The project has substantially advanced the understanding of the behaviour of condensible substances in exoplanet atmospheres, and laid the groundwork for interpretation of data from observations with the James Webb Space telescope. Accomplishments have been in two general areas: global circulation models of exoplanet atmospheres, and regional scale simulations of three dimensional convection involving condensation and clouds. Dissemination has been in the form of journal articles, doctoral dissertations, presentations at domestic and international meetings, and publicly available model code. A few highlights of these results are presented below:
- A series of journal articles concerning basic aspects of exoplanet dynamics which provide the underpinning for understanding condensation processes, drawing on concepts in linear wave dynamics that were originally developed for understanding the Earth's tropical circulation, especially phenomena such as El Nino.
- The first simulation of the lava planet 55 Cancri-e which took into account the possibility of a non-condensible background atmosphere, which appears to be necessary to explain the relatively warm night-side temperatures of the planet.
- The first simulation of the global circulation of a brown dwarf star in orbit around and irradiated by a host star. Brown dwarfs are an outstanding and highly observable laboratory for probing the effects of clouds and condensation. The EXOCONDENSE team has published additional work probing condensation behaviour on such objects, employing our generalized version of the CM1 three dimensional convection model. The same model has been used for the first simulation of convection in pure steam atmospheres.
- Produced the first model of the outer edge of the habitable zone to incorporate modern advances in the understanding of geochemical weathering processes. This work has considerable bearing on the interpretation of observations which seek the signature of a chemical-weathering thermostat in action. .
-Developed simulations of subNeptune exoplanets, with particular application to the exoplanet K2-18b. subNeptunes are low-density planets bigger than Earth and smaller than Neptune, having an extensive fluid envelope compared to Earth's atmosphere and ocean. These results include the first incorporation of stabilization of the atmosphere against convection by the presence of a water-rich layer in a Hydrogen atmosphere, and delineate the circumstances under which a liquid water ocean can exist. An additional article on subNeptunes described how the runaway greenhouse phenomenon affects the interior structure of the planet.
-Developed one dimensional and three dimensional models of post-runaway pure steam atmospheres, applying them to elucidate the fate of planets that have undergone a runaway greenhouse process.
-Used convection-resolving simulations to simulate 3D convection in planetary atmospheres in which the buoyancy is affected strongly by gradients in composition (e.g the hydrogen to water vapour ratio).
