software-oasis

OASIS

OASIS is a novel theoretical framework to determine the key physical processes driving the diversity of planetary environments, and to determine the effects of biological activity in these environments. This work will also explore scenarios where non-biological processes could mislead the interpretation of observational data in the search for life.

OASIS is being gradually improved in terms of code performance, usability and complexity in the physical modules. 

THOR

THOR is a global circulation model that solves the three-dimensional non-hydrostatic Euler equations on an icosahedral grid (Mendonca et al. 2016). THOR is still the only model in the planetary community that has been developed from ground-up with the purpose of exploring a large diversity of planets and avoiding physical approximations brought from other research fields, such as, the Earth climate research. This model has the capacity to simulate virtual atmospheres by coupling the physics self-consistently.

CYCLOPS

CYCLOPS is a fast radiative parameterization that represents the absorption/emission/scattering by gases and clouds (Mendonca et al. 2015). The stellar radiation  calculations are based on the δ-Eddington approximation (two-stream-type) with an adding layer method (multiple-scattering). For the thermal radiation case, the code is based on an absorptivity/emissivity formulation. The formulation is implemented on GPUs and it is intended to be computationally light. This code allow us to investigate the dynamical-radiative-microphysical feedbacks on 3D simulations. The simulations typically use 353 spectral bands and 20 Gaussian points ( k-distribution).

STORM

STORM is the physics module in OASIS that represents the cloud physics. The current version is based on a radiative active tracer coupled with a cloud condensation parameterisation explored in Mendonca (2013).

ATLANTIS

ATLANTIS represents the oceans, surface and interior of planets. Currently the scheme includes: a simple Rayleigh friction to represent the mechanical interaction between the surface and the atmosphere; a coloured surface where the optical properties of the surface can be easily modified and a soil model that simulates the evolution of the temperatures in the subsurface (Mendonca & Read 2016).

LOKI

LOKI represents the small-scale turbulence in the atmosphere. Physics that happens in scales smaller than the spatial resolution of the model need to be parametrized. We include a hyper-diffusion coupled with a divergence damping scheme to represent the dissipation of kinetic energy to smaller scales. The convection is currently done with a convective adjustment scheme where the potential temperature is vertically mixed in a buoyantly unstable atmospheric column.

MERLIN

MERLIN is the atmospheric chemistry module in OASIS. MERLIN represents the chemistry in the atmosphere, surface and interior (including vulcanic outgassing).  At the moment, we can run simulations with the atmosphere in chemical equilibrium, use the relaxation method described in Tsai et al (2018) or set manually the chemical abundances in the atmosphere and surface.

GAIA

GAIA is an OASIS module that is still under-construction. This package will represent the impact of biology in planetary climates.

FIRST TEST

OASIS is currently being tested on Venus. Simulations of the Venus climate are technically challenging and this work will allow us to identify the mechanisms driving the climate and circulation in the planet, and validate the robustness of the model (Mendonca 2018). The tests are being performed using all the physical modules described above.

REFERENCES

Mendonca J., Buchhave L., ‘The temperature and winds of Venus modelled by OASIS‘, in preparation

Tsai S., Kitzmann D., Lyons J., Mendonca J.,  Grimm S., Heng K., ‘Towards Consistent Modeling of Atmospheric Chemistry and Dynamics in Exoplanets: Validation and Generalization of Chemical Relaxation Method’, 2017, in press, The Astrophysical Journal [Link]

Mendonca J. and Read P., ‘Exploring the Venus global super-rotation using a comprehensive Global Circulation Model’, 2016, Volume 134, pp 1-18, Planetary and Space Sciences. [Link]

Mendonca J., Grimm S., Grosheintz L., Heng K., ‘THOR: A New and Flexible Global Circulation Model to Explore Planetary Atmospheres’, 2016, Volume 829, Issue 2, The Astrophysical Journal. [Link]

Mendonca J., Read P., Wilson C., Lee C., ‘A new, fast and flexible radiative transfer method for Venus general circulation models’, 2015, Volume 105, p. 80-93., Planetary and Space Science. [Link]

Mendonca J., ‘Studies of Venus using a comprehensive General Circulation Model. Ph.D’, 2013, thesis, Oxford University