TRAPPIST Habitable Atmosphere Intercomparison (THAI) Workshop


Context of the workshop: Upcoming telescopes such as the James Webb Space Telescope (JWST), or Extremely Large Telescope (ELTs) may soon be able to characterize the atmospheres of rocky exoplanets orbiting nearby M dwarfs. TRAPPIST-1e seems to be one of the most promising candidate to have potentially habitable surface conditions and is therefore one of the prime targets for JWST atmospheric characterization.

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 predictions and thus different observability of atmospheric features in the spectra. Such differences should preferably be known prior to observations in order to have more accurate observational constraints and to reduce model dependency while interpret the data (see the TRAPPIST-1 JWST initiative

The TRAPPIST Habitable Atmosphere Intercomparison (THAI) have recently allowed to compare the atmospheric outputs obtained from four planetary GCMs: ExoCAM, LMD-G, ROCKE-3D and UM and their associated spectral simulations produced by the Planetary Spectrum Generator (PSG). The protocol of this intermodel comparison is available here:

Objective of the workshop: The objective of this workshop is to use THAI as a vector for comparisons and discussions between GCMs use in Exoplanetary Science to predict the climate of rocky exoplanets in the Habitable Zone, the detectability of their atmosphere (if any) and their characterization. Other Model Intercomparisons will be discussed such as the one initiated in 2019 by Jun Yang for planets at the inner edge of the Habitable Zone of M dwarfs and even the Coupled Model Intercomparison Project (CMIP), currently in its version 6, running for decades to evaluate differences in GCM responses to forcings for anthropogenic climate change on Earth. We are particularly looking for to welcome other GCM groups and users than the one currently onboard THAI, to join the discussion and contribute to the intermodel comparison and to this workshop. Along with the GCMs, Energy Balance Models (EBMs) and 1D models would also be discussed and compared within the THAI framework.

The parameterizations of convection clouds will have a central part of the discussions as they are expected to be the largest source of discrepancy between the models and that they produce a strong impact on the planetary spectra. Discussions will include -but are not limited to- the following questions:

  • What can we learn from the ongoing CMIP (members from CMIP will be present to share their experience)?
  • What did we learn from the THAI intermodel comparison effort?
  • Synergy between 3-D models and other models (1-D, EBM, Cloud Resolving Models (CRMs))?
  • What are the goals and methods that an expansion of this intermodel comparison community should adopt?

This workshop would be the first opportunity to get together many exoplanet GCM experts from different teams to discuss the important questions to tackle and the future of the field.

Few invited talks will drive the discussions around the above questions but a lot of time will be dedicated to open discussions.

Code of Conduct

The organizers are committed to making this meeting productive and enjoyable for everyone, regardless of gender, sexual orientation, disability, physical appearance, body size, race, nationality or religion. We will not tolerate harassment of participants in any form. Please follow these guidelines:

Behave professionally. Harassment and sexist, racist, or exclusionary comments or jokes are not appropriate. Harassment includes sustained disruption of talks or other events, inappropriate physical contact, sexual attention or innuendo, deliberate intimidation, stalking, and photography or recording of an individual without consent. It also includes offensive comments related to gender, sexual orientation, disability, physical appearance, body size, race or religion.
All communication should be appropriate for a professional audience including people of many different backgrounds. Sexual language and imagery is not appropriate.
Be kind to others. Do not insult or put down other attendees.
Participants asked to stop any inappropriate behaviour are expected to comply immediately. Attendees violating these rules may be asked to leave the event at the sole discretion of the organizers without a refund of any charge.
Any participant who wishes to report a violation of this policy is asked to speak, in confidence, to Thomas Fauchez (thomas.j.fauchez -at- or Shawn Domagal Goldman (shawn.goldman -at-

This code of conduct is based on the “London Code of Conduct“, as originally designed for the conference “Accurate Astrophysics. Correct Cosmology”, held in London in July 2015. The London Code of Conduct was adapted with permission by Andrew Pontzen and Hiranya Peiris from a document by Software Carpentry](, which itself derives from original Creative Commons documents by PyCon and Geek Feminism. It is released under a CC-Zero licence for reuse. To help track people’s improvements and best practice, please retain this acknowledgement, and log your re-use or modification of this policy at


The conference web interface will open on September 4th, registration will close on September 14th . The workshop will be held virtually on Zoom over the course of three days, between September 14th to 16th, for three hours per day (8am to 11am CDT). Contrary to a conference workshop, we will focus exclusively on live discussions and breakouts in order to produce dynamic interactions between the participants.

Each live session will start with 1 minute lightning talks from the invited speakers following by about 1 hour of Q&A. After a short break, we will have 1-1.5 hours of break-out discussions.

One of the objectives of this workshop is to write a workshop report that summarizes the talks, live discussions, and breakouts. We intend for the community to use this as a reference document for the development of GCMs for exoplanet studies.

To receive more info about the THAI workshop please contact Thomas Fauchez, at

Scientific Organizing Committee (SOC):
Thomas J. Fauchez (USRA / GSFC contractor)
Shawn Domagal-Goldman (NASA GSFC)
Ravi Kumar Kopparapu(NASA GSFC)
Linda Sohl (Columbia University)
Martin Turbet (Geneva Observatory, Switzerland)
Michael J. Way (NASA GISS)
Eric T. Wolf (Colorado University)