.
  doi = {10.1016/j.pss.2007.01.016},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Drossart}, P. and {Piccioni}, G. and {Adriani}, A. and {Angrilli}, F. and 
	{Arnold}, G. and {Baines}, K.~H. and {Bellucci}, G. and {Benkhoff}, J. and 
	{Bézard}, B. and {Bibring}, J.-P. and {Blanco}, A. and {Blecka}, M.~I. and 
	{Carlson}, R.~W. and {Coradini}, A. and {Di Lellis}, A. and 
	{Encrenaz}, T. and {Erard}, S. and {Fonti}, S. and {Formisano}, V. and 
	{Fouchet}, T. and {Garcia}, R. and {Haus}, R. and {Helbert}, J. and 
	{Ignatiev}, N.~I. and {Irwin}, P.~G.~J. and {Langevin}, Y. and 
	{Lebonnois}, S. and {Lopez-Valverde}, M.~A. and {Luz}, D. and 
	{Marinangeli}, L. and {Orofino}, V. and {Rodin}, A.~V. and {Roos-Serote}, M.~C. and 
	{Saggin}, B. and {Sanchez-Lavega}, A. and {Stam}, D.~M. and 
	{Taylor}, F.~W. and {Titov}, D. and {Visconti}, G. and {Zambelli}, M. and 
	{Hueso}, R. and {Tsang}, C.~C.~C. and {Wilson}, C.~F. and {Afanasenko}, T.~Z.
  title = {{Scientific goals for the observation of Venus by VIRTIS on ESA/Venus express mission}},
  journal = {\planss},
  year = 2007,
  volume = 55,
  pages = {1653-1672},
  abstract = {{The Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on board
the ESA/Venus Express mission has technical specifications well suited
for many science objectives of Venus exploration. VIRTIS will both
comprehensively explore a plethora of atmospheric properties and
processes and map optical properties of the surface through its three
channels, VIRTIS-M-vis (imaging spectrometer in the 0.3-1 {$\mu$}m range),
VIRTIS-M-IR (imaging spectrometer in the 1-5 {$\mu$}m range) and VIRTIS-H
(aperture high-resolution spectrometer in the 2-5 {$\mu$}m range). The
atmospheric composition below the clouds will be repeatedly measured in
the night side infrared windows over a wide range of latitudes and
longitudes, thereby providing information on Venus's chemical cycles. In
particular, CO, H $_{2}$O, OCS and SO $_{2}$ can be studied.
The cloud structure will be repeatedly mapped from the brightness
contrasts in the near-infrared night side windows, providing new
insights into Venusian meteorology. The global circulation and local
dynamics of Venus will be extensively studied from infrared and visible
spectral images. The thermal structure above the clouds will be
retrieved in the night side using the 4.3 {$\mu$}m fundamental band of CO
$_{2}$. The surface of Venus is detectable in the short-wave
infrared windows on the night side at 1.01, 1.10 and 1.18 {$\mu$}m,
providing constraints on surface properties and the extent of active
volcanism. Many more tentative studies are also possible, such as
lightning detection, the composition of volcanic emissions, and
mesospheric wave propagation.
  doi = {10.1016/j.pss.2007.01.003},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}
  author = {{Formisano}, V. and {Angrilli}, F. and {Arnold}, G. and {Atreya}, S. and 
	{Baines}, K.~H. and {Bellucci}, G. and {Bezard}, B. and {Billebaud}, F. and 
	{Biondi}, D. and {Blecka}, M.~I. and {Colangeli}, L. and {Comolli}, L. and 
	{Crisp}, D. and {D'Amore}, M. and {Encrenaz}, T. and {Ekonomov}, A. and 
	{Esposito}, F. and {Fiorenza}, C. and {Fonti}, S. and {Giuranna}, M. and 
	{Grassi}, D. and {Grieger}, B. and {Grigoriev}, A. and {Helbert}, J. and 
	{Hirsch}, H. and {Ignatiev}, N. and {Jurewicz}, A. and {Khatuntsev}, I. and 
	{Lebonnois}, S. and {Lellouch}, E. and {Mattana}, A. and {Maturilli}, A. and 
	{Mencarelli}, E. and {Michalska}, M. and {Lopez Moreno}, J. and 
	{Moshkin}, B. and {Nespoli}, F. and {Nikolsky}, Y. and {Nuccilli}, F. and 
	{Orleanski}, P. and {Palomba}, E. and {Piccioni}, G. and {Rataj}, M. and 
	{Rinaldi}, G. and {Rossi}, M. and {Saggin}, B. and {Stam}, D. and 
	{Titov}, D. and {Visconti}, G. and {Zasova}, L.},
  title = {{The planetary fourier spectrometer (PFS) onboard the European Venus Express mission}},
  journal = {\planss},
  year = 2006,
  volume = 54,
  pages = {1298-1314},
  abstract = {{The planetary fourier spectrometer (PFS) for the Venus Express mission
is an infrared spectrometer optimized for atmospheric studies. This
instrument has a short wavelength (SW) channel that covers the spectral
range from 1700 to 11400 cm $^{-1}$ (0.9-5.5 {$\mu$}m) and a long
wavelength (LW) channel that covers 250-1700 cm $^{-1}$ (5.5-45
{$\mu$}m). Both channels have a uniform spectral resolution of 1.3 cm
$^{-1}$. The instrument field of view FOV is about 1.6 {\deg}
(FWHM) for the short wavelength channel and 2.8 {\deg} for the LW channel
which corresponds to a spatial resolution of 7 and 12 km when Venus is
observed from an altitude of 250 km. PFS can provide unique data
necessary to improve our knowledge not only of the atmospheric
properties but also surface properties (temperature) and the
surface-atmosphere interaction (volcanic activity). PFS works primarily
around the pericentre of the orbit, only occasionally observing Venus
from larger distances. Each measurements takes 4.5 s, with a repetition
time of 11.5 s. By working roughly 1.5 h around pericentre, a total of
460 measurements per orbit will be acquired plus 60 for calibrations.
PFS is able to take measurements at all local times, enabling the
retrieval of atmospheric vertical temperature profiles on both the day
and the night side. The PFS measures a host of atmospheric and surface
phenomena on Venus. These include the:(1) thermal surface flux at
several wavelengths near 1 {$\mu$}m, with concurrent constraints on surface
temperature and emissivity (indicative of composition); (2) the
abundances of several highly-diagnostic trace molecular species; (3)
atmospheric temperatures from 55 to 100 km altitude; (4) cloud opacities
and cloud-tracked winds in the lower-level cloud layers near 50-km
altitudes; (5) cloud top pressures of the uppermost haze/cloud region
near 70-80 km altitude; and (6) oxygen airglow near the 100 km level.
All of these will be observed repeatedly during the 500-day nominal
mission of Venus Express to yield an increased understanding of
meteorological, dynamical, photochemical, and thermo-chemical processes
in the Venus atmosphere. Additionally, PFS will search for and
characterize current volcanic activity through spatial and temporal
anomalies in both the surface thermal flux and the abundances of
volcanic trace species in the lower atmosphere. Measurement of the 15
{$\mu$}m CO $_{2}$ band is very important. Its profile gives, by
means of a complex temperature profile retrieval technique, the vertical
pressure-temperature relation, basis of the global atmospheric study.
PFS is made of four modules called O, E, P and S being, respectively,
the interferometer and proximity electronics, the digital control unit,
the power supply and the pointing device.
  doi = {10.1016/j.pss.2006.04.033},
  adsurl = {},
  adsnote = {Provided by the SAO/NASA Astrophysics Data System}