# ACCESS-OM2: Release Information **URL:** \ **Category:** ACCESS-NRI Releases\ **Tags:** release, access-om2, model\ **Created:** [16 November 2023 07:24 UTC](https://forum.access-hive.org.au/t/access-om2-release-information/1602 "2023-11-16T07:24:59Z")\ **Posts on this page:** 1\ **Showing post:** 6
**Author:** ![dougiesquire](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/dougiesquire/32/16_2.png) [@dougiesquire](https://forum.access-hive.org.au/u/dougiesquire)\ **Post date:** [24 June 2026 03:05 UTC](https://forum.access-hive.org.au/t/access-om2-release-information/1602/6 "2026-06-24T03:05:00Z")
# 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](https://zenodo.org/records/20278397). 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](https://wombat-docs.readthedocs.io/2026.05.000/Model_description/WOMBATlite_model_description/) 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](https://docs.access-hive.org.au/models/run_a_model/run_access-om2/). Details of the releases, including a full list of changes, are here: > **[Releases · ACCESS-NRI/access-om2-configs](https://github.com/ACCESS-NRI/access-om2-configs/releases)** > > Standard ACCESS-OM2 configurations released and supported by ACCESS-NRI - ACCESS-NRI/access-om2-configs ## Credits These releases build on the collective efforts of many people over many years. Contributors to the configuration versions in this release announcement include: - Model development: @pearseb, @dougiesquire, @anton, @spencerwong - Build infrastructure: @TommyGatti, @dougiesquire, @anton - Configuration development and testing: @dougiesquire, @pearseb, @anton, @Qianhui_Chen ## 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](https://forum.access-hive.org.au/t/access-help-and-support/908). --- _[View the full topic](https://forum.access-hive.org.au/t/access-om2-release-information/1602)._