Running Global Simulations

How to run global simulations (aquaplanets and AMIP-style configurations) on the cubed sphere.

From a script

The default AtmosSimulation is already global: a cubed-sphere grid with a decaying temperature profile (see Your First Simulation). The quickest physically interesting global run is the aquaplanet preset, which pairs a moist model with an aquaplanet surface:

import ClimaAtmos as CA

simulation = CA.Presets.aquaplanet(Float32; t_end = "1days")
CA.solve_atmos!(simulation)

Customize it through the grid (SphereGrid), the setup, and the AtmosModel components. Horizontal resolution is set by h_elem, the number of spectral elements per cube edge: h_elem = 6 corresponds to about 550 km, 16 to about 206 km, and 30 to about 110 km.

From a configuration file

The aquaplanet configurations in config/model_configs/ (e.g., prognostic_edmfx_aquaplanet.yml, aquaplanet_equil_allsky_gw_raw.yml) and the production-oriented configurations in config/longrun_configs/ (e.g., longrun_aquaplanet_allsky_progedmf_1M.yml, amip_target.yml) are the best starting points:

import ClimaAtmos as CA

config = CA.AtmosConfig(
    "config/model_configs/prognostic_edmfx_aquaplanet.yml";
    job_id = "my_aquaplanet",
)
simulation = CA.AtmosSimulation(config)
CA.solve_atmos!(simulation)

Many model configurations already pin their grid and timestep (the file above sets a reduced vertical resolution so it runs quickly). Combining a numerics file from config/common_configs/ with a model configuration, as described in Creating custom configurations, applies only to model configurations that do not fix those keys themselves; later files override earlier ones key by key.

Output lands in output/<job_id> (see Loading and Visualizing Output). The tested global production configurations can be found in config/longrun_configs/. For GPU runs, see Running on GPUs and MPI.