ACCESS-OM2: Release Information

ACCESS-OM2

ACCESS-OM2 is a global coupled Ocean-Sea Ice Model developed by COSIMA.

ACCESS-NRI Support

ACCESS-NRI has assumed responsibility for supporting ACCESS-OM2 for the Australian Research Community. As part of this support ACCESS-NRI has developed a new build and deployment system for ACCESS-OM2 to align with plans for supporting a range of Earth System Models.

Release

ACCESS-NRI is releasing its first supported version of the ACCESS-OM2 model.

This version uses the spack package management system to build and deploy the model. This is a very different system from that used by COSIMA, however it is bit-reproducible with the equivalent COSIMA ACCESS-OM2 build.

This release is enabled by a modern DevOps build, test and deployment pipeline developed at ACCESS-NRI. This core software infrastructure will be used to build, test and deploy all ACCESS-NRI models in future, improving efficiency, reliability and reproducibility. All DevOps pipelines are configured and run from GitHub, so they are open and discoverable, including software deployments at NCI.

The key components of the DevOps pipeline:

  1. Continuous Integration (CI) testing
    Modular, centrally maintained and makes it trivial to add to any model code repository, allowing ACCESS-NRI to scale to support many models simultaneously.

  2. Continuous Deployment (CD) of software
    Modular automated continuous deployment pipeline on NCI. Efficiency makes supporting many models possible. Provides reliable and timely model releases to the community.

  3. Spack, a build-from-source package manager for software building and deployment
    All ACCESS-OM2 components now support being built and managed by the spack package manager. Spack is an essential element in the CI build and deployment pipeline: it facilitates building the complex software ecosystem necessary to build modern climate models reproducibly, reliably and across many platforms.

Who is this for?

This initial release can be used by anyone, though only a subset of model configurations are currently supported (see below). This initial release is a proof of concept of our automated deployment pipeline. We welcome any feedback.

There are plans for more extensive support, including upgrades to tools and easy access to model metadata and provenance information. Using the ACCESS-NRI released model now provides improved provenance immediately and more comprehensive testing and quality assurance in the future.

How to use the model

It is necessary to be a member of vk83 project to use ACCESS-NRI deployments of ACCESS-OM2. See NCI Documentation for more information about how to join a project.

Model Configurations

The supported method to use ACCESS-NRI released ACCESS-OM2 model versions is via supported model configurations, which utilise them.

ACCESS-NRI supported configurations are available in this repository:

ACCESS-NRI will be supporting the standard ACCESS-OM2 model configurations, namely 1°, 0.25° and 0.1° global simulations with Interannual (IAF) and Repeat Year Forcing (RYF) based on JRA55-do reanalysis.

The 1° global configrations are the first to be supported with this first release of the ACCESS-NRI supported versions of the models. More supported model configurations will be added as time and resources permit, and will be announced using this topic.

Environment modules

ACCESS-OM2 is also available through the NCI environment module system. The model is deployed using spack, so models are released within a specific spack version.

To access these modules:

module use /g/data/vk83/apps/spack/0.20/release/modules/linux-rocky8-x86_64

To see available access-om2 modules:

module avail access-om2

which produces

----- /g/data/vk83/apps/spack/0.20/release/modules/linux-rocky8-x86_64 -----
access-om2/2023.11.23  

and to load a particular version

module load access-om2/2023.11.22

which produces

Loading access-om2/2023.11.23
  Loading requirement: oasis3-mct/2023.11.09 libaccessom2/2023.10.26 cice5/2023.10.19 mom5/2023.11.09

The access-om2 module loads modules for specific model component versions.

Using module load will add the locations of the model component executables to your $PATH environment variable, as well as set other variables.

You can get some more information from a module with module show, e.g.

$ module show mom5/2023.11.09
-------------------------------------------------------------------
/g/data/vk83/apps/spack/0.20/release/modules/linux-rocky8-x86_64/mom5/2023.11.09:

module-whatis   {MOM is a numerical ocean model based on the hydrostatic primitive equations.}
module          load libaccessom2/2023.10.26
module          load oasis3-mct/2023.11.09
conflict        mom5
prepend-path    --delim : PATH /g/data/vk83/apps/spack/0.20/release/linux-rocky8-x86_64/intel-19.0.5.281/mom5-git.2023.11.09=2023.11.09-ewcdbrfukblyjxpkhd3mfkj4yxfolal4/bin
prepend-path    --delim : CMAKE_PREFIX_PATH /g/data/vk83/apps/spack/0.20/release/linux-rocky8-x86_64/intel-19.0.5.281/mom5-git.2023.11.09=2023.11.09-ewcdbrfukblyjxpkhd3mfkj4yxfolal4/.
setenv          SPACK_MOM5_ROOT /g/data/vk83/apps/spack/0.20/release/linux-rocky8-x86_64/intel-19.0.5.281/mom5-git.2023.11.09=2023.11.09-ewcdbrfukblyjxpkhd3mfkj4yxfolal4
-------------------------------------------------------------------

Currently modules are provided as an information source to help expose what models are deployed and supported at NCI. Using the models via modules will be supported in the future, but this is not a currently supported mode of use.

What should I do to be notified of any updates?

You can watch this topic, and be notified by email of every update to released versions.

All released ACCESS-OM2 models are deployed directly from the GitHub repository and the releases page contains information of all releases, including detailed information of the build provenance and deployment location:

Where do I ask questions?

Replies to this topic are disabled.

If you have specific questions about this release follow the guidelines for requesting help from ACCESS-NRI.

If you have questions about access-om2 create a topic in COSIMA and tag it with access-om2. If you require assistance follow the guidelines for requesting help from ACCESS-NRI.

12/04/2024

ACCESS-OM2 Release Update

New configurations

ACCESS-NRI has released global 1°, 0.25° and 0.1° physics only and biogeochemical (ocean-bgc) configurations of ACCESS-OM2 with both repeat-year and interannual JRA55-do forcing.

There are twelve configurations in total. Experiments configurations are stored as separate specially named branches beginning with release- in the access-om2-configs repository. where you can also find instructions on how to access the configurations.

The ACCESS-Hive instructions for using the ACCESS-OM2 model have also been updated to use ACCESS-NRI infrastructure.

Details of the releases are here:

All the configurations that are being released today use the ACCESS-OM2 model version 2024.03.0 that has restart reproducibility enabled and so are not bitwise reproducible with the equivalent COSIMA configurations on which they are based.

For more information on restart reproducibility and ACCESS-OM2:

Configuration versioning

Model configurations use a MAJOR.MINOR versioning scheme (a modified semantic versioning (semver) scheme).

In this scheme the two components of the version have the following semantic meaning:

  • MAJOR : indicates changes in bitwise reproducibility
  • MINOR : any other change that does not change bitwise reproducibility

What does this mean?

Any configuration that has the same MAJOR version as another version of the same configuration is bitwise comparable, i.e. those experiments are directly comparable within scientific limitations.

Configurations are bitwise reproducible within MAJOR versions. For example, if a configuration is versioned as 2.3, it is bitwise reproducible with any other 2.X configuration.

What version are these released configurations?

All the configurations that are part of this release are versioned as 2.0 as they are not bitwise reproducible with the equivalent COSIMA configurations on which they are based.

Automated Testing

Automated continuous integration (CI) testing has been added to the access-om2-configs repository.

What does this mean?

Every time there is an update to a release-* configuration branch Quality Assurance (QA) checks ensure the model configuration doesn’t have any easily detectable errors. This helps ensure released configurations are of high quality and helps configuration developers avoid common errors.

If QA checks pass then reproducibility checks are done: the configuration is run on gadi for a very short time (typically a day) and a comparison made between the model state and the same model state from the previous version of the configuration. Short runs are also done to test for restart reproducibility.

What if it is bitwise reproducible?

If the model reproduces previous results it is bitwise reproducible. If the proposed changes are merged into the release- configuration the configuration MINOR version is incremented, e.g. if the current version is 2.5 the new version would be 2.6.

What if it isn’t bitwise reproducible?

If the model doesn’t reproduce previous results it is not bitwise reproducible. If the proposed changes are merged into the release- configuration the configuration MAJOR version is incremented and the MINOR version set to zero, e.g. if the current version is 2.5 the new version would be 3.0. In this case the reproducibility checksums that represent the model state would also be updated to the values for the new MAJOR version.

Release

When a change to release- branch is merged the version is always updated. This also triggers the merge commit to be automatically tagged. The tag contains the branch name with the version appended, and this also automatically creates a release that is visible in the release page

The releases page contains details of the changes for each release, and is a useful source of information about configurations.

Why is this testing important?

Automatic reproducibility testing means configurations will not be altered and change bitwise reproducibility without that being obvious (change in MAJOR version). It makes it clear what experiments are comparable and provides certainty.

The testing is also part of the automated release process, so you can be certain that the configuration used for your experiments has been tested and tagged appropriately.

Where do I ask questions?

Replies to this topic are disabled.

If you have specific questions about this release follow the guidelines for requesting help from ACCESS-NRI .

If you have questions about access-om2 create a topic in COSIMA and tag it with access-om2. If you require assistance follow the guidelines for requesting help from ACCESS-NRI .

19/04/2024

Updated to include released 0.25° configurations

22/04/2024

Updated to include link to ACCESS-OM2 model version release.

11/07/2024

ACCESS-OM2 Release Update

New configurations

ACCESS-NRI has released new versions of the global 1°, 0.25° and 0.1° biogeochemical configurations. The physics-only configurations have not been updated. The new releases include a bug-fix to the ice-to-ocean BGC tracer fluxes in WOMBAT.

Details of the releases are here:

What version are these released configurations?

The released configurations are version 3.0 indicating that they are not bitwise reproducible with their previous versions (version 2.0).

How do I use these releases

See the ACCESS-Hive instructions for using the ACCESS-OM2 model. All release-*_bgc branches in the access-om2-configs repository include this update.

Where do I ask questions?

Replies to this topic are disabled.

If you have specific questions about this release please follow the guidelines for requesting help from ACCESS-NRI.

22/12/2025

ACCESS-OM2 Release Update

New configurations

ACCESS-NRI has released new versions of the global 1°, 0.25° and 0.1° physics-only configurations. The biogeochemical configurations have not been updated. Key changes in the new releases are:

All configurations

  • Update to a new version of MOM5 that allows using ACCESS-OM2 with coupled generic-tracers, including WOMBATlite/mid.
  • Update from Intel Classic to oneAPI compilers.

1° and 0.1° configurations only

  • Fixes to the CICE grid. These fixes were already included in version 2.0 of the 0.25° configurations.

Details of the releases, including a full list of changes, are here:

What version are these released configurations?

The released configurations are version 3.0 indicating that they are not bitwise reproducible with their previous versions (version 2.0). Specifically, the changes to the CICE grid and compiler updates do not preserve answers.

How do I use these releases

See the ACCESS-Hive instructions for using the ACCESS-OM2 model. All non-BGC release-* branches in the access-om2-configs repository have been updated.

Credits

These releases build on the collective efforts of many people over many years. Contributors to the version 3.0 configurations include:

Where do I ask questions?

Replies to this topic are disabled.

If you have specific questions about the releases in this topic please follow the guidelines for requesting help from ACCESS-NRI.

ACCESS-OM2 release update, 24/06/2026

ACCESS-NRI has released 12 ACCESS-OM2 global configurations. Of these 12 releases, 6 are updates to the existing physics-only configurations and 6 are new configurations that use the new WOMBATlite ocean BGC model.

Updated physics-only configurations

All previously-released physics-only configurations have been updated (global 1°, 0.25° and 0.1°, with both repeat-year (RYF) and interannual (IAF) JRA55-do forcing).

Key updates

  • Consistent latent heat of vaporisation used in MOM and CICE.
  • Multiple time steps per history file in CICE native output.
  • Updated ocean diagnostic filename convention for consistency with other ACCESS models.
  • Configuration performance info now available in README.
  • Moved make_diag_table.py to a shared location in /g/data/vk83/apps.
  • IAF only: Updated forcing from JRA55-do 1.4.0 to 1.6.0 and extend cycle end from 2019 to 2024.
  • 0.25° only: Fixed issue with configurations not being restart reproducible (meaning two short consecutive runs, separated by a restart, gave different results than a single long run).

What version are these released configurations?

The released configurations are version 4.0 indicating that they are not bitwise reproducible with their previous versions (version 3.0). Specifically, the changes to the latent heat of vaporisation do not preserve answers.

New WOMBATlite configurations

There is a new WOMBATlite-enabled configuration for each of the physics-only configurations described above (i.e. global 1°, 0.25° and 0.1°, with both repeat-year and interannual JRA55-do forcing). These configurations follow the same naming scheme as the physics-only configurations, but with +wombatlite appended. E.g. the 1° RYF configuration release branch is called release-1deg_jra55_ryf+wombatlite.

These configurations replace the ACCESS-OM2 release-*_bgc configurations which use a legacy version of WOMBAT and will no longer be maintained.

Key features

  • New WOMBATlite model, version 2026.05.000. Key improvements over the legacy version of WOMBAT are:
    • More realistic phytoplankton physiology: phytoplankton photo-acclimate (vary Chl), perform luxury uptake of Fe, have size-dependent nutrient affinities, and respond mechanistically to Fe, light and nutrient limitation.
    • Improved iron cycle: Fe includes ligand binding, scavenging, colloidal coagulation, and zooplankton-driven Fe-rich egestion into particles.
    • Expanded carbon, nitrogen and particle cycles: WOMBATlite includes dynamic CaCO₃ production and dissolution, optional N-fixation and denitrification, variable particle sinking velocities, river inputs, updated atmospheric Fe sources and sediment burial.
    • Model calibration: WOMBATlite has been constrained/optimized against eight global observational datasets.
    • Overall, WOMBATlite is a more complete, yet still computationally efficient, ocean biogeochemical model. See the WOMBATlite 2026.05.000 documentation for more details.
  • Unlike the configurations that use the legacy version of WOMBAT, the new configurations:
    • are restart reproducible;
    • do not include the CICE5 skeletal layer BGC scheme.
  • Based on the latest (version 4.0) physics-only configurations.

What version are these released configurations?

The released configurations are the first set of released configurations that use WOMBATlite. They are version 1.0.

Control experiments

ACCESS-NRI plan to generate and share control experiments for at least a subset of these new configurations. We will reach out soon to gather input from the community, particularly on what diagnostics may be of interest.

How do I use these releases?

See the ACCESS-Hive instructions for using the ACCESS-OM2 model.

Details of the releases, including a full list of changes, are here:

Credits

These releases build on the collective efforts of many people over many years. Contributors to the configuration versions in this release announcement include:

Where do I ask questions?

Replies to this topic are disabled.

If you have specific questions about the releases in this topic please follow the guidelines for requesting help from ACCESS-NRI.