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ACCESS OM3 Configurations
Release: release-MC_25km_jra_ryf-1.0-beta
This is an initial beta prerelease of a model configuration of ACCESS-OM3. This uses a release of the ACCESS-OM3 software (version 2025.05.001), a global grid with 25km nominal resolution, bathymetry generated from GEBCO 2024 and initial conditions generated from WOA2023. A 1990-91 Repeat Year Forcing (RYF) extracted from the JRA55-do v1.6 reanalysis is used as input data.
ACCESS-OM3 is the third generation of the ACCESS global ocean - sea ice model. It uses up-to-date releases of the MOM6 ocean model and CICE6 sea ice model. It is the first ACCESS model that couples model components using CMEPS (Community Mediator for Earth Prediction Systems), built on top of NUOPC (National Unified Operational Prediction Capability) infrastructure.
This configuration release is for two key purposes:
- to assess scientific validity of the configuration;
- to seek feedback from Australian climate researchers on model suitability, usability and documentation.
Feedback on these two points can be provided in the general feedback thread.
Control Experiment
There is a data from short control experiment using this model configuration at
/g/data/ol01/access-om3-output/access-om3-025/MC_25km_jra_ryf-1.0-beta
and two examples loading data are provided:
For researchers interested in point 1 above, we suggest starting with this dataset.
Model Configurations
This is the first public release for ACCESS-OM3; further coarse and high resolution configurations are planned. More supported model configurations will be added as time and resources permit. Future release of ACCESS-OM3 configurations will be announced using this topic.
How to use the model
The configuration is run using the payu experiment manager. For instructions, see the access-hive Run ACCESS-OM3 documentation.
What we expect you’ll be able to do with this release:
- Clone the config repo;
- Run the 25km global configuration with JRA55-do RYF forcing;
- Look at output from the model;
- Test sensitivity to model parameter choices
- Discover how the model is configured through ACCESS-OM3 configuration documentation
Importantly, whilst this configuration is considered stable in the software sense, the parameter choices, input files and software code will continue to evolve and improve for some time into the future. There will be newer versions of this configuration which change and improve the model’s results. Users should take care to note results and analysis using this configuration relate to the release-MC_25km_jra_ryf-1.0 tag and later releases will produce different results.
Features
25km global configuration with ocean and sea ice models using data atmosphere and runoff forcings;
global tripolar grid with nearly double the ACCESS-OM2-025 meridional resolution around Antarctica (3.6 km vs. 5.9 km)
vertical z* grid with 75 levels of thicknesses 1.1 m (top) - 198 m (bottom, 5808 m), up from 50 levels from 2.3 m (top) - 220 m (bottom, 5363 m) in ACCESS-OM2-025
CICE6 sea-ice model configured with Bitz & Lipscomb (1999) thermodynamics and Elastic-Viscous Plastic dynamics (Hunke and Dukowicz 1997);
MOM6 ocean model configured with:
- TEOS-10 equation of state: more accurate thermodynamics, especially important for energy budgets and density-driven processes.
- Improved vertical mixing using ePBL: handles mixing based on a local TKE budget rather than fixed vertical shapes, e.g. KPP. ePBL also allows more natural inclusion of effects like Langmuir turbulence.
- Interior shear-driven mixing: Jackson et al. (2008) parameterisation activates mixing when stratification is weak and shear is strong. This is usually used along with ePBL vertical mixing.
- Mixed layer restratification: Bodner et al. (2023) sub-mesoscale parameterisation improves on the original Fox-Kemper formulation. This prevents the restratifying overturning streamfunction from growing unphysically large when surface turbulence is weak.
- Interior diapycnal mixing: tidal-driven diapycnal mixing captures the effects of internal tide-driven turbulence, particularly important over rough topography and in the deep ocean. Uses new bottom roughness data calculated from SYNBATH, and tidal speeds from TPXO10.
- Isopycnal mixing: both the Mesoscale Eddy Kinetic Energy (MEKE), and Gent–McWilliams (GM) schemes based on the streamfunction formulation by Ferrari et al. (2010) are applied. With MEKE enabled, the model is resolution-aware, allowing the thickness diffusion coefficient to adapt to the model resolution.
1990-1991 Repeat Year Forcing using JRA55-do v1.6
bathymetry generated from GEBCO 2024
initial conditions and reference salinity for restoring are generated from WOA2023 (see Limitations below)
known provenance and reproducibility of all input data
deterministic and reproducible outputs and software builds
run-time configuration of model outputs/diagnostics and parameterisations
MOM6 diagnostics on density coordinates are included by default. Note however that these add ~30 min per model year to the runtime and can be removed if not needed. (See instructions)
Limitations
As a beta release, there is no guaranteed support and there is no published model validation.
- Not scientifically validated
- Ocean model configuration allows nonphysical extreme values of sea surface temperature and salinity
- CICE6 uses “B-grid” points for vector quantities (see issue 409)
- Unrealistic ocean salinities at runoff locations (see issue 396)
- Cold-start initial conditions and salt restoring are practical salinity but should be absolute salinity (see issue 235)
- When starting from scratch, the first model year runs more slowly, taking about 5 hours of walltime and ~17.5kSU. From the second year onward, performance improves to around 4 hours 30 minutes of walltime and ~15.5kSU per model year.
- UPDATE: MOM6 scalar diagnostics
thetaogaandtosgaare actually conservative temperature, despite their metadata indicating that they are potential temperature. Similarly,sogaandsosgaare absolute salinity, not practical salinity. See this issue for further details.
For a complete list of known issues, see GitHub issues page.
Credits
The ACCESS-OM3 software is built upon shared components of climate models, developed and supported across many organisations globally. This includes but is not limited to contributors and member organisations of the MOM consortium, the CICE consortium and the Earth System Modelling Framework organization. This configuration is developed from international and local expertise.
Based on configuration choices from Geophysical Fluid Dynamics Laboratory (GFDL) OM5, Community Earth System Model (CESM) 3.0-alpha and ACCESS-OM2
Scoping and approach @aekiss @micael @kieranricardo @MartinDix @AndyHoggANU
Model build infrastructure @harshula @micael @anton @dougiesquire @minghangli
Deployment infrastructure @TommyGatti
Documentation: @atteggiani @aekiss @cbull @ezhilsabareesh8 @anton @dougiesquire @minghangli
Graphics: @OwKal
Grids, initial conditions and bathymetry: @ezhilsabareesh8 @aekiss @dougiesquire @anton @kial
Configuration advice @AndyHoggANU @sofarrell @adele-morrison @MartinDix @aekiss @Luwei @angus-g
Payu development @dougiesquire @jo-basevi @Aidan @anton @minghangli
Test infrastructure & tests @jo-basevi @TommyGatti @dougiesquire @anton @minghangli @Aidan
Model validation and parameter choices: @minghangli @cbull @aekiss @dougiesquire @AndyHoggANU
Performance and software optimisation: @minghangli @micael @manodeep
Support
Replies to this topic are disabled. For feedback, use the General Feedback Thread
For bugs/support requests, Create a topic on the ACCESS-Hive Forum in COSIMA and tag it with help. Support is provided by ACCESS-NRI for products it releases.
Resources
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