•A new 3D Global Climate Model (GCM) to simulate Pluto’s atmosphere is described.•The model simulates temperatures, winds and the N2, CH4 and CO cycles.•Surface winds are induced by the topography ...and N2 condensation and sublimation.•A cold atmospheric layer is obtained in Sputnik Planum, as observed by New Horizons.•The GCM predicts abundance of CO and CH4 gas in agreement with observations.
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 N2, CH2 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 N2 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 N2 daytime sublimation. In the reference simulation with surface N2 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 N2 condensation and sublimation around Sputnik Planum. However, the circulation can be more intense depending on the exact distribution of surface N2 frost. This is illustrated in an alternative simulation with N2 condensing in the South Polar regions and N2 frost covering latitudes between 35°N and 48°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 CH4 in good agreement with the observations. N2 and CO do not condense in the atmosphere, but CH4 ice clouds can form during daytime at low altitude near the regions covered by N2 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).
► Global 3D study of the early martian climate and water cycle. ► New general circulation model with accurate radiative transfer and dynamic clouds developed. ► Simulations show adiabatic effect at ...higher CO2 pressure causes ice to migrate to valley network regions. ► Seasonal melting insufficient to explain necessary erosion. ► Impacts, volcanism or basal melting may have caused episodic flooding events.
We discuss 3D global simulations of the early martian climate that we have performed assuming a faint young Sun and denser CO2 atmosphere. We include a self-consistent representation of the water cycle, with atmosphere–surface interactions, atmospheric transport, and the radiative effects of CO2 and H2O gas and clouds taken into account. We find that for atmospheric pressures greater than a fraction of a bar, the adiabatic cooling effect causes temperatures in the southern highland valley network regions to fall significantly below the global average. Long-term climate evolution simulations indicate that in these circumstances, water ice is transported to the highlands from low-lying regions for a wide range of orbital obliquities, regardless of the extent of the Tharsis bulge. In addition, an extended water ice cap forms on the southern pole, approximately corresponding to the location of the Noachian/Hesperian era Dorsa Argentea Formation. Even for a multiple-bar CO2 atmosphere, conditions are too cold to allow long-term surface liquid water. Limited melting occurs on warm summer days in some locations, but only for surface albedo and thermal inertia conditions that may be unrealistic for water ice. Nonetheless, meteorite impacts and volcanism could potentially cause intense episodic melting under such conditions. Because ice migration to higher altitudes is a robust mechanism for recharging highland water sources after such events, we suggest that this globally sub-zero, ‘icy highlands’ scenario for the late Noachian climate may be sufficient to explain most of the fluvial geology without the need to invoke additional long-term warming mechanisms or an early warm, wet Mars.
► We present 3D simulations of the possible early Mars climate. ► We assume a faint young Sun and a thick CO2 atmosphere with CO2 clouds. ► We explore various obliquities, orbits, cloud parameters ...and dust loading. ► The mean temperature cannot be raised above 0°C anywhere on the planet.
On the basis of geological evidence, it is often stated that the early martian climate was warm enough for liquid water to flow on the surface thanks to the greenhouse effect of a thick atmosphere. We present 3D global climate simulations of the early martian climate performed assuming a faint young Sun and a CO2 atmosphere with surface pressure between 0.1 and 7bars. The model includes a detailed radiative transfer model using revised CO2 gas collision induced absorption properties, and a parameterisation of the CO2 ice cloud microphysical and radiative properties. A wide range of possible climates is explored using various values of obliquities, orbital parameters, cloud microphysic parameters, atmospheric dust loading, and surface properties.
Unlike on present day Mars, for pressures higher than a fraction of a bar, surface temperatures vary with altitude because of the adiabatic cooling and warming of the atmosphere when it moves vertically. In most simulations, CO2 ice clouds cover a major part of the planet. Previous studies had suggested that they could have warmed the planet thanks to their scattering greenhouse effect. However, even assuming parameters that maximize this effect, it does not exceed +15K. Combined with the revised CO2 spectroscopy and the impact of surface CO2 ice on the planetary albedo, we find that a CO2 atmosphere could not have raised the annual mean temperature above 0°C anywhere on the planet. The collapse of the atmosphere into permanent CO2 ice caps is predicted for pressures higher than 3bar, or conversely at pressure lower than 1bar if the obliquity is low enough. Summertime diurnal mean surface temperatures above 0°C (a condition which could have allowed rivers and lakes to form) are predicted for obliquity larger than 40° at high latitudes but not in locations where most valley networks or layered sedimentary units are observed. In the absence of other warming mechanisms, our climate model results are thus consistent with a cold early Mars scenario in which nonclimatic mechanisms must occur to explain the evidence for liquid water. In a companion paper by Wordsworth et al. we simulate the hydrological cycle on such a planet and discuss how this could have happened in more detail.
The Europlanet-2020 programme, which ended on Aug 31 st , 2019, included an activity called VESPA (Virtual European Solar and Planetary Access), which focused on adapting Virtual Observatory (VO) ...techniques to handle Planetary Science data. This paper describes some aspects of VESPA at the end of this 4-years development phase and at the onset of the newly selected Europlanet-2024 programme starting in 2020. The main objectives of VESPA are to facilitate searches both in big archives and in small databases, to enable data analysis by providing simple data access and online visualization functions, and to allow research teams to publish derived data in an interoperable environment as easily as possible. VESPA encompasses a wide scope, including surfaces, atmospheres, magnetospheres and planetary plasmas, small bodies, helio-physics, exoplanets, and spectroscopy in solid phase. This system relies in particular on standards and tools developed for the Astronomy VO (IVOA) and extends them where required to handle specificities of Solar System studies. It also aims at making the VO compatible with tools and protocols developed in different contexts, for instance GIS for planetary surfaces, or time series tools for plasma-related measurements. An essential part of the activity is to publish a significant amount of high-quality data in this system, with a focus on derived products resulting from data analysis or simulations.
We use the Martian surface temperature response to Phobos transits observed next to the InSight lander in Elysium Planitia to constrain the thermal properties of the uppermost layer of regolith. ...Modeled transit lightcurves validated by solar panel current measurements are used to modify the boundary conditions of a 1D heat conduction model. We test several model parameter sets, varying the thickness and thermal conductivity of the top layer to explore the range of parameters that match the observed temperature response within its uncertainty both during the eclipse as well as the full diurnal cycle. The measurements indicate a thermal inertia (TI) of 103−16+22Jm−2K−1s−1/2 in the uppermost layer of 0.2–4 mm, significantly smaller than the TI of 200Jm−2K−1s−1/2 derived from the diurnal temperature curve. This could be explained by larger particles, higher density, or some or slightly higher amount of cementation in the lower layers.
Plain Language Summary
The Mars moon Phobos passed in front of the Sun from the perspective of the InSight lander on several occasions. The Mars surface temperatures measured by the lander became slightly colder during these transits due to the lower amount of sunlight the surface received at this time. The transits only last 20–35 s and therefore only the very top layer, about 0.3–0.8 mm, of the ground has time to cool significantly. The top layer cools and heats up faster than we expected based on the temperature changes of the day‐night cycle, which affects about 4 cm of the ground. Based on this observation we conclude that the material in the top mm of the ground is different from that below. A possible explanation would be an increase of density with depth, a larger fraction of smaller particles such as dust at the top, or a layer where particles are slightly cemented together beginning at 0.2–4 mm below the surface.
Key Points
The Martian surface temperature response to Phobos transits at the InSight landing site is interpreted
The thermal inertia of the uppermost layer of soil is 103−16+22Jm−2K−1s−1/2
The thermal conductivity or density of the top 0.2–4 mm is significantly less than that of the top 4 cm
Context.
The detection of sulphur species in the Martian atmosphere would be a strong indicator of volcanic outgassing from the surface of Mars.
Aims.
We wish to establish the presence of SO
2
, H
2
...S, or OCS in the Martian atmosphere or determine upper limits on their concentration in the absence of a detection.
Methods.
We perform a comprehensive analysis of solar occultation data from the mid-infrared channel of the Atmospheric Chemistry Suite instrument, on board the ExoMars Trace Gas Orbiter, obtained during Martian years 34 and 35.
Results.
For the most optimal sensitivity conditions, we determine 1
σ
upper limits of SO
2
at 20 ppbv, H
2
S at 15 ppbv, and OCS at 0.4 ppbv; the last value is lower than any previous upper limits imposed on OCS in the literature. We find no evidence of any of these species above a 3
σ
confidence threshold. We therefore infer that passive volcanic outgassing of SO
2
must be below 2 ktons day
−1
.
Water Supersaturation for Early Mars Delavois, A.; Forget, F.; Turbet, M. ...
Journal of geophysical research. Planets,
07/2023, Letnik:
128, Številka:
7
Journal Article
Recenzirano
Odprti dostop
We simulated water supersaturation in an Early Mars climate considering an abundant source of water on the surface and an arid scenarios; • Supersaturation can warm Early Mars only with unrealistic ...supersaturation ratios; • Supersaturation is only efficient when it occurs in the lower layers of the atmosphere in our simulations.
Neptune's moon Triton shares many similarities with Pluto, including volatile cycles of N2, CH4 and CO, and represents a benchmark case for the study of surface-atmosphere interactions on ...volatile-rich Kuiper Belt objects. The observations of Pluto by New Horizons acquired during the 2015 flyby and their analysis with volatile transport models (VTMs) shed light on how volatile sublimation-condensation cycles control the climate and shape the surface of such objects. Within the context of New Horizons observations as well as recent Earth-based observations of Triton, we adapt a Plutonian VTM to Triton, and test its ability to simulate its volatile cycles, thereby aiding our understanding of its climate.
Here we present numerical VTM simulations exploring the volatile cycles of N2, CH4 and CO on Triton over long-term and seasonal timescales (cap extent, surface temperatures, surface pressure, sublimation rates) for varying model parameters (including the surface ice reservoir, albedo, thermal inertia, and the internal heat flux). We explore what scenarios and model parameters allow for a best match of the available observations. In particular, our set of observational constraints include Voyager 2 observations (surface pressure and cap extent), ground-based near-infrared (0.8–2.4 μm) disk-integrated spectra (the relative surface area of volatile vs. non-volatile ice) and the evolution of surface pressure as retrieved from stellar occultations.
Our results show that Triton's poles act as cold traps for volatile ices and favor the formation of polar caps extending to lower latitudes through glacial flow or through the formation of thinner seasonal deposits. As previously evidenced by other VTMs, North-South asymmetries in surface properties can favor the development of one cap over the other. Our best-case simulations are obtained for a bedrock surface albedo of 0.6–0.7, a global reservoir of N2 ice thicker than 200 m, and a bedrock thermal inertia larger than 500 SI (or smaller but with a large internal heat flux). The large N2 ice reservoir implies a permanent N2 southern cap (several 100 m thick) extending to the equatorial regions with higher amounts of volatile ice at the south pole, which is not inconsistent with Voyager 2 images but does not fit well with observed full-disk near-infrared spectra. Our results also suggest that a small permanent polar cap exists in the northern (currently winter) hemisphere if the internal heat flux remains relatively low (e.g. radiogenic, < 3 mW m−2). A non-permanent northern polar cap was only obtained in some of our simulations with high internal heat flux (30 mW m−2). The northern cap will possibly extend to 30°N in the next decade, thus becoming visible by Earth-based telescopes. On the basis of our model results, we also discuss the composition of several surface units seen by Voyager 2 in 1989, including the bright equatorial fringe and dark surface patches.
Finally, we provide predictions for the evolution of ice distribution, surface pressure and CO and CH4 atmospheric mixing ratios in the next decades. According to our model, the surface pressure should slowly decrease but remain larger than 0.5 Pa by 2060. We also model the thermal lightcurves of Triton for different climate scenarios in 2022, which serve as predictions for future James Webb Space Telescope observations.
•Results suggest large global N2 reservoir (>200 m) and thermal inertia (>500 SI or smaller if internal heat flux >30 mW m−2).•Results suggest a permanent N2 southern cap (100 m to 1.5 km thick) extending to the equator with max. thickness at the pole.•Results suggest a small permanent polar cap should exist in the northern hemisphere, and could extend to 30°N by 2030.•Modeled surface pressures are consistent with a moderate increase of pressure during the 1990-2000 period.•JWST/MIRI will help in discriminating climate scenarios and in providing constraints on thermal/energetic surface properties.
The VESPA data access system focuses on applying Virtual Observatory (VO) standards and tools to Planetary Science. Building on a previous EC-funded Europlanet program, it has reached maturity during ...the first year of a new Europlanet 2020 program (started in 2015 for 4 years). The infrastructure has been upgraded to handle many fields of Solar System studies, with a focus both on users and data providers. This paper describes the broad lines of the current VESPA infrastructure as seen by a potential user, and provides examples of real use cases in several thematic areas. These use cases are also intended to identify hints for future developments and adaptations of VO tools to Planetary Science.
•VESPA distributes and searches data related to Solar System studies according to the Virtual Observatory (VO) paradigm.•The current status of the VESPA is described:•Uses case are presented to illustrate the usage of the search interface and tools.
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