Use WRF to perform high-performance computing

Background information

WRF is a next-generation mesoscale numerical weather prediction system that is designed for both atmospheric research and operational forecasting applications. WRF can produce simulations based on actual atmospheric conditions or idealized conditions. WRF uses a software architecture that allows parallel computation and provides system extensibility. The model can be used in a wide range of meteorological applications. For more information, visit the WRF official website.

Preparations

1. Create an E-HPC cluster. For more information, see Create a cluster by using the wizard.

   Configure the parameters of the E-HPC cluster. The following table describes the parameters.

   Parameter	Description

   Parameter	Description
   Hardware settings	Deploy a standard cluster that consists of two management nodes, one compute node, and one logon node. All nodes are ecs.c7.large Elastic Compute Service (ECS) instances. Each instance has 2 vCPUs, 4 GiB of memory, and one 2.7 GHz 3rd-generation Intel Xeon Scalable (Ice Lake) processor.
   Software settings	Deploy a CentOS 7.6 public image and the Slurm scheduler. Turn on VNC.

2. Create a cluster user. For more information, see Create a user.

   In this example, the username wrftest and the permission group sudo are used.

3. Install WRF and MPICH in the cluster. For more information, see Install software.

   Install the following software:

   • WRF-MPICH V3.8.1

   • MPICH V3.2

4. Install NCL in the cluster.

   NCL is used to process and visualize meteorological data. For information about how to install NCL, see Installing NCL.

   Note

   By default, CentOS images are installed with an earlier version of Python. Before you install NCL, you must upgrade Python. For information about how to download Python, see Download Python.

Step 1: Run geogrid.exe

The geogrid.exe program defines the simulation domain and horizontally interpolates static geographical data to the domain.

1. Log on to the cluster.

   Log on to the cluster as a sudo user. For more information, see Log on to a cluster.

2. Check whether the required software of WRF is installed in the cluster.

   export MODULEPATH=/opt/ehpcmodulefiles/
   module avail

   The following code shows an example of the returned output:

   ----------------------------------------------------------------------------------------------------------- /opt/ehpcmodulefiles/ ------------------------------------------------------------------------------------------------------------
   mpich/3.2       vnc             wrf-mpich/3.8.1

3. Load the WRF software environment.

   module load wrf-mpich/3.8.1 mpich/3.2
   echo $WPSHOME $WRFHOME

4. Copy the installed WRF Preprocessing System (WPS) and WRF software to the working directory.

   Note

   Replace $WPSCOPYHOME and $WRFCOPYHOME in the command with the actual working directory. In this topic, /home/wrftest is used as an example. The WPS and WRFV3 directories are generated in the working directory.

   cp -r $WPSHOME $WPSCOPYHOME
   cp -r $WRFHOME $WRFCOPYHOME

5. Go to the WPS directory, and download and decompress the geographical data file.

   Note

   In this example, the geog_complete.tar.gz file is used. You can download a different geographical data file based on your business requirements. For more information, visit the WRF official website.

   cd /home/wrftest/WPS
   wget https://www2.mmm.ucar.edu/wrf/src/wps_files/geog_complete.tar.gz
   tar -zxvf geog_complete.tar.gz

6. Link the GEOGRID.TBL file.

   The GEOGRID.TBL file determines which fields are interpolated by &geogrid.

   ln -s geogrid/GEOGRID.TBL GEOGRID.TBL

7. Edit the namelist.wps file.

   The namelist.wps file is a shared file of WPS. This file is used to configure the parameters of main programs, including geogrid.exe, ungrib.exe, and metgrid.exe. Each main program has an exclusive namelist record named &geogrid, &ungrib, and &metgrid. The three programs have a group record named &share. The following example shows the recommended values for the required parameters. For the parameters that are not described in the following example, use the default values. For information about the parameters and parameter descriptions of the namelist.wps file, visit the WRF official website.

   Note

   • In this example, the namelist.wps file is in the /home/wrftest/WPS directory.

   • Use ! to indicate comments in the namelist.wps file.

   ! The request parameters of &share.
   &share   
   ! wrf_core: specify the WRF dynamical core. Valid values: ARW and NMM. Default value: ARW. 
   wrf_core = 'ARW', 
   ! start_date: specify the start time of the simulation.
   start_date = '2005-08-28_00:00:00',  
   ! end_date: specify the end time of the simulation.
   end_date = '2005-08-29_00:00:00',     
   interval_seconds = 21600,
   ! max_dom: specify the total number of model domains, including nests. In this example, this parameter is set to 1.
   max_dom = 1, 
   ! # io_form_geogrid: specify the format of geogrid output files.
   io_form_geogrid = 2,    
   /
   
   ! The request parameters of &geogrid.
   ! # Specify information such as the parent domain, parent-to-nest domain, grid size ratio, and map projection.
   &geogrid
   parent_id = 1,
   parent_grid_ratio = 1,
   i_parent_start = 1,
   j_parent_start = 1,
   
   ! Specify the numbers of grid points in the west-east and south-north directions. For this example, set the values to 98 and 70.
   e_we = 98,       
   e_sn = 70,
   geog_data_res = 'default',
   
   ! Specify the grid lengths in the west-east and south-north directions. Unit: meters. For this example, set the values to 30000 and 30000.
   dx = 30000,     
   dy = 30000,
   
   ! Specify the projection mode. For more information, visit the WRF official website.
   map_proj = 'mercator'
   
   ! Specify the latitude and longitude of a known location in the domain.
   ref_lat = 25.00,
   ref_lon = -89.00,
   
   ! Specify the parameters of the map projection. The values vary based on the projection.
   truelat1 = 0.0,   
   truelat2 = 0.0,
   stand_lon = -89.0,
   ! geog_data_path = 'Path of static geographical data'
   geog_data_path = '/home/wrftest/WPS/geog'
   /
   
   ! The request parameters of &ungrib.
   &ungrib
   ! out_format: specify the format of the intermediate files that are generated by ungrib.exe and you want metgrid.exe to read. Valid values: WPS, SI, and MM5. Default value: WPS.
   out_format = 'WPS', 
   ! prefix: specify the prefix of the intermediate files. The prefix can include a path.
   prefix = 'FILE'
   /
    
   ! The request parameters of &metgrid. 
   &metgrid  
   ! fg_name: specify the name of the files generated by ungrib.exe.
   fg_name = 'FILE', 
   ! io_form_metgrid: specify the format of the metgrid.exe output file.
   ! Valid values: 1, 2, and 3. 1 indicates a binary file with an extension of .int. 2 indicates a NetCDF file with an extension of .nc. 3 indicates a GRIB1 file with an extension of .gr1.
   ! Default value: 2.
   io_form_metgrid = 2
   /

8. Interpolate static geographical data to the model domain.

   ./geogrid.exe

   After you run geogrid.exe, the geo_em.d0N.nc file is generated in the /home/wrftest/WPS directory. The following code shows an example of the returned output:

   

Step 2: Run ungrib.exe

The ungrib.exe program extracts meteorological fields from GRIB files.

1. Download and decompress the meteorological data file of Hurricane Katrina.

   Note

   In this example, the Katrina.tar.gz file is used. To download Katrina.tar.gz, click Katrina.tar.gz. You can download a different geographical data file based on your business requirements. For more information, visit the WRF official website.

   cd /home/wrftest/WPS
   wget http://www2.mmm.ucar.edu/wrf/TUTORIAL_DATA/Katrina.tar.gz
   tar -zxvf Katrina.tar.gz

2. Execute the following link_grib.csh script to link the meteorological data:

   ./link_grib.csh /home/wrftest/WPS/Katrina/avn*

3. Link the Vtable of the data file.

   In this example, Vtable.GFS is used. You can select a different Vtable based on your business requirements:

   ln -sf ungrib/Variable_Tables/Vtable.GFS Vtable

4. Extract the required meteorological fields.

   ./ungrib.exe

   After you run ungrib.exe, the FILE:YYYY-MM-DD_hh* file is generated in the /home/wrftes/WPS directory. The following code shows an example of the returned output:

   

Step 3: Run metgrid.exe

The metgrid.exe program horizontally interpolates meteorological fields to the model domain that is determined by geogrid.exe.

1. Link the GEOGRID.TBL file.

   The GEOGRID.TBL file defines how metgrid.exe horizontally interpolates meteorological fields to the model domain.

   cd /home/wrftest/WPS
   ln -s metgrid/METGRID.TBL.ARW METGRID.TBL

2. Horizontally interpolate meteorological fields to the model domain that is determined by geogrid.exe.

   ./metgrid.exe

   After you run metgrid.exe, the met_em.d0N.yyyy-mm-dd_hh:mm:ss.nc file is generated in the /home/wrftes/WPS directory. The following code shows an example of the returned output:

   

Step 5: Run wrf.exe

The wrf.exe program stores the forecast data.

1. Import the processing result of WPS.

   cd /home/wrftest/WRFV3
   ln -s /home/wrftest/WPS/met_em.d01.2005-08-2*.

2. Edit the namelist.input file.

   cd /home/wrftest/WRFV3/run
   vim namelist.input

   The parameters that are related to &time_control and &domains in the namelist.input file must be the same as the parameters in the namelist.wps file. The following sample configurations are used in this topic. For information about the parameters in the namelist.input file, see namelist.input.

   &time_control
   run_days                            = 0,
   run_hours                           = 12,
   run_minutes                         = 0,
   run_seconds                         = 0,
   start_year                          = 2005, 2005, 2005,
   start_month                         = 08,   08,   08,
   start_day                           = 28,   28,   28,
   start_hour                          = 00,   00,   00,
   start_minute                        = 00,   00,   00,
   start_second                        = 00,   00,   00,
   end_year                            = 2005, 2005, 2005,
   end_month                           = 08,   08,   08,
   end_day                             = 29,   29,   29,
   end_hour                            = 00,   00,   00,
   end_minute                          = 00,   00,   00,
   end_second                          = 00,   00,   00,
   interval_seconds                    = 21600
   input_from_file                     = .true.,.true.,.true.,
   history_interval                    = 180,  60,   60,
   frames_per_outfile                  = 1000, 1000, 1000,
   restart                             = .false.,
   restart_interval                    = 5000,
   io_form_history                     = 2
   io_form_restart                     = 2
   io_form_input                       = 2
   io_form_boundary                    = 2
   debug_level                         = 0
   iofields_filename                   = "extraoutput_d01.txt"
   /
   
   &domains
   time_step                           = 180,
   time_step_fract_num                 = 0,
   time_step_fract_den                 = 1,
   max_dom                             = 1,
   e_we                                = 98,    112,   94,
   e_sn                                = 70,    97,    91,
   e_vert                              = 30,    30,    30,
   p_top_requested                     = 5000,
   num_metgrid_levels                  = 27,
   num_metgrid_soil_levels             = 4,
   dx                                  = 30000, 10000,  3333.33,
   dy                                  = 30000, 10000,  3333.33,
   grid_id                             = 1,     2,     3,
   parent_id                           = 0,     1,     2,
   i_parent_start                      = 1,     31,    30,
   j_parent_start                      = 1,     17,    30,
   parent_grid_ratio                   = 1,     3,     3,
   parent_time_step_ratio              = 1,     3,     3,
   feedback                            = 1,
   smooth_option                       = 0,
   /
   
   &physics
   mp_physics                          = 6,     6,     6,
   ra_lw_physics                       = 4,     4,     4,
   ra_sw_physics                       = 4,     4,     4,
   radt                                = 10,    10,    10,
   sf_sfclay_physics                   = 1,     1,     1,
   sf_surface_physics                  = 2,     2,     2,
   bl_pbl_physics                      = 1,     1,     1,
   bldt                                = 0,     0,     0,
   cu_physics                          = 0,     0,     0,
   cudt                                = 0,     0,     0,
   isfflx                              = 1,
   ifsnow                              = 0,
   icloud                              = 1,
   surface_input_source                = 1,
   num_soil_layers                     = 4,
   sf_urban_physics                    = 0,     0,     0,
   /
   
   
   
   &fdda
   /
   
   &dynamics
   w_damping                           = 0,
   diff_opt                            = 1,      1,      1,
   km_opt                              = 4,      4,      4,
   diff_6th_opt                        = 0,      0,      0,
   diff_6th_factor                     = 0.12,   0.12,   0.12,
   base_temp                           = 290.
   damp_opt                            = 0,
   zdamp                               = 5000.,  5000.,  5000.,
   dampcoef                            = 0.2,    0.2,    0.2
   khdif                               = 0,      0,      0,
   kvdif                               = 0,      0,      0,
   non_hydrostatic                     = .true., .true., .true.,
   moist_adv_opt                       = 1,      1,      1,     
   scalar_adv_opt                      = 1,      1,      1,     
   /
   
   &bdy_control
   spec_bdy_width                      = 5,
   spec_zone                           = 1,
   relax_zone                          = 4,
   specified                           = .true., .false.,.false.,
   nested                              = .false., .true., .true.,
   /
   
   &grib2
   /
   
   &namelist_quilt
   nio_tasks_per_group = 0,
   nio_groups = 1,
   /

3. Initialize simulation data.

   ./real.exe

   After you run real.exe, the wrfinput_d01 and wrfbdy_d01 files are generated in the /home/wrftest/WRFV3/run directory.

4. Export the forecast data.

   1. Write a job script.

      vim wrf.slurm

      The following example shows the content of wrf.slurm:

      #!/bin/bash
      #SBATCH -N 1
      #SBATCH -n 2
      #SBATCH --cpus-per-task=1
      #SBATCH -J wrf-test
      #SBATCH -o wrf_test.log
      
      module load wrf-mpich/3.8.1 mpich/3.2
      mpirun -np 2 -ppn 1  -bind-to core:1 /home/wrftest/WRFV3/run/wrf.exe

   2. Submit the job.

      sbatch wrf.slurm

      After you run the job, a file whose name is in the wrfout_d01_[date] format is generated in the /home/wrftest/WRFV3/run directory. Example: wrfout_d01_2005-08-28_00:00:00.

5. Create NCAR Graphics images for the WRF result.

   Sample code: