pubgcm0.bib
@comment{{This file has been generated by bib2bib 1.96}}
@comment{{Command line: bib2bib -c 'not journal:"Discussions"' -c 'not title:"Correction to"' -c 'abstract:"global climate model" or abstract:"GCM"' -c $type="ARTICLE" -oc pubgcm0.txt -ob pubgcm0.bib leconte.link.bib}}
@article{2019ApJ...875...46Y,
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 = {https://ui.adsabs.harvard.edu/abs/2019ApJ...875...46Y},
localpdf = {https://ui.adsabs.harvard.edu/abs/2019ApJ...875...46Y.pdf},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2018A&A...612A..86T,
author = {{Turbet}, M. and {Bolmont}, E. and {Leconte}, J. and {Forget}, F. and
{Selsis}, F. and {Tobie}, G. and {Caldas}, A. and {Naar}, J. and
{Gillon}, M.},
title = {{Modeling climate diversity, tidal dynamics and the fate of volatiles on TRAPPIST-1 planets}},
journal = {\aap},
archiveprefix = {arXiv},
eprint = {1707.06927},
primaryclass = {astro-ph.EP},
keywords = {stars: individual: TRAPPIST-1, planets and satellites: terrestrial planets, planets and satellites: atmospheres, planets and satellites: dynamical evolution and stability, astrobiology},
year = 2018,
volume = 612,
eid = {A86},
pages = {A86},
abstract = {{TRAPPIST-1 planets are invaluable for the study of comparative planetary
science outside our solar system and possibly habitability. Both transit
timing variations (TTV) of the planets and the compact, resonant
architecture of the system suggest that TRAPPIST-1 planets could be
endowed with various volatiles today. First, we derived from N-body
simulations possible planetary evolution scenarios, and show that all
the planets are likely in synchronous rotation. We then used a versatile
3D global climate model (GCM) to explore the possible climates of cool
planets around cool stars, with a focus on the TRAPPIST-1 system. We
investigated the conditions required for cool planets to prevent
possible volatile species to be lost permanently by surface
condensation, irreversible burying or photochemical destruction. We also
explored the resilience of the same volatiles (when in condensed phase)
to a runaway greenhouse process. We find that background atmospheres
made of N$_{2}$, CO, or O$_{2}$ are rather resistant to
atmospheric collapse. However, even if TRAPPIST-1 planets were able to
sustain a thick background atmosphere by surviving early X/EUV radiation
and stellar wind atmospheric erosion, it is difficult for them to
accumulate significant greenhouse gases like CO$_{2}$,
CH$_{4}$, or NH$_{3}$. CO$_{2}$ can easily condense on
the permanent nightside, forming CO$_{2}$ ice glaciers that would
flow toward the substellar region. A complete CO$_{2}$ ice surface
cover is theoretically possible on TRAPPIST-1g and h only, but
CO$_{2}$ ices should be gravitationally unstable and get buried
beneath the water ice shell in geologically short timescales. Given
TRAPPIST-1 planets large EUV irradiation (at least 10$^{3}$
{\times} Titan's flux), CH$_{4}$ and NH$_{3}$ are
photodissociated rapidly and are thus hard to accumulate in the
atmosphere. Photochemical hazes could then sedimentate and form a
surface layer of tholins that would progressively thicken over the age
of the TRAPPIST-1 system. Regarding habitability, we confirm that few
bars of CO$_{2}$ would suffice to warm the surface of TRAPPIST-1f
and g above the melting point of water. We also show that TRAPPIST-1e is
a remarkable candidate for surface habitability. If the planet is today
synchronous and abundant in water, then it should very likely sustain
surface liquid water at least in the substellar region, whatever the
atmosphere considered.
}},
doi = {10.1051/0004-6361/201731620},
adsurl = {https://ui.adsabs.harvard.edu/abs/2018A%26A...612A..86T},
localpdf = {https://ui.adsabs.harvard.edu/abs/2018A_26A...612A..86T.pdf},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2017E&PSL.476...11T,
author = {{Turbet}, M. and {Forget}, F. and {Leconte}, J. and {Charnay}, B. and
{Tobie}, G.},
title = {{CO$_{2}$ condensation is a serious limit to the deglaciation of Earth-like planets}},
journal = {Earth and Planetary Science Letters},
archiveprefix = {arXiv},
eprint = {1703.04624},
primaryclass = {astro-ph.EP},
keywords = {climate, snowball, exoplanet, CO$_{2}$ condensation, habitability, climate cycling},
year = 2017,
volume = 476,
pages = {11-21},
abstract = {{It is widely believed that the carbonate-silicate cycle is the main
agent, through volcanism, to trigger deglaciations by CO$_{2}$
greenhouse warming on Earth and on Earth-like planets when they get in a
frozen state. Here we use a 3D Global Climate Model to simulate the
ability of planets initially completely frozen to escape from glaciation
episodes by accumulating enough gaseous CO$_{2}$. The model
includes CO$_{2}$ condensation and sublimation processes and the
water cycle. We find that planets with Earth-like characteristics (size,
mass, obliquity, rotation rate, etc.) orbiting a Sun-like star may never
be able to escape from a glaciation era, if their orbital distance is
greater than {\sim}1.27 Astronomical Units (Flux $\lt$ 847
Wm$^{-2}$ or 62\% of the Solar constant), because CO$_{2}$
would condense at the poles - here the cold traps - forming permanent
CO$_{2}$ ice caps. This limits the amount of CO$_{2}$ in the
atmosphere and thus its greenhouse effect. Furthermore, our results
indicate that for (1) high rotation rates (P$_{rot}$ $\lt$ 24 h),
(2) low obliquity (obliquity $\lt$23.5{\deg}), (3) low background gas
partial pressures ($\lt$1 bar), and (4) high water ice albedo
(H$_{2}$O albedo $\gt$ 0.6), this critical limit could occur at a
significantly lower equivalent distance (or higher insolation). For each
possible configuration, we show that the amount of CO$_{2}$ that
can be trapped in the polar caps depends on the efficiency of
CO$_{2}$ ice to flow laterally as well as its gravitational
stability relative to subsurface water ice. We find that a frozen
Earth-like planet located at 1.30 AU of a Sun-like star could store as
much as 1.5, 4.5 and 15 bars of dry ice at the poles, for internal heat
fluxes of 100, 30 and 10 mW m$^{-2}$, respectively. But these
amounts are in fact lower limits. For planets with a significant water
ice cover, we show that CO$_{2}$ ice deposits should be
gravitationally unstable. They get buried beneath the water ice cover in
geologically short timescales of {\sim}10$^{4}$ yrs, mainly
controlled by the viscosity of water ice. CO$_{2}$ would be
permanently sequestered underneath the water ice cover, in the form of
CO$_{2}$ liquids, CO$_{2}$ clathrate hydrates and/or
dissolved in subglacial water reservoirs (if any). This would
considerably increase the amount of CO$_{2}$ trapped and further
reduce the probability of deglaciation.
}},
doi = {10.1016/j.epsl.2017.07.050},
adsurl = {https://ui.adsabs.harvard.edu/abs/2017E%26PSL.476...11T},
localpdf = {https://ui.adsabs.harvard.edu/abs/2017E_26PSL.476...11T.pdf},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2017Icar..287...54F,
author = {{Forget}, F. and {Bertrand}, T. and {Vangvichith}, M. and {Leconte}, J. and
{Millour}, E. and {Lellouch}, E.},
title = {{A post-new horizons global climate model of Pluto including the N$_{2}$, CH$_{4}$ and CO cycles}},
journal = {\icarus},
keywords = {Pluto, Pluto, atmosphere, Atmospheres, composition, Atmospheres, dynamics},
year = 2017,
volume = 287,
pages = {54-71},
abstract = {{We have built a new 3D Global Climate Model (GCM) to simulate Pluto as
observed by New Horizons in 2015. All key processes are parametrized on
the basis of theoretical equations, including atmospheric dynamics and
transport, turbulence, radiative transfer, molecular conduction, as well
as phases changes for N$_{2}$, CH$_{2}$ and CO. Pluto's
climate and ice cycles are found to be very sensitive to model
parameters and initial states. Nevertheless, a reference simulation is
designed by running a fast, reduced version of the GCM with simplified
atmospheric transport for 40,000 Earth years to initialize the surface
ice distribution and sub-surface temperatures, from which a
28-Earth-year full GCM simulation is performed. Assuming a topographic
depression in a Sputnik-planum (SP)-like crater on the anti-Charon
hemisphere, a realistic Pluto is obtained, with most N$_{2}$ and
CO ices accumulated in the crater, methane frost covering both
hemispheres except for the equatorial regions, and a surface pressure
near 1.1 Pa in 2015 with an increase between 1988 and 2015, as reported
from stellar occultations. Temperature profiles are in qualitative
agreement with the observations. In particular, a cold atmospheric layer
is obtained in the lowest kilometers above Sputnik Planum, as observed
by New Horizons's REX experiment. It is shown to result from the
combined effect of the topographic depression and N$_{2}$ daytime
sublimation. In the reference simulation with surface N$_{2}$ ice
exclusively present in Sputnik Planum, the global circulation is only
forced by radiative heating gradients and remains relatively weak.
Surface winds are locally induced by topography slopes and by
N$_{2}$ condensation and sublimation around Sputnik Planum.
However, the circulation can be more intense depending on the exact
distribution of surface N$_{2}$ frost. This is illustrated in an
alternative simulation with N$_{2}$ condensing in the South Polar
regions and N$_{2}$ frost covering latitudes between 35{\deg}N and
48{\deg}N. A global condensation flow is then created, inducing strong
surface winds everywhere, a prograde jet in the southern high latitudes,
and an equatorial superrotation likely forced by barotropic
instabilities in the southern jet. Using realistic parameters, the GCM
predict atmospheric concentrations of CO and CH$_{4}$ in good
agreement with the observations. N$_{2}$ and CO do not condense in
the atmosphere, but CH$_{4}$ ice clouds can form during daytime at
low altitude near the regions covered by N$_{2}$ ice (assuming
that nucleation is efficient enough). This global climate model can be
used to study many aspects of the Pluto environment. For instance,
organic hazes are included in the GCM and analysed in a companion paper
(Bertrand and Forget, Icarus, this issue).
}},
doi = {10.1016/j.icarus.2016.11.038},
adsurl = {https://ui.adsabs.harvard.edu/abs/2017Icar..287...54F},
localpdf = {https://ui.adsabs.harvard.edu/abs/2017Icar..287...54F.pdf},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2016A&A...596A.112T,
author = {{Turbet}, M. and {Leconte}, J. and {Selsis}, F. and {Bolmont}, E. and
{Forget}, F. and {Ribas}, I. and {Raymond}, S.~N. and {Anglada-Escudé}, G.
},
title = {{The habitability of Proxima Centauri b. II. Possible climates and observability}},
journal = {\aap},
archiveprefix = {arXiv},
eprint = {1608.06827},
primaryclass = {astro-ph.EP},
keywords = {stars: individual: Proxima Cen, planets and satellites: individual: Proxima Cen b, planets and satellites: atmospheres, planets and satellites: terrestrial planets, planets and satellites: detection, astrobiology},
year = 2016,
volume = 596,
eid = {A112},
pages = {A112},
abstract = {{Radial velocity monitoring has found the signature of a Msini =
1.3M$_{⊕}$ planet located within the habitable zone (HZ) of
Proxima Centauri. Despite a hotter past and an active host star, the
planet Proxima b could have retained enough volatiles to sustain surface
habitability. Here we use a 3D Global Climate Model (GCM) to simulate
the atmosphere and water cycle of Proxima b for its two likely rotation
modes (1:1 and 3:2 spin-orbit resonances), while varying the
unconstrained surface water inventory and atmospheric greenhouse effect.
Any low-obliquity, low-eccentricity planet within the HZ of its star
should be in one of the climate regimes discussed here. We find that a
broad range of atmospheric compositions allow surface liquid water. On a
tidally locked planet with sufficient surface water inventory, liquid
water is always present, at least in the substellar region. With a
non-synchronous rotation, this requires a minimum greenhouse warming (
10 mbar of CO$_{2}$ and 1 bar of N$_{2}$). If the planet is
dryer, 0.5 bar or 1.5 bars of CO$_{2}$ (for asynchronous or
synchronous rotation, respectively) suffice to prevent the trapping of
any arbitrary, small water inventory into polar or nightside ice caps.
We produce reflection and emission spectra and phase curves for the
simulated climates. We find that atmospheric characterization will be
possible via direct imaging with forthcoming large telescopes. The
angular separation of 7{$\lambda$}/D at 1 {$\mu$}m (with the E-ELT) and a
contrast of 10$^{-7}$ will enable high-resolution spectroscopy
and the search for molecular signatures, including H$_{2}$O,
O$_{2}$, and CO$_{2}$. The observation of thermal phase
curves can be attempted with the James Webb Space Telescope, thanks to a
contrast of 2 {\times} 10$^{-5}$ at 10 {$\mu$}m. Proxima b will also
be an exceptional target for future IR interferometers. Within a decade
it will be possible to image Proxima b and possibly determine whether
the surface of this exoplanet is habitable.
}},
doi = {10.1051/0004-6361/201629577},
adsurl = {https://ui.adsabs.harvard.edu/abs/2016A%26A...596A.112T},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016A_26A...596A.112T.pdf},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2016ApJ...826..222Y,
author = {{Yang}, J. and {Leconte}, J. and {Wolf}, E.~T. and {Goldblatt}, C. and
{Feldl}, N. and {Merlis}, T. and {Wang}, Y. and {Koll}, D.~D.~B. and
{Ding}, F. and {Forget}, F. and {Abbot}, D.~S.},
title = {{Differences in Water Vapor Radiative Transfer among 1D Models Can Significantly Affect the Inner Edge of the Habitable Zone}},
journal = {\apj},
archiveprefix = {arXiv},
eprint = {1809.01397},
primaryclass = {astro-ph.EP},
keywords = {astrobiology, methods: numerical, planets and satellites: atmospheres, planets and satellites: general, planets and satellites: terrestrial planets, radiative transfer},
year = 2016,
volume = 826,
eid = {222},
pages = {222},
abstract = {{An accurate estimate of the inner edge of the habitable zone is critical
for determining which exoplanets are potentially habitable and for
designing future telescopes to observe them. Here, we explore
differences in estimating the inner edge among seven one-dimensional
radiative transfer models: two line-by-line codes (SMART and LBLRTM) as
well as five band codes (CAM3, CAM4\_Wolf, LMDG, SBDART, and AM2) that
are currently being used in global climate models. We compare radiative
fluxes and spectra in clear-sky conditions around G and M stars, with
fixed moist adiabatic profiles for surface temperatures from 250 to 360
K. We find that divergences among the models arise mainly from large
uncertainties in water vapor absorption in the window region (10 {$\mu$}m)
and in the region between 0.2 and 1.5 {$\mu$}m. Differences in outgoing
longwave radiation increase with surface temperature and reach 10-20 W
m$^{-2}$ differences in shortwave reach up to 60 W m$^{-2}$,
especially at the surface and in the troposphere, and are larger for an
M-dwarf spectrum than a solar spectrum. Differences between the two
line-by-line models are significant, although smaller than among the
band models. Our results imply that the uncertainty in estimating the
insolation threshold of the inner edge (the runaway greenhouse limit)
due only to clear-sky radiative transfer is {\ap}10\% of modern
Earth{\rsquo}s solar constant (I.e., {\ap}34 W m$^{-2}$ in global
mean) among band models and {\ap}3\% between the two line-by-line models.
These comparisons show that future work is needed that focuses on
improving water vapor absorption coefficients in both shortwave and
longwave, as well as on increasing the resolution of stellar spectra in
broadband models.
}},
doi = {10.3847/0004-637X/826/2/222},
adsurl = {https://ui.adsabs.harvard.edu/abs/2016ApJ...826..222Y},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016ApJ...826..222Y.pdf},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2016A&A...591A.106B,
author = {{Bolmont}, E. and {Libert}, A.-S. and {Leconte}, J. and {Selsis}, F.
},
title = {{Habitability of planets on eccentric orbits: Limits of the mean flux approximation}},
journal = {\aap},
archiveprefix = {arXiv},
eprint = {1604.06091},
primaryclass = {astro-ph.EP},
keywords = {planets and satellites: atmospheres, planets and satellites: terrestrial planets, methods: numerical},
year = 2016,
volume = 591,
eid = {A106},
pages = {A106},
abstract = {{Unlike the Earth, which has a small orbital eccentricity, some
exoplanets discovered in the insolation habitable zone (HZ) have high
orbital eccentricities (e.g., up to an eccentricity of \~{}0.97 for HD
20782 b). This raises the question of whether these planets have surface
conditions favorable to liquid water. In order to assess the
habitability of an eccentric planet, the mean flux approximation is
often used. It states that a planet on an eccentric orbit is called
habitable if it receives on average a flux compatible with the presence
of surface liquid water. However, because the planets experience
important insolation variations over one orbit and even spend some time
outside the HZ for high eccentricities, the question of their
habitability might not be as straightforward. We performed a set of
simulations using the global climate model LMDZ to explore the limits of
the mean flux approximation when varying the luminosity of the host star
and the eccentricity of the planet. We computed the climate of tidally
locked ocean covered planets with orbital eccentricity from 0 to 0.9
receiving a mean flux equal to Earth's. These planets are found around
stars of luminosity ranging from 1 L$_{&sun;}$ to
10$^{-4}$L$_{&sun;}$. We use a definition of habitability
based on the presence of surface liquid water, and find that most of the
planets considered can sustain surface liquid water on the dayside with
an ice cap on the nightside. However, for high eccentricity and high
luminosity, planets cannot sustain surface liquid water during the whole
orbital period. They completely freeze at apoastron and when approaching
periastron an ocean appears around the substellar point. We conclude
that the higher the eccentricity and the higher the luminosity of the
star, the less reliable the mean flux approximation.
}},
doi = {10.1051/0004-6361/201628073},
adsurl = {https://ui.adsabs.harvard.edu/abs/2016A%26A...591A.106B},
localpdf = {https://ui.adsabs.harvard.edu/abs/2016A_26A...591A.106B.pdf},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2014Icar..238..110G,
author = {{Guerlet}, S. and {Spiga}, A. and {Sylvestre}, M. and {Indurain}, M. and
{Fouchet}, T. and {Leconte}, J. and {Millour}, E. and {Wordsworth}, R. and
{Capderou}, M. and {Bézard}, B. and {Forget}, F.},
title = {{Global climate modeling of Saturn{\rsquo}s atmosphere. Part I: Evaluation of the radiative transfer model}},
journal = {\icarus},
year = 2014,
volume = 238,
pages = {110-124},
abstract = {{We have developed and optimized a seasonal, radiative-convective model
of Saturn{\rsquo}s upper troposphere and stratosphere. It is used to
investigate Saturn{\rsquo}s radiatively-forced thermal structure between
3 and 10$^{-6}$ bar, and is intended to be included in a Saturn
global climate model (GCM), currently under development. The main
elements of the radiative transfer model are detailed as well as the
sensitivity to spectroscopic parameters, hydrocarbon abundances, aerosol
properties, oblateness, and ring shadowing effects. The vertical
temperature structure and meridional seasonal contrasts obtained by the
model are then compared to Cassini/CIRS observations. Several
significant model-observation mismatches reveal that Saturn{\rsquo}s
atmosphere departs from radiative equilibrium. For instance, we find
that the modeled temperature profile is close to isothermal above the
2-mbar level, while the temperature retrieved from ground-based or
Cassini/CIRS data continues to increase with altitude. Also, no local
temperature minimum associated to the ring shadowing is observed in the
data, while the model predicts stratospheric temperatures 10 K to 20 K
cooler than in the absence of rings at winter tropical latitudes. These
anomalies are strong evidence that processes other that radiative
heating and cooling control Saturn{\rsquo}s stratospheric thermal
structure. Finally, the model is used to study the warm stratospheric
anomaly triggered after the 2010 Great White Spot. Comparison with
recent Cassini/CIRS observations suggests that the rapid cooling phase
of this warm {\ldquo}beacon{\rdquo} in May-June 2011 can be explained by
radiative processes alone. Observations on a longer timeline are needed
to better characterize and understand its long-term evolution.
}},
doi = {10.1016/j.icarus.2014.05.010},
adsurl = {https://ui.adsabs.harvard.edu/abs/2014Icar..238..110G},
localpdf = {https://ui.adsabs.harvard.edu/abs/2014Icar..238..110G.pdf},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2014RSPTA.37230084F,
author = {{Forget}, F. and {Leconte}, J.},
title = {{Possible climates on terrestrial exoplanets}},
journal = {Philosophical Transactions of the Royal Society of London Series A},
archiveprefix = {arXiv},
eprint = {1311.3101},
primaryclass = {astro-ph.EP},
year = 2014,
volume = 372,
pages = {20130084-20130084},
abstract = {{What kind of environment may exist on terrestrial planets around other
stars? In spite of the lack of direct observations, it may not be
premature to speculate on exoplanetary climates, for instance to
optimize future telescopic observations, or to assess the probability of
habitable worlds. To first order, climate primarily depends on 1) The
atmospheric composition and the volatile inventory; 2) The incident
stellar flux; 3) The tidal evolution of the planetary spin, which can
notably lock a planet with a permanent night side. The atmospheric
composition and mass depends on complex processes which are difficult to
model: origins of volatile, atmospheric escape, geochemistry,
photochemistry. We discuss physical constraints which can help us to
speculate on the possible type of atmosphere, depending on the planet
size, its final distance for its star and the star type. Assuming that
the atmosphere is known, the possible climates can be explored using
Global Climate Models analogous to the ones developed to simulate the
Earth as well as the other telluric atmospheres in the solar system. Our
experience with Mars, Titan and Venus suggests that realistic climate
simulators can be developed by combining components like a ``dynamical
core'', a radiative transfer solver, a parametrisation of subgrid-scale
turbulence and convection, a thermal ground model, and a volatile phase
change code. On this basis, we can aspire to build reliable climate
predictors for exoplanets. However, whatever the accuracy of the models,
predicting the actual climate regime on a specific planet will remain
challenging because climate systems are affected by strong positive
destabilizing feedbacks (such as runaway glaciations and runaway
greenhouse effect). They can drive planets with very similar forcing and
volatile inventory to completely different states.
}},
doi = {10.1098/rsta.2013.0084},
adsurl = {https://ui.adsabs.harvard.edu/abs/2014RSPTA.37230084F},
localpdf = {https://ui.adsabs.harvard.edu/abs/2014RSPTA.37230084F.pdf},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2013Natur.504..268L,
author = {{Leconte}, J. and {Forget}, F. and {Charnay}, B. and {Wordsworth}, R. and
{Pottier}, A.},
title = {{Increased insolation threshold for runaway greenhouse processes on Earth-like planets}},
journal = {\nat},
archiveprefix = {arXiv},
eprint = {1312.3337},
primaryclass = {astro-ph.EP},
year = 2013,
volume = 504,
pages = {268-271},
abstract = {{The increase in solar luminosity over geological timescales should warm
the Earth's climate, increasing water evaporation, which will in turn
enhance the atmospheric greenhouse effect. Above a certain critical
insolation, this destabilizing greenhouse feedback can `run away' until
the oceans have completely evaporated. Through increases in
stratospheric humidity, warming may also cause evaporative loss of the
oceans to space before the runaway greenhouse state occurs. The critical
insolation thresholds for these processes, however, remain uncertain
because they have so far been evaluated using one-dimensional models
that cannot account for the dynamical and cloud feedback effects that
are key stabilizing features of the Earth's climate. Here we use a
three-dimensional global climate model to show that the insolation
threshold for the runaway greenhouse state to occur is about 375 W
m$^{-2}$, which is significantly higher than previously thought.
Our model is specifically developed to quantify the climate response of
Earth-like planets to increased insolation in hot and extremely moist
atmospheres. In contrast with previous studies, we find that clouds have
a destabilizing feedback effect on the long-term warming. However,
subsident, unsaturated regions created by the Hadley circulation have a
stabilizing effect that is strong enough to shift the runaway greenhouse
limit to higher values of insolation than are inferred from
one-dimensional models. Furthermore, because of wavelength-dependent
radiative effects, the stratosphere remains sufficiently cold and dry to
hamper the escape of atmospheric water, even at large fluxes. This has
strong implications for the possibility of liquid water existing on
Venus early in its history, and extends the size of the habitable zone
around other stars.
}},
doi = {10.1038/nature12827},
adsurl = {https://ui.adsabs.harvard.edu/abs/2013Natur.504..268L},
localpdf = {https://ui.adsabs.harvard.edu/abs/2013Natur.504..268L.pdf},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2013JGRD..11810414C,
author = {{Charnay}, B. and {Forget}, F. and {Wordsworth}, R. and {Leconte}, J. and
{Millour}, E. and {Codron}, F. and {Spiga}, A.},
title = {{Exploring the faint young Sun problem and the possible climates of the Archean Earth with a 3-D GCM}},
journal = {Journal of Geophysical Research (Atmospheres)},
archiveprefix = {arXiv},
eprint = {1310.4286},
primaryclass = {astro-ph.EP},
keywords = {early Earth, Archean, paleo-climates},
year = 2013,
volume = 118,
number = d17,
pages = {10},
abstract = {{Different solutions have been proposed to solve the ``faint young Sun
problem,'' defined by the fact that the Earth was not fully frozen during
the Archean despite the fainter Sun. Most previous studies were
performed with simple 1-D radiative convective models and did not
account well for the clouds and ice-albedo feedback or the atmospheric
and oceanic transport of energy. We apply a global climate model (GCM)
to test the different solutions to the faint young Sun problem. We
explore the effect of greenhouse gases (CO$_{2}$ and
CH$_{4}$), atmospheric pressure, cloud droplet size, land
distribution, and Earth's rotation rate. We show that neglecting organic
haze, 100 mbar of CO$_{2}$ with 2 mbar of CH$_{4}$ at 3.8 Ga
and 10 mbar of CO$_{2}$ with 2 mbar of CH$_{4}$ at 2.5 Ga
allow a temperate climate (mean surface temperature between 10{\deg}C and
20{\deg}C). Such amounts of greenhouse gases remain consistent with the
geological data. Removing continents produces a warming lower than
+4{\deg}C. The effect of rotation rate is even more limited. Larger
droplets (radii of 17 {$\mu$}m versus 12 {$\mu$}m) and a doubling of the
atmospheric pressure produce a similar warming of around +7{\deg}C. In
our model, ice-free water belts can be maintained up to 25{\deg}N/S with
less than 1 mbar of CO$_{2}$ and no methane. An interesting cloud
feedback appears above cold oceans, stopping the glaciation. Such a
resistance against full glaciation tends to strongly mitigate the faint
young Sun problem.
}},
doi = {10.1002/jgrd.50808},
adsurl = {https://ui.adsabs.harvard.edu/abs/2013JGRD..11810414C},
localpdf = {https://ui.adsabs.harvard.edu/abs/2013JGRD..11810414C.pdf},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2013A&A...554A..69L,
author = {{Leconte}, J. and {Forget}, F. and {Charnay}, B. and {Wordsworth}, R. and
{Selsis}, F. and {Millour}, E. and {Spiga}, A.},
title = {{3D climate modeling of close-in land planets: Circulation patterns, climate moist bistability, and habitability}},
journal = {\aap},
archiveprefix = {arXiv},
eprint = {1303.7079},
primaryclass = {astro-ph.EP},
keywords = {planets and satellites: general, planets and satellites: atmospheres, planets and satellites: physical evolution, planet-star interactions},
year = 2013,
volume = 554,
eid = {A69},
pages = {A69},
abstract = {{The inner edge of the classical habitable zone is often defined by the
critical flux needed to trigger the runaway greenhouse instability. This
1D notion of a critical flux, however, may not be all that relevant for
inhomogeneously irradiated planets, or when the water content is limited
(land planets). Based on results from our 3D global climate model, we
present general features of the climate and large-scale circulation on
close-in terrestrial planets. We find that the circulation pattern can
shift from super-rotation to stellar/anti stellar circulation when the
equatorial Rossby deformation radius significantly exceeds the planetary
radius, changing the redistribution properties of the atmosphere. Using
analytical and numerical arguments, we also demonstrate the presence of
systematic biases among mean surface temperatures and among temperature
profiles predicted from either 1D or 3D simulations. After including a
complete modeling of the water cycle, we further demonstrate that two
stable climate regimes can exist for land planets closer than the inner
edge of the classical habitable zone. One is the classical runaway state
where all the water is vaporized, and the other is a collapsed state
where water is captured in permanent cold traps. We identify this
``moist'' bistability as the result of a competition between the
greenhouse effect of water vapor and its condensation on the night side
or near the poles, highlighting the dynamical nature of the runaway
greenhouse effect. We also present synthetic spectra showing the
observable signature of these two states. Taking the example of two
prototype planets in this regime, namely Gl 581 c and HD 85512 b, we
argue that depending on the rate of water delivery and atmospheric
escape during the life of these planets, they could accumulate a
significant amount of water ice at their surface. If such a thick ice
cap is present, various physical mechanisms observed on Earth (e.g.,
gravity driven ice flows, geothermal flux) should come into play to
produce long-lived liquid water at the edge and/or bottom of the ice
cap. Consequently, the habitability of planets at smaller orbital
distance than the inner edge of the classical habitable zone cannot be
ruled out. Transiting planets in this regime represent promising targets
for upcoming exoplanet characterization observatories, such as EChO and
JWST.
}},
doi = {10.1051/0004-6361/201321042},
adsurl = {https://ui.adsabs.harvard.edu/abs/2013A%26A...554A..69L},
localpdf = {https://ui.adsabs.harvard.edu/abs/2013A_26A...554A..69L.pdf},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}