TRAPPIST-1 Habitable Atmosphere Intercomparison (THAI). Motivations and protocol version 1.0

Abstract

Upcoming telescopes such as the James Webb Space Telescope (JWST), or the Extremely Large Telescope (ELTs), may soon be able to characterize, through transmission, emission or reflection spectroscopy, the atmospheres of rocky exoplanets orbiting nearby M dwarfs. One of the most promising candidates is the late M dwarf system TRAPPIST-1 which has seven known transiting planets for which Transit Timing Variation (TTV) measurements suggest that they are terrestrial in nature, with a possible enrichment in volatiles. Among these seven planets, TRAPPIST-1e seems to be the most promising candidate to have habitable surface conditions, receiving ~66 % of the Earth's incident radiation, and thus needing only modest greenhouse gas inventories to raise surface temperatures to allow surface liquid water to exist. TRAPPIST-1e is therefore one of the prime targets for JWST atmospheric characterization. In this context, the modeling of its potential atmosphere is an essential step prior to observation. Global Climate Models (GCMs) offer the most detailed way to simulate planetary atmospheres. However, intrinsic differences exist between GCMs which can lead to different climate prediction and thus observability of gas and/or cloud features in transmission and thermal emission spectra. Such differences should preferably be known prior to observations. In this paper we present a protocol to inter-compare planetary GCMs. Four testing cases are considered for TRAPPIST-1e but the methodology is applicable to other rocky exoplanets in the Habitable Zone. The four test cases included two land planets composed with a modern Earth and pure CO2 atmospheres, respectively, and two aqua planets with the same atmospheric compositions. Currently, there are four participating models (LMDG, ROCKE-3D, ExoCAM, UM), however this protocol is intended to let other teams participate as well.

Accepted and published in Geoscientific Model Development (GMD)

References in corpus (6)

• Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
• Strong Dependence of the Inner Edge of the Habitable Zone on Planetary Rotation Rate
• Observing the Atmospheres of Known Temperate Earth-sized Planets with JWST
• Impact of Clouds and Hazes on the Simulated JWST Transmission Spectra of Habitable Zone Planets in the TRAPPIST-1 System
• Temporal evolution of the high-energy irradiation and water content of TRAPPIST-1 exoplanets
• Simulations of Water Vapor and Clouds on Rapidly Rotating and Tidally Locked Planets: a 3D Model Intercomparison

Cited by in corpus (9)

• Atmospheric Regimes and Trends on Exoplanets and Brown Dwarfs
• A review of possible planetary atmospheres in the TRAPPIST-1 system
• Atmospheric convection plays a key role in the climate of tidally-locked terrestrial exoplanets: insights from high-resolution simulations
• Mineral dust increases the habitability of terrestrial planets but confounds biomarker detection
• Detectability of Chlorofluorocarbons in the Atmospheres of Habitable M-dwarf Planets
• Implications of different stellar spectra for the climate of tidally-locked Earth-like exoplanets
• How does Background Air Pressure Influence the Inner Edge of the Habitable Zone for Tidally Locked Planets in a 3D View?
• Small Sensitivity of the Simulated Climate of Tidally Locked Aquaplanets to Model Resolution
• Phase Modeling of the TRAPPIST-1 Planetary Atmospheres