Modify a nest definition (advanced)

The terminology use below is described in the table below:

term	description
nest	a collection of resolutions
resolution	a rectangular region covered by a specific number of grid points (a.k.a. resolution)

Please note that a single nest, can have multiple resolutions. While a given resolution can provide initial conditions and lateral boundary conditions for the next resolution this is not always the case. Pay attention to the details.

Warning

The numbering of the resolutions can differ between the RAS and RNS (particularly if using EC as a driving model).

Tip

Both the RAS and RNS can create multiple nests at the same time. This capability should only be used by advanced users. Hence, we typically talk about nest 1.

To modify the location and/or the size of the target grids you need to modify both the (RAS and RNS). This is because name changes in the RAS will affect the names and paths required in the RNS.

Modifications to the nest are done in the two (ordered) steps:

1) modify the RAS and run the RAS.

2) modify the RNS and run the RNS.

For further information, see below.

Modify the RAS

To open the rose GUI, run the following command from within the RAS suite directory:

rose edit &

Change the name of the entire nest

To change a nested region name within the rose GUI, navigate to

suite conf → Regional Ancillary Suite → Nested region 1 setup.

Edit the rg01_name field and click the Save button .

For example, to change the the name of the nested region from Lismore to Darwin, set the rg01_name field to Darwin.

Change the central position of the entire nest

The nested region position is usually defined by the latitude and longitude coordinates of the nested region centre.

To change the nested region centre within the rose GUI, navigate to suite conf → Regional Ancillary Suite → Nested region 1 setup. Edit the rg01_centre field and click the Save button .

For example, to set the centre of the nested region to -12.4 / 130.8, set the rg01_centre field to -12.4 / 130.8.

Warning

When changing the land-surface initial conditions source, if using a higher-quality land/surface initial condition it is important to ensure that the centre of the nested region coincides with a pixel from that dataset.

Change the number of resolution definitions contained within the entire nest

To change the number of resolution definitions for the nest within the rose GUI, navigate to suite conf → Regional Ancillary Suite → Nested region 1 setup. Edit the rg01_nreslns field and click the Save button .

Change the name of each individual "resolution" within the over-arching nest

The settings for each resolution nest within a nested region are defined separately.

For nest 1, resolution n, navigate to:

suite conf → Regional Ancillary Suite → Nested region 1 setup → Resolution n setup

Here you can modify the "resolution" name, horizontal grid-length, number of points, offset and other settings.

For example, to set nest 1, resolution 2 name from d1100 to d1000, set the rg01_rs02_name field to d1000.

Modify the RNS

Warning

Domain-specific changes need to be consistent between RAS and RNS. For each of the configuration parameters listed above, consistently change the RNS to match the RAS

Change the nested region name

To change the nested region name within the Rose GUI, navigate to

suite conf → Nesting Suite → Nested region 1 setup.

Edit the rg01_name field and click the Save button .

For example, to set the name of the nested region to Darwin, set the rg01_name field to Darwin.

Change the name of each individual "resolution" within the over-arching nest 1

To change the nest 1, resolution 1 name within the Rose GUI, navigate to

suite conf → Nesting Suite → Nested region 1 setup → Resolution 2 setup .

Edit the rg01_rs01_name field and click the Save button .

For example, to set the resolution name from d1100 to d1000, set the rg01_rs01_name field to d1000.

Lastly, update the following ancillary directories

If you have changed the nested region name or the nested resolution names in the RAS, you need to update the ancillary directory names in each of the nest regions and the driving model if using ERA5 as a driving model. For example, if the RAS nested region name was set to Darwin, replace Lismore and/or the RAS nest 1, resolution 1 name was set to d1000, then update the following paths to where the data now sits in the RAS.

• suite conf → Nesting Suite → Nested region 1 setup → Resolution 1 setup rg01_rs01_ancil_dir field
• suite conf → Nesting Suite → Nested region 1 setup → Resolution 2 setup rg01_rs02_ancil_dir field
• suite conf → Nesting Suite → Driving model setup dm_ec_lam_ancil_dir field (if using ERA5 as a driving model)

Remember to click the Save button .

Tip

Changing the RNS nested region name is not strictly necessary, but it affects the naming of the RNS output directories. Therefore, for consistency, it is strongly recommended for RAS and RNS to have the same nested region names. However, the ancil directory paths must be correct.