Restart files

ACCESS-OM3 uses a directory of restart files to record how to initialise the model when continuing or branching from an existing experiment.

Changing Restart Dates

The current date and time corresponding to the model state is also saved in these restart files. It may make sense to change this date in restart files, so that a new experiment can use model state from one experiment while applying surface forcing conditions from a different time. For example, a repeat cycle of an inter-annual forcing (IAF) experiment reuses the model state from the end of the previous cycle, but restarts the forcing from the beginning of the forcing period.

The modify_restart_date.py script handles this: it renames the restart files, updates the internal date metadata that cpl/cice restarts carry, and points your new experiment's config.yaml at the result. This script is run in the configuration folder for a new experiment. To use this script:

Check out the configuration for the new experiment

Use payu clone and specify the restart as the path to the directory of existing (unmodified) restart files
cd into the new experiment, double check the restart: path in config.yaml and run the script:
```
python3 /g/data/vk83/apps/om3-scripts/restart_modifications/modify_restart_date.py --new_date <YYYY-MM-DD>
```
--new_date defaults to 1958-01-01 if omitted.

The restart: path will now be updated, and the modified restarts are in initial_restart/ inside the configuration directory
Run the experiment
```
payu sweep && payu run
```

Note

The script doesn't currently support WavewatchIII (WW3) restarts.