A restart run allows users to extend a run to a longer simulation period when there are reasons the entire simulation cannot be done at one time (e.g., not enough wall-clock time). It is effectively a continuous run made of two or more shorter runs.

When you run the initial WRF simulation, in the namelist, set "restart_interval" to the time you desire to have restart files (wrfrst_d0*) available. The output times of these files will be the times from which you will be able to begin your restart simulation.

**Note: Restart runs can also be useful for troubleshooting. For e.g., if your simulation crashed at a certain time and you want to put in print statements to determine what went wrong, you can use the restart files to start from a time right before the model crashes, instead of having to start from scratch each time.

 

 

 

Set-up WRF

For this exercise, you are not required to start over from the beginning. If you successfully ran the Single Domain case, you should have restart files you can use for this case.

1. Make sure you are in the /glade/scratch/$USER/practice_exercises/wrf/test/em_real directory.    
    
    
2. Edit the namelist.input file. The only namelist values that need to be changed are in the time_control record, and are highlighted below:
   
   

   run_hours = 12, run_minutes = 0, start_year = 2023, start_month = 03, start_day = 31, start_hour = 12, end_year = 2023, end_month = 04, end_day = 01, end_hour = 00, interval_seconds = 21600 history_interval = 180, frames_per_outfile = 1, restart = .true., restart_interval = 720,

   
   
   
3. Make sure you have your original wrfout_d0* files saved elsewhere (e.g., inside the single_domain/ directory), so they do not get overwritten.



4. For a restart, there is no need to re-run real.exe, as the wrfrst* file contains all of the initial condition information (and will serve to replace the wrfinput_d01 file), and will be used, along with the wrfbdy_d01 file to run wrf.exe. So simply submit the runwrf.sh script to the queue again.

   qsub runwrf.sh

   You can use the qstat command you used for the single domain case to check on the status, and look at the rsl.out.0000 file for the "success" message.

   If successful, this will generate the following new history files:

   wrfout_d01_2023-03-31_15:00:00
   wrfout_d01_2023-03-31_18:00:00
   wrfout_d01_2023-03-31_21:00:00
   wrfout_d01_2023-04-01_00:00:00
   

   
   

   Note Notice you do not get a wrfout file at the start time of 12 UTC. This is a safety feature to prevent overwriting the previously created file. If you wish to have a file output for the first time frame, you can add the following line *anywhere* in the &time_control namelist record. write_hist_at_0h_rst = .true.

Check your output:

• Check to see what is printed to the log files (rsl.out*).


• Tail the rsl.out.0000 file and look for "SUCCESS COMPLETE WRF".


• Use the "ncdump" command to see output times available in wrf history file.


• Use the netcdf data browser 'ncview' to examine your wrf output file,


• Generate graphics with one of the supplied packages.