An international team, including astrophysicists from the University of Exeter, has taken lessons and techniques learned from earth climate science to pave the way for reliably modeling the atmospheres of planets orbiting distant stars, potentially habitable. We support the search for exoplanets.

Importantly, the team believes the research can also strengthen our fundamental understanding and projections of future climate on our planet.

The recently launched James Webb Space Telescope (JWST) and future telescopes such as the European Very Large Telescope (E-ELT), the 30 Meter Telescope (TMT) and the Giant Magellan Telescope (GMT) will soon characterize the Earth’s atmosphere. may be possible. A rocky exoplanet orbiting a nearby red dwarf (a star that is cooler and smaller than our own Sun). However, the full potential of these observatories cannot be realized without robust models to interpret and guide these observations.

One way is to use a 3D general circulation model (GCM). This simulates the atmospheric characteristics of a planet as it orbits its star, similar to models used to predict Earth’s climate. However, essential differences exist within these complex GCMs, leading to contrasting climate predictions and, consequently, interpretation of exoplanet observations.

In recent years, scientists have refined GCMs to replicate and understand current warming trends associated with global human-induced climate change. The main approach is to model climate with multiple GCMs and contrast them via the Model Intercomparison Project (MIP). This is the basis of our knowledge of the Earth’s climate.

A team led by three early career researchers, Thomas Fauchez (NASA GSFC, American University, USA), Denis Sergeev (University of Exeter, UK), and Martin Turbet (LMD, France), has combined this expertise with the recent model Comprehensive inter-comparison of several world-leading GCMs applied to exoplanet studies, using upgrades from .

Dr Sergeev, a postdoctoral researcher at the University of Exeter, said: Incorporating these comparisons into the study of exoplanets could ultimately improve our ability to interpret telescope observations. ”

A pivotal new project called THAI (TRAPPIST-1 Habitable Atmosphere Intercomparison) focuses on a confirmed Earth-sized exoplanet labeled TRAPPIST-1e. It is her fourth planet from its main star, the red dwarf TRAPPIST-1, about 40 light-years from Earth. Importantly, the planet’s orbit lies within her TRAPPIST-1’s habitable zone, so it may have a temperate climate suitable for the presence of liquid water on its surface.

This project is based on four widely used models: ExoCAM (based on the US National Center for Atmospheric Research model), LMD-G (developed by the Laboratoire de Meterologie Dynamique, Paris), and ROCKE-3D (based on the NASA GISS model). based on). ) and UM (developed at the UK Meteorological Office and adapted to exoplanets by researchers at the University of Exeter)- TRAPPIST-1e considers his four different scenarios for the atmosphere.

These are two scenarios for the surface (completely dry and covered by a global ocean that provides moisture to the atmosphere) and two scenarios for atmospheric composition (a nitrogen-rich atmosphere with modern global levels of CO2). ) consisted of₂or Mars-like CO₂-dominant atmosphere).

Clouds are one of the biggest sources of differences between GCMs. Their optical properties, altitude, thickness and extent have been shown to vary significantly between models due to differences in cloud parameterization. “Representing small-scale wetness physics in the GCM is notoriously difficult. It is one of the main tools of atmospheric research, both for exoplanets and for Earth climate science.” Dr. Sergeev said.

Dr. Fauchez, who leads the THAI project, said: A framework developed as part of the Exoplanets application. ”

The results of these analyzes, including for the first time showing how the use of GCMs influence future data interpretation and future planning of observational campaigns, are presented in three fully open-access articles. Full results will be published in a special issue on September 15, 2022. Planetary Science Journal (PSJ).

But the team not only paves the way for THAI to robustly model potentially habitable distant worlds, but also aligns our efforts to find extraterrestrial life in our own changing climate. I believe it has something to do with research.

Dr. Sergeev adds:

THAI paves the way for a larger model intercomparison project, Climate Using a Nested Intercomparison Suite for Exoplanet Studies (CUISINES). This project includes a wide variety of exoplanet targets and models to systematically compare and validate.