Maxence Lefevre | Searcharxiv

arXiv2024

Venus

After decades of relative neglect, interest in Venus surges anew in the planetary science community and the public. New missions are planned and selected, and will pave the way to the decade of Venus, as new observations allow us to uncover some of the many mysteries our closest Solar System neighbor still harbors. Building on the legacy of past works, here, we discuss the state of our understanding of Venus, from both observation and modeling. We describe each of the envelopes of the planet, from its atmosphere to its interior with an eye for the most recent advances and current topics of interest. We then briefly discuss coupled modelling efforts to better constrain the evolution of the planet. Finally, we describe how the upcoming missions and concepts will further lift the veil on Venus' secrets.

astro-ph.EP↗

arXiv2021

Convection modeling of pure-steam atmospheres

Condensable species are crucial in shaping planetary climate. A wide range of planetary climate systems involve understanding non-dilute condensable substances and their influence on climate dynamics. There has been progress on large-scale dynamical effects and on 1D convection parameterization, but resolved 3D moist convection remains unexplored in non-dilute conditions, though it can have a profound impact on temperature/humidity profiles and cloud structure. We tackle this problem for pure-steam atmospheres using three-dimensional, high-resolution numerical simulations of convection in post-runaway atmospheres where the water reservoir at the surface has been exhausted. We show that the atmosphere is comprised of two characteristic regions, an upper condensing region dominated by gravity waves and a lower noncondensing region characterized by convective overturning cells. Velocities in the condensing region are much smaller than those in the lower noncondensing region, and the horizontal temperature variation is small overall. Condensation in the thermal photosphere is largely driven by radiative cooling and tends to be statistically homogeneous. Some condensation also happens deeper, near the boundary of the condensing region, due to triggering by gravity waves and convective penetrations and exhibit random patchiness. This qualitative structure is insensitive to varying model parameters, but quantitative details may differ. Our results confirm theoretical expectations that atmospheres close to the pure-steam limit do not have organized deep convective plumes in the condensing region. The generalized convective parameterization scheme discussed in Ding & Pierrehumbert (2016) is appropriate to handle the basic structure of atmospheres near the pure-steam limit but is difficult to capture gravity waves and their mixing that appear in 3D convection-resolving models.

astro-ph.EP↗

arXiv2021

TRAPPIST Habitable Atmosphere Intercomparison (THAI) workshop report

The era of atmospheric characterization of terrestrial exoplanets is just around the corner. Modeling prior to observations is crucial in order to predict the observational challenges and to prepare for the data interpretation. This paper presents the report of the TRAPPIST Habitable Atmosphere Intercomparison (THAI) workshop (14-16 September 2020). A review of the climate models and parameterizations of the atmospheric processes on terrestrial exoplanets, model advancements and limitations, as well as direction for future model development was discussed. We hope that this report will be used as a roadmap for future numerical simulations of exoplanet atmospheres and maintaining strong connections to the astronomical community.

astro-ph.EP↗