Setting up a new domain

The following files are domain specific and have to be created for a new domain:

Environment name in job_settings	Description	Can be created with	Example from the SPICE distribution

Environment name in job_settings	Description	Can be created with	Example from the SPICE distribution
LAM_GRID	Grid description of the limited area dynamic grid	ICON Webservice	europe044_DOM01.nc
PARENT_GRID	Grid description of the parent grid	ICON Webservice	europe044_DOM01.parent.nc
EXTPAR	External parameters on ICON grid	ICON Webservice	external_parameter_icon_europe044_DOM01_tiles.nc
TARGET_GRID	External data file holding grid information of the domain in rotated coordinates. This information is needed in the post-processing for interpolation from ICON grid to the rotated lat/lon grid	WebPEP@DKRZ	europe044_rotated_grid.nc

As an example the CORDEX South-East Asia domain is taken. You can see this example at the end of each step.

Step 1
If you already have a netCDF file that holds the rotated coordinate information for your desired domain you can use this for your TARGET_GRID and proceed to step 2.
Choose the region with the WebPEP-go interface (WebPEP-go) (do not use the normal WebPEP interface, this would create too much overhead). There is no need to take account of extra grid boxes at the boundaries (e.g. for a sponge layer). Then click the "create grid" button. In a new window you will get the cfu command you can use to create your grid file. The cfu command is the one that is distributed with the SPICE scripts.
The grid file is your TARGET_GRID file.

CORDEX South-East Asia domain SEA-44

Select the domain in WebPEP-go
Shown after you click the "create grid" button
Create the rotated grid file `SEA-44_rotated.nc` on your system	`cfu create_rotgrid 89.15 -15.07 0.44 0.44 132 97 0 90 180 SEA-44_rotated.nc`

You have now created your target grid file:

TARGET_GRID=SEA-44_rotated.nc

Step 2
If you already have the appropriate RxxByy values for your ICON simulation you can skip to step 3.
You can use the R and B finder tool to find the R and B values nearest to the grid mesh width you choose in step 1.

CORDEX South-East Asia domain SEA-44

A grid width of 0.44 degrees gives 48.88884 km (=0.44*111.111)

Step 3

In order to make it easier for you to create the ICON grid that covers your desired domain with the ICON Webservice interface, you may use the cfu command

cfu icon_domain <netcdf file> [<nbound> [<nudge_zone_width> <Rn> <Bk>] ]

see SPICE documentation for explanation of this command.
The input file is the grid file you created in step 1.

CORDEX South-East Asia domain SEA-44

Create grid description input for

nudge_zone_width = 10

R13B03

and 2 safety grid boxes

cfu icon_domain SEA-44_rotated.nc 2 10 13 3

This gives the output shown at the right.

You can use these values in the ICON Webservice in step 4

Step 4
The files for LAM_GRID, PARENT_GRID, EXTPAR will now be created by the ICON Webservice. You can use the information you have got in steps 3 and 4 for this.

CORDEX South-East Asia domain SEA-44

Visit the ICON Webservice and put in the numbers you got from the previous steps. For the parent grid you set R13B02 in our case, i.e. one number less in B.

Put in your address and the the R and B values for the parent grid
"untick" the spring dynamics optimization
Use the output of the `cfu icon_domain` command to fill out the domain values

When you are ready push the Proceed button. You will receive an email when the data are ready including a description how to download them. In this example case you will receive the following data files:

Step 5

In case the external data file is in netCDF4 format the data file may have to be transformed into netCDF3. This depends on the CDO version you use. CDO versions from 2.x onwards can read netCDF4. Check with

and transform with

Step 6

Copy the mandatory files into your grid description directory.

CORDEX South-East Asia domain SEA-44

Put the following into job_settings, and replace PATHtoDATA with the path where you copied the data to.

Step 7

Adjust the valid range of output variables to your domain and/or resolution for samovar checks. For certain regions adapted lists are already given, e.g. samovar_EUR-11.csv and samovar_ts_EUR-11.csv