ACCESS-OM2: ACCESS Ocean-Sea Ice Model with WOMBAT Biogeochemistry

About the model

ACCESS-OM2-BGC is a global coupled ocean - sea ice model with WOMBAT biogeochemistrydeveloped by COSIMA.

ACCESS-OM2-BGC consists of the MOM 5 ocean model with WOMBAT Biogeochemistry, CICE 5 sea ice model, and a file-based atmosphere called YATM coupled together using OASIS3-MCT v2.0. ACCESS-OM2-BGC builds on the ACCESS-OM (Bi et al., 2013) and AusCOM (Roberts et al., 2007; Bi and Marsland, 2010) models originally developed at CSIRO.

The model code, configurations and performance were described in Kiss et al. (2020), with further details in the draft ACCESS-OM2 technical report. The current code and configurations differ from this version in a number of ways (biogeochemistry, updated forcing, improvements and bug fixes), as described by Solodoch et al. (2022), Hayashida et al. (2023), Menviel et al. (2023) and Wang et al. (2023).

Support

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

Any questions about ACCESS-NRI releases of ACCESS-OM2-BGC should be done through the ACCESS-Hive Forum. See the ACCESS Help and Support topic for details on how to do this.

Build

ACCESS-NRI is using spack, a build from source package manager designed for use with high performance computing. This repository contains a spack environment definition file (spack.yaml) that defines all the essential components of the ACCESS-OM2-BGC model, including exact versions.

Spack automatically builds all the components and their dependencies, producing model component executables. Spack already contains support for compiling thousands of common software packages. Spack packages for the components in ACCESS-OM2-BGC are defined in the spack packages repository.

ACCESS-OM2-BGC is built and deployed automatically to gadi on NCI (see below). However it is possible to use spack to compile the model using the spack.yaml environment file in this repository. To do so follow the instructions on the ACCESS Forum for configuring spack on gadi.

Then clone this repository and run the following commands on gadi: spack env create access-om2-bgc spack.yaml spack env activate access-om2-bgc spack install to create a spack environment called access-om2-bgc and build all the ACCESS-OM2-BGC components, the locations of which can be found using spack find --paths.

In contrast, the COSIMA ACCESS-OM2 repository uses submodules to bring all the code dependencies into a single repository and build all the models together.

Deployment

ACCESS-OM2-BGC is deployed automatically when a new version of the spack.yaml file is committed to this repository and tagged with a new version. All the ACCESS-OM2-BGC components are built using spack on gadi and installed under the vk83 project in /g/data/vk83. It is necessary to be a member of vk83 project to use ACCESS-NRI deployments of ACCESS-OM2-BGC.

The deployment process also creates a GitHub release with the same tag. All releases are available under the Releases page. Each release has a changelog and meta-data with detailed information about the build and deployment, including: - paths on gadi to all executables built in the deployment process (spack.location) - a spack.lock file, which is a complete build provenance document, listing all the components that were built and their dependencies, versions, compiler version, build flags and build architecture - the environment spack.yaml file used for deployment

Additionally the deployment creates environment modulefiles, the standard method for deploying software on gadi. To view available ACCESS-OM2-BGC versions: module use /g/data/vk83/apps/spack/0.20/release/modules/linux-rocky8-x86_64 module avail access-om2-bgc

For users of ACCESS-OM2-BGC model configurations released by ACCESS-NRI the exact location of the ACCESS-OM2-BGC model executables is not required. Model configurations will be updated with new model components when necessary.