THOR's Martian war: testing a new GCM's ability to model Mars's atmosphere

Observations of planets within and beyond our solar system have highlighted a diverse range of planetary climates that Earth-centric and Earth-derived General Circulation Models (GCMs) are unlikely to be suited to. A self-consistent GCM, capable of adapting to a wide range of planetary conditions without compromising accuracy, is therefore needed. A new GCM called THOR may fill this void. THOR, an atmospheric fluid dynamics solver optimized for GPU computation, was developed from first principles and lacks the assumptions of Earth-derived GCMs. Its performance has been tested with the Martian atmosphere using fundamental planetary and orbital properties with a basic radiative transfer scheme, although topography has not been included. Through this, the influence of optical depth and obliquity on zonally-averaged temperature, zonal winds, and vertical velocity has been investigated. A key finding is that dust has a first-order effect and is particularly important at higher obliquities. Results were compared extensively against previous studies of Mars which had made use of existing GCMs for simulations. These results indicate that THOR's dynamics perform reasonably well but confirm its high sensitivity to dust loading. Future improvements to THOR's treatment of dust and aerosols could make THOR quite suitable for simulation with dusty planets.