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General prerequisites

Before running ACCESS-ESM, you need to fulfil general prerequisites outlined in the First Steps section.

If you are unsure whether ACCESS-ESM is the right choice for your experiment, take a look at the overview of ACCESS Models.

Model-specific prerequisites

ACCESS-ESM is installed on NCI's supercomputer Gadi and uses payu, a tool for running and managing model experiments. Following these prerequisites ensures you have access to this infrastructure.

  • Join the access and hh5 projects at NCI
    To join these projects, request membership on the respective access and hh5 NCI project pages.
    For more information on joining specific NCI projects, refer to How to connect to a project.
  • Payu
    Payu on Gadi is available through the conda/analysis3 environment in the hh5 project.
    After obtaining hh5 project membership, load the conda/analysis3 environment to automatically retrieve payu as follows:
    module use /g/data/hh5/public/modules
    module load conda/analysis3
    To check that payu is available, run:
    payu --version
    payu --version 1.0.19

Get ACCESS-ESM configuration

ACCESS-ESM configurations are available on the coecms GitHub, collated in a single repository.
To get it on Gadi, clone the ACCESS-ESM GitHub repo by running:

git clone

This will create the access-esm folder. git clone Cloning into 'access-esm'... remote: Enumerating objects: 1625, done. remote: Counting objects: 100% (1625/1625), done. remote: Compressing objects: 100% (575/575), done. remote: Total 1625 (delta 1042), reused 1621 (delta 1040), pack-reused 0 Receiving objects: 100% (1625/1625), 2.79 MiB | 11.24 MiB/s, done. Resolving deltas: 100% (1042/1042), done. ls ~/access-esm atmosphere config.yaml coupler ice manifests ocean

Some modules may interfere with git commands (e.g., matlab/R2018a). If you have trouble cloning the repository, run the following command before trying again:
module purge
After this step, don't forget to reload the conda/analysis3 module to retrieve payu, as specified in the Model-specific prerequisites section.

Different ACCESS-ESM configurations are stored in different branches of the ACCESS-ESM GitHub repo. To check all the available branches on the repo, run the following command inside the newly-created access-esm folder:

git branch -a

cd ~/access-esm git branch -a ٭ main remotes/origin/82ka remotes/origin/HEAD → origin/main remotes/origin/ccarouge-patch-1 remotes/origin/historical remotes/origin/last-interglacial remotes/origin/last-millenium remotes/origin/last-millenium-detailed remotes/origin/main remotes/origin/mid-holocene remotes/origin/pre-industrial remotes/origin/ssp585 The green-coloured branch (preceded by a star sign *) indicates the local branch you are currently in.
The red-coloured branches are the available remote branches, formatted as remotes/origin/<branch-name>. To switch to a specific branch you can run the following command:

git checkout <branch-name>

For example, the pre-industrial configuration of ACCESS-ESM is available in the pre-industrial branch. To use the pre-industrial configuration, run:

git checkout pre-industrial

git checkout pre-industrial branch 'pre-industrial' set up to track 'origin/pre-industrial'. Switched to a new branch 'pre-industrial' git branch   main ٭ pre-industrial

Edit ACCESS-ESM configuration

It is good practice to create a new git branch to store all your modifications for a particular run, so as not to modify the reference configuration.

To create a new branch called "example_run", as a copy of the pre-industrial branch, from within the access-esm directory execute:

git checkout -b example_run --no-track origin/pre-industrial

This command will also switch to the new example_run branch. git branch   main ٭ pre-industrial git checkout -b example_run --no-track origin/pre-industrial Switched to a new branch 'example_run' git branch ٭ example_run   main   pre-industrial


Payu is a workflow management tool for running numerical models in supercomputing environments.
The general layout of a payu-supported model run consists of two main directories:

  • The laboratory directory, where all the model components reside. For ACCESS-ESM, it is typically /scratch/$PROJECT/$USER/access-esm.
  • The control directory, where the model configuration resides and from where the model is run (in this example, the cloned directory ~/access-esm).

This distinction of directories separates the small-size configuration files from the larger binary outputs and inputs. In this way, the configuration files can be placed in the $HOME directory (as it is the only filesystem actively backed-up on Gadi), without overloading it with too much data. Furthermore, this separation allows multiple self-resubmitting experiments that share common executables and input data to be run simultaneously.

To setup the laboratory directory, run the following command from the control directory:

payu init

This creates the laboratory directory, together with relevant subdirectories, depending on the configuration. The main subdirectories of interest are:

  • work → a temporary directory where the model is run. It gets cleaned after each run.
  • archive → the directory where output is stored after each run.
  • cd ~/access-esm/esm-pre-industrial payu init laboratory path: /scratch/$PROJECT/$USER/access-esm binary path: /scratch/$PROJECT/$USER/access-esm/bin input path: /scratch/$PROJECT/$USER/access-esm/input work path: /scratch/$PROJECT/$USER/access-esm/work archive path: /scratch/$PROJECT/$USER/access-esm/archive

Edit the Master Configuration file

The config.yaml file located in the control directory, is the Master Configuration file.
This file, which controls the general model configuration, contains several parts:

  • PBS resources
    jobname: pre-industrial
    queue: normal
    walltime: 3:10:00
    These lines can be edited to change the PBS directives for the PBS job.
    For example, to run ACCESS-ESM under the tm70 project (ACCESS-NRI), add the following line:
    project: tm70
    The project entry should always refer to a project with allocated Service Units (SU), that you are a member of. If not set explicitly, ACCESS-ESM will run using your default project (this default project still needs to have allocated SU). For more information, check how to join relevant NCI projects.
  • Link to the laboratory directory
    # note: if laboratory is relative path, it is relative to /scratch/$PROJECT/$USER
    laboratory: access-esm
    These lines set the laboratory directory path, which is relative to /scratch/$PROJECT/$USER. Absolute paths can also be specified.
  • Model
    model: access
    This line tells payu which driver to use for the main model (access refers to ACCESS-ESM).
  • Submodels
        - name: atmosphere
          model: um
          ncpus: 192
          exe: /g/data/access/payu/access-esm/bin/coe/um7.3x
            - /g/data/access/payu/access-esm/input/pre-industrial/atmosphere
            - /g/data/access/payu/access-esm/input/pre-industrial/start_dump
    - name: ocean model: mom ncpus: 180 exe: /g/data/access/payu/access-esm/bin/coe/mom5xx input: - /g/data/access/payu/access-esm/input/pre-industrial/ocean/common - /g/data/access/payu/access-esm/input/pre-industrial/ocean/pre-industrial
    - name: ice model: cice ncpus: 12 exe: /g/data/access/payu/access-esm/bin/coe/cicexx input: - /g/data/access/payu/access-esm/input/pre-industrial/ice
    - name: coupler model: oasis ncpus: 0 input: - /g/data/access/payu/access-esm/input/pre-industrial/coupler
    ACCESS-ESM is a coupled model deploying multiple submodels (i.e. model components). This section specifies the submodels and configuration options required to execute the model correctly.
    Each submodel contains additional configuration options that are read in when the submodel is running. These options are specified in the subfolder of the control directory, whose name matches the submodel's name (e.g., configuration options for the atmosphere submodel are in the ~/access-esm/esm-pre-industrial/atmosphere directory).
  • Collate
        exe: /g/data/access/payu/access-esm/bin/mppnccombine
        restart: true
        mem: 4GB
    The collate process combines a number of smaller files, which contain different parts of the model grid, into target output files. Restart files are typically tiled in the same way and will also be combined together if the restart option is set to true.
  • Restart
    restart: /g/data/access/payu/access-esm/restart/pre-industrial
    This is the location of the files used for a warm restart.
  • Start date and internal run length
            year: 101
            month: 1
            days: 1
    runtime: years: 1 months: 0 days: 0
    This section specifies the start date and internal run length.
    The internal run length (controlled by runtime) can be different from the total run length. Also, while runtime can be reduced, it should not be increased to more than 1 year to avoid errors. For more information about the difference between internal run and total run lengths, or how to run the model for more than 1 year, refer to the section Run configuration for multiple years.
  • Number of runs per PBS submission
    runspersub: 1
    ACCESS-ESM configurations are often run in multiple steps (or cycles), with payu running a maximum of runspersub internal runs for every PBS job submission.
    If you increase runspersub, you may need to increase the walltime in the PBS resources.

To find out more about other configuration settings for the config.yaml file, check out how to configure your experiment with payu.

Edit a single ACCESS-ESM component configuration

Each of ACCESS-ESM components contains additional configuration options that are read in when the model component is running. These options are typically useful to modify the physics used in the model or the input data. They are specified in the subfolder of the control directory, whose name matches the submodel's name as specified in the config.yaml submodel section (e.g., configuration options for the atmosphere submodel are in the ~/access-esm/esm-pre-industrial/atmosphere directory). To modify these options please refer to the User Guide of each individual model component.

Run ACCESS-ESM configuration

After editing the configuration, you are ready to run ACCESS-ESM.
ACCESS-ESM suites run on Gadi through a PBS job submission managed by payu.

Payu setup (optional)

As a first step, from within the control directory, it is good practice to run:

payu setup

This will prepare the model run, based on the experiment configuration. payu setup laboratory path: /scratch/$PROJECT/$USER/access-esm binary path: /scratch/$PROJECT/$USER/access-esm/bin input path: /scratch/$PROJECT/$USER/access-esm/input work path: /scratch/$PROJECT/$USER/access-esm/work archive path: /scratch/$PROJECT/$USER/access-esm/archive Loading input manifest: manifests/input.yaml Loading restart manifest: manifests/restart.yaml Loading exe manifest: manifests/exe.yaml Setting up atmosphere Setting up ocean Setting up ice Setting up coupler Checking exe and input manifests Updating full hashes for 3 files in manifests/exe.yaml Creating restart manifest Updating full hashes for 30 files in manifests/restart.yaml Writing manifests/restart.yaml Writing manifests/exe.yaml

This step can be skipped as it is also included in the run command. However, running it explicitly helps to check for errors and make sure executable and restart directories are accessible.

Run configuration

To run ACCESS-ESM configuration for one internal run length (controlled by runtime in the config.yaml file), execute:

payu run -f

This will submit a single job to the queue with a total run length of runtime. If there is no previous run, it will start from the start date indicated in the config.yaml file. Otherwise, it will perform a warm restart from a previously saved restart file.

The -f option ensures that payu will run even if there is an existing non-empty work directory created from a previous failed run.

payu run -f Loading input manifest: manifests/input.yaml Loading restart manifest: manifests/restart.yaml Loading exe manifest: manifests/exe.yaml payu: Found modules in /opt/Modules/v4.3.0 qsub -q normal -P <project> -l walltime=11400 -l ncpus=384 -l mem=1536GB -N pre-industrial -l wd -j n -v PAYU_PATH=/g/data/hh5/public/apps/miniconda3/envs/analysis3-23.01/bin,MODULESHOME=/opt/Modules/v4.3.0,MODULES_CMD=/opt/Modules/v4.3.0/libexec/modulecmd.tcl,MODULEPATH=/g/data3/hh5/public/modules:/etc/scl/modulefiles:/opt/Modules/modulefiles:/opt/Modules/v4.3.0/modulefiles:/apps/Modules/modulefiles -W umask=027 -l storage=gdata/access+gdata/hh5 -- /g/data/hh5/public/apps/miniconda3/envs/analysis3-23.01/bin/python3.9 /g/data/hh5/public/apps/miniconda3/envs/analysis3-23.01/bin/payu-run <job-ID>.gadi-pbs

Run configuration for multiple years

If you want to run ACCESS-ESM configuration for multiple internal run lengths (controlled by runtime in the config.yaml file), use the option -n:

payu run -f -n <number-of-runs>

This will run the configuration number-of-runs times with a total run length of runtime * number-of-runs. The number of consecutive PBS jobs submitted to the queue depends on the runspersub value specified in the config.yaml file.

Understand runtime, runspersub, and -n parameters

With the correct use of runtime, runspersub and -n parameters, you can have full control of your run.

  • runtime defines the internal run length.
  • runspersub defines the maximum number of internal runs for every PBS job submission.
  • -n sets the number of internal runs to be performed.

Now some practical examples:

  • Run 20 years of simulation with resubmission every 5 years
    To have a total run length of 20 years with a 5-year resubmission cycle, leave runtime as the default value of 1 year and set runspersub to 5. Then, run the configuration with -n set to 20:
    payu run-f -n 20
    This will submit subsequent jobs for the following years: 1 to 5, 6 to 10, 11 to 15, and 16 to 20, which is a total of 4 PBS jobs.
  • Run 7 years of simulation with resubmission every 3 years
    To have a total run length of 7 years with a 3-year resubmission cycle, leave runtime as the default value of 1 year and set runspersub to 3. Then, run the configuration with -n set to 7:
    payu run -f -n 7
    This will submit subsequent jobs for the following years: 1 to 3, 4 to 6, and 7, which is a total of 3 PBS jobs.
  • Run 3 months and 10 days of simulation in a single submission
    To have a total run length of 3 months and 10 days in a single submission, set the runtime as follows:
    years: 0
    months: 3
    days: 10
    Set runspersub to 1 (or any value > 1) and run the configuration without option -n (or with -n set to 1):
    payu run -f
  • Run 1 year and 4 months of simulation with resubmission every 4 months
    To have a total run length of 1 year and 4 months (16 months), you need to split it into multiple internal runs. For example, 4 internal runs of 4 months each. In this case, set the runtime as follows:
    years: 0
    months: 4
    days: 0
    Since the internal run length is set to 4 months, set runspersub to 1 to resubmit your jobs every 4 months (i.e. every internal run). Then, run the configuration with -n set to 4:
    payu run -f -n 4

Monitor ACCESS-ESM runs

Currently, there is no specific tool to monitor ACCESS-ESM runs.
You can execute the following command to show the status of all your submitted PBS jobs:

qstat -u $USER

qstat -u $USER Job id                Name             User             Time Use S Queue --------------------- ---------------- ---------------- -------- - ----- <job-ID>.gadi-pbs     pre-industrial   <$USER>            <time> R normal-exec <job-ID-2>.gadi-pbs   <other-job-name> <$USER>            <time> R normal-exec <job-ID-3>.gadi-pbs   <other-job-name> <$USER>            <time> R normal-exec If you changed the jobname in the PBS resources of the Master Configuration file, that will appear as your job's Name instead of pre-industrial.
S indicates the status of your run, where:

  • Q → Job waiting in the queue to start
  • R → Job running
  • E → Job ending

If there are no jobs listed with your jobname (or if no job is listed), your run either successfully completed or was terminated due to an error.

Stop a run

If you want to manually terminate a run, you can do so by executing:

qdel <job-ID>

Error and output log files

While the model is running, payu saves the standard output and standard error in the respective access.out and access.err files in the control directory. You can examine the contents of these files to check on the status of a run as it progresses.
When the model completes its run, or if it crashes, the output and error log files are by default renamed as jobname.o<job-ID> and jobname.e<job-ID>, respectively.

Model Live Diagnostics

ACCESS-NRI developed the Model Live Diagnostics framework to check, monitor, visualise, and evaluate model behaviour and progress of ACCESS models currently running on Gadi.
For a complete documentation on how to use this framework, check the Model Diagnostics documentation.

ACCESS-ESM outputs

At the end of the model run, output files (and restart files) are moved from the work directory into the archive directory under /scratch/$PROJECT/$USER/access-esm/archive/access-esm, where they are further subdivided for each internal run. They are also symlinked in the control directory to ~/access-esm/archive
The naming format for a typical output folder is outputXXX and for a restart folder restartXXX, where XXX is the internal run number starting from 000.

A run with a different ACCESS-ESM configuration (different git branch) counts as a new internal run.
Thus, if output folders already exist, the internal number of the new output folder will be set to the first available XXX number.

Outputs and restarts are separated in the respective folders for each model component.
For the atmospheric output data, the files are usually UM fieldsfile, formatted as <UM-suite-identifier>a.p<output-stream-identifier><time-identifier>. cd /scratch/$PROJECT/$USER/access-esm/archive/esm-pre-industrial ls output000 pbs_logs restart000 ls output000/atmosphere aiihca.daa1210 aiihca.daa1810 aiihca.paa1apr aiihca.paa1jun aiihca.pea1apr aiihca.pea1jun aiihca.pga1apr aiihca.pga1jun atm.fort6.pe0 exstat ihist prefix.CNTLGEN UAFLDS_A aiihca.daa1310 aiihca.daa1910 aiihca.paa1aug aiihca.paa1mar aiihca.pea1aug aiihca.pea1mar aiihca.pga1aug aiihca.pga1mar cable.nml fort.57 INITHIS prefix.PRESM_A aiihca.daa1410 aiihca.daa1a10 aiihca.paa1dec aiihca.paa1may aiihca.pea1dec aiihca.pea1may aiihca.pga1dec aiihca.pga1may CNTLALL ftxx input_atm.nml SIZES xhist aiihca.daa1510 aiihca.daa1b10 aiihca.paa1feb aiihca.paa1nov aiihca.pea1feb aiihca.pea1nov aiihca.pga1feb aiihca.pga1nov CONTCNTL namelists STASHC aiihca.daa1610 aiihca.daa1c10 aiihca.paa1jan aiihca.paa1oct aiihca.pea1jan aiihca.pea1oct aiihca.pga1jan aiihca.pga1oct debug.root.01 ftxx.vars nout.000000 thist aiihca.daa1710 aiihca.daa2110 aiihca.paa1jul aiihca.paa1sep aiihca.pea1jul aiihca.pea1sep aiihca.pga1jul aiihca.pga1sep errflag hnlist prefix.CNTLATM UAFILES_A


Last update: April 22, 2024