4.2. FAQ

4.2.1. How do I define an experiment name?

The name of the experiment is set in the workflow: section of the config.yaml file using the variable EXPT_SUBDIR. See Section and/or Section for more details.

4.2.2. How do I change the Physics Suite Definition File (SDF)?

The SDF is set in the workflow: section of the config.yaml file using the variable CCPP_PHYS_SUITE. The five supported physics suites for the SRW Application are:


When users run the generate_FV3LAM_wflow.py script, the SDF file is copied from its location in the forecast model directory to the experiment directory $EXPTDIR. For more information on the CCPP physics suite parameters, see Section

4.2.3. How do I change the grid?

To change the predefined grid, modify the PREDEF_GRID_NAME variable in the task_run_fcst: section of the config.yaml script (see Section for details on creating and modifying the config.yaml file). The four supported predefined grids as of the SRW Application v2.1.0 release are:


However, users can choose from a variety of predefined grids listed in Section An option also exists to create a user-defined grid, with information available in Section 3.3.2. However, the user-defined grid option is not fully supported as of the v2.1.0 release and is provided for informational purposes only.

4.2.4. How can I select which workflow tasks to run?

The /parm/wflow directory contains several YAML files that configure different workflow task groups. Each task group file contains a number of tasks that are typically run together. Table 4.1 describes each of the task groups.

Table 4.1 Task group files




SRW-AQM post-processing tasks


SRW-AQM pre-processing tasks


Tasks required to run a cold-start forecast


Preprocessing tasks for RRFS DA <data assimilation>.


Plotting tasks


Post-processing tasks


Horizontal map projection processor that creates smaller domain products from the larger domain created by the UPP.


Pre-processing tasks


Deterministic verification tasks


Ensemble verification tasks


Verification pre-processing tasks

The default workflow task groups are set in parm/wflow/default_workflow.yaml and include prep.yaml, coldstart.yaml, and post.yaml. Changing this list of task groups in the user configuration file (config.yaml) will override the default and run only the task groups listed. For example, to omit cycle-independent tasks and run plotting tasks, users would delete prep.yaml from the list of tasks and add plot.yaml:

    taskgroups: '{{ ["parm/wflow/coldstart.yaml", "parm/wflow/post.yaml", "parm/wflow/plot.yaml"]|include }}'

Users may need to make additional adjustments to config.yaml depending on which task groups they add or remove. For example, when plotting, the user should add the plotting increment (PLOT_FCST_INC) for the plotting tasks in task_plot_allvars.

Users can omit specific tasks from a task group by including them under the list of tasks as an empty entry. For example, if a user wanted to run only task_pre_post_stat from aqm_post.yaml, the taskgroups list would include aqm_post.yaml, and the tasks that the user wanted to omit would be listed with no value:

    taskgroups: '{{ ["parm/wflow/prep.yaml", "parm/wflow/coldstart.yaml", "parm/wflow/post.yaml", "parm/wflow/aqm_post.yaml"]|include }}'

4.2.5. How do I turn on/off the cycle-independent workflow tasks?

The first three pre-processing tasks make_grid, make_orog, and make_sfc_climo are cycle-independent, meaning that they only need to be run once per experiment. By default, the the workflow will run these tasks. However, if the grid, orography, and surface climatology files that these tasks generate are already available (e.g., from a previous experiment that used the same grid as the current experiment), then these tasks can be skipped, and the workflow can use those pre-generated files.

To skip these tasks, remove parm/wflow/prep.yaml from the list of task groups in the Rocoto section of the configuration file (config.yaml):

    taskgroups: '{{ ["parm/wflow/coldstart.yaml", "parm/wflow/post.yaml"]|include }}'

Then, add the paths to the previously generated grid, orography, and surface climatology files under the appropariate tasks in config.yaml:

   GRID_DIR: /path/to/directory/containing/grid/files
   OROG_DIR: /path/to/directory/containing/orography/files
   SFC_CLIMO_DIR: /path/to/directory/containing/surface/climatology/files

All three sets of files may be placed in the same directory location (and would therefore have the same path), but they can also reside in different directories and use different paths.

4.2.6. How do I restart a DEAD task?

On platforms that utilize Rocoto workflow software (such as NCAR’s Cheyenne machine), if something goes wrong with the workflow, a task may end up in the DEAD state:

rocotostat -w FV3SAR_wflow.xml -d FV3SAR_wflow.db -v 10
201906151800       make_grid      9443237   QUEUED              -      0      0.0
201906151800       make_orog            -        -              -      -        -
201906151800  make_sfc_climo            -        -              -      -        -
201906151800   get_extrn_ics      9443293     DEAD            256      3      5.0

This means that the dead task has not completed successfully, so the workflow has stopped. Once the issue has been identified and fixed (by referencing the log files in $EXPTDIR/log), users can re-run the failed task using the rocotorewind command:

rocotorewind -w FV3LAM_wflow.xml -d FV3LAM_wflow.db -v 10 -c 201906151800 -t get_extrn_ics

where -c specifies the cycle date (first column of rocotostat output) and -t represents the task name (second column of rocotostat output). After using rocotorewind, the next time rocotorun is used to advance the workflow, the job will be resubmitted.

4.2.7. How can I clean up the SRW App code if something went wrong?

The ufs-srweather-app repository contains a devclean.sh convenience script. This script can be used to clean up code if something goes wrong when checking out externals or building the application. To view usage instructions and to get help, run with the -h flag:

./devclean.sh -h

To remove the build directory, run:

./devclean.sh --remove

To remove all build artifacts (including build, exec, lib, and share), run:

./devclean.sh --clean
./devclean.sh -a

To remove external submodules, run:

./devclean.sh --sub-modules

Users will need to check out the external submodules again before building the application.

In addition to the options above, many standard terminal commands can be run to remove unwanted files and directories (e.g., rm -rf expt_dirs). A complete explanation of these options is beyond the scope of this User’s Guide.

4.2.8. How can I run a new experiment?

To run a new experiment at a later time, users need to rerun the commands in Section that reactivate the srw_app environment:

source /path/to/etc/lmod-setup.sh/or/lmod-setup.csh <platform>
module use /path/to/modulefiles
module load wflow_<platform>

Follow any instructions output by the console (e.g., conda activate srw_app).

Then, users can configure a new experiment by updating the environment variables in config.yaml to reflect the desired experiment configuration. Detailed instructions can be viewed in Section Parameters and valid values are listed in Section 3.1. After adjusting the configuration file, generate the new experiment by running ./generate_FV3LAM_wflow.py. Check progress by navigating to the $EXPTDIR and running rocotostat -w FV3LAM_wflow.xml -d FV3LAM_wflow.db -v 10.


If users have updated their clone of the SRW App (e.g., via git pull or git fetch/git merge) since running their last experiement, and the updates include a change to Externals.cfg, users will need to rerun checkout_externals (instructions here) and rebuild the SRW App according to the instructions in Section 2.3.4.

4.2.9. How can I add a physics scheme (e.g., YSU PBL) to the UFS SRW App?

At this time, there are ten physics suites available in the SRW App, five of which are fully supported. However, several additional physics schemes are available in the UFS Weather Model (WM) and can be enabled in the SRW App. The CCPP Scientific Documentation details the various namelist options available in the UFS WM, including physics schemes, and also includes an overview of schemes and suites.


Note that when users enable new physics schemes in the SRW App, they are using untested and unverified combinations of physics, which can lead to unexpected and/or poor results. It is recommended that users run experiments only with the supported physics suites and physics schemes unless they have an excellent understanding of how these physics schemes work and a specific research purpose in mind for making such changes.

To enable an additional physics scheme, such as the YSU PBL scheme, users may need to modify ufs-srweather-app/parm/FV3.input.yml. This is necessary when the namelist has a logical variable corresponding to the desired physics scheme. In this case, it should be set to True for the physics scheme they would like to use (e.g., do_ysu = True).

It may be necessary to disable another physics scheme, too. For example, when using the YSU PBL scheme, users should disable the default SATMEDMF PBL scheme (satmedmfvdifq) by setting the satmedmf variable to False in the FV3.input.yml file.

It may also be necessary to add or subtract interstitial schemes, so that the communication between schemes and between schemes and the host model is in order. For example, it is necessary that the connections between clouds and radiation are correctly established.

Regardless, users will need to modify the suite definition file (SDF) and recompile the code. For example, to activate the YSU PBL scheme, users should replace the line <scheme>satmedmfvdifq</scheme> with <scheme>ysuvdif</scheme> and recompile the code.

Depending on the scheme, additional changes to the SDF (e.g., to add, remove, or change interstitial schemes) and to the namelist (to include scheme-specific tuning parameters) may be required. Users are encouraged to reach out on GitHub Discussions to find out more from subject matter experts about recommendations for the specific scheme they want to implement. Users can post on the SRW App Discussions page or ask their questions directly to the developers of ccpp-physics and ccpp-framework, which also handle support through GitHub Discussions.

After making appropriate changes to the SDF and namelist files, users must ensure that they are using the same physics suite in their config.yaml file as the one they modified in FV3.input.yml. Then, the user can run the generate_FV3LAM_wflow.py script to generate an experiment and navigate to the experiment directory. They should see do_ysu = .true. in the namelist file (or a similar statement, depending on the physics scheme selected), which indicates that the YSU PBL scheme is enabled.