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CESM-Planets is a natural progression of the Community Earth System Modeling framework to enable the study of planetary environments. The initial development is focused on enhancing the functionality of the Community Atmosphere Model (CAM) to run in simplified setup on Mars.
Using a baby steps approach, we begin by leveraging the CAM simple model framework to run an analytic Mars case based on Held-Suarez (HS). The case has been reconfigured to use standard Mars orbital characteristics and environmental conditions. An analytic initial condition is then run using the spectral elements dynamics core (ne16 resolution) along with a simple relaxation of the temperature field to an equilibrium state and applying a simple linear drag at the lower boundary. The initial vertical temperature structure and equilibrium relaxation state were created using results from the LMD-Mars model.
The relaxation to an equilibrium temperature is done in lieu of having actual Mars physics parameterizations to work with. The simple HS model allows us to exercise the dycore in the presence of realistic physics tendencies and provides a testing framework to diagnose and debug issues and determine how best to configure the dycore to run stably under Mars environmental conditions. To date we have demonstrated that the spectral element dycore is capable of running stably when starting from a Mars analytic initial condition. Additionally, a more balanced initial state has been produced from the end of a long-running HS experiment.
This initial HS test case will be used to add more fidelity to the modeled simulation with a stepwise introduction of additional elements of the physical environment. The next step will be enabling the dycore to run using realistic Martian topography.
In parallel with the effort to make the SE dycore more Mars friendly we have also begun adding hooks into our framework to allow a user to easily configure and run Mars specific configurations. For the HS configuration we've added the proper defaults for the dycore configuration, new boundary data, and Mars use cases.
In order to move forward from the simple model Mars configurations we will need to develop new and modify existing CAM physics parameterizations. Here too, a baby steps approach will be used by beginning with a very simple suite of physics parameterizations. As CAM-Mars only has radiative transfer (RT) cores specifically tuned for planet Earth, it was a priority to incorporate a new RT core that has been used with planetary environments. To that end, the SOCRATES radiative transfer library has been added to CAM-Mars. SOCRATES is referenced as an external library and a framework interface has been added so that SOCRATES is automatically retrieved, configured and built for use when a Mars run is created. A template radiation interface routine has been provided which will serve as the CAM-Mars interface for SOCRATES. Similar interfaces exist for other planetary models as well as the runes driver of SOCRATES itself which can serve as a template for creating the CAM-Mars Socrates interface.
- Quick Start Guide to running a Mars simulation
- CESM-planets/CAM-Mars Developer Notes
- CAM Documentation
- Link SOCRATES library to CAM executable
- Flesh out CAM-SOCRATES interface
- Add constituents (95% CO2, 5% N2) to the model
- enable advected and non-advected designation and framework to add chemistry
- Define a radiative transfer interface
- Calls necessary init functions (loads correlated-k tables)
- Passes in radiatively active gases
- Accesses necessary calendar functions (e.g., solar zenith angle)
- Returns SW and LW heating/cooling rates and tendency on state variables
- Adds diagnostic variables to history output
- Applies net state tendency
- Docker updates to include latest additions
- Create and debug Mars Topography in HS test setup
- Modify SOCRATES library interface files to allow use of CESM/CAM constants, type definitions, etc.