Replace SST/sea-ice

The following replacement higher-quality sea surface temperature and sea ice dataset exist and can be used in place of the driving model values in the RNS:

dataset	resolution
OSTIA	0.05°

The RNS trunk has the ability to use global OSTIA ancillary files to replace SST and sea-ice values in the forecast both at the start of the run daily at 06Z.

There is an archive of global OSTIA ancillary files at the Met Office. Instead of mirroring the Met Office global OSTIA ancillary archive ACCESS-NRI with NCI has made the full native OSTIA archive available to Australian researchers.

A rose/cylc suite has been developed to transform the OSTIA data from its native netCDF format to the required UM ancillary file format for use in the RNS.

To replace SST and sea-ice with OSTIA values there are two steps required:

1) modify the OSTIA ancillary suite (OAS) for the dates required.

2) modify the RNS to use the OSTIA files including providing the path to them.

Get the OAS

To get the suite, rosie checkout u-dk517

Modify the OAS

OSTIA data is required for each day of the run in your experiment (plus sometimes the day prior, depending on start/end times).

Navigate to suite conf → Ostia ancillary Generation Suite → Cycling options

Modify the INITIAL_CYCLE_POINT

Modify the FINAL_CYCLE_POINT

Modify the OSTIA_OUTPUT directory

Then, rose suite-run

Modify the RNS

Update the OSTIA settings

To change the land-surface initial conditions source within the Rose GUI for the RNS, navigate to

suite conf → Nesting Suite → Cycling options.

Set USE_OSTIA to True and update global_ostia_dir to match the OAS OSTIA_OUTPUT directory.

Tip

If OSTIA ancillaries are being kept in a project other than the one used to run the RNS, add the directory to NCI_STORAGE.

i.e. if you are using files kept on vk83, but not running the RNS on project vk83, navigate to:

suite conf → Nesting Suite → General options

then add +gdata/vk83 to NCI_STORAGE.